texts: Is it essential to add cholesterol to agar or liquid culture for C. elegans?

texts:
In preparing agar plates with NGM, and also liquid cultures for growing c elegans, how essential is the addition of cholesterol and heavy metals? I have prepared both. I can't notice any obvious difference and I hate having to add all these supplements.

I'm using yeast extract and peptone as the primary components of the base.

Isn't this just supposed to be a moist semi-soft substrate for them to crawl around, their nutrients come from the bacteria they eat.


texts: Why can't a genetically sound human stay alive for an indefinite amount of time given all the ideal conditions?

texts:
I have read that even if we can control our food and lifestyle and keep things as ideal as possible, there are other factors beyond our control like effects from neutrinos passing through our body that would accumulate over time, and may cause harm. More over, Earth's natural radiation, and the Cosmic background radiation may as well play a part.

I wonder what if we somehow removed these as well, will one be able to live forever?!
I have heard people say that this is an impossibility, but I wonder why?!

Thanks.


texts: How to interpret this cuffcompare result? Sensitivity over 100?

texts:
I run a cuffcompare:

cuffcompare -r transcripts.gtf TransStandard_1.0.gtf

I got the following result:

#= Summary for dataset: /home/tedwon/Sources/QA/data/trans/TransStandard_1.0.gtf :
#     Query mRNAs :     165 in      78 loci  (157 multi-exon transcripts)
#            (69 multi-transcript loci, ~2.1 transcripts per locus)
# Reference mRNAs :     165 in      78 loci  (157 multi-exon)
# Super-loci w/ reference transcripts:       77
#--------------------|   Sn   |  Sp   |  fSn |  fSp
    Base level:     100.0   100.0     -       -
    Exon level:     110.6   110.6   100.0   100.0
  Intron level:      99.6    99.6    99.6    99.6
Intron chain level:     100.0   100.0   100.0   100.0
  Transcript level:     100.0   100.0    99.4    99.4
       Locus level:     100.0   100.0   100.0   100.0

 Matching intron chains:     157
          Matching loci:      78

      Missed exons:       0/872 (  0.0%)
       Novel exons:       0/872 (  0.0%)
    Missed introns:       3/756 (  0.4%)
     Novel introns:       0/756 (  0.0%)
       Missed loci:       0/78  (  0.0%)
        Novel loci:       0/78  (  0.0%)

 Total union super-loci across all input datasets: 78

What I don't understand is that why the sensitivity and specificity for the exon level are over 100? The values in this example are both 110.6. Shouldn't it be from 0% to 100%? The website doesn't address it.


texts: I have a long list of uniprot IDs. How can I get the mass of the "canonical" isoform for each? Ideally from some Python library.


texts: Guanidium salts like (G-isothiocyanate) disrupt the hydrophobic interactions inside a protein or nucleic acid and denature it. What happens when hydrophobic interactions in DNA are broken? (I don't think it should get ssDNA because guanidium doesn't break hydrogen bonds within molecules)


texts:
It is a commonplace of my friends and relatives to remark that a young child (younger than 3 years) has had a recent "growth spurt". The underlying assumption is that young children do not grow taller continuously and steadily,  but have periods of rapid growth between periods of slow growth. But is that assumption true? I'm sceptical; I'm inclined to believe that growth is steady, and the idea of growth spurts is a flaw of perception.

So, what research have I done so far on this question? I've seen the height-age charts for children, and they are smooth, so there are no growth spurts synchronised across all children. But that smooth averaged growth could result from the average of many non smooth growth rates. So the question is about when considering a single child. A web search about children's growth spurts shows numerous parenting web-sites that assume that growth-spurts happen, without asking whether growth spurts actually happen. I found an old press release from Emory University about some research supporting the idea, but no better information.


texts: Why do (some) cats chase their own tail?

texts: Is this just playful behaviour or are they unaware that it's their own body part ?


texts: Why do wasps (Vespula vulgaris) build a new nest every year?

texts:
I have been searching it for a while, and i haven't found an answer, why do common wasps (Vespula vulgaris) create a new nest every year instead of using the previous one if the old one is still functional.
Is there something in the nest that in somehow "expires" and will be an impediment to reuse?
Does it have something to be with the orientation due to the earth rotation?


texts: Insect that has evolved to recognize carnivorous plants

texts: Obviously in a biome consisting of high density of carnivorous plants any insect that can recognize these plants or at least recognize organs associated with carnivory will get fitness advantage. So it seems a very natural thing to evolve from insects point of view. Has it happenned? If yes, what are some of the examples? If not, why it hasn't happened?


texts: I have found a lot of content on the patellar reflex, but I cannot find any studies on how fast the reflex is, from onset of stimulus to innervation of muscles.  Does anyone know of either a study or at least a ballpark number for how fast that reflex is?


texts: What is the difference between transverse section and longitudinal section?

texts:
Can anyone explain the difference between transverse and longitudinal section?

Or are they the same?


texts: Exhalation in human breath, through mouth or nose: which is most usual?

texts:
Until now I believed that breath exhalation through the mouth is common for most human beings, and this fact is implicit in several technical contexts of which I can think (sports, music, medical checks...). But recently a friend was surprised when I claimed this, and conducted a small poll around himself, giving a 100% of people inhaling and exhaling both through their noses in normal breath (then I was surprised!).
This issue is not without practical interest in these COVID-19 days, because when using a surgical mask (which filters the air going out but not the air coming in), people exhaling from their mouths and not covering their noses with the mask are still giving more or less the same protection to others, so if most people actually exhale through the mouth, this common "faulty" usage would actually not be so dangerous.
Can someone point to any scientific paper having evidence or statistics about normal mouth exhalation against normal nose exhalation?


texts: Confusion over equations for population's heterozygosity vs. heterozygous individuals

texts:
On page 24 of Gillespie's Population Genetics, 2nd ed, an equation for $H$, the probability that two randomly drawn alleles are different by state, is given.

$H$ is stated to be similar to the heterozygosity of the population, which I guess is expected to be $2pq$, where $p$ and $q$ are frequencies for different alleles. $ H′=(1−1/2N)×H$

On page 23, $H_t$, the probability that an individual chosen at random from the population after $t$ generations of random mating is heterozygous, is given :
$$H_t = H_0 \times (1-\frac{1}{2N})^t$$

For a current time $t$, are $H$ and $H_t$ measurements of the same thing, or are they different ?

I interpreted them as being the same, because drawing two alleles at random is similar to drawing a diploid individual at random.


texts: How do you knockout an E. coli gene without disrupting the rest of the gene cluster?

texts: I'm familiar with the method to build Keio collection using single-gene deletion with an antibiotic cassette. However, what happens when there are gene clusters or overlapping ORFs and you still only wish to knockout a single gene?


texts: Explain allelic complementation at molecular level

texts: I know that Allelic complementation is a phenomenon where two recessive loss-of-function allele generate a functional gene product by compensating each others' defect. But I don't get how do they compensate each others' defect.


texts: Small non-coding RNA (sRNA) vs. micro RNA (miRNA)?

texts: What are the differences between micro RNAs (miRNA) and small non-coding RNAs (sRNA)? Are these two terms used interchangeably?


texts: Relation between respiration and concentration of citric acid

texts:
A and B are 2 reactions.

If there is an excess availability of citrate, then which of the above reactions will prevail?

I know that citric acid is formed when oxaloacetic acid reacts with acetyl coA. But how does concentration of citric acid influence the above reactions


texts: What is the energy consumption of the brain?

texts: What is the energy consumption of the brain, and is there a difference in consumption when waking and sleeping?


texts: How do elk know how long their antlers are?

texts:
They fight to compete for females, particularly those with similarly sized antlers. How would an elk know that its antlers are similar in size to another elk's if they can't see how long their own antlers are?

"The stag with the biggest antlers asserts dominance by showing them off and occasionally fighting with them."

Source: Natural Curiosities Ep. 4


texts: I usually take my protein sample 0.8ml and sample buffer(2X) 0.2ml for my sample preparation in SDS PAGE. Am I using correct proportion? my protein sample concentration is 4.1mg/ml. What is the standard protocol?


texts:
A genetic variation is found in this chromatogram:

It says that the "reference sequence" is the top line and that I can use the general genetic code to find the reading frame.

I can see that there are two N's instead of a G and a C. However I don't know what this means. I'm also not sure how I'd find the reading frame? I suppose I could look for a start and stop codon but I could read them both ways?

Last question: Is this change likely pathogenic? I'm not sure how to classify a variation as pathogenic or not.


texts: Paper shows 2 hours of high humidity and hot temperatures kills corona virus, does this stop the spread of the virus?

texts:
I found this paper (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2863430/) which says these corona virus strains live for months at 4 degrees C, 20% relative humidity. But at 40 degrees C and 80% relative humidity, 90% of it dies in 2 hours.

For example, if people set the furnace to 40 degrees and humidifier to 80% relative humidity for a couple hours each day, does this stop the spread of the virus?


texts: Do plants need O₂ to consume energy they've stored via sugar?

texts:
This question came up as I work my way through the answers to another question I just asked.

My understanding is that plant photosynthesis looks something like this (though with lots more going on under the hood):

$$\ce{6 CO_2 + 6H_2O + light -> C_6 H_{12} O_6 (sugar) + 6 O_2}$$

(source)
and that the primary functions of the sugar are to store and transport energy. If that's true, then there's something fishy about the familiar view that plants need CO2 to breathe and produce O2, while animals need O2 and produce CO2. Doesn't a plant need just as much O2 as an animal would when it (the plant) gets around to consuming the sugar it has produced? Doesn't consumption of the sugar take you back to the original reactants?


texts: How do animals decide what to eat and what not?

texts:
I want to know this in particular about animals that no longer eat what they used to eat. The best example in my opinion are chickens. Chickens are often held to eat all kinds of food we would otherwise throw away. Most of this, they would never find in nature.
Chickens almost eat everything, but there are things they don't. Also, they often have a clear preference for some food.

