texts:
Splicing is a modification of pre mRNA when all introns are removed and exons are joined.
What is a splice junction pair? It is two exons which connected together?


texts: Is pulse rate measurable in the capillary bed and venous vasculature?

texts:
Pulse rate is easily felt when gently pressing the arteries in the wrist or neck region (Fig. 1).

Fig. 1. Feeling the pulse at the radial artery. Source: Wikipedia

Arteries supply the thin vasculature in the capillary bed where the blood flow encounters a large increase in resistance due to the narrow vasculature and blood flow is reduced, albeit the pressure may still be relatively high. The capillary bed, in turn, feeds the venous system (Fig. 2), characterized by a low blood pressure and relatively slow and continuous blood flow. This steady, slow blood flow is apparent during blood sampling procedures from the veins in the arm, where I have never noticed any pulsatile flow by visual observation (anecdotal evidence, but quite representative I'm sure).

Fig. 2. Blood vessels. Source: Aruba trial.

Is there an observable/measurable pulse in the capillaries and veins, or is blood flow continuous in these vessels?

PS. This question was re-formulated based on a deleted question posted by @laggingreflex and credits go to OP.


texts: What's the biggest obligate anaerobic organism discovered till now?

texts: Beside many anaerobic single cell organisms, there are some annelid worms that are obligate anaerobic at least in their early development stages. Probably, due to low concentration levels in nature, some of the other respiration methods (like uranium or iron reduction) can limit the maximum size an organism will grow. Given the lower energy level extracted compared to the oxygen respiration, what size limits enforces the sulfate, sulfur or methanogenesis respiration? What's the biggest discovered organism, extinct or alive, that is obligate anaerobic?


texts: Does a reproductively successful male have the same genetics as a reproductively successful female?

texts:
Evolutionarily, using humans as an example, it would make sense that a successful female would produce successful male offspring. If a successful female produced male offspring that weren't successful, the female also wouldn't be successful by definition and would, through evolution, stop being desired by males. Therefore, females are selected for by their ability to produce successful males and thus successful male genes must be the same as successful female genes?

However, I've heard that in humans today, males don't like rich females while females like rich males. Also, from what I've read, lascivious females used to be looked down upon in the past while lascivious males weren't. Females and males also played very different roles in society. Also, successful males often don't spend much time taking care of children and spend more time making them, while successful females spend more time taking care of them. This suggests that successful males are genetically different than successful females? I'm an amateur in biology, so correct me if I'm wrong.


texts: How does a virus reach its host, it is always passive?

texts:
We know that viruses are non motile and cannot metabolise, and that it enters the host cells via binding to the receptors. But how exactly it reaches the host

(that is, how it go from the transmission medium (e.g. the aerosols) to actually make contact with the cells in the host)

If it rely on simply diffusion to bump into the host cells' receptors, what makes the odds high enough so that such proliferation strategy is efficient enough to ensure the virus to multiply and proliferate?

In addition, once it has released its DNA into the cell, what helps the DNA to reach the nucleus and not drifting randomly within the cell for a long time, that is, is there exist mechanisms or transportation pathways that actually guide the DNA from the perimeter of the cell through the cytoplasm in the middle and towards the area where the nucleus lie?


texts:
Seral communities modify the environmental conditions in such a way that these are less favourable for itself and more favourable for the next community. Each community acts to end itself.

If the same is applicable to the climax community, what does it lead to?*


texts: Question about proto-oncogenes and oncogenes?

texts:
My textbook says:

  Growth-promoting genes are called proto-oncogenes. Some can be changed into oncogenes by a point mutation that alters the ability of the proto-oncogene to be switched off. They remain permanently switched on. Oncogenes promote unregulated cell division. Such cell division leads to a tumour.

Does this mean that the change from proto-oncogene to oncogene is not a mutation in the exon, but rather in the intron?

I hope I used these terms correctly. Thank you for any help :)


texts: Is the Common Cold an Immune Overreaction?

texts:
It's my understanding that the majority of symptoms associated with the common cold (runny nose, inflamed sinus, slight fever) are essentially the result of the immune system's response.

I've never heard of someone dying of the common cold (unlike influenza), even in immune compromised people. As such, what damage would the cold virus inflict if there was no immune response? Would it be catastrophic?


texts:
With respect to this paper:

Global Analysis of Host-Pathogen
Interactions that Regulate
Early-Stage HIV-1 Replication

What does the term "host cellular factors" mean??


texts:
In the context of COVID-19, why is it possible to inject someone else’s antibody protein into a person without fear of stimulating an immune response. Does this indicate that, somehow, antibody conformation is universal?
Or rather ...
The immune system must differentiate between cellular and fragmentary material? It will attack any cellular material it deems ‘non-self’. But if foreign non-cellular material enters the body, such as dust, pollen etcetera we are in the realm of an allergic response. The allergic response is not absolute: only certain materials will cause a reaction.
So perhaps foreign protein, such as donor plasma products, are treated as potential allergens which, happily, do not cause an immune response; unlike midge spittle?


texts: Number of alleles' variations in a mushroom that has over 20,000 sexes

texts:
I am trying to understand the mating behavior of a particular species of fungi known as Schizophyllum commune, or the split-gill.

I found a blog post that explains the mechanisms that define the mating types (or sexes) of this species (there are about 28,000 sexes):
http://www.creativewi.re/2017/11/this-fungus-species-has-more-than-23000.html

The post says that the fungus' mating type is defined by a set of two genes that are present on two loci on the chromosomes. Each of these two genes has two alleles. Again, each allele has a number of variations. For example, a fungus with the A1 allele at locus A, and the B2 allele at locus B has the A1B2 mating type. This is a simplified example that doesn't include the alleles' variations.

Now, my question is as follows:
what is the number of these alleles' variations at each locus, and how did the scientists count the total number of sexes?

Thank you!


texts: Will a polyclonal antibody attach to proteins of different kDA?

texts: If I have a GST 26kDa polyclonal antibody, will it bind to the GST 28kDa protein as well?


texts: To what extent is excretory control a learned vs. instinctive behavior?

texts: Human babies are clearly not born knowing whether/how to hold in urine and feces, and teaching them to do so requires a nontrivial (really nontrivial...) amount of work on the parents' part.  But once this skill is learned, it becomes so effortless that one does it automatically in one's sleep.  I can't think of any other learned behaviors that are either (a) performed while unconscious, or (b) controlled by the parasympathetic nervous system, both of which are true for excretory control.  The fact that, once learned, excretory control becomes so "automatic" seems to suggest to me that it's not entirely a learned behavior.  If no one ever actively taught a baby to control its bladder and bowels, would it eventually learn to do so on its own (suggesting that excretory control is actually an instinctive rather than learned behavior)?  Presumably this experiment has never been performed on a human baby, but are non-human animals born knowing how to control their bladder and bowels, or is this a learned behavior?


texts: What is the average eye sight for humans? How bad is one's eyesight if you are1 or 2 SD below average?

texts:
What is the average eye sight for humans? How bad is one's eyesight if you are 1, 2 or 3 SD below average?

I googled but it was hard to find good search terms.


texts: What's the difference between blood value units 'mE/l', 'mU/l', 'mIU/l' and 'mEq/l'?

texts:
Wikipedia suggests 'mE/l' is the dutch or german translation (using 'eenheid'/'einheit' for 'unit') for 'mU/l', which can also be written as 'mIU/l'.

The article mentions The IU should not be confused with the enzyme unit, also known as the International unit of enzyme activity and abbreviated as U.. Is it safe to assume that in case of the unit 'mU/l' one never means the enzyme unit? I figure this is because the enzyme unit specifies a rate of conversion, which is not a blood value and would be meaningless to specify 'per liter'.

I have also encountered 'mEq/l', of which I am pretty sure it is different from 'mU/l', going by the wikipedia article.


texts: Do Asian koel males communicate through calls?

texts:
Male Asian koels are heard making long koo-Ooo s  which are returned by similar koo-Ooo s1 from some far away place. While the female makes short shrills.

I never had the opportunity to see the other bird and find out its sex. But it sounds just like the first one.

Is it actually communicating with a male bird? What is the known reason if so?

1 The reply calls (to be found around 0:29) in the video are really low.

Note:

A singing male bird also gives desperate accelerated calls when  mimicked.
Its breeding season has just begun in India and this communication can be heard.


texts: Where do the four ADPs come from in the second stage of glycolysis?

texts:
In the first stage of glycolysis, the two molecules of ATP are broken down into 2 ADPs + 2 Pi through hydrolysis, then in the second stage of glycolysis they are phosphorilazed to obtain 2 ATPs. How can this process happen twice to yield 4 molecules of ATP if we only have 2 ADPs to begin with?

Note: I'm not asking why the process happens twice, since it's easy to see that the Fructose-1,6-biphosphate is being broken down into two Glyceraldehyde phosphate molecules. I'm asking how can the process of producing two ATPs happen twice if we only broke down two ATP molecules into ADP.


texts:
I am new to biology. I searched a lot to find an article that explains what "pan-specific" antibody is but I could not find anything substantial that would help me understand what it is.

An example from an article

  In this report, we address this long-standing analytical deficiency by
  developing a pan-specific antibody against the pHis modification. We
  show that this antibody can be used to detect protein histidine
  phosphorylation in vitro and in vivo.

Another definition

I appreciate if someone helps me with finding a scientific explanation (article/ book) on what "pan-specific" antibodies are.

Kind Regards,


texts: How does most of lymph get back into the blood stream? (I don't mean the lymphatic system)

texts: I once read that it was because of osmotic pressure that it returns to the blood stream, by entering the venules. But why? If lymph originated as plasma how come that the solute concentration is higher in the venule? Doesn't plasma contain solutes such as salts, nutrients, oxygen, etc. ?


texts: Is there a significant difference in sedentary calorie-burn between a thinker and non-thinker?

texts:
I've read that, on average, a sedentary female burns between 1,600 - 2,000 calories and a sedentary male burns between 2,000 and 2,500 calories. I've also read that the brain itself burns quite a few of these.

Let's say two people are exactly the same, and have the exact same (sedentary) lifestyle—except one of them often does intense mathematics. Is there a significant difference in calorie burn?

