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What evolutionary reason is there for hemolytic disease?
Nowawadays we have methods which allow us to overcome hemolytic disease of newborn or to prevent it to onset. The Rh or Kell conflict, but how is it possible that it is present? Why it haven't disappear due to natural selection?
A hemolytic disease occurs for example when mother have Rh- and the unborn child have Rh+ after his father. Then when the blood of the child gets to mother circulatory system she creates anti-Rh+ antybodies which will attack and eventually kill her next baby with Rh+. Thus we can assume that hemolytic disease is genetically dependent and cause lethal effect.
So i'm looking for any explanation. I know, that there can be none, i'm just asking.

You should have a look at the post Origin, or source, of rhesus negative in human blood (and eventually at Any evolutionary explanation for human blood groups?)

Disclaimer: I know nothing about hemolytic disease. I would suspect that not all babies of Rh+ and Rh- parents suffer from hemolytic disease. Do you have any reason to think that the variation babies have Rh+ and Rh-
parents to have the disease is due to genetic reason (or in other words, is the disease heritable among the subset of the population of interest)?

Yes, the first baby is "immune" to it, because due to that baby (to be more exacly due to the baby's blood during birth) mom start creating antibodies. If no blood gets to her sistem then there is no problem to the next Rh+ child. But if antibodies exists, then they can travel though placenta to the baby's body and attack him. The Rh is heritable so there is much bigger benefit in having Rh+ daughter. So yes, hemolytic disease as a disease isn't sctictly heritable, but the cause of it is but not as straight as typical genetic disease.

Plenty of undesirable conditions haven't faded away. It's not lethal enough is a reasonable answer, since you already know the genetics.

Hemolytic disease is not a genetic disease. It is a drawback of how the immune system works. In general, the overall benefits of having the immune system as it is right now are way higher than sporadic disadvantages, like the Hemolytic disease, that is why it is not counter selected. If instead of being a rare condition it would be a common one, then I would expect it to be indeed counter selected.

It is genetic. It's connected to the blood heriability.

Well, I would not call it genetic. The mother makes antibodies against the blood cells of the fetus. If the mother is Rh+ and the father is Rh- and the fetus Rh is from the father,  there is a chance of incurring in the disease. But being of any Rh type is not a genetic disease per se. I can't find any gene in the literature linked to the disease itself. But please link any study that suggest the opposite, I am not a master in this particular disease.

"If the mother is Rh+ and the father is Rh- and the fetus Rh is from the father, there is a chance of incurring in the disease"... this is completely wrong.

@GerardoFurtado It was a quick example but please, can you tell me what is wrong?

HD only happens when the mother is Rh-.

I see, I have swapped the Rh signs! The concept stays, it is not correct to call it a genetic disease, it's an immune disease.

You cannot correct a comment after 5 minutes!

just figured that out :)


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Protein/ligand affinity databases?
Is there any database that contain binding affinities reported in litterature for different proteins and ligands?
I have checked uniprot already and it does not seem to included any binding affinity data, for several well characterised receptors such as the human insulin receptor.

You could try this or this. I haven't used either, but searching for a protein that I work with gave disappointing results.

Brenda has a LOT of values from literature than can indicate binding (KI, IC50, Km), but only for enzymes not for proteins in general.

@canadianer I think it just gives binding of (pharmacological) small molecules to proteins. I just searched stat1 to see if it gives the binding energy of stat1 with its receptors. It doesn't. It rather considers stat1 as a target and returns two small molecules. So, I guess there is no good database for binding affinities.

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Have researchers discovered how epigenetic information is passed down during cell division?
For example, how are histone code patterns passed down?
This question was asked a few years ago in this thread:
How are epigenetic marks transmitted during cell division?
However, it has been a few years now, and I'd like to know if researchers have made any progress.
Clarification:
I'm specifically interested in figuring out how chromatin modifications are epigenetically inherited. There seems to be some evidence that it can be inherited, but there doesn't seem to be a full explanation as to how.
A good source for what I'm talking about is a article published in 2010 called: "Epigenetics and the Origins of Paternal Effects", which goes into detail on experiments done on rats that show epigenetic traits being inherited across offspring. However, the article ended on a note saying that the evidence is speculative, and further research needs to be done.  Here's the link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2975825/

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Where do the 2 electrons and H⁺ go when NADPH is turned into NADP⁺ during the Calvin Cycle?
I was wondering where the 2 electrons and H+ go when NADPH is turned into NADP+ during the Calvin Cycle? I know that during the light dependent reaction, 2 electrons (from water) and H+ combine with NADP+ (from the Calvin Cycle) to form NADPH, but after NADPH is used and is turned into NADP+, where do those electrons and H+ go?

where have you looked for this answer?

@VanceLAlbaugh my biology textbook. It does not have any information on it.

This is quite basic in a photosynthesis class: they are used to reduce the 3-phosphoglycerate to glyceraldehyde-3-phosphate.

A reasonable source of information about the Calvin Cycle is Berg et al., but for this reaction the full structures are not shown. I therefore show them below in a diagram of my own:

I have coloured the hydrogen atoms to show where they go in reducing the phosphoglycerate (acid) to an aldehyde. You can think of the two electrons being used to form the additional covalent bond.
(The hydrogen phosphate is actually in equilibrium with other phosphate species, but this is not relevant to your question and so is not shown.)


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What is the name of this herb plant?
I found it outside in the City of South India in the month of May.

Another view:

That will be easier if you have pictures of the flowers and/or fruits. If you open the fruits, you may increase your chances even more.

@Rodrigo I think it is non-flowering & fruitless plant.

I think it is an ornamental plant.

By the shape of the leaf, it surely has flowers and fruits. In the picture above, to the left, it looks like a bunch of Piperaceae fruits.

@Dhanraj Kumar All monocots and dicots flower and set seed even if you don't notice them.

@Dhanraj Kumar What size are the leaves? Are the stems round or square in cross section?

No guarantee that my answer is the right one but my educated guess that your plant is a species of Acalypha. There are a number of species in this genus and I'm sorry I can't narrow it down further.
The shape of the leaves, the little 'pig-tail' shaped seed (or unopened flower) spike seen in the upper left corner of the first photo, the tinge of pink on some leaves and veins and even the twist or curl on the uppermost group of leaves leads me to think that.
I'm including some photos showing these points. Whether it's a plant in this genus is for you to decide. It would be helpful to know the size of the entire plant and he range of size in the leaves.
Acalypha wilkesiana

Another Acalypha wilkesiana with this one showing the 'pig-tail' flower spikes better.

The flower spikes are very evident in this Acalypha bamentacea here.

The twists and curls can be seen in this cultivar of Acalypha wilkesiana.

Source courtesy of Dave's Garden

It looks vaguely hibiscus-esque, but it looks like you either have a chimera or a disease going on that makes identification difficult.  The leaves in the center of both pictures do not look characteristic of the species when compared to the leaves on the edge of the photograph - the stems have lost their apical dominance and the leaves are curled and have lost their conformality.  That speckling may be purposefully bred for a horticultural variety, but if it's not, it may be a symptom of whatever is causing these other troubles.

Hello, could your support your answer with online references. Supporting answers with credible references is a best-practice on Stack Exchange.


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Spider identification: male black widow?
Unfortunately I didn't snag a picture but I found a small spider with reddish legs and enlarged fangs in Victoria, BC, Canada. The spider was very quick and looked similar to pictures of male western black widows I found online. The difference was that the spider I found had a light brown body but pictures I found online typically had white stripes.
Is it likely the spider I saw was a Western black widow or are there other species that look similar in this region?

I think it's unlikely.  Without a photo, it's hard to be sure of anything, but Black Widows don't have reddish legs or enlarged fangs, and it's hard to think of any circumstances in which they could be called "very quick".
Your description might fit a spider called Dysdera crocata (here's a link: https://bugguide.net/node/view/3388 ), but that's purely a guess on my part.
The problem with trying to ID something from photos when you're not very familiar with it, is that you may not be sure what to look at to distinguish it.  If you can't get a photo, make sure you include the most detailed possible description, including anything about it, no matter how seemingly insignificant.  What it was doing, where it was, etc., etc.


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Why did viruses evolve in the first place?
This question might seem kind of strange, but it's something I've been chewing on for ages, and I can't really think of a good answer.
Viruses just seem to be floating around passively until they encounter a host cell. Then they enter the host cell, wreak havoc and use the host cell machinery to make more copies of themselves. Then these copies float around passively, until they find host cells.
So what's the point of all this? Infecting the host and causing so much trouble for the host, I mean. The only thing I could think of was something like the "selfish gene" hypothesis, i.e. the genetic material of the virus wants to make as many copies of itself as possible, and in order to secure the machinery for replication, it must infect a host cell. But it's not a very satisfying answer, somehow. All other living organisms at least have their own replication machinery. Then what kind of organisms are viruses? (Are they even organisms?) How and why did they evolve and stay around on the earth for so much time (till the present), if they depend on hosts for their replication?

The simple answer to why anything in biology happens is always: "Because it works". As long as a thing is able to replicate itself, it will do so. Viruses have found many different ways of getting replication to work, and so they continue to replicate until one day it doesn't work anymore (like it should have been the case for poliovirus a long time ago).

They float passively until they encounter the right conditions, the same could be said of any spore or seed. The point of viruses is to make more viruses, the point of any biological product is to spread the genes that created it.

I don't really think there's a point to anything. Things just happen, and we try to understand how things happen, and the consequences of things happening. Everything you do and think is only but the result of some chemical reaction. Just like how everything a virus does is nothing but the result of some chemical reaction. I do however believe that viruses are a beautiful example of self-preservation. Viral DNA/RNA truly is the most well adapted in terms of finding a way to continue replication.

