texts: Can you predict what the metabolites of pipradrol would be? Are they similar to those of methylphenidate?

texts:
As these drugs are structurally very similar, I am curious about how the body would handle them. Ritalinic acid is a major metabolite of methylphenidate, but that's about all I know.

Thanks

Methylphenidate:
https://en.wikipedia.org/wiki/Methylphenidate#/media/File:Methylphenidate-2D-skeletal.svg

Pipradrol:
https://en.wikipedia.org/wiki/Pipradrol#/media/File:Pipradrol.svg

Ritalinic acid:
https://en.wikipedia.org/wiki/Ritalinic_acid#/media/File:Ritalinic_acid-2D-skeletal.svg


texts: Can we spike with a different enzyme to a SYBR Green Master Mix?

texts:
I followed the standard SYBR Green Protocol for doing a qPCR. For which I used

10 uL of 1X SYBR Green Master Mix
Forward Primer and Reverse Primer (each at a final conc. = 8.5 uM)
Template (unknown concentration from an aptamer selection)
Made to 20 uL with water.

Performed the PCR amplification using

95 C Initial denaturation
95, 68, 72 - cycled 35 times.

But, one set of sample from my aptamer selection (probably high GC content) did not amplify at all. I checked on an agarose gel too.
Important Notes:

My primer conc. is intentionally high - I have always amplified with such concentrations and it works perfectly using Vent Polymerase.

My annealing temperature is also high at 68 C because my aptamer sequences tend to be GC Rich.

Using Vent polymerase my amplification is very strong

On reading notes from vendors, I found out that the polymerase in the mastermix to be some variant of Taq Polymerase[1][3] (varies from vendor to vendor) and also it is known to poorly amplify GC Rich Sequences[2].

https://www.thermofisher.com/order/catalog/product/4309155

https://www.thermofisher.com/order/catalog/product/N8080241

https://www.fishersci.co.uk/shop/products/powerup-sybr-green-master-mix/15366158

Hence, I wanted a suggestion from anyone working with aptamers, or if you have experience working with GC rich sequences on how I could amplify my sequences.
Much appreciated if I could have an answer before next week.
Thanks a lot for your help!!!


texts: Which ingested allergens can be transferred to a partner via bodily fluids?

texts:
Can some allergens, such as peanut traces, appear in bodily fluids (saliva, sweat, semen, vaginal secretion) after ingestion?

I would like to know in particular intake of which allergens should be avoided to prevent allergic reaction of a partner due to contact with bodily fluids.


texts: Production of processed Insulin in bacteria

texts: Genetically-engineered bacteria are used to produce insulin in industry, but as far as I know, the bacteria can produce only proinsulin. Why is that? What happens in the human body in order to make functional insulin, that can't happen in some microorganisms? In the body proteases cut some at amino acids, and cleave the polypeptide while other enzymes create disulfide bonds.  Why is there no bacteria in the industry that can do the same? It's not possible for some reason or in other words — can such a bacterial strain not be engineered?


texts: Identification of an insect found near Shirdi, Maharashtra

texts: I found the insect nside house near Shirdi, Maharashtra. I have captured the image


texts: How are neurons selective towards specific stimuli?

texts:
I've read several papers that mention that there are specific neurons that are activated for specific things (e.g. neuron A activate only when horizontal lines appear, neuron B activate when certain sound appear, etc).
How does this happen over time (unless the neurons are "born" with certain "affection" towards stimuli) and what is the mechanism that allow it? I understand that it's probably not some conformational change in proteins since the activity has to be really fast- so how can an electrical signal be selective?


texts: What is background signal in a Western blot?

texts:
I have done a western blot and I want to remove the background signal when doing densitometry analysis of my protein bands of interest. I have read some articles online such as this one regarding high background in western blots. I have learnt that there are many factors that can contribute to high background in a western blot. However, I am still not sure what exactly is defined as background. Does it refer to non-specific antibody binding on the membrane, or can it also refer to regions on the membrane where there is no binding to any protein?
Any insights are appreciated.


texts:
I visited a bird enclosure close to where I live in Australia. The enclosure had several different species. The birds that stood out most were these doves sitting right along the fence railing, making a deep "Wo-wo-wo-woo" sound. That and also I thought they looked and sounded similar to Spotted Doves.

Does anyone know what the species of this birds may be?


texts:
In a handout the following is stated:

  Amylose is insoluble in water, therefore a good storage compound e.g. in stroma of chloroplasts

This is with regard to the chemical structure of the molecule.

However it has left me wondering, what is it intrinsically about the structure of a molecule that makes it soluble/insoluble in water?

My thoughts at this stage are perhaps to do with whether the molecule is hydrophobic, and if that is the case - how is amylose hydrophobic?


texts: Are glycoproteins and glycolipids present only on the cell surface membrane?

texts:
I haven't read this being stated explicitly, however whenever I read about proteins and glycoproteins this seems to be implied. For example, in this Wikipedia article,

  Lipid and proteins on the cell membrane surface often have short carbohydrate chains protruding out from the cell surface, known as glycolipids and glycoproteins.

My question is, is this the case? And if so, why would they only be present on the cell surface/plasma membrane. Would they not be useful elsewhere in the cell for example for vesicle trafficing as receptors for targetting sequences?

One idea I have is that, to the best of my knowledge, the enzymes for glycosylation are present in the endoplasmic reticulum and Golgi lumens (oligosaccharyl transferase in ER, etc) so glycosylation would only occur on the part of the protein/lipid that is topologically outside of the cell, however this brings up more questions:

This does not exclude glycoproteins from sticking into certain organelles (i.e. on the other side of the membrane to the cytosol) which is also topologically equivalent to the cell exterior.
Why would there not be glycosylation enzymes on the cytosolic side?


texts: What are the molecular/cellular basis of pruritus ?

texts:
Could someone please explain the cells and molecules involved in the clinical phenomenon of pruritus ?
I'm interested in a general view about the subject, but detailed answers will be appreciated.


texts: Why does a cell produce a lot of p53 protein only to later degrade it?

texts: It is known that the half life of p53 is short and so does that play a role in the amount of energy the cell would need to expend to degrade all the p53? By that does the fact that the half life of p53 is so short does that just allow for the cell to not have to expend very much energy to degrade the p53 so in a way the cell doesn't "mind" having to degrade the p53 since it wouldn't take a lot of effort?


texts: Why is Turner syndrome rarer than Klinefelter syndrome?

texts:
Turner syndrome occurs in 1-1000 to 1-5000 females, and Klinefelter syndrome occurs in 1-500 to 1-1000 males.

Why is Turner so rare even though they both are caused basically by the same mechanism?


texts: Has autogamy been observed in any animals?

texts:
By my understanding, autogamy, i.e., reproduction that is sexual, but with both gametes contributed by the same individual, is not at all uncommon in the plant kingdom.
Does this also occur anywhere in the animal kingdom?


texts: How exactly does mitotic recombination help repair damaged DNA?

texts: I understand the utility in crossovers during meiosis, but how exactly is mitotic recombination useful for dealing with DNA damage? If one sister chromatid is damaged, the other can supply a functional replacement for the defect part, sure, but then the donor chromatid will lack that section. Isn't that a zero-sum game? What am I missing?


texts: Should you perform an ordination (such as PCA) of abiotic variables before a Redundancy analysis (RDA)?

texts:
I have a dataset of viral 'OTUs' across various sample points from different sites/times.

I also have meta-data collected at these same sample points, for things like temperature and the concentration of key chemical compounds.

My goal is to identify if these (or some of these) abiotic variables correlate with the variation in the OTU community diversity- for now I am planning to do an RDA.

What I am wondering is whether or not it makes sense to conduct ordination on the abiotic variables before doing the RDA? I have done a PCA on these abiotic variables and it is clear that these variables alone clearly do not cluster in any sort of recognisable pattern (for example if you colour them by 'season' there is no clear clustering at all).

So I was thinking that perhaps doing an RDA would not be valid, because if the abiotic variables don't cluster logically in an ordination of them alone then surely it doesn't make sense to plug this data into an RDA?


texts: Why has malaria only now started to develop resistance against artemisinin?

texts:
Why has malaria only now started to develop resistance against artemisinin, considering the compound has been in use for about two millennia in its herbal form in China?

The WHO has reported:

  In recent years, parasite resistance to artemisinins has been detected in four countries of the Greater Mekong subregion: Cambodia, Myanmar, Thailand and Viet Nam.

However, the compound artemisinin has been used in its herbal form since at least around 400AD, when it was documented in the well known medical text 肘后方.

What are some reasons that malaria has only begun developing resistance now?

I would imagine that modern artemisinin would be more effective in completely eliminating malaria, as compared to use in its traditional herbal form. This means semi-resistant strains would more likely be killed before they are able to spread or develop resistance any further.

(archived WHO report)


texts: Detecting cancer in the hyperplasia phase using image processing and SEM

texts:
I was wondering if it possible or have someone tried before to use SEM or some other spectroscopy to detect an cancer evolvement in its hyperplasia phase:

It sounds like a good way to do it? I guess that's how biopsy works, but maybe there is a way to do test people in the risk groups using this method.


texts: What is the impact of sertraline on white blood cells?

texts:
This simplified video and RT.com article discusses how the mechanics of the death of a white blood cell can be useful as an "alert mechanism" to other white blood cells of an incoming infection.

Also in the article it describes how this same notification mechanism might enable the transmission of certain types of pathogens and it has the following quote:

  "We found that a commonly used antidepressant can block this whole process and an antibiotic can promote this event,” said Ms Atkin-Smith.

The full report is available here.

Can anyone explain, (with a summary in layman terms) the impact of Sertraline on white blood cells?

Does taking Sertraline increase the risk of susceptibility to illness, or decrease it?


texts:
TLDR? Just read the bold bits!

I started with Darwin's Origin of Species, and then read Dawkins's first three books The Selfish Gene, The Extended Phenotype, and The Blind watchmaker (I just started River out of Eden).

Dawkins talks of Gradualists and Punctuationalists as if their views are incompatible but my initial understanding of Darwin was that both of these are true. My understanding is that if you look at an individual line of heredity then you will see a very consistent and gradual change through the generations (at the mutation rate), but if you look at the population as a whole you will see "periods of rapid evolution".

