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What kind of Brazilian Arthropoda is this?
It looks like a Diplopoda, but I've never seen anything like that. A friend took those pictures in the Brazilian Cerrado (Goiás state, Brazil) these days (October, start of rainfall in Spring). It was inside a country house, she already found it dead.
She said it has about 3 cm (~1.2") long. We can see it's not so small as a Symphyla or Pauropoda. Looks like it has 12 pairs of legs.

I was fooled by the red marks in its back, that made me believe they were each pair of marks in a segment. Looks like they're distributed in one pair of red marks for each 2 segments. Maybe that's a mimic of some similar Diplopoda (which usually have such colored marks, see for instance Rudiloria)?
Looks like it's some species of Scutigera or some related group.


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Which fly is this?
This picture was taken in the Brazilian Amazon, upper Negro River, at daytime. The fly, about 1 cm long (maybe a little more) was flying next to us, as if to drink sweat. It finally landed on my friend's arm and I photographed it. Can anyone identify it, at least at family level?

EDIT - I've found a second pic. Left the index finger nail for size reference.

My hunch is that it's a hoverfly (family Syrphidae).

(DISCLAIMER: I'm no expert in flies and am more or less educated guessing.)

Here is an example picture of a somewhat-morphologically similar species (North American species, but whose genus is found in the neotropics):

 Toxomerus marginatus ; Credit: Ron Hemberger ; Source: Cornell University
Hoverflies are found all over the world and often demonstrate bright (often yellow) coloration. Usually, the yellow alternates with black, and there are in fact a number of bee mimics! Their sizes range quite drastically, too: 0.5-3cm [Source: Ohio State Extension].
The give-away that it's a fly (i.e., order Diptera) is the fact that it only has one pair of prominent wings. [Source: Ohio State Extension]
One of the tell-tale signs to differentiate Syrphidae from other flies is the presence of a seemingly extra vein in its wing. This is actually a false (or "spurious") vein that doesn't connect on both ends, and it parallels the 4th longitudinal vein. [Source: Britannica].

 Spurious vein (or "vena spuria"). Image source: Draw Wing

 Comstock-Needham_system. See "SV" for the spurious vein. Image Source: Wikimedia
The image in your photo does not show the wing very clearly, but I can at least convince myself something similar to the SV is somewhat visible in your specimen's left wing:

I've had many experiences of hoverflies lingering around people and following us along even as we walked through the forest for quite some distance. I think they may be attracted to bright clothing as they are very important flower pollinators.
I'm no expert in hoverflies, so my search ends here. However, if this is in fact a hoverfly, it turns out you can find online access to Thompson's (1999) "A key to the genera of the flower flies (Diptera: Syrphidae) of the Neotropical Region including descriptions of new genera and species and a glossary of taxonomic terms used" which may be of use to narrow down to a more specific taxa.
 Thompson, F.C., 1999. A key to the genera of the flower flies (Diptera: Syrphidae) of the Neotropical Region including descriptions of new genera and species and a glossary of taxonomic terms used. Contributions, Ent. International.

UPDATE:
I've actually grown fairly confident that I actually came to the correct genus in my example picture above. Toxomerus is found in North and South America, with known species in the neotropics. According to Wikipedia and inaturalist, this genus is distinguished by 1) relatively small size (6-9mm) -- check --, 2) unique abdomen markings -- check --, and 3) a posterior triangular indentation of their eye -- we can't see this in either picture.

 Eye indentation. Source: Instituto Nacional de Pesquisas da Amazônia
I'm still uncertain about species, but G.F.G. Miranda provides a list of 29 species found in the Brazilian Amazon (sourced from Macquart 1855). [Bourges & couri (2009) apparently revised these species, but I can't gain access to their publication].

 Toxomerus species found in Brazilian amazon. Source: Instituto Nacional de Pesquisas da Amazônia
Of these, non-reputable pictures of T. floralis and T. watsoni (e.g., here) seem most similar. However, due to the lack of reputability of the sources I could find (and lack of sources for most other species listed), I don't feel confident narrowing for you at this time.

 Borges, Z.M. and Couri, M.S., 2009. Revision of Toxomerus Macquart, 1855 (Diptera: Syrphidae) from Brazil with synonymic notes, identification key to the species and description of three new species. Zootaxa, 2179(1), pp.1-72.

Thank you! I've found a second pic, not sure if it helps any further.

https://www.inaturalist.org/posts/14985-identifying-toxomerus-hoverflies

source: Stack Exchange

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Why did ants and meliponine bees lose their sting? What's the evolutionary advantage in it?
We know Aculeata is the Hymenoptera’s lineage where the ovipositor evolved into a venomous sting. However, most ants have lost this sting, as well as meliponine and some other bees.
Kerr & Lello (1962) say that “there are at least thirteen ways in which stingless [meliponine] bees protect themselves, making stings obsolete”. Since this subject is being researched for more than 50 years, we hope that some advances have been made in the understanding of this specific evolutionary change.
What's the evolutionary advantage for these groups to lose this apparently awesome defense system?

Does https://biology.stackexchange.com/q/35532/27148 help answer your question?

@BryanKrause It does raise interesting hypothesis, but I'm hoping a specific study may exist on the subject I've brought. For instance, counting how many times the sting was lost within Aculeata, proposing specific hypothesis about why the sting wasn't any longer required in each clade, etc. Within meliponines, some species have painful bites, but others don't. How do the latter compensate for that apparent lack of defense abilities?

It's not typically possible to do anything but speculate and tell just-so stories in these cases, which is why we have that canonical answer.

@BryanKrause It's not always a matter of simply just-so stories. There may be specific structures, behaviors, hormones, etc, that have evolved in such groups that provide a more plausible explanation for them.

I voted to close for Hwk (how far did you get with your own research?) because the post Bryan mentions answers the question you are asking sufficiently. If there is something you have found that specifically contradicts or expands on that answer, I'd include it here.

@James I asked a question about evolution of Hymenoptera, not a general question about evolution. Kerr & Lello (1962) say (in the abstract) that "there are at least thirteen ways in which stingless bees protect themselves, making stings obsolete". However, Western science is not open to the public, and this site, which could be an option to that, is full of perfectionists like you trying to close perfectly valid questions. C'mon!

@Rodrigo Maybe this is an XY problem? You are asking about why ants and some bees have lost their stings, but if what you actually want to know is what alternatives these stingless insects have to protect themselves why not ask that question instead, citing Kerr & Lello?

@BryanKrause Even if we know about other defense mechanisms, it would still be interesting to know the evolutionary costs and benefits of each -- this could explain the change. So I think the way I asked is more direct.

Does this answer your question? Why do some bad traits evolve, and good ones don't?

@MattDMo That's the first comment here, for which the answer is No.

Many ants do have functional stingers. see the fire ant.

@John I know, the text of the question says "some ants". And fire ants don't have a sting, as far as I know, Ponerinae ants and some other subfamilies do.

@Rodrigo fire ants do have a venomous string, https://thekidshouldseethis.com/post/sting-prey-raft-the-successful-behaviors-of-red-imported-fire-ants

@John Indeed, sorry. I thought that, like most Myrmicinae, they didn't.

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Will breathing through mouth result in any disorders?
My nose is slightly bent. When I was born, I had an issue with breathing. My mom said that doctors had inserted a breathing tube in one of my nostrils. This tube may have caused the deformation. From childhood, I breathe through my mouth. Will there be an any problems in the future? Do I have to take any treatment? Please suggest.

can you make the question little more general, it might be flagged for personal medication.

I don't think this can be generalised. To generalise, he'd need to understand his problem deeply, which he does not. @roarer should consult his doctor as soon as he can - I'm sure it's not a good idea to breath with your mouth. You'll get infections, which are normally filtered in nose.

@TomášZato I totally agree with that.

Yes, you become more prone to infections. Would be ideal to consult a doctor so as to get your nose sorted out. I wonder why they didn't try to fix it when you were a child as that would have been much easier than now.

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Division of Polar Body
The first polar body formed after meiosis-I is completed in oocyte, may or may not divide.
Why is the statement that "it may or may not divide"? Is it random ?

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Satisfication with irrelevant things
I am not sure if this question is better suited CogSci.SE so please tell me.
My question is why are we satisfied when we get things that aren't useful in any important way? For example, relating to Stack exchange, why are we satisfied and happy when we get badges because badges don't increase reputation or help you get privileges in Stack Exchange. Similar with Winter Bash. Why are we happy when we get hats? They are just for decorations. Is there a biological explanation for this?
What chemical leads to us getting that feeling of satisfaction?

In the grand scheme of things, stack exchange reputation seems about as irrelevant as stack exchange badges…

@canadianer well not for me bcos for some of these questions, the topics are based of projects I am doing so I need reputation to do more with my question so I can get answers so I can finish my projects...

If the question is re-stated as "what is the neurotransmitter mediating the sense of reward" this question is acceptable (DA, as answered). As the question stands now it reads "what is the neurotransmitter mediating the sense of irrelevant rewards?". That doesn't make sense to me, as relevant and irrelevant rewards are highly subjective and opinion based.

Dopamine is one of many neurotransmitters which modulate information passage between one brain area to another. Dopamine is thought to play important role in  pleasure, addiction,
and learning.Massive increase in the
amount of dopamine released in the brain during video game play, the releasing of dopamine
are in areas thought to control reward and learning.

Reference

Certain neural structures, called the reward system, are critically involved in mediating the effects of reinforcement. A reward is an appetitive stimulus given to a human or some other animal to alter its behavior. Rewards typically serve as reinforcers. A reinforcer is something that, when presented after a behavior, causes the probability of that behavior's occurrence to increase. Note that, just because something is labelled as a reward, it does not necessarily imply that it is a reinforcer. A reward can be defined as reinforcer only if its delivery increases the probability of a behavior.