The are different theories about virus evolution, some speculate that they were evolved before the cells, some speculate they are evolved to spread genetic information, a sort of specialized conjugative pilus others say that they are cellular parasites. Still, none has the final answer yet, but thanks to the boost of DNA sequencing, many new pieces of the puzzle come out lately so keep updating your knowledge!
Whether they are alive or not is also matter of discussion and it pretty much depends on the definition of life itself.
If you define life as the property of reproducing, transmitting genetic information and evolve, then viruses are life forms. But if you want to include in the definition that a life form must have all the biomolecular machinery encoded in the DNA (I really disagree on this point), then they are not. To me, they look quite a living thing.
About your sentence:

So what's the point of all this? Infecting the host and causing so
  much trouble for the host...

I think you are looking only at the "negative" side. Viruses can transfer useful genetic information, plus they are involved with the evolution itself. We humans have lot's of viral DNA in our genome, so no viruses, no humans as we know them. Think about it ;)
There are plenty of resources around to get a better insight please have look at the following links to get started.
https://en.wikipedia.org/wiki/Viral_evolution
https://en.wikipedia.org/wiki/Evolution_of_influenza
http://www.sciencedirect.com/science/article/pii/S0042682215000859
https://link.springer.com/article/10.1007/s00239-013-9601-0
https://www.nature.com/search?order=relevance&q=evolution%20of%20viruses

I think you are looking only at the "negative" side. Viruses can transfer useful genetic information, plus they are involved with the evolution itself.  Downvoted because of this profoundly misleading sentence which suggests that there's a goal to evolution, and that organisms "should" only evolve if they have "good purposes".

@iayork Where do you read this exactly? I did not suggest any goal whatsoever. I just suggested that there are positive effects of virus infections, including broader secondary effects like humans evolution. My sentence was meant to point out that you have to consider the variety of effects, not only the "negative" one. But definitely, there is no suggestion of any goal or a "good purpose".

My sentence was meant to point out that you have to consider the variety of effects, not only the "negative" one.  Exactly my point; that's a profound misunderstanding of evolution.

@iayork how can be misleading something like "consider the variety of effects". I really don't get you...

The fact that you don't understand my point demonstrates that you don't understand evolution.

That's definitely not a mature nor scientific way of putting it.

Some folks like mimat get a bit pedantic. "Viruses are not life because we've defined life in such a way that viruses are not alive". Circular reasoning much?
The ocean contain something on the order of 10-15 viral particles for every bacteria. Viruses are clearly an integral, if less-understood, part of modern ecosystems. The question of where they came from, and how they relate to the other domains of life (bacteria, archaea, eukarya) is an interesting one to explore, if unsatisfying because we don't have a lot in the way of answers.
Why do humans exist? From our genes' perspective, we exist as replicative machines whose primary function is to make more of our genes, enabling them to exist in perpetuity. It's the same with viruses. They exist because the mechanism of viral replication is effective at making more bits of viral genetic information.
Asking 'why' something arose in the first place isn't a very useful way of phrasing. Mutation in evolution doesn't occur with foresight, instead it's the random element of evolution. (Natural and Sexual Selection being totally non-random.) Asking 'how' is a better question.
Thinking about viruses not being alive because they lack the ability to make everything they need for replication. This is more than a bit pedantic: are then humans not alive because we lack the ability to make some thing we need (vitamins)? Viral capsules are machines built by genetic sequences that allow those sequences to replicate in perpetuity - same as us. I certainly think they're a form of life, and like almost all other life, they are dependent on existing in an ecosystem with other forms of life.
As to where life came from, or a particular type like viruses, very interesting question. LUCA, or the last universal common ancestor, has been inferred to have been a protocell using something like methanogenesis or acetogenesis, had a cell membrane, and either DNA or RNA for storing and replicating genetic information. Going earlier in time to the RNA world gets interesting.
Think about a given genetic sequence. While any given instance is transient and fragile, there may exist billions of copies of it at any given time on earth. An exact copy of that sequence may have existed for hundreds of thousands of years. Inexact copies for millions, and if you are generous and think of gene families, genes may have lifetimes measured in billions of years.
Microbes are far more 'promiscuous' with their sharing of genetic information than we usually think about, as multicellular organisms. You could think of microbes as systems that are very flexible, while multicellular systems have traded that adaptability for in-system optimization. That is, to us viruses make us sick, but to a bacteria a plasmid or virus might be costly, but potentially advantageous if it brings with it new, beneficial genetic information.
Viruses could be thought of as a super-spore. A spore is a dormant, but very tough capsule that allows its parent genetic sequences to survive hostile times, and then resume metabolism and replication when better times or environments come. To a virus, every environment is a hostile one except the insides of their specific target cell. In a way, you could think of a virus as 'sleeping' or dormant until it enters a host cell, and only truly active or alive when it is. Think about the actual genetic information as the 'alive' entity, and anything constructed by it as a machine.
Viruses probably predate LUCA.
Time to get super-super-speculative.
Among many ideas as to how life arose, in particular cell membranes, one hypothesis is that early cell membranes arose abiotically. According to this notion, life only gradually gained the ability to modify and eventually synthesize membranes. The original membranes may not have been composed of modern stuff at all, as long as it performed the essential functions of being a selectively permeable barrier. Early oceanic vents provide a place where protomembrane molecules could have been abiotically generated and condense on porous rocks.
Likewise, there is a question as to what came first, or if this is a good question: metabolism or genetic information replication. How do you have one without the other? Well, again, early oceanic vents seem a good candidate for abiotic metabolism to have begun building precursor molecules. Get a precursor molecule with the ability to make something like it, and voila: replicators! Personally, I think the order is this: replicators first and gradual control of metabolism and cell membranes later. You could almost think of metabolic machinery as simply being the means of recreating the conditions that existed in those early vents, or the porous rocks around them: conditions that enabled replicating machinery to replicate.
Who knows if this concept is true! But if something like this is how life got started, then at some point before luca, the original replicator more closely resembled a virus as it exists inside a cell, than it resembles modern cells. If replicators in their early days lacked much control over metabolism and/or membranes, that kind of sounds like viruses. Before early life 'took off' in its modern cellular state, early genes needed to connect with other genes for replication, but not necessarily for distribution. Maybe this took the form of physical connection via protochromosomes. Perhaps branches of genetic life that became many viruses opted for an alternate strategy.
Multiple genes that are located on the same chromosome (circular or linear, doesn't matter) have opted to link their evolutionary futures as closely as possible. They are literally, physically linked. The link may not be physical: our genes, even if located on different chromosomes, still have linked fates, marred only by recombination and sex. Remember that microbes are much more fluid and genetically flexible. From a gene's perspective, a cell is simply a location with other friendly genes, which which the 1st gene shares an evolutionary trajectory. If the 1st gene happens to be on a plasmid, however, its fate might be more independent, as copies get swapped into other cells. Microbes have many ways of swapping genetic information. To the extent that this information can be swapped around, the evolutionary future of those swapped bits is less dependent on the exact nature of the other, more cellular bits. Viral genes have opted for an even more independent evolutionary trajectory than plasmids and similar structures. I mean, really, what eats a virus? They build themselves protective capsules and are only really vulnerable when they are inside a host cell and actively replicating. If I were a genetic sequence with billions of physical instances at any given moment, and potential information lifespan in the billions of years, that honestly doesn't sound like a bad way to replicate.

Welcome to Biology.SE and thank you for your comprehensive and expansive answer. Could you maybe add some reference to your claims (peer-reviewed literature is preferred, Wikipedia etc. is very much okay for common knowledge) - this allows others to follow your arguments and increase their understanding by further reading. Please also consider taking a look at what is considered a good answer on this site and take the tour. Thank you!

Viruses are not considered alive because they cannot reproduce independently and are therefore not organisms.
As to the answer to 'why' something arose in evolution is always the same: because at that moment in time this specific set of traits was able to function and create a lot of offspring (or copies). The virus 'might create a lot of trouble for the host' but that does not matter, a lion causes a lot of trouble for antelopes but that does not get questioned.
Evolution as a process is not teleological, nothing evolution does has a purpose or end goal, a combination of traits simply works better than what came before in a specific set of circumstances.
You already mentioned the selfish gene hypothesis, in my personal opinion that is the best explanation.

Viruses actually have RNA. Due to this property of genetic material, RNA organisms are faster than DNA organisms!
Secondly, they have a protein coat that acts as another important thing which makes allows them to live in contact with organisms!
But every coin has two sides. It is much used in biotechnology to transfer important genes in plants and animals by disarming their pathogenic properties!
When they come in contact with host DNA, host DNA starts to replicate its virus genetic material and then its own! For example, in the case of HIV.

See in the image how reverse transcription the most important process converts RNA -> DNA then creates an infected DNA strand in host and host produces its RNA which is infected!

Hi Welcome to Bio.SE! Please provide some support for you answer to avoid having it downvoted or closed. Supporting answers with credible references is a best-practice that we have come to expect on this Stack Exchange site. Thanks!

Your answer doesn't seem to answer the question. Please edit your answer to avoid having it downvoted/removed. See here for a guide to writing good answers.  ... Also, I tried editing a bunch of your answer to try to improve grammar, spelling, punctuation, etc. I hope that you use this as a learning tool to create higher quality posts of your own in the future. Thanks.

There are a lot of factual errors in this answer, you have both RNA and DNA viruses and these have little to do with speed. Naked viruses do not have any proteins so that is also wrong


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How does heart beat faster while doing a strenuous task?
I know that when we do tasks which require extra physical effort (like running etc.), our heart beats faster.
I also know that the reason behind this is that these jobs require more energy than usual and, hence, require more oxygen for breaking down food. And, since, oxygen is transported throughout body by blood (by forming compound with Haemoglobin (present in RBCs), called Oxyhaemoglobin), the heart needs to beat faster to pump more blood.
However, I am not aware of how does the heart automatically start beating faster.