How can they differentiate this food? Do they use smell? Looks? How can they know smells of food they never had before?


texts: Weighing 2 vertical halves of the human body

texts:
I had this thought while bathing:

Assume a perfectly developed physical human body and anatomy in terms of size, dimensions and proportions. In theory, if I cut the body vertically into two exact halves from the center of the head downwards, would the two halves weigh the same?

I tend to think that the 2 halves would weigh differently, and if so, I find this quite interesting because it is strange to me that our body would - perhaps unecessarily - evolve in such a manner that requires it to balance itself on a symmetrical skeleton.

Are there any topics that touches on this... phenomenon?


texts: Why do dogs come in all shapes, but cats are generally all the same?

texts: Minus hair and fur, cats (the domestic kind) seem to be just scaled versions of the same thing.  Dogs on the other hand can have long necks, short necks, long bodies, short legs, long ears, short ears.....


texts:
I have a list of differentially regulated genes from a high-throughput experiment of the human genome. I would like to find out which of these genes are transcribed by a RNA polymerase III and which of them (probably most) are transcribed by the RNA polymerase II.

I have downloaded some Chip-Seq tracks for polymerase II and III and some GO categories which apply for the RNA polymerase III transcription.

I have also tried the biomaRt repository to search for these mentioned GO categories, but I can't really find substantial results.
For example I have the gene RN7SL1 which according to the literature is transcribed by PolIII, but I'm not able to find any repository which also says so.

Is there any (better) way to search for this kind of data/annotations?

thanks a lot
Assa

PS.
I am not sure, if I have found the correct GO categories (e.g. GO:0006383 - transcription from RNA polymerase III promoter). So are there any better one?


texts:
I was cleaning out my pool with a leaf scoop the other day and found a small object, which I assume to be a sort of skull or cartilaginous structure of something that had died.

I live in Sydney, Australia and in the pool there were a large quantity of water boatmen and dragonfly nymphs.

What does this skull belong to, and what is the purpose of the hollow, bulbous mounds next to the eye sockets?


texts: How optimal are the distances of voltage-gated ion channels on axons?

texts:
In both myelinated and not-myelinated axon segments ("axons" for short) there are theoretically maximal distances of voltage-gated ion channels beyond which propagation of the action potential would break down because the potential arriving at the next ion channel would be too weak to open it. (In myelinated axons it's about the distance between the nodes of Ranvier.)

In not-myelinated axons this distance is smaller, in myelinated axons it is greater.

Compared to these theoretically maximal distances there are the real distances between the ion channels (smaller for non-myelinated axons, greater for myelinated axons), resp. their mean distance along the axon.

My question is: How strongly do the real (mean) distances of ion channels deviate from the theoretically maximal ones? An axon with greater mean distance than the maximal one would not work very well, an axon with a significantly (and unnecessary) smaller mean distance would waste resources and would possibly produce distracting interferences.

Side question: What's "the" standard deviation of the mean distance of ion channels (nodes of Ranvier)? ("The" because there may be differences between types of neurons/axons.) Are there numbers available?


texts: I'm 17 and I'm about 160 cm and my weight is 47 kg . I just want to know if I will still grow taller ?


texts:
A friend found this stuck to his insect screen today.
He said it felt like dust.
This wasp/bee was alive.
Location is Germany.
Is this a nest?

First look:

After peeling it open:


texts: Can rats pass on memories of a maze to their offspring?

texts:
A friend of mine told me once about a documentary movie he saw some years ago. On this movie he saw scientists talking about particular experiment. This experiment involved rats and probably electrical traps. The rat had to get to the cheese, there were traps on the shortest route to it, and obviously it got shocked few times. What is interesting is that my friend says that when they took its offspring (probably born later) they avoided those traps.

I'm aware that its not how "genetic memory" works. Its not memory of individual, but of species (so it requires evolution). This is what I'm trying to explain to him, but he says "he knows what he saw".

Anyway maybe someone here is aware of such an experiment. I believe that he is wrong about something (or conclusions drawn where changed later), so I would like to find out more about it.

To sum up:

Its not Tryon's Rat Experiment
It involved: rats, traps (probably electrical), more then one path to cheese, rat's offspring and some sort of memory/learning amongst rats.


texts: How do you estimate global species richness?

texts:
I know how estimates of species richness in a small area are made. But how do you estimate the total number of species on a global scale?

One example of such a method can be found in Mora et al. 2011.


texts: What is known about the genes responsible for inherited facial features — the family resemblances that are so recognizable? Take for example a particular shape of nose: which gene or genes make it snub or Roman?


texts: How to set the phenotype in GWAS analysis?

texts: In the GWAS analysis, my animal sample phenotype is whether an individual dies or survives. And I have every sample death time. How do I set the phenotype in GWAS analysis?


texts: How similar are Circulating Tumor Cells and Cancer Stem Cells?

texts:
Circulating Tumor Cells (CTCs) are linked with metastasis and their presence can be used to indicate the onset of metastatic cancer. Likewise, the Cancer Stem Cell (CSC) hypothesis suggests that tumorigenic stem cells are the source of cancer. However, microscopy experiments and cytometry have suggested that the morphology of CTCs and CSCs are quite different. Essentially, we have not been able to find Circulating Cancer Stem Cells (asides Myeloma since they are circulating anyways).

My question is how similar are these cells? If they are different, is relapse caused by the CSCs from the primary tumor or CTCs in metasises that have become CSC-like?


texts:
I saw a crab walking home from work the other night. We're by a river, but I was probably 500 feet away from the river when I saw this one. I apologize for the image quality, all I had was my terrible Ipad camera and no flash. I have provided the original image and one with brightness and contrast modified to make the crab easier to see. It's about 2.1 inches from leg to leg, I threw a 500 yen coin by the crab as a reference, but cropped it from the image.

I am located directly across from Haneda airport, which is on Tokyo bay. The river is close enough to the ocean that we get tides. I'd say the river level varies by as much as a meter, and there are many many crabs on the exposed riverbed at low tide. But again, this crab was far away, and would have needed to climb a three foot tall vertical wall at the river's edge.


texts: Why do most theories assume "only" sexual reproduction can cause genetic diversity?

texts:
The reason cited for sexual reproduction trumping over asexual reproduction broadly relies on the advantages of genetic diversity.

This completely overlooks the fact that a mutant which is able to reproduce asexually with some amount of genetic variation (editing, randomizing etc) would have more inclusive fitness?


texts: Does tremor frequency generally increase as Parkinson's disease progresses?

texts:
I've been trying to research this question, but most if not all the on-line journals require costly subscription, and the studies that are posted look at tremor frequency with regards to other factors.

My question has to do with the tremor frequency, starting at early onset to later stages of Parkinson's disease - over the course of the disease, and without drug treatment (such as L-dopa), does the tremor frequency generally increase?


texts: Can neurotransmitter depletion cause short-term drug tolerance?

texts:
I'm curious to know if neurotransmitter degradation factors into drug tolerance and neural conduction and, if so, to what extent. As I recall from textbooks I read as an undergrad, one mechanism of drug tolerance works by increasing the necessary thresh-hold at a synapse such that larger concentrations of neurotransmitter or more-frequent action potentials in the upstream axon were required to depolarize the membrane and propagate the signal. It seems to me that the same effect would occur if there were fewer available molecules of the required neurotransmitter.

Does over-stimulation of a neural pathway (through the use of a drug or other stimuli that up-regulates a given neurotransmitter) shorten the half-life of the neurotransmitters it uses?

Could a diet which is poor for necessary precursor nutrients cause a person's neurotransmitter concentrations to drop and reduce signaling along specific neural pathways?

Could lack of sleep or other physiological stressors have a similar effect?

I am not a neuroscientist so please correct (and forgive) me if I'm using any terms incorrectly or am flat-out wrong in any of my assumptions.


texts: What sections of the brain can be removed without causing instant death?

texts:
Years ago I've read about a young man you had lost a large section of his brain (frontal lobe) in an accident but surprisingly he survived it and continued his normal life. You may have read about that.

Now let's break down the question into 3 steps. Which parts of the brain can we remove without:

Affecting the normal life. This means, still being able to see, talk, understand, and more. Just like a normal person.
Losing conscious. This includes just being able to maintain conscious, being able to think and understand.
Dying. Which means only having the crucial organs such as heart and lungs running.

UPDATE

I'm neither looking for a list of every part of brain's million sections, nor it's possible to cover them all in a single answer. I'm merely looking for a list of widely-known largely-scaled sectioned, such as the below image.

Image credits goes to Mid Brain Power.


texts: Are there dichotomous keys for identifying medical conditions?

texts:
I know dichotomous keys are often used to identify flora and fauna.

I was wondering if they are also used in medicine for identifying diseases -- are they? If not, why not?


texts: I found this beetle in my yard. Wondering what type it is.


texts: Why is binding energy the difference between ∆G catalyzed and ∆G uncatalyzed?

texts:
I think the title explains it pretty well -- I'm confused on what 1) exactly binding energy is 2) and why it's the difference. Like in this diagram:

my teacher sort of said it was the energy the enzyme uses to make interactions to the substrate, but that doesn't really click for me.


texts:
Suppose the two parents of a child have blood groups A+ve and O+ve, and the child has O-ve type. For blood group, there are two alleles. Since the child has O, the father must have one 'A' allele and one 'O' allele.

Does such a reasoning hold for the Rhesus factor too? Should I interpret that both the parents have one + allele and one - allele?


texts: Looking for a cancer drug target database to guide sequencing of patient tumor DNA

texts:
I have a question I would like to pose to the community. I have recently received access to a bench-top ion torrent DNA sequencer. Our idea is to use this machine to sequence the DNA from patient’s tumors in order to guide treatment options. My job is to identify a list of all currently used anti-neoplastic drugs along with their known targets (i.e., specific genes and mutations) and accession numbers. I would like to put these data in a table in which each row corresponds to a different drug.

For example, a row in the table might read (column names are indicated in brackets): [disease] breast cancer, [drug] trastuzumab, [drug target] HER2/neu receptor, [gene] ERBB2, [location] chr17:37844393-37884915, [mutation type] amplification, [accession number] ENSG00000141736. The pathologists would then be able to use this database in order to select appropriate genes for sequencing whenever they receive a tumor specimen. If the patient’s tumor had an amplified ERBB2 gene, they could be given trastuzumab.