To me this seems easy to reconcile. Imagine a gene for fur thickness in polar bears, if each nth generation has a 'random' mutation for thicker or thinner then for each line of heredity you'll see a random walk about the starting point. Most of them will go up a bit, then down a bit, and end up close to where they started, some will be a bit further away, and a small number will be far away (much thicker or thinner fur) in a Gaussian distribution. So any random sample from the population that happens to become a fossil is most likely to be in the middle (i.e. unchanged over many generations).

Now if there's a sudden environmental change, or a one-off freak event such as a very cold winter, say that only the 10% with the thickest fur survived this cold winter (and perhaps a very small number of others who got lucky). Now very quickly within a few generations, that thick fur gene will dominate and as the population grows back to whatever size the environment can sustain it will be present in much greater absolute numbers than before the selection event. When looking at random samples of the population throughout this period, you might conclude that there has been a "period of rapid evolution". If the change is more gradual than a single sudden event, for example it gets colder over 500 years, each year the ones with the thinnest fur die off and the thicker fur genes get more popular in the population. This would appear to be a very rapid period of evolution, but really all the evolving happened gradually, long before the selection event.

My question really is what's wrong with this view of things? Dawkins seemed to anticipate all my thoughts and objections while I read his books and provided explanations, except for this one. This kept nagging at me the whole time and he never mentions it at all. I can't imagine I'm the first person to think this way (especially since Darwin himself pretty much said this) so why doesn't Dawkins explain it (either as correct or as incorrect with the reasons why)? Can someone please explain it to me either way?


texts: I am considering to send some samples overseas in Eppendorf cups. They are the standard plastic cups of 1 to 2 mL capacity. Of course they may tip over during their journey and I'd like to know how well they seal or if there is any danger that anything leaks from inside the cup. The samples are fixed in alcohol if that is relevant.


texts: Identity little brown lady bugs taking shelter in my home

texts:
Can someone please identify this little creature for me. They are appearing more frequently in my room. What are they doing here? Could it be those basic needs and requirements?

The size is about 2 x 1 millimetre. My location is the Netherlands. I am on the 20th floor of a flat. The season is now heading towards end of spring.


texts: Is there any evidence for sperm parameters being connected to fitness of the offspring produced by that sperm?

texts:
In most (if not all) sexually procreating species the amount of offsprings a male can produce is limited not by the amount of sperm he can produce, but by the amount of eggs his sperm can fertilize (with rare individual exceptions).
Because of that the optimal strategy would be to fertilize eggs with the best sperm.
Therefore it is reasonable to assume that there would be adaptations making sperm with deficient genes less likely to fertilize an egg.
But is there any evidence of this happening? E.g. would fertilizing eggs with less motile sperm (potentially with IVF) produce a less genetically fit offspring or result in a miscarriage?


texts:
I am investigating the public data of this.

Its specification

201 2 360 650000
201.dat 212 200 11 1024 972 -519 0 MLII
201.dat 212 200 11 1024 982 30947 0 V1
# 68 M 1960 2851 x1
# Digoxin, Hydrochlorthiazide, Inderal, KCl
# The PVCs are uniform and late-cycle.  Junctional escape beats occur following
# episodes of ventricular trigeminy.

The data is taken from the interval $[200000, 205000]$ in the following picture with the sample rate 500 Hz.

There seems to be more than Premature Ventricular Contractions (PVC), extrasystoles, so possible ventricular tachycardia.

The same patient has six minutes later this

I think you can see clearer here those PVCs, when the ventricle is starting to contract too early.

Both are very pathological situations.
How can you differentiate between the two?

Are there PVCs in both pictures?


texts:
I found a dead scorpion on the sidewalk today, and brought it home, being careful not to touch its stinger. Bees can sting even after they are dead, if you step on them in such a way that it pushes their stinger out.

Does the same apply to scorpions?  Do I need to be careful not to touch its stinger?


texts: Help with identifying creature found in brazilian beach

texts:
I don't know if this is the correct place, but I've been looking for someone
that could help me identify this creature I found while I was looking for shells. There are three mollusk-like "beings" stuck in some sort of big seed (it's definitely not a rock nor a part of their body). They
 can "spin" around with the arm that is stuck in the seed, and they continuously take some blood red hair-like tentacles in and out of a shell.
I shot a video of it,  the link is right below. Please ignore all background audio, I couldn't find somewhere without people.
This "being" was found today, at roughly 6pm, washed ashore in the beach I'm visiting - "Praia Grande" in Brazil.
Another peculiar thing is that tap water makes the "things" close for a while, and sea water doesn't do much. Also, as they dried, the single tentacle hair became multiple smaller ones. They keep coming in and out, without stop.

If anyone could give me a shine on what that animal is, it would be super helpful!

https://drive.google.com/file/d/1-rSk-WVb6pkS98Npp1VF3Aq8xxXPKiuc/view?usp=drivesdk


texts: What is the gas inside a Capsicum pepper, and how does it get there?

texts:
Every time I make fajitas, I cut into bell and chili peppers and notice how hollow they are.  I always think to myself: what is the gas inside this pepper, and how does it get there?

Perhaps Capsicum peppers are porous.  I did a little kitchen experiment to try to find out.  (I'm afraid I don't know much about biology, so this "experiment" is likely to be flawed in at least one basic way, but I figured I should at least try to figure it out myself before asking.)  Here's what I did:

I filled a small container with water and submerged an uncut Anaheim pepper.  It was quite buoyant!  I put the lid on the container so it would stay submerged.  It didn't seem to become any less buoyant, and its interior didn't seem to fill up with water.  No bubbles emerged from the pepper, as least as far as I could tell.

So air doesn't seem to easily pass in or out of the pepper.  And of course they don't grow around air, so how does the gas get in?

Here are my guesses:

The fruit is porous to air, but the holes are small enough that, in my experiment, they were sealed by the surface tension of the water.
The fully isn't porous to air when fully grown, but it is porous to air while it's still developing.
The fruit does some amount of photosynthesis, and the air is waste oxygen.


texts: Why does not the host produce any immune response to antiserum antibodies?

texts:
When an antiserum is injected to a person to protect oneself from a certain disease, the antibodies in the antiserum come from another organism. The question is:

Why don't the injected antibodies cause an immune response in the individual?


texts: Do plants experience the following feelings

texts:
I am not a student of biology,in other words I have not read biology much.

But I read that plants have life and so my question is the following:

  Suppose I take two saplings of two different varieties of hibiscus(or any other tree variant) and I put them in the same pot and allow them to grow up.
  Suppose they grow up and become well grown plants after say 4-5 months.
  My question is:

  Will the two saplings experience any feelings for each other,in other words will they become friends or share any relation with each other.
  Suppose one of them is attacked by insects and its growth gets shunted,will the other plant also experience some feeling for it.

  If I uproot one plant will the other one feel lonely or any other kind of feeling as if its counterpart is missing.

If someone cares to answer the above questions,I would be very grateful.
Thank You


texts: How do you design a drug to be delivered to the CNS?

texts:
I have just started reading up on structure-based methods for drug design (this is completely not my field so apologies for stupid questions that will be coming along!)

Clearly, some drugs are designed to target the central nervous system. However, I understand that the extracellular fluid of the central nervous system is separated from the blood by the "blood-brain barrier" which restricts the passage of large molecules between the two systems.

My question is : how do you design a drug to be delivered to the CNS?


texts: Average Amount of normal stem cells in a given organ

texts:
I am trying to find an estimate of the amount of normal stem cells in an organ, because I need it as initial conditions for a model to estimate the secondary cancer risk after radiotherapy. I know that there are different types of stem cells, but I am interested in any stem cells that have the potential to become malignant.
I have been looking through the web and have tried most keywords that I can think of to find a paper that estimates this amount, but I have been unsuccesful.
Has anyone around here ever come across literature that presents an estimate for normal stem cells in an organ?


texts: Can you gain valid toxicological data about a detergent in cell cultures?

texts:
I just looked at a paper that in one assay tested a variety of chemicals and chemical mixtures against human cell cultures. They exposed HEK 293 cell cultures for 24 hours to the various chemicals.

One aspect I find dubious is that the chemical found to be the most toxic is a detergent. I only have negligible experience with cell culture experiments, but my assumption here would be that any kind of detergent would obviously disrupt the cell membrane and kill cells. And this kind of mechanism is not really transferable to actual humans, something that only disrupts cell membranes wouldn't be very effective against the entire organism.

How valid are toxicological experiments made in cell cultures with substances that are detergents or have similar effects? Does this make it impossible to draw any conclusions about toxicity as I suspect? Or can you still gain valid toxicological data about this kind of chemical from cell culture experiments?


texts:
I am thinking how clot retraction and fibrinolysis work together.
I think that clot retraction is a process that gets clot towards fibrinolysis process.
Fibrinolysis process then lyses the clot.
However, I am not sure if it is so simple.

Some seems to be discussing about how to differentiate start of fibrinolysis from clot retraction morphologically.
So they probably seem to be at this stage similar processes visually, but not functionally.

What is the function of clot retraction?


texts: Is there a feasible way to create a large number of long random DNA strands?

texts: Suppose I want to create a large number of random DNA strands (maybe a million, or a billion, or even something close to all $4^N$ possible sequences of $N$ base pairs).  Is there an experimental way to do this?


texts: Beetle with long, slender iridescent green body and orange legs

texts:
I recently saw this beetle while on a trip in central Texas, USA (in a rural area just before sundown). The body was about 2-3 inches long (compare to nearby chair leg and floorboards) and had a long body. It was very vivid green, and its upper legs were very bright orange (which made me wonder if this is aposematism). Its antennae had very uniform half-circle arcs (instead of the uneven parabolic shape often seen in cockroaches and similar common insects) and didn't seem to bend besides being rotated ~5 degrees up and down.

It carried itself pretty high off the ground, perhaps half an inch between the belly and ground-level. It seemed to move fairly fast, but not as fast as a cockroach. It didn't fly in the few minutes I observed, and didn't seem like it could fly since the shell appeared solid, but I might have mistaken well-fitting sheaths for fused ones.

What is the most likely species? Is it poisonous?


texts: Stability of DNA double helix conferred by base stacking

texts:
Our school textbook states that base pairs confer stability to the B-DNA double helix in two ways:

1) Hydrogen bonding between purines and pyrimidines of opposite strands.

