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Are there known life forms that are able to transform mechanical energy into chemical energy?
Are there known life forms that are able to transform mechanical energy into chemical energy?
This question asks a similar subject, but more specific and has no answers.
The background of this question are thoughts about hypothetical life on tidally locked exoplanets of red dwarf stars, where light for photosynthesis is scarce but mechanical energy (storms and/or water currents) aplenty.

There are no known life forms that use mechanical energy as a primary form of metabolic energy (i.e., for generic cellular functions). Many life forms are sensitive to mechanical disruption in some way, so they do utilize mechanical energy, but in a very limited fashion (@David's answer touches on this), and of course many organisms have life cycles that somehow depend on mechanical transportation (seed/spore dispersal, traveling on the wind or ocean currents, etc).
I think the main physical problem is that mechanical energy just isn't available to biological cells in a form that can be converted to substantial chemical energy. They are small, and tend to have other great benefits for being small.
To use an ocean wave as an example, there is very little or no perceptible movement for a cell in that wave, besides an apparent increase and decrease in the force of gravity. The top and bottom of the cell are moving together with the flow of water, so there is no differential to operate on.
An E. coli weighs about 1 picogram. If it could capture all of the energy from falling from 1km in the air on earth, assuming no uncaptured aerodynamic drag, that would be about 10-11 joules.
If there are ~3000 kJ/mol of energy available from burning glucose, that means about 5 × 10-21 joules per molecule of glucose, so about 20 billion glucose molecules, which sounds like a lot but it is only 1 femtogram, 0.1% the weight of the cell.
Also note: in @David's answer he makes a very good point that in a way, using mechanical force to open a channel is indeed a form of energy usage and therefore a proof of concept that this could happen. To put that process in the same ballpark, this source (originally mentioned by @GerardoFurtado) gives the work necessary to open one of these channels at around 8 × 10-22 joules. The open latency for those channels is under 50 microseconds, but that still greatly limits the number of possible cycles per unit time. Chemical energy is just substantially more dense than mechanical energy is: that's why gunpowder superceded catapults (and even the trebuchet..).

Not an answer to the question, but a very useful consideration.

@GyroGearloose I'll add an answer to it, I guess I left it out a bit.

@BryanKause no hurries and no worries. Your consideration is appreciated.

'Open latency' do you mean the duration of the channel remaining open?

I'm a little disappointed that the answer is "No", but then, I didn't really expect evolution to bring something about that has copper wires, strong magnets and a wind turbine. I need some time to formulate a different question, with the same background. Osmotic energy comes to mind.

@Mockingbird The time from deflection of the tip links to when the channel is able to pass ions.

This is definitely not my field, and I have no interest in science fiction, but the question struck me as interesting, and brought me to an area of bimolecular science that may be relevant to the question.
First, in direct answer to the question, I do not know of any examples of life forms of the type you suggest.
However there are examples of biological processes involving mechanical movement resulting in the ‘release’ of electrical energy. The following recent paper drew this to my attention, and the introduction contains background reference to the phenomenon.
Electron cryo-microscopy structure of the mechanotransduction channel NOMPC.
It turns out (thank you @Bryan_Krause) that the electric current is the result of the opening of a ‘gate’ to dissipate a pre-existing ionic concentration gradient, established beforehand by the expenditure of cellular chemical energy in the form of ATP. Nevertheless, the opening of these gates must involve an effect on the conformation of the protein or protein complex involved in maintaining the gate, and can be regarded as the harnessing of mechanical energy to drive the complex from a conformation state of lower to one of higher free energy.
The amount of energy involved in this case may be quite low — a few hydrogen bonds compared to the order of magnitude higher energy of hydrolysis of ATP. However it is an interesting ‘proof of principle’. If minute amounts of mechanical energy can be transformed in this way, I wouldn’t bet against organisms being found in some niche that harvested more energy and used it to greater effect. As a primary source of energy for life? Perhaps not.

This is, indeed, really nice. However, that kind of receptor is not new, have a look at this image from Alberts, 15 years ago: https://www.ncbi.nlm.nih.gov/books/NBK26868/figure/A4107/?report=objectonly. Besides that, this is just a gate: It doesn't convert mechanical energy into chemical energy, it only allows the exchange of Na+/K+, as any other gate.

To add to what @GerardoFurtado wrote there are also receptors for mechanotransduction in  several sensory systems: all the different forms of touch, proprioceptive sensation in your muscles and tendons, auditory and vestibular systems, etc, and there are also cells that are somewhat more accidentally mechanotransducive (for example, if you press on the side your eye, you "see" things in the visual field corresponding to that part of the retina - please be careful). They all have in common that they utilize preexisting concentration gradients.

@BryanKrause — Thanks. I was wondering about that very point. Before I edit or delete my answer, can you tell me whether I would be correct in thinking that the mechanical energy is used to convert a protein (or protein complex) from a lower free energy structure (which maintains the gate closed) to a higher free energy structure in which the gate is (temporarily) open?

@David Yes I think you could state it that way, but it isn't clear to me whether there is actually a stable higher free energy state, I think it's better to think of it as elastic energy, but of course that contributes to the free energy.

I'm afraid that the mechanism only triggers the conversion of previously available chemical energy to electric energy, like a button on an electric torch triggers  the conversion of chemical energy in the battery to electrical energy used by the lamp. No energy added from mechanical sources. The mechanism looks worth mentioning, though.

I don't think the button analogy is valid. Pressing the button does not cause the transduction of one form of energy to another. If the example I cited invoves transformation of mechanical energy into a conformational change in a protein then even if it does not provide the energy for the initial concentration gradient, it is a proof of principle.

I have revised my answer in the light of the comments. If you voted for it and are now disappointed, please reverse your vote. If the revised answer is not considered useful I shall be happy to delete it.

I think the button analogy is actually good, if you simply add a spring that pulls the button back into place when you release it. The energy is in depressing the button against the pressure of the spring, which is a form of mechanical energy that is greatly analogous to the deformation of the tip links, which is also a mechanical energy. You can talk about it as a chemical energy but it's really no different. Also @David I do like your additions and also added to my own answer a discussion of the energy required to open those channels.

@Mockingbird — Thank you for your interest in my answer and Bryan Krause’s comment. The correct procedure for agreeing with a comment is to upvote it (assuming you have that privliedge). As with answers, it is not the purpose of comments to write "me too", with no explanation, as that is not helpful to the answerer (me in this case) or other readers. I would remind you that the question was not about finding analogies to describe biological mechanico-transduction processes but about their energetics. My answer attempts to address this by considering the free energy changes in the system.

You could also mention ATP synthase, which is the reverse of a pump -- it converts energy built up as a proton gradient across a membrane into mechanical, rotary energy before converting it into chemical energy as ATP.

Some biological molecules like collagen exhibit a piezoelectric phenomenon when mechanically manipulated with ultrasound waves (https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.123.238101).
This manipulation does not lead to the generation of chemical energy, but in a theoretically "hard" science fiction work, I'd suggest that one could legitimately write of organisms that have evolved to use collagen molecules or collagen-like proteins (say) to harness this voltage gradient as a potential source of energy to make copies of itself. Plants, after all, use a proton gradient and photosynthesis to store energy in ATP molecules, to the same end.
If there's an energy gradient that can be used to do work, life generally finds a way to take advantage.

I did read and article about some bacterial spores being used to generate electricity as they expand and contract. Not sure if that is a relevant answer but that's what came to mind when I read your question. https://www.sciencedaily.com/releases/2014/01/140127101242.htm

Regrettably, I can't open that link. It gives me "Error code: ssl_error_no_cypher_overlap". I've heard about such experiments, but what I know is that those organisms are only used to produce cheap micro-structures en mass. They are dead when the experiment starts. Nothing to do with biology. Maybe your link points to something different, but I can't verify it.

@GyroGearloose Yeah that's basically the gist of it: when the whole sheet dries out, it shrinks, so if it's fixed to a flexible material, that material bends. A biomaterial, in a way, but the transduction is not biological at all.

No, as the mechanical energy cannot be harvested at the lenght scale cellular life exists at. Cellular life exist at a length scale were viscosity is the primary force at work, a force which must be overcome by expending energy.
There is a nice article here that details what can be done with mechanis by small organisms/cells: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4451180/

The source you quote is a top journal, and the point you make may be valid, but an answer here must be comprehensible in itself — we can't be expected to go and read a paper to understand the answer.  So please edit your answer to explain why "mechanical energy cannot be harvested at the length scale cellular life exists at." and what viscosity has to do with this. I appreciate this is  a chore if English is not your first language, but it could make your answer much more useful to us all.

If you all want me to fine, but it will take quite a bit of physics to explain. I decided to give the shortest and most precise answer which wouldn't require an university degree to understand.

Simple realise that life exist at the micrometer scale and that the molecular machinery necessary to harvest mechanical energy would have to exist at the nanometer scale. At such small scale the individual interactions of atoms are much stronger than the mechanical energies applied. For instance cells can tolerate a couple of thousand g, while biomolecules such as proteins can survive several tens of thousands g. While mechanical influence can be sensed, it cannot be used to maintain ion gradients across membranes and therefore cannot drive ATP synthesis.


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Do amphibians feel pain?
It seems strange, but I always hear that toads and frogs don't feel pain.
Is this a true assumption? Do this species can feel pain?

Welcome to Biology.SE! What research have you done before asking it here?

Did you read the Wikipedia article... pain in aphibians? https://en.wikipedia.org/wiki/Pain_in_amphibians

Keep in mind that perception of pain is a higher nervous system response that protects the organism from further damage. Amphibians have different responses for protection. Such as receptors for vision, hearing and touch. If they do feel pain they do not seem to indicate that they do so. If a fish on a hook cried out in pain most people would never go fishing. It would seem that pain response is confined to mammals

Another load on this, logically impossible to proove due to problems of qualia. But amphibians are no such magical organism. They are just like any other animal.