If so, how much is it?


texts: from an ageing reproductive stem cell's DNA to baby's "brand new" somatic cells' DNA

texts:
On the one hand, somatic cells's DNA age as life goes on, mitosis after mitosis, and that is reflected into reduced telomeres.

On the other hand, during life, reproductive stem cells must age too. However one half of the DNA of some random old reproductive stem cell is eventually transferred through reproduction, and the ageing cycle begins again, with new somatic cells with long telomeres.

What mechanisms can explain reproductive stem cells DNA do not age as somatic cells' DNA ? Or do we know how telomeres are growing back from old reproductive stem cells to gamete during meiosis ? Put another way, how is it possible that we are born with long telomeres ?

I am sorry for the formulation of my question. I think it is understandable but not really well written. However I don't know how to formulate it another way yet. Do not hesitate to reformulate it if you feel like it.

Thanks.


texts: What are the safety precautions I should take if I want to experiment with C. elegans (at home)?

texts:
Caenorhabditis elegans (C. elegans) is a nematode (roundworm), and many nematodes do infect humans and cause diseases.

How much is C. elegans safe (or unsafe) in this respect?

C.elegans is a popular model organism, but is it safe to experiment with it at home? Or risk of infection shall outweigh desire and interest for home science?


texts: why has evolution favored sexual reproduction using two mates over sexual reproduction using three mates?

texts:
Many animals species require two members — a male and a female — to sexually reproduce. Why has nature (or the process of evolution) chosen to favor the form of sexual reproduction which requires two members? Why didn't nature encourage the form of sexual reproduction which involved three members?

The reason for sexual reproduction being a better choice over asexual reproduction is justified by saying that sexual reproduction involves mixing of genetic information from two living beings and hence if one set of them had an error, the other would compensate for it. With the same kind of reasoning, we can argue that sexual reproduction involving more than two organisms coming together would cause better genetic variation, shuffling of mutations, etc. and thereby produce a better offspring.

However, most of the organisms as we see today have evolved to reproduce sexually using two beings of the same species.

Consider an animal species which has 24 pairs of chromosomes.

Sexual Reproduction Type 1:

There are two sexes: male and female. During the event of sexual reproduction, the male transfers 24 chromosomes to the female where the chromosomes from both the sexes are mixed to produce an offspring.

Sexual Reproduction Type 2:

There are three sexes: male, female and [insert word]. During the event of sexual reproduction, each member transfers 16 chromosomes to the female where it gets mixed to produce an offspring.

We don't observe sexual reproduction of type 2 (or it is rare). Doesn't the type-2 form of sexual reproduction cause better mixing of genetic information than type-1 form of sexual reproduction? Despite the aforementioned advantage, nature has chosen to encourage the type-1 form of sexual reproduction. Why is the type-1 form of sexual reproduction more common than the type-2 form of sexual reproduction?

This question can be extended to "Why has evolution favored sexual reproduction involving two mates than sexual reproduction involving $n \space (n > 2)$ mates?


texts: Fast standing and the heart's insufficient accommodation of the increased venous return

texts:
Assume you are 45 minutes on the supine position. Furthermore: you stand all of a sudden and fast and without sympaticus activity.
The venous return (smooth musculature of vessels) accommodates faster to the change (decrease of venous return) so returns blood to the heart before the sympaticus has accommodated for increased cardiac output.
This creates a significant increase in the blood volume entering the heart.
In pathological situation where systemic vasoconstriction not occurring normally, the heart is not capable of handling the overdistension; resulting in a pain during the second cardiac cycle.

I am interested in knowing which phase the heart is most vulnerable:

filling,
isovolumetric contraction
ejection
isovelumetric relaxation

or more explicitly (from my answer here)

Atrial systole
Isovolumetric ventricular contraction
Rapid ventricular ejection
Reduced ventricular ejection
Isovolumetric ventricular relaxation
Rapid ventricular filling

I think filling can happen normally, but not with the sudden isovolumetric contraction (most sympathetic innervations here, so therefore I think this is the weak link).
When there is too much blood in the ventricles, some of the blood is reflected back from the ventricles into the atria causing a painful sensation and possibly tachycardia (as well as an possible increased risk of atrial fibrillation if such events happen regularly).

Is the isovolumetric contraction (systole of ventricles) of the cardiac cycle the possible weak link in accommodating a sudden increased venous return?


texts: Why is the nutritive value of grass to humans compared to alternatives?

texts:
Cows thrive on eating large amounts of grass. That's because they have specialized digestive processes, such as chewing a cud that maximizes the value of grass to her. Humans who don't have these processes, don't get as much a of a benefit.
Suppose a human being were "stuck" for food, and the most available food was grass. What percentage of the nutritive value of the grass would the human obtain, compared to what the cow would obtain? Also, how would the nutritional value of grass (for humans) compare to vegetables such as lettuce or spinach? And is the lack of nutritional value of grass one reason why humans prefer to eat beef rather than grass, even though 90% or so of energy is lost at every level of the food chain?


texts:
I read that chromosome inversion is a type of genetic mutation.

  Why does inversion happen? What is the purpose?

I also read that if genes do not match up during cross over between inverted chromosome and non-inverted chromosome could cause birth defect.

  Then would that make chromosome inversion fall under harmful mutation?

In addition, there are two types of inversions: paracentric and pericentric. The difference between these two inversions is that one of them invovles centromere and the other one does not.

  What is so important about centromere?

And lastly,

  Does inversion happen before humans are born, or after they are born? When does it happen?

I apologize if my questions are vague. I do not have much background information on chromosomes.


texts: Does sodium lower the harmful effect of potassium on kidneys?

texts:
As far as I have read so far, it seems that potassium and sodium are trying to expel each other from the human body. A lot of documents on the web say too much sodium pressures the kidneys could cause a kidney failure. The same is also said for potassium.

If a person eats a lot of potassium-rich foods, does increasing sodium intake cancel out the harmful effect of potassium on the kidneys, or just double the harmful effect (he/she gets the harmful effect from both potassium AND sodium)?


texts: Are there any forms of heart failure where cell size decreases?

texts:
I think hypertrophy happens in most of the cases. However, I am not sure if hypertrophy always happens. I started to think about wet lungs (pulmonary reason for the left-sided heart failure).

Can the decrease of cell size occur in the heart failure?


texts:
I saw this foto on Reddit recently:

Is this possible? How can a grasshopper become like this? Is this just natural genetic mutation?


texts: What is the difference between "genetic" and "hereditary"?

texts: What is the difference between the adjectives "genetic" and "hereditary"?


texts: How to manage fat-gluten oxidation in celiac disease?

texts:
Assume you have been in non-gluten diet 20 years.
You built mass 8 mass with substances containing gluten (endogenous gluten stored in fat).
Then, celiac disease is diagnosed.
You have been 3 months in gluten free diet.
After mass period, you go to fat burning period.
The challenge starts: endogenous gluten stored in fat.
It is painful if too intensive training program.
Even little amount of gluten causes enteropathy.

What are the protectant methods for burning fat containing gluten?

How can you prove that there are no gluten-derived peptides that accumulate somewhere?
Since the cellular receptors for gluten have been identified, I think this may be over-complicating things. - Ryan's answer

I have not found any good solution for this, since I do not understand the pathophysiology enough well.

Toxic factors related to celiac disease

gliadin
...

How is endogenous gluten released from fat?


texts:
I left a cup of tea with Lemmon on my desk and after a while green mold start growing on the water. From my understating this is Penicillium digitatum. I gave it some sugar and after one day black spots appeared. I read that it can be little bit dangerous to inhale mold so I wrapped the cup with saran wrap and make some holes in it in order to give the mold oxygen.

What do I need to do in order to give the mold better condition to grow?
Can it be dangerous growing it?


texts:
I have a project about extracting features from a homemade ECG. I need the PQRST points from the signal of the heart beat. The ECG I'm using has 3 electrodes that attach to the chest.

The problem is I don't know where I should define the PQRST points because the result does not look much like an ECG. I want to try to create a program later that can find those points.

Here are the raw ECG traces data taken from 3 subjects that were alcohol-intoxicated (0.2 to 0.3 promille):

I'm guessing the red and orange points here. And I'm pretty sure the green points are accurate located:

Green points is easy to locate but the orange is a little harder and the red ones are really hard to pin point out. Those points can be used to define the length of different complexes, intervals and segments of PQRST.

Which points is safe to extract? Where exactly are those points located in the graph?

Is the data too inaccurate for finding abnormalities?

Is there any other useful feature, beside heart rate, I can extract from my graph?


texts: Using the IMGT/GENE-DB service to find RSS

texts:
I'm trying to get the data for the Human and Mouse 12 and 23 Recomination
Signal Sequences (RSS), to run a classification algorithm on it. I'm not a
biologist, so I apologise in advance for my misunderstandings and
confusion.

A version of the data is available here, but I thought I would try to
get it from www.imgt.org, if possible. There is also another slightly
different version available for the mouse here.

I'm trying to follow the instructions at IMGT-FAQ to obtain Recombination Signal
Sequences for the mouse.

Here is what I have selected at the search page:

Identification:
Species : Mus Musculus
GeneType: any
Functionality: functional
MolecularComponent: any
Clone name: <blank>

IMGT group: IGHV
IMGT subgroup: any
IMGT gene: <blank>

I'm not clear what "Locus", "Main locus", and
"IGMT group" mean here exactly. Specifically, what is the difference
between "Locus" and "Main locus"?

I think, but am not sure, that IGHV corresponds to V genes in the
Immunoglobulin heavy locus (IGH@) on chromosome 14, where locus here
denotes collections of genes. Clarifications and corrections appreciated.

I would have expected that the IGH locus would correspond to "IMGT group"
entries like "IGHJ, IGHV" etc, and the IGK locus would correspond to IMGT
group entries like "IGK, IGKJ, IGKV", but no matter what I select for
Locus, it does not change the possible entries for "IMGT group".

Running the search gives

Number of resulting genes : 218
Number of resulting alleles : 350

As instructed, I went to the bottom, selected "Select all genes", clicked
on "Choose label(s) for extraction", and selected "V-RS".