Currently our study is in pre-planning stages (i.e., we won’t actually be testing this on patients any time soon). I would appreciate it if anyone could give me on advice on how to go about creating such a database. I am aware of online databases including COSMIC, Sanger's Cancer Gene Census, and the Potential Drug Target Database (PDTD), but they don’t have everything that I’m looking for. I am familiar with R and could use it to combine data from multiple sources if necessary. If anyone else has comments or suggestions for further reading that would also be appreciated. Thanks!

Note: This question has also been posed on a Research Gate forum: http://www.researchgate.net/topic/Cancer_Biology/post/Looking_for_a_cancer_drug_target_database_to_guide_sequencing_of_patient_tumor_DNA


texts: What is the inlet/outlet speed of air going in/out of our mouth during inhalation/exhalation

texts:
During inhalation, your alveoli expand, creating a pressure difference between the atmosphereic pressure and our lung sacks and therefore air will flow into the repspiratory airways.

I am trying to find what the (I guess average) speed of this flow is, and therefore estimate the pressure difference. I have spent some time online trying to find this, but I have not got a definite number yet. It should be an order of magnitude of 1 m/s ?


texts: What is the name of this yellow / orange fungus?

texts:
I've seen this in October 2016 on Corsica (Island of France):

I would guess each one is about 5cm - 15cm in diameter. Obviously, they come in small groups.


texts: Why is menstruation in wild animals not a disadvantage to organismal survival?

texts:
When I watch wilderness specials for more than a few minutes, I notice a familiar pattern: predators are depicted as being alerted by the scent of blood. Wounded animals seem to make the best prey and predators seem to have a heightened awareness for the smell of blood.

It would seem that it would then be a disadvantage to evolutionary survival for female organisms to menstruate. How do females of a species not attract predators to the signal of menstrual blood?

Do female organisms in the wild actually menstruate? If so, is there a difference in the composition of menses that does not alert predators? How would this not at the very least give predators an idea of the general vicinity of the female?

If wild animals excrete their menses, do they have ways in which they are able to mask the evidence of its release or are they somehow internalizing the tissue so that they are not released?

If female organisms in the wild do menstruate, then why is this not a survival disadvantage?


texts: What do red ants secrete while marching in a line, one after the other?

texts:
Red ants often move in a group, and seem to follow a trail one after the other.

Once, I rubbed a part of the path along which they were moving and surprisingly found that the successive ants roaming around the rubbed region became confused as to where to go. It seems that the preceding ants secrete some kind of chemical (hormones, excretory wastes or body secretions) which guide the other ants to follow it. What is this secretion?


texts: Difference of coverage between amplicons

texts:
I have 2 fastq files and I generated BAM file (indexed and sorted) of some reads. I aligned them to a reference genome (hg19).

I am working with different primers.

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

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

Therefore I have different amplicons. How can I plot the coverage of these different amplicons. And what could explain big difference between them?

Thank you very much for your help.


texts: What kind of Brazilian Arthropoda is this?

texts:
It looks like a Diplopoda, but I've never seen anything like that. A friend took those pictures in the Brazilian Cerrado (Goiás state, Brazil) these days (October, start of rainfall in Spring). It was inside a country house, she already found it dead.

She said it has about 3 cm (~1.2") long. We can see it's not so small as a Symphyla or Pauropoda. Looks like it has 12 pairs of legs.


texts: Can assimilated energy be simply lost from a trophic level?

texts:
I was reading Environmental Studies By B. S. Chauhan and there a diagram of a model of transfer of energy.

NU = Not used energy has been shown, energy that was neither stored or exported to the next level.

I wonder what physiological process causes this loss of energy at all trophic levels?


texts: What are the functions of disulphide bonds?

texts: What are the functions of disulphide bonds between amino acids in proteins or peptides?


texts: Is there a hypothesis that attempts to explain patterns of species richness along all three energy-related environmental gradients?

texts:
My question is related to one of the oldest question in ecology: "What determines global patterns of species richness?". However, I want to focus on one particular part of this question, which has been bothering me for a long time.

Background information

One of the most widely recognized ecological patters on Earth, which is found at most scales and in most biological taxa, is the latitudinal diversity gradient (LDG) -- there are more species in the tropics than in the temperate regions, and the further away you move from the tropics, the fewer species you encounter. Furthermore, such pattern exists not only along the latitudinal gradient, but species richness also covaries with altitude in terrestrial environments and depth in marine environments, showing the same diversity gradient!

It seems to be fair to suggest that energy should somehow underline all these diversity gradients and create some sort of universal mechanism that would ultimately affect all species richness patterns on Earth. Unfortunately, there is no consensus on questions as grand as this one, but I'm looking for hypothesis that would specifically attempt to explain all three gradients together.

Question

Is there a hypothesis that attempts to explain patterns of species richness along all three energy-related environmental gradients together: latitude, altitude and depth? If there is, what it's weakness? If there's no such hypothesis, do we have reasons to believe that such a broad link across the three gradients can exist?

Please note how I'm trying to emphasize that I don't want you to list all the hypotheses that describe LDG only, but rather the three gradients together.


texts:
Location: Lansdowne, Uttarakhand, India

Date: 27 May 2017

Time: 5.33 pm

The insect was found walking upwards on a plastic table. It was about 3-4cm long, as far as I remember; its been a long time since I encountered it.
Spotted near a small shack in the Terai forests.


texts: Why does hair turn grey or white, and why does it happen later for some?

texts: The question is pretty simple: what is happening molecularly when hair turns grey or white? I would imagine that it is due to the lack of a particular compound. I'm also interested in why some people's onset of grey hair happens much later than others.


texts: Why a cell contains all DNA when it only needs a few genes?

texts: Is that what they called junk? Why does a simple cell have the DNA code for everything else when it just needs a few codes to function? Wouldn't that be a wasteful?


texts: Walk me through microsatellite markers and PCR

texts:
Three polymorph microsatellite markers are used to try and narrow down the location of a disease locus, with the use of PCR with 2
  flanks on each side of the actual polymorphic area. The PCR product is
  then put on gel.

I need help understanding exactly what is going on here. I understand polymorph as "two or more phenotypes in the same population" as by wikipedia. I don't understand what they mean here.

How is the PCR different with 2 flanks from a normal PCR?

I do understand how the gel works.


texts: Can yeast in a primary fermentation of wine be used as a source of yeast for new fermentation?

texts:
So if I were to pitch bread yeast, and get to primary fermentation, which as I understand it, is the point at which regular cellular respiration can no longer continue due to a lack of oxygen , which is needed for the electron transport chain. Therefore the yeast switch to fermentation, which produces my desired product, ethanol.

But as I understand it, at this state the yeast are no longer reproducing and are in a survival mode.

Therefore if I were to cut a 2$L$ bottle of my primary ferment in half, and then add more sugar and water to the now separate 1$L$ bottles, and oxygen (if possible), up to 2$L$, would I be able to have the same amount of ethanol produced/would fermentation even occur?

I feel there would be diminishing returns even if it was possible, since yeast can only reproduce asexually so many times, which happens during stressful times, which this process might induce?


texts:
The more general question would be whether or not one can scale an animal to some other size and preserve its properties. The method of scaling is by volume, scaling all dimensions by the same factor. The mass is scaled so that the mass/body ratio is constant.

Some factors I thought about:

How does muscle strength scale with muscle size?
Could the joints support the new mass?
If ducks rely on aerodynamics/wind to fly, how does the size change influence those factors?


texts:
Say I have one dsDNA that undergoes normal PCR (where amplification is exponential).  If there is a mistake, say a G is swapped for an A during the 2nd round of replication, what percentage of the final DNA will have the mistake if there are 12 more rounds?

I was talking to my teacher about this today.  I say 33%, my teacher said 12.5%.


texts: Eye Optics/Emmert's law: Where to place scaled copies of an object so they have identical images on the retina?

texts:
I read that the center of projection of the human eye is the entrance pupil. So given a light ray which intersects the objects position and the center of the aperture stop, all copies of said object when placed along that line should cover the exact same position/area on the retina (assuming they are scaled according to their distance).
However, doesn't this ignore the effect of accomodation of the human eye: If the original object is quite near, but a scaled copy along the ray is quite distant, the focal length of the lens is changed and thus a different position and area of the retina is covered.
I tried to visualize this by using the ray simulator at https://ricktu288.github.io/ray-optics/simulator/:

Image A:
Lens focussed on distance of Object A which is projected onto A' on the retina. Object copies B and C are placed at fixed distance either along a ray via the aperture stop (B) or via the center of the lens (C).

Image B:
Lens is focussed on distance of Object B/C which are projected onto B* and C* on the retina. Both are in focus (difficult to see in the picture), but B* is further away from A' than C*. Object B would appear larger than Object C.

So I guess this boils down to the question:
Given the position P of an object A and a lens system, what is the point Q which creates a ray PQ so that all scaled copies of A (A', A'', ...) at different distances along that PQ ray appear at the same position and area on the image created via the lens system.
Is there such a point Q? Is it the center of the lens (i.e. is C* == A') or one of its nodal points?
I am thankful for any pointer to help me understand this!


texts: Statistical Coupling Analysis (SCA) to identify coevolved residues: use of ICA

texts:
We've begun to try out the SCA Matlab toolbox (latest version) downloaded from Dr. Rama Ranganathan's website, and, following the included tutorials, would like to apply it to our protein family. The SCA calculation involves determining independent components (IC) of positional covariation by applying the "Infomax" algorithm to a few top eigenmodes (that have been obtained from the positional correlation matrix). Here, we observed that the output (IC vector weights) seems to depend on the no. of top eigenmodes chosen as input (i.e. on choice of the parameter kmax). If this is indeed the case, then is there some "working rule" to optimally choose kmax (say, based on the number of significant eigenmodes turning up)? Since this isn't made very clear in the tutorials (at least to me), I thought of trying my luck here.