According the the Wikipedia article, It is widely accepted by scientists that they feel pain, based on their opioid receptors and sensory physiology.
"Amphibians, particularly anurans, fulfill several physiological and behavioural criteria proposed as indicating that non-human animals may experience pain. These fulfilled criteria include a suitable nervous system and sensory receptors, opioid receptors and reduced responses to noxious stimuli when given analgesics and local anaesthetics, physiological changes to noxious stimuli, displaying protective motor reactions, exhibiting avoidance learning and making trade-offs between noxious stimulus avoidance and other motivational requirements."
en.wikipedia.org/wiki/Pain_in_amphibians

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same SNP rs# referenced to be found in two different genes
Two GWAS papers have referenced the same SNP (rs7442295), but one states it's found in the gene GLUT9 and the other states it's found in SCL2A9. The ncbi dbSNP says it's in SCL2A9, and I thought that the rs number was unique to each SNP, so how can it be in two different genes? I'm really new to GWAS, so it might be a really stupid question, but any advice would be great!

The NCBI dbSNP entry shows rs7442295 to be in the gene SLC2A9, not SCL2A9 stated in the original question.
As the Wikipedia article for SLC2A9 says, synonymous names for SLC2A9 include:

solute carrier family 2 (facilitated glucose transporter), member 9, GLUT9, GLUTX, UAQTL2, URATv1, solute carrier family 2 member 9

So GLUT9 and SLC2A9 refer to the same gene, and the two papers are not in conflict about the location of the rs7442295 SNP.

Both mutations have caused the same changes in serum uric acid. In other words, one of those papers is older. Those are the same genes.

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Bug ID? Lower New York
Found it on the floor of my basement laundry room in a mostly wooden house in the woods in Westchester County, NY. However I had done a mountain hike (same general area) and I may have brought it from there on my pants or something, but I'm not sure.
When it noticed me it stopped moving, but it was still alive because when I put it in this cup for a pic I accidentally flipped it upside down and it started squirming to get itself upright.

That's not an insect but a crustacean (it has more than 6 legs).
It is a woodlouse (plural woodlice). A woodlouse is one of the few terrestrial isopode crustacean. There are about 5000 known species of woodlice. I have no idea which one is the one you captured!

Woodlice are generally appreciated in gardens as they control pests. They sometimes get inside searching for moisture. While it may not be pleasant to have woodlice at home (just because they look disgusting to many, me including), they do not spread disease or cause much damage.


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Insect ID. Montreal, Qc (Canada)
I've found this bug in my appartment today and I was wondering what insect it is? Thank you.

This is a "click beetle" (Coleoptera, Elateridae). They have this name because of the loud click sound they produce. They are related to fireflies (Lampyridae), and some click beetle species are themselves luminescent.
According to the link above:

A spine on the prosternum can be snapped into a corresponding notch on the mesosternum, producing a violent "click" that can bounce the beetle into the air.

I don't know about those North American beetles, but in South America I've seen click beetles jumping more than 30cm in the air.
Here is a photo of a click beetle in Montreal, from the Pest Control Canada website, which looks like your specimen:

Unfortunately, the entomologist that identified the animal in the photo above didn't narrow it down to Genus or Species.

Thank you. You "saved" the life of my friends. They thought it was an "American Cockroach"... hahahaha

The second photo of the question is of a little help in learning the genus this beetle isn't; the shape of the scutellum (an oblong plate between the front wings at their base) eliminates the American genera of the subfamily Cardiophorinae (which have the scutellum somewhat resembling a valentine, with the point directed aft).


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Debug Fresno; why are the released mosquitos said to be sterile?
I saw in the news that Verily Life Sciences will participate in an experimental release of sterile male aedes aegypti mosquitos in Fresno, California. Aedes aegypti is considered an invasive species in California, and can be a vector for human disease including dengue fever, zika, and chikungunya (according to the video). See the Verily blog Debug Fresno, our first U.S. field study and/or the attached YouTube video Introducing Debug Fresno.
The released male mosquitos will carry a bacterium called wolbachia, which when transferred to the female during mating will prevent eggs laid by the female from hatching. Wobachia presence, parasitism and mutualism with insects is widespread, and Wikipedia's article on it even includes a section on applications to human-related infections.
Question: Are the males said to be sterile because of the bacteria which results in nonviable eggs, or are they also incidentally sterile in addition to being vectors for the wolbachia bacteria (and eggs were presumably fertilized by other matings)?

I haven't read too much into it, but I think both is correct. The males are sterile and they make the females subsequently sterile.

@CMosychuk that would be my guess too. Since the males don't carry anything genetically that would reduce the population, releasing fertile males would be counterproductive. But I don't know if one can call otherwise fertile males sterile because they carry the bacteria, so I think the use of "sterile" here does not refer to the impact of the bacteria on the eggs.

different, but in the news First-ever US release of genetically modified mosquitoes begins in Florida Keys

I've just asked: Why do OX5034 GM mosquitos require the presence of tetracycline to survive? What does the drug do in this case?

Males are effective sterilization vectors
You can think of male mosquitos as fertile only in theory. Any mating of these mosquitos will generate no offspring whatsoever, so they are effective sterile and they spread this characteristic to females.
The bacteria makes they sterile in the end, the same way any disease in others cases.

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Effect of forced breathing on RBC size

Microcytosis, i.e. decrease in the size of RBCs occurs:
– In iron deficiency anaemia,
– During prolonged forced breathing and
– When osmotic pressure of the blood is increased.

I am unable to understand how forced breathing results in microcytosis.

My attempt: I think prolonged forced breathing results in low CO2 concentration in blood which would lead to low H+ ion concentration , but this would lead to hypo-osmic plasma, which would certainly produce macrocytosis.

Source:Textbook of physiology

I thought H+ concentrations cause pH changes in blood and protein concentrations cause osmotic changes.

Co2 in the blood will be in the form of H2CO3, which will dissociate into H+ and HCO3- , if the rate of respiration is increased then, this is lost from the blood, so some amount of osmotically active species is lost from plasma. You are right in that osmotic changes, are mostly due to proteins, and it was  just a guess to solve the original problem.

I am hypothising too here:for maintaining constant blood viscosity->reverse of hamburgers->decreases swelling of RBC->makes the RBCs comparatvly irregular->viscosity rises.feedback occurs decreases the no. of such RBCs thus viscosity is controld.If I findrefrences I would post it as an answr later.

Forced breathing, a.k.a hyperventilation, causes hypertonic dehydration.
According to Greger and Windhorst, Comprehensive Human Physiology (2014):

Loss of more water than NaCl leads to hypertonic dehydration and hypernatremia. In this condition the intracellular volume is marked decreased, whereas the extracellular volume is less compromised. Possible causes of hypertonic dehydration include excessive loss of hypotonic fluid (e.g., sweat) or hyperventilation.

Therefore, the decrease of the size of red blood cells is due to the dehydration following hyperventilation.
Source:

Greger, R. and Windhorst, U. (2014). Comprehensive Human Physiology. Berlin: Springer Berlin.


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Which organism built this 2 cm long sandy tube?
I found this tube and wondered which animal built it.
It is 2 cm long and has an entrance/exit hole on one side. The material seems to be sandy.
I assume it is for breeding purposes.
Before finding the tube, I saw an unfamiliar kind of wasp around (could also be a hornet), with very long black legs. However, I could not find a wasp or hornet that builds such tubes, so it could be unrelated.
Location is Germany.
My questions are: which organism built this structure and should I expect anything crawling out one day? Or is it unfinished, since the entrance isn't closed?

Just found this post, which seems to be related: https://biology.stackexchange.com/questions/49088/what-wasp-like-insect-breeds-in-clay-pots-with-dead-spiders

This is the nest of a Mud dauber, also known as Mud wasp. This was possibly made by a Black and Yellow Mud dauber based on the following information.

The nest of the black and yellow mud dauber is a simple, one-cell, urn-shaped nest. 1*

As for expecting something coming out of it? I doubt it, as the nests are sealed after depositing an egg.

After building a cell of the nest, the female wasp captures several spiders. The captured prey are stung and paralyzed before being placed in the nest (usually 6-15 per cell), and then a single egg is deposited on the prey within each cell. The wasp then seals the cell with a thick mud plug. 2*
Eventually, the hatching larva will eat the prey and emerge from the nest.

You are right. Just saw mommy coming back to continue her work :) Interestingly, they were introduced in Germany in the 70s/80s.

@another'Homosapien' Quoting sources [1][2]: "Not normally aggressive, but can become belligerent when threatened." & "Stings are rare due to their usually peaceful nature, however nests are aggressively defended."

This wasp is thought to be responsible for the deaths of over 180 people when an airliner crashed after the wasp built it's nest in a tube - https://en.wikipedia.org/wiki/Birgenair_Flight_301


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Triosephosphate isomerase deficiency

Triose phosphate isomerase deficiency, a rare condition, is the only glycolytic enzymopathy that is lethal. This deficiency is characterized by severe hemolytic anemia and neurodegeneration.

How can I relate this enzyme deficiency to hemolysis?

My attempt:
1- Accumulation of DHAP is causing intracellular fluid to be more osmotic leading to cell bursting.( Then why don't we see the same in outer cells?)
2-Lack of glucose may lead to less ATP production, Na/K pumps work less, thus disturbing membrane potential, which finally may cause hyper-osmic ICF and then henolysis. ( But why don't RBC take twice the amount of glucose?)

