texts: Can Chilopoda "vocalize" or produce sound for the express purpose of communication, as opposed to sound as a byproduct of other movements?

texts:
Is there any species of Chilopoda that can "vocalize" or or otherwise produce sound for the express purpose of communication, as opposed to sounds it might create  as a byproduct of other movements and body functions?

An example of non-communication sound in other arthropods would be insects wings causing "buzz" sounds while in flight.

An example of a communication sound in other arthropods would be crickets (and others) rubbing their legs together to "chirp".

Do any Chilopoda intentionally create sound for the purpose of communication?


texts: Size of the glycan chain in a glycosylated protein

texts: I would like to know where I can find the (experimental/estimated) distribution of glycan sizes attached to proteins.


texts: Land Shrimp Sighting (Western Europe): What is it?

texts:
This approx. 6cm long insect was moving rapidly across the asphalt in a wavy/jumpy motion. It makes me think of a shrimp. It has a kind of widened head like a hammerhead shark.

I got two shots with my smartphone camera. Not the best quality.

What is it?

Position: Western Europe
Season: Start of Summer (June 20)
Time of day: Mid-morning
Location: Next to a largish marsh area currently kept as mini natural reserve in the middle of agricultural fields after large-area
school buildings got dropped on the landscape. Sadly this area is
likely to be marred by additional construction soon, the money is
just too good and attracts sharks and brown envelopes.


texts: I just studied Biological Nitrogen Fixation and saw it's reaction but i do not understand why there is 8 electrons and 8 protons are involved and Hydrogen molecule is formed side by side along with 2xAmmonia... According to me there should be 6electrons and protons because it needs 2electons in each step from Nitrogen to Di-imide and 2electrons from Di-imide to Hydrazine to give out 2xAmmonia


texts: Could removing non-functional parts of coenzymes improve enzyme function?

texts: As pointed out here, many important co-enzymes (essential enzyme cofactors) such such acetyl-CoA and vitamin B12 contain nucleotide portions that do not function in the enzyme catalysis. They have been suggested to be relics of the RNA world, so it would appear to me that they are redundant. Suppose we were to remove these nucleotide portions of the co-enzymes, would that improve the working of the proteins (and perhaps our health) or wouldn’t it make any difference?


texts:
Some sources say that gametes are haploid, some say that they are diploid.

I'm confused.


texts: Deducing synaptic strength from electron micrographs?

texts:
There are several promising techniques for connectomics based on iterative sectioning and imaging of tissue with scanning electron microscopes (e.g. FIB-SEM and ATUM)

By looking at such micrographs, one can identify synapses:

Is there any way to measure synaptic strength using these types of techniques?


texts: Are there any photosynthetic catalysts in use other than chlorophyll?

texts:
When I search for catalysts other than chlorophyll on Google, I only get references to artificial photosynthesis. When I look up photosynthesis, I see accessory pigments mentioned, but it appears that the chlorophyll family is crucial.

These chlorophyll variants all have the chlorin (not to be confused with chlorine) ring in common.

Are there any photosynthetic organisms that do not use a chlorin derivative? Why is chlorin so predominant?


texts: Accurate Human Skull Model for Educational Purpose

texts:
I want to buy a model of Human skull for education purpose. However, I really want a very accurate model and at a decent price. I got the info that many of the available skulls in the market are not accurate.  Can anyone suggest me one?

Also I want to know is there any regulatory body that certifies such
educational models regarding the accuracy etc.? If not then what is the way I can ensure that I am buying an accurate (or most accurate) model.


texts: How much arteries expand during systole?

texts:
Arteries expand during systole. By what percentage, on an average, does the arteries' diameter change during systole  with respect to diastole? Answer may depend upon type of artery i.e. elastic artery,  muscular artery, arterioles etc, you may specify the type.

This
https://www.google.co.in/url?sa=t&source=web&rct=j&url=https://www.nature.com/articles/eye199419.pdf%3Forigin%3Dppub&ved=2ahUKEwjuy4_Z2rvaAhWMYo8KHXuVAfcQFjAFegQIARAB&usg=AOvVaw3L27QesaUFNIqGfkINgy-7
paper shows 3-4% change in diameter of retinal arteries, but size of the arteries is roughly 100 microns. I am more interested in arteries with diameter more than 1 mm.


texts: Is there a known glucosepane cross-link breaker?

texts:
I read the following on wikipedia:

  There is, however, no agent known that can break down the most common
  AGE, glucosepane, which appears 10 to 1,000 times more common in human
  tissue than any other cross-linking AGE.

(AGEs are related to oxidative stress, aging and chronic diseases.)

I was wondering maybe the article is out of date, and there is a glucosepane cross-link breaker available. Do you know anything of that, or a current research which aims to find that?


texts: Avoid Blood lyse color remain in DNA extraction

texts: I tryed several times to extract DNA from freezed blood sample whit Qiagene kit but it gave very small amount of product due to good purity then I try extract manually by using CTAB PVP method and finaly gain a much more DNA but the lysate color in sample remain in DNA pellet an do not disolve in any solvent to seperation I tried to add small amount of accorbic acid but just the color get reduce to red from gray:'( . If every one have a idea which can help me please gave in a small answer.


texts: Oxygen uptake with gills from water vs lungs from atmosphere

texts: The concentration of oxygen in water tends to be around 6.5-8 mg/L. In the atmosphere, it is 21%, one liter of air weighs roughly 1.25 gram, so, oxygen concentration is 0.25 g/L or 250 mg/L. So, lungs can access 50x higher concentration of oxygen than gills can. This suggests, sort of, that maximum oxygen uptake possible should have a significant increase when lungs evolved. Is that trend observed and a topic that is often talked about?


texts: Two mice heterozygote and black are reproduced. Find the probability of getting the filium dark and heterozygote

texts:
Well, here's what I did: P: Aa*Aa

F1: 1/4 AA, 1/2 Aa, 1/4 aa, SO the answer is 1/2, but out teacher did this:
AA(1)    Aa(2)    aa(1) and she said we divide the number of filium for the phenotypes number and get 2/3. This is the probability. I don't get it.


texts: Can a Chihuahua and a Great Dane breed the "old fashioned way?"

texts:
I saw this vid:

https://youtu.be/eu2qe-FNtjg

And this question crossed my mind.  The dog in the video seems to be boxer sized... And I wonder if that strategy would work with something a little bigger....
Also, this is obvious, but let me clarify: 'I'm thinking about  a FEMALE Great Dane and a MALE Chihuahua. (The other way arround, we would get a Chihuahuaburger before anything even happened... And would be animal cruelty. ) Since they're the same species ( a dog, aka Canis lupus familiaris) that means they can make  viable offspring, rigth?


texts:
It has become well-accepted that microbiota of the gut (a.k.a. gut bacteria) consume calories that are ingested and can have significant effects on energy metabolism in humans. For example, if you take the feces from mice that have had a gastric bypass and transplant those into the colon/GI tract of obese mice, then the obese mice lose weight (See here for article about this study).

Are there any known estimates on how many calories the typical gut microbiota in an adult human consumes? That is, about how many calories your gut microbiota use per day?

For more information there is a freely available source on Pubmed, "The Human Microbiome, Diet and Health Workshop Summary."


texts:
In early embryonic development, some female cells pass through a process called lionization and one of the X chromosomes get condensed and began to be called Barr body.

What I don't understand is how the Barr body behaves during mitosis. Specifically, if a cell had condensed a paternal X chromosome, all of its children will have a paternal Barr body. But aren't  the barrbodies supposed to decondense to be able to be copied during mitosis? If so, when they recondense, why isn't the choice of which chromosome will condense random?

Thank you!


texts: Where should I go for online information on animals endemic specifically in Mozambique?

texts:
I've been involved with the citizen science project "Wildcam Gorongosa" for over half a year now (website, forum). As there are lots of unexperienced volunteers, many questions are being asked. Often I'd like to answer, but also not having a biology background I usually have to do some research first to give an accurate answer. For this reason, I'm looking for informative, up-to-date online resources, like e.g. search engines, animal guides etc.

I have come across a few websites that give some information on animals in the whole of Africa (e.g. ultimateungulate.com) - but I wonder if there are more suitable places to go if I'm specifically looking for animals in Mozambique (or even Gorongosa National Park). I'm still relatively new to the topic - where would a scientist involved with research on Mozambican ecology go and look for this kind of "specific" information? As the project deals with pictures taken by wildlife cameras, I am only interested in animals of a certain size (I guess rat-sized and larger). I'd be happy to find e.g. more information on the appearance of each species, its geographic distribution, their respective habitats and their general behavior.

I realize that this question is somewhat broad - please do ask ahead, I'll try to add details if necessary!


texts: Why DNA needs histones to be packaged and ordered?

texts: I know that histones are proteins that package and order the DNA into structural units called nucleosomes, my question is Why DNA needs histones to be packaged and ordered ? Why DNA cannot do that by itself ?


texts: How is the gradient in density gradient centrifugation made?

texts:
From the literature I read, I came to understand the following. Please correct me if wrong.

In CsCl gradient centrifugation, the gradient is achieved by centrifuging the CsCl solution at high rpm, which causes the heavy Cs ions to distribute unevenly throughout the solution, due to sheer centrifugal force.
In Sucrose gradient, solutions of decreasing concentrations of sucrose are layered one over the other slowly.

Why can't we achieve the sucrose gradient by simply centrifuging it like in the CsCl gradient?


texts:
It's embarrassing for me to ask this but well such is life. NIMH Psychoactive Drug Screening Program (PDSP) Ki Database is mentioned as the source of the average binding affinity (Ki) values given in Goodman and Gilman but whenever I try to, in some way, confirm that these values are averages obtained from PDSP I get values that are way (up to 10,000 fold) off the values given in Goodman and Gilman. (ps. I am a mathematician too so I know how to take an average, $\bar{x} = \frac{\sum_i^n x_i}{n}$ so you don't need to hold my hand through the calculation with something as simple as the conventional definition of averages) Therefore I have reached the conclusion that I must be doing the calculations wrong. Please show me how to do them correctly. Here's a screenshot of exactly what Goodman and Gilman says that's confusing me:

Oh and yes I am using just the cloned human transporter values not just all the stuff that comes up.


texts: Is PrEP used for anything other than HIV?

texts: In the field of HIV prevention, PrEP is an abbreviation of pre-exposure prophylaxis. This is a very generic term. Are any diseases other than HIV prevented using a similar approach? Do they use the same name?


texts: How do I reverse my insert within a plasmid?

texts:
I have a plasmid with:

...T7pro. -- RBS -- XBa1 cut site -- ProDpro. -- RBS -- AmilCP -- T -- Spe1 cut site -- T...

