texts: I am conducting an experiment on how different pH levels effect the growth of E.coli. After researching, it is predicted that the most acidic pH level (pH 2) will be most effective at killing (or at least slowing down the growth) of bacteria. But my question is what does pH actually do to the bacteria cell and the biology behind it. How does the pH actually affect the E. coli cell itself? Thanks for your time.


texts: I was reading this paper: https://link.springer.com/article/10.1023/A:1011398431524, which makes claims based on the the idea that frost can increase soil fertility. How/Why will frost increase the fertility of the soil? I was always under the assumption that frost was bad for soil and plants in general.


texts: How could cyanobacteria survive the anaerobic conditions of ancient earth?

texts: I was reading about cyanobacteria and came to know that they are the first organisms that filled the atmosphere with oxygen around 2.3 billion years ago but then I realized that they themselves are aerobic and I couldn't understand how an aerobic organism would be able to survive the oxygen poor atmosphere in the first place to make enough oxygen that filled the whole atmosphere and caused almost all anaerobic organisms go extinct


texts:
I found this statement from my biology text book,

  "The sieve tube elements and the companion cells are connected by pit fields present between the common longitudinal walls".

Is the pit field same as Plasmodesmata ?


texts: Which hormones/factors affect Calcium absorption in the small intestine and its regulation?

texts:
I think the question is very broad and cannot find precise mechanisms.
I am not sure about the precise mechanisms of the regulation.

I think they are at least Vitamin D, diffusion and specific calcium channels: calbindins.
More specifically, calbindin-D9K and the basolateral calcium pump transport calcium from cell interior to extracellular space.

The calcium gradient should also be free, -2-6 mmol/l, in the lumen to allow diffusional calcium absorption from the interstitial space.
Similarly, free calcium concentration in the extracellular fluid of the lamina propria.

I think that the most important mechanism for this absorption is the electrochemical gradient of sodium across the epithelial cell boundary of the lumen, similarly as for carbohydrates.
To keep the extracellular space free from calcium, the NA/K-ATPase i.e. sodium pump has to work.

I did not find any hormones that affect the intestinal calcium absorption.
Which factors affect calcium absorption and its regulation?


texts: In a benign tumor, p53 gene does not work. I know that our cells constantly are mutating and the p53 fixes this. Hence, why does it take so long(or in some cases never) for a benign tumor to become a malignant one? I would imagine a malignant cell would rise rather quickly.


texts: How different are tissue-specific fibroblasts from each other?

texts:
I am planning to utilize a new system in our lab, in which I will co-culture cancer cells from different tissues with fibroblasts.
I have the option to receive skin-derived primary fibroblasts. I have been told the normal fibroblasts are very similar all over the body. Is this really true? I assume that fibroblasts secrete factors, for example, that are tissue specific. The question is, how quickly do they adapt to a new environment? For example if I take these skin-derived fibroblasts and co-culture them with breast cancer cells, how long will it take the fibroblasts, if any, to become more like fibroblasts derived from the breast?


texts: Why did humans get rid of their tail in the evolution?

texts:
Most mammals seem to have tails. Even human embryos start out with a tail. But here we are with nothing but a tail bone that hurts when we trip over backwards. What is it good for? Why don't humans have a tail to wag around?

Some science fiction (like Avatar) even portrays a tail as something sexy. And we all have experienced that a third arm of some kind would be very useful once in a while. Especially since humans stand up alot of the time it could help us keep the balance.

Is there any utilitarian evolutionary explanation for why we don't have tails any more? Is it only because we try to be different?


texts: Why does glomerulus don't allow white blood cells to leave?

texts: The glomerulus in nephrons are just a ball of capillaries, so why can't it allow the white blood cells to squeeze though the epithelial cells into Bowman's capsule just like the formation of tissue fluid in other capillaries by filtration?


texts: How was the Huntington's disease gene's location found?

texts:
I read in the book "Why we get sick." by Nesse and Williams that:

  Steady detective work and fabulous luck have enabled geneticists to
  pinpoint the Huntington's gene on the short arm of chromosome 4.

I want to know what was the "detective" work and the fabulous luck - the whole story of the discovery of the location of the gene.


texts: Is receptor antagonism just long-term binding?

texts:
By my understanding, a substance that binds to a receptor and activates it is called an agonist, while a substance that binds to a receptor without activating it is called an antagonist. (Wiki) What is the fundamental difference between binding to a receptor and activating it?

EDIT: I guess the receptor is a complex enough beast that fitting into it and staying there can be accomplished by some sections of the interface being completed, without necessarily completing the "usual" interfacing process between the receptor and its agonist -- thereby blocking the receptor geometrically without imparting the proper energy to it chemically.


texts: Model for calculating muscular activity from external measures

texts:
A physiologist wants to measure the intensity of the activity of a muscle or muscle group over a certain period of time. But the physiologist cannot measure what happens inside the the muscle itself (the strain on fibres, the blood flow and nutrient #Umsatz#, etc.), so the physiologist measures what the muscles do – the duration, force and frequency of contractions – and unifies these measures into a concept of "intensity of muscular activity" or "strain".

For example, think of an office worker clicking his or her mouse button. The physiologist conceptualizes the intensitiy of muscular activity as consisting of three partial aspects: the force with which the mouse button is pressed, the duration for which the mouse button is pressed, and the frequency of pressing the mouse button.

It is important to consider both frequency and duration, because there might be a difference between pressing a button for 30 seconds and then resting for 30 seconds, and pressing a button for one second, resting for one second, and then repeating the procedure for a minute. The same overall duration of muscular activity spread differently over the same period of time might "strain" the muscle differently.

So the physiologist measures these three aspects, and then calculates the latent construct "muscular activity" or "strain" from the three measures. But what formula would the physiologist use?

I'm pretty sure someone in sports, occupational or military medicine must have modelled this construct theoretically and/or validated it experimentally, but I cannot find anything in the literature.

Does anyone here know any models for calculating amount of muscular activity over time from external measures?


texts: What is the significance of Nissl bodies? How are Nissl bodies different from any other RER seen in any other cell of the body?


texts: What are the atmospheric requirements for large dinosaurs? and are the atmospheric constituents for supporting large dinosaurs any different from the atmosphere today?


texts: Is there an optimal illumination level for human habitats/workplaces?

texts:
I know of melanopsin, a photo pigment in mammal eye that helps regulate circadian rhythms. It responds most strongly to blue spectrum light. There have been experiments that demonstrated that intensity of light is proportional to the impact on circadian rhythm regulation/ melatonin suppression.

This is why I'm interested if there is some optimal illumination intensity that has been demonstrated to result in better health/cognition in humans. I heard anecdotal reports of full spectrum lighting improving attention in classrooms, but is there some chart or figure which says how much is "too much light".


texts: How many recombinations occur in an average human chromosome?

texts: And is it a different number depending on which chromosome we choose (disregarding the change of this probability due to the differential size of the chromosomes)?


texts: Quantifying the number of fragments from RAD library

texts:
I have a series of single-end reads from a RAD library of 48 uniquely tagged individuals in fastaq format. The data comes from a small MiSeq run. I want to know the number of unique fragments per individual/barcode, but I'm not sure how to go about getting that number. I'm new to bioinformatics, but I was able to use Stacks to demultiplex the library using the process_radtags function.

Could someone help? Thanks!


texts: Please help me identify this plant. This was shot in the assam-meghalaya region of india.


texts: Some guide books on biology continue to state that Prokaryotes respire through mesosomes. However, they don't exist in living cells. What is the stand now?


texts:
I've seen these jellyfish in thailand and was wondering what species they were. All I know is that there are lot in the Chonburi area and they sting in not deadly but hurts.

Images for the jellyfish

Thanks for the help!


texts: Name of this kind of stain on fruits and how do they form

texts:
Last year I made some photos with avocados touched by some stains. They were even more delicious than the regular ones.

What's the name of such stains and how do they form? My guess is that they form because the fruit was hurt but maybe that's just me.

Later edit: A farmer told me it's a disease. Then I've found that it looks quite similar with apple scabs. Is it correct to call this "Avocado scab"? Is it made by the "Sphaceloma perseae" fungus?

Here are the photos:


texts: What are the mechanistics of stinging nettles?

texts:
There is a lot of research on why nettle extracts causes skin irritation and a stinging sensation. However, I cannot find information on how the extract is injected in human skin. Similarly, I haven't been able to find information on  how the pressure is built up in the trichome, nor how the silica tip is inserted in the skin.

Suggestions for articles or books on this topic are welcomed.


texts: Does zygosity have meaning for mitochondrial variants?

texts:
I am working on a system that annotates variants in human DNA sequences. One of the pieces of information reported is the zygosity of the variant. I noticed that mitochondrial variants are also shown to be either homo- or heterozygous.

How does that make sense? Does it make sense? As far as I know, the mitochondrial DNA is just a single, circular DNA molecule. So I can understand considering all mitochondrial variants heterozygous, by definition. I could also accept that one could think of them as homozygous by definition. I just don't see how some variants can be homo- and others heterozygous. Am I missing something or is the annotation system I'm using not making sense?


texts: Why do genes, encoding the same proteins and in the same conditions, have different expression?

texts:
Is it possible that two genes, which come from two different cell cultures and which encodes the same protein, produces different quantity of mRNA? If yes, why?
My question comes from the fact that I am doing statistical analysis of a microarray dataset for the hyperthermophilic archaeon Pyrococcus furiosus exposed to gamma irradiation. Microarray experiments measure relative quantities of mRNA in a cell. My file has values, for each gene of the genome, that are positive or negative since the scientists who performed the experiment made the log10 ratio between the fluorescence intensity of the sample that was irradiated and the reference sample (not irradiated). Indeed, in the microarray experiment we have two channels that typically are one for the "controls" and the other for the cells which are stimulated by an event (in this case the event is gamma irradiation), in order to make a comparison.
In my dataset there are two columns (that are indicated as "reference") that refer to the case in which they should have put the cell cultures not irradiated in both the two channels. I would expect that the values in the file corresponding to these two columns are 0 (since they are the log10 ratio between the intensities of the signals of the genes which encode the same protein and that are in the same conditions). Instead they are different from 0. Therefore I wonder what is the reason for which there is different quantity of mRNA produced from two equal genes?
I made a graph of relative mRNA produced (calculated as I explained before) vs time, in which you can notice that the relative mRNA produced of the reference  (I called them as "Ref" on the horizonal axis) is not 0.