The reason why we are happy when we get these decorative items is because they are things which we can possess. Reward system is responsible for this kind of behavior, when we gain or achieve something in life its usually gets rewarded in the form of a pleasure. Foraging ants and bees are provided with these reward systems and which in turn makes these animals to derive a pleasure out of their daily achievements. Whether in life, video game or stack exchange or anything, an achievement is something brain thinks relevant and rewards it with a pleasure in mind.
Considering badges in stack exchange, really badges are an analogy to reputation. When we have more badges usually our charisma increases like in the case of reputation. Also levels and scores in games,achievements in office, stack exchange badges and hats all fall under the same analogy. So when we have more badges we are meant to be more successful and brain will reward us to attain more badges and also people like hats too.

References
Digital Media: Transformations in Human Communication - Paul Messaris, Lee Humphreys
Cyber Junkie: Escape the Gaming and Internet Trap - Kevin Roberts


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Why doesn't water enter my body through my anus or genitals when swimming?
So when we swim, we can make water not enter through our nose and mouth, simply by holding our breath. However, the mouth and the nose aren't the only cavities. What about the anus and the genitals? They obviously can't "hold breath", so how do they stop water from entering?
I thought the reason is gravity, but then, people would be killed when diving because your butt is facing up, against the gravity.
Another explanation might be that the internal pressure is higher than the external one, but I fail to recall any organ that creates the pressure..

It is worth noting that some small amount of water can get in through these openings as there are a few parasites that rely on this as their transmission vector.

"We can make water not enter through our nose . . ." this is not as simple as you make it sound. I rely on a noseclip. Conversely, the other orifices you mention at least have a sphincter.

For the same reason that when you urinate or use the toilet, you have to exert pressure and urine or faeces just does not simply leak out when you stand up. The urethra seals shut when the urethral sphincter muscles relax. Similarly Sphincter ani externus muscle seals shut in the anal canal when there is no antagonistic force. So water can't just simply enter our body in such huge quantities that we die. It is possible to get more water through your anus with some pressure which is what happens when you get an enema.


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How much DNA of Albert Einstein is recoverable?
Since there seem to be five biological descendants of Albert Einstein, and the original chromosomes of him distributed among them ...
Is it possible to recover enough DNA of an individual from his progeny and proceed to clone him? Any information would be helpful

Technically I think not even if his own children were alive but I am very interested in an answer.

A large chunk of Einstein still exists (pickled brain) and protocols exist to recover DNA from formalin fixed tissues.  It wouldn't be easy, but in theory, you could derive its full sequence and synthesize artificial chromosomes for cloning.

During the generation of gametes (sperm, eggs), chromosomes can cross-over - this swaps paternal and maternally-derived genetic material.  So none of the descendant's chromosomes would be a direct copy of Einstein's, and furthermore, each offspring receives half of its genetic complement from each parent.  This means that if you pool the DNA data from small number of offspring you may not obtain all the elements of one parent's DNA or be able to assign that data back to a specific 'original' chromosome. (On top of this you would have to determine which sequences in the offspring came from the other parent).
If I was cloning Einstein, I'd use his DNA.  Is his comb in a museum ? A tooth? A letter he licked?  A large chunk of Einstein still exists (formalin fixed brain) and lab protocols can recover DNA from formalin fixed tissues. It wouldn't be easy, but in theory, you could: i) derive its full sequence and ii) synthesize artificial chromosomes with suitable epigenetic modifications, and iii) inject those into enucleated eggs for human cloning or iv) transfect them into enucleated cells from a cell line, make iPSCs and then fuse those with ~8-cell fertilized embryos.
(Spoiler - not technically do-able today and almost certainly illegal in most states/countries).
For a related movie treatment, the Boys from Brazil  tells a good story - warning Nazi content.

thanks a lot for your attention to my question , and the illegality of this work is amazing !

i) and ii) will probably never be impossible due to genomic regions that cannot be sequenced, un-resolvable epigenetic statuses and the major difficulties in synthesising ekaryotic chromosomes. Nice thought experiment, though.


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How the conjunctivitis virus spread just by seeing a person's eye who is infected

Conjunctivitis or 'pink eye'.
I have a few questions on conjunctivitis. When I was suffering from conjunctivitis, my doctor advised me to wear sunglasses so that no one else gets infected.
I wonder how it happens that if someone looks into an infected eye, then there is a chance for that person to also get infected. Specifically, why does this apparently happen only when we see an infected eye?.
Another question I have is why does our eye get watery when we see the eyes of an infected person?.

The sunglasses are worn because eyes that are infected are more sensitive to light.  It has nothing to do with infecting other people, and has absolutely nothing to do with someone catching the infection while looking at the eye.

Then why did you provide us that image!?

@HarshalGajjar I have provided the image firstly because I was to make sure what I am asking, I mean, many of us has suffered this but only few are there who know its real name secondly to support my second question that why does our eye get watery when we see the eyes of an infected person?.

I'm affected now! //sarcasm :D anyways nice question.

Also sunglasses prevent dust and wind from irritating the eye..

You can't catch infections just by looking at the infected area but you can catch infections through touching, breathing of person, etc.

Why just repeat what was already stated in an answer that was voted on 17 times by the community; notwithstanding the fact that this is a question that is 2 and a half year old?

You can't catch conjunctivitis by looking at someone, but you can spread it around by touching your eye and touching something else, which then can pass the virus to someone else (viral conjunctivitis can be highly contagious). There are no hard facts, but one estimate is that people touch their faces an average of 3.6 times per hour, more if your eyes are itchy. Wearing sunglasses can not only help the possibly increased sensitivity of eyes with conjunctivitis, but they may also cut down on the number of times you touch your eye (thus spreading the virus).
There is no evidence to support that our eye get watery when we see the eyes of an infected person.
Conjunctivitis (Pink Eye) - CDC
Stop Touching Yourself, Flu Researchers Say

I have been old that door handles, armrests and other shared things are likely to transfer infected tears to uninfected eyes. Is this true?

Yes, it is. Hard surfaced like door handles and pencils can transfer the virus. That's why it's important that the person with conjunctivitis avoid touching his eyes, and should wash his hands frequently.


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What does irregular heartbeat mean in simple language?
I bought a blood pressure monitor (A&D UA-851) which has the option to measure irregular heartbeat.  I do understand what 'irregular' means, but why do irregular heartbeats happen and what are it's implications short and long term?

I wouldn't put too much trust in the option to measure irregular heartbeats. Its specificity shouldn't be too high, especially when you consider that some more advanced digital monitors used in hospitals give a lot of false positives.

I understand the OP wants to understand how his blood pressure monitor works. Some of you are thinking that it works by just interpreting cardiac rhythm. This is false! It is done by interpreting the frequency space of regular/irregular heartbeats. Please, note the difference between irregular cardiac rhythm and irregular heartbeat.

Masi - I understand something completely different from the question. He is not asking how his blood pressure monitor works, he is asking in layman's terms why an irregular heartbeat happens. I haven't voted your post down, but I think if you answered the question and were less confrontational and aggressive in comments you may get more upvotes.

I think you should re-think the accepted answer for one of the other answers.

@dustin are you telling me what to do? I understand Masi's answer and see that he's passionate about answering it right.

Is that rethink means to you?

The normal cardiac cycle is comprised of two distinct phases: the systolic phase in which the heart contracts, ejecting the blood, followed by the the diastolic phase when the cardiac muscle relaxes, refilling the heart with blood.
This cycle is assured by specialised cardiomyocytes (Cardiac muscle cells) that conduct electrical impulses through the heart. When there's interference in this electric activity, the cycle becomes irregular or arrhythmic.
Arrhythmias can be divided by their place of origin:

Atrial (atria are the upper chambers of the heart)
Ventricular (ventricles are lower chambers of the heart)
Junctional (the junction between the two)
Heart blocks (caused by a blockade in the conductivity of the electrical specialised cardiomyocytes)

Some arrhythmias are physiological, such as the Respiratory sinus arrhythmia, a naturally occurring variation in heart rate that occurs during a breathing cycle. Also, in healthy individuals, some extra sistoles might occur without being the translation of a subjacent heart condition and have benign prognosis in individuals without other conditions.
However, some arrhythmias can have a wide range of health implications, from asymptomatic, to a mild intolerance to exercise, to Cerebrovascular Accident (CVA or stroke) or even sudden death due to cardiac arrest.
Therapeutic varies with the underlying cause but can be medical (with drugs such as Na+, K+ and Ca+ channel blockers, beta-blockers and Digoxin) or surgical (ie: Artificial pacemaker).

Great answer but it would be fantastic if you added some references.

-1 This answer is about the origin of the cardiac rhythm with major simplifications in the cardiac cycle. Irregular heart beat is not the same thing as arrythmias, also dangerous overloading of tachycardia with arrythmia. Focus on the explicit classification of heartbeat based on origin, not how those machines work.

I think it's a very good answer - although references would be ideal all the content is factual as far as I can see.

@RoryM I recommend you to study little more Physics and Mathematics if you want to understand the big flaws in this answer. He does not answer to the main question explicitly what is irregular heartbeat. He does not try to explain how those machines work. This answer is biased and not useful to understand how the electronic device can do the analysis of the heartbeat, particularly of irregular heartbeat. You make extremely big simplifications if you do the analysis of the blood pressure based on these implicit facts, just ignoring the frequency space completely.

@Masi well, this is a Biology Q&A site so answers should really focus on the biological aspects of the question.  The original question "why do irregular heartbeats happen and what are it's implications short and long term" is succinctly answered in the above without over complication.

@RoryM This is Biology Q&A also for researchers! Not just for high-school students and for repeating pieces of information found in books.

@Masi What on earth does "dangerous overloading of tachycardia" mean? (I don't even mention tachycardia anywhere!)

@Tivie Yes, you are right. Arrythmias are rarely benign. I get an interpretation that there is a risk of going into tachycardia in your answer: "Some arrythmia are physiological" and then you describe situation tachycardic processes as arrythmic which is not necessary. This I call overloading which can confuse.