Is there any involvement of the Nervous System?
Does the heart have some sort of special mechanism that activates when the body performs a strenuous job?

What research have you done before asking it here?

I am sure that there are many ways that your body can regulate heart rate, but I am going to cover this topic briefly from the perspective of $\ce{CO2}$/$\ce{O2}$ concentrations, and pH.
The medulla oblongata
The medulla oblongata is part of the central nervous system, and makes up the lower portion of the brain stem. It is responsible for performing autonomic functions, including the regulation of heart rate through chemoreceptors. The medulla oblongata receives its blood supply from the vertebral artery and makes both afferent and efferent connections with the vagus nerve.
Chemoreceptors
There are two main types of chemoreceptors in your cells that are responsible for regulating heart rate.

Central chemoreceptors

These are located in the medulla oblongata, and are responsible for measuring the concentration of $\ce{H+}$ ions (ie. pH). When the pH is low, neural cells with these receptors will signal the release of norepinephrine and epinephrine.

Peripheral chemoreceptors

These are located in the carotid and aortic bodies and measure the concentration of $\ce{O2}$. The receptor cells of these structures make connection with afferent nerves, to send a signal to the central nervous system in times of hypoxemia.
$\ce{CO2}$/$\ce{O2}$ Exchange
Blood is the tissue responsible for distributing chemicals around your body. It is therefore also involved in the $\ce{CO2}$/$\ce{O2}$ exchange between tissues. Blood cells use hemoglobin as as a carrier molecule for this exchange.
When $\ce{O2}$ is delivered to tissues, it will be processed by the mitochondria of the cells to synthesise ATP, and $\ce{CO2}$ as a biproduct. ATP is also responsible for muscle contractions, and so, with exercise comes an increased utilisation of ATP. With ATP stores running low, your cells will begin to use more $\ce{O2}$, and therefore, they will produce more $\ce{CO2}$.
$\ce{CO2}$ and Acidity
So, I kinda lied when I said hemoglobin is the carrier of $\ce{CO2}$. This is mostly true, but $\ce{CO2}/$$\ce{O2}$ is also somewhat soluble in blood, and this accounts for changes in blood-pH.
$\ce{CO2 + H2O}$ $\ce{<=>}$ $\ce{H2CO3}$ $\ce{<=>}$ $\ce{HCO3- + H+}$
The above equilibrium is catalysed by carbonic anhydrase, and accounts for a decrease in pH levels.
Signalling in response to pH
So your exercising, your body is using lots of $\ce{O2}$ to produce ATP. Your $\ce{CO2}$ levels have increased, and your internal pH has dropped. Now what?
Well, as I'm sure you have guessed, your nervous system takes over.
The central chemoreceptors of the medulla oblongata send an impulse to  the adrenal glands in response to the decreased pH. This signals the release of the hormones epinephrine and norepinephrine in to the bloodstream. The release of epinephrine and norepinephrine is regulated by the sympathetic nervous system. This accelerates the heart rate by binding β-receptors in your heart tissue. Efferent nerve connections from the vagus nerve also participate in this process (I think).
For mechanisms on heart contration, see here; everything following "excitation contraction coupling" is probably the most relevant.

I think this answer is good and very extensive. However, I didn't immediately see the (important) aspect that all these measures are transfered to the heart via the sympathetic nervous system. Since the OP specifically asked for involvement of the NS I suggest adding a disclaimer stating this involvement to the top of your answer.

I am guessing from neural cells and @Nicolai 's comment that the involvement of the Nervous System is there. Am I right?

@Nicolai Thank you for your suggestion. I have edited my question. Does this seem better? And yes Arjun, of course! But, I think it is more interesting to know what it is exactly that elicits the nervous system's involvement in a function.

@Arjun Yes, I think this way it's much clearer where the different receptors are and how the signal is transferred to the heart

Whenever we think about our body changes, we have to think what come first, what is cause and what is effect. How the heart automatically start beating faster?

In short, whenever there is role of controlling mechanism, neural and humoral used to get involve. Paraventricular nucleus of hypothalamus controlling the medulla autonomic nervous system. While resting vagal tone is inhibited, sympathetic predominates leading to positive chronotropic and inotropic effect. Emotional and other factor also involve. Even anticipatory effort can have the effect. Humoral is through hypothalamo-hypophisial-adrenal medullary axis.

Thank you for your answer and welcome to Biology.SE. Could you back up your answer with references? Thank you!

Whenever we think about our body changes, we have to think what come first, what is cause and what is effect. How the heart automatically start beating faster? For this question, blood gas changes come later which is the effect of physical activity that will regulate heart rate further. All the senses visual, auditory, touch etc even the act of thinking physical activity will increase heart rate. Our body has extensive feedback system, in preparation for body need. So many references are there. I used to refer Ganong physiology review.


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Flow Cytometry to learn about Cell cycle
I am posting my Flow Cytometry data here again because I realize that there are many people who are willing to help me, and I can learn a lot from you guys.
In this cell culture Lab, we use Cell U-937 Lymphoblast. And we want to learn how can we analyze cell cycle by using flow cytometry.
Could anyone help me to explain how to read the flow cytometry result related with cell cycle? I will be very glad to learn from you guys.
Thanks in advance!

The basis of analysing flow cytometry data in regard to the cell cycle is the fact that DNA synthesis occurs in S-phase and therefore cells before S-Phase (G0/G1) have half the amount of DNA compared to cells after S-phase (G2). [M-phase lasts to short to be of any relevance for this kind of analysis]. Signals that have less DNA than the cells from G0/G1 phase are either artefacts or apoptotic cells with fractured DNA (these are labelled as sub G1).
In order to measure the amount of DNA per cell the dye PI (propidium iodide) is used, since its quantitatively binds to DNA. Therefore the distribution of the PI signal can taken as a distribution of the different stages of the cell cycle.
This wikipedia article also explains the analysis in more detail and provides further references.

Thanks for your response! And may I ask what represent the 100% Sub G1 in Unstained control? Is it also dead cell? or just a population of cell before undergoing cell cycle? @Nicolai

@Sokviseth In an unstained sample none of the PI dye was added. Therefore you can not detected any DNA in these cells (even if it's there), so you can not say in which part of the cell cycle they are. This control is only done to check for problems with the PI staining.

Ah, I see :-). And i wonder one more thing why the amount of cells in (Dot Plot diagram) None is lower than that of Rapamycin (87.8 Vs. 91.4). Since the Rapamycin can inhibit the cell cycle, why the amout of cells do in crease? @Nicolai


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HapMap 3 phased haplotype
I need to get HapMap 3 phased haplotype data. Where can I find it?
Actually I need these data for specific populations and a specific gene. What is the easiest way to find data?
I hope I can find an answer. Thank you!

Here is the FTP address. Inside you will find the phase_3 folder. For other questions check this page (the link to the HelpDesk is at the bottom of the page).

Thank you for your quick answer. I used following command for this file tar -jxf hapmap3_r1_b36_fwd.qc.poly.tar.bz2 . But I don't know how can I get haplotype data for ± 1 Mb at LCT gene from this file. Actually I need a data file which include sample ID and alleles to use in R.

That is another question and it is a bioinformatic one, maybe StackOverflow or Biostars are more suitable for that.


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Is this a young Ash Bud Moth (Prays fraxinella) caterpillar?
I am building up a my knowledge of organisms that live on trees (not necessarily as pests, but in the respect of the biodiversity that depend on different tree species) and their interactions.
Living on the underside of Fraxinus excelsior, in northern Europe (N. France), I have found these tiny caterpillars (end of May/start of June). They are eating small patches of the leaf, and excreting black frass.

The ash leaf in this photo is 70 x 35 mm, and so the caterpillar shown in approximately 1 mm in length, but there are others up to 2 mm.
The photo above also shows the mines in the leaf.
Under a hand lens, the body is an opal/beige colour and it has two black patches on the body above the head. The body is very shiny and glossy and it looks wet.

From my internet research it looks like a young caterpillar of the Ash Bud Moth (Prays fraxinella)?

I probably need to invest in a good macro lense for my camera

Since nobody seems to answer your question, I think you need to wait for another week or two. They will eventually mature and it will be easier to identify them.

Yes thanks, I am keeping an eye on them and will track their progress. I already have a photo of one twice the size which I can add to the post.

Every time you add a picture, your question is modified and it gets bumped up on top of other questions. If you have many pictures of you lovely green creature, don't post them all at once, add one picture per day. This way more people will be able to view your question and sooner or later somebody will be able to answer it.  Just a helpful tip.

Stereonychus fraxini (De Geer, 1775)

Well, that would explain why after returning from France to the UK, I haven't been able to find the larvae here. Perhaps this species has no yet made it across to the UK? I am familiar with ash bud moth, so I would have expected to find the larvae here. Interesting though how the Wikipedia Prays fraxinella caterpillar looks like an older version of the Hungary Forestry Institute images they name Stereonychus fraxini. I'd probably ere on the side of the latter, and agree with you. But yes as @theforestecologist says it would be good to provide some sources to back up your answer please.

I have been doing some further looking into this and came across a video of Prays fraxinella, feeding as a leaf-miner https://www.youtube.com/watch?v=LqL6LKEg05k&feature=youtu.be linked from this page http://www.ukflymines.co.uk/Moths/Prays_fraxinella.php so yes, this increasingly looks like Stereonychus fraxini


text:
Meaning of "U" in "Viral Protein U"
What does U mean in Viral protein U?

Viral protein U (Vpu) is a unique gene product of human immunodeficiency virus (HIV) type 1 (HIV-1) with two well-described functions...

So does U in this case mean unique?

Source: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC114397/

So does U there mean unique?