How do I design primers to reverse the portion in bold, such that the T7 and ProD promoters are on opposite sides of AmilCP? I am finding it difficult to understand how to design the appropriate primers.


texts: Do you know any primers that can be used to genotype mice and check if they are still C57B6? I'm concerned about genetic drift in my colony. I bought a breeding pair 3 years ago and expanded. I wanna make sure my animals still retain genetic markers of c57b6. Thanks


texts: Mixed-mating plants: is the number of mixed mating plants supposed to be trivial?

texts:
I am referring to Winn et al. 2011

Last sentence of the first paragraph is

  Although sampling bias against both selfing and highly outcrossing species may inflate the frequency of mixed-mating populations, the number of species reported to show mixed mating is not trivial, and calls into question the status of mixed-mating populations as transitional, and therefore the sufficiency of the theory to explain the observed distribution of mating systems in hermaphroditic species.

I do not really understand what is the logic behind the highlighted part and what is its purpose.

Is the number of mixed mating species supposed to be trivial in a case where the number is inflated (So there is a need to clarify it is non trivial)?
How does the fact that it is not trivial bring up the question below the highlighted part?


texts: How do Rab proteins ensure specificity in vesicle transport?

texts:
From this paragraph, from Molecular Biology of the Cell 6th Edition, the author makes it quite clear that Rab proteins are important for the specificity of vesicle transport and that Rab proteins are used as molecular markers that identify compartments. They also make it clear that for many membrane fusion events active Rab proteins are required on both sides of the reaction. What is not clear to me is how Rab proteins ensure specificity?
The author is not clear on how Rab proteins ensure specificity. The only way I can imagine this happening is that Rab proteins on the target membrane recognise Rab proteins or other molecular markers on the vesicle and only bind to appropriate markers, but the author does not clearly state this in the text.

Specificity in targeting is ensured because all transport vesicles display surface markers that identify them according to their origin and type of cargo, and target membranes display complementary receptors that recognize the appropriate markers.

What 'surface markers' and 'complementary receptors' is the author talking about here? Due to the position of the sentence in the paragraph below I'm inclined to think they are talking about Rab proteins and SNAREs.

To ensure an orderly flow of vesicle traffic, transport vesicles must be highly accurate in recognizing the correct target membrane with which to fuse. Because of the diversity and crowding of membrane systems in the cytoplasm, a vesicle is likely to encounter many potential target membranes before it finds the correct one. Specificity in targeting is ensured because all transport vesicles display surface markers that identify them according to their origin and type of cargo, and target membranes display complementary receptors that recognize the appropriate markers. This crucial process occurs in two steps. First, Rab proteins and Rab effectors direct the vesicle to specific spots on the correct target membrane. Second, SNARE proteins and SNARE regulators mediate the fusion of the lipid bilayers. Rab proteins play a central part in the specificity of vesicle transport. Like the coat-recruitment GTPases discussed earlier, Rab proteins are also monomeric GTPases. With over 60 known members, the Rab subfamily is the largest of the monomeric GTPase subfamilies. Each Rab protein is associated with one or more membrane-enclosed organelles of the secretory or endocytic path- ways, and each of these organelles has at least one Rab protein on its cytosolic surface. Their highly selective distribution on these membrane systems makes Rab proteins ideal molecular markers for identifying each membrane type and guiding vesicle traffic between them. Rab proteins can function on transport vesicles, on target membranes, or both.
Like the coat-recruitment GTPases, Rab proteins cycle between a membrane and the cytosol and regulate the reversible assembly of protein complexes on the membrane. In their GDP-bound state, they are inactive and bound to another protein (Rab-GDP dissociation inhibitor, or GDI) that keeps them soluble in the cytosol; in their GTP-bound state, they are active and tightly associated with the membrane of an organelle or transport vesicle. Membrane-bound Rab-GEFs activate Rab proteins on both transport vesicle and target membranes; for some membrane fusion events, activated Rab molecules are required on both sides of the reaction.

I read this article and it states that;

For its functions, active Rab5 must be localized to both endocytic vesicles and early endosomes.

In this case I can understand how Rab proteins ensure specificity in that Rab5 on the target membrane will only interact with an endocytic vesicle if it has Rab5 on its surface. But is this always the case? Will Rabs on a membrane always require certain Rabs or other molecules on the surface of a vesicle in order to tether and dock the vesicle? If not I can't see how they are providing specificity to transport.


texts: Why is Homologous Recombination (HR) more frequent at long sequence repeats?

texts:
I'm studying plasmids in bacteria (E. coli), and trying to understand the well-cited phenomenon that recombination frequency increases with longer repetitive sequences. I think this also applies to eukaryotes.

In my (potentially misguided) current view, HR can occur between two DNA duplexes either during or after replication (?). As I imagine it, the new DNA duplex will have near identical homology to the template duplex (from which it has just been replicated), meaning that sequence homology is widespread across the entire molecule. This would mean that sufficient homology between sister chromatids can be achieved anywhere (?), negating the trend for 'long sequence repeats'.

So, why is there a focus on long repeats promoting higher recombination frequencies? Is my view on when HR happens misguided?


texts:
My kids and I are doing a fun project collecting pictures of life in parks and national parks around us. We are trying to classify what we find down to genus and species.

However, I'm confused about what the plant phyla are. With animals, it is pretty clear (e.g. arthropods, chordates), but I don't understand what they are for plants. I see informal groupings and divisions, but not what phyla.


texts: Why is the human body able to repair a broken bone and not a heart muscle?

texts:
The human body can repair skin/organ laceration, fractures, even repair nerves - albeit the duration and rate of recovery differ.

Why can the heart muscles not repair themselves?


texts: I've heard from several sources that the predominant form of alternative splicing (at least in mammals) is exon skipping. However, my personal evidence is only anecdotal: I've heard it and read it, but have not seen references to literature. Is there a seminal paper or set of papers establishing this finding that I can cite?


texts: Additive genetic variance $V_A= 2pqa^2$ ... what is $a$?

texts:
Reading Falconer and Mackay looking at equation $V_A = 2pqa^2$ (equation 8.5, page 126).

I am trying to write a clear explanation of how additive genetic variance is defined and calculated, but I keep getting twisted up in the books I am working from.

Just what is the term $a$ and how is it calculated?


texts: Why do genetic drift generates negative linkage disequilibrium?

texts:
The very first sentence of the abstract of this article is:

  "In finite populations subject to selection, genetic drift generates negative linkage disequilibrium, on average, even if selection acts independently (i.e., multiplicatively) upon all loci."

Question

Why does genetic drift generate negative linkage disequilibrium?


texts:
It is often stated that most cells in the human body have a primary cilium.

Which ones don't? For which cells is it unknown?


texts: Can different proteins be produced during translation of a single mRNA in eukaryotes?

texts: Is there a translational mechanism that eukaryotes can use to produce different proteins from a single transcribed mRNA?


texts: What is different between the pigment of giraffes and the pigment of flowers?

texts:
I saw this video created by Derek Muller and he says there that it is very unusual to evolutionary develop the colour of the skin without the pigment. That sounds reasonable but if so, what nutrients have to get animals with pigment to get colored? Is it an active job of the cells or skin cells are just full of colorful minerals?

In case of giraffes: How does skin correct the shape of the spots? (For instance in cause of zebras it is clear according to this video)

And what about purposely colorful flowers? What nutrients do they need?

Thank you very much.


texts:
Plasmid pBr322 includes two genes that confer antibiotic resistance: a gene for ampicillin and  a gene for tetracycline. The cutting site for the restriction enzyme BamH1 is in the middle pf the tetracycline resistance gene. The cutting site for the restriction enzyme Pvu1 is in the middle of the ampicillin resistance gene.

If you were using a cell culture plate that contained ampicillin, which restriction enzyme (BamH1 or Pvu1) would you use to cut the plasmid and excise the gene you wanted to insert?

Attempt:

I would assume you need to use Pvu1 since the cutting site is in the ampicillin resistance gene, but the correct answer is BamH1. Why?

Any help would be awesome! Thanks!


texts: How does sugar enter neurons if they don't use insulin?

texts:
I heard somewhere that as opposed to other cells, neurons do not use insulin to get their sugar supply.

Why is that?

What is the alternative mechanism? I assume sugar can't just enter the cell without some kind of help from a protein, is that true?


texts: Why does lactate build up prevent a further increase in the speed of an athlete?

texts:
This question was triggered by an exam question that I was doing on the following paper (Q2 part (b)(i)):
http://qualifications.pearson.com/content/dam/pdf/A%20Level/Biology/2013/Exam%20materials/6BI05_01_que_20120307.pdf
Here is the markscheme:
http://qualifications.pearson.com/content/dam/pdf/A%20Level/Biology/2013/Exam%20materials/6BI05_01_msc_20120215.pdf

I do not understand why the decrease in pH results in the lack of of increase in speed, despite hours of research. Here are my best attempts:

The build up of lactate will have to keep the power output of the muscles, as a whole, constant, rather than allowing it to continue increasing. Therefore, there must be a link between the increased acidity of the muscle cells and the limiting of the power output. Now, if the markscheme is correct and the increase in acidity causes a decrease in the ATP production, this means that the ATP concentration within the cell decreases. However, the decrease in ATP concentration should decrease the power output rather than limit it, because less myosin heads will be able to contribute to the pulling of the actin filaments during the contraction of a sarcomere. Am I correct, or is there more to this? If so, why is there a limiting of the power output of the muscles rather than a decrease in it?


texts: For an experiment I'm going to prepare an artificial seawater agar. Before use, I have to sterilize the medium of course. I imagine, that autoclaving will cause the salts in the seawater to precipitate. Can I re-suspend them afterwards, or will it irreversibly change the composition of my medium? Should I use a different sterilization method altogether, e.g. filter sterilization?


texts: Is it possible to identify this microscopic particle?

texts:
So I was playing amateur scientist with my 11 year old.