Would really appreciate some guidance/pointers from SCA users. Thanks a lot!


texts: Neanderthal and modern human population sizes

texts:
Are there any estimates of both the modern human and Neanderthal population sizes over the last, say, 100 k years? Since "purebread" Neanderthals are extinct, their population has to hit zero; that happened sometime around 30 k years ago. We have good estimates of both the Neanderthal (zero) and modern human (millions, billions) population sizes in the recent past -- what I'm wondering is what the numbers were (roughly) when modern humans and Neanderthals came into contact. How many people were there in each group? How many interbred? Is there any reliable way to estimate those numbers given what we know today? If not, would it be possible, if we sequenced the genomes of a large number of Neanderthal fossils, to get a sense of how much variation there was in their gene pool, and use that to estimate the size of their population? Could we also look at how much of that variation survives today in the homo sapiens gene pool?

In Why Did 6 Great Ape Species Survive But Only 1 Hominid Species? the poster states that "following the eruption of the Toba volcano 70,000 years ago, there were between 1,000 and 10,000 mating pairs of Homo sapiens left." Was the Neanderthal population of a similar order at that time? Was it ever larger than the modern human population? We'll never know the exact numbers -- and the exact numbers don't really matter. I'm interested in orders of magnitude. When homo sapiens and Neanderthals interbred, did sapiens already outnumber them, or were the populations roughly equal? Were the number of Neanderthal - sapiens crosses tiny relative to both populations, or were they perhaps large relative to the smaller of the two populations?

A related question:  Of the Neanderthals living, say, 100 k years ago, what fraction have descendants who are alive today?  Is that a question we can answer either now or in the near future, after sequencing more Neanderthal genomes? According to http://www.nature.com/scitable/knowledge/library/what-happened-to-the-neanderthals-68245020

  recent research on Neanderthal nuclear DNA has found evidence for
  limited admixture: a small portion (up to ~4%) of the genomes of
  non-Africans so far examined may derive from Neanderthals, suggesting
  that interbreeding probably occurred in the Near East during the
  earliest dispersal of modern humans out of Africa, but prior to their
  arrival in Europe (Green et al. 2010). Demographic modeling of
  admixture combined with territorial expansion, however, indicates that
  this level of introgression would be produced under very low (<2%)
  interbreeding rates and strong barriers to reproduction between
  Neanderthals and modern humans, arguing against assimilation (Currat &
  Excoffier 2011). Pending the completion of the Neanderthal genome and
  ancient DNA analyses of early modern Europeans dating to the Upper
  Paleolithic, and following the recent discovery of a third possibly
  coexisting species from Denisova cave (Krause et al. 2010), it is
  premature to conclude that the currently observed level of admixture
  constitutes assimilation.

That would suggest that the fraction of Neanderthals with living descendants is very small -- most Neanderthal lineages died out. What evidence would it take to conclude the reverse -- to conclude that the Neanderthal population was very small, and was largely assimilated?


texts: Inhibitory effect of GABA through GABA(A) receptors

texts:
Over at Wikipedia, the following is written in the article about GABA(A) receptors:

"Upon activation, the GABA(A) receptor selectively conducts Cl− through its pore. Cl- will flow out of the cell if the internal voltage is less than resting potential and Cl- will flow in if it is more than resting potential. This causes an inhibitory effect on neurotransmission by diminishing the chance of a successful action potential occurring." (https://en.wikipedia.org/wiki/GABAA_receptor, Accessed: 22 May 2018)

Based on my understanding, if an action potential is to be inhibited, the internal voltage of the neuron needs to be decreased further away from the voltage at which the neuron's voltage-gated sodium channels open up.
With this in mind, I take issue with the statement Cl- will flow out of the cell if the internal voltage is less than resting potential.... If the internal voltage is less than the resting potential, and the Cl- flows out from the cell, then the internal voltage will increase, hence coming closer to the action potential.
This would increase the probability of reaching an action potential, not decrease it, wouldn't it?
My Question: Does Wikipedia have it wrong, or is there something I haven't understood?


texts: Decreasing the alcohol proof and faster in hangover, why?

texts:
My russian friend says that the USSR agents used/use the trick that they offered the victim first vodka and then last wine.

I have noted that this puts you faster to hangover: decreasing the alcohol proof.
Some people lose their motor function immediately and some their memory only.

Why does a decrease in the alcohol proof cause you a) faster intoxication and b) faster hangover?

Probably the change in the concentration of alcohol inside cells of brain tissue affects some parts of your brain like the cerebellum. I would like to have an explanation in Biochemistry.

Is there any truth in my friend's argument?


texts:
How are new staining protocols designed for microscopy? Is it manual work or does it rely on computer simulations?

Say for example I thought the H&E staining does not bring enough contrast. How would I go about producing The Superb H&E Staining Protocol (not necessarily using just hemalum and eosin Y)?

Looking this from a mathematical point of view, the staining is some operator O applied on image I to produce enhanced image E. While clearly the operator O depends on the particular type of specimen, what I want to see, etc., there are surely some general principles guiding the search for finding an appropriate operator O? What are they?

Since the question is on hold, maybe I can try to put it even more clearly. How was the H&E staining invented? What was the process for its invention? I don't see why it would be unclear what I am asking. Dear biologists please take a more interdisciplinary approach.. If the question really is not answerable as such, please explain why. There's probably an answer in that.


texts: Why is selection less effective in small populations than in larger?

texts: I can understand that the genetic drift has a higher impact on smaller populations, but what does it mean for the selection to be less effective in small populations than higher?


texts: I found that in a monastery garden in Czech Republic this winter. I tried to search it on the internet but unfortunately I didn't find it.


texts: Brownian motion : Understanding the output of mvBM function.?

texts:
To fit the brownian motion for independent evolution of traits i used below code:

rownames(carni)<-gsub("_",".",rownames(carni))  #Renaming to match the tip of tree
#Independent Evolution
brown_indepen <- mvBM(carni_tree,carni,param=list(constraint="diagonal"))

mvBM is the function from mvMORPH package. It seems by giving constraint="diagonal" would fit the model for traits to be evolved independently. I would like to know the idea behind it. Also, i got the below output after running the code. I would also like to know what below output means.

LogLikelihood:   -589.2373
AIC:     1186.475
AICc:    1186.771
4 parameters

Estimated rate matrix
______________________
      size    range
size  73.70335  0.00000
range  0.00000 13.54524

Estimated root state
______________________
       size    range
theta: 38.43947 13.78439

Size and range were the two traits.


texts: Are Gram negative bacteria classified as such because of their negative membrane potential?

texts:
Does the membrane potential usually quoted for Gram negative bacteria (e.g., E. coli) refer to the potential across both membranes? - If yes, then does the potential fall more over the inner or outer membrane? Are there any studies that estimate/measure the relative fraction for each membrane?

I assume that the measurements of potential are usually carried out by inserting an electrode inside the cell and measuring the difference with the outside, this would make the answer to the first question yes.


texts: Well can a bacterium be used as a vector?I have learnt that Agrobacterium tumifacian can be used to deliver a gene of interest in plant cells but on a book in a multiple choice question it says that only plasmid and bacteriophage can be used and not the bacteria to deliver a gene of interest to a host cell.


texts: Exporting RNA in extracellular vesicles (exosomes)?

texts:
I'm interested in how much is know about the process by which RNA is secreted from cells into extracellular vesicles.

Where is a good place to start reading about this?

How much is known about this pathway?

Can the pathway be engineered?


texts: If you are at some quiet place, you will hear some mild noise when you tighten your jaw. Why is this? Is this sound produced by face/jaw muscle?


texts:
Wikipedia has two images, of a eukaryotic gene and of a prokaryotic gene.
They show the difference that the prokaryotic gene also has an operator while the eukaryotic gene does not. Both also have enhancers and silencers separately. I thought enhancers and silencers were types of operators. Is this wrong?


texts: Pharmacologically, can tricyclic antidepressants have a side-effect profile similar to neuroleptics?

texts:
Torticollis (wryneck, cervical dystonia) is a neurologic movement disorder causing involuntary muscle spasms in the neck. Often, neuroleptics can cause such a side effect.  I'm wondering if this condition could also be part of the side-effect profile of  tricyclic antidepressants, like amitriptyline.

Some potential indications:

Often the basal ganglia are associated with neurological conditions such as movement disorders. -> Do amitriptylines effect the basal ganglia?
Dressler and Benecke claim that "Of all patients treated with neuroleptics approximately 2 to 3% develop acute dystonic reactions within days of therapy initiation .When highly potent neuroleptics are used this rate may increase to over 50 %.Young men are at a particularly high risk. Cranial, pharyngeal, cervical and axial muscles are most commonly affected causing oculogyric crisis, grimacing, fixation of the jaw, retrocollis, torticollis or even opisthotonic posturing." -> Do tricyclic antidepressants operate similar to neuroleptics?
Geyer and Bressman claim that dystonia can be caused by certain drugs: "In addition to inherited forms of secondary dystonia (dystonia-plus syndromes and neurodegenerative diseases), a variety of acquired insults can cause secondary dystonia in previously unaffected individuals. Many cases are iatrogenic, resulting from drugs that block dopamine receptors; antipsychotic and antiemetic drugs are the most common culprits." -> even though amitriptyline doesn't seem to block dopamine, maybe there is some kind of connection?
Tricyclic antidepressants sometimes seem to be used to treat torticollis, so is the reverse effect of causing the condition also thinkable?


texts: How does SARS-CoV-2 spread from cell to cell in the lung?

texts:
This virus exits the cell using exocytosis after assembling golgi vesicles which contain the virus by fusing with the cell membrane.

In the case of infected pneumocytes, I imagine that the virus could then exit into the alveolus and infect other pneumocytes using again the interaction of the S protein with ACE2 or it could exit into the blood and spread to other pneumocytes in a 'miliary' fashion like TB.
Is either or both the main mechanism of spread in the lung?
Does lymphatic spread play any role?


texts:
We recently found a nest in the back garden and a little bird inside. Can you help us identify it? The nest is quite small like the bird so we are wondering whether this is the parent or a baby chick. Is there anything we can do to help it or are we better off leaving it alone?