No. The name of the Viral Protein U comes from the names of the Open Read Frames (ORFs) of the Visna lentivirus, termed by Sonigo et al (1985).
According to the paper that actually named the Vpu (Strebel, Klimkait and Martin, 1988):

In this study, we show that another small (81 codons) HIV-1 ORF, designated vpu ["U", see (2)] encodes a 16-kD protein that is expressed in vitro and in vivo. Mutagenesis of vpu in an infectious molecular clone of HIV-1 results in the synthesis of particles with altered replicative capacity.

If you look at that reference number 2, you will find a paper named Nucleotide Sequence of the Visna Lentivirus: Relationship to the AIDS Virus, from Sonigo et al. (1985).
In that paper you will find several ORFs, named F, Q, R, U3, U5 etc. Why are they named like that is another question, but it seems to me that they are just letters of the alphabet, with no meaning. Vpu was named because of U3. By the way, HIV also has a Vpr, because of the ORF R.
Sources:

Strebel, K., Klimkait, T. and Martin, M. (1988). A novel gene of HIV-1, vpu, and its 16-kilodalton product. Science, 241(4870), pp.1221-1223.
SONIGO, P., ALIZON, M., STASKUS, K., KLATZMANN, D., COLE, S., DANOS, O., RETZEL, E., TIOLLAIS, P., HAASE, A. and WAINHOBSON, S. (1985). Nucleotide sequence of the visna lentivirus: relationship to the AIDS virus. Cell, 42(1), pp.369-382.

I thought that R is for replication, because Vpr is required for virus replication in non dividing cell like macrophages. Thanks for it too.


text:
Which kind of bird is in the picture?
I am wondering what kind of bird this is. Can you help me?

It is a male Rufous Whistler (Pachycephala rufiventris).

The species is sexually dimorphic. While females are typically dull brown or grey with streaked underbodies, males are predominantly dark-grey with white throats and (in most cases) a black mask that covers most of their head and some of their neck.

Your picture is from : hbw.com.


text:
How do the three mechanisms of the 1000X improved "new" vancomycin work together?
The BBC News article Ultra-tough antibiotic to fight superbugs says (in part):

One hard-to-treat infection that has been worrying doctors is vancomycin-resistant enterococci or VRE.
It has been found in hospitals, can cause dangerous wound and bloodstream infections and is considered by the WHO to be one of the drug-resistant bacteria that pose the greatest threat to human health.
Some antibiotics still work against VRE, but the 60-year-old drug vancomycin is now powerless.
The Scripps team set out to see if they could revamp vancomycin to restore its killing ability.
They made some strategic modifications to the molecular structure of the old drug to make it better at attacking bacteria where it hurts - destroying cell walls.
Three changes in particular seem to be important, increasing the strength and durability of the drug.
Lead researcher Dr Dale Boger explained: "We made one change to the molecule vancomycin that overcomes what is the present resistance to vancomycin. And then we added to the molecule, two small changes that built into the molecule, two additional ways in which it can kill bacteria. So the antibiotic has three different, we call them 'mechanisms', by which it kills bacteria. And resistance to such an antibiotic would be very difficult to emerge. So it's a molecule designed specifically to address the emergence of resistance." (emphasis added)

Unfortunately I haven't been able to see the PNAS paper. The link in the BBC article just gives me this:

However the title in PNAS seems to be stated in the Genetic Engineering & Biotechnology News article Vancomycin Modified to Combat Growing Antibiotic Resistance Threat as "Peripheral Modifications of [Ψ[CH2NH]Tpg4]Vancomycin with Added Synergistic Mechanisms of Action Provide Durable and Potent Antibiotics"
It sounds to me that the first change was to keep the original vancomycin's original mode of action but to make it more robust against adaptations in the vancomycin-resistant strain, but I'm not sure if that's correct.
The other two differences sound to me like two new mechanisms that were not there before - it almost sounds like they could just as well be on different molecules administered simultaneously, and that their presence on the vancomycin molecule is primarily for issues of delivery.
Are these two new changes essentially independent modes of actions that could be on separate molecules, or do they need to reside on the same molecule as the primary mechanism?
The article puts the word "mechanism" in quotes. I'm trying to understand if these are independent or work together at the molecular level - in other words do they operate together in such a way that they need to be on the same molecule?

Unfortunately we have to wait until this paper is published and then see what the exact mechanism and the modifications are. My guess is that they chemically modified Vancomycin, but this can be wrong.

@Chris Oh, so it is not just me - nobody can see the paper yet? I thought it was just paywalled. I can't see how "They made some strategic modifications to the molecular structure..." could be interpreted in any other way than "chemically modified".

You can't see this paper unless you are a registered journalist. It is still under embargo until it is released - journalists only get access to it to get some more publicity. But I found some interesting information, I "only" have to write up the answer...

you can find some information about it on the "In the Pipeline" blog from Derek Lowe (http://blogs.sciencemag.org/pipeline/archives/2017/05/30/antibiotic-progress-and-not-a-moment-too-soon), but the link there also fails for me, so it looks like the embargo date is wrong for some reason.

@Chris et al. This seems related; same research group, but published a few years ago http://pubs.acs.org/doi/ipdf/10.1021/ja507009a

@MadScientist The blog is interesting reading, certainly some clues there at least. "...and in this new work they’ve got a compound that combines greatly improved potency with three separate mechanisms of action."

Since PNAS comes out weekly, my guess would be that the article is included in the issue which comes out today or the one next week. I will have a look at it.

@Chris thank you for your attention - I will "stay tuned."

Answer updated. :-)

This is typically for a paper under embargo - it can be accessed by registered journalists so they can cover the original article when it is published. The paper is now published, so I changed the first answer.
Before I go into the details, it is necessary to have a short look at the working mechanism of Vancomycin and the way bacteria got around it (which took exceptionally long given that the drug is used since 1959 in the clinic):
Vancomycin works by inhibiting the proper crosslinking of the bacterial peptidoglycan in the cell wall. This is achieved by binding to the substrate for the peptido glycane synthesis, a D-alanyl-D-alanine end of a peptide. Cells then burst due to osmotic pressure.
Resistant cells have a D-alanyl-D-lactate ending of this peptide (all details can be found here or in the introduction of the paper) which lowers the effictivity of the drug by a factor of 1000. Interestingly, this resistance mechanism seems not to have evolved in pathogen bacteria itself, but has been "borrowed" from bacteria which produce Vancomycin and need this as a self-defense (for more, see reference 2).
Vancomycin forms a pocket around the d-Ala-d-Ala substrate, which is impaired in the resistant form. Overcoming the resistance means finding a variation of Vancomycin which effectively binds both of the variants and thus inhibits proper cell wall crosslinking.
To achieve this, Okano and his colleagues chemically modified the structure of Vancomycin with several different functional groups at different sites of the molecule, see this figure from the paper (figure 4 from reference 1):

Changing these residues changes the sensitivity against these modified Vancomycine quite a lot, as can be seen in the sensitivity table in the figure.

When they changed the molecule, they did not only change the binding pocket to allow binding to the different peptide substrates, they also introduced two other independent mechanisms against the bacteria. The most active compound (named 18 in the paper, seen above from figure 11) shows:

Compound 18, which incorporates the redesigned pocket modification for
  dual d-Ala-d-Ala/d-Ala-d-Lac binding (blocks cell wall synthesis by
  ligand binding, including inhibition of transpeptidase-catalyzed
  cross-linking), the CBP disaccharide modification (blocks cell wall
  synthesis by direct transglycosylase inhibition without
  d-Ala-d-Ala/d-Ala-d-Lac binding), and the C1 quaternary ammonium salt
  C-terminal modification (induces membrane permeability), exhibited the
  most potent inhibition of cell wall synthesis in the assay of all
  compounds assessed.

Okano and colleagues also tested the different modifications one by one to see, which one has which effect and also tested the effectivity on resistant bacteria. The resulting table shows that the strongest effect is only achieved when all three modifications are present in the molecule.

Since these are independent mechanisms, it will also prolong the time until resistance against the new version of Vancomycin (given that is has a tolerable toxicity in humans and can be introduced into the clinic) will take a while to develop. Despite the optimism in parts of the paper this resistance will eventually develop, although it is quite complicated to overcome three different mechanisms.
References:

Peripheral modifications of [Ψ[CH2NH]Tpg4]vancomycin with added
synergistic mechanisms of action provide durable and potent
antibiotics
Glycopeptide antibiotic resistance genes in glycopeptide-producing
organisms.

My goodness! Did you have this already written and ready to go? This was quick, thanks! Certainly helps to have further reading. It will take me a while to read these. In the mean time, it it  likely that these changes must all be on the same molecule to work together, as compared to simply dosing with three drugs, each with one of the changes?

+1 I don't get to read papers like this anymore, so it was a refreshing answer. Now the cynical me wonders how many more thousands of times more expensive this new and improved vancomycin will cost to use. :-/

@uhoh Nope, I looked this up. Googling the the compound named helped, finding and pinning down information is critical and something I learned over the years in research :-) Plus: This topic interests me, so I read about it every now and then.

@anongoodnurse We haven't reached the clinics yet - but my guess (driven by my experience in the costs of the new cancer therapies) is also that this will be expensive.

@Chris - Sorry, a side question: I would guess this is all in vitro antimicrobial testing. Do you know if any in vivo testing for toxicity has been undertaken? It seems to me that would have been considered in developing this drug before releasing the information that there's a new vanc in the works.

@anongoodnurse I don't know, but I can have a look. It is probably also in this embargoed paper...

Thanks! Don't go to too much trouble, tho; it's really not in the OP's question. :)

@anongoodnurse It certainly may be in there to a trained eye, but I don't see "they have to all be on the same molecule" or "they could be on different molecules." If I say that I need some clarification, why not take it in good faith and help me understand?