Very simply putting, irregular heat beat means that the pulse is not regular. It can be diagnosed by checking your pulse clinically.
Irregularities are further classified as:

Regularly Irregular: this occurs in heart blocks where every second or third beat is skipped regularly causing a pattern. Usually as time progresses the degree of block worsens and result in the final form which is complete block (fourth degree heart block)
Irregularly Irregular: this occurs in arrhythmia where there is total dissociation between atria and ventricles and the ventricles beat very irregularly with no pattern. The ventricles don't follow intrinsic rhythm because every SA nodal impulse that occurs at the end of latency of AV node will get conducted. Thus the heart rate is very high without any pattern. (Here heart rate means ventricular rate)

-1 because it is not correct answer to the functioning of the blood pressure monitoring. This answer emphasizes the melodies that are events in time interval of the heartbeat. There are also irregularities in the amplitudes of the heartbeat. There can be many amplitudes or energy levels in one heartbeat. Those machines do not only consider cardiac rhythm in making the diagnosis. They consider the energy levels and cardiac rhythm together. Without energy, you cannot even get pressure!

@Masi, you cannot measure irregular heart beat using blood pressure. Even a BP monitoring machine can measure irregular heart beat using pulse only. The only other way is using an ECG or echo cardiography. Irregular heart beat is a defined medical term. And my answer is the correct one.

Think a moment what you say, please. You have no references. You only assert. You cannot distinguish between subjective and objective measuring systems in your answer and comment, it seems. You exaggerate by using word only many times, which gives me a signal that you do not know this field well.  ECHO is the golden standard for the dynamics of the heart, but please remain in the topic and do not go sideways. We consider here personal blood pressure monitoring systems like pointed by the OP.

http://www.m.webmd.com/heart-disease/guide/heart-disease-abnormal-heart-rhythm what I said is correct. No one measures irregular heart rate using bp. Bp measuring in a patient with irregular heat rhythm is only done to prevent shock. Echo cardiogram can visualize heart beats thus irregularities can be seen and diagnosed. Please check thoroughly before telling someone is wrong.

Please, stick to the topic here. The topic is about what is irregular heartbeat and how the blood pressure monitoring devices work. Not about deducing irregular heartbeat from blood pressure. You confuse in your comment now also heart rate and heartbeat too. Please, read carefully before asserting again. Also, please use trustworthy sources like Harrison, Merck's manual and some publications. Your webpage is not a good source.

@masi you are incorrect. Read the OP again. It states that OP bought a BP cup, it has a setting, and then ask what are the implications of an irregular heart beat. That is, the fact they own a BP cup is irrelevant.

@dustin Last sentence is arrogant in your comment. The question has many parts. Some answers have focused here on explicit implications. This thread should be split in many parts to answer it completely. Heartbeat, how the device detects it and what the irregularity of the heartbeat mean.

@Masi read the sentence how you deem fit. The question is clear cut. From your profile, it says you are in medical school. Then you should know from case studies that there is information put in them that is irrelevant. When you do your differential diagnoses, I hope you don't include the useless information. The same is occurring here. The question is: why do irregular heartbeats happen and what are it's implications short and long term? The question came about due to a setting on a BP. The question doesn't say anything about relating the two.

@dustin This forum is not for medical advice! I do not even write such answers here. This is for understanding in Biology which means real world and living organism. This requires understanding. Yes, I understand how the question comes. To explain how the measurement result comes is one point here - it is just an approximation from the machine which can have many designs. To explain the main question in the title is another thing too. Third thing is about indications. 4th thing is about implications from subjective results which should not be made, since this is not for medical advice!

@Masi no one is saying give medical advice. Read my comment one more time. Again, I am telling you to re read something.


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Is there an advantage to having cellulite
There are many ads nowadays advertising cellulite removal, and it causes me to wonder if there is an advantage to having cellulite or if it is just a result of too much fat unevenly spread?  Is it structurally more efficient at storing energy or providing insulation?

There's no advantage or disadvantage (beyond personal perception of attractiveness).
It's a benign condition that can occur with hormone changes, weight changes, and especially genetic predisposition.
It occurs in most women (up to 90% will have it at some point) and some men, and physicians consider it 'normal.'
http://www.mayoclinic.com/health/cellulite/DS00891


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What is the effective relatedness of inbreeding?
If a human inbreeds with a relative, how distant does the relative have to be before the homozygosity in the child is no higher than if the mate were randomly chosen from the global population?

The easiest and most simplistic way to look at it is to assume that the amount of genetic material halves each generation.  On average, humans are about 0.1% to 0.15% different from each other, so in order to get that you'd need around $1/2^{10}=0.0976\%$ and $1/2^9=0.1953\%$. The exponent numbers $2^9$ and $2^{10}$ are 512 and 1024, respectively.
Armatus' Dawkins bit is almost word-for-word what he actually said:

By the time we get to third cousins, "we are getting down near the baseline probability that a particular gene possessed by A will be shared by any random individual taken from the population".

Dawkins was ball-parking that a bit, although he was really talking only about a specific gene.  The inbreeding coefficient is properly defined as:

The probability that an individual carries two identical-by-descent alleles at a locus.

Which takes care of some of the fudging.  With that in mind, though, within eight generations the odds are less than even you even share any genetic material with an ancestor/offspring. That's actually a mathematical analysis (with plenty of assumptions!) from the mid-80s but it's an interesting read: you can look up values for certain relations going back a bit.  The answer will vary depending on the background "average" you care about.  Europeans, for example, are particularly closely related.
Indeed, "[g]enetic variation is geographically structured, as expected from the partial isolation of human populations during much of their history."  If you want a perhaps easier-to-read explanation of some of the math, I would suggest this 2006 review, in particular box 2.  From that, a silly back-of-the-envelope calculation from 0.1% related gives a path of around 10 individuals, which is a little more distant than your third cousin.

In "The Selfish Gene" Dawkins claims a relatedness factor of 1/128 to be pretty much the same as the baseline chance for the rest of the population to have the same gene, so that would be a third cousin. (Or your great great great great great grandparents, though an incestuous relationship with them is quite unlikely I think.)
I'm not sure where he got that from though.


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Why are transcripts translated from 5' to 3' direction?
What is the mechanism?
In other words, how does the tRNA know whether the codon is in 5' to 3' direction? I also heard that anything that is translated from 3' to 5' direction is degraded. Is it true?

Related: Why does DNA replication go from 5' to 3' http://biology.stackexchange.com/questions/477/why-is-dna-replication-performed-in-the-5-to-3-direction

The tRNA is not acting alone, it has the help of the Ribosome.

The Ribosome assembles at the beginning of the transcript and starts the translation at the first AUG codon. It then binds the first tRNA which fits to the mRNA. The tRNA is then moved from the A-position to the P-position and the next tRNA is binding (the move around and bind by chance. A nice animation is found in the Wikipedia article on translation (which is also the source for the image above).
Translation can't go into the other direction, it is always in 5' -> 3'.
To recognize the right direction (and the right starting point) the Ribisome is not simply starting at the 5`end of the mRNA. Before the start codon AUG the mRNA contains a regulatory, untranslated region, the so-called 5'UTR. The end of the 5'UTR of eukaryotes contains the so called methylguanosine cap (and is only present in mature mRNA), in proaryotes this is done by the Shine-Delgano sequence. Both are recognized by the ribosome. After binding to the mRNA, the ribosome slides along the nucleotide chain until it reaches the first AUG to initiate translation. The image is from this description (which contains a lot more details, if you are interested in it).

Thank you for your answer. But how does the Ribosome "know" that the beginning is THE beginning? What if sequence is flipped 180 degrees? if you look at the mRNA as a string of sequence, say AAAUUG, then the beginning can be either A or G, because if you flip the sequence, it's GUUAAA.

@Alby I edited and expanded my answer.

I think that there is no reason in principle why early evolution couldn't have landed on a translation mechanism going 3'>5'. There are, however, clear biochemical reasons why the transcript itself has to be made in a 5'>3' direction. So in this alternative world where the initiation signals would have been at the 3' end of the mRNA, the message would have to be fully transcribed before the anti-ribosome could bind to these initiation signals.
In bacteria at least, translation is initiated at the 5' end of the mRNA even as it is being synthesised, and this rapid transcription>translation link may offer some advantages.

I don't think this happens in eukaryotes, since the mRNA has to be processed and exported from the nucleus.

Agreed, but I'm assuming that the bacterial system is closer to early life.


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What is the most stable globular protein?
What is the most thermodynamically stable globular protein?
I am looking for a small (ideally less than 50kDa) soluble globular protein motif which folds easily/reliably and is known to be extremely stable and resistant to unfolding once folded.  Also very resistant to proteolysis and degradation.
Any ideas?

ubitquitin is very stable, you could double check, but my supervisor was saying that people initially thought it wasn't a protein because it was so heat resistant

RNAse A was used to prove that a protein's structural information was stored in its sequence by unfolding it and refolding it, so it must be pretty stable. I've also worked with Bee Venom PLA2, which has 5 disulfide bonds. It's so stable, I've left solutions out on the bench over the weekend and the activity wasn't harmed at all. I've conjugated the protein with peptides and/or oligosaccharides with minimal activity loss. I've iodinated the protein under harsh conditions and retained 25% activity.

After I left the lab, another student has been able to pass Bee Venom PLA2 through an HPLC column with an acetonitrile and dilute TFA gradient ( the same kind you'd use for small molecules ) and recover the enzyme with full activity. It's really stable. As for MOST stable, that's probably a thermodynamics problem. These are just my anecdotal experiences with a very stable enzyme.


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A compound was proposed by error but then showed very good inhibitory properties. How to argue this in a manuscript?
In a project, we performed some virtual screening calculations in order to predict inhibitors, and then purchased the compounds and tested them in the lab. One of them was a very good TK inhibitor (IC50 nM).
However, when we processed the results we realized that the presence of this particular compound in the original list of virtual screening hits was due to errors in the original calculations (it was added to the list by random factors, not by docking score).
So now we are writing the paper and we wonder how to argue this. We can not just tell the story like in this post (it was discovered by randomness or by our error). How would you argue this?

It was in your negative control set and it worked. I have had a lot of random mutations in my library designs which I did not plan on end up working. You just say it in the results section and don't try and matriculate on it too long. That is only possible if you have real molecules from the docking data that also worked. If that is so, you can definitely add this as a fluke and no one will argue. However, if it is the sole result and conclusion, it may be much harder to spin a high impact manuscript.

I'm voting to close this question as off-topic because it is about the process of submission of papers to journals and not about biology itself. Any answer is also subjective.