Is it only due to some noise or are there biological reasons ? (the picture refers to a gene which encodes Ferritin-like proteins but it is the same story also for other genes).
Even though I think that my interpretation of the data is correct, I tell you that the dataset I am talking about is here, if you want to have a look.


texts: Why does the direction of endolymph flow oppose direction of body motion?

texts: In the semicircular canals, the endolymph always flows in a direction that is opposite to the motion of the vestibular apparatus itself. I’m having trouble grasping why this is, and I would greatly appreciate it if anyone could give me some physics insight into this.


texts: How do centrioles auto-locate to opposite sides of cell during mitosis?

texts:
I realize that centrioles are made of 9 triplets of microtubulin wound together with a hollow core, and that they are responsible for the configuration of the spindle during mitosis. The spindle fibers attach to the kinetochores of the sister chromatids and pull, ultimately separating them in preparation for cytokinesis.

How do the centrioles recognize where to go in the cell, such that they are oppositely positioned with one another? Is the mechanism similar to how neurons "find their way" during development to forge the correct connections that give us sight, etc, but on a subcellular scale?


texts: What if our whole body is made up of cancer cells?

texts: Today I learnt in my biology class that cancer cells are immortal.  That left me wondering what if our whole body is made up of cancer cells?  Will that make us immortal? Is it possible or why is it not possible?


texts: How do anticholinesterase pesticides kill nematodes?

texts:
Compounds that inhibit the enzyme acetylcholinesterase are commonly used as pesticides. In animals with centralized respiratory systems controlled by the nervous system, poisoning with an anticholinesterase would lead to death due to respiratory arrest. I presume that, in insects, the inhibition of AChE would lead to closing of the spiracles necessary for respiration
However, nematodes and other worms rely on diffusion of gasses for respiration and do not have respiratory systems controlled by a nervous system, so how would inhibition of AChE by agents such as aldicarb kill them, especially if the pesticide in question happens to be a reversible inhibitor?


texts:
I knew from this website (https://www.etymonline.com/word/plasmid) that the word "plasmid" is a combination of "plasma" + "id" , where "id" means: belonging to or connected to.

But I don't understand how plasmids are connected to plasma even though they exist inside the bacteria cell cytoplasm not inside the blood/plasma


texts: Are there any place in human body that safe to implant things and have large amount of blood run through?

texts:
Suppose there was a fuel cell in the size of AAA battery that could convert human blood sugar into electricity. Assume it safe and efficient without causing allergic reaction. But to avoid the risk of it disintegrate and malfunction it should be put in a place that far away to any critical organ as much as possible. It also need to have large amount of blood to supply anytime

Which place in human body would be the best to put that device in?


texts: Did Mendel believe that proteins are hereditary substances?

texts:
Scientists first thought that proteins, which are found in chromosomes along with DNA, would turn out to be the sought-after genetic material. Proteins were known to have diverse amino acid sequences, while DNA was thought to be a boring, repetitive polymer, due in part to an incorrect (but popular) model of its structure and composition.
Was Mendel (1822-1884) one of these scientists?
Note that in 1869, Friedrich Miescher isolated "nuclein," DNA with associated proteins, from cell nuclei. He was the first to identify DNA as a distinct molecule.


texts:
Penis don't have bone like ears & nose, then why why male penis not considered as cartilage?

en.wikipedia.org/wiki/Cartilage


texts: Effect of pH on life? Use buffer or HCl? How about lactic acid?

texts:
I'm trying to find the effect of pH on living things like E. coli and such. At first I thought of using a buffer solution which maintains its level of pH, but it's possible that the inactive ions of each buffer have their own effect on living things that I can't account for. On the other hand, I could use hydrochloric acid and sodium hydroxide at different concentrations by diluting it. This will be a little bit more effort (I'll be diluting the acid and base myself), but much cheaper than the buffers, and I'll know that the only other ions present beside H+ and OH- are just Na+ and Cl-, the ingredients of table salt. According to this paper, the effect of pH on the population also depended on the acid (HCl vs lactic acid).

I would like a second opinion on this:
If I'm investigating the effect of pH on growth of living things, do I use specially made buffers or just properly diluted HCl and NaOH?


texts: Mild introduction to selective advantage of intelligence/nervous systems in animals?

texts:
I have a general understanding of why intelligence, i.e. nervous systems in animals, is advantageous: processing information allows an animal to adapt to its environment dynamically and perform complex sequences of actions that an animal without a nervous system could not. Larger nervous systems potentially allow for more possibilities herein.

However, I am interested in a deeper understanding of the factors that cause a species to at first develop, and increase the size of, a nervous system, and different forms of cognition:

what type of environment favors the development of a nervous system in a species?
what type of environment favors life-long learning and adaptivity (neiroplasticity?) of a species (as opposed to a fixed neural structure after development in an organism)?
what type of environment favors the development of goal-oriented planning (as opposed to simple impulse-response patterns)
what type of environment favors development of "cognitive ability" in species?

Do you know of a good book that addresses questions like this?


texts: Name/Examples of Traits whose benefit is non-obvious and/or which evolve despite apparent mal-adaptivness?

texts:
I'm a graduate student in cognitive science doing work on people's explanations and learning, particularly having to do with natural selection.

Often, students misunderstand natural selection as a "goal-directed" process, one in which organisms are directed to adapt towards beneficial traits. This kind of thinking can be tempting, since most evolved traits are beneficial in obvious and straightforward ways.

However, I'm very curious about traits whose benefits are NOT at all obvious, and can only be understood under careful consideration of the evolutionary process.

An prototypical example would be the evolution of altruism, or of homosexuality. But I'm looking for more examples like these, and preferably ones that are more specific/concrete (e.g., the existence of a specific trait/behavior, rather than someone general like altruism).

Any help would be appreciated.


texts: What does chrUn mean in the output from a Bowtie run on human sequences?

texts:
After having performed an alignment using bowtie2 and GRCh38 as a reference sequence, I got inusual matches on chrUn.
Here a small part of the SAM file:

@SQ     SN:chr22   LN:50818468
@SQ     SN:chrX    LN:156040895
@SQ     SN:chrY    LN:57227415
@SQ     SN:chrM    LN:16569
@SQ     SN:chrUn_KI270424v1     LN:2140

All the other chr values are clear to me (M indicates the Mitochondrial DNA, while 22, Y and X are just the usual chromosomes number/name) but I couldn't figure out what chrUn stands for and what about that code after the _?


texts: Self-fertile PRUNUS: Approximately how much of the genome gets rearranged by meiosis?

texts:
I'll admit that I don't have a background in science, so this might be a stupid question. Suggestions and edits are welcome. The question is related to a similar question I had here: What DNA does a self-fertile plant's seedling have?

Some prunus plants are said to be partially self-fertile. An example is prunus tomentosa. I've been informed that through self-fertilization (a.k.a. selfing), meiosis occurs, which rearranges the genome.

  ...when selfing, meiosis is occurring (and therefore segregation and
  recombination) so that the offspring is not an exact clone of the
  parent but rather some kind of a rearrangement of the parent genome
  (with a few mutations of course). Source

Approximately how much of the genome of a self-fertilized seed is impacted by meiosis? Is a large amount of the genome rearranged, such as 25%? Or less than 1%?


texts: What is the difference between naive and adjusted p-values in a GWAS study?

texts:
What is the difference between a naive p-value and an adjusted p-value in the results of a GWAS study? See from this paper:

  After Bonferroni adjustment, a single gene, DCTN4 (encoding dynactin 4) on chromosome 5q33.1, was significantly associated with time to chronic P. aeruginosa infection (naïve P = 2.2 × 10−6; adjusted P = 0.025; Supplementary Fig. 1).


texts:
The thecal sac, or dural sac, is the membranous sheath of dura mater that surrounds the spinal cord and the cauda equina. The thecal sac contains the cerebrospinal fluid in which the spinal cord 'floats'.

Is the dura matter ectoderm? I know neural crest and such is ectoderm. But the meninges, in particular the dura, where do they come from?


texts: Why are nucleic acids negatively charged at physiological pH?

texts: Why do nucleic acids and mononucleotides have a negative charge physiological ph?


texts: Is it possible to have a random un-mutation of genes?

texts:
According to this article:

Gene mutations can be classified in two major ways:

Hereditary mutations are inherited from a parent and are present throughout a person’s life in virtually every cell in the body. ...

Acquired (or somatic) mutations occur at some time during a person’s life and are present only in certain cells, not in every cell in the body. These changes can be caused by environmental factors such as ultraviolet radiation from the sun, or can occur if a mistake is made as DNA copies itself during cell division. Acquired mutations in somatic cells (cells other than sperm and egg cells) cannot be passed on to the next generation.

The "random mutations in genes" appear to be called Somatic mutations. For the context of this question, these are the mutations I am asking about (not the hereditary mutations).
My question: Is it possible for there to be a random un-mutation of genes? Some sort of reverse-somatic mutation. If so, have there been any clinically proven instances of it?
After-thought: Or is it all a Somatic mutation, aka you can experience a mutation that makes you more susceptible to a particular disease, then another mutation that makes you less susceptible to the same disease... so not necessarily a reverse mutation, but a 'forward' mutation that negates the original ill effect of the first mutation.


texts: Could blood transfusions from COVID19 surviver be worth researching as a possible form of treatment

texts:
As a general viral immunology question (rather than seeking personal medical advice).

Would a blood transfusion from a COVID19 surviver to a sufferer be worth researching as a possible form of treatment? There is evidence in other animals (elephants) that blood transfusions are beneficial against viruses.
BBC Chester zoo

More specifically would lymphocytes and other cells able to attack the virus from the donor outweigh the resulting increase in virus burden caused by adding the donors blood into the sufferer? and how does the is change over time from the time of the survivers recovery?