@anongoodnurse I think you can say "if we want to decrease hemoglobin's affinity to CO, do we need to add some other molecule to it? No, you need a modified version of hemoglobin OR would just putting in a modified version of hemoglobin completely solve this? No, you also need to modify the molecules already in there". Maybe this won't work either (or maybe its just my lack of confidence :P)

The paper is out now and they use the components mentioned above. I will update the answer tomorrow. @anongoodnurse They mention no lytic activity against RBC, and also see no growth inhibition in cell based assays. Animal experiments as well as toxicity and tolerance studies in humans of course need to be done, but it looks pretty much like there is not much toxicity.

If I follow correctly (I could be wrong, I have primitive knowledge of ochem) the logic is something like this: protein binding is like fitting together two complicated jigsaw pieces, if they don't fit together properly they don't bind.  Binding to part of a molecule only works if there's a "space" and potentially produces other issues besides.  You could have two molecules to bind to the two types, but why not have one molecule to do it if you can get away with that?

@Kaithar This is exactly the problem. Getting Vancomycin to bind the actual two possible structures and prevent the crosslinking.

Thank you for the update! I'll head to the library and take a look in the next few days. It seems one can be exposed to a number of different concepts and issues from this particular example. So for example, the mechanism related to the CBP disaccharide modification also has antibiotic activity, and there's nothing in the paper that says it necessarily has to be on the same molecule as the other modifications, is that correct? The mechanisms seem to work independently and it's more of a convenience to put them on the same molecule versus a "cocktail" of one-at-a-time modified variants?

@uhoh The different mechanisms work independently, and it makes the component more potent. The 1000x more activity comes from the combination of all three. Nevertheless, the other two (not the substrate binding) could be of interest in similar antibiotics.

@uhoh - I finally realized what you were asking! I'm so sorry I misunderstood.

@anongoodnurse no problem! Through itteration and patience, stackexchange can make amazing things happen :)


text:
Why is a DMSO-only Control Important?
Why is it necessary to have a DMSO alone control when DMSO has been used as the solvent (vehicle) in the treated conditions?
And, in this case, why is the viability of the untreated condition lower than the vehicle (DMSO alone)?

It could simply be that the reagents or drugs involved dissolve well in DMSO and poorly in other solvents. Vehicles are a way of saying this is the drug/reagent + solvent. As always, when DMSO is the solvent, include DMSO-alone controls so you know the effect you're seeing isn't a result of the DMSO.

@CMyosychuk So we use it in order to know whether the drug or reagent itself that has effect on cell viability, right? And based on the above graph, why do the graph of Vehicle is higher than None?

@Sokviseth Its not possible to give a clear 'why' answer to that question. The most probably reason is just biological variance, from your two different samples. Also note that the SD (which doesnt make a lot of sense for 2 samples anyway) for the vehicle control is very large.

As @Nicolai said, this is most likely simply variance, with more independent samples, the difference will probably be smaller. Additionally, given these error bars, I would see the untreated and the DMSO samples as the same. The treated samples are pretty much different from them.

@Sokviseth What's your measure here (the axis values)? If it's indeed a measure of viability, basically you're saying your drugs are dissolved in DMSO, and you want to see the effect of the drugs vs. no drugs. But, the DMSO can affect viability, too, so you have to do a DMSO alone condition. Your goal, however, is you actually want to say that the DMSO had no effect so you can see the pure effect of your drugs. The p-value between your none and vehicle is like 0.5, which means they aren't different, which is good because your drug readouts will have no/little background.

In my opinion, you want to get a third replicate though to give yourself the best statistical power, and make those error bars a little tighter.

I edited the question so it may be reopened

@CMosychuk Why do you think this question should be reopened? This is a pretty simple homework-style question.

@CMosychuk Thanks for your explanation :-)  I learned a lot from you!

@BryanKrause Every question should be welcomed. It is might be simple for you, but it is not for someone else. I just need to get some ideas from this forum. :-) Science is about discussion.

@Sokviseth The reason for the prohibition on homework questions is that homework is designed to direct your learning, and asking on SE bypasses the normal ways to obtain that information. A lot of what you are supposed to be learning about is actually how to obtain the information, not just obtaining the information itself.

@BryanKrause The way I worded it in my edits probably made it more homework than it is. To the layman, seeing a DMSO control in a scientific figure might not immediately make sense. I know that it's for when DMSO is involved in the treatments, but I don't think it jumps out at people who aren't used to drug preparations. This is a good question for basic experimental design: looking for, and controlling for confounding variables.


text:
What's the difference between prions and prion-like proteins?
If I added a prion domain to a protein, does that make the protein a prion-like protein or would it be considered a prion at that point?
I'm trying to understand what prions are, how they aggregate and what macroscopic shapes they conform to (i.e. a ring vs smaller micelles).
Thank you very much!

My understanding is that the principal quality of a prion is that it behaves like a prion in cells- the logic is a little circular.
A few of these criteria for acting like a prion (in yeast, where prions are most common):

Reproduces itself by "templating" (refolding of non-prion versions of itself into prion versions)
Sensitive to protein denaturing agents (which get rid of the prion protein conformation).
Dependence on protein chaperones which reproduce prions by releasing prion oligomers from larger prion aggregates. These oligomers go on to "seed" new prion aggregates.
Forms insoluble protein aggregates consisting of many copies of the prion protein.

An important subtlety here is that proteins with identical amino acid sequence can be both prion and non-prion in the same cell. It is a biochemical consequence of a specific protein structure, rather than simply a feature of the protein sequence. Thus, a prion domain confers the ability to become a prion, not necessarily "prion-ness" itself. This Scientific American article might be helpful regarding this point.
As an example of how these criteria are applied, this paper uses some biochemical and genetic methods to screen for the presence of new prions in wild yeast.
As a review of how prions oligomerize and form their classic aggregates, this paper might be helpful.
It is certainly true that creating fusion proteins with candidate prion domains is a common way of confirming that those domains are competent to become prions (see e.g. this paper). But there is usually a higher standard of evidence to show that some protein actually is a prion- usually by demonstrating the existence of heritable protein aggregates mentioned in point (4).
Hope that helps.


text:
Why sun rays don't burn our skin?
Can you explain (or direct me to a link) the process by which a photon of $8.10^{14}$ Hz is absorbed by the skin without damage, whilst a slightly more energetic one (UVB) makes damage?
What area of skin is necessary to absorb one single photon? How many photons of visibile light per $\mathrm{cm^2}$ are required in order to produce burns to the skin?

I actually don't understand the question about the skin area, (but that might be just by my lack of physics background), could you explain that a bit further?

You've put too many questions in there. Please narrow it down to, preferably, single question

Sun rays burn more at noon and in summer, because the angle of incidence of the photons determines the quantity of photons per cm^2. That implies that the skin can absorb a limited amount of photons. If we concentrate sun rays with a lens we can get hundreds of Celsius degrees (550°, or even thousands. I'd like to know how many photons per square cm are tolerated. The questions are all related

Proteins and DNA absorb light in the UV spectrum (both UVA and UVB) because that is the energy level at which pi electrons in the aromatic rings get excited (nucleotides and aromatic amino acids have that), so exposure to UV will cause direct damage to our biomolecules causing an inflammatory response and even cell death. Also, different chemical modifications may occur at the DNA level upon UV irradiation that may result in mutations that accumulating over time can lead to cancer.
However, due to the different wavelength, UVB releases most of their energy on the superficial layers of the skin causing more damage at that level.

What area of skin is necessary to absorb one single photon? How many
  photons of visible light per cm2cm2 are required in order to produce
  burns to the skin?

It depends on the skin color! Melanin is the skin pigment responsible for the variation of color in the human skin and it acts as protectant by absorbing and thus shielding UV light (it also has aromatic rings). The more Melanin, the darker is the skin, the more resistant is to sunburn.

Linked pictures!

and what about the pi electrons part! That's the core of it.

@canadianer: Alright, that is fair enough ... I might have underestimated that part of the question slightly. The last edit also made this more clear to me. Thanks! Removed the -1 and deleted my comments.

The reason that UV light causes sunburn, while normal light does not, is not founded in the energy carried by single photon. As stated on wikipedia:

Importantly, both sunburn and the increase in melanin production are triggered by direct DNA damage. When the skin cells' DNA is overly damaged by UV radiation, type I cell-death is triggered and the skin is replaced

The UV light can cause reactions in the DNA of the skin cells that directly damages the DNA. A low amount of this damage can usually be repaired by the cells, but a lot of DNA damage will lead the cells to die and cause inflammation reactions in the skin (the sum of which is then what we experience as sunburn).
[Here is a citation also explaining this, the paper is behind a paywall though].

What area of skin is necessary to absorb one single photon? How many photons of visibile light per cm2 are required in order to produce burns to the skin?

A single UV photon has no measurable size and can therefore in principle be absorbed by any arbitrarily small patch of skin. In practice only those photons that interact with the DNA in your skin cells are relevant for sunburn (that will be a very small fraction of all UV photons). Additionally the melanin in your skin will also absorb photons and therefore protect the DNA from the UV radiation, which is why people with darker skin get sunburn less easily. This also means that the amount of radiation/skin area required to cause sunburn varies from person to person and can be influenced by the ability of your skin cells to repair the induced DNA damage.

Technically- it does cause damage. The difference in wavelengths is utlimately the difference in potential energy that could be conveyed as damage; it just happens to be that the amount of damage visible light can do it less concerning than say ionizing radiation. Visible light, though weak by comparison, has been shown to accelerate the formation of free radicals (which spontaneously form on top layers of skin).


text:
Pregnancy from two parents with incompatible blood types, can it lead to complications?
Let's take Alice and Bob, both healthy adult human specimens. Alice is (A-). Bob is (B+).
If they decide to have a child, would Alice's pregnancy involve any additional risk or complications compared with, say, Abraham and Abigail's pregnancy (both AB+)?
Background
I overheard claims that pregnancies from parents with different blood groups can lead to complications in pregnancy due to interactions between the mother and the child's blood. (These claims were not officially backed, otherwise I would have brought them up on Skeptics.SE). The explanations and my Google browsing went beyond my biology knowledge. I know these pregnancies must be viable, since the AB group exists, but I do not know if there are edge cases that lead to complications that would not happen with same blood type parents.
Related question
Can the mating of a couple with Rhesus positive and negative blood types result in miscarriage? This question only asks about Rh+ and only if it leads to miscarriage.