I got

  Number of results=98

The first few results were

>X02459|IGHV1-4*02|Mus musculus_BALB/c|F|V-RS|395..432|38 nt|NR| | | |
|38+0=38| | |
cacagtggtgcaaccacatcccgactgtgtcagaaacc

>X02064|IGHV1-54*02|Mus musculus|F|V-RS|295..332|38 nt|NR| | | | |38+0=38|
| |
cacagtgttgcaaccacatcctgagtgtgtcagaaatc

>M34978|IGHV1-58*02|Mus musculus_A/J|P|V-RS|554..560|7 nt|NR| | | |
|7+0=7|partial in 3'| |
cacagtg

Ok, now I'm confused. The lengths of the RSS should be 28 or 39. but I
counted lengths of 4,7, 31, 38, and 39. Are the results here not supposed
to contain the 12 and 23 RSS?

So, I must be misunderstanding things here. Possibly many things. Any
explanations and clarifications are appreciated.


texts: Do plants have distinctive DNA genomes from each other like humans do?

texts:
Can exact same species of plant have a distinct genome from others of same exact species growing nearby or in a different place/country etc. ?

Can a leaf be traced to the the exact plant based on DNA if we were to be given DNA of the "parent" plant of the leaf, and two test plants' DNA of exactly the same species?


texts: Can mutation rate be increased for instance by mutagenesis targeting the DNA polymerase?

texts:
I am studying a non-cultivable bacterium living in an insect host, and I would like to generate some random mutants of this bacteria while preserving the insect.

I am wondering if one way to do so might be to use directed mutagenesis directed towards the bacterial polymerase, which would leads it to increase the error rate.

Does any one has already seen a study with this kind of approach?
Does any one knows or guess another way to obtain some random mutants of the bacteria while preserving the host insect?


texts: Question regarding the number of alleles

texts:
Why is it that in biology we often say that a gene has two alleles? When we analyze allele frequencies (e.g. using Hardy-Weinberg Equilibrium), formulas are often generalized for two alleles of a gene.

Given mutations, isn't it quite likely that a population will have more than two alleles for a gene?


texts: Why do fully grown organisms need protein intake?

texts:
If proteins are building blocks of an organism then it makes sense why a growing organism would need an intake of them, but why would a fully grown organism need proteins (aside from those lost by shedding skin, growing hair etc.) and not recycle other proteins back into amino acids.

I understand that protein can be broken down to generate energy when needed or when there's too much of it in the body, but given enough energy from other sources (like glucose), it seems that proteins wouldn't need to be used for these processes.
Is there perhaps a net loss of amino acids during protein biosynthesis?

My question was inspired after reading this study of a man who was fasting for 382 days and was given only water and mineral supplements:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2495396/pdf/postmedj00315-0056.pdf


texts: Why is epinephrine not part of the somatic nervous system?

texts:
I learned that the adrenal medulla releases epinephrine, which is a vasodilator of the vessels that lead to the skeletal muscle.

I also learned that somatic nervous system only uses Achetycholine as its hormone (not epinephrine).

I also learned that the somatic nervous system controls skeletal muscle.

So, why is epinephrine not considered a part of the somatic nervous system hormones, if it is controlling the skeletal muscle? What is wrong here?


texts:
TCGA provide CNV data for each cases like this.

I want to know, how can I calculate CNVs from this data? What are standard  algorithms and methods used?


texts:
I have a part of a parasitic worm frozen at -20°C. Do you think that DNA extraction using DNeasy kit without any pre-treatment is sufficient for DNA extraction?
Or would you recommend bead beating / nitrogen?
I do not need high quality DNA. It is just for the identification via shotgun metagenomics (shotgun metagenomics because 1) the parasite identification failed so far via PCR/immunostaining and 2) there is some human traces as well).
I refer to " DNeasy Blood & Tissue". It comes with protocols for eucaryotic tissue. The sample is extracted from ejaculate. I also do not need a whole lot of DNA, about 100ng should be enough.


texts:
This tiny guy stumbled into our house in the suburbs of Sydney. What species is it?

It's dark and has two yellow stripes going along the length of its body. They start on its head and go right above its eyes.


texts: What happens when you mix type A with type B blood (and v.v)

texts:
What happens when you mix different blood types that are not compatible?

For example, if a patient has type A blood and receives type B blood, or v.v.?


texts: Sensory adaptation regarding smell and hearing

texts:
Imagine the scenario. My friend and I are playing a game of chess near a highway. Initially, I notice the sound of the highway. While I'm playing chess, however, I do not notice it. After the game my friend asks me if I can hear the highway, and I regain my ability to notice it. This seems to be different for smells.
If we were playing chess in a room filled with garbage, the smell would gradually fade away. If my friend asked me if I could smell the garbage, I would not be able to smell the garbage as severely. What is the cause of this difference?
It seems that visual and touch follows the same pattern as hearing. What makes smell unique?


texts: Chaos theory and population cycles of odd periodicity

texts:
I have just begun to read about Chaos theory and have come across the statement that "Period three implies chaos."

My question: Does any odd period imply chaos or only 3? If so, how can populations of cicadas that cycle every 17 years exist?


texts:
I live in northern Illinois and had these guys appearing in my room. No facial markings and they seem non agressive.

About 2cm in length with off white u shaped markings below it's waist and a single white line a few segments down.


texts:
Can anyone identify this bird: it looks like a zebra finch but they are not native to UK  are they?

Photo taken from my garden in Shoreham, West Sussex on 16/8/2014.


texts: What is the magnification necessary to see pond life

texts:
My daughter is 5 and wants to learn about Biology. I thought a great start is to see life from pond water through a USB microscope. It would be great if she could see organisms like amoebas, flagellates and ciliates with her own eyes. The microscopes I have seen typically have a zoom range of about 40 to 400x.

Would this range be sufficient to see microscopic pond life?


texts: If I were to harvest an agave plant for its nectar, would it kill the plant? I have watched videos of the process and it seems quite invasive.


texts: identifying which SNPs sit in TFBS (Yeast)

texts:
i have a set of ~11k SNPs for Saccharomyces cerevisiae, baker's yeast and i would like to identify which ones of these sit in transcription factor binding sites and if they do information on the relevant TFBS.

i've scoured this site and the internet and i couldn't find a downloadable database that would give me locations of all known/verified TFBS for yeast. i've studied the YEASTRACT website thoroughly but didn't find such database to download information about TFBS for all the ORFs/genes in one go.

moreover, when i tried getting the information manually through YEASTRACT search on-line i found results confusing. for example: searching for TF for ORF "YOL166W-A" returns a list of 4 TFs. clicking on one of them, say Sok2p, takes you to another page which says, amongst other things, that the corresponding TFBS is "acMTGCAKg"... what does it mean? (i know the ACTG alphabet but what are the 'a', 'c', 'K' and 'g' symbols?) and what does this tell me about the actual location of the binding site? do i have to BLAST the whole genome to identify it? (shouldn't there be a database with this info for yeast already?) if so, how do i BLAST for symbols like 'K' and 'g'?

i have background in stats but currently work in genetics applications, hence extracting relevant bioinformatics data is very confusing for me on occasions. any help will be appreciated.


texts:
So I am thinking about a career in synthetic biology, but I am not sure what route should/needs to be taken. I don't want to do technician work--I want to be involved in the planning. Y'know, the exciting stuff. :)

I'm wondering whether I should go for a Master's or a PhD (or is a Bachelor's enough?)

It's a young field, so I'm having trouble finding this kind of information online. Any help would be much appreciated!


texts: Effects on body without fitting routine to external time (non 24 hour Circadian clock)

texts:
Often I find myself trying to fit my daily routines to factors such as those of the external time, e.g. to light levels outside, and those that others around me live by.

However this often seems inconvenient- often having to round up or round down time spent on certain activities to fit them into my day. Sometimes I find myself tired which affects the quality of my work, but I 'know' it is not necessarily time to sleep due to the outside light levels and the timezone given to me, so I must carry on until some 'reasonable' time is reached.

I was wondering, is there a significant (negative) effect to the following process:

Assuming I need to do nothing which involves direct involvement of others, I attempt a task (inside, controlled temperature with lighting if needed) which I want to attempt until either it is complete, where I then move to the next task, or feel like I must postpone to perform a bodily function (eat, sleep etc.) until these themselves have been satisfied.
Repeat this indefinitely, irrelevant of outside time conditions/ factors, which we assume to be reasonably 'normal'.
(I have an infinite supply of food, water etc. )
Assume work can only be completed with at most minimal tiredness.

I would expect that maybe on average, the times at which humans are to proceed through the tasks match up with the 'normal timings', but I would argue that for myself, this would be caused by quite large fluctuations either side that cancel each other out. (Perhaps at some point I would wake up in the afternoon, another day go to sleep in afternoon).

I would like to know how much of our regular routines is psychologically influenced by others around us compared to how much this is intrinsically in our genetics.

These 'normal' routines seem to make sense for many primates- time of day effects ability to see surroundings, perhaps what food sources are present. But one could argue whether this is as relevant for humans with technology to overcome many of these factors.

I am aware of the Circadian clock, and that it has its own genes, and that it is maintained through certain light stimuli, but I do not know what precise functions it maintains in the body.

So

What would be the physiological/psychological consequences of ignoring the factors of time when completing tasks?

How much of the common human routine is psychological (from being influenced/ made to by others) compared to intrinsic instinct?

Are there any sources/studies conducted on this before?


texts: I've read that some people in some countries actually use tapeworms as a form of losing weight.  What are the dangers to these people?


texts: How is the urea cycle regulated with respect to protein deficit?

texts:
Proteins cannot be stored in the body. Excess proteins from the diet are deaminated in the urea cycle that takes place in the liver. The liver is the first contact since these amino acids are delivered through the portal circulation.

What I do not understand is what controls the extent of amino acid breakdown in the liver. For example, suppose there is a man who hasn't had protein in a month, and has a net protein deficit, what determines that there shouldn’t be much deamination in the liver?

For carbohydrates and sugars, insulin and glucagon balance regulate the main enzymes controlling the steps in glucose phosphorylation hence maintaining homeostasis. Since this is at an organismal level and not the cellular level, like glucose, I would expect the control of urea cycle also to be hormonal. Since there is no hormone that reflects protein status (at least to my knowledge), what determines the activity of the urea cycle?


texts: I've heard that narwals can grow their tusks up to 16 ft long. What do they need the tusk for? Hunting?  Comunication?


texts: Is there a balance or feedback between O₂ and CO₂ in the atmosphere?

texts:
Is there, globally, a balance of the concentrations of oxygen and carbon dioxide  in the atmosphere?