Update: I'm from the UK, currently in Oxfordshire to be more precise.


texts: I want to know what gene or protein makes bacteria psychrotrophic, as opposed to regular bacteria that prefers warmer conditions. If you don’t know exactly, and you have suggestions as to where I can find the name of the gene, that would be great. I would also need the gene to be accessible so if anyone knows anything, please let me know. Thank you!


texts: In which month should I map maritime vegetation?

texts:
I'm studying habitat use by Brent Goose in the UK, a species that feeds on maritime vegetation. It's main food types are Zostera sp., Ruppia sp., Ulva / Enteromorpha sp. and Puccinellia sp. I plan to map these vegetation types on an inter-tidal mudflat in North-east England during the summer.

I want to choose a month to map these vegetation types that will allow the most accurate mapping of their distribution of vegetation across the mudflat. I think there are two considerations 1. the month they easiest to identify 2. the month they are most visible.

Which month should I choose?


texts:
Microcytosis, i.e. decrease in the size of RBCs occurs:
– In iron deficiency anaemia,
– During prolonged forced breathing and
– When osmotic pressure of the blood is increased.

I am unable to understand how forced breathing results in microcytosis.

My attempt: I think prolonged forced breathing results in low CO2 concentration in blood which would lead to low H+ ion concentration , but this would lead to hypo-osmic plasma, which would certainly produce macrocytosis.

Source:Textbook of physiology


texts: Why is there a low rate of kidney disease related deaths in the Baltic countries?

texts:
A noticeable feature of the map of kidney disease related deaths is that the Baltic countries, Norway, Finland, Estonia, Latvia, Lithuania, etc have lower rates:

Why is this?


texts: Can we force a species to evolve through a mixture of natural and artificial selection in a closed environment?


texts: To which distinctions does the term "hymenoptera" refer?

texts:
Hymenoptera is an order of insects that includes bees, ants, and wasps. A quick search gives the following etymological analysis of the term hymenoptera.

  hymen (membrane) + pteron (wing)

Does the term hymenoptera have a firm basis in biology and physiology? In other words, what is different about membranes or wings (or membranous wings) in species of hymenoptera as opposed to species of other orders of insects?


texts:
After reading about how recombinant insulin is produced, the following question occured to me. Does the current level of technology allow any enzyme to be produced in a similar way?

As I see, producing amino acid sequences is not an issue. A possible difficulty I can think of is modifying the amino acid chains. In the case of insulin the problem has been solved. Are there some generally applicable solutions available to this problem, or do they have to be researched on a case-by-case basis?

Are there any other limitations to producing enzymes?

EDIT: As pointed out by P. Jay, the question might seem to suggests that insulin is an enzyme which it is not.


texts: Potential to destroy viruses using prions?

texts: Could a prion be used to sufficiently deform a viral protein in order to make the virus it is a part of incapable of reproducing? For example, take the common cold's VP1 protein and turn it into a prion, then inject that prion into someone with a cold. Would this prion ever come into contact with the virus? Would it actually deform the virus? Can we make prions?


texts:
We used pH6.8 in stacking and pH8.8 in resolving gel. In the class, the professor explained that the glycine change is like:

glycine+ <-------> +glycine- <------> glycine-

it is said that most of the form will be +glycine- and glycine-. Why? And why does it change the charge when it runs from the stacking gel to resolving gel? What is the role of glycine in the running buffer for SDS-polyacrylamide gel electrophoresis?


texts: What is the difference between alarmones and riboswitches

texts:
An Alarmone is an intracellular signal molecule that is produced due to harsh environmental factors. They regulate the gene expression at transcription level. A riboswitch is a regulatory segment of a messenger RNA molecule that binds a small molecule, resulting in a change in production of the proteins encoded by the mRNA, it works as a way to sense eviromental changes.

I've been reading some papers ("ZTP 5-Amino 4-lmidazole Carboxamide Riboside
S-Triphosphate): A Proposed Alarmone for 1O-Formyl-Tetrahydrofolate  Deficiency" , Bochner 1982; "An Ancient Riboswitch Class in Bacteria Regulates Purine Biosynthesis and One-Carbon Metabolism" Kim 2015) which study how ZTP can bring changes upon 10f-THF deficiency. Bochner (1982) through several experiments proposes ZTP as an alarmone for 10f-THF; some assumptions of Bochner might not have been entirely correct and a later paper fails to replicate some experiments. Later Kim (2015) propose ZTP as a riboswitch.

I'm not fully aware of the differences between the concept of "alarmone" and "riboswitch". Seems to me that both Bochner and Kim propose virtually the same thesis.


texts: What is the connectivity between on-center & off-center bipolar cells?

texts:
Do rod-photoreceptors only form synapses with on-center bipolar cells (and on-center ganglion cells in the next step)? If so, why is that?
Why do rod-cells only connect to on-center cells, while the cones connect to both on- and off?
Am I correct in saying that what happens in the bipolar cell as a response to light stimulus on a photoreceptor depends on i) Wether it is an on-center or off-center bipolar cell - and of course where the light stimuli is focused on the bipolar cell (periphery or center), or ii) What kind of receptors the on-center and off-center bipolar cells have? This is the part where I get really confused, because I read somewhere that what kind of receptors On/Off-center bipolar cell have, is not something set in stone? So saying that On-center bipolar cells have AMPA receptors and will, as a result of that, react in a specific way to less Glutamat release would be wrong?
How does this release of neurotransmitter works together with central / periphery stimuli. Let me try and use an example, You have an on-center bipolar cell. What will happen if light is focused on the center of this cell's receptive field? And what will happen if it is focused on the periphery? Let's just say that the light hitting the center of this cell's receptive field causes it to be depolarized. But is it really the light hitting the center which causes this effect, or is it the decrease in Glutamate release from the photoreceptor that causes this effect? If the latter, then what does it really matter if the light hits the periphery or the center of the bipolar cell's receptive field? The photoreceptor is hyperpolarized by light either way and less Glutamate will be released no matter what.
Also, in order for this to make sense, the light that enters the eye is absorbed by the photoreceptors pigmentmolecules, but some of the light also has to hit the receptive field of the bipolar cell in order to decide which signal to be transmitted? So not all of the light is absorbed by the photoreceptors then?
If the light hits the periphery of an On-center bipolar cell, you will have an inhibitory effect, is that right? And the other way around, if the light hits the center of the cells receptive field, you will get an excitatory effect? But I am curious as to how this also has to do with the kind of receptor that the on-center bipolar cell has (AMPA or MGluR6).


texts: A friend of mine saw this monstrosity in Taiwan. The photo isn't very clear but you can't blame her considering it was the size of her face. Wanted to know what species it is so I know where they spawn and to stay away from those areas.


texts: How can one relate in vitro studies of caffeine (dose expressed as concentration) to dietary intake of caffeine (dose in mass)?

texts:
Having difficulty making the data in the below charts to apply to daily life. What is the right interpretation and implementation? How are the “in vitro” results of the below charts relevant to levels that cells would experience "in vivo" after the consumption of caffeinated beverages?

Link to the medical research article which the two above charts were taken from


texts:
Sorry for such a question,if it is too naive.

Is there any definition of complexity about gene and protein according their function?If so,what is the relation between them?


texts: Is there a timeline for the frequency of evolution of any species?

texts:
Evolution is traditionally spoken of as an inherited change over generations.

Does evolution happen one change at a time - or are there multiple changes occurring between two successive generations? Is there a known timeline for the frequency of such changes in any species?

Something like ...

20 Million years ago - Species X showed A, B, C.. Z characteristics

19 Million years ago - Species X following characteristics changed A'

17 Million years ago - Species X following characteristics changed B', C', Q', M'

16 Million years ago - Species X following characteristics changed A''


texts: What is the general mechanism behind perfusion PET imaging

texts: I understand how tracer kinetics can be used to determine binding potential but how it can be used to detect perfusion eludes me.


texts: Can the human eye axial length decrease?

texts:
I just have a quick question regarding the axial length of the eyeball.
I understand that the axial length of the eyeball grows up until your around 20 years of age which is why hypermetropia decreases with age but myopia doesn't. My question is, can the axial length of the eyeball decrease and does it naturally?
I know that certain conditions can cause the axial length to reduce such as very low pressure or disease but my question is regarding a normal healthy eye. I have found 2 studies which I will link below. In one of the articles it says that with current research we KNOW that the axial length decreases with age this same point was also in a different study based on the idea of a an emmetropizing mechanism for the adult eye but many people have criticised this study and due to this apparently the studies findings should be taken with a grain of salt but if this is the case why is it that many articles do say that the axial length reduces with age is there another study that shows this?
The other study that I will link below basically used lenses to create hyperopic and myopic defocus in participants and they measured the axial length of the eyeball after exposure to the blur. They found that the axial length did decrease in the case of myopic defocus and increased in the case of hyperopic defocus in order to create a clearer image by focusing the image on the retina but if this article provides definitive proof that the eye does in fact change its axial length then why is that people still say it doesn't happen?
Also do we know which mechanisms allow the eye to determine whether it is myopic defocus or hyperopic defocus that is presented to the retina?
Lastly, if the eye's axial length is able to reduce wouldn't myopia have a cure or at least a method to reduce it based on the reduction of the axial length of the eyeball?
Thank you for taking the time to read my question and I look forward to your answers!
https://www.karger.com/Article/Fulltext/317072
https://www.quora.com/How-can-the-axial-length-of-an-eye-decrease-as-they-say-that-it-does-with-ageing
https://iovs.arvojournals.org/article.aspx?articleid=2126435


texts: What is the effect of pasteurization and ultra-pasteurization on proteins, enzymes, and nutrients found in milk and other dairy products?


texts: Why didn't humans evolve to reproduce identical twins all the time?

texts: According to the selfish gene theory, it seems like because identical twins sometimes get produced, a mutation to a gene that says, "if you have an identical twin, be fully altruistic towards them" would get selected for when ever it happens to arise in an identical twin. After humans evolve to be fully altruistic towards identical twins, wouldn't a mutation to a gene that makes a woman more likely to produce identical twins also be selected for because if it happens to appear in a a child who has a non-identical sibling, that gene might be discontinued from reproduction by the partial selfishness of the sibling but if it appears in an identical twin, the other identical twin will preserve that gene with their altruism.


texts:
Life on earth started an estimated 3.8 billion years ago, very soon (in geological time) after the earth’s surface cooled to become solid and the first oceans formed. Nowadays, we believe that all living things can trace their ancestors back through a multi-branched tree of life, to this first living thing.