Thanks, @AlexDeLarge. I overheard claims that pregnancies from mixed parents can lead to complications in pregnancy due to interactions between the mother and the childs blood. (This claims were not oficially backed, or I would have taken it to Skeptics.SE) The explanations and my Google browsing went beyond my biology knowledge. I know these pregnancies must be viable, since the AB group exists, but I don't know if there can really be some significant (>0.1% maybe?) edge cases that lead to complications that wouldn't happen with same blood type parents.

The rhesus factor (the + / - part of the blood group) can cause complications with pregnancy under certain conditions and lead to the so called Rh disease:
If the mother is rhesus negative and the father, rhesus positive; then the birth of a child with Rh+ blood group (inherited from the father) can cause the mother to build antibodies against this blood group. Therefore, a second pregnancy with a child that also has Rh+ blood group can have complications if no precautions are taken at any other point.
If these specific conditions are not all met, then no complications should arise from the blood groups.

The only complications that will occur will be in the birth of the second child, and that too if the second child is conceived soon after the birth of the first.
Let me explain.
Rh factor is an antigenic protein found on the surface of the RBCs of some individuals( rather, 'most individuals').

If the factor is present, the blood group is written with a positive(+) sign, and if it is absent, the negative sign(-) is used with the blood group. Therefore, in your example, Bob, Abraham and Abigail have the said factor on their RBCs whereas Alice does not.
As a matter of fact, our body has a mechanism because of which it produces antibodies against foreign antigens. Antibodies are simply substances released by our specialized cells to counter toxins and foreign antigens. These antibodies bind with the specific antigens (against which they are released) to render them harmless.

The fact is that these antibodies, once produced in our bodies, remain in the bloodstream for a certain interval of time, and there presence protects us from future infections by those antigens(This is the principle exploited in vaccination).
Let us relate this knowledge of antibodies and antigens to the Rh factor. Let's say that we make a blood transfusion from an Rh positive person(like Bob) to an Rh negative person( like Alice). Since for Alice, the Rh antigen is a foreign antigen(because it is naturally absent from her blood), she will get sensitized and develop antibodies against it. However, these antibodies will not attack the antigens immediately. They will come into action only if the antigens are again brought into the bloodstream, i.e. another transfusion is made sometime later. These antibodies will then  bind to the RBCs carrying it, and result in agglutination, or clumping of RBCs. The clump of RBCs thus formed blocks the passage of blood to the heart, resulting in death.

So, if Alice and Bob conceive a child together for the first time, the fetus will be Rh positive(because if the factor is present in any one parent, it will also be found in the child), and it will sensitize the blood of the mother. At this point, if you know some basics of biology, you will think that since the blood of the mother and the fetus never comes in contact, the fetal blood should not be able to sensitize the mother's blood. If you think so, you are absolutely right! The placenta does not allow their blood to mix. However during the parturition, rupturing of placenta often occurs, causing just a small amount of the fetal blood to mix with that of the mother. Even this small amount is enough for the mother to be sensitized and develop antibodies against Rh factor.
Now, if the second child(who will also,obviously, be Rh positive) is conceived soon, there will be a problem. The placenta is permeable to antibodies, and as a result, the anibodies developed earlier will enter the fetus and cause agglutination in the fetal blood, leading to excessive anaemia or even death. This is called erythroblastosis fetalis, or hemolytic disease of the newborn(HDN)
Thus, you can see that Alice and Bob will have a problem with their 2nd child, whereas Abigail and Abraham will not, since they are both Rh positive and Abigail won't be sensitized.
FACT The Rh factor was first found, and named after, the common Rhesus monkey!!


text:
Is there a non-bacterial source of lipopolysacchrides
I am wondering if there are any other non-bacterial sources of LPS. To my understanding, lipopolysacchrides (LPS) are components of the outer leaflet of gram-negative bacteria, but are there any other sources of LPS such as fungi?.

Yes, there is.
Lipopolysacchrides have been found in eukaryotes. The most famous example is green algae from Genus Chlorella.
According to Armstrong et al., (2002):

The lipopolysaccharides (LPS) are ubiquitous components of the outer leaflet of the outer membrane of all gram-negative bacteria and are the principal toxic products of these organisms (1). The membrane anchor of LPS is lipid A, a central phosphodisaccharide unit that is attached to multiple -hydroxy fatty acid chains. LPS also contains the novel sugar, 3-deoxy-D-mannooctulosonic acid (KDO). Although generally believed to be restricted to prokaryotes, specifically the gram-negative eubacteria and the cyanobacteria (2), an LPS-like molecule has recently been reported from a eukaryote, the green alga Chlorella sp., strain NC64A. (emphases mine)

Also, for further discussion on LPS in eukaryotes, please see Histochemical Evidence for Lipopolysaccharide (Endotoxin) in Eukaryotes.
Source:

Armstrong, P., Armstrong, M., Pardy, R., Child, A. and Wainwright, N. (2002). Immunohistochemical Demonstration of a Lipopolysaccharide in the Cell Wall of a Eukaryote, the Green Alga, Chlorella. The Biological Bulletin, 203(2), pp.203-204.


text:
Does the vagus nerve supply the human thoracic diaphragm?
The vagus nerve (CN X) passes through the oesophageal hiatus of the diaphragm at the vertebral level T10.
But does the vagus nerve actually offer any nerve supply to the diaphragm?

No, it doesn't supply thoracoabdominal diaphragm.

Sensory and Motor Innervation of the Crural Diaphragm by the Vagus Nerves https://www.sciencedirect.com/science/article/pii/S001650850901511X?via%3Dihub


text:
Whose horns are these?

Can anyone please help me identify these horns?
I guess they belonged to either European or Asian species. I don't know anything about their history -- they are my grandparents' who are from Moscow, Russia. The horns are at least 20 years old, I guess even more.
The length from the tip of each horn to its base (straight line) is about 35 cm = 13.7 inches.
A friend of mine suggested those might be a cow's horns, but I'm not sure.
Maybe someone can recommend a resource where it's possible to find it out?
Thanks in advance!

Hello Elizaveta, there are a couple of facts needed to ID a specimen related to living organism; like size and background of the specimen (in this case history of this wall mount).

Hello and thank you for your suggestion! I will update my post.

A single picture of aged and polished horns is not going to be that easy to give a confidently correct answer, but I can at least say that they appear to me to be horns of a yak or cattle steer.
See for example, the horns of a female domesticated yak (Bos grunniens):

the horns sweep out from the sides of the head, and then curve forward; they typically range from 48 to 99 cm (19 to 39 in) in length. The horns of females are smaller, only 27 to 64 cm (11 to 25 in) in length, and have a more upright shape.

Wild Yak (Bos mutus) have similar, though smaller and sometimes curvier horns:

The Wild Yak’s horns are grey to black and curve outwards, forwards, back, and slightly inward. The horns of males are larger than those of females. The horns of male Wild yaks average 42.6 centimetres (16.8 inches) in length, from tip-to-tip, and 35.2 centimetres (13.9 inches) in circumference. The horns of females average 32.2 centimetres (12.7 inches) from tip-to-tip and 19.5 centimetres (7.68 inches) in circumference. [Source].

 Yak (Bos mutus) in the Lüneburg Heath wildlife park, Germany. [Source].
Both Yak species are present in Asia:

Though there are over 12 million domestic yaks in the Central Asian highlands, fewer than 10,000 Wild yaks survive.

However, as I said, these could just as likely be the horns of any of a number of variety of steer cattle. (There are over 800 varieties!).
See for example, this Corriente cow in California:

If you Google "steer horns" you get dozens of shapes and varieties of mounted horns. You could comb through looking for similar specimens...

If I had to guess, since your grandparents are from Russia where yak are present, it seems to me it would be more interesting/impressive to mount yak horns vs just steer cattle horns. But that's just a personal guess.
Here's a picture showing a variety of species and their horns:

Not sure of the source of the last picture, but if you figure it out, you might gain access to another 25 horn types! :p

Thank you so much for your answer!! I appreciate your help!

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


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Why is it that I can understand speech through one ear better than the other ear?
First, I do a lot of music so I'm used to pick up details in sound and I have had hearing tests showing that my ears are quite well balanced, for my age, without any dead spots.
When I am in a social situation, I will hear people's voices equally well on both sides, however I will 'understand' dialog better on one side.
I remember reading many years ago that this is normal and there is a known reason for it, but I can't really find much about that topic.
Does anyone here know why this is happening?

I remember reading many years ago that this is normal...

Indeed, this is normal and quite expected: understanding one's voice is a brain task, not an ear (sensory organ) task, and if there is difference in the parsing capabilities between the left and the right hemisphere (which is the case, as we are going to see soon), the stimuli captured by the right ear will be treated differently from the stimuli captured by the left ear.
To understand what's happening here we have to know two things: the Wernicke's Area and Dichotic listening test.
The Wernicke Area, quoting Wikipedia, is...

...located in the posterior section of the superior temporal gyrus (STG) in the (most commonly) left cerebral hemisphere. It is involved in the comprehension or understanding of written and spoken language (in contrast to Broca's area that is involved in the production of language).