2) "Stacking of one base-pair plane over the other"

It's the second point that I'm not able to understand. I did try looking it up on the internet, but I'm not able to find anything relevant in that regard.

So could someone please try explaining that second point to me?


texts:
Nucleotides are made up of a heterocyclic nitrogenous base, a sugar (only ribose or deoxyribose), and a phosphate. In nucleotides, obviously the nitrogenous base matters as its variations dictate the production of certain amino acids, and the sugar can only be ribose (in RNA) or deoxyribose (in DNA), but does the type of phosphate matter? I've seen that a nucleoside describes the nitrogenous base and the sugar alone, and there are nucleoside monophosphates, nucleoside diphosphates and nucleoside triphosphates.

Do these three variations differentiate; when it dictating the production of amino acids; when looking at any sort physical variation; in any sort of way; or are all three just the same as each other??
Also, do all of the phosphates have to look like this?
(https://en.wikipedia.org/wiki/File:Phosphate-group.png). Or can they look like this (https://en.wikipedia.org/wiki/File:Phosphodiester-group.png). If they can look like the second image, then similarly to the question above, does it make any difference?


texts: Is it possible to express both the MHC class-1 and MHC class-2 both in one cell?


texts: Specific examples of signalling pathway using logical 'OR' and 'AND'?

texts:
I have read here that
"signals from two different pathways may be needed to activate a response, which is like a logical "AND." Alternatively, either of two pathways may trigger the same response, which is like a logical "OR."
But no example is mentioned. I want to know some specific examples in which cell signalling uses logical OR and Logical AND. Any references will be appreciated.


texts: How can I search through literature databases for words containing a * when the asterisk is read as syntax and not part of a query?

texts:
I'm exploring the literature on microRNA, where it is common for the less utilised strand of the miRNA duplex to be referred to as the miRNA* strand.
However, I am experiencing some issue searching for literature sources, as the databases I use for my searches (Web of Science, Google Scholar) utilise an asterisk as part of the search syntax rather than part of the query itself. This leads to any search for "miRNA*" yielding every paper on miRNA in general.
I am getting by for now using alternate search terms and other papers references, however it would be excellent if someone knows how to tell these databases that the asterisk is part of the query and not syntax.


texts: Are there any species whose descendants can meet their ancestors from 100 generations back?

texts: I.e. Humans can sometimes meet even their great-great-grandparents, but are there any species that can be alive at the same time as their great-great-……-great-grandparents? I imagine it would be those species with a long lifespan and an early age of first reproduction.


texts: Is there a law that defines an upper bound for the speed of growth of an organism?

texts:
I was wondering if there is some biological law (or chemical/physical law for that matter) that limits how fast an organism can grow.

I know that the growth of a plant is often restricted by the deficit of some nutrient (e.g. phosphorous). Phosphorous fertiliser over comes this. However, if one were to give a plant its optimal ratio of nutrient, sunlight, CO2, etc... we could probably not increase its growth speed by a factor of 1000, by increasing the dose.

Why is this?

Is it because of the speed at which cells can replicate? or the speed at which light can be converted into chemical energy? or the speed at which minerals can be absorbed by the plant? or is it just a habit rather than a law?

Is it possible to calculate the upper bound of growth for an organism (or specifically any given plant)?

Please excuse if my terminology is rudimentary.


texts:
After reading de Waal's "Our Inner Ape", I'm left with the impression that chimpanzees would easily drive away or kill-off bonobos, if they were to compete for the same territory.

Have there been any instances of that in the wild? Or have their habitats always been completely separated by the Congo river?


texts:
In my class we were told that adrenaline (or epinephrine) causes vasoconstriction.
My question was I had always thought that people took this via an EpiPen when they were having an allergic reaction.

So I thought it would make sense, that it would dilate vessels, because this will allow more air through. Or does the constriction help because it tightens the vessels in the throat allowing a reduction of swelling?


texts: What is the Giemsa staining of chromosomes?

texts:
I got the question in my exam and wrote the following and I do not understand what is wrong in it:

  Giemsa staining is a staining method to stain particularly malaria and other parasital diseases. G-bands occur because Giemsa stain
  consists of A,T rich material i.e. poor gene such that dark and white
  bands occur. Each chromosome has an unique reaction to Giemsa staining
  so G-bands occur.

0 points. I do not understand what's wrong with it, since in their comments about the same question in my first exam they wrote also the extra questions: What are G-bands? How are they formed and why? This time I answered the given things and got zero mark.

Probably, the mistake was that I did not answer to the question in the scope of medical Biology in some way. However, I am not exactly sure what it is exactly.

How would you answer to the question when you know that the course was about medical biology?

Please, add the tag Giemsa.


texts: How does GTP help in the step of codon recognition?

texts:
The anticodon of an incoming tRNA base pairs with the complementary mRNA codon in the A site.Hydrolysis of GTP increases the efficiency and accuracy of this step.
How does GTP do so ?


texts:
I read that lack of action leads to muscle atrophy , I experienced same when I had a cast for hand fracture. So how far this atrophy go, who decides minimum size of muscle due to lack of activity, for example in coma patients.
Which part to brain or body signals muscle atrophy and upto what limit it should go?


texts: While learning about deamination, I learnt that excess amino acids must be converted to urea and excreted, since the nitrogenous group can alter the pH and affect proteins. But shouldn't the pH stay the same since they have NH2 that becomes ammonia as well as a carboxyl group (weak base and acid). So why are amino acids deaminated?


texts:
When I was in high school (30 years ago), I took a biology class, and the instructor showed us an Ishihara color test for color-blindness. (This is the "hidden numbers" test.)

What I thought I saw once or twice was two different numbers* that had been embedded in the same slide. Were there slides in the test that had two or more numbers, or was I hallucinating?

[EDIT:] * "Two different numbers" means "different numbers in different colors."


texts: Blood and hair follicles from 25 people put on the Moon; enough to regenerate a human population?

texts:
Discussion on the question Why were blood and hair follicles from 25 people put on the Moon? calls into question whether this is a stunt or might have any basis in science.

There's two parts to my question:

If somehow preserved well, do hair follicles and blood samples from a group of humans provide sufficient coverage alone to reconstruct a human population as far as the DNA content is concerned? Ignoring that you don't have an egg to put it in, is enough DNA present, or would there be key bits of DNA missing that you'd need a germ line sample in order to get? I suppose this can be asked as "can we clone people from blood and hair follicles alone?"
Would 25 individuals be enough to obtain a viable population of clones?

Background from the linked question:

The Wired.com article A Crashed Israeli Lunar Lander Spilled Tardigrades on the Moon says:

  Spivack had planned to send DNA samples to the moon in future versions of the lunar library, not on this mission. But a few weeks before Spivack had to deliver the lunar library to the Israelis, however, he decided to include some DNA in the payload anyway. Ha and an engineer on Spivack’s team added a thin layer of epoxy resin between each layer of nickel, a synthetic equivalent of the fossilized tree resin that preserves ancient insects. Into the resin they tucked hair follicles and blood samples from Spivack and 24 others that he says represent a diverse genetic cross-section of human ancestry, in addition to some dehydrated tardigrades and samples from major holy sites, like the Bodhi tree in India. A few thousand extra dehydrated tardigrades were sprinkled onto tape that was attached to the lunar library.


texts: Isoprenoid Diphosphate Concentration in Yeast saccharomyces cerevisiae

texts:
Isoprenoid  Diphosphate(IPP) is an important metabolites which is precursor in lot of secondary metabolites like Dolichol diphosphate, ubiquinone, prenylated proteins and carotenoid (not synthesized in s cerevisiae).

What is the average concentration of IPP present in yeast per gm ?


texts: What are the constraints when growing an artificial brain?

texts:
Are there any experiments on growing artificial brains from brain tissue?

What are the constraints? Will such tissue grown to the mass greater than that of human brain surpass it in intellect or it would need additional conditions?


texts: What does units/mg mean for Streptavidin

texts:
I got streptavidin for surface reaction. The label says "biotin binding: 16 units/mg". What does units/mg mean?

Does it mean "1 mg biotin can bind to 16 units SA"?

How much is the unit here?


texts: V(D)J recombination on homologous chromosome

texts: V(D)J recombination is known to recombine IG locus of a B cell. Is anything known about how the recombinations on two homologous chromosomes are connected? For example, are the selected V(D)J couples(triples) the same on both homologues?


texts: How do ion channels transport only specific ions?

texts: Ion channels, such as $Na^+$ channels and $K^+$ channels, are higly specific for ion permeability. But how do these channels achieve and maintain this specificity? Like how does a $K^+$ channel transport only $K^+$ ions (same for other channels like $Na^+$, $Ca^{2+}$, $Cl^-$, etc. channel)?


texts: How do cells determine what size to grow to before dividing?

texts: How do cells determine size to grow to before dividing?


texts:
I was wondering if anybody knew of the function and process of the TCTE-1 receptor during the binding of a sperm with an egg. The only think I know of TCTE-1 is that it is a species-specific receptor.
I also know that it's removal will render homozygous males infertile. I know that researchers are experimenting with mice to study TCTE-1.


texts:
Disclaimer: I have an academic background in computer vision but not biological vision.
Background: Classical computer vision is concerned with images from cameras that have a fixed exposure time for all pixels. During this exposure time, each pixel is essentially counting photons. This photon count then translates to a bitmap (usually 8 bits per pixel for monochrome cameras) which can be displayed on monitors.
However, the human/vertebrates brain does (afaik) not operate on integers or floating point values but spikes. Consequently, the brain must convert light to spikes for further processing.
Biologically inspired machine vision:
Let me quickly present you the simplified working principle of two major approaches of biologically inspired machine vision. They are the inspiration for this question.