Plants convert CO₂ to O₂,
and with the concentration of O₂, the tendency of plants to oxidize to CO₂ increases. That is, plants burn better with more oxygen.

Based on this there may be a feedback of increasing CO₂ concentration to increasing O₂ concentration back to increasing CO₂.

This feedback requires that plant growth increases with increasing CO₂ concentration.

Otherwise there would be only a limit to the oxygen concentration as at some concentration of O₂, even a wet rainforest burns explosively.

Does a feedback loop like that exist?


texts: To a population with no immunity, why is smallpox or measles more deadly compared to COVID-19?

texts:
Specifically, this is not a question asking how easily a virus spread in a
population (airborne, asymptomatic spread, etc), but regarding the
mechanism or the "havoc" it wreaks once inside a person's body.
Edit: The question is based on the assumption that, once a human body can readily recognize the virus signature and starts flooding the blood with anti bodies, the virus won't be a problem.

Today, We have no prior immunity to COVID; 400 years ago, Americans
had no prior immunity to smallpox either.
Both virus can be effectively combatted once the body has immunity
(recognization and anitbody production).
Yet, smallpox is so much more lethal and its damage horrifying.


texts:
I understand that there would have to be a portion of liver present to regrow from, so how much liver would the minimum to be able to regrow?

By what mechanism does regrowth occur?


texts: Do cells in healing ligaments or tendons have deformation processes? If so, what are they?

texts:
I am trying to better understand how non-muscle tissue in the muscuoloskeletal system heals. Specifically, I am interested in how ligaments or tendons heal once torn.

I read the following text:

  If the muscle pulls the damaged tendon and then releases it then we have a deformation cycle that the cells are able to detect. They also then receive the information they require regarding orientation. This is why the elasticity of the early callus is important; the tissue must be able to be pulled out and then return to its original shape in order to receive information about orientation.

Source:
http://www.peraspenberg.com/texts/how-do-tendons-and-ligaments-heal/

I don't understand what they mean by "deformation cycle" and how cells detect it.

Is there a name for this cycle? If so, how do the cells detect tissue deformation?

Also, if there is any literature that specializes in the tissue of ligaments or tendons, recommendations would be appreciated. I have plenty on muscle tissue and some on bones, but not ligament or tendon tissue regeneration.


texts:
I live in Italy (Emilia Romagna), and my house, seasonally in spring, is full of these guys, someone knows their name and if they could represent a problem?
They are very tiny slightly less than 0,5 cm including the antennae.


texts: How octopus develops its imitation skill?

texts:
I've watched one documentary about a Mimic octopus which they can imitate another animals in several form e.g. a Lion fish, a Sea snake, a Flatfish, etc. My question is how these octopuses can have these such skills? Imagine that they can not see themselves via a mirror but their imitation is so perfect.

What is a theory behind this?


texts:
The common explanation as to what the primary mechanism of action for organophosphates (and carbamates) is is the inhibition of the enzyme acetylcholinesterase and resulting buildup of acetylcholine at neuromuscular junctions, which ultimately results in respiratory failure. However, there is evidence that this may not be the case.

Firstly, a study reported that the nerve agent VX has been found to attack at least 132 different proteins, some of which were associated with metabolism.
Source: https://www.ncbi.nlm.nih.gov/pubmed/28267914

Also, another study showed that, even when the enzyme was protected against the action of organophosphates, nerve agents still exhibited toxicity.
Source: (http://www.rand.org/publications/MR/MR1018.5/MR1018.5.chap5.html) (Found in the Chapter 5 PDF, under "Non-AchE Effects")

Also also, another study was conducted on the matter. The test subjects were mice genetically engineered to lack acetylcholinesterase. The study found that the mice that totally lacked the enzyme not only lived (For over 34 days, no less), but were also twice as susceptible to OP poisoning as mice with the enzyme and exhibited the same symptoms.
Source:https://www.ncbi.nlm.nih.gov/pubmed/11602663

So, how do organophoshates actually act to cause the symptoms associated with OP poisoning? What proteins do they affect? There seems to be a great abundance of evidence that the effects of poisoning are not due to AchE inhibition.


texts: Resolution of MRI can be improved if FOV is reduced keeping other factors constant, but this reduces voxel volume, which in turn reduces SNR. How much SNR is enough for good imaging?


texts: How do biological communities at deep-ocean hydrothermal vents migrate between vents?

texts:
Much interest in the astrobiology community has been generated by the discovery of biological communities populating deep-ocean hydrothermal vents (i.e. "black smokers"). (1) These ecosystems rely on chemoautotrophic bacteria/archaea extremophiles as primary producers living at 40-80 C temperatures.

However, the lifetimes of these black smokers have been estimated to be of order 25 years. How  are these biological communities able to migrate to newer, active vent systems in conditions of extreme cold and high pressure?

(1) Lonsdale, P., 1977, Deep Sea Research, 24, 9


texts: It was found a few days ago in the state of Virginia, on the east coast of the United States.


texts: Do trees have genes for stopping growth?

texts:
Do trees have genetically encoded to stop growing at some height, to keep dividing the cells only to a certain amount, or to pump nutritions only till it's advantageous because they've already overgrown their companions? Or do they just keep growing till they can?

I was inspired by this article, according to which the height limit is about 130 m. Since if the second one was true, it would be possible to grow a 130 m tall tree with enough nutritions.

Also, the evolution of trees wouldn't mean to getting more genes of height, but to use nutrients more efficiently.


texts: Why does NAD+ become reduced if it gains a hydrogen proton?

texts:
I've heard that $\ce{NAD^+}$ gains a Hydrogen proton during glycolysis and the Krebs cycle and becomes reduced to $\ce{NADH}$. However, isn't reduction when a molecule receives an electron?

Maybe I've been misinformed? Does $\ce{NADH}$ gain a Hydrogen electron, not a proton?


texts: Which reflex arcs work in Heart with extrasystoles?

texts:
I am researching what is triggering the extrasystoles - initial idea from this thread about Which ionic channels of Pacemakers can work in very low frequencies in extrasystole?
I am interested in the reflex arc with extrasystoles.

I am not completely sure if the intrinsic regulation of the heart can start specific stimuli.
I have now intuition that not possible.

What are the reflex arcs of the heart?


texts: Can a strand not be synthesised in 5' -> 3' direction?

texts:
I've been solving some biology questions, and according to one of them ( I have the responses too) the following phrase is false:
"Both strands are always synthesised in the 5' to 3' direction."
How can this be? From what I know DNA is always read from 3' to 5', and synthesised from 5' to 3'.
When is DNA not synthesized from 5' to 3'?


texts: How do female hormones cause blood to clot?

texts:
On most female-hormone supplements you get a warning that is something like this:

  The use of a combination hormonal contraceptives (CHC), like NuvaRing, is associated with increased risks of several serious side effects, including blood clots, stroke, or heart attack. (Nuvaring)

The use of a CHC, like NuvaRing, is associated with increased risks of several serious side effects, including blood clots, stroke, or heart attack.

It also goes onto state that smoking can increase these risks.

What makes these hormones so dangerous (prone to clotting)?
If a person is naturally high in these hormones are they at a higher risk of blood clots?
Why/How does smoking affect the hormones - or is the increase risk just due to the natural risk of smoking?


texts:
Is there a terminology for the average timespan between generations, like ΔG ?
I mean by that the time from the parental generation being mature to the filial generation being mature.


texts:
It was soft and covered in flies. My guess is fungi.

Location: South Florida.


texts: How does coconut water solidify into hardened coconut meat?

texts: At first, the coconut is filled with liquid endosperm. Later when it ripens, the outer layers form brown fibrous covering, and the inner solid layer turns brown and hardens. Within that, a white layer forms (which is soft and thin at first and then gradually hardens and thickens). After ripening, there is a white layer with very little fluid. So, it's gotta be the liquid endosperm which has hardened over the course of time to form the white layer. So, how does it harden?


texts: Will omega 7 make it harder to produce high quality meat?

texts: I heard from a medical show that Omega 7 makes it harder to gain weight, and was wondering if I would be be able to put on muscle better if I have sheep and pigs getting omega 7 through sea berry branches.


texts: Why did we lose our fourth type of cone cell (in the eye)?

texts:
Most species of birds, reptiles and fish have four types of cone cells in their retina, thus they have four independent channels for conveying color information. They are:

short-wave (S) cones: sensitive to colors with short wavelengths.
middle-wave (M) cones: sensitive to colors with medium wavelengths.
long-wave (L) cones: sensitive to colors with long wavelengths.
ultraviolet (UV) cones.

This condition is called tetrachromacy. Wikipedia mentions:

It was the normal condition of most mammals in the past; a genetic change made the majority of species of this class eventually lose two of their four cones.

We have only three. My question is, why did we lose our UV cones? I searched a little about this and here's what I found:
Scientists Have Found a Woman Whose Eyes Have a Whole New Type of Colour Receptor

According to estimates, that means she can see an incredible 99 million more colours than the rest of us, and the scientists think she's just one of a number of people with super-vision, which they call "tetrachromats", living amongst us.
They took 25 women who had a fourth type of cone cell, and put them in a dark room. Looking into a light device, three coloured circles of light flashed before these women's eyes.
To a trichromat, they all looked the same, but Jordan hypothesised that a true tetrachromat would be able to tell them apart thanks to the extra subtlety afforded to her by her fourth cone.

Which means some of us still have it. What I don't understand, though, is why this isn't a more common trait? Evolutionarily, is being able to perceive vision using three cones "enough" for humans?


texts: Identity By Descent vs Identity By State

texts:
Background

The concepts of Identity By Descent (IBD) vs Identity By State (IBS) are central in population genetics, yet I fail to fully wrap my head around the definitions.

You can find examples where my understanding of IBD vs IBS is quite poor in @DermotHarnett's answer here or in the comments with @PaulStaab here. @PaulStaab suggests that different authors have used different definitions of IBD and IBS.