Needless to say this procedure risks crossing strains of COVID19 and other risks so would need thorough analysis of such risks before being practiced.


texts: What is the mechanism by which aminoglycoside antibiotics (such as streptomycin and gentamicin) damage the mechano-sensory hair cells of the auditory and vestibular system? (Could this be seen as evidence for Lynn Margulis' theory that these cilia are descended from bacteria?)


texts:
Coming from a software engineering standpoint, suppose I have a string of code like so:

... 5'-ATAGAC-3' ...

... 3'-TATCTG-5' ...

Assume the above code is part of a larger segment. Now, reading from 3' to 5', the promoter and operator would be somewhere before the structural gene on the 2nd stand:

(Promoter) (Operator) ... 3'-TATCTG-5' ...

Where would it be on the first strand? From what it looks like, the first strand codes for a completely different protein than the second stand:

... 5'-ATAGAC-3' ... (Operator) (Promoter)

Yet, the two strands are complementary.


texts: What is the typical concentration of Calcineurin (PP2B) in CA1 dendritic spines?

texts: I am trying to find the concentration of CaN (PP2B) in dendritic spines, there is a computational model (doi:10.1073/pnas.0804672105) that uses the quantity of 1uM in the dendritic spine. I think this value is not correct since it was measured long time ago (Goto Brain Res. 1986 Nov 5;397(1):161-72) and was given as Hippocampus 1.45 -+ 0.39 (ug/mg of protein).


texts: What does "substoichiometric amounts" mean in the context of molecular biology?

texts:
Recent paper:

  PRC2 is composed of the histone methyltransferase EZH2, EED, SUZ12,
  and the histone binding proteins RBBP4 and RBBP7. JARID2, AEBP2, PHF1,
  MTF2, and PHF19 are also present in PRC2 in substoichiometric amounts.

Does this have a more specific meaning than "very little" or "very small amounts", which I presume is what it means?

Paper (paywalled): http://genome.cshlp.org/content/26/7/896.abstract


texts:
I have attached a photo. I know the Nepali name for this fruit but not its common name in English and its scientific names. In Nepal we call it as 'lahare Aanp' (meaning Climber Mango). This fruit is a climber type like cucumber.

Does anybody know its common name in English and its scientific name?


texts:
I am studying mathematical models of transcription and translation and I am wondering:

In a particular genome, how many copies of a gene coding for one particular protein should one expect? Are they all transcribed at the same rate?

I know humans have two copies of each chromosome, so the answer would be at least 2 in humans. But I wonder if one particular gene coding for a protein we need in abundance might be present in many copies in the genome to increase expression.


texts: Cyanobacterial photosynthetic oxygen yield

texts:
I am somehow not convinced that biotic factors are solely responsible for creating 21% of atmosphere (around 40 million moles of oxygen).
There may be additional issues here. Since cyanobacteria produced oxygen, it should have developed antioxidant machineries. By the time cyanobacteria flourished, some dependent heterotrophs must have evolved and they also would need antioxidants, as they are expected to thrive in close proximity to the autotrophs. There is a likelihood that aerobic respiration co-evolved with biotic oxygenesis. This would have further delayed the build up of oxygen in the atmosphere.

Does anyone have an idea of what is the photosynthetic oxygen production rate per gram biomass of cyanobacteria? Since photosynthesis must have happened mostly at the surface of the water (limnetic zone), the total biomass would be restricted. Then it might be possible to calculate the time required to achieve the oxygen levels of 21%.

This measure can indicate whether the current theory is plausible or not.


texts: This is very small. About the size of a grain of rice. I Felt it crawling in my hair.  When I brushed my hair off this fell out in the sink. I was wondering if it's lice. I'm in Mojave county Az


texts: What voltage damages a neuron or a group of neurons?

texts: Neurons are stimulated for research and therapy purposes. How much voltage (current, duration, etc) can a neuron or a group of neurons, in humans, take without being damaged?


texts: Why are red blood cells not attacked by NK cells?

texts:
All cells containing a nucleus present MHC-I, while some specialized cells present MHC-II in addition to that. Since erythrocytes lack any MHC why do natural killer cells not attack them?

It is my understanding that any cell which starts presenting foreign peptides on MHC-I will undergo apoptosis after Th finds them, or if they stop presenting anything at all, they will be eliminated by the NKs.

So what mechanism prevents erythrocytes from being destroyed by the immune system?


texts: How does being afraid or nervous affect mental performance?

texts: It's known that when somebody is not relaxed (nervous,worried....) , they can't concentrate , what exactly in being nervous is the problem?


texts:
What are the physiological events that occur after there is endothelial interruption in the blood vessel?

What does endothelial interruption mean here? And what could be the physiological events?


texts:
Are there any well-founded studies that authoritatively demonstrate negative effects from the use of nail polish, particularly in children?

I've been brought into the fray of a couple of folks who are having a rather serious debate of whether or not a child of 6 or 7 years of age should be allowed or discouraged from wearing traditional (not the "safe brands") nail polish.  It was my opinion that it is better err on the side of caution and that one should rather be safe than sorry, opting for safer non-toxic alternatives if fingernail paint must be worn by such a young child.

The debate has boiled over into allegations of quack science and over-caution.  Seems absurd to me, but I wanted to do some more research into the biology of the matter.

A recent report appears to urge on the side of caution, but could someone help to point me in the right direction with regards to substantiating valid scientific claims and studies that fingernail polish can, has and/or does contain harmful material that should not warrant careless usage, especially by younger children who may be more hormonally susceptible to adverse effects?

I'm really looking to button up the "quack" or kooky science arguments if possible and to put this debate to proverbial rest.


texts: Understanding Hodgkin-Huxley's model and activation variables

texts:
This question is about the Hodgkin-Huxley model as introduced in Eugene M. Izhikevich, Dynamical Systems in Neuroscience, p.33 ff.

I'm having trouble to understand and interpret the differential equation for the activation variable $m$:

$$\dot{m} = (m_\infty(V) - m)/\tau(V)$$

which enters via

$$p = m^a h^b$$

into the equation

$$I = \bar{g} p (V − E)$$

for the net current $I$ generated by a large population of identical
channels where $p$ is the average proportion of channels in the open state, $\bar{g}$ is the maximal
conductance of the population, and $E$ is the reverse potential of the current.

$m$ is the probability of one of $a$ activation gates to be open. Interchangeably: $m^a$ is the proportion of open activation channels (assuming all of its activation gates must be open simultaneously).

The differential equation might give us $m$ as an explicit function of time but it – explicitly – involves $V$ which is – implicitly – another function of time, which in turn depends on the number of open gates. Things are horribly complicated!

On the other hand — since it's about voltage-gated channels and there are "immediate" voltage-sensitive regions in the channel protein which presumably don't have memory ("the single channel has no memory about the duration of its own state"), but possibly a time lag — I expected the being-open-probability of an activation gate to be a "pure" (possibly time-lagged) function of $V$.

My question comes in two disguises

(1) Given two explicit functions $m_\infty(V)$ and $\tau(V)$ like these:

together with $m(0)$ and $V(0)$, how could we ever arrive at an explicit solution for $m(t)$, assuming that $V(t)$ depends somehow on $m(t')$ for $t'\leq t$, but possibly also on some injected currents.

(2) How can an intuitive and sensible interpretation of the terms in

$$\dot{m} = (m_\infty(V) - m)/\tau(V)$$

be given? What does the time constant $\tau(V)$ and its dependence on $V$ mean? In which respect and by which hypothesised mechanism is the gate "faster", when $\tau$ is smaller? How can the voltage-sensitive steady-state activation function $m_\infty(V)$ be intuitively explained other than by "giving the asymptotic value of $m$ when the potential $V$ is fixed (voltage-clamp)" or by some complicated description of experiments to determine it? What does $m_\infty(V) - m$ mean, i.e. "the deviation of the current activation from the steady-state activation"?


texts: Why do these earthworms stay between the road lines?

texts:
This article shows pictures of earthworms during floods in Texas. The worms ball up, supposedly in order to survive the floods.

Photo Credit: Texas Parks And Wildlife Department

Can anyone explain the phenomenon a little? I can't seem to find anything about this online. I know that earthworms surface when it rains for oxygen, but it seems weird that they meet in the middle of the street.


texts: In percentage, how much is the human genome (DNA) similar to the mouse genome?

texts:
Some guy argued with me against evolution theory, and he claimed that human and mice share 98% just like human and chimpanzee.
I've tried to search online for a simple and accurate answer, but I couldn't yet.
In simple words, how much is the human genome (DNA) similar to the mouse genome?

Please use numbers as much as you can and provide references.


texts: Why do living organisms replicate itself or procreate

texts:
Why do living organisms spontaneously replicate itself or "procreate" (my understanding is that it does).

From a uni-cellular and micro-organism point of view. Is there some sort of stimulant in the environment? A chemical reaction that causes it? Is is there a physical or emotional motivation? Is it by choice?

Note: I may have some terms used wrongly as I am not a biologist. In this question, I am interested at living organism nearer the forms of single smallest unit of life form.


texts: If red blood cells have no mitochondria how are they able to metabolize glucose?

texts:
I have read that red blood cells (RBCs) metabolize glucose. However they don't have any mitochondria because there is just so much hemoglobin that there is no room for mitochondria without expanding the cell.

So how is it possible for them to metabolize glucose if it is mainly O2, CO2, H2O, fatty acids (in cell membrane), and hemoglobin?


texts: Doesn't meiosis form two pairs of similar cells and two pairs of opposite cells?

texts:
I am learning about meiosis in biology. I've learnt that the crossing-over in metaphase I only exchanges small portions of DNA at the tips of the chromosomes. Doesn't this mean that:

After meiosis I, there will be two cells that will be almost opposites (for each chromosome, if one cell has the mother's chromosome, then the other will have the father's chromosome), except for the parts where crossing-over happened
After meiosis II, each cell produced in meiosis I will produce two similar cells (the only differences will be where crossing over happened in one but not both of the chromatids)

This means that there would be a rare chance of two of the sperm cells produced by a single meiosis fertilizing two eggs, in which case we could have:

Almost-identical twins
Very different twins, which would have less than the normal 50% of DNA in common

Am I right about this?


texts: What is this black shelled insect found in Western Arkansas?

texts:
This bug was running around my driveway last night. It was very fast and wouldn't hold still - this is about the clearest shot that I got of it. As far as I could tell, there were no legs behind that 3rd segment - it was just dragging those.