Source: Biochemistry 8th edition by Jeremy M. Berg John L. Tymoczko Gregory J. Gatto, Jr. Lubert Stryer

Unlike most of the cells in a human body, erythrocytes (or red blood cells) don't have mitochondria (because they are basically O2 carriers), and don't perform Krebs Cycle or Oxidative Phosphorylation. Therefore, they depend exclusively on glycolysis to produce their ATPs.
According to the Genetics Home Reference (from the NIH, National Institutes of Health) page about triosephosphate isomerase deficiency:

The anemia in this condition begins in infancy. Since the anemia results from the premature breakdown of red blood cells (hemolysis), it is known as hemolytic anemia [...] TPI1 gene mutations lead to the production of unstable enzymes or enzymes with decreased activity. As a result, glycolysis is impaired and cells have a decreased supply of energy. Red blood cells depend solely on the breakdown of glucose for energy, and without functional glycolysis, red blood cells die earlier than normal. (emphasis mine)

Thus, since erythrocytes depend solely on glycolysis as energy source, there is a marked accumulation of DHAP toxic sub-products (Ahmed et al., 2003).
Sources:

Reference, G. (2017). triosephosphate isomerase deficiency. [online] Genetics Home Reference. Available at: https://ghr.nlm.nih.gov/condition/triosephosphate-isomerase-deficiency#genes [Accessed 16 Jul. 2017].
Ahmed, N., Battah, S., Karachalias, N., Babaei-Jadidi, R., Horányi, M., Baróti, K., Hollan, S. and Thornalley, P. (2003). Increased formation of methylglyoxal and protein glycation, oxidation and nitrosation in triosephosphate isomerase deficiency. Biochimica et Biophysica Acta (BBA) - Molecular Basis of Disease, 1639(2), pp.121-132.

But why don't they utilise twice the amount of glucose?

In the absence of TIM half of the G3P is present for carrying glycolysis.

G3P dehydrogenase can act on it to form glycerol-3-phosphate, which can be used for lipid synthesis.

Well, I shared a source that clearly explains the issue. I believe the best idea is just deleting my answer.

please add this to your answer , https://www.ncbi.nlm.nih.gov/pubmed/14559119

the main culprit here seems to be formation of advanced glycation products.


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Is this an insect? Which one?
I found this animal, which I suspect it's an insect, on the floor of a kitchen in Spain some days ago. It's about 8-10 mm long. I don't think I've ever seen it before. What is it?

This looks like a silverfish (https://en.m.wikipedia.org/wiki/Silverfish )

It is a silverfish. It is a 'basic lineage' in the insect class. You'll find it here on OneZoom.org.
Silverfish are considered household pests although I don't think they spread disease nor cause much damage (thanks to @WilliamBligh for his comment). They typically live in the canalization (bathroom, kitchen) or anywhere that is wet enough. In a building, they may be hard to get rid of as they can easily move from one apartment to another. You have to keep your place very clean and eventually use toxins such as Permethrin or Deltamethrin.

While they are considered a "household pest", they are to the best of my knowledge not harmful. Even contamination of food is, again to the best of my knowledge, undocumented (but sometimes assumed). If they are not present in large numbers, I would advise not to poison them.
Edit to add: pyrethroids are hardly "specific" toxines.

You're right. Thanks for your comment. I edited the answer accordingly.


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Cooperativity of haemoglobin and oxygen dissociation curve of haemoglobin
Haemoglobin shows positive cooperativity with oxygen. When an oxygen atom binds to one of hemoglobin's four binding sites, the affinity to oxygen of the three remaining available binding sites increases; i.e. oxygen is more likely to bind to a hemoglobin bound to one oxygen than to an unbound hemoglobin. This is referred to as cooperative binding.

Haemoglobin reaches 50% saturation when the partial pressure of oxygen reaches about 28 mm Hg. Now partial pressure had to be increased by about 70 mm Hg for haemoglobin to reach maximum saturation. If haemoglobin is a cooperative molecule, once haemoglobin reaches 50% saturation it should be easier to attain ~100% saturation. But it is taking a difference of 70 mm Hg. Whereas 50% saturation requires only 28 mm Hg.
Hope this makes sense.
Please answer this and correct my understanding.
Thank you

As you may notice from the graph you provided, there actually is no such thing as true 100% saturation: there is always an asymptotic approach to 100%, regardless of cooperativity.
Let's think, though, of what is actually plotted in that graph: $p_{O_2}$ effectively oxygen concentration, versus number of total percentage of binding sites that have an $O_2$ bound.
However, this also means that as you go up on the y-axis, the number of sites available to bind also goes down. So even if those sites have a high affinity for oxygen, there aren't as many of them open!
That's one big problem with the type of plot you show: it doesn't highlight the cooperativity very well. Therefore, people sometimes plot this information in a "Hill plot", with an algebraic shuffling and log scaling like this:

See Wikipedia
...where $\theta$ represents the fraction of receptors bound to ligand, and $L$ is the (unbound) ligand concentration. $n$ is the Hill Coefficient, i.e., the cooperativity.
When plotted this way, you can easily see the effect of the cooperativity of hemoglobin versus myoglobin (which has cooperativity of 1, because it has a single binding site):

http://cbc.arizona.edu/classes/bioc462/462a/NOTES/hemoglobin/hemoglobin_function.htm via Fig. 7-13, Nelson & Cox Principles of Biochemistry, 3rd ed., 2000

I agree with everything in the answer  from Bryan Krause but, in case it helps, here is the explanation that I came up with.
One way to think about this is in terms of the familiar MWC two-state model, which is essentially what you have used to frame your question.
If the concentration of oxygen is high enough for 50% saturation then, to a first approximation, most of the haemoglobin molecules have bound some oxygen and in terms of the whole population of molecules they are mostly in the relaxed, high affinity state in which any unoccupied binding sites will have the dissociation constant that is characteristic of that state. So all you are seeing in the right half of the curve is the usual hyperbolic binding curve for the relaxed form. For any saturation curve this is the behaviour that falls out of the mathematical description of the binding.
In other words, in terms of your word 'easy' it is always less easy to bind the next increment of ligand as you approach saturation because the concentration of occupied binding sites has increased so the rate of dissociation has also increased.

Yes. The basic fallacy is to think that co-operativity implies a sort of exponential increase in rate. One really has to understand that however efficient the protein-ligand interaction is, complete interaction only occurs at infinite ligand concentration. This is the basic idea of the hyperbolic  curve being explained by the Michaelis-Menten model of specific enzyme active sites, and the mathematical treatment that corroborated it. And describing the behaviour of haemoglobin in terms of oxygen binding detracts the student from its importance in the release of oxygen.

@David Agreed, it can be quite a challenge to persuade students that the key innovation in the design of haemoglobin is the reduction in affinity for oxygen that cooperativity achieves.


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Corrupted chromosome will be in any cell of body if zygote was corrupted?
For example, zygote had abnormal number of chromosome (45, 47, 48 etc) or corrupted chromosome. And fetus was born. Then it means that in any cell of newborn's body there will be the same not normal or corrupted amount of chromosome?

The terms 'corrupted chromosome' and 'corrupted zygote' are very unusual and quite loaded. Mutations occur all the time (of the order of 1-10 mutations per individual per generation in humans, Drake et al. 1998) and it is unclear how big a mutation needs to be so that you talk about "corruption".
But in any case, yes, the egg will copy itself via mitosis to create the whole body. As such any mutation (whether a small substitution or a chromosomal duplication) present in the egg will be transmitted to all the daughter cells and will therefore be found in the entire body. Note that many of the changes in chromosome numbers lead to unviable zygotes and the baby never develop fully.
Note that during mitosis, sister chromatids are being separated and therefore the number of chromosome copy should not matter much in the general case.

The answer of @Remi.b is true in general case. Still, we can consider at least two mechanisms which will lead to fetus mosaicism.
First one is a mitotic recombination. It is a rare process of recombination in a somatic cell which can result in unequal genotypes in daughter cells. Therefore, if one chromosome of zygote possesses some minute mutation it is possible that after first division only one of daughter cells will have got a mutation. In such case, about half of fetus's cells will be mutation free.
The second possible process is a back mutation. They are such mutations that restore genotype to a state of the wild type. According to this paper, such mutations are not so rare in human cells. As a result, the fetus will consist of both mutated and wild type cells.
It is important to say that such mechanisms are quite rare and will work only for small mutations (i think only for point mutations).


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Species ID from Hungary

I found it on the wall, it was calm for 15 minutes. Central Europe, Hungary. Never seen anything like this. I have two more pictures.

This appears to be a Gastropacha Quercifolia, the Lappet Moth.

It is found in Europe and Northern and Eastern Asia.
The wingspan is 50–90 mm. The females are larger than the males. The moth flies from June to July depending on the location. Source


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Are there any alternatives to the Epicentre product Plasmid Safe?
I need to remove any traces of linear DNA (both single and double stranded) from a ligation reaction while keeping circular DNA intact. Up to now, I have used Epicentre's Plasmid Safe to do the job. I would like to try another solution (mostly because of the unreliability of our supplier: it takes weeks to get a batch!).
Has anyone replaced Plasmid Safe with other nucleases? Which one?
I have been looking at the NEB nucleases and I was thinking to use ExoV and T together to get rid of any linear DNA (both ssDNA and dsDNA). Does anyone have any other solution to propose?

"any other solution" How about separating them on a gel?

I would like to avoid gel-purification, the input DNA is already low, plus, some linear DNA is running at the same height of the circular one. I really need to digest specifically the linear ss and ds DNA.

alec_djinn, did combining ExoV and T work for you? I am also looking for methods alternative to Plasmid Safe. Thank you!

Yes, it worked. All the linear DNA is digested. But be careful to do not let the reaction go too long. In my case, 15 min was enough to digest 500 ng with 5 units of both enzymes. Try it out.


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Purpose of K+ channels in action potential
I understand that they serve to repolarize the neuron after the Na+  influx. What I don't understand is why this is important.
Meaning, let's say all the K+  channels disappeared. So now the potential is up near +50 mV about. It doesn't go back down quickly, because the K+  channels aren't there. Instead, we have to wait until the Na+/K+  pump can restore the proper intra-/extra- cellular balance between them. And then the neuron can fire again.
I can see that it will take longer for the potential to be restored. But don't we have to wait until the Na+  concentration is restored before we can fire again anyway? If we don't wait, wouldn't that interfere with maintaining sufficient/proper extracellular Na+ concentrations (which I would assume would have other effects)? And the same amount of time will be needed for the Na+ balance to be restored.
So what do we really gain by having a way to restore the charge differential?