This photograph is from rainwater in a bird-feeding bowl in south England, at 300x.

It looks biological, but I have no idea what this is. Is it possible to know, beyond speculation, what this item is?


texts: How sterile is working next to a bunsen burner?

texts:
When I was still doing lab work, many people would just wear gloves and work next to a bunsen burner because the clean benches were all in use.

This was mostly for plating bacteria like Bacillus subtilis. The equipment had been autoclaved, of course, but is just having the bunsen burner next to you without working in a clean bench really enough to avoid contaminating your plates?


texts: Humans best at long distance running: purely physiological or is it a function also of ability to pace?

texts:
I have read that although certainly other land animals are much faster over short distances, a human can run down any other animal over time, so that if a human is hunting like a gazelle, etc. eventually the human will catch up. I am wondering if this is purely a physical thing or if humans, knowing how to pace themselves, avoid exhaustion while the gazelle just runs as fast as it can and then collapses -- is it possibly because humans are smarter that they are better long-distance runners? (Now, some birds are able to fly for thousands of miles and I guess also in water we can't compete.)
EDIT: I understand that humans have some physical attributes that contribute to their long-distance abilities but is the ability to understand pacing also part of it?


texts: Could there be any effects from low powered infrared being used to track eye movements long term?

texts:
Basically,  looking  into infrared LED's and a camera with an infrared bandpass filter for tracking eye movements; my concerns are whether there would be any potential negative long term effects from constantly illuminating the eye with low power infrared?
TIA
A


texts: Is it possible for human body to convert carbohydrates to protein?

texts:
Is it possible for human body to convert carbohydrates to protein to build muscle for example?

EDIT: I read in many articles that you should eat more than 1.5 gram protein for each 1 kg weight of your body to gain muscle, but I see some bodybuilders that I know they don't eat that much of protein but gain muscle and have muscular body. So it was interesting to me to ask this question here!


texts:
I'm currently researching bat social calls (not echolocation calls) and have been given a series of samples (in .wav format) and wanted to know if what I can hear is actually the social calls. Below is a Graph representation of the a sample from the data I have:

This looks fine to me. From this, I can clearly tell where the social calls are. If I play at the specific peaks, then it sounds like a bat "chirping." However, I've been told that social calls cannot be played back, and, therefore humans cannot hear them. I'm just trying to figure out what these noises, or, chirps might actually be.

Here is a link to the .wav file:

Thanks for your help :)


texts:
I've understood that a virus is not a living organism (like e.g. a bacterium). From Wikipedia I get that a poison is a substance that reacts physically or chemically with molecules in the human body. Since a virus is a protein that binds to certain cells in the body and alters the cell's function in a harmful way (resulting in the production of more viral matter), why is a virus not a type of poison? (Or is it?)
Additional info:
I'd like to understand the difference between them—if any—on a chemical and physical level, as well as the consequences for treatment. For example: we all know by now that viruses can only remain harmful/intact on surfaces for a certain amount of time. However, I would think that a poison on a surface does not have such a time limit (but I may very well be wrong). What's the difference, if there is one? Why is licking a banister with viral load older than 4 (or so) days not harmful, but is licking a banister with poison older than 4 days?


texts: Why is the Red Fox colored bright orange?

texts: They're not poisonous or anything, so it can't be aposematism.  As far as I know it doesn't come from diet like the flamingo.  They're not apex predators, so they can't get away with it (like tigers), and honestly it seems like a big risk factor given how many species prey upon them.  As well as something that would make hunting more difficult for them.  I understand they prefer dense brush, and I think hunting during low light hours, but orange against green is about as starkly contrasting as it gets.  So does that just leave sexual selection?  One of their sexes thinks it's pretty, basically?  Or is there some other reason for it, one that might have something to do with the rest of the odd coloring?


texts: Why Cerebrospinal fluid is not heated for VDRL?

texts:
For performing VDRL of serum , we heat serum to inactivate complement proteins which may otherwise interfere , but why don't we do same for CSF even though it too has complement proteins in it?

Is it because of lesser stability of WBCs in CSF( which is hypotonic) and on heating may rupture to release cardiolipin? But I can't comprehend how its worse than having complement proteins?


texts: Is sexual selection evolutionarily advantageous?

texts: Our biology teacher says that peacocks will soon become extinct because of bigger and bigger (and heavier and heavier) tails. Why natural selection did not eliminate sexual selection?


texts: Interpreting graph of mitosis and meiosis

texts:
Note : Consider the y axis as 1,2,3,4(not 2,3,4) and x axis as time. Roman numerals should be considered from I-X ( some are not correct here )

Which stages show mitosis?
My answer : III-V

Which stages show meiosis?
My answer : VII-X

Am I right ?


texts: Natural rulers: What organisms have the most regular size?

texts:
What organisms exhibit the most precise length scales?  E.g. are there trees with rings that are of very precise thickness, or single celled organisms which are all very nearly the same length?

In particular, it seems to me that most lengths in nature are precise only to about the 10% level.  Are there any organisms which exhibit length scales considerably more precise than this?

(Bonus points if you can tell me the most precise mass scales in nature, too.)

PS: This question is partially motivated by ongoing studies by physicists as to the origin of length scales in biology.  See this paper for an example.


texts: Primitive streak being only present in caudal half of embryo affecting gastrulation?

texts: It is my understanding that in gastrulation epiblast cells migrate to the primitive streak where they start to form the three germ layers; does this mean that gastrulation only occurs at the caudal half of the developing embryo


texts:
I found this spider in my flat in Berlin, Germany. It looks like a Cheiracanthium, but which species? Mildei? Or is it a different spider?

The body is approx. 8-9mm long and it lost 4 legs when I tried to catch it unfortunately.


texts: Can drinking caffeine, alcohol and other diuretics be part of a good drinking regime?

texts:
Tea, Coffee, Beer, Coke etc…

I wonder if the benefit from amount of fluid we get from them is bigger or smaller then the handicap of dehydration. In other words it is worth to drink them if we want to have a good drinking regime?

Opening on the recommendation from this question.


texts: How are chromosomes counted at the end of mitosis in a plant cell?

texts:
Page 89 of the Study Guide for Campbell Biology, 11th Edition has the following question:

  A plant cell has 12 chromosomes at the end of mitosis. How many chromosomes would it have in the G2 phase of its next cell cycle?

  a. 6

  b. 12

  c. 24

  d. 48

Page 449 states that the answer is b.

As far as I understand, the number of chromosomes a cell has in G2 phase is double the number of chromosomes as it has after mitosis (which would imply the answer is c).

For (b) to be true, the plant cell must have had 6 chromosomes at the end of mitosis, but the question states it had 12. The only way I can imagine this to be true is that the question assumes that "a plant cell [...] at the end of mitosis" represents both daughter plant cells before the cell plate & cell wall has fully split the two daughter cells up, but doesn't "the end of mitosis" imply that the cell wall has completely formed and there are two cells (each with 12 chromosomes)?


texts: What is the fastest way to crystallise lysozyme (for student course)?

texts:
High school sudents are going to visit my university and I plan to demonstrate crystallisation of lysozyme. I ordered pure lysozyme from VWR. I can easily crystallise this within 15 min in batch (4% w/v NaCl, 35 mg/mL Lysozyme dissolved in 0.2M NaAc). However, as many different student groups will go through this experiment sequentially, it is preferable that it takes even less time (5 min waiting time maximum). I can of course try to optimise this on my own, but I am wondering if anyone has experience with the absolute fastest way lysozyme forms crystals in a batch setup (to save time and chemicals).

In summary: What are the most optimal buffer/pH/lysozyme concentrations that will give crystals (in a batch experiment) within a very short timeframe (<5-6 min)?


texts: Can the movement of water in plant outside xylem be multidirectional ,like in case of sucrose transport?


texts: Why might long telomeres be selected for in laboratory mice?

texts:
In a recent episode of The Portal, Eric Weinstein sits down with his brother Bret Weinstein to discuss Bret's Reserve-Capacity Hypothesis. It's an incredible story of scientific discovery and and academic injustice.
One prediction of the hypothesis was that laboratory mice, known at the time to have abnormally long telomeres for their lifespan, were not a representative sample of the wild mouse population because the environment the lab mice were being bred in was selecting for longer telomeres. This had serious implications for drug safety testing.
My surface level understanding as a non-biologist from listening to the Podcast goes like this. Please point out any misunderstandings.
Antagonistic Pleiotropy Hypothesis for Senescence
George Williams predicted that pleiotropic (multi-purpose) genes which are advantageous early in life but detrimental later in life will be selected for in nature since organisms often die or reproduce long before the disadvantageous effects manifest themselves. This is an evolutionary theory for aging, which argues that trade-offs exist between early life and later life fitness. This effect was observed, but no gene had been known to be the cause. This was the "missing pleiotropy".
The Hayflick Limit
Telomeres are repeating, non-coding regions of DNA at the end of each chromosome which aid in cell division. Each division, the telomeres shorten. Telomeres are counters of sorts, which provide a hard limit (the Hayflick limit) to the number of divisions a cell can undergo. Any cell that started dividing uncontrollably (cancer) would eventually reach its Hayflick limit and die. Aging (senescence) is the manifestation of cells in an organism reaching their Hayflick limit.
The Reserve-Capacity Hypothesis
This is Bret Weinstein's work. The way I understand it is that Weinstein pointed out that the missing plyotropy was not a gene at all, but telomeres. Weinstein observed that there existed a trade-off which was reflected in telomere length. Long telomeres allow cells to repair themselves many more times, slowing the effects of aging, but simultaneously leave the organism vulnerable to cancer, as cells which begin to divide uncontrollably will never reach their Hayflick limit. The length of telomeres is the result of a trade-off between dying of cancer, or dying of old age.
The JAX Lab Scandal
One critical prediction of the Reserve-Capacity Hypothesis was that mice (which were at the time thought to have abnormally long telomeres for their lifespan) don't naturally have long telomeres. Instead, it was specifically the mice coming from the Jackson (JAX) Laboratory (which supplied a significant percentage of North America with mice) which had abnormally long telomeres. Since JAX Lab had economic incentive to breed as many mice as possible as quickly as possible, they were artificially introducing selective pressures on the mice. Namely, the pressure of breeding the mice early in their lives. This meant that any late-life disadvantages, such as susceptibility to cancer as a result of longer telomeres, were not playing an important role since the mice were bred well-before they were likely to develop cancer. Since telomeres are a non-coding region of the chromosome, variation can happen very rapidly (no need for the traditional timescales of Darwinian selection). Over time, long telomeres became dominant in the mice population, and so research being done on mice purchased from JAX lab concluded that mice had very long telomeres.
The primary gap in my understanding is the following. Why was it that longer telomeres were selected for? It is unclear to me how discounting the late-life disadvantages of long telomeres would result in long telomeres becoming dominant in population. If anything, telomere length should become irrelevant. If so, we'd see a wide distribution of telomere length. That is, unless longer telomeres provide benefits to organisms early in life. Is that the case? If not, how can we explain long telomeres becoming not just common, but dominant?


texts: Plants has the capacity to take in both CO2 and oxygen, that's during day CO2 and at night oxygen. Why don't humans have such a capability?


texts: Are there differences in energy of glucose isomers?

texts:
There are many isomers of glucose, including galactose and fructose. Do they have different chemical energy levels, and why? What makes galactose and fructose useful compared to glucose, and would they be more or less energy efficient at storing energy?