I've never seen this, or anything like this in Arkansas. What is it?


texts:
From a short introduction to immunohistochemistry controls:

Isotype Control
This control can be utilized when working with monoclonal primary antibodies. The sample is incubated with antibody diluent, supplemented with a non-immune immunoglobulin of the same isotype (for example, IgG1, IgG2A, IgG2B, IgM) and concentration as the primary monoclonal antibody. The sample is then incubated with the secondary antibody and detection reagents. These steps will help ensure that what appears to be specific staining was not caused by non-specific interactions of immunoglobulin molecules with the sample. Background staining should be negligible and not resemble specific staining.

I googled and found out that some pathological agents can bind immunoglobulins in a non-immune fashion, i.e. by binding to their Fc regions. But that still leaves me in the dark on "non-immune IGs".
Maybe it is an IG with which the secondary antibody will not bind?
Or maybe it's an IG that has no activity against the target antigen?


texts:
We have hair all over the body except palms.
What is the biological reason behind this?


texts: How long does it take to pass out from oxygen deprivation? The person is panicked and screaming so they accidentally breathe water into the lungs. So how long would it take for them to pass out? After they pass out they are administered Mouth-to-mouth resuscitation immediately and are only out of it for a couple of half a minute. Then they are taken to the hospital. Would there be any long term affects to the body?


texts: When to measure resting heart rate and blood pressure for following day-to-day trend?

texts:
I'd like monitor my resting heart rate and blood pressure to see how they are affected by regular cardiovascular training and other events in life.

When should I take the measurements in order to reduce day-to-day variations? In the morning or evening? Before or after eating? Right after waking up?

Of course I'll make sure to follow good routines when measuring, but the ones I've found prescribed by hospitals don't state an appropriate time of the day.


texts: Do the majority of fish lack scales on their heads?

texts:
Based on pictures, it seems to me that a vast majority of fish species that have scales do NOT have scales on their heads.

Is that fact true?

To make this properly answerable:

lets' define a "majority" as >70% of fish species. But frankly, I'm more interested in actual numerical answer than whether it passes some arbitrary threshold or not.
The universe which I'm interested in measuring the percentage are fish species that have "normal" (Cycloid and ctenoid is the technical term, I believe?) scales on their bodies.

If that's not specific enough, you can restrict the universe to species in Actinopterygii (ray-finned) that have scales.


texts: Question about the quantity of orchid species and genera

texts: One flower which I am reminded of is the orchid and conjointly, the Orchidaceae family. I am surprised when discovering there is an abundance of species and genera, hence I would like to know the exact number. Moreover, what is the reason, is this a quality resulting from angiosperms?


texts: Why more than one chromosome in an organism?

texts:
Why not one chromosome to house genome in organisms but multiple?
Is it for epigenomic purposes?


texts:
I have visited various authenticated websites and other materials and learnt that a complete sperm development takes approximately 64 days.

My doubts :

If sperm truly takes 64 days to develop, how can a man ejaculate multiple times (e.g., 4-5) in a day and still have sperm come out each time? Why don't all the sperm come out at once? And each time he ejaculates, the sperm are complete (i.e., the "head" and "tail" portions are always included), right?
Does frequent ejaculation, then, reduce the sperm count of each subsequent ejaculation? If so, do the sperms remain depleted for extended periods (i.e., 64 days), or are they replaced more regularly? At what rate are they replaced?


texts: Can a cell start a mitosis if it lacks energy or molecules to complete it?

texts:
I'm wondering whether a cell can start a mitosis if it lack molecules or energy to fully complete it. From what I'm reading on wikipedia the cell passes most of its time in the interphase in which the DNA is replicated and then there's the G2 checkpoint to make sure mitosis can start.

However I'm not sure all of this is enough to ensure that the cell has sufficient energy to fully complete the mitosis (is the cell "fueled" in energy and molecules during the mitosis or does it has everything needed before starting it?).

Edit: I'm considering this question for humans in particular, or animals in general if the answer is the same.

When I speak about "molecules" I mean any atom or molecule. In other words, whether the cell needs some material intake from the external environment during the mitosis or not. If not, I consider that it has all the necessary atoms/molecules to fully complete the mitosis without any external need.


texts: Multiple start and stop codons in mRNA and pre-mRNA

texts:
I have a main question that will lead to further questions depending upon the answer.

In the process of transcription, will there be multiple start and stop codons in one sequence of pre-mRNA?  If there is, do they remain in the mRNA after splicing?  If they do, does that mean one mRNA has the coding sequence for the synthesis of multiple different proteins?

One last question: assuming a single mRNA has the sequence for synthesis of a single protein, is the stop codon always the final sequence before the poly-A tail?

Thanks in advance for your help and sorry for the mini rabbit hole.


texts: I have found this plant in my garden. I watered it, and now it is blooming. I have no idea what plant it is. Could someone help me to identify this plant? My geographic location is the Indian subcontinent.


texts:
I'm trying to find out why a prompt, severe, short pain is causing a stimulation of the vagus nerve. What could the physiological explanation be?

Is that because the pain is triggering the sympathetic system (Huge stress because of the pain), and directly after that the parasympathetic system is trying to balance it, but it's overreacting? and then the sympathetic system is going back to normal when parasympathetic stays high ?

Is there a physiologic explanation ?

Thanks


texts: I know that carbohydrates such as glucose are respiratory substrates for cellular respiration, but in this process, oxygen is also used to produce ATP so is it also a respiratory substrate?


texts:
I have studied that Diabetes Mellitus leads to kidney failure and that this is because of the damage to the blood vessels (especially the blood vessels in the kidney) due to high levels of blood glucose?

How do high levels of blood glucose damage blood vessels?


texts: What is the mechanism behind plants losing their leaves?

texts:
Do plants that lose their leaves (i.e., deciduous plants) do so because of external conditions (e.g., drought, cold), or because of an internal process?

Another way of looking at it: if you take a deciduous plant that loses its leaves during cold winters with long nights (e.g., Canada), and plant it in an environment where it is always warm and sunny (i.e., at the equator), would this plant continue to shed its leaves and re-grow them according to the seasons in Canada, or would it behave as an evergreen instead?


texts: How do animals handle light refraction in different media?

texts: For a human, when diving underwater, everything is blurry because of the water's different refractive index compared to that of air, which we are accustomed to. How do animals, like turtles, seals or penguins, handle that difference when changing the medium? Are they nearly blind at surface and can focus underwater or the other way around? Can they adapt to different refractive indexes on the fly? How?


texts: Are these statements about the effectiveness of condoms in preventing HIV transmission reconcilable?

texts:
Can the following statements be reconciled:

Condoms form an essentially impermeable barrier to HIV
Sexual activities other than penetration carry a very low risk of transmission
The consistent use of condoms reduces the risk of HIV transmission to about a fifth of what it would otherwise have been (source: Am Fam Physician. 2004 Oct 1;70(7):1268-1269 as summarized at aafp.org/afp/2004/1001/p1268.html)

Obviously the effectiveness of condoms is going to depend on them being used correctly, but surely they are not used so incorrectly that the effectiveness drops as much as these statements imply - assuming all 3 statements are correct, is there a more plausible explanation?


texts: What is this large beetle from Shirpur, Maharastra (central India)?

texts: I found this beetle in my college in Shirpur, Maharastra (central India). What is it? It is very large, and I have never seen it before. I believe it may be Titanus giganteus but I'm not sure.


texts: Western blotting: what common tweaks do you make to the protocol and why would you make membrane cuts?

texts:
I'm building an app which helps researchers plan out Western blots, record protocol tweaks and receive warnings in the app if:

you're trying to multiplex antibodies of similar molecular weight on the same membrane

you're using multiple antibodies on the same membrane for which different tweaks have been previously used leading to a "procedure conflict"... The app will suggest a membrane cut to allow the optimizations to be applied.

Are there other common tweaks that you make to your Western blot setup that you find yourself constantly needing to look up and/or forgetting?
I'm looking for a common use case to demonstrate the app's utility.


texts: Why draw blood from veins rather than arteries? Is it more convenient or safer?


texts: How do ascending neural pathways filter unimportant information?

texts: In school they told us one of the functions of the ascending neural pathways is to filter unimportant information. But the neural signal I know, is only a chemical-electrical chain of neurons. Is this filtering of unimportant information reminiscent of the gradual attenuation of the signal during the travel from the periphery all the way up to the brain? If so, how does that work?


texts:
I know that bacteria can become resistant to antibiotics.
Why do antiseptics like alcohols, PVP-I, still work on the strains of bacteria we have today? Shouldn't some bacteria have evolved to be resistant to them? I only hear about antibiotic resistance, so my assumption was that antiseptic resistance isn't a thing that happens.
What fundamentally differentiates antibiotics and antiseptics so that antiseptics are not resistance-prone?


texts: Evolution of diversity and extinction resistance

texts:
I saw a comment on an answer to another question that touched on an interesting topic:

  keeping diversity is useful for parameter exploration or to adapt to future environmental change

My initial thought was that evolution doesn't "know" about the future, so natural selection might decrease genetic diversity even if it meant dooming the species in the long term.

On the other hand, species that have low genetic diversity may be more likely to go extinct eventually.  So perhaps over time the surviving taxa are those that have evolved mechanims to "hedge their bets" against future environmental changes.

It's clear that some of the parameters that affect genetic diversity within a species (e.g. mate selection, mutation rate) are heritable, but it's unclear to me how the short-term processes of natural selection relate to the extremely long-term processes of speciation and extinction.  This gets into some of the same issues as group selection — how can natural selection, acting on individuals, lead to traits that benefit entire populations or clades?  (Perhaps this simply cannot happen.)

Has any work been done on the topic of extinction resistance or the evolution of mechanisms to create and preserve diversity within populations or taxa?

This is a big question so I don't expect a full answer here.  I'm just looking for some references as a starting point to learn more about this topic.


texts: Blood pressure difference while seated and laid down

texts:
My blood pressure readings differ a lot when I read them while seated and while I lay down on a bed.

I tie the strap in both cases to my left bicep and rest for a minute before noting the readings down.

For example, one reading I took was:

Seated: 130-85
Laying on bed: 115-75

These were noted down one after the other.

