texts: Are lactic acid and prolactin rise after exercise connected?

texts: I've been reading about prolactin, a human hormone. Apparently it's levels within the brain can raise after exercise, although the mechanism is not clear to me. I'm interested of there is any connection between lactic acid build up in muscles during anaerobic exercise and prolactin levels in the days following exercise. Both of these sound similar, which may be a coincidence.


texts: Some introductory biology textbooks state that sometimes the body cavity is formed from pouches pinched off from the endoderm. So, I am interested in understanding  what 'pouches pinched off' actually means? Also, are platyhelminthes triploblastic or diploblastic (my professor says that they are diploblastic but books write that they are triploblastic).


texts: Appropriate regeneration of StrepTrap HP columns for FPLC

texts:
My question is related to protein purification using a ÄKTA FPLC.
We used StrepTrap HP Columns (1 ml column Volume (CV)) from GE Healthcare Life Sciences to purify a strep-tagged protein. In the first approach, this worked pretty fine.
We wanted to re-use the columns after regenerating them according to the official protocol. The included steps were all performed at a flow rate of 1 ml/min and with filtered solutions:

3 CV distilled water
3 CV 0.5 M NaOH
3 CV distilled water
5 CV 20 % EtOH
Storage of columns in 20 % EtOH at 4°C.
Equilibration of the columns with Binding Buffer just before next use.

By adhering to the protocol we encountered some problems with the next purification (it was the same protein, but a new sample of cell extract). The purification worked less effective and the amount of purified protein was very low.

We tried a slightly different protocol for regeneration, also at a flow rate of 1 ml/min and filtered solutions.

5 CV distilled water
5 CV 20 % EtOH
3 CV 6 M Guanidinhydrochloride (sol.)
5 CV 0.5 M NaOH
3 CV distilled water
5 CV 20 % EtOH
Storage in 20 % EtOH at 4°C
Equilibration with Binding Buffer before next use.

We chose the Guanidinhydrochloride to denaturate all remaining proteins from the column resin and support the regeneration by this.
But also with this protocol we encountered the same problems (low efficiency of purification).

I would be very interested if anyone of you have encountered the same problems and maybe have a solution/better protocol for this regeneration step.

Thank you for your suggests in advance! :)


texts: If you measure the O.D. of cells at one wavelength, is it possible to find its equivalent O.D. at another wavelength?

texts: For example, I measured the optical density (O.D.) of some cells at wavelength 550 nm but I should have used 600 nm. Is there a way of converting my O.D. to its equivalent in another wavelength?


texts:
I am sorting some pictures and found this one taken from Swiss Jura Mountains (North part, alt ~700m) in March 2013.

The day before I saw a Dendrocopos major (Great spotted woodpecker) and without looking thoroughly before I though it would be a young one.

Now when I examine in more details the picture it seems to be a Dendrocopos medius (Middle spotted woodpecker).

Am I right? Can someone confirm this?


texts:
Because Ebola takes over the immune system and uses it to replicate more and more of the virus, how does the body survive?

Is it a case of the virus being self-limiting and eventually just getting 'too big for its britches' so to speak? Or does the body somehow eventually start producing antibodies to fight it off?


texts: Chlorination has been used for over a century to disinfect water supplies. Why haven't microorganisms evolved immunity to this chlorine by now?


texts: functional hypocholesterolemia due to very high HDL or low LDL?

texts:
Nutritional and medical recommendations about cholesterol seem to focus exclusively on hypercholesterolemia, and as such, they provide only a maximum desirable level for LDL and a minimum for HDL. I've found a little bit of information about hypocholesterolemia caused by inadequate cholesterol in the body (due to overuse of statins, malnutrition, or other disorders), but not about cholesterol deficits due to lipoprotein levels.

It seems like it should be theoretically possible to have so much HDL or so little LDL activity that organs don't maintain enough cholesterol to function properly, even if cholesterol synthesis is adequate. Obviously this might or might not ever occur in reality. Is there any research that has found an upper bound on desirable HDL in humans, or a lower bound on desirable LDL or LDL:HDL ratio?


texts: Why are potassium channels slower than sodium channels?

texts:
I am relatively new in the subject of biology. I have a strong mathematical background and in order to get into the field of computational neuroscience, I am trying to get some biological background.

I am reading about the general mechanism of action potentials in neurons.
I understand that an action potential starts with a fast entrance of sodium into the postsynaptic cell. Since the potassium channels are slower than the sodium channels, potassium starts flowing out of the cell only around the peak of the action potential, thereby hyperpolarizing the cell's membrane potential.

What is the mechanism that causes the potassium channels to activate slower than the sodium channels? Does it involve differences in the behavior of the suitable neurotransmitters? Because I didn't manage to find transmitters or couples of transmitters and receptors which activate potassium channels, but not sodium channels (or sodium channels and not potassium channels).


texts:
While hiking through one of the areas burned in the 1988 Yellowstone fires, I noticed that some of the trees appeared to have grown in spiral patterns.

Most downed trees have crack patterns that imply straight growth, but some look like the one in the picture.  The direction shown in the picture seems to be more common, but it's not universal, and it doesn't appear to be related to location -- another picture I took shows two adjacent logs that spiral in opposite directions.


texts: I was wondering... If Ebola attacks immune cells and causes immunosupression, then shouldn't we see death in Ebola patients due to secondary infection?


texts: Which texts are good for beginners to understand evolution on the genetic scope?

texts:
Are there good texts to study the evolution, how it works, and how mutations and changes lead to evolution of the organism ?

And how does the information increase through the long time using mutations and other mechanisms?

Can you recommend specific texts?


texts: What happens to deep sea creatures if they reach the surface?

texts: Since deep sea creatures are adapted to incredibly high pressures, I would assume they would not be able to survive in the low pressure environment of the surface.  What exactly happens physiologically to a deep sea fish if it reaches the surface?  Would cell walls rupture?


texts: How fast can the human body temperature change?

texts:
I'm really curious about how fast can a human body temperature change?
E.g. how fast can the human body temperature change when the human has fever?

I'm not interested in how fast fever changes the temperature, more likely how fast the human body is possible to change it?

I found allot information about how much the temperature changes over the day and so on, but now how fast the human body is "capable" to change it in a certain time span.


texts: Specifically, I'd like to look at changes in HA (hyaluronic acid) production. Most often you only see people staining the cell surface or removing cells from culture for fixation and then imaging. Does anyone know how to analyze the ECM (extracellular matrix) and proteoglycans that surround a cell if you're looking to see if a condition may be changing the way a cell remodels it's ECM? Is it even possible with some fluorescent tags?


texts:
Recently in Eastern Pennsylvania, there has been lots of rain and heat (90's) for a couple weeks now, so lots of mushrooms are popping up.
A neighbor posted a picture of this fungus in a community group, and was wondering if it is edible.


texts: Can saltwater fishes survive in sugar solution?

texts: I know saltwater fishes can't survive in freshwater because of osmosis that water would rush into the body of fishes. How about sugar solution? Does sugar solution provide similar conditions as salt water for saltwater fishes?


texts: I know that dicumarol was discovered in moldy sweet clover as it caused hemorrhage in cattles, but if someone had thromboembolic disorders causing uncontrolled thrombosis,would it be fine to eat moldy sweet clover (in case of absence of any means of modern life) especially that it contains other microorganisms?


texts: Amount of animals to use for animal trials

texts: I am working on an independent research project involving animal models. I am unsure how to deterine how many animals (rats) to use for the project. The rats will be injected with different solutions to examine the effect on a target. There is nothing in the literature about trying any of the solutions in rats. How do I determine the amount of rats to use?


texts: How much does the nutritional value of insects depend on what they're fed?

texts: Insects are often touted as being the food of the future due to their nutritional value and small amount of resources required to raise them. However, how dependent is the nutritional value of an insect on what they are consuming. How many vitamins and amino acids are they able to synthesize?


texts: If overcooked hard boiled eggs show these green sulfide rings, why do scrambled/fried eggs not show this?

texts:
In the image above, the dark green rings are ferrous sulfide rings, caused when the sulfur from the egg white reacts with the iron in the egg yolk when the egg is overcooked.

I was wondering, given the same circumstances, why do we not see our scrambled/fried eggs coated with this layer of ferrous sulfide?


texts: What triggers the release of gonadotrophin-releasing hormone with the onset of puberty?

texts: I am interested to know the process of development of puberty. During puberty, when boys/girls reache 12-14 (puberty) years of their age, their hypothalamus releases gonadotropin releasing hormone (GnRH) and then this hormone in turn affects the pituitary gland which releases FSH and LH. FSH/LH hormones promote male/female features. For e.g. girls start their first menstruation cycle and males start to produce sperm; their voices become smooth and intense respectively. So all these phenomena are dependent on GnRH.My question is that if those hormones are produced due to the effect of GnRH then how is GnRH production itself regulated. In other words how does our body "know" that we are in the age of puberty and it should secrete GnRH?


texts: How do amino acids become attached to tRNA?

texts:
Is there a protein that catalyzes this or does it happen spontaneously?

In which part of the cell does this happen?


texts:
The first electron source for plants was H2S, but now most modern plants use H2O as an electron source.

What is the advantage of using H2O instead of H2S?


texts: These creatures, fly and walk, and have perfect eyesight and follow me everywhere I go.  They have many legs, they are about 1 inch and their color is almost translucent, but a very light shade of brown.  They smell me at all times and bit me like a mosquito.  I have used 2 pesticide companies to exterminate, but no one is able to identify the critter so I can't kill them.  They also have a very strong heartbeat. I know because they like to be under me.  They move so quickly that I haven't been able to catch a picture.  Please help me to identify these nasty things, so they can be destroyed.


texts: Why do humans sneeze out mucus if it's a good thing?

texts:
The Wikipedia article on mucus says that mucus acts as protection from bacteria and other microorganisms.

Given that mucus plays this positive role, why do humans sneeze out mucus?


texts: What are the hairs/spikes on the edges of these leaves for?

texts:
Windows 7 has a wallpaper/background which shows an attractive, leafy plant with fine hairs or spikes on the edges. What might these be for, and what sort of plant is it?