What is unclear to me

From what I remember from Hartl and Clark (I don't have the book with me to quote), IBD depends on an arbitrary time threshold in the past beyond which if coalescent events occurred, then we still call the two alleles IBS (Identical by state) and not IBD. The idea that the concept of IBD depends on an arbitrary threshold bothers me though!

I suppose that two alleles can be IBD without being IBS in the case where a mutation or recombination event in the middle of the sequence of interest prior (looking backward in time; more recent) to their coalescence. I suppose two alleles can be IBS can not be IBD only if we use an arbitrary threshold that is older than their coalescent time or if convergent/parallel evolution happened.

Questions

Does IBD depends on an arbitrary threshold?
Are there several definitions of IBD and IBS in use?
Does IBD implies IBS?
Does IBS implies IBD?
Can you please make a short review of these definitions to clear things up?


texts: How does evolution explain the apparation of different group like: mammals, insects etc

texts:
When I am learning about evolution I barely see any source that explains how insects, mammals, reptiles and fish came to be. Can someone show me a source where I can learn about this? Especially insects and mammals - I want to know how those 2 distinct group came to be.

And I have a related question: can a fly evolve into a rabbit given enough time with the necessary condition? (I know the question sound stupid but please can someone explain me that)

I have a layman understanding of evolution. So please can any of your source or explanation be simple? Thank you.


texts: Are there gaps in what our ears can hear?

texts:
I know about the hair cells in our Cochlea and it is the movement of the fluid that makes them vibrate. And it is this that activates the transmission of electrical signals to the brain that become sound.

But I've heard that hair cells are each built to detect specific pitches of sound. And if they don't get that particular pitch then they don't transmit.
So as I understand it, we have cells that each respond to one particular pitch and nothing else. Since we have many that each respond to a different pitch, this is what gives us a wide spectrum of hearing.

What I've been wondering is this, if each hair cell responds to one particular pitch, what happens if we try to hear a sound that is in between two hair cells?

Imagine a hair cell that only responds to 1 Hz (and based on my understanding they do) And next to it a cell that responds to a sound at 2 Hz.
What happens if there is a sound that is 1.5 Hz? Can we not hear that sound because it exists in the gap between our hair cells? Or can hair cells cover a wide range so they overlap and cover the gap?

As our ability to hear sound quantised or continuous?

I know that there are sounds so low or high they are beyond our range of hearing but what about within our range of hearing? If someone played a sound that was right in between two hair cells could we not hear it? Is there a finite number of different sounds that we can hear within our hearing range?


texts: What Proteins Are Universal To All Life Forms?

texts:
According to National Geographic, there are 23 proteins that are common to all life forms:

  All species in all three domains share 23 universal proteins, though the proteins' DNA sequences—instructions written in the As, Cs, Gs, and Ts of DNA bases—differ slightly among the three domains

According to NCBI there are 324 proteins common to all life forms.

How many proteins are common to all life forms, and what are their names?


texts: What pH ranges are used in industrial scale fermentation?

texts:
When reading

  Hans-Peter Meyer, Wolfgang Minas, and Diego Schmidhalter (2017) Industrial-Scale Fermentation. Industrial Biotechnology: Products and Processes, First Edition. Edited by Christoph Wittmann and James C. Liao.
  © 2017 Wiley-VCH Verlag GmbH & Co. KGaA. Published 2017 by Wiley-VCH Verlag GmbH & Co. KGaA.

I came across the following passage describing industrial up-scaling of fermentation processes (in general):

  1.3.1

  Process Development – Scale-Up Starts at Laboratory Scale

  Process scale-up should be considered early on while the biological expression
  system is still under development. Factors such as genetic stability for at least
  the number of generations needed for a scaled-up production, and the need and
  impact on the environment of selection markers, should be evaluated before
  process development is started. The use of antibiotics as selective markers in the
  production medium should be avoided. Throughout development of media and
  cultivation conditions, it is important that parameter settings remain realistic and
  scalable, always indicated with upper and lower limits reflecting the safe operating
  range (process design space), for example, pH 7 ± 0.3.

I am quite surprised about the narrow pH range specified (pH $7 \pm 0.3$). I assumed that the pH range would be much wider, similar to lab scale. Is this really common practice?


texts: Antibacterial hand soaps (and related products); what are they good for?

texts:
From Wikipedia:

  Household use of antibacterials in soaps and other products, although not clearly contributing to resistance, is also discouraged (as not being effective at infection control).

Following the links led me to this paper:  Larson EL, Lin SX, Gomez-Pichardo C, Della-Latta P.,  Effect of antibacterial home cleaning and handwashing products on infectious disease symptoms: a randomized, double-blind trial.  Ann Intern Med. 2004 Mar 2;140(5):321-9.

They conclude:

  The tested antibacterial products did not reduce the risk for symptoms of viral infectious diseases in households that included essentially healthy persons. This does not preclude the potential contribution of these products to reducing symptoms of bacterial diseases in the home.

Upon reading this, my thoughts were:  Why would one test whether antibacterial products have an effect on viral infections diseases?  Since the authors used a control group (those whose soaps didn't have an antibacterial agent), they are only testing for the effect of the antibiotic.

This leads me to the main question:

  Question:  Which common diseases would likely be more affected by antibacterial hand soaps (and other antibacterial products) than their non-antibacterial counterpart?


texts:
If we see at the connectome of c.elegans, it is easy to find "loops", in the simplest case, a neuron that synapses to another and this one backward to the first.

By example, neuron RIAR has 13 synapses to SMDVL (pre-synaptic is RIAR, post-synaptic is SMDVL) and this one has 8 synapses backward to RIAR (pre is SMDVL, post is RIAR).

Which is the scientific term to denote theses structures? Moreover, main hypothesis about its purpose?


texts: I read an article which says that identical twins have 100% similarity between their DNA, but they have different fingerprints. Does that mean the DNA is different in the fingers? What body features can be used to exactly identify the identical twins?


texts: What is meant by Remote Diuretics & Remote Vomiting?

texts:
I have encountered the terms Remote Diuretics & Remote Vomiting separately or sometimes in association in various articles related to medicine.

But I am unable to find any reference to what they actually mean.

Can you help me understand these terms please?

Update

Examples:

  Urine sodium less than 10 mmol/L indicates extrarenal loss of urine
  (remote diuretic use and remote vomiting).

link: https://www.ncbi.nlm.nih.gov/books/NBK470386/

Go to google and search for "remote diuretic" to get more references, some are:


texts: Why are the positions of simple sequence repeats at the gene and related transcript sequences different?

texts: I'm working on the simple sequence repeat (SSR). I found just one region (about 21 bp) with an SSR motif in a given gene. This gene has multiple transcripts, with the same SSR motif located in various positions of different transcripts. Could you please help me understand how this happened?


texts: Is there some research paper which focus on the influence of using cancer cell as experimental materials on experimental result?

texts:
Cancer cell is unstable cell and high variation, but there are many experiment use cancer cell as experimental materials. I always wonder how much influence can using cancer cell as experimental materials exert over experimental result?

Is there any study about this? If any, please give me the study paper.

Thanks for any help.


texts: Does cocaine bind competitively or non competitively to DAT?

texts: I was just wondering whether cocaine, once reaching a synapse, binds to a DAT (Dopamine transporter) competitively or non competitively, or neither of them?


texts: What are chromosome dimers and how do they relate to recombination?

texts:
I am reading the book Molecular Genetics of Bacteria 4th ed. and I don't fully understand the concept/visual representation of dimer chromosomes. Consider the following quote (pg 35):

  an odd number of crossovers occurring between any 2 sequences on the 2 daughter DNAs in the dimer will resolve the dimer, but an even number of crossovers will recreate a dimer.

In panel 2, did another recombination event occur to yield 2 daughter chromosomes with the same sequences? The colors made me think they each might not have had their original complete sequence.

Thank you for the answer to my crossover occurrence question and their relation to dimer formation and resolution.


texts:
Is protein kinase-A located in the cytosol/cytoplasm of cells or in the plasma membrane?  Also, is it considered a receptor molecule since it is dependent on cAMP?

Any and all help is appreciated. Thanks!


texts: How do archaea relate to eukaryotes and bacteria?

texts:
I've read that they all share some genes, internal structure, and behaviour with each other, but with different degrees of overlap depending of what the function is. E.g., archaea have some eukaryotic and some bacterial function, and eukaryotes have bacterial function in the form of mitochondria and plastids.

However I'm finding the nitty-gritty of all this rather confusing. Could anyone please explain some of the detail for me as I can't seem to make any sense of this from reading Wikipedia, etc.


texts: A basic example of the interactions of 2 or more non-identical alleles leading to an advantageous outcome for an individual organism

texts:
Could someone help me out with a basic example of the interactions of 2 or more non-identical alleles leading to an advantageous outcome for an individual organism? Based on empirical research OR on a theoretical model.

An example of 2 or more non-identical alleles cooperating across replication iterations/generations between individual organisms would be even beter. I somehow find this more spectacular :)

Please let me know if I'm not mentioning enough elements to answer the question. It's a very broad question and I accept very broad answers - semantically and across scientific branches.

All the best,

Flo

Personal background: I am new to the scientific field of biology. I think I caught up on some of the basic principles of genetics, allellomorphs, loci and DNA replication and I've gotten interested in the workings of alleles.


texts: In tumor markers such as CA 125, CA 19-9 and many other, CA stands for Carcinoma antigen, but what about the number?


texts: Do Tardigrades preserve water or replace water?

texts:
If you find something funny in my argument, then please pardon me, as I lack knowledge of biology. I was reading an article titled as "Water Bears Can Replace All The Fluid In their Bodies With A Glass Matrix"

Being extremely new to biology, I am a bit confused. Do Tardigrades preserve water through this protein or entirely change their biological structure to flush away all the water present in their body and rely on these proteins? Does this mean that their bodies no longer contain water?

Thanks.


texts: How does human life expectancy change with age?

texts:
Human life expectancy tends to be given as a single number reflecting age at death from birth.

But life expectancy should really grow the longer you live, because, for example, once you hit your fifth birthday your chances of dying before age five drop to zero, so the contribution to the average life expectancy of all the people who died before age five shouldn't apply.

To put it another way, once you hit age ninety, your life expectancy calculated then and there should be at least ninety years even though that exceeds the life expectancy in every country on the planet, simply because you've clearly already made it that far.