How do we square this rapid appearance of life, with the fact that it only seems to have developed once? In other words, we didn’t have life starting up in 10 different places on earth, giving rise to 10 different trees of life, why did we see only one?

In a variation on Richard Dawkins’ Selfish Gene, is it possible to think about a Selfish Tree?

Once the first tree of life arrived, it set about changing the atmosphere and environment generally, multiplying the number and range of species to fill every available niche (eg cold, hot, land, river, ocean, acid, alkali, large, small) in order to leave no space or circumstance for a second tree of life to spring into being.


texts: Is it possible to use virus for genetic modification of embryos during the fetus stage

texts:
I know this probably sounds rather hypothetical and not very feasible but I would very like an answer telling why it is possible or not possible and why.

With the advancement of crispr and other dna technologies, I have been wondering whether it is possible for us to use a virus, which would easily pass through the gaps of the placenta and infect the developing fetus to alter its genomic materials for the creation of designer babies. Since Zika can alter the genome of a baby to cause deformities, is something opposite also possible, like using a similar virus to develop favourable genes in a fetus.

Also, what are the chances of the virus actually purposely acting under orders of genetic engineering to intentionally deliver the genes through transduction?

Putting all ethical and moral issues aside is such a principle feasible and if no, why not?


texts: How did the Chromosome #2 Fusion propagate?

texts:
There is strong evidence that chromosome 2 in humans is a fusion of two chromosomes of a common ancestor of chimps and humans as explained at wikipedia here

Was it necessary for the common ancestor with fused chromosome 2 to mate with another creature whose 2 chromosomes fused in a similar manner?

If yes, what would their offspring look like? would they also need to mate within themselves or could they mate with the chimp population?

if possible, also, how in the world could a genetic disadvantage take over the population? doesn't this contradict natural selection?


texts: Reflexes & Pathologies including the Vagus Nerve

texts:
I only know the vasovagal reflex. I would really appreciate if someone could inform me about the other ones.

About the pathologies, I already know the effects of direct nerve damage. I am talking about more sparse and indirect ones, for example so far I found Roemheld syndrome, which is a gastrocardiac syndrome.

Actually, any subtle clinical presentation including the vagus nerve could be really helpful!


texts: Measuring a plant's electric activity any instructions where to place electrodes?

texts:
I would like to measure a plant's electric activity / voltage, I've looked online to find out where to place the electrodes and what type of electrodes to use but they seem to very wildly.  Any ideas?

At the moment

I plan on wiring one end of a needle to the stalk and one end to the soil.
The connections from the plant would go to a laptop mic input to record the signal then I would normalize the signal.
I would then process the signal in MATLAB/Octave using FFT.

Any thoughts or videos on connecting the electrodes to the plants or trees?

I did find this Development of Bio-Machine Based on the Plant Response to External Stimuli


texts: What happens in the synapse when cocaine administration occurs in the human brain

texts:
As far as i know when you accept cocaine in your blood some cocaine molecules reach some synapses in your brain and fill some Reuptake tunnels preventing the cell to simply "do not know that fired neurotransmitters have achieved their task" and doing so the cell fires neurotransmitters again becuase "it" simple do not know that "it" have achieved its task.
In this case cocaine molecules fill Reuptake tunnels in Dopamin Serotonin and Norepinephrine
orientated neurons.But since the firing occurs when an electrical signal occur how the neurotransmitters are fired again when such electrical signal does not exist?

If im mistaken in my physiology knowledge explained above please correct me!


texts: Why is beta- D fructofuranose two different structures when in free form and as part of sucrose?

texts:
This is the structure of fructose in free form:

The right moiety is the fructose as part of sucrose. The left one being glucose:

Both of the fructose are beta-D fructofuranose. But as it can be seen they both are clearly completely different structures. The anomeric hydroxyl group seems to be in an opposite position while the rest of the structure hasn't even changed shape.

Where am I getting this wrong. Thanks.


texts:
How do mutations and protein synthesis link to cancer?

I know that a mutation in DNA can cause the triplet code on the mRNA to change so different amini acids are made and a different order means a different protein is made but how does it link to cancer when cancer is caused by uncontrollable mitosis.

Thank You

This question is at GCSE level so freshman/sophomore level.


texts:
Can one assess muscle strength through imaging (e.g., MRI)? If so, though which type of imaging and how accurate is it?

On How does muscle size relate to strength?, I read this answer from  Moses (mirror):

  Strength training will increase the size and quantity of myofibrils, and subsequently increase the size of the respective muscle fibers; this process is called hypertrophy, and it results in larger and stronger muscles.

As a result, I assume that a medical imaging processing the physical strength of a muscle should assess both the size and quantity of myofibrils. That being said, it can be easier to assess the size as an approximation of strength, and if so, I wonder about 1) the quality of such an approximation 2) how to measure the size of a muscle that what cannot directly easily measured with a tape ( e.g., gluteus minimus or piriformis).

Direct measurement of muscle strength something isn't possible or advised, e.g. if the tendon is injured. Also, some muscles are difficult to isolate when testing. In the case of a tendon injury, assessing the muscle strength would be useful to find a good balance between muscle strengthening and tendon recovery.


texts:
I really wonder what this is:

I find it near pound in Czech Republic (Central Europe). It's 2 inches long, AP. half wide. It was quite fast.


texts: Can a fungus become resistant to a chemical such as Potassium Permanganate?

texts: A friend used potassium permanganate solution to treat tinea on the hands/feet but after some initial success, the tinea seems to be making a comeback. Could the fungus develop resistance to potassium permanganate?


texts: Why is elevated homocysteine considered a risk factor for angina?

texts: Elevated homocysteine levels are listed among risk factors for angina. How is homocysteine related to the heart? Or the coronary arteries? How do these relationships make it a risk factor for angina?


texts:
Why can't we take the fur of a fox without killing or skinning it just like the sheep , what's the biological or chemical structure or even the trait which is on a sheep's body that separates wool from its skin
Why can't we apply the bioclip technology on furry animals too ?


texts: Is it possible to biologically convert potential energy to chemical energy?

texts:
To lift an object x meters it is necessary to expend, at a minimum, an amount of energy corresponding to the increase in that objects potential energy associated with the increase in height. When putting the object down, returning it to the position it was moved from, its potential energy with respect to gravity returns to the original amount. However, this potential energy is not returned to the person who did the lifting. On the contrary, putting an object down gently requires additional energy to be expended to slow what would otherwise be a free fall.

Can any organism convert gravitational potential energy to chemical energy? Is it at all biologically feasible?


texts: What are these two insects (or at least one of them)?

texts:
I need to catch and identify insects for my biology project, but I cant identify those two bugs.

Can I get the genus and the species (or it can be just general name of what this type of bug is called?)

They were found in Chicago suburban area.


texts: Should the sum of RPKMs be constant over experiments

texts:
I have cufflinks data from 18 different RNA-seq experiments.

I've noticed that if the sum all the RPKM values for a particular experiment, are vastly different between experiments. How could this be? I was under the impression that RPKM was normalized by the total number of reads. If that is true then the sum of RPKM values for a single experiment should be the same?


texts: What is the basic structure of the nuclear lamina

texts:
What gives the nucleus
  its shape is a mesh of intermediate filaments called the nuclear
  lamina. It forms an interface between the chromosomes and the inside
  of the nuclear envelope. If these large protein fibres were to be
  temporarily separated into their component nuclear lamina, the nuclear
  envelope would pull away from the chromosomes and withdraw into the
  endoplasmic reticulum. Problem solved.

I am confused by the last sentence starting with "If these large proteins..." Could someone explain this in another way? I would appreciate any response. Thanks!


texts: Is it reasonable to assume that RNA polymerase would bind preferentially to the promoter of the long allele of the SERT gene?

texts:
I'm trying to come up with an idea for a school project (a hypothetical research study).

I'm looking at depression and the serotonin transporter gene, which is highly expressed in the human cerebellum. There are 2 common alleles of this gene, a "long" and "short" version. The difference is that the long version has 16 repeats of a certain sequence in the promoter, and the short has only 14 repeats. Though there have been some controversial findings, the short genotype has been linked to patients with depression, suicide, less serotonin uptake, and less localization of the serotonin transporter at the cell membrane (synapse).
My hypothesis is that RNA polymerase binds preferentially/more strongly to the long allele's promoter over the short allele's promoter in human cerebellum neurons.

This would explain higher levels of transcription of the serotonin transporter gene (though this hasn't actually been shown) and increased serotonin uptake (has been shown), resulting in lowered susceptibility to depression.
I was thinking I would do this using ChIP. I would get cerebellum tissue from deceased patients of each genotype (long/long, long/short, short/short) and compare bound RNA-pol in the different genotypes.

My two questions are:

Is this a reasonable hypothesis (does it make sense based on what I have described)?
Hypothetically, is it possible to do ChIP on dead brain tissue?


texts: Does current evidence support the use of resveratrol as an anti-ageing drug?

texts:
A while back there was a lot of noise about resveratrol, a naturally occurring phenol which was touted as a potential anti-aging drug due to its role in regulating the SIRT 1 gene. A number of studies suggested that it could extend the lifespans of model organisms such as D. melanogaster and C. elegans.

Has there been any follow up on this? Have there been any human trials?


texts:
My current understanding of co-transport is that, first, a substance is actively transported across a membrane, establishing a concentration gradient across said membrane. This same substance then diffuses down the established concentration gradient, effectively travelling back to where it began, but this time travelling via a transmembrane protein that transports another substance also, regardless of its concentration gradient. Thus, this second substance is transported to wherever it is necessary.