My initial (uneducated) guess is some species of Sempervivum, with the hairs serving some purpose like water-collection?

Windows 7 leaf background http://p1.pichost.me/i/32/1555532.jpg


texts: How are ants able to dig with such pointy limbs?

texts: Digging is usually efficient with somewhat broader structures shovels, no one tries to shovel with an ice-pick. Given that ants have very pointy mandibles and thin wispy legs, how are they able to dig anything? Is it  honestly solely by the means that the granules of soil are somehow coincidentally always the right size to fit in their mandibles?


texts: Are there wounds which never completely heal?

texts:
I have a cut on a knuckle which occasionally opens (usually during winter), to disappear after some time (it is usually fine during the summer). This is going on for years now and yes, I will show this to my doctor (it is more a nuisance than anything else but there is the risk of infection).

Then during a recent discussion about the Vietnam War, the story of Phan Thi Kim Phuc was mentioned and I recall that I read years ago that she said (quoting from memory) that "[her] wounds still open, usually in summer".

I was wondering what is the mechanism of such wounds which heal, but not completely (to reopen after some time or on some conditions).

Her story is horrific and the extent of her wounds (and also the nature of the wound - inflicted by Napalm) make me think that there may have been some changes in the skin so deep that the consistency of the skin is not there anymore (wildly speculating).

In my absolutely minor case, however, there are no particular reasons for the wound to open - it is just closed and then, sometimes, decides to reopen to re-heal some time afterwards. Since this is otherwise healthy skin (it looks perfect when the cut is closed) I wonder if there are mechanical or chemical reasons for these behaviours?


texts: What happens to human dopaminergic reward system once a teenager becomes adult?

texts:
I've recently heard a podcast which explained teenage impulsivity and novelty seeking in part by

"Lowering the baseline dopamine activity in the reward system"
"Increase in dopaminergic reward in response to novelty"

I assume that by reward system the author means mesolimbic and mesocortical dompaminergic pathways in the brain.

Here's an article that seems to state similar findings:

  Starting in early adolescence and peaking midway through, this
  enhanced dopamine release causes adolescents to gravitate toward
  thrilling experiences and exhilarating sensations. Research even
  suggests that the baseline level of dopamine is lower—but its release
  in response to experience is higher—which can explain why teens may
  report a feeling of being “bored” unless they are engaging in some
  stimulating and novel activities.

The dopamine system here is being compared to the child's dopamine system. I'm interested in what happens to the dopaminergic system once a teenager/adolescent becomes an adult at around the age of 24-25?

I'm looking for insight along these lines - does the reward system of an adult "settle down" and no longer respond to novelty as strongly? Is the baseline dopamine level higher?


texts: "bead" on a string theory of genetics, source?

texts:
Thomas Hunt Morgan was a pioneer in genetics and proposed the now false model of genes being "beads" on a string. These beads being indivisible and responsible for a single phenotype, if I understand correctly.

Does anyone know of a good, reputable source of information on this theory that would be sufficient to use as a citation? I would use wikipedia, but it is disallowed.


texts: Do ants really dispose of their own dead, and how/why?

texts:
I just read this from Wikipedia's Swarm Behavior article:

  Despite the lack of centralized decision making, ant colonies exhibit complex behaviour and have even been able to demonstrate the ability to solve geometric problems. For example, colonies routinely find the maximum distance from all colony entrances to dispose of dead bodies.

There was no citation.

Is it true that ants dispose of their own dead? If so, how and why? I would've though it would be much better to just eat their own dead, which would be a "free" food source allowing the colony to reclaim some protein and nutrients. It would cost much more energy (and risk) to transport dead ant carcasses away from the hive.


texts: Could below zero decibel environment cause arrhythmia?

texts:
While this topic has virtually no real life application and has never been examined due to obvious reasons, it is quite intriguing to me.

I've read a lot of speculations and claims about the world's quietest room (-8.7 decibel at Orfield Laboratories in South Mineapolis) including loss/deterioration of hearing, hallucinations etc. What I was wondering about is if any of the human self-preservance reflexes would kick in once an individual hears his own bodily fluids and organs expanding/retracting? Since, as far as I know, there aren't any scientific proofs or thesis on this subject, what are your thoughts based on your knowledge on regular body functions and reflexes?

Third-party links: TheDailySwarm's post, CBC's post, Quora's post


texts: How to identify Ag nanoparticles in a solution?

texts:
Doing an experiment involving the production of Silver nanoparticles using bacterial extracts. The issue is proving that they've been formed.
AgNO3 is added to the solution, and the reduction environment of the bacteria reduces into silver nanoparticles of various size, depending on many factors.
Color change can be seen, and a change in the UV-vis spec also, but beyond that, is there anything else that can be done?
The papers I'm basing this project off of have access to electron microscopes, I don't.
Is there any sort of biological assays that react to metallic silver? or maybe to Ag NPs?
Or anyone have any experience involving biologically producing nanoparticles?
I'll be asking in Chemistry as well for a possible chemical reaction of identify metallic silver.


texts: What is the probe that absorbs at 450nm in the presence of NADH in this assay?

texts:
The colorimetric assays by Biovision and Sigma Aldrich seem to utilise a probe that binds to or reacts with NADH in order to cause absorbance at 450nm which can then be quantified by a spectrophotometer.

What is the chemical basis of this reaction?


texts:
I watched the documentary "Evolve" recently and in the segment on "size" Scott V. Edwards, Harvard evolutionary biologist mentioned the idea that humans might evolve to be 7' tall in 'hundreds of years'. (I think this may have been taken out of context... I have emailed him to find out, but do not expect a response from someone so busy)

The reasoning goes that the trend in the past 100 years has been greater height, and women show a strong preference for men who are taller than they are. (Though a large share perhaps all of this difference has been due to diets higher in protein at an early age)

I wonder, though, if this is only part of the story. The preference women have is not just for tall men, but for a man who is taller than she is. Likewise, men seem to prefer woman who are shorter than they are. There is even cultural pressure: the classic western image of a couple on wedding cake always shows a man who is about 4" (to scale) taller than the bride.

Thus, women who are short have an advantage as they have a greater pool of men to choose from. (Colloquially, simply ask any 6' tall woman if she feels her height helps her find dates.)

Let's say that men seek women who are shorter than they are, but no more than 8" shorter. Women seek men who are taller than they are but no more than 8" taller. Given that the current average height for men is 5'8" and for women it is 5'4" (and distributed normally SD 2.8") will we have selective pressure that leads to greater or lesser height? (This is, obviously, oversimplified, but it is a starting point.)


texts: Can someone identify the species of this angiosperm?

texts: It seems to be from the pea family (Fabaceae) due to the zygomorphic flowers and the pods. It also has stipules at the base of the composite leaves. It's quite high (~ 80 cm). Photographed in spring in Morocco. It was photographed in a dry riverbed.


texts: How Do Pressure and Temperature affect arthritis?

texts:
Here, in Houston Texas we were hit by a cold front tonight and I remembered the old saying that I'm sure you've all heard "My joints hurt, must be a storm (or change in weather) coming in". It piqued my curiosity as I wasn't sure if it was due to the temperature itself or the atmospheric pressure difference causing the flare up of pain. I looked into it and, as far as I can tell from what I've read, scientists are unable to agree on what exactly causes the flareup of pain as the evidence from the myriad of studies done on the subject are inconclusive and different in each situation. The evidence being that both temperature and atmospheric pressure changes have shown to affect flare ups in joint pain due to arthritis as well as the opposite. It almost seems like all of it can affect arthritis pain, as well as none of it. However, I began to think "What if it has nothing to do with how much the atmospheric pressure or temperature changed, or in which direction they changed? What if it's simply due to change itself?"

My source: https://www.amjmed.com/article/S0002-9343%2806%2901026-6/pdf
The article expresses that temperature drops cause pain. However, it also states that the reasons for why this occurs is unknown. I also believe temperature raises may cause this as well as I myself, along with others I've talked to with arthritis, have felt that arthritic ache in both increases and decreases of temperature. I am posting this question because I have learned that temperature is unrelated to atmospheric pressurization as both high and low temperature air may have either high or low pressures.

I'm no expert in any of the scientific fields that are involved in this question. So, what do you as the community of StackExchange Biology think?

Bonus source from SE Physics for those of you unfamiliar with temperature and atmospheric pressure: https://physics.stackexchange.com/questions/326315/does-hot-air-have-high-pressure-and-does-compreesed-air-have-high-pressure/471775?newreg=ef5c317e3a114a3d8e4bb5fb680c477e


texts:
Wikipedia says:

  Leukemia inhibitory factor, or LIF, is an interleukin 6 class cytokine that affects cell growth by inhibiting differentiation.

So does this means that il6=LIF ? or does it implies that both il6 and LIF belong to some common class of cytokines?  If latter is true then what is the name of that class?


texts: What is this crow eating, and is it a common part of the corvid diet?

texts:
Here's a picture (by Rob Curtis) of a crow carrying and eating the corpse of what looks a bit like a small hawk or falcon:

Other pictures clearly show the crow is eating the dead bird. This image shows the underside of the head and beak; this one shows its legs, which are grayish.

What bird is being eaten?
Is this bird a usual part of the corvid diet? Or did the crow just opportunistically scavenge a dead bird?


texts: The biology behind tree pruning and hedge trimming

texts:
I read two contradictory arguments which both seem logical to me, related to the tree pruning and hedge trimming:

You should prune/cut trees only outside the growing season, when the tree is "sleeping". In some countries there is even a law forbidding to cut/prune trees within the growing season!
You should trim the hedges only within the growing seasons, when the tree is not sleeping and thus able to heal the cuts.

Which of these two arguments is true and how are they supported by the plant biology?


texts: why a testosterone pill can't be effective?

texts:
Why estrogen, progesterone etc. in the contraceptive pills survive the acid environment of the stomach and all the digestive enzymes, while testosterone needs to be injected or spread with a gel on skin?
I have no idea of why this difference in assumption, because I know testosterone and "feminine" hormones have the same steroid based structure...so I can't pick up why testosterone differently from "feminine" hormones can't resist the digestion.


texts:
In the Wikipedia article on dendritic spikes I read:

  In the hippocampus, the CA1 neurons contain two distinctive regions
  that receive excitatory synaptic inputs: the perforant path (PP)
  through the apical dendritic tuft (500-750 μm from soma) and the
  Schaffer-collateral (SC) through the basal and apical dendrites
  (250-500 μm from soma).