Does life expectancy as a function of current age have a name, and what shape does this function typically take? Perhaps more interestingly, does this function take a significantly different shape in humans than in other animals (I'd expect infant mortality to significantly affect this for example)?


texts: What is the course of inter auricular line?

texts:
BACKGROUND: The interauricular line is the line connecting two auricles.

I wish to know the exact route through which this line passes. I want to be sure whether it passes through the parietal prominences, or in front of them.


texts: Can carnivores survive on a (processed) vegetarian diet? Why or why not?

texts:
There are many differences in for example the digestive system between carnivores, herbivores and omnivores.

It seems that in certain kinds of species adaptability with respect to diet is possible. What I have heard is that it is impossible for carnivores to survive on a non-meat diet.

Therefore I wanted to ask: Is it really impossible for a carnivore to survive on a vegetarian diet, even when the fruits/vegetables/plants are processed? I could see how their digestive tract would not allow for them to survive on grass, but what about certain kinds of nuts, mushrooms, or even processed plant based foods?

If it is impossible to survive on these diets, why?(With respect to either causes in their digestive system or substantial differences between meats and any type of vegetarian food.


texts: Are there any known examples of animals with air-conditioner type cooling?

texts:
Sweating is often poor at cooling, particularly on humans and animals with a lot of hair or fur because it collects on clothes and other coverings, trapping heat in while promoting the growth of potentially pathogenic bacteria. Additionally, sweating leaks out important electrolytes and water.

With that in mind, are there any known examples of animals that mimic an air conditioner's heat pump? In particular, consider a special channel where blood (or even better: a specialized cooling fluid) is pressurized (almost similar to inflammation) and pumped through a fin, then depressurized on the way out.


texts: What is this white-winged insect from Hong Kong?

texts:
When we were travelling in Hong Kong, near a bushy temple, we spotted some white-wing insects which we had never seen before. I sense it's a type of moth, but I have no idea what classification it is.

Tiny to 3-5mm
Mostly white on its body
Moving slowly
High volume in one area
Not so sensitive to external threats, e.g. no escaping when you try to hit them.


texts: Are oospores (of oomycetes) endogenous or exogenous? What are chlamydospores and in which class of fungi do they belong?

texts: I do know Chlamydospores are asexual spores but in which class of fungi are they seen often and are they exogenous Or endogenous?


texts: Why is the blood thick in Wet Cupping / Hijama

texts:
I have just witnessed the wet cupping procedure being performed and have questions regarding the blood that is seen in the cups. I understand there are no studies that show cupping is an effective treatment for many diseases as some claim it to be but my question is regarding the blood that is released.
The procedure aims to eliminate the 'bad blood' which leaves clean blood to circulate the body, the practitioner pointed out the difference between the clean and bad blood and there was a substantial difference in how it looked and flowed. The blood was very clumped up and thick and didn't flow well at all whereas some of the blood was a lot more fluid and was able to flow easily. I was told this runny blood is clean blood and is what we want in our bodies.
My questions are what is the thick clumpy blood and why is it like that?
Is it actually bad blood?
Thank you in advance!


texts: Extremely rare occurence of Heart cancer?

texts:
The occurrence of Heart cancer (similar, but not the same as Rhabdomyosarcoma) is extremely rare, about 1 per year according to MayoClinic. The reason for this rarity is explained to be the post-mitotic nature of cardiac muscles. Since they stop dividing early in the life cycle of humans and grow only by increasing in volume, they are very less prone to oncogenic activation events caused due to mutation as a result of an error in DNA replication (since they do not replicate their DNA as they do not divide).

Although I am not an expert in tumours and cancers, I think that malignant tumours in nervous tissue, i.e. brain tumours are fairly common, at least more common than heart cancer by several orders of magnitude. But neurons constituting these tissues are also permanently in interphase and hence do not divide.
 Moreover, secondary malignancies in Brain and nervous tissue is also much more common than secondaries in heart (rare) though metastatic secondary tumours, I believe, do not require oncogenic transformations in the host tissue. A metastatic fragment of a primary malignancy transported by blood is enough to cause secondary tumours.

How then these tumours (primary and metastatic-secondary) are more common in nervous tissue than heart, though both are post mitotic, i.e. permanently in interphase?

Here and here are a few links which give some basics of cardiac malignancies, though they don't address the question quite directly. The study here provides possible explanation of lack of cancer due to high oxygen content.


texts: Do different people have the same number of mitochondria in comparable cell types?

texts: e.g. will a lymphocyte in one person have roughly the same number of mitochondria as a lymphocyte in another person.


texts: What is the best way to find out what type of mold/fungi this is?

texts:
I have found some mould or fungi behind my bath tub panel. It seems to be the results of splashed water. I'd like to know what it is exactly.
I'm in the UK. If I need more specific data about what species this is etc what type of lab should I send it to/can you name one in the UK.
I already consulted some labs but they said they only examine mold which use their air test or urine test etc.  I'm thinking the easiest thing to do is just cut this out and send it to a lab but dont know which/where exactly.
Thanks.


texts: How do mutations with very little fitness benefit get fixed?

texts:
I have one little issue with evolutionary theory that I have not been able to understand.
Suppose genetic mutations happen from generation to generation. Nevertheless, from one generation to the next the mutation will present very small changes (I don't suppose a giraffe's neck would grow 10cm). If this were the case, then the advantages one gains from this mutation would be very small. So shouldn't it be the case that the mutation in the case of the giraffe and every other mutation for that matter present very very little advantage so shouldn't transmission of genes at this stage be random? If this were the case I don't see how natural selection could take place?


texts: Why do GPCRs pass exactly 7 times through the cell membrane?

texts:
7-transmembrane domain receptors or GPCRs are one of the most common receptors in biology.
They can be found in eukaryotic cells.
What is the significance of the number 7 here: why does it pass exactly 7 times through the cell membrane? What is so good about having it pass 7 times through it?
I can't find literature which goes deeper into this issue.


texts: What causes light to be brighter in the corner of the eyes?

texts:
I have noticed when in a dark room light and color seem to be brighter and more intense in the corner of my eyes. For example the light that comes from my digital clock seems like a dark pink when I look straight at it. But when I see it in the corner of my eyes it looks red.

What causes this?

Is this normal, does everyone perceive it that way?


texts: We have this science experiment on how to grow a bacteria, our teacher told us to use gelatin, beef stock, and sugar as an alternative for agar. I am confused on  why we need gelatin, beef stock, and sugar in growing a bacteria. What ingredient is in those 3 materials that can aid in growing bacteria?


texts: Duration of selection and survival of the fittest

texts:
I feel there is a part of the theory of evolution I'm not understanding correctly or maybe I'm missing it, but would like cleared up.

From what I understand, over time random mutations occur which in some cases provide an advantage allowing that animal to survive and reproduce. Its children will have that mutation allowing them to survive and so on over many many years until it evolves into a new species and / or the old ones become extinct.

For example the rock pocket mouse.

The part I'm getting stuck on is that unless these mutations happen instantly and in a large number, given its over such a big time scale how do animals who are not well adapted get enough time to evolve to survive?

Another example is fish that evolve to be able to "walk" out of the sea to escape predators.

If moving out allowed them to survive how did they get enough time to evolve and not be made extint in the time they didn't not have these limbs.

Hopefully I have explained myself clearly :)


texts: Why can't/don't neurons take up atmospheric oxygen or at-least dissolved oxygen (like amoeba does) to survive and do all life processes outside animal body ???


texts: Which Enzymes Catalyse the Deacetylation of Drugs in the Human Body?

texts:
If you would like more specifics seeing how I realise that this question is very broad and may be difficult to answer in general then hopefully the following will help you out:

I am particularly interested in acetyl groups bound by carbon single bonds
Drug metabolism in the liver particularly interests me
The drug paracetamol's (acetaminophen) deacetylation to p-aminophenol is of particular interest to me.


texts: Isotropy of sarcomere bands in skeletal muscle cells

texts:
As seen under a polarization microscope, the A-Band in skeletal muscle fibres is so named because it is anisotropic in its refractive index which is a characteristic of orderly crystalline structure. On the other hand, the I-Band is so named because of its isotropic nature, as far as its refractive index is considered, which is characteristic of Amorphous substances or substances which lack long-range order. Both are filamentous (as opposed to globular) in the sarcomere (Actin is present as F-Actin).

  But then why this difference in the characteristics of refractive index,
  which is indicative of order (i.e crystalline or amorphous?) in their
  molecular structure?

Moreover, is the H-Band anisotropic?

If not, then the anisotropy of the remaining part of A-Band must be a consequence of the relative arrangement of Actin and Myosin which are independently isotropic, and hence cannot give a possible isotropic arrangement.

If yes, then that indicates that the myosin filaments are anisotropic in themselves and actin filaments are isotropic. But, in the region of their overlapping (A-Band minus H-Band), the overlap is between an anisotropic (myosin) and an isotropic (actin) component which shouldn't be anisotropic because the randomness of actin filaments (i.e. its isotropicity) should make the entire configuration isotropic?

I am sorry if I am wrong in my understanding of isotropic and anisotropic characteristics, or if my question sounds too "physics-related", but this has been bothering me for quite some while now.

Here is a directly related question I asked on physics.se. It partly solves the problem of possible arrangement of isotropic elements to generate anisotropy.


texts: Is the neural area TEO distinct from the inferotemporal cortex?

texts:
I am finding conflicting literature with regards to the division of the inferior temporal (IT) cortex of the brain.
For some, I see that area TEO is equivalent to the posterior IT. Which would make TEO apart of IT.
For others, TEO is anatomically distinct from IT, but no mention of whether it is equivalent to posterior IT.
From my current understanding (please can someone confirm if this is correct...):
IT can be divided into posterior, central, and anterior.
Area TEO = posterior IT
Area TE = anterior IT
Because area TEO (posterior IT) extends into the occipital lobe, it is sometimes not considered apart of IT. But for some, it is.
Thanks!


texts: How exactly are gaps defined in genomics?

texts:
My understanding is that when sequencing a genome, "gaps" refer to fragments which were not sequencing in the sequencer.

Is this correctly? What are there other meanings to the term "gap"?


texts: Primer design for introduction of restriction sites flanking a gene of interest

texts:
I am wondering what the correct method for primer design to introduce restriction sites. Specifically between two methods.