Would it not then make more sense for the latter substance to simply be actively transported to its destination, as opposed to involving another substance which has no net movement at the end of the process? What is the advantage of co-transport?


texts: What's the difference between morphospace expansion and packing?

texts:
I'm reading an article that talks about morphospace and niche expansion or packing.

  Differences in slope above and below zero indicate dominance of
  morphospace expansion versus morphospace packing, respectively.

What do the terms mean? What's the difference?

The way I understand it is that morphospace expansion is the change in morphology from the perspective of a population, but morphospace packing is, from the perspective of the ecosystem, the process where organisms are occupying the ecosystem space entirely so that no niche are available anymore. Is that correct?

The "packing" seems to refer to the density of the different "regions" of morphospace. Or said differently, you could "pack" different morphotypes in an environment. Is this a probable explanation?

I haven't found an answer looking at the history and definitions of niche.


texts: Can bacteria release free DNA into their environment?

texts:
Natural transformation AKA natural competence involves the uptake of DNA into a competent bacterium (for horizontal gene transfer or as a food source). My question is about where this extracellular DNA can come from. Typically this "free" DNA originates from lysed bacterial cells. Are there instances where DNA is released without lysis that other bacteria can uptake via natural transformation?

Note: I am not interested in bacterial conjugation because I'm specifically interested in extracellular DNA that can be internalised by competent bacteria.


texts: If I want to screen for mutant yeast (S. cerevisiae) colonies that have defects in mitotic chromosome condensation, can I screen for colonies arrested in Mid-M phase? Would that work?


texts: Does GC content determine codon bias or does codon bias determine GC content

texts:
I was wondering if someone knows the answer to this quenstion, because I can't find a clear answer, maybe there isn't a clear answer :).

question
Which of these two is right? or maybe both influence each other

GC% determines codon bias
codon bias determines GC%

Thankyou,


texts: What characteristic(s) of inverse agonists allow for inhibitory effects?

texts:
I know that inverse agonists have similar structure to its complement agonist; and, as a result, they have the ability to bind to the same receptor, causing an inhibition of the pathway considered.

My question is, if the agonist and inverse agonist have the same structure (and possibly/extremely likely the same energy levels, steric effects, etc.), how is it that the receptor molecule reacts differently?


texts: How do red blood cells survive without a nucleus?

texts:
I was reading this question

Why do mammalian red blood cells lack a nucleus?

According to my understanding, a nucleus is the cell's control center (like the brain). All the functions in the cell are carried out according to  the nucleus's command.

Then how can a red cell survive without a nucleus? Why does it still perform all the functions correctly without the nucleus?


texts:
By default, pymol seems to grab the number of cores on the system for rendering. How can I force it to only use one core?

Motivation:

I have a large collection time-series of of coordinate data from a computational protein folding experiment. I'd like batch render the generated pdb files into a movie in a programmatic way. Pymol however likes to eat up as many cores as it finds available. I'd like to retain some control of the computational burden (required for some computational cluster jobs). How can I force pymol to only use one (or n) core(s)?

Solution:

While the question was closed (as it was decided to not fit into biological criteria of the site) future visitors might find it useful to know the answer:

set max_threads, 1

The solution was found in a Biostars question.


texts: How can skull size difference alone explain behavioral differences using evolutionary theory?

texts:
I just started Robert Sapolsky lectures series on Youtube on Human behavior biology, and on the second lecture, at this point, he is explaining how evolutionary biology can be used to predict lots of animal behaviors just through the differences on the skull size of adult males and females.

He considers two groups of primates, one in which the skull of the adult male is quite bigger than the female and the other where they are about the same size. He then asks the student: "which group would display higher male aggression?" I am lost at this point. How can the size difference alone be used to answer that question? The students answer the question: "the first group (in which the males are bigger)", and the reason provided is that their body is built for it. Why and how?

Following up, the next question is: which of the species has more variability among males in reproductive success? The answer provided: "obviously, it is the first one because the males are aggressive for a reason, and that is they are competing for reproductive access." Couldn't it be that the second group had a biological variation in sperm productivity, that greatly outmatched the fight for reproductive access of the first group? I mean, how can it be this easy to conclude such a complicated process? Shouldn't you carefully consider millions of other things before concluding that one group will have higher reproductive variation simply because of differences in the size of the skulls?

Thanks!


texts:
I have encountered the term genomic adaptation in some literature (for example Sikkink et al. 2017). I am struggling to parse the term, and I have not been able to find a definition for it.

Is genomic/genome adaptation the changes accrued by the genome as a result of evolution?

Or does it refer to some sort of active response by the genome to a particular environment upon introduction (of the organism) to said environment?


texts:
I have killed maybe 5 of these little bastards as I have a 3 year old and dont want her bit.  Should be able to zoom in quite a bit. Just hold CTRL and hit the plus symbol.

Whitish top
brown legs
stripped maybe yellow or white on the butt with black
Seen them all times of the day.

Kinda reminds me of the ant-mimic spider but I am unsure, need assistance.

And a close up:


texts: I understand that the vertical tails of fish and the horizontal flukes of cetaceans evolved due to the spinal movements of their ancestors but I was just wondering if there has been any investigation into which was the most efficient for swimming (speed, required effort etc...)?


texts: Why do soap molecules not break down your skin cells when you wash your hands?

texts:
Soap molecules are similar in structure to phospholipids and interact with the cell membrane.  They can clearly cause damage to the cell membrane.

If this is the case, why then, does soap not break down your skin every time you use it?  The skin cells, keratinocytes still have a membrane, so wouldn't soap attack our skin in the same way it does to plant cells and cause deterioration?


texts: What is the smallest scale at which blood vessels, nerves and other structures are deterministic?

texts: Super simple question, but I can't find the answer on the Internet (and I'm in a foreign country so the library is not English.) As the title says, what is the smallest scale at which blood vessels, nerves, lymphatic vessels, bronchi, renal structures, etc.. are deterministic (same for most of the population)? For example, I'd imagine capillaries are pretty much random, while (most?) people have an aorta, so where does the pattern break? Is there a scale at which an animal's body is probably similar to their siblings but dissimilar to a complete stranger? Or is it just a statistical distribution thing (the smaller you go the more standard deviation you get)?


texts: In adverse effects of Heparin, why is bleeding from deeper organs more common?

texts: The reason given in my book is that it i because it interferes with the secondary hemostasis..but i did not understand how that implies that bleeding from deeper organs is more common..


texts: How many copies of RNA per cell are usually reached through overexpression in human cell-lines? (any technique)

texts:
After 8 hours of online-research I was unable to find any info at all..
I was able to get some concrete copy numbers of DNA (e.g. plasmid) per cell after transfection of diverse transfection techniques, but I was unable to get any concrete copy numbers of RNAs that correspond to the transgene (of any overexpression technique).
My main interest would be the hek293T overexpression RNA levels using the viral plasmid, but concrete RNA copy numbers from any possible overexpression technique would be of interest. (for human cells like Hela, Hek, HepG2..)
Ideally I would need a reputable source, but 'gut-feeling comments' are welcomed as well.
In the end I would like to compare overexpressed RNA concentrations to naturally extremely high concentrated endogenous RNAs. Are these levels comparable, or are the (viral) transgene promoters that much more effective?
EDIT: Please also mind that the nucleus is a strong barrier to foreign DNA. Might complicate this answer.


texts: How to find PDB id of an amino acid sequence

texts: Suppose I have an amino acid sequence whose PDB id  is unknown. Is there in online server that can find the PDB id of the corresponding amino acid sequence?  is there any site that will find the pdb of a protein closest to the query protein?


texts: How would a warm winter affect maple sap production?

texts:
The past winter (2011-2012) was warmer than usual.

Trees are normally tapped in late February when the daily maximum temperature goes above freezing. However, assuming that there have been relatively few days with a maximum temperature below freezing, how would this affect the timing and quantity of sap flow?


texts: Is it easy to test human Flicker Fusion Threshold?

texts: How would you go about testing human flicker fusion threshold? Is the testable rate consistent in humans over time or volatile?


texts: Do users of CRISPR/Cas iterate or parallelize to try multiple guide sequences?

texts:
I've read about on-target efficiency and off-target effects in use of CRISPR/Cas9, and about tools that suggest good guide sequences. I am wondering: how many guide sequences do typical CRISPR users try -- i.e. is there any iteration or parallelism involved?

I think the answer is yes for some use cases, but I am not sure:

Knocking out one particular locus: There are only a few possible guide sequences, so you can just make a library that includes all of those and run one experiment, without iteration. You would not know which guide sequence worked best, though, but users may not need this information.
Knocking out one gene, no matter at which loci: Since there are many possible loci for indels, the key is to choose a locus for which the guide sequence is effective and produces the last off-target effects elsewhere in the genome. This would mean iterating/trying several of the top suggested guide sequences individually. These could be tried in parallel across several experiments.
Knocking out multiple genes, aka multiplexing: The user would want to find good guide sequences for each gene separately to avoid any interactions. This would reduce to the previous example above.

Is my understanding above correct?


texts: How does the genetic material differ between dizygotic twins and ordinary siblings?

texts:
I am going to give a rough presentation on twin studies.
The terms heritability and concordance are included already, but I struggle with understanding the difference of the genetic material of dizygotic twins and ordinary siblings.

While ordinary siblings evolved from different sperm and egg cells, I only know that dizygotic twins form when two different sperm cells fertilize egg cells of the same cycle. However, I'm not sure if these cells are identical products of the same meiosis process.

I appreciate your help and time.


texts: Is it tautological that all living humans descended from a single male and single female human ancestor?

texts:
Many popular science articles cite high sequence conservation of mitochondrial DNA and the Y chromosome among living people as evidence that all humans are descended from a single male and single female human ancestor.