Event Camera: The event camera has independent pixels that respond to changes in their logarithmic intensity $L = \log(I)$ ("brightness"). An event/spike is triggered at a certain pixel as soon as the brightness increment since the last event at the pixel reaches a threshold.
Formally, let $e_k = (\mathbf{x}_k, t_k, p_k)$ be the event at pixel $\mathbf{x}_k=(x_k, y_k)$ at time $t_k$ with polarity $p_k\in\{+1, -1\}$ as the sign of the brightness change. Then an event $e_k$ is triggered if
$$
L(\mathbf{x}_k, t_k) - L(\mathbf{x}_k, t_k - \Delta t_k) = p_k C
$$,
where $C>0$ and $\Delta t_k$ is the time elapsed since the last event at the same pixel. C is the contrast sensitivity and determines how much the brightness has to change to trigger an event/spike. This introduction is adapted from section 2.4 of this survey. For a more visual explanation see this introductory video.

Consequence of this working priciple: This camera only generates output when there is motion in the scene. Furthermore, it is not possible to reconstruct the actual intensity given spikes/events of an event camera. This is because the camera only generates output at intensity differences (it is a differential sensor).

Spike Camera: This camera also has independent pixel much like the event camera. However, each pixel integrates luminance intensity over time and emits a spike whenever a threshold is reached. This means that it essentially emits spikes to a rate proportional to the light intensity. More formally, let $I(t)$ be the intensity of a pixel at time $t$. Then a spike is generated at that pixel when
$$
\int_0^tI(\tau)\text{d}\tau\geq \phi
$$,
where $\phi$ is a threshold. More details are given in section 2.1 of this paper. Also have a look at the supplementary video for a visual impression.

Consequence of this working principle: Intensity is conveyed via rates of spikes. This rate is proportional to the measured photocurrent. Thus it is possible to reconstruct the true intensity at a pixel. Unlike the event camera, this camera also generates spikes when the scene is static.
My question: Can the spike generation mechanism of vertebrates vision be explained with these working principles? If not, is there another spike generation model that can be formulated mathematically?
Why I am asking this question: Literature regarding both cameras argue with biological inspiration but I have not found any evidence that either one of those approaches actually mimic the working principle of vertebrates' eyes. Any pointer to publications are welcome.


texts: I want to replicate an experiment in cell biology, and I have a question about centrifuge RPM vs. x g

texts: https://med.stanford.edu/news/all-news/2019/10/cytoplasm-of-scrambled-frog-eggs-organizes-into-cell-like-struct.html  This is the experiment which I want to replicate.  In the article describing the experiment, they said that they used a centrifuge capable of 12000 x g for 15 minutes.  I was wondering if I could possibly use a centrifuge with lower x g for a longer time interval and get the same result?  Like...possibly 6900 x g?


texts:
I am aware that each enzyme generate a certain amount of misproducts.
This is well documented, for example, for the DNA polymerase.

I am interested in enzyme involved in biochemical processes, so for example methytransferase, oxidoreductase, carboxylase and so on.
I have been looking for any reference that could report the error rate or the amount of misproduct for any of these enzymes, but I was not successful.

Does anyone know a reference reporting the error rate, or any other information about the misproduct generate by these enzymes?

EDIT

I will try to clarify a bit better my question.
Let's assume that we are considering an enzyme that add a methyl group to a molecule, we can choose propionic acid for example.
In theory the correct product would derive from the addition of a methyl to the C3.
For the biochemistry study we know that the activation energy is decreased by an enzyme for example by orienting the molecules in the right way to react with the second molecule.
Therefore, if the enzyme in question will not be able to orient the molecule in the right way there is a certain probability that there will be a mis-product.
For example the methyl group could be added to the C2 and not the C3. Now. the probability for this process is quite low, but it cannot be excluded from happening.
My question is, if there is anything known about this type of error rates in the different type of enzymes.

I hope this make things a bit more clear

EDIT 2

Lets consider the imagine below that was taken from here

In B you can see the interaction of the active site of the enzyme with a substrate (for the example it does not matter if it is the real substrate or an inhibitor). I would say that among al possible interaction that this active site can make with substrates there are some much more likely than others. An hypothetical chart could be created considering the free energy of the complex enzyme-substrate, higher the free energy lower the stability.
Therefore among all possible enzyme-substrate combination we will have just few possibilities that have a low free energy. In the first place we will find the "correct" substrate, then we will find eventual competitors and other molecules that have similar chemical features as the substrate. Even though with low probability these interaction, enzyme-competitors, will happen.
This might led to the formation of "unwanted product" that I refereed to in my question as "misproduct".

I am interested in reading some paper that are considering thie phenomenon and also quantify its rate. I am also curious if this phenomenon can happen with different rates in different enzymes.


texts: Do all anabolic reactions involve condensation?

texts:
I know that condensation is one example of an anabolic reaction (building macromolecules from monomers), but do all anabolic reactions involve condensation? Or is there an example of an anabolic reaction which isn't also a condensation reaction?
Could anyone elaborate on this please?


texts:
How is the rate of transcription influenced by temperature? More precisely, I am looking for an article who quantitatively measured the rate of transcription of an "average gene" and show how this rate is influenced by temperature.

On this question @Chris found this article where such measurement were performed but they were using some arbitrary unit (as it as been pointed out by @shigeta here) that cannot be related to any comprehensive unit such as "mole of amino acid per hours" or something like that.


texts: Is summation linear in a passive membrane?

texts:
I am not too sure what it means for summation to be linear? I am running a simulation and as I decrease time for the second EPSP the amplitude decreases. Does summation being linear mean that there is a direct negative linear relationship between delay of onset and amplitude? I also noticed there is no change when I double or triple my conductance value.

I am just not too sure what the relationship is telling me.


texts:
I'm suspicious that it might be crayfish, which I'd think was insane (I still kind of do), if I hadn't found a dead one around  my house earlier this summer.

Is that definitely what it is, or do I have to worry it might be wasps?

I'm located in Michigan.


texts: Why do restriction-modification systems work?

texts:
Some RM systems (restriction-modification systems) are plasmid-borne and are transferred through bacterial conjugation. As you all know, there are two genes in an RM system, the gene that codes for the restriction enzyme that restricts a certain nucleotide sequence and the other that codes for the methyltransferase that methylate the sequence to protect the cell from its own restriction enzymes. If these genes are both being expressed at the same rate after the bacteria receives this plasmid, how is the bacteria's DNA protected from the restriction enzymes for the first few hours of expression if the methyltransferase have not yet methylated the entire host genome yet?

Thank you,

CDB


texts:
I just got out of a lecture on mitosis and this part was incredibly confusing. After searching my textbook it doesn't cover it that well either.

The professor mentioned a NUMA protein that is released after NEBD, and that it helps form more Microtubules. I don't really understand how it does this.

Is it just a protein that sits in the pericentriolar matrix and encourages microtubule nucleation? Or is it a a kinase that deactivates some GAPs that destabilize microtubules?

Also, if you would like, there's also this study question I feel is sort of related: What are two proteins located in the pericentriolar matrix that encourage microtubule nucleation?

I feel like one of them is the y-tubulin ring complex. Would the other be NUMA?

Thanks for reading.


texts: I heard that after injury or repeated damage bone becomes denser, can skin become denser as well?


texts:
I am reading a journal paper and I am looking at the materials and methods section. Regarding the Western blot method in the paper, I have come across the following statement:

Proteins were separated by 4 –12% or 8% SDS-PAGE and electroblotted to
nitrocellulose transfer membrane.

I am not sure what is meant by '4-12% or 8% SDS-PAGE' in the above statement. Do the percentage values refer to the percentage of acrylamide in the gel? Any insights are appreciated.


texts: Do all living humans literally descend from one ape?

texts:
In the opening chapter of Sapiens, Harari writes:

  Just 6 million years ago, a single female ape had two daughters. One became the ancestor of all chimpanzees, the other is our own grandmother.

Is there evidence that this is literally true? There seem to be two ways in which it could fail:

(a) Weak version---there is an individual last universal common ancestor, but it's not an ape: that is, all humans (and chimps) share a single individual creature as an ancestor, but that creature was not an ape. It was some earlier ancestor whose descendants would go on to be apes.

(b) Strong version---there is no individual last universal common ancestor: if tracing the entire history of life on Earth and assuming some "stopping point" where we saw life emerge as (e.g.) from a volcanic vent primordial soup, we would find distinct creatures emerging simultaneously in a population, with similar but distinct genetic code, from one of whom some species (such as humans) evolved, and from another of whom others evolved.

Is there evidence that neither is the case? First, (1) that there is an individual creature, rather than a population of creatures, from whom all life descended. If that is true, then it follows that all humans have an individual as a common ancestor, since you can at worst follow the line of descent back to the primordial individual. And, next, (2) that the last common ancestor of all humans (and chimps) was also an ape, rather than say some other animal.


texts: Can NADP be converted to NADPH using d glucose?

texts: For one of our reaction, we require NADPH enzyme. We have NADP in our stock. Is it possible to convert NADP to NADPH using D-glucose anhydrous and if so please provide me how to go about it?


texts: Does the difference in the height of artificial lighting affects the height of the plants?

texts:
I have some plants living on artificial lighting. I've noticed the following in the following two plants of the same species:

This one was grown with lamps very close to it (~10cm).

This one was grown with lamps far away from it (~1m).

The first one got smaller while the second one is much taller. It seems that at least for some plants, the difference of height in lighting affects the height of the plants/speed of growth/etc. As soon as I changed the first plant to a place with higher light, it seemed to grow (vertically) much faster. If that is true, I guess someone already noticed it. I'd like to read more about it, could you point me to references on this?


texts: What is the so called "hepatic glucose production"

texts: I came across this term in my readings but I do not understand how this works. Can someone direct me to some reference as to what this "hepatic" glucose production is all about?


texts: Relationship between DNA strands and mRNA

texts: Does the sense strand or antisense strand of DNA code for the polypeptide product? I'm confused because I know the antisense strand is the template for mRNA but it has anti codons so I do not know how this would be the coding strand. Ok so what I was confused about is when you are getting the code for the amino acid you can look at the mRNA strand which is the same as the sense strand except uracil replaces thymine, this is why I thought the sense strand could have coded for the amio acid instead of the anti sense strand.(the question I was looking asked if its the antisense or sense strand)


texts: Photosynthesis: Can light directly excite the reaction center instead of going through the antenna complex?

texts:
The reaction centers that I am interested in are P680(photosystem II) and P700 (photosystem I)

Here is what I think:

If pigments such as chlorophyll a and b capture light in the antenna complex, and

if the reaction center contains chlorophyll a,

then the reaction center should be able to directly capture photons and transfer their electron to an electron acceptor.