Basically, can isomers have more or less chemical energy than others?


texts: Is it true that bees and wasps don't sting if struck by hand while they are in flight?

texts: Is it true that wasps don't sting if struck by hand while flying? I know of one person who claims to have done this at least 20 times and has never been stung. And out of curiosity (not that I'd want to kill them), what about bees?


texts: Why Goldman Equation cannot be used to calculate dynamic changes of membrane potential

texts:
I'm reading about Goldman Equation and I've seen in some resources that it calculates the resting potential (not membrane potential in general) and that this equation cannot be used when membrane potential is changing. One example is in Kandel textbook:

  This equation applies only when Vm is not changing. Principles of Neural Science. Eric Kandel, Fifth edition. p. 135.

I don't really understand why this equation cannot apply when Vm is changing. Precisely, I understand that this equation defines how membrane potential changes taking into account permeability and concentration of ions. If you "give" to it the concentration-permeability changes for each moment, it'll show the Vm for each of these moments.

Could someone explain that to me?
Thank you very much!


texts: Ways to monitor enzyme kinetics with very fast time resolution?

texts:
I'm interested in any way to do time-resolved study of enzyme kinetics.  I am studying some physical variables that may affect kinetics, but I want to study how quickly they take effect, and how long the effect lasts.  The time scale of interest is milliseconds or less, so the typical spectrophotometric methods (which usually look at absorption change over fairly long times on the order of minutes) won't work.

Luciferase activity can be monitored by tracking the light emitted, and this has potentially very high time resolution as the time between reaction and light emission is on the order of microseconds.  However luciferase is a bit of an odd model, as it is not part of normal metabolism or signalling in most organisms.

Is there a way to track enzyme kinetics of any other enzymes with a similarly fast time resolution?

EDIT Just discovered one name for what I'm looking for: "transient kinetics".


texts: Career advice for a bachelor of biology with russian STEM diploma

texts:
I'm from Russia. I majored in biology(genetics), wrote a bachelor's diploma in the field of psychogenetics, and graduated with mean grade of roughly 4 out of 5. Back then some circumstances arose that prevented me from an academic career (including lack of biotech companies in my area), so I had to make do with an entry-level job. Biotech companies in Russia can afford to be picky and hire only experienced staff even for an entry-level position such as lab technicians. With a lot of people in the field looking for a job, and a few biotech companies, I don't have a lot of chances there.

I've heard that Russian diplomas in STEM fields are valued abroad, probably more than they are in Russia; that brings me here. What are my chances of finding positions as a junior lab member, lab technician, etc. in a biology-related field overseas with my higher education diploma and practical experience (achieved during two years of lab work in the university)? What skills/qualifications do I need to get to improve my chances? What direction would you suggest to start my research on possible employers? Could you give me any further tips on career track?


texts:
I have some FASTQ files in two datasets which are sequences from 16Srna region. The first dataset is amplicons form V4 region and the second is V3-V4 region.

However all the reads are 250 nucleotides long, whereas one region is strictly included in the other. So what is the biological meaning of the length?

I'm expecting reads to have the same length as the sequenced/amplified region. I don't know the size of the regions but one is obviously longer than the other.

Thank you
(I thought it was better to ask here rather than on bioinformatics.stackexchange.com)


texts: How do bulliform cells cause a leaf to fold in half when the leaf looses water? Also, how would these bulliform cells be arranged to cause the cell to instead curl up?


texts: How much variation is there between DNA molecules from the same organism

texts: If different but in tact molecules of DNA were extracted from my body, for example hair sample, blood sample, and mouth swab, how much variation would there be between DNA molecules?


texts: Which gene regulatory network is the largest in human?

texts: What is the maximum number of nodes involved in any gene regulatory network and which network is it, provided its from human?


texts: Since Darwinian times, has there been any striking/notable effects of evolution on humans?

texts:
I understand that evolution is constant process that acts on a population in successive generations. Thus, it is obvious that evolution is happening. However, I'm curious as to the  stricking examples of evolution that have occurred since Darwin's publication of the theory.

Essentially, how different are we now from the humans at the time at which evolution was conceived?


texts: Is it normal for corn to have multiple ears in one place?

texts: I have (out of a mistake) one corn plant in my greenhouse and it made 4 cobs in one place. Is that normal?! I never saw something like this before.


texts: Nutritious protein substance for vitamin enhanced crop?

texts:
I am not a bio or science major, but we have a subject, like an elective on biotechnology and we were tasked to think of a product that hasn't been invented yet. My groupmates and I thought of a vitamin enhanced crop to help fight against malnutrition. As for the crop we thought of using sweet potatoes and altering its DNA to produce a more nutritious one.

Our plan is to use agrobacterium tumefaciens, cut its plasmid and insert a foreign DNA to it. Now we are stuck with what foreign DNA can we add to it so that we will produce a more nutritious sweet potato.

Our teacher gave us a hint that whatever we will add to the organism should be a protein because the DNA only codes for protein. So if we plan to add vitamins to the sweet potato then it should be protein-based.

Sorry but I am very confused with biotech terms because I am not a bio major. But any help would be very much appreciated! thank you in advance!


texts: Reasoning behind CO2 mouse euthanasia precharge prohibition

texts:
I have been at two universities now and the first permitted the precharging of a cage with co2 before a mouse is put in, but the second does not. I was wondering what the reasoning is behind the ban on precharging a cage with Co2.

When I think about this, it seems that it would be less stressful for the mice to fall unconscious very quickly rather than a slow and gradual suffocation. Is there some shock associated with the precharged cage that makes this more stressful in some way?


texts: Relation between a compound's toxicity and it's concentration level

texts:
I know that ammonia is toxic for the body since it disturbs enzymes of mitochondria.
I want to know that why the ammonotelic animals don't get affected by it?
I mean that even if there is plenty of water to remove ammonia from their body, does ammonia not cause any damage till it's inside body?
Does toxicity depends on concentration level?
Can anyone tell me its evolutionary significance?

Sorry for the previous question. .
Actually it was a easy one and I got the answer.
Sorry for the unclarity.;)


texts: What is the rate of mRNA decay in saccharomyces cerevisiae?

texts: I am just looking for a number whether that is a mean or an estimate. I am having trouble finding this value on papers because the papers mention only the methods for calculating such a value. Is there a reason why a reasonable mean is hard to obtain?


texts:
Today in class, there was a discussion going on about what part of pathogens(which can act as an antigen) can be used to make vaccines.
There was this point where our teacher said that bacterial exotoxins can be used for making vaccines.

My questions are-

Can bacterial endotoxins be used in making of vaccines?
If not,  then why is it so? What are the problems we face ?


texts:
Hi,

Why does my elisa plate wells gives a brown color after adding the stop solution. I am giving a 4*5 minutes wash after each step. TMB gives it a proper blue color but when I add the stop solution (0.16M H2SO4), the color turns to brown. I am using all the reagents new. Any help will be appreciated.


texts: What are these two nerves running parallel to the spine called?

texts:
I was looking for a human body nervous system, and often times i found a picture like the one below, where there are two nerves running parallel to the spinal column. I searched for it, but nothing came up.

Can anyone tell me what are the names to these two nerve column parallel to the spine and what are their functions?


texts:
Genetics datasets contain measurements for millions of single nucleotide polymorphisms (SNPs). Some (usually small) percentage of these values are of low confidence, and are labeled as missing values. It is common to impute these missing values using statistical relationships within the high-confidence samples as well as relationships mined from public datasets. This makes sense, to get an estimate of what that small percentage of missing data likely is in reality.

Sometimes, analyses are performed that impute up to a much larger number of SNPs - for example, a genotyping platform might measure 2.5 million SNPs, but imputation is performed to get a larger sample of 6 million SNPs. My question is, what value do the extra SNPs that were never even measured have from an analysis point of view? When performing feature selection or predictive analysis, it would seem that the imputed SNPs are really just encoding statistical relationships that are present in the dataset to begin with. What does it mean to find a highly associated or predictive SNP in the imputed set?


texts: Hybridization of an Indo-Aryan ethnic group and a Tibeto-Burmese ethnic group

texts:
The state in which I reside houses these two distinct ethnic groups.

Physical Traits of the Indo-Aryan group

Height:Medium

Eyes:does not posses epicanthic fold

Nasal bones:is not flat and broad

skin color:significant minority has fair complexion

faces:round shaped and small,but not flat.

body hair:abundant

cheekbones: not protruding

Thus the appear  as a south Asian version Caucasoid.

Physical Traits of the Tibeto-Burmese group

Height:Medium

Eyes:possess epicanthic fold

Nasal bones:is  flat and broad

skin color:significant minority has dark complexion

faces:round shaped and small,but flat.

body hair: not abundant

cheekbones:protruding

Thus the appear  as a south Asian version of Mongoloid.

Since the Indo-Aryan group has migrated recently,there is unavailability significant hybridized population.And I am interested in knowing how the offspring of inter-ethnic mating would physically look like.

But I have failed to apply laws of genetics here as I do not know which are dominant traits?