I wonder how the distinctiveness of these two regions does appear when plotting the number of synapses as a function of the distance to the soma:

More like the gray, or more like the red, or more like the green curve? Or which other?


texts: What are the uses of Helical Wheel Projections in Structural Biology?

texts: I have seen helical wheel projections used to illustrate amphipathic helices in proteins.  Are there any other uses for these models?


texts: Glucose Oxidase, Condition to be Active?

texts:
I most recently was reading/watching information on honeys antibatical and antimicrobial properties.  The enzyme Glucose Oxidase came up often as a main antimicrobial, yet it is inactive in honey.  How much would honey need to be diluted to make this enyzme active? I may potentially use honey in a dilute for as a backpacking emergency antibiotic/antimicrobial and/or something to irrigate wounds if severe.

I do have an basic (High School) understanding of chemistry if that helps


texts: Why does polyploidy give an evolutionary advantage?

texts:
I would like to know what advantages polyploidy holds. I have come across a few examples during my research of polyploidy, for example human adults' hearts contain 27% diploid, 71% tetraploid and 2% octaploid nuclei, Deinococcus radiodurans can have up to 10 copies of genome, and most of the plants consumed by humans have more than 2 copies.

I have no source of any sort for these, but I think they could be advantages:

One of the most obvious one would be resistance to more physical effects.
In the case of plants it might be the increased need for protein construction during the development of the seed.

What I would like to ask is whether the ones I wrote are correct, and if there are any other possible advantage.

I have read similar questions but could not find what I was looking for.


texts: What decides whether a lysogenic cycle or a lytic cycle will take place?

texts: A virus can either participate in a lysogenic cycle or a lytic cycle. What decides that?


texts: What physical or mental actions can be picked up by EEGs?

texts:
There certainly seem to be a lot of gadgets and gizmos leveraging EEG technologies to the control of devices.

This makes me wonder: what intentions/thoughts can be captured by EEG technology, and which ones can't?

For example: how about motor movements? If I am wearing one of these EEG devices, and I shake one of my fingers back and forth, is my brain generating waves that the EEG device will detect? Why/why not?


texts:
This page says it won't.

This page says it's the carb again http://www.mindbodygreen.com/0-10454/in-defense-of-bacon-why-eating-fat-can-help-you-get-thin.html

I don't see how eating fat will not make me gain weight while eating carbohydrates will, since fat is made of, well, fat.

It says eating carbs will make us fat. How can this be? Is this true?


texts: Are wild cats the same species as house cats?

texts:
I thought that the definition of species is "can interbreed"

From Wikipedia:

  The wildcat (Felis silvestris) is a small cat found throughout most of
  Africa, Europe, and southwest and central Asia into India, China, and
  Mongolia. Because of its wide range, it is classed by the IUCN as
  Least Concern. However, crossbreeding with housecats is extensive and
  has occurred throughout almost the entirety of the species' range.[2]

So why does it have a different name than the house cat?

From Species at Wikipedia:

  A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, the difficulty of defining species is known as the species problem.

While I understand that sometimes problems arise, what makes biologist mark the wild cat as a distinct species from the house cat? If they are genetically different, how different?

Donkeys can breed with horses. The result is sterile. Tigers can breed with lions with lots of complication. Wildcat seems to interbreed with housecat without problem whatsoever. Or does it? That's actually the essence of the question.


texts: Are there any examples of biological Turing machines? And what can they do?


texts: What fraction of bacterial proteins are membrane bound?

texts:
Almen et al. showed that around 27% of the human coding proteins are membrane bound.
How does this compare with bacteria such as E.coli or B.subtilis (or any other bacteria)? Is there a paper out there demonstrating this?
I assume that there would be massive variation among bacteria, so although one specific example would be enough as a ballpark, I expect that this may not represent all bacteria well.


texts: Determination of animal and vegetal pole

texts:
How do we determine which is an animal pole and which is a vegetal pole in a zygote?

My professor said that the zygote can be divided into two hemispheres, vegetal and animal poles. The hemisphere with yolk is the vegetal pole and the one without is the animal pole.

But I couldn't find an authentic book that I have access to saying anything about the polarity of the zygote. However I stumbled upon this paragraph from Objective Zoology and I'm not sure if it's right.

  Zygote or egg of frog is spherical and measures about 1.6mm in diameter. The upper half of the zygote is black (pigmented) and contains nucleus and cytoplasm. The lower part of the zygote is white or light yellow in colour and contains the reserve food in the form of yolk. The upper pigmented part is called the animal pole and the lower part vegetal pole.


texts:
From here:

Effect of temperature. Sperm cells will not mature at core body temperature in most mammals (spermatogenic DNA polymerase b and recombinase activities exhibit unique temperature optima); to adapt, the testes assume an external position. Testicular descent from the abdomen normally transpires during fetal or neonatal life.
If the testes fail to descend into the scrotum, a condition called cryptorchidism, the male will be sterile; gone uncorrected (by surgery or androgen treatment) spermatogonia will eventually degenerate.

How many minutes of exposure to hot water is tolerable?
Can regularly bathing in hot water lead to infertility?
Up to what temperature (of bath water - assuming the maximum tolerable temperature would not hurt skin) is tolerable?


texts:
I'm hoping for some information relating to yeast nutrition (specifically Saccharomyces cerevisea) in beer fermentation.

Zinc is well-known to be necessary for yeast cultures to perform successful fermentations and since fermentable sugars derived from barley are often deficient in zinc, they are sometimes fortified with additions of zinc sulfate or zinc chloride. This guy tried zinc gluconate, a readily available dietary supplement for the same purpose, and found it to have very little, if any, positive effect on fermentation performance. As he even suggests at the end of his paper, could this be because yeast can't assimilate Zn from this molecule the same way it does from the other two?

Is this question better directed towards Chemistry SE?

Thanks in advance for any help I can get on this.


texts:
Would anyone know how to go about obtaining samples of Salmonella or E. coli for purely educational purposes?

Note: I just want to look at the stuff under a microscope.


texts: What are some good biological tests you can do to yourself?

texts:
I would like to do things like study my own blood and DNA. What kind of things can one do at the present time that are fairly simple. Or require minimal equipment like a microscope?

Are there some genetic diseases or predispositions that one can do self tests?

I mean there are a few tests I know of that are very simple, like measure your own heartbeat or eyesight. But these are a bit too easy.


texts: how body doesn't make antibodies against adjuvants of vaccine?

texts: we know that all antigenic molecules don't have PRR on phagocytes and so they use an adjuvant that has a receptor for pattern recognation and fuse it with in order to phagocyte the antigen-adjuvant complex and present it on MHC II molecules for antibody syntheses now the question arises the phagocytes don't know which molecule is antigen and which is adjuvant then why MHC II molecules don't present the adjuvants for antibody syntheses and make the body sensitive against adjuvant and future vaccination should not be successful because the antibody recognises the adjuvant binds with it and not letting the vaccine to be processed?


texts: Why do OX5034 GM mosquitos require the presence of tetracycline to survive? What does the drug do in this case?

texts:
I'm confused. Debug Fresno; why are the released mosquitos said to be sterile? from 2017 addresses male mosquitos released with a bacteria that will affect fertility of females after mating. They are not genetically modified.
CNN's 2021 article First-ever US release of genetically modified mosquitoes begins in Florida Keys describes release of Oxitec's OX5034 GM mosquito Aedes aegypti. Curiously, these can be kept viable for reproduction when maintained in an environment that includes tetracyline, an antibiotic.
Question: Without the bacterial infection, is it just a coincidence that the GM strain needs an antibiotic to survive? What does the tetracycline do in this case? Why was this drug chosen?
Potentially helpful resources:

https://www.oxitec.com/en/our-technology
https://endmalaria.org/sites/default/files/Enca%20Martin-Rendon.pdf


texts: Can we change the Eye/Hair color by knocking out the OCA2, HERC2 and MC1R genes using CRISPR in an adult human?

texts:
This paper seems to describe the use of a plasmid delivered by a gene gun to depigment rat skin;

https://www.nature.com/articles/3302264
Published: 27 May 2004
Seeing the gene therapy: application of gene gun technique to transfect and decolour pigmented rat skin with human agouti signalling protein cDNA

Could a similar technique using CRISPR and chitosan change the eye and hair color of an an adult?


texts: How many teeth can "African wild dogs" have?

texts:
The New York Times article In Mozambique, a Living Laboratory for Nature’s Renewal discusses reintroduction of what the article calls only "African wild dogs" into Gorongosa National Park in Mozambique.

I was taken aback by the "smile" of one of the dogs shown below. Though I'm not particularly familiar with canine dental situations, this looks like an awfully large number of teeth. Is there a known limit to the number of teeth wild African dogs (or any canine) can have?

above: "A wild dog in Gorongosa. One pack has been reintroduced, and a second will be brought in next year.CreditBrett Kuxhausen/Gorongosa Media, via Associated Press" Cropped, from NYTimes.

above: "Wild dogs, apex predators missing from Gorongosa National Park for decades, have been reintroduced and are slowly making a comeback, part of an ongoing experiment in reviving the park ecosystem after years of devastating war.CreditBrett Kuxhausen/Gorongosa Media, via Associated Press" From NYTimes.


texts: Deciding a reasonable threshold for copy number variation in a CNV (SNP array) TCGA dataset

texts:
Is there a methodology to select a reasonable threshold for copy number variation in a CNV (SNP array) TCGA dataset, to define when there is a significative alteration?

Can I download CNV data for normal samples and take the 95th percentile of distribution? Are there better methods?

Update

This is the percentiles plot of the two distribution (Tumor vs Normal) of values, for the same technology (SNP array) and the same genome (hg19).

The tumor distribution has slightly more extreme values, though it is not enough in my opinion. For this reason I think I should not use a percentile score (the 5th and the 95th percentile of the normal samples distribution, for instance) to define the thresholds to call CNV alterations in the tumor samples.


texts: Where are action potentials initially created?

texts:
Is the axon hillock still the place where one thinks and talks of that action potentials are initially created? (I've heard this place moved into the direction of the axon initial segment.)