Or do reaction centers use energy from both the sun and antenna complex?

Also, a side question, I thought chlorophyll a were also efficient at absorbing light in the 400nm to 400nm range, but then why are reaction centers called based on their absorption of 680nm and 700nm light?

Thanks!


texts:
Can a hemorrhage occur after death?

Specifically lung hemorrhages. Can an organ hemorrhage after death and, if so, how long for?


texts: Why is duck fat less saturated than cow fat?

texts: Why does the composition of fat in animals vary?  Is there an evolutionary advantage to producing fat that is less or more saturated?


texts: Identify black insect on Granadilla plant in South Africa

texts:
Planted a granadilla tree 3 weeks ago and these guys appeared on the new growth.
Never seen them before.


texts: Blood urea nitrogen and usage of proteins?

texts:
I have been reading some books and am getting slightly confused. Here is roughly what I have read.

  The greater the blood urea nitrogen the greater the usage of proteins (since blood urea nitrogen is created via the metabolism of proteins).

and

  A positive nitrogen balance (where nitrogen balance $=$ N intake $-$ N loss) indicates a greater usage of proteins.

To me these two seem to be contradictory, if you have greater blood urea nitrogen then surly you will have more nitrogen lost meaning the nitrogen balance would be more negative. So do these two statements contradict and either way please can you explain.


texts: Why is there a structural difference between the bicuspid and tricuspid valve?

texts: There are three cusps in the tricuspid valve and only two in the bicuspid valve? Why is there such a structural difference? Does it have anything to do with that there is oxygenated blood on the left side and deoxygenated on the right?


texts:
I am interested to know if a human body can store protein.

Absolutely for the bodybuilders, does it really matter if they divide their protein consumption during the day or eat all of it in one meal at anytime they want?

Is there any constrain on protein absorption per hour?
What will happen for the extra protein we eat?


texts: I am trying to understand if they are the same as the blood antigens. The books I have tried to read say something about them being the antigens on the surface of the red blood cell.


texts: If chlorophyll or chloroplast is needed for the process of photosynthesis then how do non green plants with no chlorophyll get food


texts:
Probably a basic question, but are all possible dipeptides synthesizable?
For 20 amino acids, there should be in principle 190 dipeptides; do they
all exist or is there chemistry that makes some combinations unstable?
A straight forward generalization would be to ask what percentage of
peptides (or proteins) are synthesizable (in the lab or in cells).


texts: How do schools of fish get enough oxygen?

texts:
Fish get oxygen from the water running over their gills, during which up to ~80% of oxygen is removed from the water. In schools of fish, how do fish swimming behind other fish get enough oxygen in this case? It seems counterintuitive that the volume of unenriched water is repleted with oxygen within the fraction of a second before the fish following behind attempts to gain oxygen from it.
Thanks.


texts: Determine whether aromatics originate from polyketide or shikimate pathway

texts: Is there a way to determine whether an aromatic compound  originates from the polyketide or shikimate pathway by looking at its structure? If so, how?


texts: What is this bug living on the plaster in my home?

texts: It's a small larva looking creature that pops out of a volcanoe-esque hole in the bathroom. SE United States.


texts: DNA methylation and the validity of the definition of epigenetics

texts:
I am currently studying a textbook that presents the following definition of epigenetics:

  Epigenetics is defined as heritable changes in gene expression without changes in the DNA sequence.

The authors then claim the following:

  DNA methylation is a stable and inheritable epigenetic mark. This genetically programmed modification is almost exclusively found on the 5' position of the pyrimidine ring of cytosines (5mC) adjacent to a guanine.

Given these two excerpts, it seems somewhat contradictory to define epigenetics as heritable changes in gene expression without changes in the DNA sequence. After all, the DNA sequence is comprised of nucleotides, and it is these nucleotides that are modified during methylation (for instance, the addition of the methyl group on the 5' position of the pyrimidine ring of cytosines adjacent to a guanine), right? So, is it not technically true that the DNA sequence is changed? Or is what they're saying that, although the nucleotide is changed (such as in DNA methylation), the base pairs are unchanged (I'm unsure if this is true, just hypothesising)?

I would greatly appreciate it if people would please take the time to clarify this.


texts: What kind of spider is this (reddish spider)?

texts:
I just saw this spider on my door and was wondering what kind of spider this is.
information

Country: The Netherlands (Europe)
Color: quite reddish (maybe an idea why this one is reddish?)

pictures


texts: Why cooking make foods , e.g rice, vegetable etc, soft?

texts: My initial guess was it is due to absorption of water during cooking (role of heat is probably to accelerate this process). So to verify this I have left uncooked rice  in water for two days but so far it hasn't softened noticably. May be for sufficient absorption of water for softening I have to leave it longer. Or may be my initial hypothesis is wrong altogether.


texts: What is the difference between these two phenomena in our organism: allergy and immunity? Both cause producing of antibodies which struggle against antigens. Is it true, that allergy always leads to destruction of tissues and organs? If yes, why does destruction take place in case of allergy but not within immunity?


texts: Hebbian theory "fire together" clarification

texts:
Donald Hebb states it as follows:

  "Let us assume that the persistence or repetition of a reverberatory activity (or "trace") tends to induce lasting cellular changes that add to its stability.… When an axon of cell A is near enough to excite a cell B and repeatedly or persistently takes part in firing it, some growth process or metabolic change takes place in one or both cells such that A's efficiency, as one of the cells firing B, is increased."
  Or we can conclude in short: "Neurons that fire together, wire together".

As I understand it, this means that synapses that already exist become stronger between neurons.

Could new synapses form between neighboring neurons that "fire together", but are not necessarily directly connected through an axon?
And if so, what is the mechanism to direct the new synapse formation towards that other neighboring neuron that "fires together"?


texts: How can I label cryotubes in a way that eliminates the problem of legible hand-writing?

texts:
My lab stores biological material (tissue, cells, plasma, serum) in a -130 C, liquid nitrogen freezer. The cryotubes that we use to store a samples are labelled by hand which frequently creates legibility problems.

Its my understanding we can't print out stickers to use as labels because they will degrade in the cold. The solution of putting barcodes on the tubes has been suggested but its undesirable because in addition to the cost and logistic complications; we would have to choose between thawing and refreezing all of our samples to transfer them to new tubes OR live with the nightmare of having both labeling systems in use at the same time; one which humans can read and one which humans cannot.

The ideal situation would be a small, portable machine that can physically label the tubes for us. I'm envisioning:
 - an adjustable clamp to hold the tube in place; ideally with sensors that would infer the shape, size, and position of the area that can be labelled.
 - a very-fine tipped pen attached to a motor that would mimic a printer's line-by-line printing action; this would have to take into account the shape and size of the area that can be labelled
- rollers in the clamp to adjust the available space for labeling
 - a screen/keyboard interface that would display how the label will appear

Does anything like this exist?

Do you have any other suggestions about how to deal with the problem of legible hand-writing on cryotubes?

Please advise if there is a more-appropriate SE site to post this question


texts: Brain wave and motor movement correlation

texts:
I am trying to better understand which brain waves are generated when the motor system (arms, legs, muscles of any kind) are activated.

According to Wikipedia, several types (Beta, Gamma, Mu) appear to be generated when motor movement is present, but it is not clear which muscle groups/movements/characteristics generate which types of waves.

Also, I see the certain waves (Alpha an Mu for instances) appear to have overlapping frequencies. If their frequencies are the same, then what makes them different?


texts: Is urine dirty as soon as it leaves the human body?

texts: Human urine is sterile as long as it is in the human body. But is it dirty after leaving the human body? Could you get sick from it, if you drink it or don't wash your hands, for example?


texts: Human anti animal antibodies issues in blood testing

texts: Do people have to be exposed to animals to get HAMA antibodies? Can these antibodies impact blood tests with false negatives as well as false positives?


texts: Are drugs made bitter artificially to prevent being mistaken for candy?

texts:
All drugs I remember tasting (with the notable exception of Aspirin) have bitter taste. Is the taste due to the active substance, or is a bittering agent added to them, perhaps to prevent overdose?
Take Paracetamol for instance: adult pills taste bitter, while the syrup for babies is sweet without any noticeable bitterness. Or is the dosage simply so low that I couldn't distinguish the drug taste behind all that sugar they put in?


texts: How did ancient human deal with biting insects like mosquitos?

texts:
How did early humans, once hairless, but before clothes and ointments.

I understand that hairlessness was an advantage against parasites but it it seems like a disadvantage antagonistic for mosquitos and such.


texts: Why isn't there any repulsive force between Na+ and K+ disrupting thier roles in transmembrane voltage/ action potentials

texts: Pretty self explanatory question. I have a basic grasp on the "How" and "Why" of Reversal/Action Potential in and between neurons, but this question lingers.


texts: How much time do INS1-E and MIN6 cells need after splitting?

texts:
I am currently doing an experiment on cells to test the internalization of a protein.
Normally, I seeded my cells the day before the incubation. This worked well for Hela, CHL or PANC1 cells. However, when I did the same with INS1-E and MIN6 (both beta-cells) after the incubation and the washing step the majority of the cells were gone. This was better in the control where I did not put in the compound, but still a lot of cells were detached.

Therefore, I wonder if I should seed the INS1-E and MIN6 cells earlier, more like 2-3 days before. Do these cell lines need more time after splitting to attach again?


texts: Why does muscle tissue have relatively constant AMP + ADP + AMP?

texts:
I was going over slides of energy expenditure in muscle cells. It mentions that in muscle tissue, the cell's energy charge ([ATP] / [AMP]) is the principle factor controlling glycolytic activity, and also that glycolysis’ primary role here is to provide ATP for contraction.

However, the slides also mentions that "Keep in mind that [ATP] + [ADP] + [AMP] remains relatively constant in the cell over short time frames" with no further explanation. I was under the impression that ATP was actively consumed in muscle tissue during intense activity (which is why lactic acid builds up in muscles: oxidative phosphorylation can't keep up with your rate of energy expenditure).

Thus, my question is Are my slides wrong? During muscle activity, is there a general lack or constancy of ATP?


texts:
I'm just wondering when I yawned, there are tears coming out from my eyes, which makes me look like I'm crying.