I am not sure if there should be this much difference in the readings and is this something to be worried about.


texts:
I want to use double stranded DNA linkers to physically bind two "things" together, by grafting ssDNA on each one of them and using DNA hybridization as the locking mechanism.

I do not expect the nature of the two things to be important for this question, but if it is, let's say I want to link a solid surface and a protein.

Let's say that my only constraint is that I want this crosslinking to be stable at 37°C.

There is a gazillion ways I could design the sequences, and pretty much anything above 20bp without massive self complementarities should work, in theory. But I don't like to pick bases randomly. So my question is this: is there anything I can look for, except for the two constraints above, to design a good linker sequence?

For example, if the melting temperature is 50°C vs. 65°C, I would expect the structure to be stable (infinitesimal dissociation constants in both cases). Would there be any reason to choose one over the other, except for maybe oligo synthesis price? For a given melting temerature, is there any difference between a long AT rich sequence and a short GC rich sequence?


texts:
Which book will give a brief account about B-cell development so that it covers two questions about the following cells:

Plasmablast
Plasma cell
Memory B cell
Marginal zone (MZ) B cell
B-1 cell
B-2 cell
Regulatory B (Breg) cell

Where do they lie in the course of B-cell development and differentiation?
What are their functions (outline)?

P.S. I need to know the development part in details rather than the functions.


texts: what kind of Pathway mediates nitroglycerin-induced relief from angina pectoris,please provide some idea...


texts: Should there be separate Ramachandran plots for an amino acid in different contexts?

texts:
I understand the nomenclature of the phi and the psi angles of the alpha-Carbon atoms in protein stucture, but I am confused by the Ramachandran plot. Each alpha-Carbon atom (magenta) makes two peptide linkages and has two corresponding neighbouring alpha-Carbons (cyan) and side-chains. I would expect the psi and phi values to depend on the interactions of these side-chains, so I would expect that for a single amino acid one would need a separate graph for every possible combination of neighbouring amino acids.

I am not clear whether this the case. The following graph (1) from Harper, Biochemistry, is for “many non-glycine residues from many proteins”. So, suppose a set of phi and psi is allowed for a right-handed helix (a value or data set taken from the plot) does it mean that it is allowed for any amino acid with any other amino acid? I woud expect an alanine adacent to an alanine to have a different interaction to an alanine adjacent to a bulky amino acid such as isoleucine.

I have also seen plots for specific amino acid and their allowed angles, such as that for proline (2), above. This suggests that the neighbours are not being taken into account. If this is so, why not?


texts: Is dysharmonia an actual disease or something only Oliver Sacks believes in?

texts:
In his book Musicophilia, Oliver Sacks discusses a case involving a woman named Rachel Y. who lost the ability to process harmony in a car accident. He then explains how this lead to simultanagnosia. He terms this loss of harmony "dysharmonia."

Is dysharmonia an actual medical condition or is this something Sacks just believes but has no real evidence for? My google fu didn't yield anything besides his book.  If it is legit, which regions of the brain are damaged and why are those regions in particular thought to induce dysharmonia?

Click here to read the case.


texts: Help identify this vertabrae found on Costa Rica beach

texts:
I was walking down tamarindo beach in Costa Rica today and came upon a really LARGE section of vertabrae.. I matched it against a crocodile a shark , whales, a horse, a cow, a snake even ... any ideas ? It naturally doesn't have another piece beyond the two transgressors bones ... I'm stumped... joined just to ask this... and also I think I found footprints in lava immortalized..  in the same area yesterday... thats a diff post tho w video .. I found the footprints in lava yest.. and went back today to see if I could find them again.. I didnt.. but found this instead... Note : I found another vertabrae about 1/5 its size about 15 ft away .. not sure if same animal

Any guesses?


texts: Do Osteichthyes fishes have any cartilage?

texts:
Higher vertebrates, such as mammals, birds, reptiles and amphibians have both bone and cartilage.

But do Osteichthyes fish (Bony fish) have any cartilage? Or do they only have bones?

I've searched the web but I could not find anything helpful.


texts:
I read in this 2012 research paper {1}:

  The aetiopathogenesis of CT [calcific tendinopathy] is still controversial, but seems to be the result of an active cell-mediated process and a localized attempt of the tendon to compensate the original decreased stiffness.

Has the cause of calcific tendinopathy been more clearly determined since then?

References:

{1} Oliva, Francesco, Alessio Giai Via, and Nicola Maffulli. "Physiopathology of intratendinous calcific deposition." BMC medicine 10, no. 1 (2012): 95. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3482552/ ; https://dx.doi.org/10.1186%2F1741-7015-10-95


texts: Can the Quarternary Extinction event be linked to the spread of mankind around the world?

texts:
Evidence is presented in a variety of media by Paul S. Martin as his 'Overkill hypothesis', particularly in Twilight of the Mammoths.

The internet describes this idea as 'controversial.' Other than the works of Paul Martin, what evidence has been presented supporting this hypothesis?


texts: What type of factor is practice of motor skills?

texts:
I recently asked a question about the cause of motor laterality: What causes motor laterality/ side dominance?
I understand that there can be genetic factors, epigenetic factors, or environmental factors. But in terms of continuous practice of motor skills, what type of factor will that be? Physical factors? Thank you!


texts: Identification of Bioluminescent Species in South Carolina Marshlands

texts:
I was in the brackish marshlands in South Carolina and the water was lit with short flashes of greenish bioluminescent light from a species that seemed to be floating in the current.  The lights seemed to be associated with a crackling noise as well but I'm not 100% sure that the light and sound were related as there were so many flashes going off at a given.

When I turned a flashlight on I saw some quarter inch long bugs moving in the water but the light was too bright to confirm that the bioluminescent light was coming from those bugs.


texts: In SDS-PAGE, why are the sample buffer and running buffer different in concentration?

texts: I'm currently trying to understand the concepts of SDS-PAGE. Every protocol I've read says to use 5X for sample buffer and 1X for running buffer, but I don't really understand for what reason? What are the negative consequences if I don't?


texts: Why does regular bread yeast fail to thrive in pond water?

texts:
I thought I'd try adding regular yeast to water taken from my 75 gallon pond, with the idea that the yeast would be a good "bottom of the food chain" kick start to feed the little beasties, along with warmth and light, to allow the creatures to multiply faster than they would in the pond, to be added back the pond as feed. But to my surprise, the yeast won't grow in the pond water, at least, not like when you make bread with it. I've tried adding sugar, molasses, and "proofing" the yeast, but each time, the yeast does not thrive. Is something eating it as soon as it starts to grow, or is something using a nutrient it needs, or what?
The pond is established, with lots of plants, only a few fish, and ammonia levels are 0 ppm. It is an (apparently) thriving ecosystem. My question is, why won't yeast grow and froth up in that water?


texts: Laparoscopic surgery: Why did the gas cause pain in my shoulder, and how did it escape my body?

texts:
I recently had Laparoscopic surgery, and the nurse told me I would experience pain in my shoulder and burping as the gas escapes my system. I looked up a bit of information on the "pain in my shoulder" claim, and its due to the CO2 gas irritating my phrenic nerve. So my first question is:

Why was the pain only in my right shoulder when there is a right and left phrenic nerve? Is it common for patients to experience pain in one or both shoulders? If CO2 causes pain/irritation, why not switch to another gas?

My second question revolves around the burping and the gas escaping my system. Basically, how? How is it that gas in my abdominal area escapes through my mouth? Is it through some absorption mechanism?

Thank you!


texts: How is the fermentation in Hákarl different from putrification, at a biochemical level?

texts:
My understanding of the types of microbial action in food:

Curing: The "non-action" where meat is essentially rendered too salty for much of anything to grow. Sometimes fermentation is used as well, but my understanding is that carbohydrates are added if so (see below).

Fermentation: This is anaerobic degradation of carbohydrates. Yeast in bread and beer comes to mind, as does cheese. The acid preserves food. Odors are generally sour.

Putrefaction: This is anaerobic degradation of proteins. This sends food to the trash bin, preferably in a tightly sealed container.

Aerobic digestion: This is basically compost. The pile needs access to air to function and can generate considerable heat. It leaves very little organic material behind.

Meat has very little carbs, so how is fermentation functioning Hákarl? What stops putrefaction?


texts: Are specific primers or detectors, or both, used in COVID-19 tests?

texts:
I am trying to learn about the rRT-PCR testing procedure used to test for COVID-19, but I am slightly confused on one point. Are highly specific primers used with a non-specific detector, or are highly specific detectors used, or are both specific primers and detectors used? Some of the sources say that multiplex PCR is used, which indicates a specific detector, but as I am still a beginner on the subject, I am not sure. I would also really appreciate it if somebody could also point to a source that details the some of the testing procedures.

Thank you


texts: How was the origin of CTVT parasitic cancer determined?

texts:
The wikipedia article on CTVT says that the tumor cell has 57-64 chromosome while a normal dog has 78 chromosomes. Similarly while all chromosomes in dogs except the X and Y chromosomes are acrocentric, many of the CTVT chromosomes are sub-metacentric or metacentric. Reference is given for the data in Wikipedia though a subscription is needed to view the referred articles themselves, so I was unable to confirm the data. (Wikipedia is sufficient for me, though popular opinion seem otherwise)

In addition there seems to be numerous (in the order of thousands) differences in sequences.

  Their study showed that the cancer cells all originated from a common ancestor cell, not from the dogs themselves. Comparisons of the cancer DNA with dog DNA from reference samples held by the US Kennel Club and Crufts showed that it most likely originated at least 250 years ago from a wolf or an "old" Asian dog breed such as a husky or Shih Tzu, and spread like wildfire thereafter.

This was taken from Riddle of Infectious Dog Cancer Solved.

How is the conclusion arrived at in cases like this in general? What percentage / degree of genetic similarity is needed to identify something as belonging to a specific species?
How was the conclusion arrived at in this specific case? (I know I am greedy!)


texts: What causes the opaque green colour in Lepidoptera?

texts:
Link here to what I mean by 'opaque' colouration on the insect, the colour intensity remains constant despite changes in light intensity and angle (not shown by the picture but the moth exhibits this in the field). This is different to 'metallic' colouration on other moths like the Forester moth (image here), where the colour intensity changes with light angle and intensity.