@David yes, [academia.se] might be a better home for this. On the other hand, an understanding of the basic biological concepts involved is helpful for answering. I think it could go both ways.

Be honest (and possibly split the papers).
If the compound was identified as an error and you want to include in a paper describing the process of your simulation and the effectiveness of the predicted inhibitors, you'd have to do so as a sort of negative control for your calculations (unless there is some way to reproduce/rationalise why it showed up randomly). Since this is the only good inhibitor you have, you'd have to conclude that your calculation isn't much better than chance, or explain why it is better even though you found a better inhibitor by chance. If you have reason to argument that your calculations are good and make sense then exclude the 'random' inhibitor from that paper. You can the write an individual paper about a good inhibitor, the fact that you found it by chance isn't that important anymore.


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Well to well variation in thermal cycler fluorescence?
We have an old BioRad ICycler Thermal Cycler with MyIQ single color fluorescent detector. While it's meant for RT-PCR, we've been using it for melt curves and binding assays for different types of RNA using thiazole orange as the intercalating fluorophore. However, when we tried to get serious about this assay and do things in triplicate we noticed that the well to well variation was terrible, making statistical significance difficult to get.
After reading through the manual I tried to get "persistent well factors" for the instrument to correct for this variation. However, the instrument's protocol for this requires heating to 95⁰C, so intercalating fluorophores won't work, the RNA melts and fluorescence is lost, so I tried with fluorescein. This didn't solve the variation.
So I tried to make my own well factors by making 10mL of Poly(rA) Poly(rU) RNA solution with thiazole orange and filling 96 PCR tubes with 100µL each and measuring fluorescence. Then I calculate the average fluorescence and divided the average by the value for each well to determine a factor, F, for each well. Then I tried to normalize subsequent experiments by multiplying each well's fluorescence by its F to get a corrected value. However, while this reduces the variation a little, it's still pretty bad.
Do you have any suggestions to reduce the well to well variation in these experiments or otherwise correct the data?
I have no prior experience with RT-PCR instruments, everything I know about it comes from playing around with the instrument. I don't know if I'm missing something really basic.
Step by step protocol

Prepared 1xSSC buffer, 150mM NaCl, 15mM Sodium Citrate, pH 7.5
Weighed 5mg Thiazole Orange, dissolved in 1mL Methanol
Diluted Thiazole Orange 1000 fold in 1xSSC
Took 71.4µL (100µg) Poly(rU) Poly(rA) solution, 1.4µg/uL
Diluted RNA with 8.93mL 1xSSC
Added 100µL diluted Thiazole Orange to diluted RNA, final volume 10mL
Set up 96 PCR tubes, used 8 channel pipette and trough to transfer
100µL RNA solution to each
Placed PCR tubes in all 96 positions of thermal cycler
Ran melt curve protocol, start at 25⁰C, increase 1⁰C every cycle,
60 cycles, so final temp is 85⁰C. Each cycle is 10 seconds.
Measure fluorescence every cycle.
Repeated melt curve 3 times, total of 4 curves.
Put data from each curve into spreadsheet. 96 data points at each temperature.
Averaged fluorescence across the whole plate at each temperature.
Used this average, standard deviation, maximum, and minimum
values to make the plots below.
Calculated correction factors for each well at each temperature by
dividing the whole plate average fluorescence by each well's
fluorescence for melt curves 2, 3, and 4. Averaged correction factors from each curve.
Calculated corrected fluorescence for curves 1, 2, 3, and 4 by
multiplying the averaged correction factor for each well by the
observed fluorescence for that well.
Replotted the corrected values to show reduced variation.

Data is shown below. I repeated the melt curve 4 times because the first melt usually has a lower intensity than subsequent melts. Y axis is fluorescence, X axis is temperature in celsius, and I plotted the average fluorescence at each temperature with the standard deviation along with the minimum and maximum to show how far outside the standard deviation some wells are falling. I calculated the correction factors for melt curves 2, 3, and 4 and averaged them. When I used these averaged factors on melt curves 2, 3, and 4 it did a good job at eliminating variation. When I applied the correction factors to melt curve 1, it reduced the variation, but not by much.

Are you sure that part of the variance is not due to the processing of the triplicates? How do you prepare them? This is a very important factor and a serious error source.

@Chris edited the question to include how I prepared the samples.

@user137 In questions like these it is best to describe the protocol that you used, step-wise.

@WYSIWYG A step by step protocol has been added. Feel free to ask about anything that isn't clear.

@user137 There should not be any necessity to do a well to well fluorescence correction. There should not be variation from any source other than handling. Is your machine serviced and all?

@WYSIWYG The variation exists despite trying to minimize variation by creating 1 large batch of solution and using a multichannel pipettes. The bright wells and dim wells seem to be the same wells in every experiment. The machine is not serviced at all, we don't have a service contract and I don't think I could convince my advisor to pay for maintenance.

@user137 I have had troubles with multichannels. sometimes the tips don't fit properly and it causes variability. In any case there are more sensitive equipments for melt curve analysis. In qPCR machines the lamp also has to be replaced after some time (it has some 'life'). Is this not a crucial experiment? All I can suggest is do another meltcurve experiment with a different concentration (or whatever parameter you want to change) and see if the inter-well variance makes the difference statistically insignificant. If it doesn't then go ahead with the experiment.

@WYSIWYG Thankfully it's not a critical experiment yet, and won't be for me because my thesis is finally almost finished. However I suspect my advisor will want the new student taking on my project to do a lot more with it. I'll see about the lamp replacement because I'm pretty sure it's never been replaced and the instrument has to be 10 years old.

@user137 Do these comments kind of answer your question?

@WYSIWYG They've been helpful, probably as close to an answer I can get without bringing you to the lab to debug it in person.

There can be several reasons for variability and since you said that the machine has not been serviced for a long time, I guess that should be one main source of errors. Multichannel pipettes can also sometimes cause problems (based on personal experience) and it is mostly because the tips don't fit properly in all channels.
Try varying some parameter (for e.g. concentration of RNA) and see the effect on melting temperature; if the inter-replicate variability is not high enough to make the inter-sample difference insignificant then you can continue with your experiment. Take more number of replicates to minimize variance.
If the variability is very high then I guess you would need to get your machine repaired or use more sensitive equipments designed specifically for these kind of studies.


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Body's decomposition
Does a human body decompose in a completely sterile environment ? If yes, what decomposes it ? And how fast ? What happens in vacuum ? Can it remain exactly the same ?
Thanks

In vacuum for example?

In vacuum, exactly.

Does a human body decompose in a completely sterile environment ?

No it wont. Unstable molecules like ATP will quickly degrade spontaneously. The stable ones like many proteins and lipids wont degrade spontaneously. Enzymes are essential to degrade them and are to be supplied extraneously.

What happens in vacuum ?

Body will dry up :P


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What would happen if VEGF was injected into a person?
Couldn't VEGF help with ligament recovery? I looked it up and found some studies in rats, but nothing on people. VEGF inhibitors tend to be used more often then VEGF.
Why isn't VEGF being used in people? What would generally happen if VEGF was injected into a person?
EDIT
Here is the one study that examined injection VEGF in rats for increasing skin viability.
Also I am not really asking about the effect of VEGF on ligaments. I just figured that because there is little vasculature surrounding ligaments (and cartilage), VEGF could in theory improve recovery of such injuries. The bigger question is why aren't people ever injected with VEGF?

VEGF is a family of growth factors that promote angiogenesis and vasculogenesis.
Vascularization is a key step in the progression of cancer, so the VEGF family has often been a target for suppression: preventing vascularization of tumors can stop their further growth.
That said, your premise that VEGF hasn't been tried clinically is false: there have been several clinical trials of VEGF (and no doubt more that I didn't find).
Hedman, et al 2003 used catheter-based VEGF gene transfer at the time of angioplasty/stenting, though they found it did not prevent restenosis they did see increased perfusion (it seems to me that further research didn't show sufficient effects on long-term outcomes). Ripa, et al 2006 used VEGF gene transfer as part of a treatment for ischemic heart disease. It seemed like the treatment was safe, but the efficacy was limited. Ropper, et al. 2009 attempted VEGF gene transfer for the treatment of diabetic polyneuropathy. They found some improvement of pain, and report a fairly high rate of adverse events but their control group also experienced adverse events.
It seems like a similar VEGF plasmid is available in Russia as Neovasculgen for use in limb ischemia; the company developing the drug is in the process of beginning to get approval elsewhere.
VEGF as a topical application has been studied under the name telbermin, for example Hanft, et al 2008.
There may be others, but I stopped my search there. https://clinicaltrials.gov/ is a good place to start looking for what research has been done in humans if you have trouble finding journal articles at first.

Hanft, J. R., Pollak, R. A., Barbul, A., Gils, C. V., Kwon, P. S., Gray, S. M., ... & Breen, T. J. (2008). Phase I trial on the safety of topical rhVEGF on chronic neuropathic diabetic foot ulcers. Journal of wound care, 17(1), 30-37.
Hedman, M., Hartikainen, J., Syvänne, M., Stjernvall, J., Hedman, A., Kivelä, A., ... & Närvänen, O. (2003). Safety and feasibility of catheter-based local intracoronary vascular endothelial growth factor gene transfer in the prevention of postangioplasty and in-stent restenosis and in the treatment of chronic myocardial ischemia: phase II results of the Kuopio Angiogenesis Trial (KAT). Circulation, 107(21), 2677-2683.
Ripa, R. S., Wang, Y., Jørgensen, E., Johnsen, H. E., Hesse, B., & Kastrup, J. (2006). Intramyocardial injection of vascular endothelial growth factor-A165 plasmid followed by granulocyte-colony stimulating factor to induce angiogenesis in patients with severe chronic ischaemic heart disease. European heart journal, 27(15), 1785-1792.
Ropper, A. H., Gorson, K. C., Gooch, C. L., Weinberg, D. H., Pieczek, A., Ware, J. H., ... & Kirchmair, R. (2009). Vascular endothelial growth factor gene transfer for diabetic polyneuropathy: a randomized, double‐blinded trial. Annals of neurology, 65(4), 386-393.
Simovic, D., Isner, J. M., Ropper, A. H., Pieczek, A., & Weinberg, D. H. (2001). Improvement in chronic ischemic neuropathy after intramuscular phVEGF165 gene transfer in patients with critical limb ischemia. Archives of neurology, 58(5), 761-768.