Great question! However, your question is based on some misconceptions about what polarization means and how ion movement is involved, as well as the difference between equilibrium and the time it takes to get there. That's okay - it's a mistake that many many people learning about neurophysiology make, including instructors.
Na+/K+ concentrations actually change very very little during an action potential. The Na+/K+  pump establishes the concentration gradient, not the resting membrane potential. The resting membrane potential is caused by the concentration gradient plus the relative permeability of different ions via the Goldman equation: specifically, that permeability to K+ is much much higher than Na+.
When you open voltage-gated Na+ channels during an action potential, the relative permeability to sodium increases dramatically, so the new "equilibrium potential" is closer to the reversal potential for sodium (again, use the Goldman equation). There will be a net flow of ions (mostly Na+ coming in) until that new equilibrium potential is reached.
However, voltage-gated Na+ channels inactivate quickly, so that equilibrium isn't really reached. Instead, as the Na+ channels close, the new equilibrium potential is back near the original resting potential (for a third time, use the Goldman equation), because the primary permeability is to K+ through leak channels, and therefore the net current flow direction changes.
Okay, so what's the need for the voltage-gated potassium channels in all this? Well, the rising phase (sodium phase) of the action potential is fast because there is a really high conductance to Na+ so lots of Na+ can flow quickly in. In comparison, there is a lot less conductance of K+ through the leak channels. If all you have are leak channels, it takes a long time to return to rest. Equilibrium potential is just that: the equilibrium. It takes time to get to equilibrium. Voltage-gated K+ channels speed up that return to rest.
What if you had no K+  conductance, including no K+ leak channels? Well, then it doesn't matter at all what the relative concentration of K+ is inside and outside the cell: check the Goldman equation! You can't really have no conductance to anything at all, but if there is no dominant ion then the membrane potential will be something around zero. In that condition, the charge imbalance of the Na+/K+ pump process can contribute a couple mV, but nothing more than that.
All that said, to address your specific questions:

I understand that they serve to repolarize the neuron after the Na+ influx. What I don't understand is why this is important.

It's important for speed and for the minimum refractory period between action potentials. Nervous system activity would slow way way down if action potentials could only occur every 100 ms.

Instead, we have to wait until the Na+/K+ pump can restore the proper intra-/extra- cellular balance between them. And then the neuron can fire again.
But don't we have to wait until the Na+ concentration is restored before we can fire again anyway?

Na+/K+ pump is only needed to maintain ion balance over a very long term. On the time course of a single action potential, the concentrations of Na+ and K+ do not change appreciably. That's not what repolarization is.

So what do we really gain by having a way to restore the charge differential?

Speed!
You can also see my answers on some related questions:
Why is it possible to calculate the equilibrium potential of an ion using the Nernst equation from empirical measurements in the cell at rest?
Why does K+ moves out of the cell?

Dude, leaving something for me too! +1 anyways...

Seems like you've pitched your answer at a higher level since its becoming difficult to get your point (that too, without any diagram/graph/equation!). Don't worry for answer length if longer only means better. Everyone knows that the question is quite broad ;)


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can somebody please Identify this queen ant?

hi, i found this queen in France and i want to know if it is a species i can take back home to England. i cant identify her since the only queens I've ever kept are Lasius Niger so i would like some help please!!

Please don't. It is never ever a good idea to import insects. The species is irrelevant, even a native species can be genetically different.

Oh, ok, i had no idea. im still kinda new at ant keeping. I only go to France for the Summer holidays so will i have to let her go?

that would be my advise, yes.

+1 to RHA's suggestion, but it isn't just genetic difference: insects (and any other animal or plant) can carry disease as well.

Just to add: it is often not only a bad idea biologically to carry insects to new locations (even different habitats within the same state/region/country), it is also often times illegal. Glad to hear you're releasing it where you found it :)

There are 4 main families in France. Formicinae, Dolichoderinae, Myrmecinae ans Ponerinae. This is a an ant in the subfamily Formicinae because it is large and has only one segment between the thorax and the abdomen. You can deduce that because the thorax and the abdomen seem very close. This particular ants is a queen of the genus Formica (wood ants) from the general aspect. The presence of wings indicate this is a reproductive individual and because the eyes are small compared to the rest of the head it is a female. The color and the general shape and the size would allow any trained observer to identify the genus Formica, although no formal criteria can be seen on this picture. Formal criteria require inspection of the funicula, a part of the antenna, which cannot be seen on this picture. For references please visit http://antarea.org, http://cle.fourmis.free.fr and read Seifert - Ameisen Mittel und Nordeuropas. Lutra.

Your answers need to be backed up with some sources and explanations.

The issue is that most of the time, when identifying insects on bad pictures, there isn't any formal character available. Identifications are often based on the general aspect of the insect by a trained observer.


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Biology experiment with algae method help
I'm planning a biology experiment I need to complete. I was planning on measuring the affect of pH on algae growth. I chose chlorella to be the test algae I use (are there any algae that would be easier to test?) and I have no idea how to measure the growth. My school does not have a spectophotometer, just basic biology and chemistry stuff. Also how can I change the pH of the water for my different samples? I'm a beginner and don't really have much experience so any help is appreciated!

For growth you could measure the mass of algae before and after the experiment. If you have a centrifuge you can pellet the cells or use a filter to remove the culture medium. Alternatively, if you have access to a hemocytometer and a microscope, you could get an accurate cell count that way.
For controlling pH, you'll need a buffer in your culture medium. You should select a buffer with a pKa close to the pH you want to test and then titrate the pH of the medium with a strong acid or base (HCl or NaOH). Make sure to check the pH before and after the experiment to be sure that it didn't change due to growth of the algae.

Maybe also mention cell counting with a haemocytometer- although these are not inexpensive.

@AlanBoyd Neither are microscopes...

A slower but easier way than pelleting in a centrifuge is pour off the water and let the algae dry out, then weigh the dried mass.
Get pH paper to check pH of each grow cup full of algae each day.
You can raise pH to around 8 with baking soda (sodium bicarbonate).
You can buy sodium carbonate (washing soda) in a hardware store.  It is cheap.  That will get your pH to 10+ which is higher than you need.

Make sure to get pure stuff, not with additives like perfume or other surfactants.
You can lower pH down to 2.5 with ascorbic acid or vitamin C.  A bottle of 100 is cheap and they crush easily.
Get a bunch of jars or old soda bottles and in each one make a bunch of solution of the pH you want.  So you will have a 2.5 stock bottle, a 3 stock bottle, a 4, a 5 on up.  Then you can top up your algae grow jars as they dry out.  Or better: pour out the old water and pour in new.  Don't pour out your algae by accident.
Last: you want this algae to grow like mad when conditions are good.  Pure water will be low on nutrients.  I recommend a dilute solution of Miracle Grow.

Maybe a teaspoon per liter.
I can envision 8 2liter soda bottles, each filled up and each with a different pH made either with washing soda or vitamin C.  Each 2L bottle has 2 tsp of miracle grow in it.
Each algae grow jar is a 12 or 20 ml drinking water bottle.  3 bottles per pH level.  Big number on each showing pH.  Put them in a row in the sun.  Change the water every 2 days.  Take a photo every day.
When you are done fish out the seaweed and dry it.

I've never worked with algae, but can you be sure that you aren't pouring out cells with the medium?

The algae will probably grow as a sticky mat.  A few lost cells will not matter.   You can hold it down with a spoon and pour out most of the water then replace.  Check this.  http://irnas.eu/bio%20lab%20symbiolab/2016/06/03/collecting-and-growing-algae   An idea: just use scummy pond water.  What grows, grows.  You will still be able to determine biomass at the end.  But you may find different organism types take over the jar at different pH which is also very cool and shows the flexibility of an ecosystem.


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HAR1 speedy mutation
From wiki:

Human accelerated region 1 (HAR1) is a segment of the human genome found on the long arm of chromosome 20. It is a Human accelerated region. [..] These 49 regions represent parts of the human genome that differ significantly from highly conserved regions of our closest [living relatives, the chimpanzees] in terms of evolution.

What could explain those differences?
A back of the envelope computation shows that in the course of 8mio years, at a rate of 64 mutations per generation, one can expect 1% of mutated basepairs. Indeed, the HAR1 of length 106 bp has 1.08 substitutions in the chimp. But humans have 13.93. (Data: see the table in this article.)

Can you please show how you computed the 1%? When you state the HAR1 of length 106 bp has 1.08 substitutions in the chimp, you mean substitution compared to what species? But humans have 13.93 substitutions compared to chimps I suspect? Or maybe you made an attempt at reconstructing the hypothetical sequence of the ancestor and compared to it? Or maybe you referred to some paper who sequenced a fossilized genome?

@Remi.b: yes, I was wondering also, but I think both numbers refer to the most recent common ancestor. At 64 mutations per generation over 400'000 generations, that's roughly 25mio mutations among 3bn bp, or roughly 1%.

But where did you get these numbers from? For example, I can't see the number 13.93 in the linked wikipedia articles.

Substitution rate at neutral sequences
The rate of substitutions at neutral sequences is given by the mutation rate. It si a very simple and classic result. It is because the probability of each new neutral mutation to fix is $\frac{1}{2N}$ (which you can calulate from a Moran branching process as well as from a simple Wright-Fisher model of genetic drift) and there are $2N\mu$, new mutations at each generation (where $N$ is the population size and $\mu$ the haploid mutation rate), resulting in a substitution rate of $2N\mu\frac{1}{2N} = \mu$.
Substitution rate at non-neutral sequences
A beneficial mutation has a probability higher than $\frac{1}{2N}$ to fix, while a deleterious mutation has a probability lower than $\frac{1}{2N}$ to fix. Therefore, the more beneficial mutations there are, the higher is the substitution rate. There are a number of approximations to the fixation probability of a non-neutral mutation. For example, using diffusion equations, one can approximate the probability of fixation of a deleterious mutation with selection coefficient $s$ by $\frac{1-e^{-\frac{4s}{N}} }{1-e^{-4Ns}}$ from some Kimura paper.
This rate of substitution therefore depends upon the selection scenario. It is lower than $\mu$ in conserved sequences and it is high than $\mu$ in sequences that undergo positive selection. So, the reason for such fast evolving sequences is just that they are under positive selection.
How about HAR1?
Without looking for more accurate statement form the scientific literature, the same wikipedia article you cite says

HAR1A is active in the developing human brain between the 7th and 18th gestational weeks. It is found in the dorsal telencephalon in fetuses. In adult humans, it is found throughout the cerebellum and forebrain; it is also found in the testes.[1] There is evidence that HAR1 is repressed by REST in individuals with Huntington's disease, perhaps contributing to the neurodegeneration associated with the disease

It already gives you a vague idea of potential selection pressures on those sequences in the human genome.