If one doesn't want to commit oneself whether it's the axon hillock or the initial segment where action potentials are initially created – because it's somewhere inbetween or at both of them, or it depends on the type of neuron, or we don't know, or we don't care:

  How does one talk about that place unequivocally?

Is there an abstract (non-anatomical) terminus technicus for "the place where action potentials are initially created"?


texts:
As blunt as possible: when performing real time PCR it is a routine step to run one PCR in order to plot a "standard curve" with several decreasing dilution ratios from your sample. what is the real purpose of this?
how should results be used/interpreted?


texts: Will charged water ions sprayed onto plants keep insects off?

texts:
I had stumbled on an article about a Dutch firm that devised an irrigation system that used mist of ionized water droplets that they claim keeps insects away from the plants.  This break through would revolutionize eco-friendly organic agriculture by reducing the need for insecticides.  They also claim nitrates are also formed by the process and embedded in the mist to supply nitrate fertilizers as well.  Thus eliminating the need for extra chemical fertilizers.

I tried to find the site again and the company but not coming up on search.
Are there any merits to these claims?  How would such a process or device work?


texts: What is the process of degradation of proteins into amino acids inside living cells?

texts: Just like beta oxidation does our cells have a distinct mechanism for degradation of proteins? There are processes for degradation of amino acids but where does these amino acids come from, is it all from dietary proteins? Are they not obtained from the proteins(enzymes) that are being continuously made inside the cells?


texts:
Viruses are created in their fully-formed state and do not grow. But one thing has been bugging me lately:
can a virus be deformed, e.g. in order to fit into an opening slightly smaller than itself? Say you were to apply a force to the virus perpendicular to the smaller hole; would the virus merely break, or is it possible for it to deform and retain its structure on the other side?


texts: Comparison of examples in incomplete dominance and Co dominance

texts:
When we consider examples of incomplete dominance we take that of FOUR O CLOCK plant -

We say that alleles for red and white colour of flower are not completely dominant against each other. Hence in hybrid progeny we
Say (as in standard textbooks) that pink colour appears due to "expression of single gene for pigmented flower which produces only pink colour (quantitative inheritance )"

In codominance concept we take example of SHORT HORNED CATTLE which again appears as same case white and red cattle produces roan coloured hybrid progeny but due to "juxtaposition of small patches of red and white colour hair"

The same principle can be applied to four o clock plant too. Suppose pink colour of flower is too due to juxtaposition of red and white coloured elements.

Then where is the difference between the two concepts?

Further the thing which puzzled me more was that - "initially cattle example was considered to be in complete dominance. Later it was CORRECTED to codominance "
Also incomplete dominance is also known as "mosaic dominance" but actually mosaic happens in codominance.
Kindly clarify my doubts


texts: What happens to Mean systemic pressure during the start of aerobic exercise?

texts:
Hi this was one of the answers to a MCQ I had to do (it said it would decrease 2 times in the first 10 seconds of a run). I am not too sure what actually happens to it though
Using the equation VR=MSP-RAP I assume MSP would increase due to an increase in VR but I am not too sure
Thank you!


texts: constitution of read and gene region (IGV)

texts:
I work with fastq files containing NGS reads for some human DNA regions. The reference genome is hg19. I had two fastq files (pair-ended). I generated alignment BAM files. I used "bwa" and samtools to find a possible target gene region (chr7:55,242,376-55,242,574,). This corresponds to a region of the EGFR gene.

Here is a screenshot of the gene region

And here is a screenshot of the primer region

I also have a list of primers and reverse primers:

FORWARD
1. TTGCCAGTTAACGTCTTCCTTCTCTCTCTG
2. CCCTTGTCTCTGTGTTCTTGTCCCCCCCA
3. TGATCTGTCCCTCACAGCAGGGTCTTCTCT
4. CACACTGACGTGCCTCTCCCTCCCTCCA

REVERSE
1. GAGAAAAGGTGGGCCTGAGGTTCAGAGCCA
2. CCCCACCAGACCATGAGAGGCCCTGCGGCC
3. TGACCTAAAGCCACCTCCTTA
4. CCGTATCTCCCTTCCCTGATTA

And I have some adaptors

ADAPTORS 1
AAGACTCGGCAGCATCTCCA

ADAPTORS 2
GCGATCGTCACTGTTCTCCA

I have to answer to the following questions:

1) What is the constitution of each read (adaptor+primer+amplified region)?
The forward primer is obvious and corresponds to the first primer of the list

TTGCCAGTTAACGTCTTCCTTCTCTCTCTG

So why do we have the three other forward primers? I don't understand. And what about the correct reverse primer?

It seems to be the complementary sequence of the end region

GAGAAAAGGTGGGCCTGAGGTTCAGAGCCA

Finally which adaptor is used?

Is [ADAPTOR1 - PRIMER1 - AMPLIFIED REGION] the correct answer? Are there other possibilities?

2) % of reads that map the human genome? what about the unmapped?

Can you please give me some clues about how to answer this question.

I just need some clues I want to do it by myself.

Thank you very much for your help.


texts: Can nitrate be an electron acceptor for NADH generated in the citric acid cycle?

texts: Is the citric acid cycle aerobic or anaerobic? I know that the oxygen is required to accept the NADH electrons so that NAD+ could be regenerated. Nevertheless, if other electron acceptors, as nitrate (NO3–), are present, could they also be used to regenerate the NAD+? I am asking this because I read a thesis claiming that “acetly-CoA enters the citric acid cycle and through anaerobic nitrate-respiration a multiple amount of ATP is generated.” If you have some literature that you can share with me I would be really grateful. Thanks.


texts: Can anyone point me toward a computationally-accessible database of medical assertions? I'm looking for something where each row in the database contains a single unit of knowledge. It could either be in some sort of structured format, or be in free text.


texts: I know there is a difference between digestive and metabolic waste, but which one is called excretion? And what's the other one called? Thanks!


texts: Is a "Fact" any theory for which there is overwhelming evidence in any field other than biology?

texts:
Evolution is often described as a fact, and a theory. Evolution is a heavily overloaded term, with one definition being the fact that, "changes in the frequency of alleles in populations of organisms from generation to generation." This is a measurable fact, but not the usage of the word evolution that I am in interested in.
Wikipedia has several quotes on the matter, including the Webaters definition used in this questions title, but also includes clearly observational facts like the Earth revolves around the sun.

A fact is a hypothesis that is so firmly supported by evidence that we assume it is true, and act as if it were true. —Douglas Futuyma
There is no sharp line between speculation, hypothesis, theory, principle, and fact, but only a difference along a sliding scale, in the degree of probability of the idea. When we say a thing is a fact, then, we only mean that its probability is an extremely high one: so high that we are not bothered by doubt about it and are ready to act accordingly. Now in this use of the term fact, the only proper one, evolution is a fact. —H. J. Muller
Scientists most often use the word "fact" to describe an observation. But scientists can also use fact to mean something that has been tested or observed so many times that there is no longer a compelling reason to keep testing or looking for examples. The occurrence of evolution in this sense is fact. Scientists no longer question whether descent with modification occurred because the evidence is so strong. —National Academy of Science

Do scientists refer to any theories for which there is overwhelming evidence as a "scientific fact", other than in biological sciences?
Note: Good answers will include quotes from scientific organizations or prominent scientists using the term fact to describe the theory, and will include references to the theory itself.


texts:
I see that cyanocobalamin is not naturally occurring, and is synthesized in vivo to methylcobalamin. As part of the synthetic pathway, cyanide is broken off. All opinions I can find are that this isn't a problem as cyanide is naturally occurring in many foods anyway, and is safely detoxified via the the Rhodenase pathway.

However, given its synthetic creation and vast prevalence as the primary B12 source in nearly all supplements, I was curious if any actual studies did exist to rule out potential (albeit minor) long term cyanide toxicity for this synthetic form of B12. I'm unable to find a single study where cyanide toxicity  was directly tested for, only studies stating that RDA in excess of 1000 times the daily dosage isn't lethal.

I understand no evidence currently exists for cyanocobalamin toxicity, but this wouldn't be surprising if there aren't any studies done in the first place.

Would anyone be able to reference an actual study that directly measured levels of potential cyanide toxicity for cyanocobalamin in any animal or humans?


texts:
Today after cutting open a papaya , a plant was found in it:

How is it possible for a plant to grow in a fruit? How does it gets $CO_2$ and light for photosynthesis?


texts: Genomic location-coordinate of RdRp of SARS-CoV2

texts:
I understand that nsp12 is the RdRp protein in the ORF1 of SARS-CoV2 genome. And nsp12 starts from the starting nucleotide base of orf1ab. Could you please tell me the exact genomic location coordinate of RdRp?

Is there and database from where the FASTA sequence (nucleotide and aa) of RdRp of SARS-CoV2 can be obtained?

Any answer to this question would be highly appreciated.


texts: How does glucose delivered intraperitoneal (i.p.) get into the peripheral circulation?

texts:
Intraperitoneal delivery of drugs or fluids is something that occurs much more frequently in veterinary medicine than clinical medicine. In veterinary medicine or scientific studies using animals, compounds are frequently given via this route that it is typically referred to as "i.p. injection" or "i.p. delivery".

When glucose is delivered via this route (by injection or catheter directly into the peritoneal space), how does the glucose actually get into the systemic circulation? That is, where does it actually go anatomically?

I can't find much data on this or an explanation that is collectively agreed upon. In particular for drug studies, some people say that the drugs or metabolites get into the portal circulation of the liver, while other people say that the drugs are absorbed by the peritoneum and enter the systemic circulation via the lymphatic system? Some individuals would argue that substances diffuse across the peritoneal membrane and then make their way into the interstitial fluid first, and then passively diffuse into the body's fluid compartments. Could it be another route? Could it be an active process or is it completely passive? Or, alternatively, could it be a combination of several of these processes?


texts: Can a cell survive temporarily without oxygen?

texts: Can temporary denial of oxygen to a cell damage the cell? Will the cell continue to live in partially damaged condition if the supply of oxygen and nutrients are restored?


texts: Constantly wiggling moth pupa - will it emerge soon?

texts:
Today I found a moth pupa in the soil in my garden in western Sweden. It's about 15 mm long.
I have found similar ones before, but this one is wiggling a lot more, even after I put it down and put a bit of dirt over it. It's been moving for more than an hour now, but less now than in the beginning.