Thus, in most people, the left hemisphere is responsible for (most of) linguistic capabilities, both producing language (Broca's area) and understanding language (Werneck's area).
Now comes the dichotic listening test. In the dichotic listening test, two different stimuli are presented to each ear. The results of the test indicate that there is preference for the information captured by one of the ears.
According to Freberg (2010):

Dichotic Listening Is Related to Hemisphere Lateralization for Language: When conflicting information is provided to the two ears, the person who has language lateralized to the left hemisphere will show a preference for the word heard by the right ear. The information presented to the right ear will reach Wernicke's area in the left hemisphere faster than the information presented to the left ear. (emphasis mine)

Here is an image explaining the test (click for a larger size):

As you can see, there is a advantage to the right ear. According to Hugdahl et al. (2003):

In the present paper we report on speech perception in left (n=16) and right (n=10) frontal lobe nonaphasic patients compared with healthy controls (n=26). [...] The results showed significant differences between the left and right lesioned patients in their performance on the dichotic listening test. While the right lesioned patients and the control subjects had a normal and expected right ear advantage, the left lesioned patients performed almost at random with regard to the right and left ear stimulus. (emphasis mine)

Sources:

Freberg, L. (2010). Discovering biological psychology. 1st ed.
Hugdahl, K., Bodner, T., Weiss, E. and Benke, T. (2003). Dichotic listening performance and frontal lobe function. Cognitive Brain Research, 16(1), pp.58-65.


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What characteristics of the protein folding process ensure that the energy landscape is a funnel?
The folding funnel hypothesis states that the energy landscape that proteins observe when they fold is funnel shaped with a single global optima. This ensures that no matter what sequence of folds the protein follows, it should eventually end up in the same folded configuration thanks to the laws of thermodynamics.
For example, see this illustration of the energy landscape from Dill & MacCallum (2012) "The Protein-Folding Problem, 50 Years On" Science 338 (6110) pp 1042-1046:

Clearly, the folding works because the energy landscape is funnel shaped. Any other configuration, e.g. a landscape with multiple significant local optima or a flat landscape, would result in a protein folding in all kinds of different ways.
What are the characteristics of the overall system that ensure that the energy landscape is funnel shaped, and that nearly any protein in an unfolded state will reach the global optima? (e.g.: is it because the proteins themselves have certain statistical properties? or it is something to do with how the types of "moves" the protein makes on the energy landscape?)

I'm not sure I follow your question entirely. Protein folding is dictated by both entropy and enthalpy. You may be interested in this: https://en.m.wikipedia.org/wiki/Anfinsen%27s_dogma

Thanks for the link. I guess the question can be rephrased as why is the energy minimum unique and so "easy" to find due to the funnel shape of the energy landscape? Did this property evolve somehow via selection (so there might be folding molecules with multiple energy minimums) or is it inherent in nature?

For any combination of amino acids there is going to be a conformation which is at the lowest energy and, when plotted, this would have to look like a funnel. It is plausible, though perhaps unlikely, that there could be more than one low energy conformation that is stable (the prion protein may be an example). However, since protein function depends on structure, it is likely that evolution would prevent multiple protein conformations that are accessible and stable.

Huh. Isn’t this a seriously outdated hypothesis? The energy landscape of protein folding does have significant local minima, and correct folding often requires specific codon sequences and cofactors. So I think the premise of this question is fundamentally not true.

good point, maybe it is an outdated hypothesis.

I can't help but think of prions, & the potential catastrophic & fatal consequences of 1 alternative folding of just 1 protein - having alternative funnel outputs to the desired one can be seriously problematic, & even 'infectious'..

Naturally occurring proteins are evolved such that this is the case
Natural proteins only occupy a very small amount of sequence space. For a 200 aa protein, there are $20^{200} \approx 10^{260}$ possible sequences. There are nowhere near that many naturally occurring protein sequences, even if you take into account all the different alleles in the different organisms in the world.
What happens when you synthesize and express a random (non-natural) protein sequence? You get junk. It doesn't fold or it aggregates or something else happens. You don't get a stably folded protein. Heck, you don't even need to have a fully unnatural protein. You can take a naturally occurring protein and make a few mutations in it, and end up with non-folded junk.
Evolution has a very strong selective pressure to make sure proteins can fold properly and beat Levinthal's paradox. If a protein can't fold, it can't perform any function in the cell, and thus there's no selective pressure to maintain expression. (The promoters get trashed, and the DNA gets mutated away to "junk" DNA.) Only if the protein is stably folded is selective pressure maintained. So you get the one-in-a-million sequences which does have a decent folding funnel.
So it's not that there isn't protein sequences out there with a flat energy landscape, or an energy landscape with lots of local minima. It's just that whenever such a protein forms, it can't fold. And if it can't fold, it's freed from evolutionary pressure and disappears from the gene pool - either because the organism that holds it can't survive without it, or because random mutations wipe it out with random noise. It's survivorship bias -- you see proteins with a reasonably well-formed folding funnel because they're the only ones you would see.
(There are proteins out there with less-than-robust folding funnels, or with alternative energy states. A brief search of the literature will turn up a number of examples where protein folding requires cofactors or chaperones. Or where a protein has two different folded states, depending on environmental condition. Or where the most commonly folded state is only a meta-stable state, and there's a more stable conformation which the protein will convert to, if given a chanvce - amyloid fibrils being the most common example. These are refinements on the general principle. You don't need a rock solid folding funnel, you just need one "good enough" for the organisms' purpose.)

You can see some of this in the "de novo" protein designs that come out of labs like David Baker's. They're able to take a protein topology and use a computer to design a sequence "from scratch" which folds to that topology. But far from all of the sequences which their computer program spits out actually will fold. Only a small fraction of such designs will actually fold into a compact protein.
But one of the things that they've found which improves their success rate is to check the designs by "forward folding". That is, the computer spits out a design which it predicts will be a low-energy sequence for that structure. But just having a sequence which is predicted to be "low energy" isn't enough. As an additional step they run the sequence through a folding simulation to see if the sequence they designed also has a clear preference for the designed state. Roughly speaking, checking if there is a clear "folding funnel" which will drive the protein toward the desired folded state. By doing this subsequent computational check, they're able to greatly increase their success rate when the proteins are actually expressed.


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Do seeds use cellular respiration when they are germinating?
Do seeds use cellular respiration when they are germinating?

What have you found while searching on the internet on your own? PS: Consider asking yourself why seeds have a high fat content.

Seeds have preserved energy and nutrients in the form of cotyledons that are used for germination because they can't harvest their own energy until they grow leaves for photosynthesis. But I don't know whether they use cellular respiration, I'm guessing they do?

Google: germination oxygen consumption

@Timothy yeah, and how do you think the stored energy is utilised? How is it converted from its physical form of fats/carbs to help its growth?

Those stored fats and sugars have to be burned to be utilized. Besides how ridiculous it would be to have a multicellular organism mature using only fermentation.

So seeds use their stored nutrients via cellular respiration? Thank you!

It would be helpful to provide citations to back your statement.


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What is the difference between contig- and read-based sequence alignment?
I am trying to understand the difference between read based and contig based alignment. Is contig based alignment refer to de novo assembly and then it is align to a reference genome. I am confused that if you have read based alignment then what is the importance of aligning contigs on the reference.

I have never heard the term “contig based alignment”, and your question is the only Google hit of this exact query (apart from a 2012 patent application).
That said, and without knowing the exact context, I am assuming that you are essentially right: contig-based alignment probably refers to the de novo assembly of reads into contigs, which are then aligned into a scaffold by use of a reference.


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Identify insect

I am from north east India and I found a really beautiful bug in my backyard.
Can someone please help me identifying it?
Size: about 3 cm long and 1.5 cm wide.

I can't say what species this beetle is but I think it's a species in the Anomala genus in the subfamily Rutelinae (Shining Leaf Chafers). One photo I can link you to is found at Coleoptera Atlas Anomala grandis.
Dorsal view of Anomala grandis

Ventral view of Anomala grandis

The only reason I wouldn't consider it specifically to be the beetle you found is because the beetle in the photo occurs in Thailand. How far it range is, I have no idea. It might be found as far as you are. A common name for it is little green leaf beetle. Coleoptera Atlas lists its maximum size at 27 mm. There is another larger Anomala species that looks similar called Anomala cupripes or large green chafer beetle. I wonder about the reliability of some of the sources though as it's only supposed to be 20 mm! The name is also one used around 1900 so it might even be the same as A. grandis.
If the photos look like they fit your beetle, and depending on the size of yours, you can use this information to make some inquiries in your region. It's all I can do as resources in English about insects in other parts of the world are often limited.

I think the hair is missing from the photo

It looks like a Chrysina Lecontei, a type of scarab. Perhaps you can provide a better top and bottom photo (directly above and below)?

Sorry but it was dead when i found it,and i dont get the chance to take more photos.

This is a scarab, but the species given in the answer is from the wrong side of the planet (see http://bugguide.net/node/view/134203/bgimage for images with locality data); Google-searching "Scarabaeidae India" results in more than 100,000 hits; fortunately a starting point (the Fauna of British India  series) does have a partial online presence (see here: http://www.biodiversitylibrary.org/item/36758#page/5/mode/1up) but is also quite old: the first part of the three available dates from 1910 ...

Please remember that the Latin name of the species starts with lower case (C. lecontei).


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Reward pathway sequence of events
So I've been reading a lot of papers on the reward pathway. But since I'm not schooled in any relevant knowledge I'm having trouble grasping the chain of events. Most papers detail just bits and pieces, but not the full sequence of events.
I'm trying to grasp how the error prediction signal works.
This is my guess so far:
Players:

Photosensitice cell A
  Light processing neuron B
  Dopamine neuron C
  Motorneuron D

Event:

Light strikes A
A triggers B
B spikes after N triggers.
B triggers C
C spikes after N triggers.
C keeps repeadetly spiking for as long as its internally coded reward size/duration expectation.
D receives predecition triggers spikes causing action.
  Reward comes, neural connections are strengthened.
  If reward doesnt come in predicted time connection degrades.