So,my question is What would be the physical traits of a 1st generation hybrid offspring  according to law of genetics?


texts: When the sister chromatids are joined in the centromere, why is it stated that the number of chromosomes is 46 and not 72?

texts: Before the DNA is replicated in a human somatic cell, the cell has 46 chromosomes. Also, after the sister chromatids are separated during Anaphase, the chromosome number in the cell doubles to 72, so when the sister chromatids are joined, why isn't the chromosome number also 72? On the internet, some sources say that one chromosome in a cell that hasn't replicated its DNA is equal to one chromatid. Is this correct, or are chromosomes and chromatids structurally different?


texts: What are the factors on which protein-protein interaction depend?

texts: Does protein-protein interaction only happens when one of them is basic and the other acidic? Do protein interactions also depend on the protein structure? Are there more factors?


texts: Does the Abbott ID NOW coronavirus test return a positive result if you take it while you're still in the incubation period?

texts: It seems like Abbott's ID Now test works by detecting the virus directly as opposed to checking for antibodies? If the test result is negative does that mean you don't have the virus? Or does that not rule out a recent infection with the virus that has not yet reached a level high enough to be detected?


texts: DNA barcoding, querry regarding tree based (cluster) methods for species identification

texts:
I am working on success rate of DNA barcoding in identification of species using distance and tree based methods.

Regarding distance based method, I have used Adhoc and species identifier and confirmed species identification using best closest match criteria (BCM).

Please suggest program/software/method for tree based identification (using NJ, parsimony, bayes), exhibiting clustering (number of clusters formed for particular species) that will suggest singleton (=Ambigious) species.

(For more details: Attached image)
(Please Note: It is not possible to do it manually as iam having >4000 specimens)

Answers detailing methods or softwares appereciated! Thank you!


texts: I'm reading a journal article about mitochondrial protein import and it mentions that one of the mutant proteins tested showed background binding with another protein. What the heck is background binding?


texts: Why are sugars like mannose expressed on the outside of eukaryotic cell membranes?

texts: Bacteria are able to adhere to sugars (e.g. mannose) on the exterior of eukaryotic cells, leading to infection and disease. Why have eukaryotes not evolved so as to dispense with sugars on their cell surfaces? I assume there must be a positive aspect to having these sugars. What is it?


texts:
I read that human started carbohydrates rich diet after adopting agriculture before that meat was main energy source which has comparatively less carbohydrate. High carbohydrate started destroying human teeth.
Would a keto diet (high protein fat) diet and low carb diet reduce cavity in teeth?


texts: What kind of beetle has fuzzy orange antennae and can flip its head down for digging?

texts: Some years ago I found this beetle while hoeing potatoes in Iowa in the United States. It had something like branches on its legs and could bury itself out of sight in five seconds! If I recall the beetle itself was mostly black.  It had the ability to flip the front part of his body up to reveal the face which was normally down facing the ground. I suppose because it usually lives underground. But when it flipped its head up, it's antennae came out and were bright orange, fuzzy ,and had round ends similar to an old-fashion side mirror on a car. When it's head was down it had a horn almost like a rhinoceros beetle.  But when it flipped its head up it had buggy eyes - the cutest little face.  I have never been able to find out what this little critter was. I just ran across my description of it in my journal today and tried to look it up online, finding your website.  Sorry, I didn't own a camera back in 2000 to take a picture of him.


texts:
According to Wikipedia, the X chromosome has approximately 153 million base pairs, while the Y chromosome has only 60 million base pairs. Thus, the difference is roughly 93 million base pairs.

My question is: Could this "extra" 93 million base pairs in virtually every single female cell of the human body slightly contribute to the "extra" relative weight of the female as a whole, in comparison to a male (of course) with a similar amount of cells? Or would this weight be so small that we can consider it negligible?


texts: Regarding Passive Aritficial Immunity: Why does the concentration of the foreign antibodies decrease over time?

texts:
So, like suggested in question, I am extremely confused about this one concept. That whether or not the injection of foreign antibodies ( passive artificial immunity ) triggers an immune response.

From what I have learnt, the general idea is that the antibodies injected into humans, which may have been extracted from another animal or synthesized artificially using hybridoma cells, act as foreign antigens to the body and trigger the cells of the immune system such as neutrophils to engulf and destroy these antibodies and anything they are binded to it ( bacteria or viruses ).

But I was doing some CAIE past papers and got confused by a question and the answers provided in marking scheme;

Question:

"Two people took part in a study to find out the effectiveness of two types of immunization. Person A received an injection of antibodies against tetanus and person B received a tetanus vaccination.

Over the new few weeks the blood from these two people were analysed for the presence of antibodies to tetanus. The results are shown in figure 5.1A and 5.1B

(b) Explain why the antibody concentration in person A,

(I) decreased during the study period,
(II) did not increase. "

The graph provided is similar to that shown in https://i.stack.imgur.com/obZ8V.png except that the rise is not seen (instantaneous) and that the x axis is in days, and most IMPORTANTLY the graph depicts concentration of antibodies to tetanus (as injected earlier).

Now the marking scheme for this question has the following guidelines for marking:

" mark (I) and (II) togeather...

(I) antibody destroyed/broken down;
    antibody excreted;

(II) no antigen entered body;
     no immune response;
     no (active) B Cells/plasma cells/memory cells;
     no antibody made; "

Now, the reason I don't understand this is because it doesn't quite align with what I have learnt. Wouldn't a foreign antibody trigger an immune response causing the neutrophils to engulf and break the antibody down.
And wouldn't the reasoning for it not increasing be that it is simply an antibody that cannot produce copies of itself as it lacks the machinery and only injection was provided, followed by its removal by the immune system?
Even lets suppose if there was an immune response, why would the concentration of TETANUS antibodies, which were injected, increase?

This is on an AS (Advanced Subsidiary Level) for CAIE.
Please, if someone can explain this concept and the answer suggested by the marking scheme, I will be extremely grateful.


texts: Is the Michael Jackson skin pigmentation disease realistic?

texts:
Quoting wikipedia:

  Jackson's skin had been a medium-brown color for the entire duration
  of his youth, but starting in the mid-1980s, it gradually grew paler.
  The change gained widespread media coverage, including rumors that he
  might be bleaching his skin. According to J. Randy Taraborrelli's
  biography, in 1986, Jackson was diagnosed with vitiligo and lupus; the
  vitiligo partially lightened his skin, and the lupus was in remission;
  both illnesses made him sensitive to sunlight. The treatments he used
  for his condition further lightened his skin tone, and, with the
  application of pancake makeup to even out blotches, he could appear
  very pale. Jackson was also diagnosed with vitiligo in his
  autopsy.

1) Is this plausible?

2) Is it likely to be an actual disease, or would there be so many mitigating factors that it is unlikely a person would suffer to the extent he did?


texts: Regulation of the concentration of precursors of DNA and RNA synthesis

texts:
What is the specific cellular process for regulating the amount of the four DNA bases (adenine, thymine, cytosine, and guanine) that are present in the cytoplasm of a cell?

Basically, how do the cell's mechanical processes "know" that there are enough of these present in the cytoplasm for DNA/RNA processes to operate effectively?

From what I understand, DNA/RNA sequence production involves simply grabbing these out of the cytoplasm as they randomly pass near the sequence assembly protein.

As a side topic, but also important here, the cytoplasm is apparently just a random fluid containing all sorts of molecules flowing and diffusing in random directions via Brownian motion. I do not know if there is a specific direction cytoplasm flows around the inside of a cell, and if so, how the cell would manage to coordinate that either.

There does not seem to be a way for cell processes to "read" the proportional molecular contents of the cytoplasm to know if there is sufficient numbers of these present for proper cell function.

If there is a lack of any one of these four base molecules, DNA/RNA processes will slow or stop functioning, leading to systemic failure and potentially cell death.

If there are too many of any one of them, the cell could become so packed that nothing can move around and the cell's function is impaired. Possibly the cell wall could rupture if there are too many.


texts: Fish, as far as I know ( of course there may be exceptions) , don't have any vocal organ...but they are proven to be social...so how do they manage to communicate with each other...on land, organisms like the honey-bee have their "tail-wagging dance"; ants have pheromones...so, what about fish?


texts: Terminology question: the scope of an allele in an organism

texts:
Let us consider a gene FOO with novel type foo.

If I were discussing an organism that has inherited foo in every cell during classical zygote formation, then I would ordinarily just say that the organism has foo.

If I were discussing a SNP of FOO that gives rise to foo in a tumor cell of an organism, I wouldn't say that the organism has foo, but I might say that the tumor has it.

If I were discussing a chimeric or mosaic organism in which some fraction of the chimera had foo and the other fraction had FOO, I would have to say something like "in foo-containing cells ..."

But what if I wanted to particularly draw attention to the scope of applicability of the allele in question? That is, I want to talk about the scope explicitly, rather than implicitly. How could I directly refer to the scope of applicability of an allele? Is there a single adjective that captures the concept of "This organism has foo in every cell except in rare ones where a point mutation may have occurred; it's probably been inherited during normal meiosis" and is there a contrasting term for "The organism only has foo in a particular subset of its cells and there is some other genetic process necessary to explain that."?


texts:
I am reading a paper and I have come across the following statement:

"Plasmids encoding full-length NCAM140 and NCAM140Δcys, intracellular
domain of NCAM140, and the NCAM140ID729–750 fragment were as
described".

I know that NCAM140 is an isoform of the NCAM protein with a molecular weight of 140kDa. However, I am not sure what Δcys means in NCAM140Δcys. Any insights are appreciated.


texts: Why don't our tongue receptors for salt and sugar adapt to them, like the ones for pepper do?

texts:
Many (most?) physiological receptors adapt to the substance they bind to, leading to higher dosages required to elicit the same response.

In pharmacology, it’s called “drug tolerance”. In physiology, “neural adaptation” or “sensory adaptation” (or simply “adaptation”).

This happens, for instance, with drugs such as marijuana, and special food items such as chili pepper.

My question is: why doesn't this happen with salt and sugar? What are the proximal (physiological) and distal (evolutionary) mechanisms that explain this discrepancy?


texts:
I need to isolate RNA from Drosophila head. I basically chop the head off and first homogenize it with a homogenizer (similar to this: http://www.omni-inc.com/omni-tissue-homogenizer-th-package-p-11.html) and further homogenize it with 22G needle in TRIzol reagent. I use TRIzol RNA isolation for larvae brain a lot and have no problem with the method itself. However, with adult I got really low RNA concentration which is weird.