These are interesting articles. However, they all appear to be utilizing gene transfer therapy methods rather than hormone therapy. Are you sure you found studies that utilized VEGF and not VEGF plasmids?

@JHouseman That seems to be the typical approach. The Hanft paper is VEGF itself rather than plasmid, you can find more searching telbermin. As you'll note in the cardiac work, part of the point is to have VEGF present where needed, such as the site of angioplasty, and also the desire to have VEGF present over a long time period, hence the use of plasmids. It may be easier to inject VEGF directly in an animal study where the animal is always in the lab, but not really feasible for human use.


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How do I know whether or not a nuclear gene is single copy?
As a part of a phylogenetic study, I need to find a nuclear gene that meets the following requirements:

Single copy gene;
Highly variable gene;
Gene longer than 400 bps;
Gene that gives information at the species/genus level in Gastropoda.

My candidate genes are the following: 5.8S, 18S, 28S, ACT, APN54, EF-1alpha, endo-1,4-beta-glucanase, GSTM, GSTO, GSTP, H3, ITS1, ITS2, MCP, MYO.
However, I do not know where to find whether or not they are single copy.

Even simpler: If you are lucky and your target Gastropoda is in Ensembl (http://ensemblgenomes.org/) you can just introduce the gene ID and see if it has any paralogs. A lot of other info is available for each gene.

The simple way to do this is to use blast to search the genomes your interested in for sequences similar to your gene. If there's another copy it'll turn up in the blast results (so will orthologous genes - but they'll have lower scores than an actual copy). That relies on the annotation and genome being correct, of course.


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Ways cancer cells spread through blood
If I understand correctly when tumor grows, it can reach blood vessel and then spread through it to another organ - it called metastasis.
How do cancer cells then are spreading through blood? Do they just flow the same as another  blood cells? Or maybe they connect to erythrocyte and drive on them?
Also, it will be useful if you provide metastasized cancer cells sizes, at least ranges

Sorry I'm having a hard time understanding how the first sentence connects with the rest of the question... What is the relationship between angiogenesis and metastasis?  Also, you'd be better to narrow it down quite a bit... "Cancer" is a huge subject with tons of different types.  Please [edit] to clarify

@rotaredom, sorry maybe I used wrong words, English is not my native language. Is it more clear now for You?

A short and abbreviated summary:
When tumors grow to a certain size, they will start to develop a "tumor microenvironment", which is a umbrella term for all kinds of cells and tissue beneficial to the tumor, in most cases fibroblasts (cancer-associated fibroblasts) and macrophages (tumor-associated macrophages), but it depends on the specific kind of tumor and its organ.
As tumor cells exhibit a drastically increased metabolism, they will begin to suffer from hypoxia (low oxygen concentration), which is signaled via several different biochemical pathways to the microenvironment and leads toward angiogenesis, the creation of new, often malformed, blood vessels, towards the tumor mass.
The tumor can now increase its mass further due to the continual metabolic supply and the cells can undergo a process called "epithelial-mesenchymal transition", which will allow the tumor cells to "detach" themselves from the primary organ (intravasation), enter the blood system and colonize "pre-metastatic niches" => new tissues and organs.
Some tumors are able to prime distant organs for metastasis via the secretion of specific factors and in many cases tumors show a distinct preference to metastasize in particular organs.
Sources:
Ralf et al (2007): Molecular regulation of angiogenesis and lymphangiogenesis
Costa-Silva et al (2015): Pancreatic cancer exosomes initiate pre-metastatic niche formation in the liver
Egeblad et al (2010): Tumors as organs: complex tissues that interface with the entire organism
Bu et al (2019): Biological heterogeneity and versatility of cancer-associated fibroblasts in the tumor microenvironment
Jang et al (2019): Integrins, CAFs and Mechanical Forces in the Progression of Cancer

Thank You, this answer is informative and useful, but, unfortunately doesn’t directly answer the question (minus not from me)


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Can anyone give me the common name of this flower/vine?

Photo taken in NYC in April 2017

I think this is Kerria japonica (L.) DC, in it's less common non-filled form.

I think this is Rosa foetida, the yellow rose. Unfortunately the leafs are not visible very well but the flower, together with the growth, is pretty characteristic. See this image (from here) for comparision:

The German Wikipedia also has a drawing of the plant (from here):


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How might I break down bread into glucose in a model of the human digestive system?
I need to make a model of the digestive system. It would be really nice to actually show it in action, such as by breaking down bread into glucose or something similar. Is this feasible with a small budget and non-dangerous chemicals? If so, how? This should be as similar too the real digestive system as possible.

Isn't this an exact duplicate of the question you asked a couple days ago?  http://biology.stackexchange.com/questions/2385/what-is-an-simple-way-to-burn-glucose-for-visible-effect

@mikemanne: I'm asking about how to break down starch into glucose. Before, I was asking about how to do something with the glucose obtained from this. The answer to one is apparently Amylase, while the answer to the other is some kind of  combustion or something like that

Amylase would be worth a try. The enzyme breaks down bread (starch), and you can buy it relatively cheaply online or probably at a chemist. Amylase is secreted in your saliva and in your stomach, so it would be most realistic if it was added in your model at those two points.

Would have thought you'd need some mechanical action to break down the bread too

If you just keep some bread crust in your mouth without chewing, it does become sweet at some point. You will just be waiting for quite some time... I spent a whole school day with bread crust in my mouth XD Adding the mechanical action might be hard in a model.

@Armatus: Great. About how much time would it take, and what could I do with an glucose solution?

That depends on the concentration you use. I would aim for a ridiculously high concentration to try and get it done quickly. As for the resulting glucose-containing solution... I don't know, you could pump it out of the model stomach around the rest of the model?

I think the easier strategy would be to use saliva and coca-cola. It's a very visible process.

@bobthejoe: How would that work?

@Armatus: how much is ridiculously high?

@Armatus: I was told that amylase is only capable of starting the breakdown process, and the pancreatic and instestinal juices were responable for actually turning it into glucose. Is this true?

<en.wikipedia.org/wiki/Amylase#.CE.B1-Amylase>: it breaks starch (amylose/amylopectin) into maltose and possibly glucose (amylase is the part of pancreatic juice that digests starch). I suppose you would try to dilute it as little as possible from how you buy it. I'm speculating though, I'm not sure how realistic it is to use amylase in your model.

@Armatus: Wanted to ask you for more help, but wasn't sure how to, so I'm using this. I saw that amylase came in a couple of types and required some stuff to function (at the very least, calcium). What are the types that I need, what exactly do I need for them to react properly (and in what order, etc)? Also, do you by any chance know where I might order the correct amylases so that they would arrive in time to do it before this friday (8th of june)? I live near Montreal. Thanks a bunch for your help.

@Armatus: I was also told about Fehling's solution as a way to show the broken-down glucose, but that seems hard to make. Are there any simpler methods (I heard povidone-iodine reacts to starch)? Ones that actually do something, preferably, but time is far more important than rightness.

Googling brought up this: http://www.wineandcake.com/browse.cfm/amylase-enzyme-1.5-oz/4,7911.html (for $2). Unfortunately I can't really help you beyond this, I haven't used amylase myself. For staining starch there's Lugol's solution but that seems to be more expensive ($20).

@Armatus: Are you certain that that is the right thing? I note at least two varieties thereof. Which one do I want?

Also, I just realized that I have Lugol's iodine at home as a disinfectant.

Also, that does not ship to canada, at all.

Finally, how might I arrange for these? http://en.wikipedia.org/wiki/Alpha-Amylase#Optimum_conditions_for_ptyalin

How would I calculate how much time it would take for the reaction to happen?

The pancreatic alpha amylase should be what you want. I can't really tell you anything for certain because I haven't done this myself; if you think your model is worth it you will probably just have to try (unless someone with experience in this replies). In order to reduce the pH you could try adding some weak acid like citric acid (lemon juice). It's near impossible to calculate the time accurately because you don't know your exact conditions.

@Armatus: brewers say nothing about what type of amalyse they have have, and 'pancreatic amlyase enzyme' gives me lipase and protease mixed in. Although maybe that's not so bad?

That shouldn't be a problem, in fact if the fat and protein content is digested as well the result might look nicer.

Generally speaking and as suggested by Rory, mechanical force probably plays a role in most instances (crustless bread may be different):
http://www.modelgut.com/dmg.html
I was hoping to post more about this but the websites of one of the institutes involved in developing the model gut doesn't provide much accessible information on first read.
Maybe this still gives you something of a starting point:
http://www.ifr.ac.uk/info/about/index.htm


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Hardy-Weinberg applied to three alleles and stimation of allele frequencies
I have this equation:
Corresponds to HW in equilibria with three alleles:
$(p+q+r)^2=1$
Expanding the square results:
$p^2+2pq+r^2+2pr+q^2+2qr = 1$
I need to separate homozygous and heterozygous, that means:
$2pq+2pr+2qr=1-p^2-q^2-r^2$
How I can use a equivalence similar to $(p=1-q) or (q=1-p)$ in two alleles to resolve the last equation?

in this case it will be r=1-p-q and similarly for others

Why do you need to separate homozygotes from heterozygotes?

I'm with jkadlubowska - what's the purpose of separating hetero and homozygotes?

To calculate the proportion of the alleles (p, q and r), if the homozygotes are three times than heterozygotes.

So you omitted some data of this question? The thing is, you can substitute whatever you want, e.g. 1-p=q+r or p=1-q-r, but that leads you nowhere if you don't have any more data. Something like p^2+q^2+r^2=3pq+3pr+3rq is crucial to solving this problem. Anyway - these are two equasions, you still need a third to ba able to assign specific numbers to p, q and r.

i think WYSIWYG has answered this question.  can't do much more unless you have a further answer you are looking for

I agree with jkadlubowska that some information is missing.  If you want numerical values, the number of equations must be equal to the number of variables.  Otherwise, the best you can do is solve for two variables in terms of the other. Did you want to do that?