1) Primer first partially hybridises to the gene, has a mis-match where the restriction site and extra bases are on the primer, then has a hybridised site following the restriction site, to DNA upstream of the gene.

or

2) Primer first partially hybridises to the gene, then completely dangling and non-hybridising has the restriction site and extra bases.


texts: Regarding the kingdom Animalia, which phylogenic tree is more common: Molecular Comparisons or Body-Plan Grades

texts:
In the picture below, which I obviously do not own:

it depicts two different phylogenic trees, one which is based on molecular comparisons and another one which is based on body-plan grades. My question is which is more common or accepted in the current Biology world?

Image reference: http://www.zo.utexas.edu/faculty/sjasper/images/32.12.gif


texts: Given that the mechanism of natural selection is sensitive, how do species survive in an evolutionary midway? The ability to breath in air requires complex protein systems. An animal that is developing these organs would not be able to utilize its function until it fully evolves. While it doesn't, wouldn't the wasted resources used in growing half-developed lungs be.. wasted? Or is all evolution continuous?


texts: What roles do circular connection structures play in the brain?

texts:
Most neural network simulations are strictly linear, one reason being they don't want to deal with circular connections (and infinite feedback loops if you dont have the right mechanisms). You can deal with them at the cost of some efficiency, but I'm curious about whether in the real brain, circular connections play an important role, or are they really not necessary?

To be clear, I mean any structure where you have a Neuron A, Neuron B, and Neuron C (or a thousand more) and the structure is similar to A > B > C > A or generally at some point Neuron A ends up having a path where its own output can lead back to itself.

What roles do circular connections play in the brain? Or more simply: Are they useful and what are a few reasons why?


texts: Is there a difference between endorphins that are released while physical activity and sex/masturbation?

texts:
I observerd myself and I can identify two different types of "happines".

First - called by me - After Pleasure :

Occurs AFTER (and last long) long activity that require from me engagement focus and effort  for example :

running 16KM
learning for an hour things that I think are worthwhile
reading book
generally any mental or physical activity

Second - called by me - During Pleasure

Occurs DURING (and last short time) activity that DON'T require any engagement, focus or effort, for example :

masturbation
eating sweets
eating tasty things in general
having hot bathing time
watching funny videos/TV

I wonder is there any scientific distinction between those two states of my body and mind. And assuming that endorphins are the hormones are responsible for the "oh-good" state, are different kind of endorphins are released while taking this 2 different activities (like studying for 1hour and masturbation) ?

Thanks for an answer in advance.


texts: Decreasing signals in assay measurements

texts:
I'm working with a calcium assay to study the effects of different virulence factors. The assay works, but from day to day the signals of cell lysis go down. Unfortunately, I haven't found an explanation for why this is happening.
The particular assay I use measures cell lysis. The virulence factors I use cause pore formation and lead to a calcium influx (from the buffer). Esterase proteins activate the fluorophore and need calcium. Increase in cell lysis leads to an increase in signal.
As I already mentioned my signals are dropping (from day to day). But I don't know why.
Have you got an idea of what could lead to such effects?
Here are some factors that might be involved.

The virulence factors lose their activity? (I don't feel like that this causes the problem because new stocks also show a decrease in activity, and also the signal from the positive control decreases. I would say it decreases in a similar ratio. The positive control is triton.
The dye loses its activity? The bottle is normally stored in a freezer. I just take it out for the assay. Before I use it, I place the bottle on a shaker for about 30 minutes. I just open the bottle for a few seconds and then put it then back in the freezer.
The plate reader is broken or the reading protocol has changed? I already checked the protocol and every thing is the same as in the beginning. Coworkers get the same results with the same plate reader as before. So I guess, this should not be a problem.
The buffer gets destroyed from the procedure? I store it in the freezer and take it out and put in a waterbath. After I used it I place it back in the freezer. I carry out this procedure every time, can this lead to negative effects? The medium contains calcium, can something happen with it (Calcium plays an important role in this assay)? A colleague already told me that he stores his buffer in the fridge not in the freezer, and he didn't got such effects. But perhaps it's not the only thing he does different..
The cell number changes? The negative control does not change over the experiments, and the signal from it is still higher than the values from the blank. But i will check that.
Could my cells cause problems? They look still good under the microscope.


texts: Are nerves and/or neurons able to grow and repair after damage, but not regenerate? Is this specific to humans? I have heard of people being paralyzed, but after much therapy are able to use their legs again. Is this just through the creation of new connections from healthy nerves, or is there nerve repair to an extent?


texts: What is this insect? 6 legs and red body

texts:
I'm in Brazil, southeast region, urban area. I've found these 6 legged insects with red bodies and black heads. They have long antennae (about as long as their limbs) and they walk around like ants, but slower. Their bodies are about 1.5mm in length.
I have also found a cluster of what I imagine are eggs they laid or got out from (there were 5 or so next to them last night).
Can someone identify them?


texts: Are most pathogenic bacteria facultative anaerobes?

texts: I know that S. aureus and most gram-negative rods are facultative anaerobes. In terms of number of species, are most human pathogen-associated bacteria facultative anaerobes?


texts:
You can't plant the leaves, you can't plant the fruit, but, if you plant the part where leaves and fruit meet you will grow a whole pineapple plant.

The part of the pineapple where the leaves meet the stem is the point from which the whole plant seems to form. Cells below seem to become fruit and fruit skin, cells above seem to become leaves. If you look at a cross-section of this part of the plant you can see the way that the cells seem to move outward from this point.

(1)But is that really how it grows? Are the new cells added from the center or do new cells get added to the leaves at the tips and in the middle of the leaves?

(2)I know some orchid roots grow from the tip... but is this the case for all roots?

(3)I noticed that some lemongrass in my worm compost bin has grown roots! So, I transplanted it outside. Maybe I can grow lemongrass. Again, it was the part of the plant where the roots met the leaves that still had life in it.  This seems like a very powerful part of the plant. Is there a name for the part of a plant from which everything else grows?

UPDATE: http://en.wikipedia.org/wiki/Meristem

This is what the regions is called! But I still want to know if the plant "pushes" out the leaves from this central point or not... and are all root like orchid roots that grow from the tips?


texts: Expected number of times a mosquito bites (per night)?

texts:
Imagine you are sleeping alone in your bedroom and there is a (female) mosquito in the room wanting to feed on your blood. I read here the mosquito will try to keep biting and feeding on you until its belly is full.
Question: What are the expected number of times the mosquito will bite you if you do not actively avoid it? (For example, in the case you were sleeping). However, I imagine this might vary with the mosquito species.
In particular, I am thinking about strategies aiming for minimizing the number of the mosquito bites: would it be feasible to let the mosquito bite you once and suck your blood until becoming fully feed?


texts: Keep in mind I'm not asking what the function of tears are or what causes tearing,(there's a lot of good answers on it already). My question is: how exactly is the tear gland able to actively push out fluids when it receives a stimuli? What exactly is the tear gland doing and how does it produce tears? How does it start and stop?


texts: Why Differential equation is not a good way to model chemical reaction networks

texts:
I'm a computer scientist and mostly code and have worked with Boolean models of cell level molecule transfer. Now i'm reading about the Biological pathways and modelling chemical reaction networks / Actions / Post translation modification and have no idea about differential equations.

What are the  pro's and con's of modelling these situations as differential equation Vs Boolean Vs Rule based approach.


texts: Does brain size matters for the intelligence of an organism?

texts:
It was shown in a local TV show that larger the brain, larger the intelligence of that organism.

Does that mean if more number of neurons present in the brain canit helps in improving the intelligence of that organism?


texts: Do plants refix some of the carbon dioxide in the Calvin cycle that they produce through cellular respiration?

texts: Plants do cellular respiration and release CO2 into the air, but does the plant also use some of this CO2 to do the Calvin cycle? Or does all the CO2 required for the Calvin cycle come in through the stomata?


texts: Why do the capillaries have a lower blood pressure than the arteries even though the capillaries lumen is much narrower. Wouldn't the narrowness of the blood vessel increase the pressure? Also the arterioles have an even larger lumen than the arteries so shouldn't the capillaries have a larger blood pressure than them as well?


texts:
Why does sodium-potassium pump consume about 2/3 energy of a cell ?

A.maintains appropriate membrane potential

B.helps in co-transport

I think it should be A.


texts:
In the late fall, bats hibernate in clusters with many bats pressed together and holding on to one another. Which of the following supposed advantages of huddling behavior is, in reality, not true?

Any heat generated by any bat is shared by other bats.
Less surface area is exposed to the environment.
Huddling behavior decreases the amount of food needed for bats to stay warm.
In this configuration, less heat is needed for each bat and, therefore, each bat requires less food.
Huddling behavior helps bats stay warm while they feed.


texts: How do white Caladiums perform enough photosynthesis to support their mass?

texts: In some white caladiums, there is less than a square inch of green space spread over the whole leaf. How do these plants perform the photosynthesis necessary to support the large leaves, the roots, the flowers, and build a corm?


texts:
I know that if there is too much CO2 in the air we will have too much greenhouse effect.

I would like to know if there is too much CO2 in the room, something like 3% while there is also more that adequate oxygen for us to breath. will we live or die? why?


texts: Structure of fitness landscapes in the NK model

texts:
The NK model of rugged fitness landscapes consists of $N$ sites where fitness contribution of each site depends on its state $\{0,1\}$ and is epistatically affected by $K$ other sites. When defining the model, Kauffman & Weinberger (1989) stressed that:

The actual structure of [fitness] landscapes, although knowable is currently unknown

They then go on to assume either epistatic interactions are with adjacent sites in a linear ordering or at random, and that fitnesses are assigned to each of the $2^{K + 1}$ epistatic combinations at each site uniformly at random in $[0,1]$. Although it is definitely possible to justify this random generation, it tends to produce a very structured fitness landscapes, that although rugged (for high $K$), has a very regular distribution of local fitness optima. As a computer scientist, this assumption of an arbitrary random distribution over possible NK landscapes seems very misguided. I would be more comfortable with a worst-case analysis on a "reasonable" (hopefully as determined by experiment) subset of possible NK landscapes.
What is known about the typical structure of NK landscapes in biological domains? Also, are there examples of biological papers that do a worst case instead of an arbitrary random analysis on some non-trivial subset of landscapes? The only example I am familiar with is the gadgets used by Weinberger (1996) to show that the unconstrained model is NP-hard, but that is a trivial subset (all possible landscapes) and not of biological interest.