I thought that maybe I have problem with homogenization itself, or I overlook something (such as extra centrifugation or different kind of homogenization etc). Does anybody have experience with it?
Thanks.


texts: I am looking for a good definition of the term "subgenomic promotor". Can someone help me out?


texts: Does loud music affect hearing and balance?

texts:
From many sources I understand that strong disturbances can destroy hair cells in the cochlea.

Does the sound damage always counts simply as the number of decibels recieved by the ear? E.g., if you listen to music in the train and you have to play it louder to hear it clearly?
Is therefore a one-shot of noise less damaging? I.e., hair cells are not as disturbed?
How long would you have to listen to the 120 dB music to lose your hearing? What is the healthy limit per day (how fast do the hair cells recover)?
Could it also affect your balance (since it is managed by the same organ)?


texts: How accurate does the alignment of molecules in DNA have to be?

texts: We have learned that the same information is saved in the DNA in the same place. So when DNA splits and then connects again (during reproduction); how does it maintain the integrity of the information? In other words, do they split and come back like a zipper, or does something else happen?


texts: What is the reason for occurence of introns in eukaryotic mRNA?

texts:
After transcription of the Template strand of DNA, in prokaryotes, the translation process begins immediately. But in eukaryotes the mRNA transcript has both non coding (introns) as well as coding (exons) sequences. So they undergo Post Transcriptional processes i.e. Splicing, Capping and Tailing.

From where do non-coding sequences arise in eukaryotic mRNA? I'm guessing its from Heterochromatin (found only in eukaryotes). Is this correct?

Also the process in prokaryotes seems to be hassle-free and simultaneous. But what is the reason for such a complicated process in the more evolved eukaryotes?


texts: Enzyme kinetics: Effect of immobilization on kinetic parameters

texts:
What is the typical effect of enzyme immobilization on the kinetic parameters of an enzyme's activity?

Can one assume that they'd stay approximately the same or is there a gross change? Any way to estimate the effect?

The native parameters are as follows:

kcat    0.5 1/min
Km      0.6 microM
[E0]    5   micro M
[S]     60  micro M

Could I expect to retain them after immobilization? Or are these too high for an immobilized enzyme?

If it matters, it is a 500 residue enzyme with a MW of approx. 65,000 Da


texts: Does fat on our heart come from the fat that we eat?

texts:
If we eat fat:

Does the fat go into heart, arteries and fat cells.

OR

Is the fat digested, following which our body creates fat that goes into heart, arteries and fat cells.

Which one is right?


texts: What advantages could there be for using the unseen variant chosen by He Jiankui instead of the naturally occurring CCR5-∆ 32 mutation?

texts:
Jennifer Doudna mentioned in https://youtu.be/9Yblg9wDHZA?t=2566 on 2019-02-21 that  He Jiankui introduced an unseen variant of the CCR5 gene when gene editing the twin humans Lulu and Nana. What advantage might there be for using that unseen variant instead of the naturally occurring CCR5-∆ 32 mutation?

Figure from the above-mentioned YouTube presentation showing the CCR5 gene and some variants:

I have crossposted the question at:

https://qr.ae/TWtxdj
https://www.youtube.com/watch?v=9Yblg9wDHZA&lc=UgwInhQJsw8lhfQBVlJ4AaABAg


texts: What causes muscles to generate heat on contraction?

texts: I'm curious what the exact cause is of dramatic heat generation that comes along with muscle activity. Can anybody explain this in understandable language?


texts:
Although farmers appear to be able to tell their cows apart, cows look very much alike to me. And this similarity in appearance seems to be a general trait across the animal kingdom: one individual of one animal species looks much like another.

Why do human facial and body shapes vary so much?

I understand that human beings live in many different environments (e.g. hot and cold) and have adapted to these (e.g. through lighter or darker skin color), but there seems to be much variation that has no apparent evolutionary purpose. So does the difference have a purpose in itself? That is, did we evlove to vary in appearance, and what is the purpose of this variation?


texts: Do foods like spicy peppers have less bacteria on their interior due to their capsaicin content? Probably not, but it seems like they could. Or I guess in other words: does capcaicin provide any benefit from anti-bacterial properties?


texts: Except for protecting ears from cold air, does a woollen cap provide any other significant advantage in winters?

texts:
I have woollen earmuffs and they are really comfy. They do the job of protecting ears well enough and I don't really have to worry about hair statics as they only cover ears and not my hairs. But many times I do get advice against using those earmuffs and wear a woollen cap instead.
If protecting ears is the only reason of wearing caps than I don't think i should leave my earmuffs but most people, though unknown of any scientific proof, claim that caps have more of a advantage than just that. Is it really so?


texts: What is this strange horned, slug-like coral reef dwelling creature?

texts:
On the first episode of BBC's Blue Planet II they visited a coral reef and showed some odd reef-dwelling creatures as part of their establishing shots, but they did not identify the creatures.

What is this odd horned, slug-like creature?
(Sort of like a slug with legs?)

I tried a Google reverse image search and it very 'helpfully' identified it as "Documentary film". So close, yet so far.

Disclaimer:
This question was split off from another question since the original was effectively two questions.


texts: Mariana Trench fish "how they can thrive under that extreme water pressure is still a mystery"

texts:
New Mariana Trench species is the deepest-dwelling fish in the ocean

Exactly how they can thrive under that extreme water pressure is still a mystery for now, but these creatures have been sighted regularly at depths of around 26,200 ft (8,000 m) and down to a record-breaking depth of 26,830 ft (8,178 m), as captured on video by Japanese researchers earlier this year.

I often see comments like this, but I have not seen any explanation why extreme water pressure would be a problem. Is there a reason?


texts: Are thunder and lightning necessary for any organisms?

texts:
Comparatively irregular events such as forest fires are necessary for some plants to grow (see here).

But do any plant or animal species have similar dependence on thunder and/or lightning?


texts: Could ions inside lungs produce hydroxyl?

texts:
I am not proficient in either biology or chemistry. However, I have a question which I can't find answer to. It seems to belong somewhere between chemistry and biology. I apologize for any errors and inconsistencies in this post.

There is a page (https://allergytech.com/sharp_plasmacluster_ion.htm) which describes a process. During this process, positive and negative ions are released to the air. They are called clusters.

  The clusters seek out and surround harmful airborne substances such as
  fungi, viruses, microbes, bacteria, plant and mold spores, dust mite
  debris, etc. At this point, a chemical reaction occurs, and the
  collision of hydrogen with oxygen ions creates groups of highly
  reactive OH radicals, called hydroxyl - Nature’s form of a Detergent.

  A hydroxyl radical is very unstable. To stabilize itself, it robs the
  hydrogen from any harmful airborne particles it encounters. Doing so,
  the hydroxyl radical damages the harmful micro organisms and
  deactivates them.

Below is my question.

Suppose that a human breaths in those clusters as soon as they are released to the air. Is there a possibility that inside lungs, they will encounter something that will trigger similar reaction, and in effect hydroxyl will be created, too?


texts: How to retrieve full gene names list and Entrez gene IDs and other annotation information from HUGO gene name list (in R or any)?

texts:
How to retrieve full gene names and Entrez gene IDs and other annotation information from HUGO gene name list (in R or any other software or language)?

Is it possible vice versa: having full gene names or IDs get HUGO names or the other annotation data?


texts:
The heterochromatin is generally localized at the nuclear periphery (also near nuclear lamina), whereas active genes are preferentially found in the nuclear interior.

Children with Hutchinson-Gilford syndrome have a mutation in a LMNA gene, which codes lamin A and C, therefore, mutation in a LMNA gene causes overexpression of genes near nuclear lamina, this shows that nuclear lamina has something to do with gene expression regulation.

What is the mechanism by which lamins regulate gene expression?


texts: Neuroscience of temperature regulation and perception

texts: The hypothalamus is known to be important in the regulation of body temperature, but I'm curious whether anyone knows about the neurocircuitry of perceived temperature. It seems like there could be a difference between how warm/cold someone feels and the temperature to which their body is trying to adjust. Intuitively, I'd imagine that any apparent difference in these  has to do with some sort of delayed feedback that is experienced before the autonomic nervous system can kick in. Does anyone know something more about this?


texts: The evolutionary process in bird wings, especially with regard to winglets

texts:
In this answer on aviation.SE a comparison is made between the shapes of airplanes wings and the shapes of birds wings. It concludes with the following remark:

  After all, no bird has winglets. Not a single one.

In addition to be a disputable assertion (the wing tips such as the eagle's could be considered akin to a "winglet" of the fanned type) this has stricken me as based on a quite wrong assumption of how evolution works.

I tried to make my point in the comments only to reach this point:

  So you consider evolved wings as not mature. The winglet modification is just waiting to happen? Nature never tried it, in >100 million years of biological flight? Could be, yes. But is extremely unlikely. That settles it for me.

Am I correct in identifying this in a wrong interpretation of the evolutionary process?

As I understand the evolutionary process, the current bird wings are not necessarily perfect, are simply the version that so far has given the best advantage. The lack of "winglets" in birds cannot then be explained simply by assuming that they do not improve the wing, but it could also be that there has never been an evolutionary pressure to evolve them or that since birds flap their wings they would be detrimental instead of beneficial or whatever other reason.

Is my understanding of the evolutionary process correct? if not, where am I at fault?

As a small addendum, another user cited the "Spandrels" in comparison to the above debate, could someone explain what could have been the meaning of the comparison?


texts: Is it possible to discriminate tetrachromacy using sRGB color?

texts:
Hi I'm a physics grad student who has lots of interest on color perception.

I have recently learned that some people (mostly women) have another active cone cell which makes them possible to discriminate more colors than usual people like me.

Is it possible to discriminate tetrachromacy using sRGB color, I mean, is it possible to test it out on computer monitor? I guess so, because even though computer use combination of only 3 colors, it seems possible to make 2 combinations different in which is only perceptible to tetrachromacy. However, I'm not sure about that point because I'm not expert on that.

Anyway, if I'm right, it would not be so hard to make a test which resembles dyschromatopsia test, that can distinguish trichromacy and tetrachromacy. I couldn't find such a thing on internet. Test I could find seemed not valid. Even I could pass all the tests, but I'm not clearly tetrachromatic person.