Everybody said it already, but there is none.  The original HWE equation ($(p+q)^2=1$) works because you've got two variables and two equations ($p+q=1$) to work with (in reality, these are just one equation and one variable, since $q=1-p$ so $p+(1-p))^2=1$).  Now you have three variables and still only the one equation ($p+q+r=1$) which is, mathematically, impossible.
You need go out and measure some frequencies.  In particular, you need to measure two of them - I'd choose two of the homozygous types for convenience's sake.
This basically summarizes everything nicely for ya: http://www.bio.miami.edu/dana/dox/trinomial.html

mathematically impossible -> mathematically insolvable.  Its quite possible.


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Is there a function for urea in sweat?
In ureotelic organisms, ammonia is converted to urea for excretion primarily in the liver and, to a lesser extent, in the kidneys. However, sweat also contains trace amounts of urea. Is this small amount just a residue from the blood or is it produced in sudoriparous glands and is, therefore, an adaptation (a backup route in case of liver/kidney failure, or maybe it has a function in chemical communication, as a pheromone)? Or does it have another, maybe vestigial, function?
Is there a function for urea in sweat? If so, what is it?

Tl;DR: Urea is a metabolic waste excreted from human body. As such it does not have any function in human body. It is a major product in the waste excreted from kidneys although trace amounts can be found in sweat. The concentration of urea increases when kidneys fails to function normally. Hence, they are excreted through sweat glands, observed as "frosts" on the skin among uremic patients.
Long answer:
Urea is a normal metabolic waste which are excreted by the kidneys but are also excreted from human body via sweat. In fact, sweat contains trace amount of urea, about 22.2 mmol/L (Huang.et.al. 2002; More on the concentration of urea in thermal sweat has been discussed by Bulmer, 1957). Urea is excreted by eccrine glands. As such, it is also thought to be an excretory organ (urea transferred across eccrine glands is discussed by Komives. et.al, 1966). However, the concentration of urea and uric acid doesn't affect much in the homeostasis function (as they are in negligible amount compared to metabolic waste in kidneys. Sweat seems to play the role of thermoregulation):

urea readily crosses the eccrine glandular wall and cell membrane and therefore concentrations of urea in sweat are expected to be about the same as that of the plasma. Some studies report very high urea concentrations in sweat , up to 50x that of serum, and suggest that this is evidence for a selective transport mechanism across the sweat gland, especially in patients with kidney damage, to clear the blood of high urea concentrations (Al-Tamer et.al., 1997).
[...]
Other studies have shown that uric acid and creatinine excretion via sweat is insignificant compared with elimination rates through the kidneys. Taken together, there is limited evidence that the sweat glands excretory function makes a substantial contribution to homeostasis.

As noted by Keller et.al. 2016, the concentration of urea and uric acid in sweat increases when kidneys fails to function normally:

In humans, urea is excreted in sweat, largely through the eccrine sweat gland. The urea concentration in human sweat is elevated when compared to blood urea nitrogen. The sweat urea nitrogen (UN) of patients with end‐stage kidney disease (ESRD) is increased when compared with healthy humans. The ability to produce sweat is maintained in the overwhelming majority of ESRD patients.

Also, urea concentration in sweat seems to be different among genders:

The sex difference in sweat UN was a surprising finding. In humans, the menstrual cycle is known to change the characteristics of thermoregulation and electrolyte balance. Estrogen lowers core body temperature at rest and during heat stress. Additionally, estrogen replacement therapy increases total body sodium.


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Which ant/wasp species is that?
Anybody knows which species (or genus, family...) of ant/wasp is that?

It's from Brazilian Amazon (Upper Negro River, Amazonas state). About 2-3 cm long (about one inch), maybe. It was walking on the sandy road around noon. Don't know the month of the year.

I think this is a Cryptus wasp, and from the googling I've done it looks very like Cryptus leechi, but I don't know which parts of the world that's found in.

It looks even more like Cryptus rufovinctus. OP, take a look at the Cryptus species on this webpage: https://v3.boldsystems.org/index.php/Taxbrowser_Taxonpage?taxid=213691 and see what you think.

@Astrid_Redfern I'm not sure, but the waist on mine has two segments, and the abdomen seems more like an Aculeata.

@Astrid_Redfern The wing venation is different too.

What do you think of this Cryptus albitarsis : http://www.knowyourinsects.org/Ich1_Sarah.jpg The legs are the wrong colour, but I can't tell whether one part of the image I'm seeing has the extra waist segment.

@Astrid_Redfern No. The waist, the tip of the abdomen and the wing venation are all different.

Great photo! I see 12 or 13 segments total on the antennae, so not Ichneumonidae (includes cryptus) which have 16 or so.

@PolypipeWrangler Thank you! Does this also exclude the remaining Ichneumonoidea? I'm not sure, but to me its abdomen looks like Aculeata.

Given the presence of a petiole and postpetiole, this is most likely a winged ant (drone or queen), such as this similar one here:
https://bugguide.net/node/view/57281

Indeed it looks like an Attini ant, though the antenna does not seem to be geniculate, and the first flagellomere seems to be the same size as the others. But that's probably just an impression, because the photo is not so clear.

For this to be an ant, the antennae MUST be geniculate ("elbowed"), with the first segment the longest (see here for some identification tips); this is not true of the OP photo.

I wondered about this too, and if this insects antennae had a very short elbow.  I couldn't quite decide from the image

@ArthurJFrost, this is what I was thinking regarding the scape:
https://cdn.britannica.com/s:700x500/21/188721-050-3D55AD79/leafcutter-ant-species-fungus-substrate-Atta-cephalotes.jpg
Rodrigo I do agree regarding the flagellomere.  What an intriguing insect you've happened upon!

Regarding the very short elbow - take a look at the very short "elbow" on the antennae of the male Monomorium minimum in this picture: https://www.antwiki.org/wiki/File:Monomorium_minimum_queen,_male,_Austin_Texas,Alex_Wild(1).jpg . Then look closely at the antennae on OP's mystery specimen - the antenna that's further away does appear to have a noticeable joint of some sort near the head. Perhaps the angle of the shot obscures such a joint on the closer antenna too. Anyway, I think these could be ant antennae, though not that species.

There's a similar short "elbow" and eleven-segment-thereafter antenna on this Dacatria templaris winged male: https://www.antwiki.org/wiki/File:Dacatria_templaris_male,_South_Korea,_Minsoo_Dong.jpg . Though otherwise that's even less like OP's photo.

Could be some other winged male ant of the Monomorium genus?

The "elbows" on male Crematogaster ants are even shorter - see http://cle.fourmis.free.fr/male-crematogaster-2.html and https://bugguide.net/node/view/1327317/bgimage

The head and jaws seem too small and weak to be an ant. The heads of ants are usually more shiny also.

@PolypipeWrangler It might be a male ant. "Male ants ... can be identified by their smaller heads and longer antennae." (https://www.naturalresources.sa.gov.au/files/sharedassets/adelaide_and_mt_lofty_ranges/nrm_education/amlr-native-ants-teacher-pack-gen.pdf). Or "males ... have smaller heads with bigger eyes and straighter antennae." (https://askabiologist.asu.edu/explore/ant-anatomy). According to https://antark.net/ant-life/the-ant-family/drone-alate-ant/ "Drones ... look more like wasps than ants." See the silhouette-style pictures at https://antark.net/ant-life/the-ant-family/ .

To clarify: I currently think it is almost certainly a winged male ant (drone).


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Are there organisms sensing conformations, which we humans can't sense directly?
Are there organisms which can sense the conformations, which we humans can't sense directly, i.e. without using any equipment?
If there are organisms which can sense conformations ("the shape or structure of something"; objects; example: elementary particles, atoms or anything) of sizes which we human's can't sense directly, can we know on what they are sensing, to compare on what is being known theoretically or by indirect means via equipment, for knowing them more precisely than before?
Sensing (in this context) = Knowing on how objects are at lower scale; knowing there shape, smell (!), taste, touch, sound, etc.
What is to be sensed? = It may be the properties of the conformations at lower scale, which may not be sensed directly by humans.
Organism (from wiki) = an organism (from Greek: οργανισμός, organismos) is any individual entity that exhibits the properties of life. It is a synonym for "life form".
NOTE: I had before asked on the organisms sensing conformations which humans may not have, even by using equipment. As the utility which is needed, is to know the elementary particles precisely, I have changed the question to know on organisms sensing the conformations which we humans can't sense directly, to compare with what is known from theory or equipment, and to know accurate details. And if I would have had limited the question to what organisms can sense which humans can't even by equipment, it seems to have become completely narrowed one, as humans, as said by others in the comments and answer, can sense most of smallest by equipment.

I am not a biology student, if there are sources which would allow me knowing on this, and if mentioned, it might help me.

Are you claiming that some species can sense individual protons and neutrons? I really don't understand your question. What can who sense? Are you claiming some species can sense something or are you asking if they could sense (hypothetically), then how would they do so?

Thank you for the comment. I am asking your last question if they could sense (hypothetically), then how would they do so?, and how to know on what they are sensing? This might give experiences for knowing on what QM,or any other elementary physics is trying to know.

I'm voting to close this question as off-topic because you question is based on a hypothetical situation that does not exist (and that is unclear btw) and it is therefore impossible to offer an answer that is empoirically inspired. You could give a try on worldbuilding.SE but you'll have to be way more accurate about the thing they can sense. You'll also have to be more accurate about the means of sensing. Humans can sense a whole lot of things with our complex tools (electronic microscope, LHC and others).

Sorry, I might have been not clear. I don't know on whether such organisms sensing lower scale conformations exist or not, and that is what I am asking in the main question; as said in my question, if they exist, only if they exist, how to know on what they are sensing? I might have misunderstood or not understood on the complete meaning of hypothesis, before mentioning it in the above comment. And organisms need not sense the extreme smallest elementary particles, I mentioned them as example, you can consider any small scale (atoms, compounds, etc) which humans can't sense....

So, your question is "Is there an organism that can sense 'such thing'?" and the you may ask as a follow-up how it is doing it. Make sure to be very clear by what you mean by sensing and what is the thing being sensed. Does the single proton sensing of humans count? Does electronic microscopy count? How small must the thing be that you want to sense?