Through reading R.F. Chapman's book ('The Insects:
Structure and Function'), I know that metallic colours are caused by interference patterns produced by the micro structure of the scales, the book says this is how most higher frequency colours are produced, including green in this category. Obviously I've looked for pigments that could give this colour but I haven't found anything that is produced in insects.

So my question is: Is there a pigment that gives this colour in the insect and if so, what is it?


texts: How to create a 3D density map of a system of varying number of particles?

texts:
I have a time-dependent system of varying number of particles (~100k particles). In fact, each particle represents an interaction in a 3D space with a particular strength. Thus, each particle has (X,Y,Z;w) which is the coordinate plus a weight factor between 0 and 1, showing the strength of interaction in that coordinate. Here http://pho.to/9Ztti I have uploaded 10 real-time snapshots of the system, with particles are represented as reddish small dots; the redder the dot, the stronger the interaction is.

The question is: how one can produce a 3D (spatial) density map of these particles, preferably in Matlab or Origin Pro 9 or ImageJ? Is there a way to, say, take the average of these images based on the red-color intensity in ImageJ?

Since I have the numerical data for particles (X,Y,Z;w) I can analyze those data in other software as well. So, you are welcome to suggest any other analytical approach/software

Any ideas/comments are welcome!


texts:
I caught this insect in my house.
It has 6 legs, long antennae, 2 pairs of wings and is dark brown.


texts:
These red bugs can be found in hundreds in our locality in Bangalore, India.

They are just about 3.5 cm and have these white (or maybe pale yellow) tips on their antennae.

Can someone identify them and suggest a link where I can find substantial information on their morphology and general behaviour?


texts: Why do pink rain lilies flower only after rains, and not from being watered?

texts:
We have pink rain lilies (Zephyranthes carinata) in the garden. In my personal experience, I've found that they always flower, without exception, shortly after rains. However, there are roughly ten totally dry months each year. During this time, even though I water them regularly with well-water, they never flower. I've tried copious amounts of water, and frequent watering, but to no avail. They seem to depend on rain.

The rains here come at different times each year. We just had a totally unexpected rainstorm in May, causing them to flower. We are inland in southern India. It's very hot here, and the climate is quite dry in the periods when it's not raining.

How can this be? What's going on inside the plant, biologically speaking? How can it "know" whether it's getting rain water or well water? I'm looking for a description of the biological processes inside the plant which cause these different responses to rains versus watering.

Also, (minor, secondary point) is there any evolutionary reason why a plant would develop this trait?

I prefer answers that cite their sources for the information.

Edit: A user added some quite relevant personal observations in the form of an answer. I'm adding it here, as the observations are quite relevant to the question.

  I live in central India which is marked by a heavy rainy season from mid June to September and almost dry rest of the year. This behavior of rain lilies has been a mystery to all of us for generations.

  No matter what season, what temperature, the lily bush will give you
  at least one bloom even if rains for a mere few minutes. Rest of the
  time, any amount of watering does not help. I've seen the plant bloom
  with just a bit of drizzling in summers when temps cross 40 degrees
  celsius.

  Whereas, a friend is growing them in a pot in a water lily pond.
  Basically, in shallow water where the rain lilies are just dipping
  their feet in water all the time. So basically, for a large portion of
  the year, the plant is meeting the low temperature, high water criterion.
  It doesn't work. The plants bloom only and only when it showers.

  By the way, the behavior is not limited to pink rain lilies. It's the same with yellow and white lilies.


texts: What bee do I have nesting in my front yard

texts: Can someone help identify this bee? Its living in a hole between a boulder and a retaining wall. Our tree that is above it is now bleeding sap so I'm worried about the tree. Pest control wont come because they think it's a honeybee but I doubt that's what it is. I don't hear buzzing and one bee leaves at a time. They are not aggressive. The abdomen is black with yellow stripes.


texts: Role of the pupil response in night vision

texts: What are the things that affect the reaction time of pupil light reflex? What I mean to say is, if you are in a bright room, and the light suddenly turns off. The time you spend to see things in the room (i.e.., night vision) is the reaction time.


texts: Transport mechanism in absorption of monosaccharides in small intestine

texts: In the cell membrane of the intestinal cells, there is a mobile carrier protein called Sodium  Dependent Glucose Transporter(SGLT1).It transports glucose and galactose to inside the cell using energy.The energy is derived from sodium-potassium pump (Primary Active Transport).How it is possible cause we need energy in Na-K pump too ?


texts: What prevents the translation of the negative strand of negative-sense viral genomic RNA?

texts:
Some RNA viruses contain negative-sense RNA. Then they use this negative-sense RNA to make positive-sense RNA that is then translated into protein.
My question is what prevents the translational machinery of the cell translating the negative strand into protein? Is there some signal that indicates that this is a negative strand?


texts: Please help me to identify this red worm

texts:
I found bunch of red worms coming out of sink.
It is rather unusual to find an overwhelmingly large number of worms. It doesn't seem like earthworm or horsehair worm. I don't know much about the worms though.

Could anyone please identify it for me.?  Notable features are

Dark red in color.
Has  a hook like structure at its rear end.
Moves in both directions front and rear.
It shrinks when it dwells in water.


texts: Difference between thylakoids and lamellae in a chloroplast?

texts:
I'm slightly confused as to the difference between thylakoids and lamellae. My understanding was that thylakoids are 'discs' that are stacked into grana and there is a membrane between the grana called the integranal lamellae. However in my text book it says that 'the inner membrane is folded into lamellae, which are stacked up like piles of pennies. Each stack of lamallae is called a granum.' This sounds to me like the description of thylakoids.
It later says 'grana are stacks of flattened membrane compartments, called thylakoids'...

Could someone clarify this?

Thank you in advance :)


texts:
The number of amino acids in a protein is important to predict their size. I used coding DNA sequence (CDs) to predict the average of the protein size of E.coli k12 from a sample provided by the seqinr R package. The size of each sequence is stored in variable x.
I used two histograms to fit the distribution of this variable and their logarithm.

I suggest that the log linear distribution is more reasonable.The average E can be calculated then:

E1=mean(x)/3

E2=exp(mean(log(x)))/3

Which average do I have to use?
Is there a correlation between the base composition and the predicted average?


texts: What is the difference between "gene delivery" and "gene therapy"?

texts:
What is the specific difference between gene delivery and gene therapy?

As far as I understand, gene delivery is the first step of gene therapy, but where does gene delivery end and gene therapy begin?

Does gene therapy necessarily imply that the host DNA is itself changed, or is it just that there is "extra" DNA floating around with the host DNA that also gets replicated?


texts: Does electricity cause damage on a cellular level?

texts: As I understand it the mechanism of death when a mammal is electrocuted is that the current disrupts the SAN/AVN in the heart causing it to fibrilate or arrest.  That's on a macro scale, however.  What damage, if any, does electricity cause on a cellular level?  I've noticed some sort of moss or lichen growing on the third rail of the train lines so I'm aware that they must be able to cope with the current, do they have adaptations ot allow this or is it just that they are not connected to the earth?


texts: Are the asymmetrical positions of owl ears consistent across species with this trait?

texts:
While at a raptor speech a while back ago the naturalist mentioned that owls have offset ears. One ear is located higher in the skull than the other. This is supposed to help the owl detect the location of prey due to the tiny time difference in which the sound reaches each ear. After doing some more research online, it seems that the offset ears are primarily found in owls that are nocturnal hunters. Specifically, I have found that Barn Owls left ear is higher than the right.

Barn Owl (Tyto Alba)-www.robinsonlibrary.com

Are the ear openings are always higher on the left for each species of owl that has asymmetrical ear openings? I would guess that they are predominately the same unless this characteristic had evolved in more than one instance.  Any additional information would be appreciated.


texts: Guide to learning about Population biology / ecology / dynamics for a non-Biologist

texts: I'm an applied mathematician who works in the field of feedback control systems but has been becoming interested in looking at population biology (e.g. Lotka-Volterra, Mathusian growth,etc.) from a mathematical feedback and systems theory standpoint. Since I know almost nothing about biology save for a poor frog I nearly threw up on while trying to dissect in High School, I wanted to ask this community if anyone could provide me with some materials that give a good overview of the current state of this field.


texts: How do apiarists cultivate homeycomb without nicotine or a smoker?

texts: I don't see a better stack site for this so I'll just post it here. I remember an apiarist I met saying they cultivated honeycomb without a smoker or anything like that, but I never asked them how. Figured it would be interesting to ask if there is any consensus on how one could do that without bees swarming or anything like that.


texts: Why does water stress lead to alkalinity of xylem sap in plants?

texts:
I was reading this book: Plant Physiology and Development, Sixth Edition by Lincoln Taiz, Eduardo Zeiger, Ian M. Møller, and Angus Murphy when this doubt came to my mind. Abscisic acid, the stress hormone, works to prevent water loss from a plant. Its mechanism of action requires the xylem sap of the plant to be alkaline. I can't figure out how water stress in the plant body causes alkalinisation of the xylem sap. The section in the book stated as follows:-

  During the early stages of water stress,however, the pH of the xylem sap becomes more alkaline,increasing from about pH 6.3 to about pH 7.2.
  Stress-induced alkalinization of the apoplast favors formation of the dissociated form of abscisic acid, ABA–, which does not readily cross membranes. Hence, less ABA enters the mesophyll cells, and more reaches the guard cells via the transpiration stream.

I'd be grateful if anyone out there can help.


texts: Identification of a young tree in the alpine region of southeastern France

texts:
I have a young tree growing in my backyard (in Grenoble, France), and I was not able to identify it, despite searching with many identifier tools.

It's 2 years old now and must be 2 meters high. It has a grey trunk, its leaves grow on brown/red stems that protrude irregularly from the trunk.

The leaves are pointed, gently serrated, covered with a light fuzz, with a distinct lattice of veins.