Can somebody help me?


texts:
From what I understand of Crickets, they lay their eggs in dirt and hop away and that is their parenthood.

But in the past month (since I moved into this apartment) I have found 1 adult cricket and half a dozen tiny baby crickets in my bathtub on THREE SEPARATE OCCASIONS.

There have been times I have found other adult crickets in the tub, I have never found a baby cricket in the tub alone.

Something is going on here that doesn't track, an adult cricket could easily get into the standard 18 inch-ish high bathtub, but these baby crickets are about 2mm long and can jump upwards of about 3 inches from my testing.

Why/How are they traveling together?  What is the gestation on crickets?  Is it short enough that she lays the eggs at night and they hatch by mid morning?   Are they coming up the drain?  Carrying their brood on their backs because this is Arizona and they learned it by watching scorpions?  I need answers! This is the weirdest mystery of quarantine, and it must be solved.


texts: Why are there so few multicellular anaerobes?

texts:
There are a few documented cases of multicellular anaerobic organisms, but I can't see a reason for it to not be more common. On the contrary, it seems pretty useful to be able to create energy even when deep inside tissues, yet the Loricifera are the only ones I've found documented. Given how often multicellularity has arisen, is there something that's fundamentally difficult about being anaerobic while multicellular?

One thought that might inspire others- multicellular organisms certainly tend to be bigger than unicellular ones, and in an oxygenated world larger organisms are more likely to run into oxygen than unicellular ones. However, there still exist an abundance of anaerobic niches for large organisms- the deep sea, for example.

I'm also drawing a distinction between facultative anaerobes and obligate anaerobes- there are plenty of facultative multicellular anaerobes, and I'm not as curious about that.

Useful sites that I came across while searching:

Journal article announcing the first anaerobic metazoa

Anaerobic fungi, presumed to be unicellular?


texts: Why are melodies/harmonies perceived as pleasurable by humans?

texts: Is there any evolutionary advantage to finding melodies or harmonies pleasurable? Does the ear pick up these particular oscillating waves differently from other sounds, and if so, how does that affect our perception of pleasure? I'm looking for some sort of signalling pathway (most likely involving neurotransmitters I realize).


texts: Which strains of C. diphteria are causing Diphteria toxin?

texts:
I got this question:

Diphteria toxin is produced only by those strains of C. diphtheria that have which of the following characteristics?

Encapsulated
glucose fermenters
lysogenic for b-prophage
only mitis-strains
sucrose fermenters

I think the right answer is lysogenic for b-prophage, since Freeman found out that toxic gene is encoded by lysogenic phage infecting all toxigenic strains in 1951.
However, I am not sure what "b-" means in "b-prophage".

Which part is "b-" in Prophage?


texts: Should I use glycogen in isopropanol to precipitate RNA or does glycogen have harmful consequences on downstream protocols such as RNA seq?

texts: I have heard that one can use glycogen in isopropanol to better visualise the RNA pellet after centrifugation. What are the advantages and disadvantages of adding glycogen in isopropanol for RNA quality and quantity?


texts: need to identify species of this Leaf-footed bug?

texts: I found this bug in Pune/India. I checked many species of leaf-footed bugs, but none of them is matching this one. It was about 3cm long. It was not showing any movement.


texts:
I found a very interesting branch last week, and have been trying to identify it but cannot seem to find the answer. If anyone has any suggestion, I would be grateful.

I found it near the forest, around WA area.

Here's some picture:


texts: How should lentil roots grow in a microgravity system?

texts:
I recently executed an experiment in which I collocated 20 lentil seeds in independent Petri boxes with an agar agar solution, all of it located in a clinostat (a slowly rotating device used to simulate microgravity conditions, where they rotated perpendicularly to the ground (gravity). The objective was to see in what direction did the roots grow under the effects of microgravity, since geotropism didn't have a fixed direction to head to. At the end of an entire cycle, the forces (gravity in 360°) applied to the seeds would turn out to be equally strong, in opposite directions, so it would come down to nearly zero.
However, after many executions, without having any functional problem with the clinostat, the seeds simply didn't grow roots while being in the agar agar in the Petri boxes. I tried different agar agar solutions, different concentrations, more & less quantity so that the seeds would have a thin air layer; and I also added copper sulphate to prevent fungi from appearing, also varying its concentration. Afterwards, I tried using an already germinated seed so that the radicle had direct access to the solution and to the air layer. Nevertheless, after several executions, only a few seeds grew their roots and I din't find a concrete explanation for this experiment not being successful.

I expected having the roots in the experimental group to grow in many different directions, not being constant. As in the other hand, I expected the control group to grow roots in the same direction, going downwards, being in the same system (clinostat) without having the rotations going on.


texts: I found this fly in Bengaluru/India. It was larger than usual flies. It was more than 1cm in size, with black color which has blue shades in it. I managed to take just this one pic, then it flew away.


texts: How does the composition of blood cell types in human blood change during our lifetimes?

texts:
I was reading the paper Age-related accrual of methylomic variability is linked to fundamental ageing mechanisms.

There they do additional checks to see that their results are not due to differing cell type composition in blood that happens as we age.

That made me wonder, how does the cell type composition of our blood change as we age? Is it known? (I guess we would get less hematopoietic stem cells, but I do not think they are in the blood themselves.)


texts: What method of breathing provides a sudden surge of oxygen into the lungs filling it as full as possible in volume and density. Deep breaths? Shallow breaths? Breaths taken while bent over? Deep inhales followed by further inhales. Breaths held? Movement while breaths are held?


texts: Will modern-day insects grow to massive size in a high-oxygen environment?

texts:
It's a reasonably well-known fact that insects grew to massive sizes due to the excessive concentration of oxygen in the prehistoric-Earth's atmosphere.

If one were to try to recreate this high-oxygen environment in a lab setting, would insects reared within grow to massive size?


texts: Can in the case of multiple sclerosis (MS), a too high osmotic pressure in the nerve, lead to a high intracellular concentration of potassium?

texts:
Can in the case of multiple sclerosis (MS),
a too high osmotic pressure in the nerve,
lead to a high intracellular concentration of potassium,
and also lead to 'pumping up' of nerve cells,
which then due to the strongly increased internal pressure,
the insulating myelin sheath can be pressed broken,
resulting in a lesion,
or a strong reduced transmission of stimuli ?

If that were to happen,
one can expect in cerebrospinal fluid,
cytokines, which are normally also a component of the nerve cell contents,
and that it wrongly can be interpreted,
as inflammatory reaction to a potential autoimmune disease.

Is there research of this ?


texts: Why do Indian Major Carps spawn in running water?

texts:
I think running water serves as a cue necessary for hypothalamus to release GnRH into hypophyseal portal system which initiates a cascade of hormone actions ultimately leading to release of gametes.

I have looked up in Internet with no results. I guess no work has actually been done to discover the reason. But as it's an assumption I would like to here from anybody more specialised.


texts: Effect of increasing Extracellular Na+ Concentration on resting voltage and likelihood of an action potential of occuring

texts:
If you increase the extracellular Na+ concentration how will this effect the resting voltage and likelihood that an action potential of will occur?

Please explain using the Goldman–Hodgkin–Katz voltage equation if you have that understanding.  I can typically understand mathematical functions and relationships.

My guess is that the membrane will become more hyperpolarized and the likelihood for an action potential will go down.  I have read some explain otherwise and I would like help confirming or denying my current understanding.


texts: Conserved acetylation sites in a given protein

texts: I want to identify potential conserved Acetylation sites in protein X. As it is known, acetylation happens in Lysines (K), thereby I would like to identify conserved K residues for protein X during evolution. Eventually I would use different Acetylation site prediction tools to further filter the results, but initially I need the other data, does anyone know a user friendly but trust worthy bioinformatic tool to do so?


texts: Do breasts size depend solely on fat amounts?

texts:
I've read the first answer here on quora and it suggests that (not during pregnancy and breastfeeding) breasts differ in size only due to the amount of fats. However, there can be firm or soft breasts of the same size and this is somewhat disputing the claim. Also, women with firm breasts can find it painful when their breasts are squeezed while those with soft breasts are less likely to have the same experiences.

So, what makes breasts firm or soft given the same size?


texts: How does better sperm result in more viable offspring?

texts:
Quoting wikipedia:

  Greater choice and variety of mates increases a female's chance to produce more viable offspring.

This led me to the question: "How sperm parameters are connected with entity parameters?"

Actually, sperm parameters are usually: motility and morphology. I am speaking about a single sperm, therefore any parameters involving their count or parameters of semen are not included.

On the other hand, what helps a particular entity to survive is determined by many parameters. Some of them are: speed, endurance, strength, agility, stealthiness and savvy. It is hard to find out how strength of being is connected with motility or morphology of sperm it has been conceived. And even less obvious is the connection of stealthiness with such sperm parameters.

But since sperm competition exist, it helps in natural selection, therefore there must be a connection. But how does it really work? How are stronger/faster/stealthier/etc. entities are the product of more motile or better in morphology sperm?

After some thinking about it I think that if there is some correlation between sperm parameters and genome, it can answer the question. E.g. presence of gene that increases fitness of organism makes sperm faster.


texts: How long can Vibrio cholerae live in its ambiental optimal context?

texts:
How long can the Vibrio cholerae live in its ambiental optimal context?

Thank you in advance. My problem is that i can't find this information. I did some research on google, but nothing was retrieved, I even used other search engines. Thank you very much for your help.


texts: Why does a pacemaker have a negative pulse?

texts: Why is the first phase of the pulse from a pacemaker cathodic?


texts:
Here is a video that will show the behaviour I'm interested (see between 12:30 and 12:32).