Thank you for the comment. I have edited the question. I meant to say any conformation, which human's can't sense, even by using any of the equipment.

@Remi.b: I have changed the question.

Animals can sense magnetic fields

technically speaking, Large hadron Collider allowed humans to sense quite a bit of information about particles. Also, we can sense pretty well how electrons and photons behave, using other tools. We even can sense how they behave in absence of particles (it's called theoretical physics).
Closer to your point, however, it is verified that human eye (and brain) can detect single photons. There are probably similar studies about smells, maybe even electrons or electric currents.
My main point is that you need to specify exactly what you are asking. Right now it is unclear.

Sorry, if the question is not clear. I have edited the question now. If it is still not clear, can you please say on where I need to clarify?


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Which data source gives the present status of research in extending human lifespan?
I have seen this book in Springer:
The Future Of Aging (Pathways to human life extension)
That book seems to be of 2010; I am not finding any such new books, giving data on the present status of the research.
Which data source (journal articles, books, etc) gives the present status of research in extending human lifespan (longevity)?
I read Wikipedia (Life Extension, Immortality), they don't seem rigorous.

Are you asking for a more recent review paper/book of the topic?

Thank you for the reply. Yeah, I asked for a recent paper/book, to know on what conformations/actions in nutrition or exercise are to be made for becoming compatible for getting those life extending processes. I found certain summaries of the present status, which seem to be saying on there being none, now, allowing the life extension beyond what is normally known or possible from nutrition/exercise Summary. I....

....have now shifted to other question: Which sources give fitness programs for living longer?


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More general term than "adaptation"
The Wikipedia article about adaptation states:

Adaptation differs from flexibility, acclimatization, and learning.

What is a more general term than adaptation? For example, is there an umbrella term for adaptation and learning (and optionally other phenomena)?
Edit: Some examples of possible definitions of terms that I'm looking for:

mechanisms that change/improve fitness over time [over lifetime (learning) or generations (adaptation)] by matching the environment
how the phenotype changes [over lifetime (learning) or over generations (adaptation)] to match the environment
properties of anything that is alive that change [for example in the gene pool (adaptation) or in the brain (learning)] to improve chances of survival

Do you want a word in English or scientific/biological terminology? If the former, adaptation is fine. If the latter, I see little biological reason to group those terms since they are fundamentally different, and in the right context 'adapt'/'adaptation' can be applied to the other concepts: the article you link is only talking about adaptation as an evolutionary term (as is clear in the Wiki heading) - Wikipedia notes these other scientific uses also at https://en.wikipedia.org/wiki/Adaptation_(disambiguation)

@BryanKrause I'm looking for a word that is scientific/biological terminology or at least wouldn't contradict scientific/biological terminology. The umbrella term can for example have the meaning "properties of a population that change [for example in the gene pool (adaptation) or in the brain (learning)] to improve chances of survival".

Adaptation would be the term for changes in the population. Flexibility, acclimatization, and learning are all ways that individuals change.

@root It is a good question +1. That being said asking for an umbrella term for adaptation and learning is a bit like asking for an umbrella term for airplane and candy bar. I am going a little extreme but the point is there is not much interest for having a term for these two very different concepts. You can maybe go by with something like "how well the phenotype match the environment" or why not maybe just use the concept of "fitness".

@BryanKrause A population consists of individuals. Flexibility, acclimatization, and learning affect individuals, so they affect the population. That's what I meant. If you prefer: "properties of anything that is alive that change [for example in the gene pool (adaptation) or in the brain (learning)] to improve chances of survival". Or see my next comment.

@Remi.b I mean "how the phenotype changes [over lifetime (learning) or over generations (adaptation)] to match the environment". Or "mechanisms that change/improve fitness over time [over lifetime (learning) or generations (adaptation)] by matching the environment". (If changes acquired by learning are considered part of phenotype and fitness.) Question edited accordingly.

Adjustment = a small alteration or movement made to achieve a desired fit, appearance, or result; the process of adapting or becoming used to a new situation (Google Dictionary).
Adjustment is a very general term; it doesn't mean anything specific in biology or other sciences and it can cover all the terms you've mentioned: adaptation, acclimatization and even learning.
If you check in Thesaurus.com, you can see that synonyms for adjustment include acclimation, acclimatization, modification and improvement, and that one of the synonyms for adaptation is adjustment.

Factors or variable
Variable is probably your best bet, since it literally can cover anything that varies or can vary.
Factors can also be used but has specific meaning when dealing with experimental design so it may not be as good, on the other hand it is used less outside that so if you preface its usage with a description it is less likely to get confusing.


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Does an increased reproduction/mortality rate provide an evolutionary advantage?
If a species has a high mortality/birth rate, then it is able to adapt to changing environments more quickly than species that live for a long time.
Without a high mortality rate, food and other natural resources are hogged by previous generations and the gene pool is polluted when less evolved, older animals reproduce.
Because of this, wouldn't it make sense to conclude that a high mortality/birth rate is better for a species as a whole?
This advantage could snowball out of control, because faster evolution would lead to superior reproduction methods which would lead to faster evolution etc...
If this is true, then why are mice not more successful and adapted to their environment?

House mice were chosen because of their high birth and mortality rates.
Birth rate:
"Approximately 6 mice can multiply into more than 60 mice in 3 months."
http://www.crittercatchersinc.com/critters/Mice/Mousereproduction.html
Lifespan: 1 year
http://themysteriousworld.com/top-10-shortest-living-animals-in-the-world/
One of the reasons these traits may be more harmful than helpful is that predators benefit from a population increase. I managed to find this article in my research:
http://www.ncbi.nlm.nih.gov/pubmed/12675374
Feel free to include this source in your answer if I have interpreted it correctly. The reason I am posting this question answerless is because I am not sure enough about the conclusions I have drawn to answer it on my own and (mostly this) because I am very interested to see what other disadvantages this evolutionary strategy would have.

The first part of the question is interesting.

Does an increased reproduction/mortality rate provide an evolutionary advantage?

The concept of evolutionary advantage for a species needs to be used with much cautious as different definition of evolutionary advantage may exist. You should typically have a look at game theory beforehand to understand the issue of definition.
A species that have shorter generation time tend to respond faster to new selection pressure (even more so in species that have short generation time and also have high population size).

why has humanity not been enslaved by mouse¹ overlords with superior intelligence and adaptations to suit the environment perfectly?

You seem to be viewing intelligence and/or species competitive ability as end goal of natural selection which suggests important misunderstanding of how evolution works.

One of the reasons these traits may be more harmful than helpful is that predators benefit from a population increase

You might want to have a look at the post What prevents predator overpopulation?

"You seem to be viewing intelligence and/or species competitive ability as end goal of natural selection which suggests important misunderstanding of how evolution works."                                                                                It was a joke, but since it is detracting from the quality of the question I will remove it. Sorry about that.

1) Reproduction is metabolically costly, so a high reproduction rate, such as that seen in fishes that lay thousands of eggs at a pop, is generally a strategy to compensate for a high mortality rate. On the other hand, bacteria, that can in some cases double every 20 minutes, have the advantage of rapidly evolving resistance to antimicrobial agents.
2) Primates and elephants are examples of successful species that have a very low birth rate. The biological investment here is in nurturing and protecting offspring for many years to reduce mortality and to transfer cultural knowledge to the next generation to improve reproductive success and community success. In the case of humans, long lifespan, even beyond reproductive age, is an advantage because the older generations can help care for children while the parents work, and they support the community through leadership and by imparting to younger generations a lifetime of cultural knowledge. Unfortunately, the very success of humans may lead to its ultimate downfall, due to overpopulation and environmental degradation.
3) Mice are successful because they eat our crumbs and our crops, and take refuge in our shelters. So, in a sense they have enslaved us: we work for them without pay or benefits.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3353347/
https://frontiersinzoology.biomedcentral.com/articles/10.1186/s12983-014-0054-0
http://www.cell.com/trends/ecology-evolution/fulltext/S0169-5347(15)00104-4
https://en.wikipedia.org/wiki/Grandmother_hypothesis
https://en.wikipedia.org/wiki/House_mouse

Please add some citations in your answer, lest it is likely to be downvoted and removed.


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regarding genetic disorders related to protein production
I am not completely familiar with biology, but i had a genetics course in college along with practicals. Forgive me if there is something wrong with my question.
Is there a genetic disease which results in partially functioning or complete non functioning of genes resulting in little or no production of protein for eg Muscular dystrophy.
so why can't we supply these protein from outside the way we do in the case of diabetes(insulin)?

There are many protein deficiency issues caused by genetic mutation for eg: Protein C whose deficiency causes abnormal blood clots. This protein is controlled by the PROC gene whose mutation causes Type I Protein C deficiency (reference).
There are treatments of replacing proteins like in the case of Protein C deficiency, protein C concentrates are used (reference). In the case of Alpha-1-antitrypsin (AAT) deficiency, augmentation is done with weekly intravenous infusion of the AAT protein (reference).
So in many cases protein is actually supplied from outside the body and also many protein deficiency conditions can actually be controlled with balanced diets (reference) which unfortunately is not a solution for insulin deficiency.

thanks but what is the problem in case of say muscular dystrophy where patient is almost rendered with no cure or improvement at all?

You can fairly easily substitute peptides (short proteins) from the outside of the body, but you have to supply them by injection. They don't survive the low pH of the stomach unless you encapsulate them into an acid-resistant matrix. Short peptides are often very local and short acting, present only during specific times of the embryonic development (for example, morphokines). However, assuming that you have a peptide hormone like insulin, you can administer it systemically and it will work. There is however over 350 peptides/short protein that are extracellular and many of them are locally restricted. So, you should not just inject them. The problem with larger proteins is, that they do not cross the cell barrier like these small peptides (which have a receptor for crossing/uptake). Many of the broken genes carriers (patients) of genetic diseases have in their genome, are coding for large intracellular proteins, often even tissue-specifically expressed. You cannot get them easily to the right destination, nor can you get them easily into the cell. You have to use a virus that encodes them and infects the cell. Read some Cell / Molecular Biology textbook if you want to learn more details.