The rate is higher in sequences that undergo positive selection is a non-explanation to me. What is the mechanism? Is the mutation rate under "neutral selection" actually dampened (namely 13-fold?)?

I am not sure I understand what is unclear to you but let's try to make our way through it. A beneficial mutation has a probability higher than $\frac{1}{2N}$ to fix, while a deleterious mutation has a probability lower than $\frac{1}{2N}$ to fix. Therefore, the more beneficial mutations there are, the higher is the substitution rate. Does that clear things up?

Ok, so the "mechanism" is statistical: mutations do not easily result in substitutions because, being diluted in the population, they are weeded out. So in absence of selection pressure, the substitution rate is lower than the mutation rate. Yes? Maybe I'm not using the terminology correctly.

The exact number of substitutions is definitely is stochastic process. In absence of selection, the substitution rate is $\mu$. If mutations are often beneficial, then the substitution rate is higher than $\mu$. If mutations are deleterious, then the substitution rate is lower than $\mu$. You said So in absence of selection pressure, the substitution rate is lower than the mutation rate.. Well it depends upon whether selection is purifying or positive.

Ok, thank you. I upvote for potentially useful pointers, but cannot accept the current answer due to lack of clarity.


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Why does colchicine not affect the source plant itself?
Colchicine, being a mitotic poison that blocks spindle fibre formation, should affect its source plant. It should also stop its cells from dividing. So how do they grow?
I think that there might be some cells that synthesise it seperated (by many layers of cells) from other cells. So the rest cells are not affected.

Colchicine is an alkaloid and a secondary metabolite of the plant- a crocus, primarily functioning to protect the plant (like, from consumption by herbivores).
WHY COLCHICINE DOES NOT AFFECT THE PLANT:

It is transported far away from its site of production to the tissue storing it so does not come in contact with normal metabolically active plant cell machinery.
In the storage tissues colchicine is compatmentalised in vacuoles specific for colchicine storage.

The vacuoles are bounded by tonoplast which contains special proteins that facilitate active uptake of colchicine from the cytoplasm into the vacuole protoplast but do not conduct the movement of colchicine from the vacuole to the cytoplasm.
The scientific studies are detailed here.

all_licenses: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/


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Why would evolution favor blue as a color in bugs?
This question arose when I saw a metallic blue - black bug some while ago. I can't remember the species name now, but a quick google search will show that such bugs do exist. I'm down with green and black - camouflage, right? But what is the case for blue color? What kind of an advantage does it provide so that they have survived to this date?

Similarly, you could ask

Why are bees yellow?
Why are some frogs so colourful?
Why widowbirds have such long tails?
Why do peacocks have such a tail?

There are a number of reasons why such traits could evolve. The main reasons are:

Sexual selection (esp. intra-sexual selection when it comes to colors)
Mimicry (esp. batesian mimicry)
Aposematism

I let you investigate further by yourself through reading the linked wikipedia articles.
For the specific beetle, you have seen, it will be impossible to address the question unless we know the species.

Also consider that insects (and their predators) often see different parts of the spectrum than humans do.


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Solitary wasp larval behavior
Once placed in proximity to its future meal, how long does it take for the larva of a solitary parasitic wasp to begin feeding? I have several books on wasp behavior, but none address the time involved. An internet search also proved fruitless. I am asking out of curiosity and also to ensure accuracy in a story I am working on. I am sure it varies, I am just trying to get a general idea. For example, is it possible for larvae to begin feeding as soon as they are deposited?
(Edit: I added details to this question thanks to the first answer I received on this question)
(Edit: I've spent some more time looking into this and thought I'd share some information, should anyone be interested. Indeed, larvae can begin feeding within two days of being deposited. The larvae of Cicada-Killer Wasp (Sphecius speciosus), for example, begins feeding in 2 to 3 days, according to "The Strange Lives of Familiar Insects" by Edwin Way Teale. In "The Hunting Wasp" by John Crompton, the introduction sets a general range of 2 to 3 days, although I have read online of some wasp larvae taking longer.)

It depends on species and situation.
There are a lot of different solitary wasps, the kind you are referring to are parasitic wasps, that lay their eggs in or on a host for the larvae to feed on before they pupate to reach the final stage of their lifetime.
Some larvae that consume a host in groups take as little as twelve days to consume their host and eat their way out.
However, this wasp species can even have their larvae remain in the larval stage through winter and adapt through seasons. it's entirely dependent on what sort of wasp you're asking for what the time span would be for a larva to mature.

Thank you for your answer! I tried to upvote it but am too new.  What I'm wondering is when the larvae might begin eating. Could they start as soon as they are deposited by a wasp? I understand it will vary.

@AdamOrth They could indeed start eating fairly soon after the wasp has deposited them, the eggs do have to hatch first but that could be a matter of hours.

Thank you, I suspected this but was not sure.


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In myosin II are regulatory and essential light chains calcium binding proteins or sites of phosphorylation?
According to my medical physiology by Rhodes and Bell their description is as follows:

the essential light chain is necessary for myosin stability, and the other chain called the regulatory light chain is phosphorylated during muscle activity and serves to modulate muscle function*

However, according to molecular biology 4th edition:
it states that the light chains both exert their function via Calcium binding, they make no mention of phosphorylation.
So do light chains regulate myosin by calcium binding, phosphorylation or both ?

The answer is both, the regulatory light chains , regulate myosin by phosphorylation which  can be dependent or independent of $\ce{Ca^2+}$.
Medical Physiology:

The activity of the myosin regulatory light chain is in turn regulated through phosphorylation by $\ce{Ca^2+}$ -dependent and $\ce{Ca^2+}$ -independent kinases.

Source claiming calcium is essential for phosphorylation in tarantula skeletal muscle:

Contraction is modulated in many striated muscles by $\ce{Ca^2+}$-calmodulin dependent phosphorylation of the myosin regulatory light chain (RLC) by myosin light chain kinase.

Calcium independent phosphorylation of regulatory protein by MLCK4:

We find that MLCK4 is also expressed abundantly in cardiac muscle, and structural analyses indicate that it is a $\ce{Ca^2+}$/calmodulin (CaM)-independent kinase, in contrast to $\ce{Ca^2+}$/CaM-stimulated cMLCK.

thank you for the answer! Does the calcium binding and/ or phosphorylation change the confirmation so as to modify the ATPase or the actin binding site ?

Read the section below figure 11.27 at https://www.ncbi.nlm.nih.gov/books/NBK9961/


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What chemicals will kill P1 Phage but not E. coli?
I'm working with E. coli and P1 Phage. I'm wondering if there is some chemical agent that will kill or disable P1 but leave E. coli untouched? It is not enough to just prevent infection. It must destroy the Phage.

No such chemical exists. Otherwise we would use it whenever we have a phage breakout in labs across the world.


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Is Hydrogen rich water safe and beneficial for health
Is Hydrogen rich water safe and beneficial for health ? I just bought a Hydrogen water machine to try and relieve muscle inflammation.

What (the heck) is a "Hydrogen water machine"?

You should use Magnesium... 60 percent of humans are deficient in magnesium but it is used in hospitals to treat inflammation, they inject it in asthma patients who are having an acute attack into their bloodstream. it helps with cramps, stiffness, bad sleep and other stuff. nerves have massive amounts of magnesium and calcium in them.

Results
The consumption of hydrogen-rich water for 6 weeks reduced reactive oxygen metabolites in the blood and maintained blood oxidation potential. QOL scores during radiotherapy were significantly improved in patients treated with hydrogen-rich water compared to patients receiving placebo water.
Conclusions
Daily consumption of hydrogen-rich water is a potentially novel, therapeutic strategy for improving QOL after radiation exposure. Consumption of hydrogen-rich water reduces the biological reaction to radiation-induced oxidative stress without compromising anti-tumor effects.


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Where are interneurons in Autonomic Nervous System?
According to  the following, it implies that preganglionic neurons are interneurons.

Interneuron called preganglionic neuron whose cell body is situated in the "intermediolateral" column of spinal cord( also called 'lateral column').1

From this:

The interneuron (connector neuron) of somatic system has cell body in the dorsal horn and terminates in the ventral horn, while that of ANS has cell body in the intermediolateral horn and terminates in the autonomic ganglia....In the ANS, there are two efferent neuron chains between CNS and the effector organ: first efferent neuron (pre-ganglionic neuron) has its cell body in CNS while the second efferent neuron (post-ganglionic neuron) has its cell body out-side the CNS in the ganglion.

But this source implies quite opposite:

The spinal sympathetic interneurons that most directly influence the activity of sympathetic preganglionic neurons after spinal cord injury....

So which one is correct?

Please read Dot 2,3,4 on right column of that page, then it implies same as of first link.

It sort of depends on your definition of interneuron. Many school-level textbooks suggest that any neuron that has neurons both pre and post synaptically are interneurons. Therefore both the preganglionic neuron and the spinal sympathetic interneurons could be considered interneurons. This means that all neurons in the brain are interneurons and vastly oversimplifies the CNS.
I would argue that it's probably more helpful to think of the preganglionic neurons as "projecting" neurons, as they come down the spinal cord. The post-ganglionic neuron is more like a motor neuron.
Edit: I answered a similar question in more detail here: Is the bipolar neuron of the retina considered a sensory neuron?

So, what's the extra neuron in link 3?

Most likely a small, localised interneuron, residing solely within a confined region of the spinal cord. Edit, it will receive input from nearby neurons and send output to other nearby neurons.