I was hoping to see it emerge, but if it will take more than a day or so, I will probably put it back. So, what I'm wondering is if this wiggling is any indication of how soon it will emerge. Or if there are other ways to tell.

Update: an hour later it has stopped moving. Maybe it was just very disturbed by my presence. I'm keeping it in a jar with soil and a stick for climbing up on, and I'll decide what to do with it tomorrow.

Update: 12 hours later and it seems very still. But I'm letting the question remain since I really want to know if there are any signs to look for.

Final update: After 16 days it had turned almost black, and was still very active when handled.

And after 17 days this moth came out:


texts:
I am wondering how we perceive color and whether that is dependent on the wavelength of the light, or on something manufactured in the brain.

For instance, if we evolved on a planet orbiting a red dwarf star, would we see colors differently than we do now, given that our sunlight has another wavelength composition?

I know that there have been experiments where volunteers have worn glasses that make them see the world upside-down and eventually the brain corrects this and they see right-side-up again (and have to re-adapt when removing the glasses). I wonder if something similar would happen with color perception.

Does anyone know of any studies done that have tested this?


texts: How do photoreceptors overcome the ambiguity of wavelength vs intensity to determine brightness?

texts:
I asked a similar question about the Principle of Univariance yesterday, but now I have another one.

According to the Principle of Univariance, the input to a photoreceptor differs along two dimensions (wavelength and intensity) but the output can only vary along one dimension (the cell's graded potential).

This means that there is inherent ambiguity in the output of the photoreceptor. What I do not understand then is how it is possible for a rod (or cone) to ever distinguish between intensities (or wavelengths) when each photopigment can absorb a range of wavelengths at different probabilities.

For example, say a rod cell absorbs $50\%$ of all photons at wavelength $x$ and $25\%$ at wavelength $y$.
If 100 photons reach the rod cell at wavelength $x$ we can roughly assume that $100*0.5=50$ isomerizations will occur. Equally, if 200 photons reach the rod cell at wavelength $y$ then we can roughly assume that $200*0.25=50$ isomerizations will also occur. From the perspective of the cell's synaptic activity, the two responses will be the same despite the large difference in intensity.

Clearly there are an infinite number of permutations to this basic pattern. It is thus unclear to me how the visual system is able to obtain any information about the intensity of light in rod cells.

The same issue also appears present to me in cone cells (the usual explanation is that the relative amount of excitation/inhibition can be compared between cone cells, but this does not seem to solve my overall question).


texts: This strange spiral creature grew up in my cup of water after night

texts:
This grew up in my water cup over night!

Length ~ 12mm
Form - spiral made of dark dots
It does not move
Growing slowly

Can some one help identify it?


texts: What is the timing of information assimilation within a human brain?

texts:
A little background: I'm an avid dreamer and have great dream recall, sometimes up to 5-7 per night.

In my experience, I can sometimes trace some elements of the dream to an event that occured within a 1-3 day window prior to the dream.

I've done similar experiments with the process of idea generation, where an idea that I have can be traced to experiences from the previous 1-3 days.

This makes me interested if there have been some kind of studies on how rapidly the brain absorbs and assimilates information from short term memory over to the long term memory. Has there been any studies on how long the brain keeps information before discarding or processing/assimilating it into dreams or new ideas?


texts: My BRIG run is suspiciously quick. What is a typical length of time for a run?

texts:
I use the BRIG (BLAST Ring Image Generator) program to compare prokaryote genomes. It executes a local BLAST+ and visualizes the results as rings around the reference genome. I downloaded three genomes (~5 million to ~5.5 million base pairs long) from the NCBI to test the application with. It only took 5 to 10 minutes for BRIG to finish. In my personal experience, BLAST is never that fast. Certainly not while comparing entire genomes. I'm also quite sure my computer is not thát fast and changing BLAST parameters doesn't do much difference. The output appears to be good however.

Is my input just small, is my PC better than I know or is it something I'm not aware of?

What would be  a typical time for a run of that magnitude?

Sources:
Website BRIG
Genomes used:

Accession: BA000007.2 GI: 47118301
Accession: AE006468.2 GI: 973795115
Accession: AL513382.1 GI: 30407157


texts: Difference in rose seedlings with red or green seed leaves

texts:
I tried to sowing roses from rose hips the first time. (In autumn I collected some rose hips random from different bushes in the neighborhood. I mixed the seeds while sowing.) Now the seedlings grow one after another. Thereby I noticed, that some have their first leaves in a more red color, and others in a clear green.
Could I conclude some characteristics of the grown up plant out of this?
(I tried to search for "roses red or green leaves" but only get an amount of results with red petals...)


texts: What's the evolutionary reason behind feeling 'sorrow'?

texts: As it's established that life's design is a product of evolution, what advantage does emotions like sadness play in the life of an individual/species ?


texts: What are current abiogenesis hypotheses for first food source?

texts: What is the very first abiogenetic piece of reproducing life (small piece of RNA + ribosome that randomly occurred?) hypothesized to have used as an energy source? I'd be interested in sources to what experts in abiogenesis research have hypothesized on this subject, if any such researchers have spoken on the question.


texts: What factors affect the number of individuals in an animal group?

texts:
Social animals can live in groups whose numbers vary greatly according to species (for instance wolves vs deer herds vs buffalo stampedes vs lemmings).

Is this number regulated only by environmental factors (resource abundance, position in the food web etc) or is there a genetic upper bound to this number which prevents overcrowding? Put in other words, would a species with endless food resources (but finite space) grow endlessly?

If the genetic regulation is common, then why humans don't seem to be subject to it?


texts: COPI/COPII proteins and kinesins/dyneins

texts:
I am considering the transport of protein from ER to Golgi, and have read that this involves the COPII protein coat. I have also read that this is a form of anterograde transport, and elsewhere that kinesins are responsible for anterograde transport as they move from the negative to positive  (outside) poles of the microtubules.

Thus it seemed to me that the kjnesins carry the COPII vesicles carrying proteins from ER to Golgi.

However a Google search of the terms 'kinesins' and 'COPII' together did not seem to yield anything about kinesins carrying COPII.

On the other hand in this article it links COPII with dynsctjn, which I have not heard of before.

Does someone know the link between COPI and COPII transport, and/or retrograde and anterograde transport, with the microtubule motor proteins kinesin and dynein? Where do dynectins come into this? Do they bind the vesicle to the dynein or are they a different type of motor protein? If it is the first case, then why is this transport termed anterograde if it does not use kinesins? Are the terms anterograde and retrograde not directly related to kinesin/dyneins use?


texts: What keeps the resting potential of neurons constant at -70 mV?

texts:
I know the sodium-potassium pump pumps out 3 Na+ ions and pumps in 2 K+ ions per reaction so the negative charge in the axon increases. However, once the voltage (difference of charge inside and outside of the neuron) gets down to -70 mV, this stops going further below. Why?

I know that this is because of other transport proteins and the presence of anions and cations in the axon, but what are those proteins and ions precisely? There are always negatively charged proteins inside a cell, including a neuron, so I assume there must be a strong force which keeps the voltage from going down.

By the way, is the opening and closing of an ion channel triggered by the voltage of the neuron or the concentration of the ion?


texts:
1.) How many versions (alleles) of a gene can we carry if every chromosome is in pair?

2) What happens during the gamete formation (meiosis) ? Do the gene pairs stay together?

3) What happens then to the paternal and maternal sets of genes that we inherited ?

My attempts

1) I think that it could be any number, but confused with 2 as an answer.

2) Gene pairs must refer to homologous chromosome pairs which remain together in meiosis-I and get separated in meiosis-II. So in net process, it get separated.

3) It is used for producing proteins essential for body functioning by the process of transcription and translation. These genes with some changes (due to crossover) will also be transferred to second generation.


texts: What determines the strength of a tree. A morphologically strong looking tree found broken down at trunk. can we determine the strength/ life of a plant


texts: Can genes that activate transcription factors also called be called transcription factors?

texts: If the sole known function of a gene is to activate a transcription factor, would that gene also be considered a transcription factor, or is there a word for such genes that are further upstream on the transcription activation cascade?


texts: Lifeforms concentrations of the categories of macromolecules, and Lipids

texts:
Lifeforms are formed of large, modular, organic molecules called macromolecules, large organic molecules called Lipids, and simpler molecules such as H2O.

Macromolecules are commonly grouped into the following categorises:

Protien
Nucleic Acid
Carbohydrate

The concentrations of these types of molecule by mass, in a dehydrated (therefore dead) "E. coli" are:

Protein: 55%
Nucleic Acid: 23%
Carbohydrate: 0%
Lipid: 9%

From: http://book.bionumbers.org/what-is-the-macromolecular-composition-of-the-cell

Q: Repeating the above table for other lifeforms, for the whole organism if it is multi-cellular, can examples be given of lifeforms that are particular outliers?

I have been unable to find much more useful information, however this data probably exists, I could find nothing for larger lifeforms such an animals. Around 60% of a cells cytosol is proteins, however this is by volume, not by mass.


texts:
I've been reading how some molds may be carcinogenic. In particular, molds associated with the fungus metabolite, Aflatoxin.

Are the types of mold that produce this toxin, present in buildings/showers/domestic environments, or do they only grow on food-stuffs?


texts: Does protein consist of repeating units of amino acids?

texts: I am currently studying the chapter called macromolecule. I get that a nucleic acid consists of repeating units of nucleotides, and I personally think "the repeating units" does not mean the nucleotdes are all the same, as nitrogen bases have four types either in DNA or RNA. How about the protein molecule. A protein molecule is made up of amino acids. However, I am sure about whether a protein molecule are made up of same and repeating units of amino acids. Theoretically, the R group in each protein is differed from one another. Therefore, does that mean we cannot state that a protein molecule is made up of repeating units of amino acids?


texts: Is there a protocol for freezing and thawing Bacillus subtilis cells?

texts:
There is a book that says to store Bacillus spores in 50% glycerol at -70 degrees Celsius (doesn't mention if the 50% is final concentration or not). But from what I know, the cells themselves can be stored in any % glycerol as long as the final glycerol concentration is 15% (v/v) at -80 degrees Celsius.