Am I correct in this deduction or way off?
How does the actual reward get communicated? By dopamine release in blood?
By the same neurons that coded the reward prediction? If so, how do those exact neurons get triggered to release reward?

just within the visual processing you will have many neurons processing the information before it goes on to other areas. after all, you are not afraid of a black dot at a certain location of your retina, but of the spider (or whatever). Your 'neuron B' is not a single neuron, but a whole brain area. However I don't know how far up in the processing cascade a signal goes before the information spreads to other brain areas. It might also differ between signals depending on their abstractness. e.g. I expect that being afraid of speaking in public will involve more/different processing.

i understand that, i tried to simplify the process to understand what happens within the reward pathway. Error prediction signal, reward.  How those two are communicated by an event source, and unrelated reward trigger. I see food, i get appetite. Food is in mouth, im happy. How does the food in mouth, hot relaxing bath, sunlight on face get translated to a reward signal to the neurons that were triggered by the prediction signal

I think it's too much to explain the whole reward circuitry here. You would be best off searching for review articles about reward pathways. For example, searching something like this on pubmed: https://www.ncbi.nlm.nih.gov/pubmed/?term=reward+prediction+signal+review There are several results that answer your question but do note that this is still an area of active research, it is possible to present hypotheses but the full circuitry is not perfectly known, because there are multiple contributing pathways.

@BryanKrause I realize it's a lot to explain in one answer, but it's really hard to find one article that summarizes the path from a to be in a "flowchart" type of style. They usually just focus one one piece, making it really hard to figure out how it all fits together as one coherent piece. Ideally i'd have a simple flowchart that would explain in very rough gist how the current theories are how a trigger ends up in a response and how an error correction signal works in it all.

Essentially that's what I remember, but there can be a lot more steps between A and C, i.e. more pathways interacting in different systems to produce an associative memory. Pavlov's dogs is the classic example:
1: Pavlov rings bell, dogs hear bell
2: Pavlov feeds dogs, (dogs rewarded)
3: Repeat 1 and 2 for a few days.
4: Ring bell, dogs will salivate and expect food, even if no food is on the way.
So, in the skull, the dogs are making a link between hearing a bell and a reward.
Dopamine is released at dopaminergic synapses, the limbic system is probably the best understood part of the memory/reward system, particularly the mesolimbic pathway for reward.
Neurons get triggered by presynaptic neurotransmitters, some require convergence of signals to reach threshold and trigger an action potential. Connections are strengthened by long-term potentiation, which has been argued to be the basis for memories, but that's a massive topic I'm not qualified to discuss.
I haven't heard of the "error prediction signal" before, might be a new discovery/thinking that I'm a bit behind on.

Yes indeed error prediction signals have been discussed for decades now, it is not a new concept. I appreciate the attempt at an answer but there is really very little here that actually answers the question, instead you are explaining a behavioral paradigm. Everything you say is correct, though. I think the original question is just not answerable in a SE format, it is much too broad and the circuitry is not fully understood yet.

It is a bit of tangent but one current idea is that humor itself exists as an error correcting mechanism. a way of dealing with pathways that make bad predictions


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Connectivity of the Superior Colliculus
Does anyone know anything about the connectivity of the superior colliculus? Or know of any straightforward published literature?
I've got that the superficial layers receive input from the visual system and the deep layers have multi-sensory inputs, but I'm finding conflicting information about the specifics.
I've read one source that suggests inputs are from magno and konio cellular retinal ganglion cells. But as I understand it, these are cell types in the lateral geniculate nucleus, so it's not clear if the inputs are from the LGN, or the retina.
Edit: Figure 2  here, shows "koniocellular" ganglion cells. Which I can't tell if they're meant to come from the LGN, or retina.
This article discusses some of the connectivity, but only with regards to eye fixation, rather than a general overview.

Please cite the sources.

Edited to add a couple of the sources.

(About the tectospinal tract) the tectospinales fibers originate in the superior colliculus, its axons pass ventromedially by the central gray matter and cross in the posterior tegmental decussation. The upper colliculus receives visual information, and the tectospinal tract is believed to act as a mediator of reflex eye movements in response to visual stimuli (Neuroanatomy of Crossman and Neary pg 81).
A relatively small number of fibers leave the optic tract, before reaching the dorsal nucleus of the lateral geniculate body, to terminate in the pretectal area and superior colliculus (fibers involved in pupillary reflex mediation) (Neuroanatomy of Crossman and Neary pg 157).


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Would a stray ant re-home into a foreign colony (of the same kind) and will the colony accept an alien ant?
Let's say an ant got into my pocket as I was sitting in the park today. At home, I shook off my coat and the ant fell out and scurried out to my garden, which has ant colonies of the same kind.
Would the ant try to assimilate into that colony and would the colony accept it?
How would each know about the other's non-relation?
Thanks

Ant behavior is controlled by pheromones. They do not "know" things but an ant from a different would be recognized as a source of energy and probably killed and eaten.

With fairly high confidence, the ant would probaly be accepted. While normally ants live in colonies, you can move ants between colonies as long as they are part of the same supercolony. https://en.m.wikipedia.org/wiki/Ant_colony

If they are from a different species, they won't accept each other.
If they are from the same species, it depends of the species:

Some species won't accept any other ant born in a different colony, such as Lasius Niger
Some species form a supercolony which can gather ants from the same species over hundreds or thousands of kilometers, such as the Argentine ant on the coast from Spain to Italy.

To know more about ants, I advice this excellent book: Wilson et Hölldobler, The Ants, Belknap Press, 1990, (ISBN 9780674040755)


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How Ants can eat Chili peppers also?
I captured a picture where ants feeding on Chili peppers also, I was shocked.

Actually this peppers is one of the best way to get rid of ants is to prevent them from ever considering from home.

What exactly is your question?

@BryanKrause I edited my question, still is it unclear?

Yes it is still unclear you seem ask why the ants eat the pepper then state it repels them instead. Since I have never heard of chili peppers as an ant repellent, a source fr this claim might help. Are you asking why insects can eat chili peppers with no problem? The answer is capsaicin only works on mammals and possibly fungi.


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Dinosaurs vs. humans
If dinosaurs were here so much longer than humans, why did their natural selection not account for higher intelligence, as is the case in humans?

Perhaps this is already answered here: https://biology.stackexchange.com/questions/11254/why-were-dinosaurs-not-as-smart-as-we-are?rq=1

Some dinosaurs are extremely intelligent, being able to use tools and make tools. However, this is a duplicate question, VTC

Welcome to Biology.SE. Even if the question is short, it is sufficient to show a good number of common misconception about evolutionary processes. I'll be brief in commenting on them and will invite you to seek for more knowledge in an intro course and related posts.
Phrasing

their natural selection

Natural selection is a concept (the concept of fitness variance in the population correlated with an additive genetic variance). Natural selection is not a thing that is owned be a population. It is not "theirs"
Your misunderstandings
Evolutionary time
Any living species on earth has 3.5 billion years of evolutionary time. There is no exception to that as we all share a common ancestor. Humans are not less evolved than a crocodile or a bacteria. We all have the exact same evolutionary time.
Evolution of intelligence
Higher intelligence is NOT what natural selection will tend to. Having high intelligence is most often rather negatively correlated with fitness.
Related posts:

Why evolution should not be equated with progress?
Why were dinosaurs not as smart as we are?

Source of information
You would make good use of a very short and very introductory course to evolutionary biology. There is a large number of free ressources online. You might want for example to consider Understanding Evolution by UC Berkeley.


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Do mosquitoes allow for DNA transfer between unrelated species?
A mosquito can bite individuals of different species and eventually allow for some blood of one species to enter into the bloodstream of another species which I suppose may eventually cause DNA transfer, that is horizontal gene transfer
Do mosquitoes increase horizontal gene transfer among the species they parasitise? If yes, is it considerable or negligible?

The question is rather broad for the moment. Sure mosquitos carry diseases, they will clearly affect other species evolution (incl. the famous interplay between malaria resistance and sickle cell amenia). Is there any selection pressure or any co-evolutionary mechanism you are interested in?

@Remi.b, nothing in mind, just curious if the trace amounts of transfer is having an impact over the long term, and if so, was it large or negligible.  Simple curiousity, having effectively zero bio science expertise.

What do you call the trace amounts of transfer? Do you have in mind existence DNA transfer between individuals of the same species via blood transfer or something like that? Or are you wondering whether the cost of the blood loss via mosquito suction is important?

@Remi.b.  More dumbed down than that I guess.  Do we have 'bits of  antelope or elephant traits in us' because of mosquitoes.

Oooh ok, I think I get your question. I completely rephrased your post. If I misunderstood your point (or if you don't like the edit for any reason), feel free to roll back the edit.

@Remi.b.  Thanks.  Nice edit, although you probably made me sound smarter in this area than I'd confess to.  :-)

In general foreign materials may be transferred from one organism to another in a mosquito, as is obviously the case with malaria, but for DNA to make it from inside the cells of one organism to inside the cells of another organism is exceedingly rare. In general DNAses and RNAses are present anywhere around living cells so when DNA is released it is quickly chewed up into useless fragments. Most likely this happens readily inside the digestive tract of a mosqito (Evolutionarily this makes sense as it would be extremely bad if a mosquito started absorbing genes from any of the organisms it was feeding off of!). Furthermore, DNA is an enormous charged molecule and does not easily pass through a cellular membrane. In a laboratory setting, DNA may be transferred into organisms with the help of electroporation or "gene guns" but this requires large amounts of identical genes to be effectively forced into cells, and even then, efficiencies of gene transfer are low. In short, no, it would be effectively impossible for a gene to be transferred from one organism to another by a mosquito. However, if a virus gets transferred by the mosquito...

...not to mention that DNA would have to enter not just any cell but specifically cells in the germ line.

I would not use malaria as a general justification that foreign materials can be transferred by mosquitoes. Malarial sporozoites must actively migrate to the salivary glands of mosquitoes in order to be transmitted in their bite.