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Cellulose - why is it fibrous and not granular?

I was reading a book where it said that the 1 - 4 Glycosidic bond of the Beta Glucose meant that cellulose is fibrous and not granular.
First, what does it mean to be granular and why is not granular unlike Amylose?
Thanks, Dave.

Ive been wrong several times before so take my word with a a heavy "grain" of salt. (pun get it? :D )    But Cellulose is a linear polymer and therefore makes a fiber. I guess the linear in this case implies fiber.   Amylose has a helical structure to it i think. Here is an image i found that shows the difference. http://3.bp.blogspot.com/-WpoQllkgT3M/Ug51lW5oEPI/AAAAAAAACCI/vuJmfjHCk0Q/s1600/3starchcellulose.gif

@RoSiv Thanks a million! Please respond with your answer so I can mark you up and tick you! Good pun too!

Cool I got something right :D
Cellulose is a linear polymer and therefore makes a fiber. I guess the linear in this case implies fiber. Amylose has a helical structure to it i think. Here is an image I found that shows the difference.


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First RNA polymerase-mRNA
We know that RNA polymerase produces mRNA by reading DNA strand. Which enzyme produces the first RNA polymerase if other RNA polymerases are synthesized in the same way like other enzymes(proteins) ?

Fantastic question :D I look forward to an answer! I've thought about this a lot myself, shame I never found an answer...

it is a chicken-egg sort of question. You can have a look at self replicating ribozymes.

Contemporary cells have RNA pols from the start. If you're asking how RNA pols might have come to be, look no further than RNA-directed RNA pols.

@5heikki Would be great if you could elaborate and put it up as an answer.

not an expert, but i can hypothesize that the sperm or/and the ovule already have some RNA polymerase, and all cells keep somewhat stable this, if you mean how it happened the first time in evolution I dunno. btw cool question

@The Last Wort. I agree. Are the maternal like the mitochondriae, cp. Katz's comment.

The RNA world hypothesis states that self-replicating RNA (that is, an autocatalytic RNA polymerase) was the first form or precursor of life. So, in that context, your question is basically asking how life originated. The obvious answer is that we don't know (currently anyways), but I'm going to take this opportunity to describe a few really neat experiments which might give you some insight over a possibly contributing mechanism of how self-replicating molecules may have developed. I won't go over the Miller-Urey or Oró experiments, but let's assume that the early Earth contained organic molecules (especially nucleotides for our purposes). It's also important to keep in mind the immense time scales over which these processes occurred (the Earth is ~4.5 billion years old).
Anyways, let's talk about in vitro evolution, also known as systematic evolution of ligands by exponential enrichment (SELEX). SELEX is a procedure whereby an initial library of random RNA sequences (flanked by known sequences to be used as primer sites) undergoes a selective process followed by amplification and mutation of the selected molecules. This is repeated several times. As an example, this process can be used to create aptamers, which are small RNA molecules which bind a specific ligand. A pool of random RNA is passed over a column containing the immobilized ligand. By chance, some RNA will have some amount of affinity to the ligand. Poorly bound RNA is washed off non-stringently and then slightly better bound RNA is eluted. This RNA is reverse transcribed and amplified by PCR. The PCR primers contain the T7 RNAP promoter which allows transcription of the cDNA to produce a new  RNA pool. Somewhere in this regeneration process, mutations are introduced so that the new pool contains randomly modified copies of the RNA which had some affinity. Through repeated steps of increasing stringency, an aptamer with high affinity can be developed.

(Ellington, 1994); Outline of the SELEX process.

So how does this apply to the origin of the first RNA polymerase? It just so happens that Bartel and Szostak (1993) used in vitro selection to produce a ribozyme (a catalytic RNA molecule). This ribozyme was a ligase, that is it catalyzed the formation of a phosphodiester bond between two RNA molecules that are aligned on a template.

(Bartel and Szostak, 1993); Methodology of the selection used to generate a ribozyme ligase.

While the ribozyme created was not autocatalytic, the experiment had implications on the origin of self-replicating RNA and life in general, which were discussed in the paper:

The ribozymes that we have isolated from a pool of random sequences catalyze a chemical transformation similar to that catalyzed by polymerases. Their abundance in the random-sequence pool is therefore relevant to the hypothesis that life began with an RNA replicase that originated from prebiotically synthesized random-sequence RNA. We detected about 65 sequences (Fig. 8, pools 3 and 4) capable of carrying out a particular ligation reaction in a pool of more than $10^{15}$ initial sequences, or a frequency of occurrence of one in about $2*10^{13}$ sequences.
[...]
Presumably, sequences capable of acting as efficient template-directed RNA polymerases are more rare than this, and sequences capable of acting as an RNA replicase are even more rare. Evidently, catalysts of moderate activity could arise spontaneously from relatively small quantities of RNA (and perhaps related polynucleotides); however, a catalyst with the activity, accuracy, and dual functionality (enzyme and template) of an RNA replicase would be so rare that it could only arise spontaneously and in a single step from a truly enormous amount of RNA. The problem is compounded because two such sequences would be required for autocatalytic replication to begin, one to act as the polymerase and a second to act as the template. Therefore, an RNA replicase could only have arisen from primordial sequence pools that were not truly random. Joyce and Orgel anticipate this difficulty and propose that nonenzymatic, template-copying reactions may have had a dual role in generating primordial sequence pools that are more likely to give rise to a replicase (21). The initial pool may have been biased in favor of local secondary structure by a mechanism involving intermittent use of intramolecular sequence as the template. In addition, some sort of nonenzymatic catalysis was probably necessary for the initial copying of the replicase sequence to generate a molecule that could be used as a template, the copying of which by the replicase would generate more replicase molecules, thus initiating the autocatalytic explosion of life.
[...]
The ribozymes that we have selected provide a new starting point for the evolution or design of RNAs with RNA polymerase and replicase activity. A series of issues including sequence-independent primer-template binding, the use of mononucleotide triphosphates as substrates, fidelity, and product-template dissociation now need to be addressed before an RNA replicase activity, an activity that has probably been extinct for over 3 billion years, can be fully resuscitated.

Johnston et al. (2001) took this experiment even further: starting with a pool of slightly mutated ribozyme ligases developed in a previous SELEX experiment, they were able to generate a ribozyme polymerase. This polymerase was able to catalyze the addition of nucleotides to a growing oligonucleotide chain up to 14 bases long and based off of an RNA template. The polymerase was also quite accurate.

(Johnston et al., 2001); Excerpts from the in vitro evolution of a ribozyme polymerase.

However, the authors are skeptical of this being the sole mechanism behind the rise of an autocatalytic ribozyme:

How could general polymerase activity have arisen on early Earth? If emergence of the first RNA replicase ribozyme coincided with the origin of life, it would have had to arise in a single step from prebiotically synthesized RNA, without the benefit of Darwinian evolution. Our shortest construct retaining activity was 165 nt, with about 90 nt involved in important Watson-Crick pairing and at least another 30 critical nucleotides (23). Ribozymes with the efficiency, accuracy, and other attributes of an RNA replicase might have to be even larger than this. However, current understanding of prebiotic chemistry argues against the emergence of meaningful amounts of RNA molecules even a tenth this length (1). This difficulty is anticipated by those who propose that life, and Darwinian evolution, began before RNA. Some speculate that in this "pre-RNA world," life was based on an RNA-like polymer, yet to be identified, that possessed the catalytic and templating features of RNA but also a more plausible prebiotic synthesis (1). The pre-RNA life forms presumably later developed the ability to synthesize RNA, facilitating the emergence of an RNA replicase ribozyme, which in turn enabled the transition to the RNA world.

There are other, similar experiments where people have made self-replicating ligases (Paul and Joyce, 2002) or a system of two, cross replicating ribozymes (Lincoln and Joyce, 2009). While the question still remains unanswered, perhaps from all of this you can get a sense of the plausibility.
References:

Bartel DP, Szostak JW. 1993. Isolation of New Ribozymes from a Large Pool of Random Sequences. Science. 261(5127):1411-1418.
Ellington AD. 1994. Aptamers achieve the desired recognition. Curr Biol. 4(5):427-429.
Johnston WK, Unrau PJ, Lawrence MS, Glasner MR, Bartel DP. 2001. RNA-Catalyzed RNA Polymerization: Accurate and General RNA-Templated Primer Extension. Science. 292(5520):1319-1325.
Lincoln TA, Joyce GF. 2009. Self-Sustained Replication of an RNA Enzyme. Science. 323(5918):1229-1232.
Paul N, Joyce GF. 2002. A self-replicating ligase ribozyme. P Natl Acad Sci USA. 99(20):12733-12740


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Are bananas C3, C4, or CAM plants?
Are bananas C3, C4, or CAM plants? I have been researching for some time and cannot find the answer.

First of all, we have to think about the ecosystem in which banana exist. Obviously, the banana is in a rain forest. Rain forests are a very interesting ecosystem with lots of species. The climate is really hot and the atmosphere has high humidity.

Banana is definitely not CAM plant, because this kind of photosynthesis has usually cactuses and succulents. CAM plants usually have closed stromas during the day and open at night to protect from possible loss of water, carbon dioxide. This type of photosynthesis doesn't suite into the rain forest.

C4 plants are well known for Kranz anatomy of a leaf. They have special sheets to do secondary fixation of carbon dioxide. So according to this web I personally believe that banana is not C4 plant.

So according to this article the banana has C3 photosynthesis.

Anyway according to wiki there is a lots of cultivars and specious of bananas so i really dont know if its true for all of them.

The PDF you linked to is broken. You may want to link to the original article page instead of the PDF itself.

You can find a list of families known to have C4 plants here. [based on Sage 2016]1.
Although many other monocot species do exhibit C4 photosynthesis (and C4 photosynthsis does seem to have evolved independently multiple times)2, the banana family, Musaceae, consists of C3 plants3.
This includes the most commonly consumed variety of banana in developed countries, the Cavendish banana.

Sources:

Sage, R. F. (2016). Journal of Experimental Botany 67(14):4039–4056
Ehleringer et al (1997). Oecologia 112:285299.
Biocylopedia