Is there a difference between preserving spores and cells? Because the book said to preserve the cells at a certain glycerol concentration and the spores at a different glycerol concentration.

Also, say I scrape some B. subtilis out from the cryovial for reuse, and they are frozen. Do I wait for the scraped cells to thaw and then plate them, or plate them while they are still frozen?

And if I want to sporulate these cells, should I recover these frozen cells by plating and incubating overnight, or can I just drop them directly into the sporulation medium? I want to get the details down properly.


texts:
A question that appeared on my last exam was :

  Which of the following has greater entropy A) An atom B) A
  macromolecule

The question doesn't specify anything else(i.e. type/size of atom or macromolecule). The macromolecules we learned class were proteins, sugars, nucleic acids(DNA/RNA) or lipids. What is the correct answer and why(hypothetical calculation, if possible) ?


texts: How does translation invariance in vision happen?

texts:
Convolutional neural networks are very popular these days in computer vision.  One of the things they do quite well is recognize objects with translation invariance.  The way they do this is by "tying together" the strengths of certain synapses, so that they all change in the same way during learning.  This is apparently not biologically plausible.

My question is this: what is known about how biological visual systems achieve translation invariance.  For example, how is it that if we learn to recognize a new object with our left eye, we are automatically also able to recognize it with our right eye.  What is the neuro-biological basis for this invariance?  My field is mathematics/machine learning, not biology, so I would appreciate responses that are not overly technical (although I understand that might not be possible).

Thanks!


texts: Can human pathogens present on plants become plant pathogens?

texts:
Since human pathogens sometimes live on the surface of plant leaves(read here and and here), and there are plant-pathogen microbes also living on leaf surfaces, is it possible for plant virulence genes to transfer to the human pathogens (perhaps via horizontal gene transfer) and make the human pathogen also pathogenic to plants? Has there ever been evidence of this happening?

This review paper addresses why plant pathogens haven't "crossed the Kingdom border" to being human pathogens, but what about the other way around (human pathogens affecting plants). Since there is such a wide array of plants out there with a wide range of pathogen interactions, it seems to me that it would be statistically more likely that a human pathogen could mutate to be pathogenic to some plant, than some plant pathogen could mutate to be pathogenic to specifically humans. Is that assumption valid? Also, I am talking about human-animals specifically, since it looks like there is a known virus infects both animal and plant cells in the lab (Lepidoptera/ cow pea)

As a currently-relevant example, could some plant virus, say Southern Bean Mosaic Virus, somehow share genes with a coronavirus strain and become a morph plant-human pathogen? (I know this last question is a little "out-there"). I chose that example plant virus since it is a positive-strand RNA virus like SARS-CoV-2. Thank you!


texts: where does genetic material for antibody production come from?

texts:
All antibodies are proteins and like every other protein, mRNA codes for them. So acquired immunity, is acquired, which means that information was not previously present in our DNA before exposure to the pathogens.

So my question is, does our DNA in some way get modified or something else? Where does the new genetic material come from?


texts: Why do so many parasites infect definitive and intermediate hosts rather than just one host?

texts:
Many parasites infect multiple host species, with one host species being the definitive host (where the parasite reproduces), and the other host species being the intermediate host (where the parasite grows to maturity). (Further details described as "complex life cycle" at https://en.wikipedia.org/wiki/Parasitic_life_cycle ) Why is this complex life cycle so common? Why wouldn't more parasites adopt a simpler life cycle of just one host?

I knew that there were some parasites that infected more than one kind of host species, but now that I am looking into it, it seems like a majority of internal parasites have this kind of life cycle. Does anyone know why?


texts: What causes paresthesia from compression?

texts: Compression of a nerve causes loss of afferent and efferent information in it. What is the physiological basis of this?


texts: Are Hsp70 proteins only activated in response to heat shock?

texts:
Hsp70 proteins are chaperones that assist in protein folding in my plant physiology textbook it says the Hsp70 proteins were discovered by inducing heat shock. But do they only work in response to heat shock stress?

I know these types of proteins are found in many organisms but I am interested in how they assist on protein folding or stress response in plants specifically.


texts:
If testing for bacteria (gram-negative) in a urine culture, are negative or positive cultures needed?

I could not find anything that says controls are needed unless results seem to be contaminated. I thought since controls are used in Gram stains, they would be used in cultures as well. Thanks!


texts:
I'm looking for the composition of the EZ-Vision DNA Dye for electrophoresis visualization. I could not find anything helpful on the web.

I would appreciate a lot your help :)


texts: Is there any technique can quickly expand one set of cell chromosomes?

texts:
Assume a cell type is very scarce while isolated out and hard to expand in vitro, and I wanna have more of its chromosomes, is there any technique , in vivo or in vitro or ex vitro, any would count, that allows me to quickly expand the amount of those chromosomes?

I know it sounds weird but just some curiosity~

Thanks


texts:
This may be anecdotal; please feel free to vote to close.

After staying awake for an extended duration, I usually find myself having to take extra effort to focus my eyes on an object. Similarly after exerting myself to the extent of near total exhaustion I find it necessary to consciously focus to perform actions that would otherwise require little conscious effort (E.g. Writing a note). There're other similar symptoms almost all of which mandate 'conscious effort'.

What really happens when a body is tired?
As a corollary, why does making conscious effort usually beat the initial error?


texts: What are the positive and negative effects of insulin on cognitive function?

texts:
A UCLA study seems to imply that insulin interferes with cognitive function.

  The DHA-deprived rats also developed signs of resistance to insulin, a
  hormone that controls blood sugar and regulates synaptic function in
  the brain. A closer look at the rats' brain tissue suggested that
  insulin had lost much of its power to influence the brain cells.

  "Because insulin can penetrate the blood–brain barrier, the hormone
  may signal neurons to trigger reactions that disrupt learning and
  cause memory loss," Gomez-Pinilla said.

  He suspects that fructose is the culprit behind the DHA-deficient
  rats' brain dysfunction. Eating too much fructose could block
  insulin's ability to regulate how cells use and store sugar for the
  energy required for processing thoughts and emotions.

  "Insulin is important in the body for controlling blood sugar, but it
  may play a different role in the brain, where insulin appears to
  disturb memory and learning," he said. "Our study shows that a
  high-fructose diet harms the brain as well as the body. This is
  something new."

At the same time, increased levels of IGF-1 seems to be implicated in higher level of intelligence. IGF-1 is not the same thing as insulin, but it does seem to have many similar effects.


texts: Can life subsist on anything else but water?

texts:
Inspired by an answer to a previous question.

It's hypothesized that extraterrestrial life could be based on silicon rather than carbon as its main structural element.

Are there similar theories about an alternative "life solvent" rather than water?


texts:
Fitness is certainly the most important concept in the theory of evolution. My question does not have to do with practical measures of fitness but with the theoretical definition of it.

I am a bit lost with the concept of fitness. Below I give some possible definitions of fitness and I am hoping to get critics for these definitions. The broad question is What is the definition of fitness?

In the following, to make things easier I will consider only one bi-allelic locus. For simplicity, I will assume a panmictic population of infinite size evenly distributed into age classes.

1) Let the variable $M$ be the mean time of a generation in the species of interest. Measure the allele frequency $p(t)$ and measure the frequency $p(t+M)$. By comparing the two you get the ratio of fitness of the two different genotypes. Obviously it does not work if we have sexual reproduction or diploid selection.

2) Genotype the individuals and wait until they die by counting the number of offspring they had and take the mean per genotype ($W_{AA}$, $W_{Aa}$, $W_{aa}$). This method would not work if they have different lifespan. One individual might make two babies in 8 years and the other would make two babies in 2 years but they would have he same fitness.

3) Do the same that at 2) but don't wait until they die, wait 1 month, Or 2 years?, or $M$?, or $2\cdot M$?, or...? What is the right decision? The more you wait, the closest you will be to the long term effect of natural selection. The less you wait, the more probable you will suffer of genetic drift.

4) Fitness is just a measure of natural selection that is not perfectly accurate because it is measured at short-term. In some circumstances, our measure on this short term is representative (Wright-Fisher equation) enough of what will happen on the long term.


texts: Why are vertebrae, specifically, so important in classification?

texts:
A fundamental level of animal classification is the distinction between vertebrates and invertebrates.  The vertebrata are, arguably, often classified as higher life forms than the invertebrata.  But why is the presence of the spine so important?  Why not use the simpler concept of internal bones as a classifier?

I might be missing something, but I can't think of any creature that has an endoskeleton but no spine.  Do any such creatures exist?  If not, why does classification focus on the spine and not the endoskeleton?


texts: Question about what the liver does NOT do

texts:
Which of the following functions is NOT performed by the liver?

a) Storage of vitamins and minerals
b) converts glucose to glycogen
c) converts toxins to harmless chemicals
d) produces bile

I chose b and got it wrong, any help?


texts: Is the fixation rate always equal to the mutation rate for neutral alleles?

texts:
Background

A classical result of population genetic is that the rate of fixation of netreual alleles is the mutation rate $\mu$. The reason is that each generation $PN_e\mu$ mutations enter the population, where $P$ is the ploidy number (e.g. 2 for diploids) and $N_e$ is the effective population size. The probability of each neutral mutation to reach fixation is simply its frequency $p$. When the mutation occur $p=\frac{1}{PN_e}$ and therefore the rate of fixation is:

$$\lambda = PN_e\mu \frac{1}{PN_e} = \mu$$

This result s typically very much used in phylogenetic, as assuming a constant mutation rate only, one can estimate the divergence time between two extant lineages.

The above is also explained on wiki>fixation_rate

Question

How robust is the result $\lambda = \mu$?