So my question is how does yawning give out tears?


texts: Are some facial features more important than others in human facial recognition?

texts:
I'm often surprised by the human ability to correctly identify other individuals despite significant modifications due to ageing, hairstyle, injury, etc. But, sometimes the addition of a beard and a hat can radically increase the identification error.

I wonder whether all facial regions are equally important when we try to recognise human faces? Do we focus more on some regions than others? I doubt that this is the case, but I'm not certain.

Update:

So far I've read through the following:

1) http://en.wikipedia.org/wiki/Face_perception

2) http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2998394/

So far I haven't found an answer so I decided to try Biology.StackExchange.


texts: How do the chemicals in our skin react with stainless steel?

texts: What acid/chemical in human skin can react with stainless steel to leave a black mark on the skin? Why is it secreted/produced in larger quantities by some people and not by others?


texts:
When a reflex arc occurs the signal from the receptor passes straight to the motor neuron instead of being passed onto the brain.

This is a rather simplistic explanation, I was hoping to make it more detailed. How does the body know when a threshold, heat for example, has been crossed and what mechanism is able to activate the reflex?

Also where does this occur, in the receptor or the spine?


texts: Is the skin of feline jungle predators protected against ants?

texts:
I was watching a video of a jaguar stalking along a riverbank, killing prey, climbing up the muddy bank, then laying in thick brush to eat. My first thought about this is that there must be tons of ants. I've never been to a jungle but on muddy river banks around where I live if you crawled around near the water and on the forest floor in general you'd be sure to get attacked by ants and it would result in hundreds of bites which cause swelling, major discomfort, and perhaps infection.

This seems like it would be a problem for large mammal jungle predators that kill prey in that kind of river bank area and then plop down and eat it. Does the fur make them immune to ant bites, or ants more rare in the jungle than I imagine, or they do get bitten but they just have a high tolerance for pain?


texts: How many cyclic and non-cyclic photo-phosphorylation is required to produce one molecule of glucose?

texts:
In non-cyclic photophosphorylation 1 ATP and 2 $NADPH_2$ molecules are produced.

In cyclic photophosphorylation 2 ATP molecules are produced.

For production of one molecule of Glucose 18 ATP and 12 $NADPH_2$ molecules are reqiured.

According to my understanding,6 turns of cyclic and non-cyclic photophosphorylation is required to produce one molecule of glucose.

Because 6 turns of non cyclic photophosphorylation will produce 12  $NADPH_2$ and 6 ATP molecules.

And cyclic photophosphorylation will produce 12 ATP molecules.

Total=12 $NADPH_2$ and 18 ATP.

I think Iam missing something , Please answer me if I am correct or not.


texts: What are the long term consequences of settling an isolated territory with an extremely limited gene pool?

texts:
I remember reading about a discredited theory - I'm afraid that, despite some frantic Googling, I've been unable to track down a link - which stated that Australia was first settled by a woman, pregnant with a son, who washed up on a beach. It struck me as surprising that such a theory was ever proposed; I know very little about genetics, but it seemed implausible that all Aboriginal Australians, who seem about as physically healthy as any other race, are descended from just a mother and her son. But could just one woman be the progenitor of a healthy nation? And, if not, what is the minimum number of distantly-related individuals required?
As was stated in the answers to a related question: the more immediate consequences of inbreeding are a dramatic rise in inherited diseases, as well as, perhaps, some mild intellectual disabilities. But what are the consequences over several generations? The Pitcairn Islands and Easter Island/Rapa Nui spring to mind when thinking of historical examples of isolated territories with limited gene pools: both seem to have been settled by around two dozen individuals. Did either community experience specific problems over the centuries due to a small gene pool?

The above, obviously, is concerned with our own species, but I'd be very interested to hear about this topic with respect to other species too. I seem to remember, in one of his "Dark Horse" podcasts, Bret Weinstein talked about how a particular species of Hawaiian bat colonised those islands by way of a single pregnant female being blown off course and/or washing up on a beach. Again, is such a thing plausible, and, if so, what would be the long term consquences for the colonisers?


texts:
I spotted this spider in my garden (Northern UK). The body is about 20mm long, and it's made a sizeable (50cm) web on a wall.

There's another semi-identical one on a nearby hedge.

What kind is it?


texts:
I am new to the Gibson assembly, I know how I need my plasmid but main problem is I don't have short tags and linker so I wanted to do Gibson assembly?
5'-TCACTCTCGGCATGGACGAGCTGTACAAGcagcggcagcgaaaccccgggcaccagcgaaagcgcgaccccggaaagcgaaaacctgtactttcagtccgactacaaggaccacgacggtg

Capital letters - my plasmid backbone
Italics - 3xtag
Bold - TEV site

I have plasmid backbone but I dont have 3xtag and TEV site so how can I design the primer so that i can do Gibson assembly to incorporate the sequence?


texts: Is it plausible that eukaryotic organelles like flagella and cilia are the result of endosymbiosis with spirochetes?

texts:
This was a claim by Lynn Margulis explained over at this link.

  The sense organs of vertebrates have modified cilia: The rods and cone
  cells of the eye have cilia, and the balance organ in the inner ear is
  lined with sensory cilia. You tilt your head to one side and little
  calcium carbonate stones in your inner ear hit the cilia.  This has
  been known since shortly after electron microscopy came in. Sensory
  cilia did not come from random mutations. They came by acquiring a
  whole genome of a symbiotic bacterium that could already sense light
  or motion. Specifically, I think it was a spirochete [a
  corkscrew-shaped bacterium] that became the cilium.

And why would our bodies incorporate spirochetes as part of our basic functionality?

  There are many kinds of spirochetes, and if I’m right, some of them
  are ancestors to the cilia in our cells. Spirochete bacteria are
  already optimized for sensitivity to motion, light, and chemicals… If
  I’m right, the whole system—called the cytoskeletal system—came from
  the incorporation of ancestral spirochetes.


texts: Advanced Higher Biology 2017 - EPT Index

texts:
I was recently completing a biology past paper the Scottish SQA 2017 Advanced Higher Biology Qualifications. The question is as follows:

To solve this, I did:

EPT Index = 100*(striped stonefly + net spinning caddisfly + flathead mayfly)/(total number of taxa) = 100*(6+6+3)/(44)=34.09%

So, I answered C, however, the answer is B. What mistake have I made?


texts: What are the main technical differences between accurately calling somatic point mutations vs copy number variation (CNV) in exome data? Side note: would you need other -omic data to accurately infer CNV (exome data isn't enough)?


texts:
What is Meriva Phytosome Curcumin other than being a food supplement?

Is it a plant? A type of plant extract?

I googled it but still couldn't figure out exactly what it is.

The reason I'm asking is because I came across the following list in a site selling vitamins and other food supplements:

Meriva Phytosome Curcumin
Turmeric (Curcumin)
Turmeric Formulas

It wasn't clear to me if Meriva Phytosome Curcumin is a specific kind of curcumin since it seems to be sold under a few different brands.


texts: How does the human ear guess the direction of the source?

texts:
Suppose a sound is produced behind you. You can easily tell that the sound came from behind.

Our ear lobes face towards the front and hence traps the sound waves which come from the front. Yet, we can detect   that the sound came from behind.

How does the ear/brain manage to identify the sources of sound accurately?


texts: Why does Taq polymerase add 3' adenine overhangs?

texts: Is there a mechanism for the preference of Taq polymerase to add a non-templated 3' adenine (overhang) instead of other bases?


texts: Explanation of universal model of energy flow

texts:
I am trying to understand the Universal model of energy flow by Odum.

In this linked diagram I is the input energy(the amount of energy present in the food consumed by this tropic level, say its, the 2nd tropic level, the herbivores), part of this food is excreted as undigested food (the NU) , the rest is digested, absorbed and assimilated reaching the cells and then the energy accumulated at cellular level is called the assimilated energy (A). Now part of A is utilised to make ATPs that are being used to fuel the metabolisms occurring in the organisms which is represented by R and the rest is available to the next tropic level(?) as P ?

Then what makes the standing biomass? The organisms the are not eaten up?

Besides I don't understand the Energy Storage part. What physiological process corresponds to this?


texts: How and why are cells irradiated in human-rodent hybrid cell biology?

texts: When human-rodent hybrids are made the amount of human chromosome in the hybrid can be reduced by irradiation. Why and how exactly is this irradiation step performed?


texts: What is the reaction mechanism of dopamine hydroxylase converting dopamine to norepinephrine?

texts:
The reaction is basically shown below. Dopamine hydroxylase is an enzyme, so I'm not sure if we can have a theory based on organic chemistry. On the other hand, maybe there is a theory that involves structural biology?

Evolutionarily speaking - the enzyme has evolved to add OH to the beta-carbon rather than somewhere else. I'm really wondering what in the enzyme's shape makes the OH added to the beta carbon, rather than somewhere else. In other words, what is the structural mechanism behind substrate specificity?


texts: Are MHC Proteins the Most Polymorphic Human Proteins Known?

texts:
There is a paragraph titled "MHC Proteins Are the Most Polymorphic Human Proteins Known" in the "Molecular Biology of the Cell" by Alberts et al. 6th ed. 2014.

But someone has recently told me that it is not the case making an example of a set of genes helping to identify persons in forensic medicine. (I didn't remember the genes.) Is it true?

Are MHC proteins the most polymorphic human proteins known?


texts:
Found in Pennsylvania, Philadelphia County

This is intentionally planted, not sure if it is indigenous to this region. Thank you for your expertise!


texts: Does Yerba Mate contain Beta carbolines like harman and norharman?

texts: I know that this is true of (roasted) coffee but haven't been able to find any reliable information about mate in its smoked or steamed state.  Thank you.


texts: Cleaning out Agar from Autoclave Reservoir

texts:
I have a Tuttnauer EZ10 autoclave where the previous user poured m-Endo Agar into the reservoir. Using vinegar, we've been able to remove most of it, but there is a thin film of purple residue coating the interior walls. To get the autoclave safely working again, would you recommend I 1) pour water in and do a steam cycle, or 2) buy the Tuttnauer Chamber Brite and use it?

P.S. I can't make an agar, autoclave, reservoir, maintenance, or cleaning tag, so would someone please make those too?