I want to know if this behaviour has a name and why birds are doing this. I observed this many times, with offsprings getting fed, females and males adults. I'm curious about studies that looked at that behaviour.


texts: A study has found that cell phones cause infertility, is this something to worry about or is the study flawed?

texts:
Is this a worrying study, or is it flawed?
A study has found that cell phones are detrimental to male sperm quality (Lower sperm motility and sperm concentration). It’s original goal was to determine if image content has a effect on sperm quality, but accidentally discovered that men who said they kept their phone in their pocket had worse sperm quality than those who didn’t have a phone in their pocket. As far as I can tell, from my limited knowledge, the study isn’t very flawed. What I do know is that they used 52 men, which doesn’t seem like a lot.
Another possible flaw is in regard to how they took sperm samples. Sperm parameters can vary amongst healthy individuals, the WHO recommends taking at least 2 samples to determine fertility. This study took one sample from all 52 men, then asked them if they wanted to participate the second time around and only 25 men agreed. So, they did take more than one sample but only for 25 men. I’m not sure, but this doesn’t seem like very good methodology as only 25 of the samples are representative.
Another issue is that the study had a variable that it changed from person to person. As stated, it’s original goal was to find out if image content affected sperm quality, and they concluded that it can. They gave different images to each mam, meaning that some of the images would have had a detrimental affect to the sperm quality. So, they could have gave a healthy cell phone user a type of image that causes poor sperm quality. However, it would be coincidental that cell phone use was still correlated with poor sperm, even if the study randomly gave out out different images to different people that could cause poor sperm in the analysis the ones with poor sperm.
I was wondering if certain lifestyle factors that tend to be associated with phone use where causing the infertility, not the phones themselves, but the study had a very extensive questionnaire and adjusted for many different factors from bathing habits to diet, so I don’t think that the study can be flawed in this are. What do you guys think? Is this something that we should be worried about and change our habits over, or is it scientifically limited and no cause for alarm until bigger and better studies conform their findings?


texts: Why are female not competitive for reproduction like males?

texts:
I have wondered if competition for mate among males and the race among sperm cells would result in healthy offspring,

why no such mechanisms exist among females and egg cells?

(Even females are genetically responsible for the offspring.)


texts: What type of CCD system is required to take photos of luciferase

texts:
I'm working with luciferase and I want to be able to take a photo of it. The trouble is, I can see the luciferase glowing in all of its glory in front of me but no matter how hard I try, I can't take a photo of the luciferase with my DSLR (Nikon D80).

I'm curious if I'm missing a certain lens or if I should be shooting using a different lighting setup. I'm already exposing for 30". Perhaps longer?


texts: Does Rüppell's Griffon Vulture Have Greatest Vision Acuity? (Small Carrion Spotted at 10 km+?)

texts:
Synopsis:

Some sources seem to imply the Rüppell's (griffon) vulture (Gyps rueppelli) can see objects at a distance in excess of 10 km -- roughly three times the commonly asserted vision distance of an eagle.

What studies have been done on eyes of this species and can any experts comment on the accuracy of this assertion?

Also, do we know whether their eyes perceive a similar color range to that sensed by human photoreceptor cells?

Background

Wikipedia's List of birds by flight heights lists the flight height of Rüppell's (griffon) vulture (Gyps rueppelli) as the highest known bird flight height at 11,300 m (37,000 ft).

The claim appears based on this ornithology journal article [PDF]
 ("Collision between a Vulture and an Aircraft at an Altitude of 37,000 Feet") detailing a collision over Abijan, Ivory Coast.  This is a coastal city...

...so can be estimated to be approximately at see level, inferring this is a height above ground (roughly).

The article adds:

  Vultures use their excellent eyesight to scan the landscape below from a relatively static aerial position. Instead of flying over a larger distance, they use elevation to expand their field of vision. If they spot a meal down below, the climb has an immediate payoff.

That piqued my interest, as I came across this while trying to track down what the maximum known distance an animal could see was (per a separate discussion of fantasy vision capabilities).

Human vision is according to quantitative testing limited to "~2.6 km (1.6 miles)" [synopsis], likely varying mildly based on physiologic variability.

A Wikipedia entry on eagles ("Eagle Eye") states (citing a book on eagles as its source):

  The eagle eye is among the strongest in the animal kingdom, with an eyesight estimated at 4 to 8 times stronger than that of the average human. An eagle is said to be able to spot a rabbit 3.2 km away.

The statement is a little bit tenuous on the sourcing, but impressive if reasonably accurate.

The note in the list of highest flying birds, though, makes it sound like this high-flying vulture could be able to detect faint objects at a distance of 10+ km!

That in turn suggests this bird to have perhaps the longest range vision acuity of any known species, with a vision range perhaps three times that of an eagle or more.

If so, the record for animal vision would not be "eagle eye", but rather "vulture eye".

Granted, it might also all be bunk; the internet is a very inaccurate place hence why I came here to StackExchange seeking quantitative evidence in support of this claim.


texts: Is there a standard reference for the importance of tumor heterogeneity?

texts:
In a recent post, Philip Gerlee highlighted the two biggest contributions of mathematical oncology to cancer research: (1) increasing focus on the progress of cancer as an evolutionary process, and (2) looking at the importance of tumor heterogeneity.

For the first point, the standard historical reference is: Nowell, P. C. (1976). The clonal evolution of tumor cell populations. Science, 194(4260): 23-28.

However, for the second point, although I am vaguely familiar with modern work, I don't know of a historical reference. When was tumour heterogeneity first recognized as important to cancer dynamics and treatment? Was this work related to mathematical or other modeling insights? If not, what is the first important mathematical (or computational) modeling work on tumour heterogeneity?


texts: Concentration/molarity of lichen acids (particularly oxalic acid) in soil/rock substrates?

texts:
I am trying to design an experiment testing the efficacy of lichen acids to solubilize and mobilize nutrients from minerals in a lunar regolith simulant. My research so far indicates that oxalic acid and citric acid are especially important lichen excretions in this process, but I am struggling to find resources detailing the concentration of these and other organic acids in various lichen species. The closest is finding very general indicators of concentrations (i.e. between 0 and 15mM for "lichens").
Does anyone know of any resources or databases that detail organic acid concentrations in different lichen species? Am I pursuing this from the wrong angle? Any input is appreciated!


texts: How do *Polistes sulcifer* (cuckoo paper wasp) eggs hatch so quickly?

texts:
The Polistes sulcifer wasp is a brood parasitic species, which parasitizes colonies of the paper wasp Polistes dominulus. During an extremely brief time window in the spring, just before the P. dominulus workers have emerged, the P. sulcifer female will invade a P. dominulus nest. Once inside, it will kill or evict the host queen, ensure its cuticle hydrocarbon profile will not lead to its being attacked, and then lay its own eggs. It will rely on the host workers to tend to these.
(Note: I don't know whether it just alters its own hydrocarbon profile, or whether it also alters that of the nest. It's tangential to this question.)
The P. sulcifer wasp needs to time its attacks precisely. If it invades too late, the workers will have emerged and the colony will have a lot more wasps to defend it. If it invades too soon, there will not be enough host workers emerging to tend to its brood, especially if the host queen has not laid many eggs. P. sulcifer itself does not have a worker caste, and so is entirely reliant on host workers.
Research published in 2004 (paywalled, unfortunately) showed that the parasite wasp eggs took an average of 5 days to hatch after being laid, with the minimum observed being 3 days. This was in marked contrast to the host eggs, with average time 8.6 days in an unparasitized host colony, and 9.1 in one which was parasitized. Likewise, the parasite larval stage was much shorter, lasting an average of 9.8 days as opposed to 16.6 for host larvae in a parasitized nest (14.8 in an unparasitized colony) and the pupal stage also slightly shorter.
The parasite larvae were able to attract more attention from the workers than the host larvae - including being fed more often - which would appear to offer an explanation for the faster larval development and shorter larval/pupal stages. But this does not explain the shorter egg stage. Rapid development is clearly advantageous in terms of maximising the number of offspring produced, so a shorter egg stage is advantageous to the parasite, but the mechanisms behind this short incubation period are not known.
In the famous example of an avian brood parasite, the cuckoo, the parasite eggs also hatch more rapidly than the host eggs. This is, at least in part, because the female cuckoo holds the egg in her oviduct for an additional 24 hours prior to laying, at a higher temperature than an egg being incubated in the host nest. This gives the cuckoo egg the equivalent of a 30 hour head start on the host eggs.
In the aforementioned 2004 research paper, it was speculated that the wasp might use a similar mechanism, but this was not known, and no research into this had been carried out. A later 2006 paper also stated that no information was known about this, and I have been unable to find any further research on the topic.
Has there been any subsequent research into how P. sulcifer has been able to ensure its eggs hatch abnormally soon after being laid?
Sources - paywalled:
Cervo, R., Macinai, V., Dechigi, F., & Turillazzi, S. (2004). Fast growth of immature brood in a social parasite wasp: a convergent evolution between avian and insect cuckoos. The American Naturalist, 164(6), 814-820.
Ortolani, I., Turillazzi, S., & Cervo, R. (2008). Spring usurpation restlessness: a wasp social parasite adapts its seasonal activity to the host cycle. Ethology, 114(8), 782-788.
Sources - non-paywalled:
Cervo, R. (2006, January). Polistes wasps and their social parasites: an overview. In Annales Zoologici Fennici (pp. 531-549). Finnish Zoological and Botanical Publishing Board.
Cervo, R., Dani, F. R., Cotoneschi, C., Scala, C., Lotti, I., Strassmann, J. E., ... & Turillazzi, S. (2008). Why are larvae of the social parasite wasp Polistes sulcifer not removed from the host nest?. Behavioral Ecology and Sociobiology, 62(8), 1319-1331.
Other sources:
Davies, Nick B. (2015). Cuckoo: Cheating by Nature. Bloomsbury. ISBN 978-1-4088-5658-1.


texts:
How does the digestive acid (HCl) not burn the surrounding membrane of our stomach? It digests the majority of raw food we eat but how does it stay safely in our stomach?

Also, how does the stomach maintain the ability for a human body to retain HCl for all lifetime?


texts: How do we know Denisovans had 46 Chromosomes

texts:
What allows sequencers to conclude that Denisovans had 46 chromosomes rather than merely knowing Denisovans had the crossover material arranged in 48 or say 44 chromosomes?

See http://genetics.thetech.org/ask-a-geneticist/denisovan-chromosome-2

What I am asking its what allows sequencers in this case to make an inference to an actual number of chromosomes (packaging) rather than the mere presents of corresponding DNA?

In the article above, interbreeding was rejected as a sufficient condition for inferring equality to humans in chromosome number and the author points to a man in China known to have the same cross over (fusion) known in humans and only 44 chromosomes indicating having the cross over that reduced 48 to 46 is also not a sufficient condition for concluding 46.