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Wasp nest destroyed by some big wasp like insect: is that the queen?
I had a small wasp nest in my bathroom. Initially there were only two to three wasps but the number increased to eight.
Today morning a big wasp-like insect (shown in the image below) came to the nest. I thought that it was the queen but it ate all the larvae and destroyed the nest.
Can someone please tell me if this is a normal behavior of a wasp? Is the "big wasp" their queen or another species?

The wasp is a Ropalidia marginata
The assailant is a greater banded hornet .
There is a video of one attacking a wasp nest here: https://www.youtube.com/watch?v=BPLRpEkNv8Q
Hornets can attack wasp and bee hives and decimate them. In europe there is an invasive species of hornet from japan which is twice as big as the european hornet.
The abdomen of the hornet is about half of the size of the animal. The abdomen of the queen Ropalidia marginata is about 1/3rd of the animal, she has very similar markings as the hornet, it seems to have evolved as a copy cat that consumes larvae. http://drkrishi.com/ropalidia-social-wasp/
You must add location information to search for animals by region and find the species. I only knew it was india/pak because of the avatar.

It is in India Bangalore. Thanks for the help!

What kind of individual is wasp photo you give? It doesn't have the black and yellow pattern you mention about the queen.

If you see the photo from the question, it is the small wasp on the right of the nest, you can see the similarity. the pics of the queen from the same species are on the page by drkrishi.


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What are negative and positive after potentials?

After depolarization: is the slow repolarization phase which follows a rapid fall in spike potential and extends up to attainment of the RMP level. It is called phase of negative after potential and lasts for about 4 ms.
After reaching the resting level (–70 mV) the potential further falls and becomes more negative (–72 mV).This phase is called after hyperpolarization or phase of positive after potential.

What is the reason for naming them as negative and positive after potentials?
My attempt: I think we are naming them based on the direction
of current, i.e. during after depolarisation membrane potential is going further negative , so the name negative after potential, and during after hyper polarisation, membrane potential is going from hyper polarised state to resting state, so its named as positive after potential.
Am I correct?

Source:Textbook of physiology

Yes, you are correct. The negative current is hyperpolarising the axon and the positive current is returning it to baseline from a hyperpolarised state.
They are often referred to as inward/outward (negative/positive respectively) currents as well, due to the direction of the flow of ions. Which is further compounded when you start looking positive/negative ions.
Inward currents are inflow of +ve charge, or outflow of -ve charge.
Outward currents are vice-versa.

One doubt: we can see that during After hyperpolarization phase only last half of curve is having positive slope ( so positive current) then what about initial half in which curve is having negative slope( so negative current).

I'm not sure I follow, from your source, the trace drops to about -72mV immediately before point E. The bit from where it crosses -70 to E is the negative after potential.

Ah! got it, I was just confused by the Fig2.1-12 on pg52. Thanks.


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Why did humans lose their tail during evolution?
Most mammals seem to have tails. Even human embryos start out with a tail. But here we are with nothing but a tail bone that hurts when we trip over backwards. What is it good for? Why don't humans have a tail to wag around?
Some science fiction (like Avatar) even portrays a tail as something sexy. And we all have experienced that a third arm of some kind would be very useful once in a while. Especially since humans stand up a lot of the time it could help us keep balance.
Is there any utilitarian evolutionary explanation for why we don't have tails any more? Is it only because we try to be different?

The tail serves a variety of complex balance tasks in locomotion, turning, jumping, aerial balance, hanging, and most mammals have a tail, save for other examples, i.e. rabbits, pigs, capibaras, manx cats, seals and bats, lemmings and hamsters have mini tails.

All the previous large apes related to humans lost their tail millions of years ago. The reason why that occured are multiple and mixed. Multiple good explanations have been suggested.
Gibbons are some of our most monkey-like ape cousins. If you see how they move, they run on two legs rather than 4. Monkeys with tails are less adapted to walking and their pelvis is angled differently. https://www.youtube.com/watch?v=b9Pt2qgSqJw
Large animals with small tails, such as caribou, hippos, elephants, deer, seem to keep some kind of tail, however with chimpanzee type animals, once the tail became small it didn't stay on as a mini-tail. So would it make sense for chimpanzees/humans to have small tails like hippos or very long ones? If a chimp can run on 2 legs, that leaves it two hands to catch the tail of another competing chimp.

The big apes move differently to small apes: big apes live on the ground more, they don't run in trees as much, they move differently, they are larger, they have completely different body ratios for arm and leg size, and there have been a wide variety of propositions for hundreds of years on this topic without a particularly clear reason being accepted for which great apes don't have a tail.

My take away is that three is company. Two hands outcompeted the tail. I suppose the tail would just get stuck in all sorts of stuff anyway. Unlike our very sensitive fingertips.

@LocalFluff: OTOH, consider elephants, who seem to do quite well by putting their "tail" (AKA trunk) at the front.

And then there's this, from the news today: http://www.sciencemag.org/news/2017/07/watch-robotic-appendage-give-humans-third-arm  Mount it a little differently, and there's your prosthetic tail :-)

In 2021 an elementary genetic point mutation was found to coincide with the presence or absence of the tail about 25 million years ago, so it's not a complicated feature that takes millions of years, it's a basic random mutation that can happen in 1-2 generations in a population. It happened at the same time as there was a dramatic change in monkeys towards apes that have good bipedalism and inhabit a new ecological niche. The tail mutation could be a cause and/or a consequence. The corresponding animals are: Gibbons.

Gibbons are close to the oldest human ancestors that lost their tail. They branched off from monkeys ~20 million years ago and they have even more impressive climbing skills, they are entirely arboreal and run waving their arms around in a clumsy way. Gibbons don't have a quadrupedal running gait like big babboons and squirrels, who run like small dogs and cats.
If you study these videos of gibbons, think... Would a tail benefit or hinder these animals?
They are some of the most impressive climbers of all because their opposeable thumbs are well developed and their arms and legs are more ambidextrous than running animals.
So if you think back in time, for the point genetic mutation, potentially there was a family of monkeys living together that had individuals with tails and individuals without tails.
image of the latest primate phylogeny

(+1) A likely tale!


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Empty room, Room full with stuffs & Auditory adaptation to reflection of sounds
Background
When a room is full with stuffs like furniture, electronic utilities, books etc. it's hard to hear reflections of sounds made by us (talking, playing an instrument, sound from falling objects).
But, when the room is empty we quite easily hear the reflections of sound which is according to physics perfectly legit.
However, what seems interesting to me that when we suddenly empty a room with stuffs, the change in hearing reflection of sounds has a great impact on our ear. I personally experienced  this phenomenon several times while emptying a room for cleaning and other purposes.
Question

Is it because of the sudden nature of the phenomenon described above, the phenomenon seems to have a greater impact on our ears?
What would happen if we try to get used to the empty room environment? Would sensory adaptation slowly diminishes our sensibility towards reflection?

Just to be clear, what do you mean when you say "great impact on our ear" ?

I am wondering if maybe this type of question could be answerable on Physics.SE? I have a feeling that there may not be a biological explanation, but maybe it could be explained by the soundwaves themselves. I'm sure someone there knows how sound-waves interact with different surfaces and themselves, and I'm sure someone there knows how noise-detection works.

@Bob I think it's more psychological than physical!

Well, bring it to Psychology.SE then. I was just trying to let you know that there might be more options =D

@Bob There is no Psychology.SE

Riight.. CognitiveScience.SE

@Dexter Greater impact than what it used to have!

@Bob But there is a psychology tag in this site


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Once food has been properly cooked is it absolutely safe?
If you properly cook food (let's say in the oven for 2 hours) will there be no risk left? no pathogen will survive this?

Depends on what you consider "food". ;)

Some pathogens are more harmed by heat than others, some are obliterated at 80, 110. Some pathogens require large numbers to hurt you, a couple of tired E-Coli will not harm at all, but a mass of them is dangerous. generally you can boil water for 10 seconds at 100 degrees and it is considered sterilized, in fact that's how they sterilize orange juice, they pass it through a pipe and boil it for a minimum time, say 10 20 seconds.

Also depends on the elapsed time between cooking and eating.  Leaving cooked stuff in the refrigerator for a few weeks is probably not a good idea.  Nor is cooking stuff like meat that's started to smell...

You won't be able to eat the food at a temperature that is even close to reducing pathogens. So in any case, the time it spends cooling down will always be time which allows potential pathogens to grow.

No, no food is ever 100% safe, Prions for instance can survive anything short of incineration, spores can land on food in the transition from oven to wherever, some bacterial spore can survive high temprature, ect.

Oven does not sterilize!
High temperatures like the one you get in a normal oven (250 degrees Celsius) can kill a great deal of microorganisms but not all of them.
Also, consider that spores (including bacterial spores) can survive to extreme temperatures.
Lab-grade sterilization is obtained by high temperature, at high pressure and high humidity conditions. Have a look at this web page to get a glimpse.
So, even though you can reach high temperatures in a modern oven, you miss the high pressure and uniform humidity needed for a proper sterilization.
Also, as already mentioned by @John, it depends on what you mean for safe. 1) your food can be contaminated with toxic molecules and they may not be degraded by temperature alone, so even if you get a microbiologically clean food, that doesn't make it necessarily safe. 2) Many reactions occur during the cooking process, some of them may lead to accumulation of toxic products like acrylamide, in such a case, cooking make your food less "safe".
Here some literature on the topic:
http://www.annualreviews.org/doi/pdf/10.1146/annurev-food-041715-033144
http://science.sciencemag.org/content/301/5635/934
http://aem.asm.org/content/71/7/3556.full
http://www.sciencedirect.com/science/article/pii/S1878614611001164
https://www.readbyqxmd.com/read/16672493/high-pressure-mediated-survival-of-clostridium-botulinum-and-bacillus-amyloliquefaciens-endospores-at-high-temperature
Just to be clear, I didn't find any scientific paper describing any organism able to survive at 250 C. However 1) it has been shown that spores may survive to dry heat much better than wet heat and some microorganisms have been described to be thriving at more than 120 C. 2) The oven temperature is not the same of the food temperature, in many cases such a heat does not reach the "food core". 3) Unless you cook under a fume-hood, your food gets contaminated as soon you open the oven door.