Thanks in Advance!


texts: Does sociality evolved before or after the ability of motility?

texts:
According to book Life Ascending: The Ten Great Inventions o Evolution.
(Lane, N.;2010),

  Motility has indeed transformed life on earth in ways that are not
  immediately apparent, from the complexity of ecosystems.

As I understand it, when animals had begun to actively use their bodies to locate resources and thus left the sedentary way of life the amount of information they received has increased exponentially. It induced the rapid evolution of additional physiological, morphological and behavioural adaptations such as specialized brain regions enabling spatial memory, vision or cognition.

Was sociality also additional adaption induced by motility?
Is sociality as a life strategy present only in mobile animal species, or they exist also a social sedentary organisms?

Working definition of sociality: Forming of animal group where information transfer enable cooperation among individuals.


texts: Are vacuum centrifuges the same as normal centrifuges?

texts:
I came across a method that used a vacuum centrifuge:

Carvalho et al. 2012. The diversity, antimicrobial and anticancer activity of endophytic fungi associated with the medicinal plant Stryphnodendron adstringens (Mart.) Coville (Fabaceae) from the Brazilian savannah. Symbiosis 57(2):95-107

  Five-millimetre-diameter plugs of each filamentous endophytic fungus were inoculated into the centres of Petri dishes (60 mm diameter, 20 ml PDA). The plates were incubated at 25±2 °C for 15 days. The culture materials from each Petri dish were cut and transferred to 50-ml vial tubes containing 35 ml of ethanol (PA, ≥99.8 %, Vetec, Brazil). After 48 h at 10°C, the organic phase was decanted and the solvent was removed under a vacuum centrifuge at 35°C

I couldn't find information online as to whether a vacuum centrifuge is the same as a normal centrifuge. Is there a difference?


texts: Are there any theories why such an imbalance in chirality of molluscs?

texts: Most gastropods exhibit sinistral  (right hand) winding of their shells. But very few species are anti sinistral. Have there been any theories as to why such a great difference?


texts: Can you please identify this mosquito-like insect?

texts:
I've seen these insects before (here in Cambridge, UK) and thought that they were probably mosquitoes, but they don't make the annoying noise that mosquitoes do (they fly similarly, but silently):

I also noticed that they are perhaps slightly larger than mosquitoes (maybe 12mm long) and don't have the long mouth which mosquitoes use to sting you.
Sorry for the poor photos, I don't have a camera with a macro lens anymore, and it's night-time. It's casting a strong shadow as you can see in the second photo.


texts: How to calculate or know by experiment the entropy of enzymes or protein?

texts: How do you calculate or experimentally determine the entropy of enzymes or protein?  In particular, I am interested in Boltzmann and conformational entropy, and Gibbs free energy.  Any references are welcome.


texts: Identifying flying insect from southern Poland / Upper Silesia area

texts:
Yesterday evening, I spotted this quite huge insect at my home in southern Poland (the exact location of the place). Unfortunately, I have only a very low quality pictures available at the moment:

Some details:

found in southern Poland / eastern Europe,
about 3 cm long,
quite fat (if I may say so),
seems to have 4 pairs / 8 legs in total,
airborne / able to fly (though quite slowly).

The quite huge (as per typical insect in Poland) size of this species was kind of surprise for me, but its behavior was even more surprising to me:

As pictured, it was able / willing to rest (copulate?) one on another even in groups of three (I failed to picture this), remaining still / not moving at all even for as long as half of hour.
After such resting / copulation ended or was interrupted the species on top was thrown off, falling down to the windowsill beneath.
It was then lying there up-side-down on its back, again remaining still and not moving at all even for 10-15 minutes.
Then it was kind of waking up from some kind of stasis, turning over walking a little bit around the windowsill.
Then it was flying up, flying around a little bit.
Finally, it was trying to rest / copulate with the species still on my window's mosquito net (or with the couple being there).

And then, the whole cycle was repeating until (late evening) only one species remained on mosquito net, which was also gone late in the night (not found the following morning).


texts: Definition of nucleotide-associated proteins and RNA-polymerase associated proteins

texts:
Nucleotide-associated proteins and RNA-polymerase associated proteins, I found those two terms in an article but I didn't understand what they mean exactly, is there any relation between those terms and DNA-binding proteins ?

The article : DNA supercoiling-a global transcriptional regulator for enterobacterial growth?


texts:
The Colorado potato beetle is best known for being a potato pest. However, I've just learned that it originates from Northern America and the potato itself comes from South America.

So the question is, what did potato beetles eat before they were introduced to potatoes?


texts: What's the evidence against SARS-CoV-2 being engineered by humans?

texts:
A couple of colleagues suggested in a discussion that the virus that causes COVID-19 appears to be made by humans, since nature could not have produced such an efficient virus — that spreads so fast and whose patients are contagious quite some time before showing signs of infection.

Since my knowledge of biology is very limited, my only counterargument for such a conspiracy theory was along the following lines:

there is a consensus that the most probable source of the first infection was in an animal market in China.
since that animal market was actually composed of a plethora of animals belonging to various species (mixed with humans), a virus had a bigger chance of evolving a mutation that might infect an individual from another species (a thing that is way less unlikely in the wild since many of those animals do not sit close to each others or next to humans).

Clearly, I have made a little story that might be quite far away from how SARS-CoV-2 infected humans, so I am interested in a scientific arguments to support my cause.

Question: What are the main scientific arguments that can be used to debunk COVID-19 being engineered by humans?

Answers that also include explanations more accessible to laymen are greatly welcomed.


texts:
Please help identify this insect - genus, species and anything interesting about it. Also - please outline your general methodology for identifying such insects

Note, this is posted separately due to comments in this other thread.


texts: How do PER/CRY complexes accumulate in the cytoplasm?

texts:
The Period/Cryptochrome (PER/CRY) complex is a heterodimer that transcriptionally regulates circadian rhythm. When it is phosphorylated, it is transported to the nucleus and it inhibits a transcription factor that regulates the synthesis of its own subunits (negative feedback).

Research on the circadian molecular clock speaks of an accumulation of PER/CRY complex in the cytoplasm during the day phase (see review The circadian clock: pacemaker and tumour suppressor, Fu and Lee, 2003). Why does this complex not move to nucleus during the day? In other words how is the phosphorylation-dephosphorylation switch controlled?


texts: VCF files - examples for haploid organisms

texts: I am trying to self-learn some aspects of bioinformatics (coming from a stats background), and i am trying to find / download some VCF files for haploid organisms as an input to some statistical analyses. I have seen a few sites where one can download example VCF files for human populations, but there are any sites where i can download some example haploid VCF files from e.g. bacteria as well? I have tried to look at http://bacteria.ensembl.org/info/website/ftp/index.html - but i was not successful yet. That said, as a newbie, i might very much be looking in the wrong location.


texts: Why severely increased Ligand (eg Hormones) concentration downregulates the Receptor?

texts:
As an example continuous high blood level of GnRH in humans causes a suppression of LH and FSH. This is due to the fact that increased GnRH downregulates GnRH-Receptors . My question is how this is done and why? What are the probable molecular mechanisms underlying this effect?

Kumar P, Sharma A. Gonadotropin-releasing hormone analogs:
Understanding advantages and limitations. J Hum Reprod Sci.
2014;7(3):170-174. doi:10.4103/0974-1208.142476
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4229791/


texts:
Most animals can digest the cellulose in grass because of the anaerobic bacteria called Fibrobacter succinogenes living in their rumen (gut). The bacteria produces the enzyme cellulase and is therefore able to break down the β-Glucans(1,4) glycosidic bond in the cellulose. Animals like cows and giraffes grow up to be very large simply on a diet of grass!

Is there a way for humans to ingest the Fibrobacter succinogenes bacteria and be able to digest cellulose?


texts: meaning of "initial gene constructions" vs. "under the control of plant promoters" in an article on GM plants

texts:
From "Risks from GMOs due to Horizontal Gene Transfer", by Paul Keese:

  Antibiotic resistance genes have been introduced to GM plants either as part of the bacterial cloning vectors used for the initial gene constructions or under the control of plant promoters to select for successfully modified cells. The concern is that the presence of antibiotic resistance genes in GM plants could provide a reservoir for the appearance of new drug resistant bacteria through HGT from plants to pathogenic bacteria.

I'm afraid I don't understand the "either ... or" contrast here. As I understand, antibiotic resistance genes are routinely introduced into GM plants with the sole goal: to check what cells have underwent transformation (got the neccessary foreign genes in their genome) and what have not.

I would be grateful to learn what are "initial gene constructions" here, and how does the method using "the control of plant promoters" differ from the first method. Is the purpose of introducing antibiotic resistance genes similar in both cases - to check what cells have underwent transformation? Sorry if the questions are too stupid. Please direct me to relevant Wikipedia pages or articles.


texts: How well can humans detect vitamin-richness?

texts: Humans do prefer fatty, sweet/starchy and salty. And fatty foods are rich in vitamins. How well can humans detect vitamin content apart from fattiness of food? Can humans choose the vitamin-richer of otherwise identical peanut butter, cheese or chicken leg?


texts: Question regarding when it's a homoplasy in a phylogenetic tree

texts: If you have 2 organisms that both come directly from the same common ancestor on a phylogenetic tree, and that common ancestor does not have trait "x", is it possible for both of its direct descendants to develop that trait "x" independently, and would that be an example of a homoplasy?


texts:
I have this succulent at home and was wondering about the following questions:

What kind of succulent is this?
What will the leaf grow into?
Will there appear more leafs or just a single one?


texts: Some foods leave an acidic effect on the body such as meat and dairy, while others leave an alkaline effect, like vegetables. However, are these effects significant enough to greatly alter the blood pH that seems to be strictly monitored by the kidneys, which keep it around 7.4?


texts:
I think it's a moth and need further identification like scientific name, order and family.

The picture was taken on May 30/2016 in my university laboratory window in South Korea. At that time there were so many moths on this building. The temperature was also high and it was also daytime around lunch time. What I want to ask related to flying time is do moths fly at daytime? as far as I know moths are nocturnal. Please clarify this too if this insect species is moth.


texts:
I have 10 molecules in VMD main screen and I was wondering if there is a script command to change what molecule is the top.