References
Kauffman, S. and Weinberger, E. (1989) The NK Model of rugged fitness landscapes and its application to the maturation of the immune response. Journal of Theoretical Biology, 141(2): 211-245
Weinberger, E. (1996). NP-completeness of Kauffman's N-k model, a Tuneable Rugged Fitness Landscape. Santa Fe Institute Working Paper, 96-02-003.


texts:
I have been reading:

  William B. Whitman, David C. Coleman, and William J. Wiebe, "Prokaryotes: The unseen majority", Proc. Natl. Acad. Sci. USA 95, pp. 6578–6583, June 1998.  [Full Text] [PDF]

wherein they estimate the number of prokaryote cells on Earth to be of the order of $10^{31}$.

I can't seem to find any equivalent data for eukaryote one-celled life. Are there any estimates for the number of one-celled eukaryotic living things on Earth? Do any other estimates confirm or tell against the reference I have cited above?


texts: Why is the capirally electrophoresis rarely carried out?

texts:
I'm a student at the university in Japan.
I search details and advantages with each electrophoresis.

I think the capirally electrophoresis has much nice method at the points of resolution, rapidity and so on. However, just my thought, there are not very many of papers using it.

I have asked at a Japanese site (not professional one), and the answer is on cost. But no sites explain so.

Please give me a help for this confusing.
Thank you for your reading.


texts: ID Sunbird in Oman - White, Dark Grey, Yellow

texts:
Some extensive web searching has not helped me find this bird I discovered in my travels. They were flitting too fast to get a decent picture, but here is the best description I can obtain from memory:

Dark Grey from their head to their back. Their wings looked black but, as I said, they were flying about. Throat and breast were pale, probably white. Belly and vent were bright yellow. Their beak was a similar shape to the Purple Sunbird. They were taking nectar from bushes bordering a house which had small white flowers.


texts: Advantages of bisexual reproduction over asexual one toward species promotion?

texts:
Are there any advantages of bisexual reproduction over asexual one towards species conservation and promotion? Do animals that have two or more sexes have more chances to reproduce?
Does anybody had a quantitative account of this fact?


texts:
I read that opening in our face like nose and eyes are one which get us infected with numerous communicable diseases like  cold , flu ebola etc.
Both these organs have preventive mechanism like nose hairs, eye lash , etc.
Which one of eye and nose does protect human better from airborne virus and bacteria?


texts: Are there other species that get nosebleeds? If so, do they occur for the same reasons that humans get nosebleeds? How would an animal stop a nosebleed?


texts: Legality of doing private or scholastic virology with human pathogens?

texts:
Is it ok for a student, say a graduate student in biochemistry, to do amateur virology using potential human pathogens?

For example, lets say the student gets a cold and tries to isolate the virus causing the cold. Is it ok for the student to do that in a school lab? How about a home lab?


texts:
I live in France. I've just found several (8) of these in my living room, close to an oak cupboard and my Christmas tree, a cut Abies nordmanniana (supposedly grown in France).

Their body is around 5 mm (1/5 in) long. On the tissue they walk easily (1st picture), but on the glass of the jar they can't even stay upright and fall upside down (2nd picture).

(At first I was afraid they would be woodboring insects, which I've never seen, but WP taught me the latter are beetles, and these beasts aren't beetles, right?)


texts: Dealing with heterochromatin during DNA replication

texts:
Heterochromatin are present along the chromosome (uncoiled state). With the highly-condensed structure relative to euchromatin, RNA polymerase cannot get into the DNA base pairs in heterochromatin and starting transcription.
Question: During DNA replication, heterochromatin are also required to be replicated since they are part of the chromosome. Therefore, I would like to ask whether topoisomerases themselves can unwind this extreme super-coiling or other enzymes / mechanisms are involved in unwinding heterochromatin during DNA replication.
(I have this question in my mind is because I am not sure whether the same unwinding mechanism from topoisomerase can be applied to the super-coiling formed in the already condensed heterochromatin compared to euchromatin)
Thank you.


texts: $F_{ST}$ and the genetic variance in metapopulations

texts:
From this video (21'15''), the speaker gives the following formulae in order to calculate the between and among populations genetic variance from the $F_{ST}$:

$$V_{Among Pop} = 2 F_{ST}V_G$$

$$V_{Within Pop} = (1-F_{ST})V_G$$

, where $V_G$ is the total genetic variance of this population if it was well mixing. $V_{Among Pop}$ is the variance among populations and $V_{Within Pop}$ is the variance within populations.

In this same video, the speaker defines $F_{ST}$ as:

$$F_{ST} = \frac{\text{Var}(p)}{\bar p (1-\bar p)}$$

, where $p$ is a vector of frequencies of a given allele and $\bar p$ and $\text{Var}(p)$ are the mean and variance of this vector.

For example, consider a metapopulation made of 4 subpopulations. The allele frequencies in these 4 subpopulations are p=[0.2, 0.5, 0.8, 0.3]. $\bar p$ is the mean of $p$ ($\bar p = 0.45$) and $\text{Var}(p)$ is the variance of $p$ ($\text{Var}(p )=0.07 \space$).

Can you help me to make sense of the formulas for $V_{Among Pop}$ and $V_{Within Pop}$?

Can you prove these formulas? I would expect that $V_{Among Pop} + V_{Within Pop} = V_G$ but it doesn't! Maybe the issue has to do with the fact that $V_{Within Pop}$ as defined above fit to haploid population and not diploid populations. Then, I would expect that for diploid populations $V_{Within Pop}$ becomes $(1-2F_{ST})V_G$. Is that correct? Just in order to make it more general, how do you extrapolate these definitions for a tetraploid population? Also maybe I misunderstand the meaning of $V_G$. Is the variance within population the sum of the within populations variance or is it the average (or something else)? Thanks for your help!


texts: Horizontal gene transfer versus convergent evolution

texts: There are several often noted examples of convergent evolution (eyes, bat/bird wing evolution etc.)  How do we rule out horizontal gene transfer in these cases?


texts: Identify this larvae that lives on a musrhoom?

texts: I was in the forest near the Rhone river in France and I uncovered some mildewy wood bracket fughi (Ganoderma) on a fallen willow tree. It was a scene from a sci-fi film. some arthropod larvae of 2-3cm had built cocoons within a web, and the cocoons were empty and the larvae were wondering around on the mushroom.


texts: Draw simplified phylogenetic tree for kids

texts:
I need to draw simple, phylogenetic tree for kids lecture.

I am looking for an online tool where I can enter organisms (e.g., human, wasp, fungus) and get figure of a phylogenetic tree. Tree should be based on how close those organisms are (I don't need genome alignments).

Similar figure producing tool would be perfect.


texts: Can replication occur if DNA is methylated?

texts: Can a methylated strand of DNA be replicated without removing methylation? Does it make any difference if the strand is methylated or not (during replication)?


texts: Is there a correlation between total neurons and intelligence?

texts:
Thanks for looking.
First off, I am not a biologist, just a curious layman, so I apologize in advance if this isn't a "good" question.  Please don't downvote me into oblivion.
I read today that the human brain has about 100 billion neurons and that got me wondering: is that number pretty standard for everyone or does someone like say,
Einstein, have many more neurons than this daft poster.
Question
Is there a correlation between total neuron count and intelligence, or does intelligence depend more on the way neurons are used--or some other factor like previous experience--rather than their total count?
Can this question be answered?
There are two very valid points-of-view posted as answers below, but it sounds like we simply don't have a solid answer to this question at this point in time, so I hesitate to select a "correct" answer.


texts: How does the "heat vision" of some snakes work?

texts:
Some snakes have an infrared sense which is used to track warmblooded animals.

How does that organ work? And would a similar organ be possible in a warmblooded animal?


texts: What does 'direction' mean in the statement "mutations are non-directional"?

texts:
I was reading the Mutation theory of De Vries; there I encountered this following statements

  Mutations are discontinuous, random & non-directional.This is in contrast to Darwinism where variations are continuous & unidirectional.

and

  [Hugo deVries] believed that it mutation that causes evolution and not the minor variations (heritable) that Darwin talked about. Mutations are random and directionless while Darwinian variations are small and directional. Evolution for Darwin was gradual while deVries believed mutation caused speciation and hence called it saltation (single step large mutation).

Could anyone please explain what direction means in the two statements above?


texts: Is there an equivalent to "Fields Virology" for Bacteria?

texts:
I've gotten a staggering amount of use out of my copy of Fields Virology as a general reference for "getting me up to speed" on whatever pathogen I'm currently looking at. I don't know of a similar type of reference for bacteria, but I only became aware of Fields as I was moving out of the field, rather than into it, so it's possible I've simply never heard of a suitable reference.

Any suggestions?


texts: Measurement equation of Tree-Step pathway model

texts: I am not specialist in biology but I want to test a parameters estimation method (based on Kalman filter) on the Tree-Step pathway model, but I cannot find a document that gives the measurement equation of the Three-Step Pathway model (Moles et all 2003, Parameter Estimation in Biochemical Pathways: A Comparison of Global Optimization Methods"), can someone give me some references?


texts: Are humans getting taller, shorter, staying the same height?

texts:
This post stems from this question, and specifically this article, which was provided within a response.

From what I gathered, the article attempts to make a correlation between the size of a creature and the length of its gestation period, with there being a linear, positive correlation.

This then led me to the question of, have homo sapiens more or less maintained the same [average] height since the advent of our species? In my searches I was able to find a few articles (e.g., here), however, they mostly only consider height changes within the past 100-200 years. Ideally, I would like to know if there have been significant changes (>13 cm) in average height for homo sapiens over the past 150,000 to 200,000 years.


texts: What is the difference between Molecular and Cellular tolerance?

texts: Although I've read that there are three types of tolerance, molecular cellular and behavioural, I cannot seem to find any mechanism of cellular other than desensitization of receptors. If someone can clear it up, or inform me that cellular tolerance is not a thing, that would be much appreciated <3