Could you help me identify it?


texts: Why half of the protein is saturated when [L] =Kd

texts:
let's suppose the following reaction:

At equilibrium we can calculate the Kd (Dissociation constant) using the following formula:
Kd = [P][L] / [PL]  or kd / ka
We can then use the Hill equation to calculate the fraction of binding sites which are occupied:
occupied binding sites = [L] / [L] + Kd

  When [L] euals Kd, half of the ligand binding sites are occupied (Lehninger principles of biochemistry)

Why is this true? This would mean that at equilibrium half of the binding sites are occupied?


texts: Introducing evolution into the Hodgkin-Huxley equation

texts:
How would the Hodgkin-Huxley equation change when the geometry of dendrites and axons are introduced?

Also can we model a situation of membrane activity during the corse of evolution, hence the equation would be subject to a periodic function ad it varies with time?

Taking the example of membrane transmission of electronic signals(in humans), can we model the change in conduction of the e-signal through the axon as its speed and geometry changes with evolution?


texts: Interesting Insect, possibly a beetle (Northern Indiana)

texts:
I happened across an interesting looking insect, that I've never seen before.  In Northern Indiana, late spring around 5 PM CST.  I tried a reverse image search, with no luck.  It is approximately 3/4 inch long.

Any ideas?


texts: Identify chromosome location from gene nucleotide or amino acid number

texts:
I'm sure this is a basic question, but I couldn't find an answer anywhere. Let's say I'm provided with the location of an amino acid or a nucleotide (for example, which lists the location as the ACADM gene, 985A>G (the nucleotide polymorphism) and 304 as the amino acid mutation (from Lys>Glu)). How would I go about now identifying the exact position of this on the chromosome? Eg: Chromosome 1, location 76123456?

Currently the only way I can think is to manually count 304 amino acids, or 985 nucleobases, from the start of the gene where the start location is listed. However this isn't practical. I downloaded some software (IGV & GenomeViewer) and can't see a way I can view the actual amino acid or nucleobase number from the start of the gene.


texts:
I've sequenced two genes of 15 dogs for SNP analysis. the chromatograms of one gene looked perfect but the ones of the second gene didn't look as good. To be precise, the chromatograms of one exon looked relatively good with only a few spots where the bases seemed unreadable. But the chromatograms of the second exon were full of that. So there must have been an error somewhere and my question is where this could have happened.
My hypothesis is that I simply made a mistake during the mixing of the chemicals at some point.

Further useful information: The error must have happened befor the first pcr since i checked the pcr product with a fragment analyzer and the bands were only barely or not visible. Additionally, I noticed that many imprecisions seen in the chromatograms were only found at either the forward or backward strand.

Here is an image of several of the chromatograms of the exon that didn't work:


texts: Is it true that ethanol can have some positive effects?

texts:
I recently was reading this inforgrafics about excessive alcohol use. It is written:

  No one should begin drinking or drink more frequently based on
  potential health benefits

I am surprised. Is there any potential health benefits of drinking alcohol?

To check this information, I made a little research and found this article of the Medical Daily: 7 Health Benefits Of Drinking Alcohol. Apparently, a moderate alcohol consumption (no more than 2 drinks a day for a men) can lower the risk of cardiovascular disease, lengthen the life, decrease the chances of demantia and diabetes, ...

But, for all of these facts, only one study is provided. So, I want to know if it is a well established fact that alcohol can have positive effects on health. And, if so, what is the corresponding dose to get these benefits?


texts: If I workout, will this inherited trait (of being stronger) not be passed down to my offspring (Lamarck's theory on evolution)?

texts: I'm a student in biology and just recently learned about Lamarck's theory on evolution and how it has been disproved. While I understand that you cannot alter your genes, I'm still having a hard time understanding some parts of it, mainly how inheriting strength (such as working out) will not be passed down to my offspring. If someone was obese, exercised to the point of no longer being obese, will this person's offspring still start off as obese?


texts: Why do people with Down syndrome get fewer cancers?

texts:
I'm coming across some conflicting information regarding the correlation between cancer incidents and trisomy 21. I read a report from nature that discusses how Downs are only a tenth as likely to develop cancers, but at the same time are 20x more likely to develop certain B cell malignancies.

One of the more prominent findings show that a regulator of angiogenesis, DSRC1 plays a significant role.

What I'm trying to find out is what gene(s) on 21 contribute to the associated risk for lymphoma?

And does there exist a good list of those genes on 21 that suppress or enhance tumor genesis.


texts: Is there any evidence that humans have faced extinction before?

texts: Have we as a species faced extinction in the past? Resulting in a 'population bottleneck'?  If so, what genetic evidence is there of this occurring?


texts: Prenatal hyperkinetic dysfunction and its effect on endurace

texts:
Do people with an hyperkinetic dysfuntion have a better endurance?  Are they fitter in cause of their Dopamine-overdose or any other reason? I have a case, where someone does not do any sports, but has an endurance way better than most of others who does no sports. He even can compete with some amateur athletes.

Just for comprehension: He does not eat well, sits most of the time (during work, at home), does not do any other activities except eSports (onlinegames).

Maybe someone has an answer, at least I hope you have.


texts: How do nasal and aural passages connect?

texts:
I have had a bad flu with a lot of congestion.  My husband suggests a way to clear my stuffed ears is to pinch my nose shut then blow air through.  Sometimes that helps, sometimes there's just too much congestion.
What is happening exactly when I do that?  I've looked at diagrams of nasal and aural passages, but it's not clear to me what's happening when you block the nasal passage and then blow air through.  I would like to know exactly what the passage of air/fluid is.
Also, is it a bad idea to do it?
Thank you.


texts:
I know frogs start croaking at the same time to attract a female.

Why do they all stop at the same time?


texts: How to identify a coiled coil from the amino acid sequence?

texts:
I was wondering, when we have an amino acid sequence, is it enough to check whether the positions a-d correspond to hydrophobic amino acids in order to say whether it can form a coiled coil structure? Or would we need to make sure the other positions are not hydrophobic too?

All help greatly appreciated.


texts: Biological & Evolutionary Reasons for Palm (Bi)Symmetry

texts:
The fingers of the human palm exhibit a (bi)symmetrical pattern with regards to their size, in the sense that the thumb and the pinky are almost the same size, and the same holds for the index and ring finger. I was wondering what the biological imperatives and/or evolutionary advantages behind this physical characteristic are.

The only rationale I personally am able to come up with is that this particular arrangement might be optimal or ideal for grasping, handling, and manipulating objects, but am unsure of its truthfulness, and, even if correct, I would still be interested in exploring other possible avenues.


texts:
I have heard that rattlesnakes are developing stronger venoms causing more people each year to die from rattlesnake bites.

But why would a snake that is already very venomous need to develop stronger venoms? I mean for the venom resistant ground squirrels couldn't the snake just wait longer or maybe strike more than once before it eats?

And I could see this going to venom overload in the next few centuries. If rattlesnakes keep developing stronger venoms at the pace that they are then rattlesnakes could become as venomous as a cobra or worse. Along with that it might rattle less and less until it just stops using the rattle.

Is is because of the fact that we are developing stronger pit viper antivenoms(mainly by injecting rattlesnake venom, copperhead venom, and cottonmouth venom into an animal with a stronger immune system like a horse and after a while, getting the antibodies needed for the antivenom) that rattlesnakes are developing stronger venoms?


texts: As electrons are moving through the ETC, how is ATP produced for the active transport to even happen?

texts: A lot of websites aren't being specific and they are just saying that when electrons move from a high to low energy state during the ETC, "energy" is being released and that energy is used to pump (active transport) H+ ions through the membrane. I want to know more. Isn't ATP formed by adding a phosphate to ADP? If so, where do electrons moving through the ETC get that phosphate from? BTW, I'm not talking about ATP synthase, because you need H+ ions for ATP synthase and I'm not understanding how those H+ ions are being actively transported through the membrane in the first place.


texts: I'm not talking about single celled organisms, but actual cells in your body. Is there any evidence that they can learn to, say, navigate an environment or avoid an aversive stimulus like an animal could? Is their behaviour understood well enough to say that it's entirely mechanistic, or are there things we still don't know?


texts:
I´m using water container placed on a radiator to humidify room air. Someone might argue that it is a perfect nest for bacteria. I have to put copper coins into the water to kill the bacteria.

I would like to do an experiment, have two similair containers filled with water one with copper coins, the other without them.

I would like to compare how many bacteria are living in those containers, how can I do that? (in home conditions)


texts: Is the "Manhattan Ant" a new species; still only found in Manhattan's Upper West Side?

texts:
I've stumbled upon the viewing.nyc article Upper West Side Has Its Own Ant Species Dubbed the "ManhattAnt" which says:

Columbia University biologist Rob Dunn has discovered a unique species of ant living between 63rd and 76th streets along Broadway on the Upper West Side of Manhattan. Dubbed the "ManhattAnt", the ants have a higher concentration of carbon in their bodies, indicative of a high corn-syrup diet, likely from eating trash and discarded street food.

Biologists stumbled upon a new species of ant in the Broadway medians at 63rd and 76th streets […] The ant looks like it hails from Europe, but so far the scientists have not been able to match it with any of the approximately 13,000 species of known ant. “It’s new to North America, and we believe it’s new to the entire world,” biologist Rob Dunn, whose team discovered the insect, told the Post. The ant doesn’t have a scientific name yet, but it’s fondly nicknamed the “ManhattAnt.”

and references the Simthsonian Magazine article NYC Has Its Own Ant, the “ManhattAnt” with the subtitle:

A new ant species joins a menagerie of other creatures cut off from their kind in isolated patches of urban green in NYC

A "new species" is not the same thing as a "creatures cut off from their kind in isolated patches of urban green in NYC"
Question: Has the "Manhattan Ant" or "ManhattAnt" turned out to be a new species, and is it still only found in Manhattan's Upper West Side?


texts: What is the consensus in the scientific community over COVID-19's mode of transmission?

texts:
I've read from many news and scientific sources that COVID spreads primarily through respiratory droplets, but I've also read multiple sources that have said we don't entirely know yet. Is it fomites, droplets, or aerosols? Is it some combination? Do we have a complete understanding of it?
With how infectious the B117 variant appears to be, it seems like it would spread through aerosols, since most other infectious diseases that are very contagious tend to spread through aerosols, like measles, tuberculosis and varicella. If that's the case, why do so many sources keep claiming that it's through droplets? I've also read an article on the Johns Hopkins website that suggested the scientific community was initially wrong about the mode of transmission for tuberculosis, so is that possible for COVID?
Thank you!


texts: Is "Retinal Glial Cells Enhance Human Vision Acuity" creationist propaganda?

texts:
The paper Retinal Glial Cells Enhance Human Vision Acuity is profusely quoted by creationists as "proof" of the "perfect design" of the human eye.
The paper is about biology but published in Physical Review Letters (open access, click PDF). Is it generally accepted as legitimate science, though cited by creationists, or is it thinly veiled creationist propaganda?


texts: Could total 2020 flu deaths be low due to Covid19 countermeasures?

texts:
A working assumption is that Covid19 countermeasures will also reduce seasonal flu transmission and mortality.