For example, molecule ID 9 is the top. But I want to change the top to 1, without using mouse.

Thanks!


texts: Why would hawk moths evolve long tongues for Darwin's Star Orchid when there are other flowers around?

texts:
Why would hawk moth evolve long tongues for Darwin's Star Orchid when there are other flowers around? Also isn't it counter productive for some flower to evolve a long nectar tube as this would shift the pollinators to other plants?
This coevolution makes sense if the only source of food for the moth is this star orchid and the only pollinator for the flower is the hawk moth. But if we consider other species to also exist in the picture, this coevolution seems counterproductive to me. For example most flower evolve mechanisms to attract pollinators as their is competition for pollinators as well.


texts: Can mRNA vaccine have flaws and generate the wrong spike protein?

texts:
Someone asked me if SARS-COV2 mRNA vaccine could create the wrong spike protein and have a negative effect on our immune system. Since I know too little about biology I couldn't answer that and started doing some deeper research than I did before on mRNA. But I can't seem to find anything to answer my question (it most probably is because I lack the knowledge in this field).
So here are the two main questions of this problem:

When created, can the mRNA vaccine have flaws and when injected generate a different spike protein than the SARS-COV2 one ?
If so can the spike protein be harmful to our system in any way ?

I am sorry for any term not correct in this context.


texts: How straightforward is in vitro compartmentalization?

texts: in vitro compartmentalization (IVC) is one of those technologies that everyone knows about, talks about, but never actual does due to the rather technical difficulties in setting the system up. I was wonder if anyone not named Tawfik, Griffiths or someone who did a post-doc with them have been successful in making IVC work? Details in how stable emulsions and a homogeneous mixture of cell-free components in the droplet are made would be wonderful.


texts: Why do red blood cells contain haemoglobin and not myoglobin?

texts: So I am reading about muscles and I come across myoglobin. It has a much higher affinity for oxygen than haemoglobin. So why have animals evolved to have haemoglobin in red blood cells, rather than myoglobin, which would be much more advantageous?


texts: What are the on-rate and off-rate constants for 5-HT1 receptors binding 5-HT?

texts:
The class of 5-HT1 receptors binds serotonin (5-HT) reversibly (Wikipedia). I'm interested in the on-rate and off-rate constants $k_{\text{on}}$ and $k_{\text{off}}$ of this process.

So my question is: Have these constants already been determined experimentally for any member of the 5-HT1 receptor family, and, if so, what where the values observed?

Edit: Since this question didn't get much attention yet: Instead of the on-rate and off-rate, maybe the dissociaton constant/binding constant of the binding process is known?


texts: do tumour cells begin with abnormal characteristics?

texts: At what point in the cell cycle do cells start to become tumorous? Do they have abnormal characteristics to begin with; if so what are they?


texts: How does phloem give priority for sugar transport to certain fruits?

texts:
I have a question from curiosity as I am totally new to agriculture:
When phloem transport sugars and proteins in plants from the leaves to the fruits, do the fruits that are nearer more leaves actively producing sugar (those more exposed to light) get higher concentration of sugars compared to those not near leaves or leaves or those that are predominantly shaded?
I know in some plants the upper fruits may take priority for sugar intake because those leaves are most exposed to light and that level attracts pollen more, but further down how do phloem give priority to which fruits get more sugar since phloem transport in every direction?  Is there any reasoning why in some plants there is difference in fruit size even when both are equally exposed to light, other fruit don't grow at all?


texts: Is this mammalian embryo blastocyst, gastrula or only phase between them?

texts:
The picture shows the formation of early blastocyst and late blastocyst.
The middle embryo has embryoblast.
My professor says that blastocyst in general has embryoblast and trophoblast.

Embryoblast is the inner cell mass but the thing has none of it.
The last embryo does not seem to have inner cell mass anymore.

Is the last embryo in the picture anymore blastocyst?

The given thing seems to be "the single layered blastocyst that will give rise to gastrula", Wikipedia Gastrulation. The given stage seems to last very short time. It probably should be called phase between blastocyst and gastrula so that the thing is not blastocyst and not gastrula.

What is the right name for the given thing in mammalians?


texts: If someone with "XO" is one of the identical twins with the other twin as male, then what would the sex chromosome of the other twin be?

texts:
A more complete question: If someone with sex chromosome of XO is one of the monozygotic twins with the other twin as phenotypically male, then what would the sex chromosome of the other twin be?

I had heard that both XXY and XY is possible. Is it true?


texts: What does the term "relay competent" mean?

texts:
I was reading the article of Dallon & Othmer (2010) which deals with cell aggregation in Dictyostelium discoideum. In the introduction of the paper it is said that cells becomes "relay competent". I googled for the term but could not find a good explanation for it.

  After a period of starvation they become chemotactically sensitive to cyclic adenosine 3 , 5- monophosphate (cAMP), as well as relay competent.

Can someone help me understand this term?


texts: Can you freeze an ATP assay sample for later use?

texts:
I am going to use adult Drosophila to do an ATP assay (ATP determination kit A22066). The most convenient for me is to freeze the samples and perform the experiment later.

However, the protocol provided by the kit producer keeps saying the assay is extremely sensitive, so I'm not sure if it's okay to keep the homogenized samples under -80°C for a short period of time.


texts: SE Brazil Atlantic rainforest Oct 2017. I'm assuming this is an early stage of an insect. It was crawling around a tree in the moss and was about 6-7mm.


texts:
I found it hard to get numbers on global primary production, but apparently it's somewhere around 50-60 $Gt / year$ for carbon content in the terrestrial production, and a similar figure for the oceans. Global oil and coal extraction together are around 10 $Gt/year$, only a part of which is pure carbon (iirc, around 80%). Since carbon in the air actually increases, does that mean that most or all of the carbon fixed in Net Primary Productivity go back into the atmosphere through consumption and destruction of the biomass?

I was assuming that the biosphere in total was fixing more carbon that it emitted, and that the surplus was what turned into oil and coal. But with these figures it looks a lot more like a full circle that nets to zero input / output. Which is true, or is that unknown?


texts: It's not explained on the wikipedia page. So if, apparently, 'H' is not relevant, why is it part of the name? And if it is relevant, why is it not explained?


texts: How Do Adherent Cells In Culture Attach To A Plastic Dish?

texts: I am particularly interested in MC3T3-E1 cells (mouse fibroblasts), which are adherent cells. Are hemidesmosomes involved in anchoring the cells to the plastic dish? What (if any) other molecules are involved? What happens at the molecular level?


texts:
What would happen if we inject a chloroplast organelle into an animal cell?

Will the animal cell destroy it? Or is it possible that the chloroplast will somehow survive, and even replicate? Could there be photosynthesis in such a cell, or will some of the necessary mechanisms be missing?


texts: Why they have much more antibiotics than plants for instance?


texts: Do large animals experience a meaningful delay when moving their most distant appendages?

texts:
According to the Physics Factbook, nerve impulses travel at speeds anywhere from 1 meter per second up to around 100 meters per second. Blue whales reach up to around 30 meters long.

For a full-size blue whale, this means that a nerve impulse to move the tail muscles could take from 0.3 seconds to 30 seconds to reach the tail. While I'd imagine factors such as myelination and other adaptations function to keep this closer to the 0.3 second measure above, this is still a best case scenario, and would certainly be a noticeable delay were it a human being.

Do large organisms experience meaningful delays when moving their most distant appendages?


texts: Does introgression require interspecific hybrids to be fertile? How is this possible?

texts:
Wikipedia says that Introgression, also known as introgressive hybridization, in genetics is the movement of a gene (gene flow) from one species into the gene pool of another by the repeated backcrossing of an interspecific hybrid with one of its parent species.

Does this mean that the interspecific hybrid is fertile? But is it possible, that an interspecific hybrid is fertile?


texts: Diffusion of Hypotonic solution into solution with glucose and starch

texts:
Cell walls are selectively permeable to ions and organic molecules. Sometimes the selectivity is passive and a reflection of the physical laws governing diffusion. We can do simple experiments that strengthen intuition about transport across biological membranes. The following homework question concerns a situation which tests understanding of the basic ideas of osmosis and diffusion generally.

  A bag made of a flexible semipermeable membrane is filled with a 10% glucose and 5% starch solution. This bag is permeable to water and glucose but NOT to starch. The bag is suspended in a a beaker containing a 10% glucose solution. In 30 minutes the bag can be expected to

(A) swell
(B) shrink slightly
(C) collapse entirely
(D) become impermeable to glucose
(E) remain the same

Since the bag is impermeable to starch, I know that the solution in the bag isn't going to diffuse outside so it won't shrink, but would water from outside flood into the bag to try to dilute the starch concentration to the point that it's isotonic? Or am I not understanding some fundamental principle of diffusion?


texts: Why is cisplatin a very potent antineoplastic for testicular cancer, but not necessarily for other cancers?

texts:
Cisplatin (structure below) is a platinum-based chemotherapeutic agent which is very effective in the treatment of some cancers. Its introduction was responsible for improving the cure rate for testicular cancer from 10% to 85% according to the wikipedia page on cisplatin.

However, it is not very effective for other types of cancers; interestingly, ovarian cancer does not respond well to it (Siddick, 2003).

Does someone know why cisplatin is so specific to testicular cancer? I haven't found any sources explaining this.


texts: Why did Henrietta Lacks die when her cells didn't die? As I understand it only the cells from her cervix were immortal so perhaps the cervical cancer took her life and the cells never died.


texts: Can inverted microscope also be phase contrast microscope?

texts:
I've read somewhere that inverted microscope also allows phase contrast microscopy. Is that true? Do all inverted microscope have this ability? Do they have any other functions?

Many thanks in advance.


texts: Do intestinal flora have the same DNA as their host?

texts:
Please bear with me, this is not my professional field and I might be mixing things up. In an explanation why seeds won't start growing in one's intestines, the explanation given was that foreign bodies are detected by the DNA they carry and get attacked and digested, separating all strands of amino acids so they can be reused by the host and no DNA mixture can occur.

I also heard that the immune system uses the same technique to detect intruders (and subsequently attack donor-organs).

I was wondering, when a baby gets weaned (starts eating regular food), where do these fauna come from? Does the baby produce them, or are they provided in the food and survive the defense system?