Any refs for the claim that some microorganisms can survive 250°C even as spores?

I have one https://cals.arizona.edu/PLP/courses/plp329/sporeref.pdf  pg. 552, it's only about B. subtilis and it was tested only up to 160 C. I am checking for more...

-1 This paper gives the well known value of 120°C of wet heat (the one also used in cooking) needed to kill spores of Gram-positive bacteria in reasonable time. This is where the autoclaving temperature comes from.

To autoclave, you need pressure as well. Without it, you will not get any sterility. I assure you, I deal with microbiology all day long and I am doing it for more than 10 years. If you autoclave bacterial medium without setting the right pressure, you will see molds growing into perfectly sealed bottles in a few weeks. The same occurs if the humidity is too low. Temperature alone is not enough. Look at the plot on pg 552, dry heat for 1h at 160 C and still you don't kill all the spores.

@har-wradim:  250°C oven temperature does not mean  250°C food temperature, especially if you're cooking something large.  A turkey, for instance, is considered "done" when it reaches an internal temperature of about 75°C, which takes several hours.

No.
Staphylococcal food poisoning is super common.  The bacteria that cause it are killed by cooking but if they have a chance to grow and make their toxin before they are cooked, the toxin is not destroyed by cooking and can make you sick.  I think this type of food poisoning constitutes most cases where you throw up and have diarrhea about 6 hours after you eat but you rally within 2 days.
From linked source (CDC)

People who carry Staph can contaminate food if they don’t wash their
  hands before touching it. Staph can also be found in unpasteurized
  milk and cheese products. Because Staph is salt tolerant, it can grow
  in salty foods like ham. As it multiplies in food, Staph produces
  toxins. Although Staph bacteria are easily killed by cooking, the
  toxins are resistant to heat and so cannot be destroyed by cooking.
  Foods at highest risk of transmitting Staph toxins are those that
  people handle and then do not cook. Examples are sliced meat,
  puddings, pastries, and sandwiches. Food contaminated with Staph toxin
  may not smell bad or look spoiled.

No for several reasons.
If poisonous bacteria previous got into the food, there could be poisons left over that cooking isn't guaranteed to get rid of.
Some bacteria pack themselves into spores when they are cooked. Spores are incredibly hard to destroy. You might consider irradiating them. A common way to counter this: cook food, let it cool (prompting the spores to unpack themselves), then cook it again.
Then you have the risk of "kitchen-to-table" contamination where the food gets contaminated after cooking and cooling due to poor hygiene practices.


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Can Thraustochytrids such as Schizochytrium do photosynthesis?
I know they belong to the phylum of heterokonts and that they are being heterotrophically grown on an industrial scale but I can't seem to find any reference to them being grown photoautotrophically. People call them marine algae yet there is no mention of photosynthesis.
I did find this paper which says they have several carotenoids so I assume they have those because of their LHC's and photoprotection. It would be great if anyone had some more detailed information (papers) regarding their properties.

I think not.
from Kingdoms and Domains: An Illustrated Guide to the Phyla of Life on Earth By Lynn Margulis, Michael J Chapman. as found on google books
You will see there are no chloroplasts depicted.  These are eukaryotes and so to do photosynthesis they would need chloroplasts which should be evident.

I was hoping for a more definitive answer since photosynthesis jumps in and out of the heterokont lineage but your information is a lot better than what I found. Thanks!


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Is there any way to differentiate between a contractile and a non contractile vacuole by observation alone in any given organism
I have read about distinguishing them using osmotic experiments in books and here as well.
But is there any thing common (on a biochemistry level) from which I can tell if a vacuole is contractile or non contractile irrespective of the organism taken and only by observing?

Contractile vacoules are usually surrounded by distinguishing structures

The contractile vacuole has several structures attached to it in most cells, such as membrane folds, tubules, water tracts and small vesicles. These structures have been termed the spongiome; the contractile vacuole together with the spongiome is sometimes called the "contractile vacuole complex (CVC). The spongiome serves several functions in water transport into the contractile vacuole and in localization and docking of the contractile vacuole within the cell.

This type of arrangement is not common in non-contractile vacuoles like gas, sap or food vacuoles.


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Diagnosing pathogenic illnesses with DNA analysis?
I am wondering if there are techniques for diagnosing pathogenic illnesses with DNA analysis.
For example, imagine a person has a staph infection on their skin. A scraping could be taken and then analysed. In this cases there will be two sources of DNA: the person and the staphylococcus bacteria. My understanding is that statistics can be done to separate the two and thereby positively identify the DNA sequences unique to the staphylococcus, and thus exactly diagnose the pathogen, even telling what family or strain it is.
Now, imagine a harder situation. The patient has a viral infection like a cold. In this case we may still be able to do the same procedure using nasal mucus, but there may be other passive viruses in the mucus. Is it possible?
Now, imagine an even harder situation. The patient has a internal viral infection causing a fever. There blood has thousands of retroviruses in it. Is there any way to isolate the virus causing the fever and get its DNA?

This is all routine, to the point of being trivial.  Genome-based diagnosis is very common and is the preferred approach for many, if not most, infectious diseases. Here is a list of over 150 FDA-approved genome-based assays for pathogens.
Some quick examples include influenza:

Rapid Molecular Assays
Rapid molecular assays are a new kind of molecular influenza diagnostic test for upper respiratory tract specimens with high sensitivity and specificity.1 One platform uses isothermal nucleic acid amplification and has high sensitivity and yields results in 15 minutes or less. Another platform uses RT-PCR and has high sensitivity and produces results in approximately 20 minutes.
Other Molecular Assays
Reverse Transcription-Polymerase Chain Reaction (RT-PCR) and other molecular assays can identify the presence of influenza viral RNA in respiratory specimens with very high sensitivity and specificity.

--Influenza Signs and Symptoms and the Role of Laboratory Diagnostics
RSV ...

A newer test protocol (RT-PCR) is more reliable and is replacing the antigen-detecting test in many hospitals and community laboratories.

--Respiratory Syncytial Virus (RSV) Infection
Meningitis ...

Over the past several years, conventional and real-time PCR assays have been developed for detection of bacterial meningitis pathogens. Reliable assays have been extensively evaluated using invasive clinical isolates and/or clinical specimens from around the world (8, 12, 15, 17, 29, 35, 52, 60). In general, validated assays should have high sensitivity and specificity. They can be used as complementary approaches in bacterial disease diagnosis.

--https://www.cdc.gov/meningitis/lab-manual/chpt10-pcr.html
and many, many more.
An important trend now is using genome detection methods to look for many different potential pathogens in a single sample; these "lab on a chip" approaches (e.g. here are just entering clinics but will probably be routine in a few more years.

That is fine if you know what you are looking for, but what if it is uncertain what the disease is? Can you test a sample against all known diseases, or only a few likely guesses?

@ImprisonedRhesus - The "shotgun" approach you ask about is unwise and exceedingly expensive. Physicians who do not use their intelligence in making presumptive diagnoses and testing for the most likely culprits first do no one (or no institution) any service. Rare diseases do exist, and are a diagnostic challenge, but to use this approach (test for everything) is just sloppy and calamitously expensive.

Okay, so you seem to be saying that we can do DNA diagnosis, but only if we have a good idea of what it might be already and can check for that specific possibility, is that right?

@Imprisoned Rhesus That's a very different question from your original one, which asks about detecting specific agents. I suggest you ask it as a separate question. Short answer, there are research-level tools for identifying unknown agents, but as far as I know none that are clinically approved


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Do exon deletions in C.elegans mutants necessarily result in nonsense mediated decay of the transcript?
I am trying to write out my research proposal about a project in C.elegans. There are multiple mutants of the factor that I want to study, each with different mutations. I know that a mutation that abolishes the promoter and transcription start site of the gene will most likely be a null mutant. But what about strains that have internal deletions? For example, if I were to generate mutants missing specific exons such that there was a predicted ORF for the gene product, is this transcript automatically targeted for nonsense mediated decay? I was told that this was a C.elegans specific process (deletion mutants are often protein null?), but I am having trouble finding this information.

I would assume that it may depend on the target in question. If the exon you remove causes errors in splicing of the surrounding introns, degradation will be the likely fate for the transcribed RNA. If the introns are correctly spliced, I would assume that you may end up with a deletion variant of a protein. Whether the deletion variant is functional or not will likely depend on which exon you remove.


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Does PCR amplification affect microarray or DNA biosensor results?
I've noticed that PCR amplification is commonly done before analyzing the DNA sample with microarrays or biosensors.
However, won't amplification biases or errors mess up the gene expression profile results you get from a microarray? Secondly, does that mean amplification only allows you to get qualitative information from say an electrochemical biosensor? (rather than actual quantitative information about DNA concentration)

Anytime you have PCR in a protocol, yes, you might mess up the quantification.  So you do as little PCR as you can, so that it stays in the linear range, preserving the different abundances of templates  (qPCR after all is the gold standard for quantifying expression), and you hope that there are minimal PCR biases between templates.

Yes, it does.
That is why you should include positive and negative controls and repeat the experiments multiple time to then average the results.
In general, amplification by PCR is biased by sequence-dependence efficiency. For several reasons (among which GC content, annealing mismatches PCR buffer and the timing and temperatures of the cycling steps) a particular template can be over- or under-estimated.
For example, if one sequence is amplified 10% more than another in one round, it will be 1.1^30 = 17.4 times more abundant after 30 amplification cycles.
Here some literature on the topic:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2292241/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3628873/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3129672/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2727727/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4433096/
This doesn't mean that you can't get quantitative information. PCR is used to get quantitative results in many fields of research. You "just" have to be sure you are doing it correctly. Be aware that experimental confounders may mess up your results, so be critical when you analyze your own data.