Could this effect be so large that the 2020 total global deaths from both causes will be lower than the annual expected deaths from seasonal flu alone ?

I understand global seasonal flu mortality is around 40k/month


texts: What is the motivation behind the AAAAGCAUAU GACUAAAAAA of the mRNA SARS-CoV-2 vaccine when encoding its polyadenylated ending?

texts:
The very end of mRNA is polyadenylated as usual, but the BNT162b2 vaccine ends the following sequence, as denoted in this article:
                                     ****** ****
UAGCAAAAAA AAAAAAAAAA AAAAAAAAAA AAAAGCAUAU GACUAAAAAA AAAAAAAAAA
AAAAAAAAAA AAAAAAAAAA AAAAAAAAAA AAAAAAAAAA AAAAAAAAAA AAAA

This is 30 A’s, then a “10 nucleotide linker” (GCAUAUGACU), followed by another 70 A’s.
What is the reason for this design choice?


texts: Reaction centre in Photosystems of higher plants

texts:
In photosystems of higher plants, there are about 250-400 pigments (number wise) in a particular photosystem. Out of which,approx 170-180 pigments are of chlorophyll a molecules. And any one of them behaves as a Reaction centre in a photosystem.

My question is:

What are the factors and laws which decide which chlorophyll a molecule will work as a reaction centre?
What's the difference in chlorophyll a molecules present in reaction centres of PS I and PS II since they have different threshold energy. Is there any structural difference?


texts: How many different protein coding genes are in the Human Biome?

texts:
There are approximately 20k protein-coding genes found in the human genome. This number is presumably very small when considering all the genomes found in the diverse microbes associated with the human body.

Is there an estimate for the total number of protein-coding genes found in human microbiome?


texts: Calculate signifficance of SNP in specific trinucleotides

texts:
So, I have calculated the frequency of all SNPs (single nucleotide mutations) in some samples and have also found the nucleotides on the 3' and 5' sides of the mutated nucleotide. So I have a list of 192 possible permutations like this one:

AAA -> ACA 43
AAA -> AGA 35
AAA -> AAA 134
.
.
TGA -> TAA 345
TGA -> TCA 25
TGA -> TTA 97
.
.

What is the statistical approach to show that a particular set of 4 of these mutations is significant?

I have little knowledge in statistics so I welcome a for-dummies explanation!


texts: Do other animals have similar blood types to humans?

texts: I am interested to know if there are any animals having blood groups similar to human blood groups? Is it possible to transfuse blood between humans and those animals?


texts: When endothelial cells in blood vessels (arteries or veins) are damaged, does atheroma form first or blood clot?

texts:
I have learnt from Khan Academy's video on atheresclerosis that when the endothelial cells of an artery are damaged, atheroma forms at the site, and if the atheroma’s fibrous cap is ruptured, thrombogenic material is released from the atheroma, causing a blood clot. Having read other articles on this issue, this phenomenon is known as the atherothrombosis. And I believe that the fact that atheroma is formed before thrombosis is because thrombogenic material isn’t released when endothelial cells are damaged; thus cholesterol deposits in the area to form atheroma first.

However, in another video, when endothelial cells in blood vessels are damaged, platelet activation occurs due to the exposed collagen, and thrombosis occurs. Why is it that blood clotting occurs first instead of atheroma?

I have also learnt from my other question on Biology StackExchange that hypoxemia in the valve pocket of the large veins can cause endothelial damage that triggers the clotting cascade.

Therefore, I am confused as to which of atheroma or blood clot is formed first when endothelial cells are damaged; and if either one is formed first, why is that so? I’m certain that after a blood clot is formed, atheroma won’t be formed as I’ve not found any article that supports this sequence.

References:

https://www.khanacademy.org/science/health-and-medicine/circulatory-system-diseases/coronary-artery-disease/v/atherosclerosis
https://www.youtube.com/watch?v=R8JMfbYW2p4
https://academic.oup.com/eurheartj/article/25/14/1197/509341
How do veins's valve pocket sinus tend to become hypoxic?


texts: Are there any known plesiomorphies of all living mammals relative to a newer trait state in all living reptiles?

texts: If I understand how a "trait" is defined, a turtle's shell is a synapomorphy relative to mammals and the common ancestor of living amniotes. The same would go for a snake's limblessness, etc. But are there any synapomorphies all living reptiles have in common relative to an older trait state found in most or all modern mammals? Traits modern mammals share with the common ancestor of living amniotes which reptiles do not also possess?


texts: What is the state of automated quantitative analysis?

texts:
Quantitative analysis of microscope images is essential for many types of studies, but the techniques used most often are very labor-intensive. I have been able to find some literature about using computers to perform the analysis, but do not have a good picture of the state of the art.

Is there a good literature review on the topic?
Is there much use in practice which I have not yet seen?


texts: Why is the ability of a virus to get crystallized considered as a "Non living feature of a virus"?

texts:
My book states that the fact that :"Viruses can be crystallized" is a proof of their "Non living character"
Does that mean living things cannot be crystallized? If yes, why is that so?


texts:
I am having trouble visualizing/grasping the necessity of alpha-gamma co-activation. My understanding is the following:

When an external load causes stretching of the sensory muscle spindles, the 1a afferent fibers travel via the DRG and synapse on both alpha and gamma motor neurons in the anterior horn of the spinal cord. The alpha motor neuron then relays an efferent signal to the extrafusal muscle fibers and induces a contraction. Almost simultaneously, the gamma motor neuron relays an efferent signal to muscle spindles, causing the contraction of the intrafusal muscle fibers at their polar regions, and stretching at their equatorial regions. The stretching of the equatorial regions is what causes the 1a sensory fiber afferents to relay signals to the spinal cord.

Herein lies my problem. If muscle spindles can only relay their afferent signals to the spinal cord AFTER gamma activation, but gamma activation requires muscle spindle afferent signals, wouldn't this be a catch 22? Also, I read from a few sources that gamma activation, while almost simultaneous, occurs after alpha activation. Wouldn't the converse make more sense as gamma activation would trigger higher alpha firing frequency?

I hope my question makes sense. This is my first time making a post on this forum so I do apologize if the syntax of my question is not in accordance with proper question formatting.


texts: How does hydrophilic and/or hydrophobic components of polysaccharides influence their 3 dimensional conformation?

texts:
It is my understanding that polysaccharides are insoluble in water. Does this mean they are hydrophobic? Beyond being insoluble in water how does this affect their 3D structure?

Thanks!


texts: Does intelligence depend more on environment than on genetic factors?

texts:
Many have argued that the test of IQ is simply a test of language. The application of the test consists of asking a number of questions. The person should understand the question presented to them and should be able to answer the questions properly. If a person does not understand the question or do not know to answer or give a wrong answer it results in a negative point.

is there a genetic component in this equation?


texts: What hair color will result in someone inheriting both blond and ginger genes?

texts:
Both the genes for blond hair and ginger hair are recessive, so they need both parents to give the same gene for it to take affect. What happens when a person has 1 copy of a recessive gene and another copy of a different recessive gene.

They don't have enough of the recessive genes to have either blond or ginger hair, but they don't have a dominant gene to "take charge"?


texts: What happens when the congenitally blind brain receives visual input?

texts: If a congenital blind person gets eye sight (either hypothetically, or in the near future due to advancements in technology), will their brain be able to handle that information, or will it become overloaded?


texts: Can action potential generating ion channels only be understood as assemblies of membrane proteins (and not as single proteins)?

texts:
I always believed to have roughly understood how voltage-gated ion channels and the creation of action potentials work: as and by single (or non-interacting groups of) membrane proteins, that behave somehow non-linearily by intrinsic means, each by its own. But suddenly I doubt.

Might it be the case that some of the non-linear dynamics of ion channels and the generation of action potentials cannot be understood when looking only at single ion channels as proteins? Or is it like Wikipedia says:

  A voltage-gated ion channel is a cluster of proteins embedded in
  the membrane.

This means, that some of the non-linearities only occur when many membrane proteins (presumably in a fine-tuned mix of different types) interact?

Maybe only then some features of ion channels can be understood:

Action potentials are always of the same size, independent of the voltage (or current) that is applied/injected (which would be hard to understand for single membrane proteins).
Ion channels can exhibit many different firing patterns, which depend on intrinsic emergent mechanisms of assemblies of membrane proteins.

If this is so, one must be very careful when talking or reading about voltage-gated ion channels, because depending on context sometimes single membrane proteins are meant, and sometimes complex assemblies of non-linearily interacting proteins.


texts: Why does some skin hold perfume longer than others

texts:
I was wondering my girlfriend and I used the same perfume for a while and we sprayed the same place. And after a day her skin still smells nice while mine smells normal.

Will different types of perfume hold longer on different skin types?


texts: Do repeated freeze-thaw strip nutrition from vegetables/food?

texts:
Some of my family and friends seem to believe that vegetables/food should be subjected to as few freeze/thaw cycles as possible. The rationale put forward is that each such cycle reduces nutrition (sp. nutritive?) value, and accelerates rot.

I'm skeptical; Do repeated (sp. repetitive?) freeze/thaw cycles strip nutrition from vegetables/food?


texts: Which fishes produce alarm signals to warn other group members about in coming predators

texts:
Atlantic Goliath Groupers are fishes which produce unique low frequency sounds to mate and when approached by predatory fish . The sounds produced when approached by a predator (or even a scuba diver) are different from those produced whilst mating.

The problem is this fish is found only in the Atlantic.  I'm specifically looking for fishes in the Indian ocean . Thank you for ur time :)