Is sequence evidence necessary to make this assertion, or does it follow tautologically from the definition of speciation? What would a speciation pedigree look like for a species that does not pass through a single-individual bottleneck?


texts: During assaying an enzyme at high temperature, the substrate (Pectin) is degraded by the high temperature rather than by enzyme, so, how can I minimize degradation of the substrate by the temperature?


texts: What is this? In Florida. Found in plant bed under rosemary tree that gecko' enjoy hiding aloe plants also growing.

texts: Species identification of round soft outer shell


texts: Recalling memories by electrical impulses?

texts: I've read that in an experiment, a pair of stimulating electrodes were inserted into a blind man's visual cortex, and upon passing electricity, the phosphene phenomenon was produced. Is it the same with memory? Can each and every memory, of an individual be recalled by a similar method? And if so, in which region of the brain will the stimulating electrodes be inserted?


texts: Why don't mosquitoes target the visible blood vessels under the skin?

texts:
We can see numerous veins under our skin. Why don't mosquitoes suck blood from those vessels?

Why don't they use better option?


texts: How can you gain 1 lb of bodyweight from eating less than 1 lb of food surplus?

texts: A commonly referenced "fact" is that a caloric surplus of 3500 kcal is equivalent to a 1 lb gain in bodyweight. But I'm confused. If you get 3500 kcal worth of, say, fatty acids, which are 9 kcal per gram, then that's about 390 g, which is just under 0.86 lb. How can you gain 1 lb of bodyweight from eating a surplus of less than 1 lb? Am I missing something?


texts: Why use embryonic neurons to study protein knockouts/mutants in long term potentiation?

texts:
Just wondering if anyone had some ideas about the question in the title. I'm just wondering why some papers use embryonic cultures of specific brain regions for neurones to test the effects of knockouts/mutations on synaptic plasticity (for example, long term potentiation, LTP) instead of adult cultures?

Many thanks


texts: How fast do cancer cells divide (compared to normal cells)?

texts:
This question suggests that we have, on average, 50-70 billion cell divisions per day. I just read that cancer cells divide more often and are therefore more prone to radiation.

I am wondering, for a specific type of cancer, how fast cancer do cells divide (approximately) compared to normal cells. Does the ratio of cancer mitosis rate to the normal cell mitosis rate varies a lot?

I checked bio-numbers but there's not much data there.


texts: I'm using Promethease to examine genome data originally downloaded from 23andMe. Some genes I notice do not show allele information (eg. (G;G), (C;G)) and instead seem to be blank (-;-) like in the screenshot I provided. Can someone please tell me what this means? Thanks in advance.


texts: What is this thing that is growing in my yard? And should I get rid ot if?

texts:
I live in Wilmington, Delaware (Mid-Atlantic USA).  The north side of my yard is largely shaded by my house and grass is spotty.

Periodically when I go into the yard I will find as many as four pod-like things have opened on the ground.  I almost never notice them before this stage, the one time I did it looked like a patch of dirt until I stepped on it and it sort of shattered.

I'm baffled by it and my wife thinks it's some form of fungus.

We have two children under 4 and we are concerned it could be poisonous.  It certainly doesn't enhance our yard's attractiveness.

With that in mind, I have a handful of related questions:

What is it?
Is it dangerous?
How can I get rid of it, if I so choose?

Addendum:

I believe we have found an unopened example of what we've been seeing:


texts:
Ok, so this appears to be quite a mystery. Me and my girlfriend have 2 Guinea Pigs, 1 male and 1 female.

My girlfriend once picked up the female one and took her outside into our garden. The Guinea got scared for some unknown reason and jumped out of my girlfriend's arms and fell down hard.. That night, the female Guinea woke us up with some very strange sounds. She sounded like a chirping bird.

Since then, she sometimes repeats these sounds (most often at night, but not always). Mostly, we are puzzled as to why as there is often no apparent reason for her sounds. Also, when she makes the sounds, she appears to be in a trance-like state, making no movements at all.

Looking for the answer online I found many discussions on the subject like this one or this one. Mostly, the sounds (and the often mentioned trance like behavior) appear to be interpreted as either (1) alarm sounds, (2) loneliness sounds or (3) happiness sounds.

There are also recordings of it one Youtube, like this one.

What I was wondering:

Does anybody know about some actual research that has been committed on this subject? If so, what were the results?

I'm just so very curious to find out!


texts: What risk does the insulin pump hack carry?

texts:
Recently, a OneTouch system was hacked, potentially allowing any malicious attacks, draining the pump into someone's bloodstream:

  Jay Radcliffe, a diabetic and researcher with cyber security firm Rapid7 Inc, said he had identified ways for a hacker to spoof communications between the remote control and the OneTouch Ping insulin pump, potentially forcing it to deliver unauthorized insulin injections.

If this threat is real, what is the theoretical worst-case scenario for a patient with one of these insulin pumps? Is this actually directly life-threatening?


texts: Why Is The Toughness Of Skin Different On Different Parts Of The Body?

texts:
My cat was licking my arm with his sandpaper like tongue. It hurt and the area he was licking was slightly smarting afterwards. However, when he licks the palm of my hand the feeling is rather ticklish and results in no pain during or after.

We can pick up sharp, prickly, abrasive objects with our hands (palms/fingers) and even rub against them and have little to no damage incurred. However, if we do the same with say the back of our hand we are more likely to be injured.

I thought maybe the skin is thicker in our palms and that is resulting in our palms being more resilient. But, our palms are so sensitive to touch that it makes me think the skin is thinner to allow the nerves closer access to our environment.

Why is there such a stark difference in different areas of skin on our body when it comes to feeling pain and being susceptible to injury from scrapes, bruises, cuts, etc?


texts: Why does the insulin taken from pig when injected into humans causes allergy but not the insulin taken from bacteria?

texts:
At earlier times, insulin was injected to human patients that were taken from pigs and horses. But that caused allergy it seems.

But why is the insulin produced by the recombinant bacteria not causing such types of allergy?


texts: How old does a baby have to be before it can retain memories?

texts:
For most people (my earliest memories are of perhaps when I was 2 or so) their earliest memories would be when they were over a year old.

How old does the average baby have to be before it can retain memories?
Are there any preconditions that need to be fulfilled?


texts: Are two colors (red + blue) necessary for LED grow lights, or would either color be sufficient?

texts:
Below are some chlorophyll absorption spectra from other answers here. There is strong absorption at both the blue/violet end, and the red end of the spectrum, and presumably both of these contribute to steps in water splitting used in photosynthesis.
Do the two broad but widely-separated peaks correspond to different steps, so that both are required? Or is it sufficient to have light present in one band alone?
If both are required, how are they used differently?
If not, why do LED grow lamps have both? Would twice-as-bright light with either wavelength be just as effective and useful to plants?

That horribly un-natural purple light looks cool in high tech settings, but it's kind-of ugly in ones living room.
note: Originally I had though that Chlorophyl A and B corresponded to the two peaks, but clearly this is not at all the case. From here:

Both Chl-a and Chl-b primarily absorb red and blue light, the most effective colors in photosynthesis. They reflect or transmit green light, which is why leaves appear green. The ratio of Chl-a to Chl-b in the chloroplast is 3:1.

above: From this answer, also seen here.

above: x2 From this answer.


texts: Female preference for males who are already in a relationship

texts:
A common saying is that women are generally more attracted towards men who are already in a relationship, and this phenomena does seem to have its own place in popular culture that is not matched by a corresponding male preference for women who are already in a relationship.

From an intuitive viewpoint I think it would make sense from the woman's viewpoint in an system of information economics where the fact that a male is engaged in a successful relationship with another female, or several other females, might provide extra and positive information about the evolutionary value of the male.

But how about the possibility for a male to use the same trick?

Is there any empirical evidence for this behaviour at all either in humans or in other species, or is this just a cultural artefact in some human societies? If there is empirical support, is there a consensus on the plausible evolutionary pathways involved here?


texts: What terms or concepts are used to describe the morning metabolic phenomenon involving glucocorticoids, glucose, and blood pressure?

texts:
A recent conference report described using a vaccine-based strategy to blunt a surge of high blood pressure that occurs between 5 and 8 a.m.  Apparently most heart attacks and strokes occur during this period, which makes this of special importance.  Presumably this ties in with preceding work showing that ordinary blood pressure medication is more effective when taken in the evening.
When I read about the "dawn phenomenon" (reduced glucose tolerance in type II diabetics) it is often treated in isolation.  Because glucocorticoids are a factor in the dawn phenomenon, it makes sense they could be involved in raising blood pressure during the same period.
This makes me wonder how much more I have missed.  There seems to be something special about the morning period in metabolism, something deserving of some name as fundamental as "sleep".  Yet I don't have one to use, and I don't know why it evolved, how its timing is determined, what its advantage is, whether it correlates with worker productivity, whether early risers and late risers and night shift workers have this period at the same time and so on.  Medical labs typically open at 7:30 a.m. - do they reference the time in relation to any of these phenomena?
Thus the question: what terms or concepts would you suggest to help someone research and pull together existing knowledge about the metabolic changes that occur in the morning?


texts: How can we calculate the constants of the SIR model?

texts:
I am not a biologist by profession, but I am attempting to implement a simple SIR model from the following paper. The paper assumes the following constants are known:

rc    = growth rate of susceptible group S

k     = carrying capacity of susceptible group in absence of infection

alpha = max value of per capita reduction rate of S due to I

a     = half saturation constant

gamma = natural recovery rate from infection

delta = death rate of recovered population

I found some coronavirus data from the following source, and I plotted the Italy data in particular:

Can I calculate the constants above from this type of data?
Is it a good assumptions for these "variables" to be constant?

Here is my attempt of the model with the constants given in the paper


texts:
It's well-known that indiscriminate use of a drug leads to resistance. My question is what the limits on resistance are. It seems obvious that there must be limits: for example I can hardly imagine a tiger evolving "resistance to bullets", and similarly I can hardly imagine a microorganism evolving resistance to heat treatment @ 1000 degrees celsius (surely its proteins must long denature before then).

Are there methods of killing microbes that cannot be resisted? If so, can we make similar cannot-be-resisted drugs?