I understand that the result $\lambda=\mu$ is independent of the effective population size but is it also independent of..

changes in population size?
background selection?
selective sweep?
population structure?
selfing rate?
etc..


texts: Does this "fleeing spiders leaving fields of webs" phenomenon have a name?

texts:
I have recently seen images of big areas covered in spider webs:

After flood in Australia

http://news.nationalgeographic.com/news/2012/03/pictures/120307-spiderwebs-australia-floods-wagga-wagga-world-science/#/spider-webs-australia-floods-bush_49725_600x450.jpg
http://www.dailymail.co.uk/news/article-2111390/Australia-floods-Spiders-cover-fields-cobwebs-flee-rising-water.html
http://www.hoax-slayer.com/spider-fields-australian-floods.shtml
http://www.theatlantic.com/infocus/2012/03/spiders-flee-australian-flood/100265/
http://io9.com/5891091/massive-spiderwebs-engulf-australian-town-as-arachnids-escape-floods

I would like to read about this on wikipedia. So I am looking for a name of this phenomenon. Do you know how it is called?


texts: Why are transmembrane proteins difficult to crystallise?

texts:
I know that in vivo there are a lot fewer transmembranous proteins in general, and that they are produced at a lower rate than their free counterparts. This is mainly because transmembrane proteins are only required in a 2D space on the membrane rather than a 3D cytoplasmic or extracellular space. This (again, very broadly speaking) means that the probability they will interact with their target is higher.

I also know that this is one of the reasons that producing crystals for X-ray crystallography is notoriously difficult for transmembrane proteins. What are the other reasons that make transmembrane proteins typically tough crystallisation candidates?

What specific part of the crystallisation process yields such poor success rates of transmembrane protein structure elucidation?


texts: When does a chromatid become a chromosome?

texts: When chromosomes lie on the metaphase plate, they have the characteristic X shape. But these are actually two chromatids that are held together at the centromere. If separation fails and both chromatids are pulled in the same direction it leads to trisomy (three homologues chromosomes). So when exactly does a chromatid become a chromosome if it's not after successful separation?


texts: Which biosynthetic pathways take place in the plastid and were are they located?

texts: I know that the isoprenoid, jasmonate, glucosinolate, fatty acids, chlorophyll, starch, and aromatic amino acid syntheses are located in the plastid. But I don't know if they are located in the thylakoidlumen or in the stroma.


texts: Differences between comatosed states and brain death

texts:
What are the neurological, physical, etc. differences between someone who is in a coma (one that is not medically-induced) and someone who is colloquially deemed "brain dead" (being physically kept alive by machines)? Is there a certain minimal brain activity that is present in a comatosed state that is not present in brain death?
I found a decent definition here which defines the difference as:

Brain death: Irreversible cessation of all functions of the entire brain, including the brain stem. A person who is brain dead is dead, with no chance of revival
Coma: A state of profound unresponsiveness as a result of severe illness or brain injury

I can find other similar, vague definitions in a few other places.
I am wondering what is different about the neuronal structures or electrical activity between brain death and coma. Is there simply no (zero) neural/electrical activity with brain death, whereas there is with coma? What would be physiologically different with brain death that would prohibit such neuro-electrical activity?


texts:
I'm planning to start an artificial ant nest and I'd like to learn something about this specific species of ant that I captured in central Colorado.

Could you tell what kind of queen is that? Is there any image reference that would help me find out? Ideally with some location search possibility.


texts:
I found a commercial reagent called in vivo-jetPEI® from Polyplus-Transfection that is able to delivery mRNA in vivo. I'm planning to do an experiment with it, but I'm worry about how to synthesise mRNA and purify them clean enough to inject to living body.
I also found a recommended Kit called HiScribe T7 High Yield RNA Synthesis Kit that can help me to synthesise mRNA but I'm not sure if I can use the final product for an in vivo injection. Anyone have any experience with it?


texts: What would happen to a body in an astronaut suit over time if floating free?

texts: I'm not sure if this is best in Biology or Physics, but on Earth we decay to skeletons and then eventually to dust.  What would happen in space in a space suit?


texts: In this illustration about CRISPR function, what do these objects mean (image provided)?

texts:
In the paper on CRISPRs, the following figure is shown:

I added the light-green boxes.

What do the red arrows and the line with a filled circle on the far left mean?
What does the arrow in the middle mean (also just infront of cas9)?
Is the purple square to be understood as the RNA section in the B plot (blue arrow)?

Taken from here.

The caption is (cited):

  The type II-A system from S. pyogenes is shown as an example. (A) The
  cas gene operon with tracrRNA and the CRISPR array. (B) The natural
  pathway of antiviral defense involves association of Cas9 with the
  antirepeat-repeat RNA (tracrRNA:crRNA) duplexes, RNA co-processing by
  ribonuclease III, further trimming, R-loop formation, and target DNA
  cleavage. (C) Details of the natural DNA cleavage with the duplex
  tracrRNA:crRNA.


texts: Do dogs and cats know the names of other people / pets in the house?

texts:
I have a dog named Penny and a cat named Milo. I always wonder if Milo knows Penny's name, and vice versa. So if I call Penny, does Milo know that I just called her? Similarly for humans, if someone is over the house that they're familiar with, do they know that person's name? If someone calls me by name, do my pets know that I've been called?

What about other interactions - not just calling someone (scolding, feeding, asking to do a trick, etc).

I'm looking for a more scientific answer if possible - meaning studies and facts. I've had dogs all my life, and cats for the past 10+ years, so I know they're very smart. But I want more than just "I know my dog knows my cat's name, because she's just so smart". I'm wondering if anyone has ever studied this and proven it one way or the other.


texts:
Does freezing microorganisms such as probiotics kill them?  If not, what is the process that allows them to "come back to life" after the temperatures are increased?

As an example, lets say you freeze a yogurt (whether it be Greek, Australian, Turkish, Indian, Russian, European, or Western) and eat it while frozen.  Would the probiotics in the yogurt "come back to life" and be beneficial?

Specifically, I am referring to freezing refrigerated yogurts, and not products that are sold as "frozen yogurts".

What's the biological basis for this?


texts:
Out here in the mid german woods,  the kids found this skull:

Now we would like to figure out what it is. Started to look at various google image search results for all kinds of animals that came to our mind, but not only due to bad reception this takes long and lead to no result.
So what is a good structured way to start detrmining what this is?


texts: Anatomical differences between herbivores and omnivores

texts:
What are differences of herbivores vs omnivores? I do not mean dietary differences (obviously), but physical ones.

E.g., afaik herbivores have a much longer digestive tract than carnivores; then there is the difference in teeth, possession of carnivorous instincts or lack thereof, etc.

But where is the distinction between herbivores and omnivores? Is there a clear distinction at all, or is the border between the two groups somewhat fuzzy? Or are omnivores merely herbivores who are less picky?

EDIT

As pointed out in the comments, the last sentence seems to ask for dietary differences. It is not meant to; the only difference I am aware of is dietary, so it asks whether there are any anatomical distinctions, or the dietary is the only one. I.e. are they anatomically similar, and not distinguishable in the same way herbivores and carnivores are; hence are they herbivores that simply do not mind eating non-plant based food in a while?

I hope this serves to clarify.

EDIT 2

I realize that this question is quite broad, so while I am trying to get a good view of the bigger picture, partial answers will be more than welcome!


texts: Why does a tumour's genome change depending on the environment?

texts:
According to the book "Primer of The Molecular Biology of Cancer" by Vincent, Theodore and Ateven, the tumour cell is changed depending on its environment.

  performed genome-wide analysis on three tumor samples: a patient's primary breast tumor; her metastatic brain tumor, which formed despite therapy; and a xenograft tumor in a mouse, originating from the patient's breast tumor. They find that the primary tumor differs from the metastatic and xenograft tumors mainly in the prevalence of genomic mutations

Why the tumour cell changing on different places?

why suddenly the breast tumour cells changes on the xenograft tumour and why the metastasis on the brain are now different from the place they came from?

How does this alteration obtained? in the DNA or microRNA or something else?


texts:
In E. coli, there are only 47 different tRNAs but 61 potential anticodons. This is because, from what I understand, the third base of the anticodon can pair by wobble rules.

However, it is known that there is some correlation between tRNA pools and expression levels.

So if, for example, GUA and GUG were covered by the same tRNA, why are their codon usages different in a codon table? If one were only concerned with expression level, shouldn't they theoretically affect translation rates similarly?


texts: How long does it take to reset sense of smell?

texts:
I have noticed that when I go on vacation for several days and then come back home, there is a distinctive, relatively mild paint smell in my apartment complex. However, under normal circumstances, this smell is virtually unnoticeable to me.
What are the primary factors that cause us to become used to certain smells? And, is there any way to estimate how long it takes to 'reset' the sense of smell, so that these smells which we have become used to will again be obvious?


texts: Has the human capacity to heal from burns evolved due to actual burns throughout human history?

texts:
I just burned myself while cooking, and it occurs to me that although this has happened countless times, my skin always heals itself rather well after burns.
In this post I make various assumptions/guesses on topics I know very little about, so please forgive me of my uninformedness. I am just trying to explain the premise of my curiosity.
This got me curious, and it appears to me that it takes about 1 million years for lasting evolutionary change to take place.
Is the current ability of humans to heal after burns a result of humans being burnt throughout the hundres of millennia? Or perhaps the body just has a general healing response, and it kicks in for burns in the same way it does for any other injuries?
It occurred to me that there are rather few circumstances in nature that would produce temperatures hot enough to produce burns in humans. I realise volcanoes, hot springs and fires caused by lightning are notable cases, but it appears to me that these phenomena are rare enough that humans would seldom come into contact with them (especially because humans would probably avoid them).
This leads me to the assumption that the majority of humanity would only start getting burns relatively frequently after humans started controlling and using fire themselves. I have read up on the subject, and it does seem that humans have been using fire for at least hundreds of thousands of years, and possibly for up to one million years, according to some research.
However, would this have been widespread enough, and for a long enough time, for the current response (healing of burns) to evolve? Or is the healing process just generalised for all injuries?


texts:
From three answers to the same question at Quora I've learned of three forces that keep synapses together:

They are held together by cell adhesion molecules (e.g. neurexin and neuroligin).
They are surrounded by support cells (glia?) that hold them together.
They are packed densely together (and just couldn't move, even without specialized support cells).