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Does crossover happen between chromosomes from grandparents?
Rephrasing question: does crossover happen after sperm and egg meet each other, but before formed fetus starts to grow?
As I understand sperm and egg of human are haploid cells. That means this cells undergone meiosis and chromosomes crossover before meet each other. If so then crossover happened between a pair of chromosomes which came from parents of the parent of the fetus, not between chromosomes of mother and father of the fetus.
Am I wrong?

No, you are right.

Your question and your rephrased question aren't asking the same thing, so you may want to edit your question.
Crossover occurs during meiosis, which is a type of cell division that occurs in the generation of gametes, during which of course only the chromosomes from one of the eventual parents would be present. Meiosis doesn't occur in the fetus, except eventually in the germ line cells.

Thanks for answer. So crossover happen before sperm and egg cells meet each other, right?

@wandalen Yes: it occurs when the progenitors of those cells divide to produce gametes.


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How much of my ancestry comes from each grandparent?
Three of my grandparents were Eastern European, back at least several generations. I recently discovered that I am less than 25% Eastern European, the rest being Western European and other. How likely is this?

On average, 25%, because you have 4 grandparents, and all of your genetic material came from them as a collective. Of course it's possible to be more genetically similar to a particular grandparent by random assortment of chromosomes, but the average will be 25%.
Genetic tests can't tell you what your ancestry is (companies implying this are probably misleading you on purpose). At best, they can tell you how correlated certain features of your genome are with people from a certain geography. Even people who are currently live in Eastern Europe will not test as "100% Eastern European." There is far too much mobility and breeding of populations across geography and far too much variation within populations.


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What is head of a bone?
For most of the long bones head is the proximal end, but for metacarpals and Ulna, head is the distal end. Why are their distal ends called as heads?
What's the criteria for calling an end as head end?

Why voted to close? I have searched on internet but could not find any literature about it, all I see is " head is usually the proximal end" .So I asked it here. What should I mention in the section MY attempt in the question?

Because it's easy to google, but I'm answering it anyway.

Here is a head and a neck:

Anatomy is fairly straightforward. regarding individual long bones, "heads" are curved ends of bones distal to a narrowing called a neck of a bone. Take the radius:

See how the radial head (curved) is just distal to a narrowing (neck)?
The ulnar head, though, is at the opposite end, because the proximal end isn't rounded, but the distal end is.
Metacarpal heads are distal (see blue area):

The humeral head is probably most obvious:

So, the head of a long bone is not determined by the position (it can be proximal or distal) but by the contiguous shapes.

When will you answer about chassaignac's tubercle?

@JM97 - I don't appreciate your pushiness. I would have thought you'd have accepted that I'm no longer involved in that thread. You're welcome for my answering this, btw.a completely voluntary activity.

You were the only person to say that you know about it, so i was eager to know about that.

I'm curious, do bones have two necks or only one neck, proximal to the head, in that case?

@DavidCian - Yes, only one.


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Pressure change in atria
Background:It is said that during the phase of isovolumetric contraction , due to sharp rise in the ventricular pressure, there occurs bulging of AV valves into the atria producing a small but sharp rise in the intra-atrial pressure called c-wave.( in the second cycle of diagram).

Question: I am unable to understand why is then pressure in atria falling after the end of isovolumetric phase, even though the pressure in the ventricles is rising, so this should further bulge the AV valve or atleast( due to action of papillary muscles) have same pressure, So why is pressure falling?

Because the atrial volume is increasing: https://www.researchgate.net/profile/James_Chase/publication/237098593/figure/fig15/AS:341279209738243@1458378712255/Figure-1Evolution-of-atrial-and-ventricular-variables-during-a-cardiac-cyclePanel-A.png

The curve you are talking about is JVPJuglar Venous Pressure Curve.
You are talking avoit x-decent after c pulse.
The downward deflections of x decent is produced by the atrium relaxation and the downward movement tricuspid valve.
This causes decrease in atrial pressure.
A new fascinating question could be why x-decent is greater than y-decent.
Good luck.


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Agarose gel Ladder smear
We are having trouble with agarose gel electrophoresis. It used to work a couple of months ago but now the ladder always look smeared. We switched the components (1x TBE, 100bp ladder, different type of agarose and voltage) and equipment. We also tried 1.2%, 1%, 1.5% and 2% agarose.
I would appreciate it if someone can help us.

Was the alternate ladder new, the agarose? If all your components are old or being improperly stored or handled and thus degraded, you will get smearing.

Are you sure that your TBE is at the right dilution? And that you're using TBE to make the gel and also as the buffer for running?  That sort of wavy line looks like what you might get if you'd made the gel with water instead of buffer, or run it with water instead of buffer.  You could also try using TAE to make/run the gel as a sanity check.

I second the possibility of gels cast with water instead of TBE buffer. It is a classic mistake that many people make the first time in the lab. Another classic would be making gels from a 10x TBE stock and using 1x TBE for the run.

Try going even higher with the agarose concentration, as it looks like you have decent separation of the small bands and poor separation of the large bands. Also try a fresh batch of agarose.
I would suggest trying 2-4% in 0.5% steps
If you are running 100bp or smaller fragments, you should in the range of 4% agarose.
Here is a nice example of agarose ranges and minimum difference of PCR products that can be resolved. https://www.qiagen.com/mx/resources/faq?id=1b23a0b3-32b4-4c1b-bd84-49b4b6a58311&lang=en


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Does drinking water from stainless steel increase hemoglobin?
I'm pretty sure iron molecules will be present in water.
Cooks who use iron or stainless steel pots increase the amount of iron they consume

Welcome to Biology.SE! What research have you done before asking it here?

I'm voting to close this question as off-topic because the answer is found in the article cited.

The article which you cite (which seems accurate and informative) already contains your answer, with a citation for further reading: "Cooks who use iron or stainless steel pots increase the amount of iron they consume. [22]" Iron-deficiency anemia was less common when people used cast-iron cookware. Steel releases much less iron. But food itself  remains by far the major source.

I don't have time to write an answer, but this study examined the effect of cooking in stainless steel and found that it did not alleviate iron deficiency. I imagine that simply drinking water from a stainless steel container would be even less effective. Also I think this is an interesting question.


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What is the energy cost of an action potential?
As I understand it, ions flow down their electrochemical potentials through ion channels during a neuron's action potential. Otherwise, ion pumps work to restore and maintain the resting membrane potential. What is the energy cost of a neuron's action potential? That is, how much work must the ion pumps perform to restore the resting membrane potential after an action potential occurs?

There is a misconception in your question that comes up a lot, most recently here: https://biology.stackexchange.com/questions/62752/purpose-of-k-channels-in-action-potential/62755#62755 The Na/K pump is not necessary for restoring membrane potential after an action potential, it is necessary for maintaining the concentration gradient of sodium and potassium ions over the long term.

Thanks for the clarification. Is it then correct to say that running the Na/K pumps to maintain the concentration gradient are the primary energetic costs of neuron action potential signaling?

Yes, that's correct. The pumps will also have to operate even if there are no action potentials, though action potentials do increase the demand on the pumps. However, so does subthreshold activity: both EPSCs and IPSCs result in ion flow down concentration gradients as well.

There's a few [1, 2, 3] sources that claim it's on the order of $10^8$ ATPs per action potential. The first paper (which is a review that cites the second paper) also has some equations for converting from ATPs to free energy, although that's going to be very context dependent.
If you can't access the third paper, someone has helpfully entered the relevant figures into the bionumbers site.


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What would it take to create life?
Assume we know the right DNA sequence of Mycoplasma Genitalium (MG) and we would like to create Life from scratch.
Also assume that matter has been created and we have the knowledge base as today.
How could we practically or theoretically take such a sequence and create a new MG?
I saw this in case you want to read more:
https://www.quantamagazine.org/first-support-for-a-physics-theory-of-life-20170726/

What do you mean by "from scratch"?

@canadianer given the chemical elements we know today.

You mean chemically synthesize the genome and every other component of the cell?

@canadianer yes, how to create life? Given the Big Bang occurred.

The first step would be a definition of life.

@John how a cell was created at the Big Bang?

It wasn't, there is about 10 billion years between the big bang and the first life. the earth is only about 4.5 billion years old.

I wouldn't say that recreating an organism from a known genome is creating life from scratch.  That would require designing a genome for an organism that doesn't exist in nature.

@jamesqf but except that one condition (i.e. taking DNA sequence information only, of another organism), could we synthesize life from cell-free chemical reagents?

@AlwaysConfused At a minimum you would need some transcription machinery, and probably translation as well (unless you are able to transcribe your translation machinery).

@Bryan Krause: I suppose you might boodstrap things by inserting your created genome into an existing cell, thus using its machinery to create the first new creature.  But I think we're quite a ways from even doing that.

@jamesqf People are doing that; see this answer and the references therein. If memory serves me right, that group is actually working with Mycoplasma genitalium.

@jamesqf Yeah having an entire functioning cell's machinery and just replacing the DNA is definitely the easiest way to go (and the approach people in the field are taking, like canadianer mentions), even if it might be difficult to use a different species' machinery. The problem with simplifying it more than that is even bacteria and archaea have evolved well past the likely initial stages of life back in the putative RNA world. Everything in a cell is highly interconnected functionally.

@canadianer: While that's certainly interesting, I'm not sure that it counts as creating life.  For an analogy, it'd be rather like making a hot rod by stripping all the unnecessary pieces off a car, as opposed to designing & building a car from scratch.

@BryanKrause Is there any instance/ report that human ever made a living cell from absolutely cell-free chemical reagents (even without a piece of macromolecule taken from living sources)?

I am really too interested to know, if (suppose) we are able to assemble atoms from nonliving matter with a hypothetical hand (comparable to laser trap), then would it be able to metabolize and grow just like living cell or it will left there like a dead cell.


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Does starch need to be cooked?
Does starch need to be cooked for human digestion ? Is the answer different for different starches; potato , wheat, corn, etc ?

See the post Can we digest raw starch? on cooking.SE.

I wonder why someone would call this question as "personal health advice"...

I'm voting to close this question as off-topic because duplicate of https://cooking.stackexchange.com/questions/16891/can-we-digest-raw-starch