I'm sure all of these ways of holding synapses together play a role.

  But are there others?

In any case it may make sense to ask

  which of these "forces" is the strongest, and how strong is it?

For example: If axonal tension is supposed to be a driving force of gyrification, the "weakest link in the chain" is probably the synapse. So the forces holding the synapse together must be strong enough to counteract the forces that drives the neurons in different areas of the cortex apart (whatever these may be). For "axonal tension" or "axonal tethering", see also here.


texts: How are sound waves amplified while traveling within the cochlea?

texts: How are sound waves amplified while traveling from the basal membrane to apical membrane within the cochlea? Are they amplified by the movement of the stapes?


texts:
The article Ants Swarm Like Brains Think really helped me to understand the way that neurons which are pretty dumb on their own (like ants) can work together to create a pretty genius system (a brain or an ant-hive). The idea is that both the neurons and the ants function majorly via positive and negative feedback, which is really neat to understand.

However as shown in that article, sometimes groups of ants get caught in something called a feedback loop. They can repeat the same action over and over because the positive feedback is just being relayed from ant to ant to ant in a circle, and the ants can do something unhealthy such as walk in a circle for days. I don't know any examples of negative feedback loops but they would presumably also be unhealthy.

As noted in the comments, this is an analogy, but not without a good reason: The brain does work via positive and negative feedback. And that does create the potential for feedback loops.

So I'm curious about what biological features in neurons help to avoid these feedback loops in our brains. How does the brain avoid feedback loops?


texts: Why would a bacterial population show initial growth when it is in unfavorable growth conditions?

texts: This figure shows the anaerobe E. faecalis grown in aerobic conditions, E. coli grown in restricted conditions that are not specified. Why do they show an increase in abundance initially? The black line is growth rate and to me I would think neither would grow at all.


texts: Flicker fusion threshold for insect eyes

texts: I searched on bio-numbers for flicker-fusion threshold of insect eyes in general and for flies in particular. Ruck, 1961 gives values for some flies. Is there any database maintained for these values? Is there any comparative study done for many flies/insects?


texts: Understanding beat annotations of arrhythmia ECG dataset

texts:
I'm trying to understand the rhythm changes in the MIT BIH dataset.

In annotations, there are 2 main types. Beat annotations and rhythm annotations.
Rhythm annotations (aux_notes field) contains rhythm changes. After each rhythm change point, there are empty strings till the next rhythm change.

Does that means all beats after the rhythm change are in the same rhythm till the next rhythm change?

For an example, take a look at the below wave with annotations (202 record of MIT BIH dataset from 21:19 to 21:49).

In the above diagram does the beats between '(N' and '(AFIB' are all normal rhythm beats? and does the beats after '(AFIB' are atrial fibrillation rhythm beats?

Here,

'(N' means a Normal rhythm annotation
'(AFIB' means an atrial fibrillation rhythm annotation

Postscript

You can reproduce the above diagram via this online tool. Parameters are,

Choose input window

Database = MIT-BIH arrhythmia database (mitdb)
Record = 202

View/edit window

Go to = 00:21:19
Window duration = 30 seconds


texts: Does DNA replication in 5' to 3' (leading strand) need RNA primase?

texts:
https://www.youtube.com/watch?v=27TxKoFU2Nw

In the above video it shows that during DNA replication, the lagging strand require RNA primase to add 3' -OH group for further addition of nucleotides. However, it hasn't been shown that the above strand ( leading strand) require it.

Besides, RNA is needed to initiate the polymerization because it has the 3'-OH.
But when I look at the structure of deoxynucleotide, it also has the 3'-OH but it does not have the 2'-OH. So why DNA cannot initiate the polymerization?

Thanks for your answer!


texts: Usage of the taxonomic classification "Pinnipedia"

texts:
According to ITIS the classification Pinnipedia is  invalid, and it is proposed to rather use Caniformia. The later group however includes a range of terrestrial animals as opposed to the pinnipeds (the seals), which only include marine mammals.

Is the term Pinnipedia nevertheless still accepted and used in scientific media? Is there any debate whether to use one and not the other?


texts:
It has around 3cm. Does it look like a European or Asian Hornet?
The place where I found it is Central Europe/Romania but, after the wikipedia picture for Asian Hornet's head .. it looks exactly the same.
Thank you!


texts: Identification of brown butterfly with orange/black/white spots

texts:
These brown butterflies are very frequent at my place now. Two or three can be found quietly sitting with their wings folded everyday, at different locations. It's a transition period between Autumn and Winter here, West Bengal, India.

What species is this?

Why is it taking shelter inside a house? They don't seem to move much, even during the day I've found one sitting quietly by the window. It wasn't flying off even after being disturbed.


texts: Which animal species are known not to murder (a targeted attack leading to death) members of their own species?

texts: Is there any evidence to suggest that some animal species do not murder  (a targeted attack leading to death) members of their own species? If so, which are the relevant species?


texts: Why does cutting onions cause tears? From a couple of sites, I found that it is because of sulfuric acid produced by onions. But I could not find more details. What is the biochemical pathway by which onions cause tears? Also, which compound is responsible for it? If it is enzyme-catalyzed reaction, can we just stop the production of this enzyme without causing any side-effects?


texts: Is the barcode COI sequence the sense or antisense strand of DNA?

texts: Is the COI sequence commonly used for DNA barcoding the sense or the antisense strand of DNA?


texts:
I'm reading now the Campbell biology book (10th), and on page 1063 is written:

  In all but the simplest animals, specialized populations of
  neurons handle each stage of information processing.

What does it mean "specialized populations of neurons"? I always knew that there is a population in biological hierarchy of creatures rather than the cells which assemble the creatures.


texts: Where do amino acids get attached to tRNA and where is it synthesized?

texts:
Some very basic parts of transcription/translation seem to be left out in various literature. I can't find the answer to this anywhere:

How exactly is tRNA synthesized? I realize that mRNA is synthesized through transcription and I know a lot about that. However tRNA is supposedly synthesized the same way but every time you read about transcription they just talk about how the mRNA then gets this and that...?

Where do the amino acids get attached? Is it in the nucleus or outside the nucleus?

Thanks.


texts:
Which elements of the following list are  assumptions of the Hamilton's rule?

Population structure (non-panmictic population)
Additivity

= Fitness of the heterozygote equals the mean of the fitnesses of both homozygotes

No epistasis or pleiotropy
Stable population size
Inifinite population size
Sexual reproduction
Selection on diploids or selection on haploids
Recombination (cross-over)
Mendelian segregation
Iteroparous population
smooth fitness landscape
mutation rate is high enough

Are there assumptions of Hamilton's rule that are not listed above?


texts: Why are humans and almost every species on earth symmetrical?

texts: I admit I'm not very learned on the subject of evolution, I just started researching it for myself about a week ago. One of the things that I don't understand is why humans and almost every other animal/bug/fish etc. on earth has a symmetrical body. What advantage does this have for the survival of the fittest? It must be quite important, since it re-occurs so frequently and early in the evolutionary family tree.


texts: Why is double stranded DNA considered to be one molecule?

texts: Wikipedia, for example, refers to DNA as "a" molecule, not two separate molecules forming a double-helix structure. Isn't this technically incorrect? There are two separate polynucleotide strands (each that can be considered one molecule on its own as the monomers are joined together by covalent bonds), and the strands joined together by hydrogen bonds and not covalent/ionic bonds along their length. Doesn't that exempt them from being considered one molecule, as the bonds joining them are intermolecular and not covalent or ionic?


texts: What is the identity of this spider from India?

texts: I came across this strange guy today at my classroom in Tamil Nadu, India. It is a spider which is not very much bigger than an ant but with an artistic body. He has 8 legs, but the two on the front are raised above his head, just like a crab does. Can anyone identify this little guy?


texts: Why is alcohol purged from the body more slowly when we sleep?

texts:
It is a popular belief that when you get asleep after drinking alcohol, in the morning you have higher level in your blood than if you stayed awake the whole night.

Is this true?
If so, why? Is it because the liver works more slowly while sleeping, or because the intestines work more slowly and there is still more alcohol in the morning to be processed by the liver?


texts:
When you place a cell into a hypotonic solution, water rushes into it and it bursts/lyses. Thus, the cell dies.

However, when you place a cell into a hypertonic solution, water rushes out of it and it shrivels. The membrane is still in tact and all the organelles are still held inside. Why is having a shriveled cell a problem then?


texts: What are the various types of plugs found in a bee house and how do they help us with identification?

texts:
I have a Mason bee house with small tubes that is currently buzzing with life but I am completely clueless about what's in there. Some plugs seem made of clay, some of crushed leaves, some of resin, some look like just a little film...

I figure it's possible to learn about what is living in there (approximately) going by the type of plug, and maybe the size of the tube, but I don't know where to start. I'm in Eastern Canada if this makes a difference.


texts: In the notch signaling pathway, what is Fringe activating?

texts:
Take a look at the notch signaling pathway in human from KEGG : https://www.genome.jp/kegg-bin/show_pathway?hsa04330

I want to know what is Fringe activating. It is not pointing to another gene or protein, it is pointing to an interaction. What does that mean?


texts: With so many different species of fish with often very minor differences, how is the precise species identified authoritatively?

texts:
While it seems to me that common mammal species are usually distinct enough that there isn't much trouble in accurately defining and identifying a specific species, for example of a deer, I see that with fishes there are often a whole lot of very similar species with close to none differences between them.
How can an individual specimen be authoritatively assigned to a specific species, is there an authoritative catalogue of features that one can look up to be able to say with certainty is an examined specimen of a certain species or not?
For example in the family Scaridae there are species Chlorurus bleekeri, Chlorurus bowersi, Chlorurus gibbus, Chlorurus frontalis, Chlorurus gibbus, Chlorurus japanensis, Chlorurus perspicillatus, Chlorurus strongylocephalus, Chlorurus troschelii which are all kinds of parrotfish very minor differences if I look at photos on FishBase.
How did anyone even decide these are distinct species of fish, instead of varieties of the same species, and then is there a central authority where newly defined species like this are described in enough detail for future occurrences to match with the same species name?