texts: Maximum biologically possible age for a human being?

texts: Today, most of people die because of some kind of illness that we do not yet have a cure for. However, if that was not the case, how long can human body possibly live for? Is there a theoretical maximum at which our brain will simply refuse to function due to age alone, or can we remain conscious forever if we could simply swap our brains into new bodies without any risk?


texts: Similarity between the human genome and archea genome in deep sea hydrothermal vents?

texts:
I'm trying to find some reference that shows what percentage of the human genome is similar to some organism from the domain Archea that lives  near or on deep sea hydrothermal vents.

Can someone points me out in the right direction?


texts: Relationship between blood pressure time series and ventricular dynamics of the heart

texts:
The answer to this question is probably very straightforward, but I have actually had some difficulty finding an explicit answer online.
To what extent does the oscillatory pattern of arterial blood pressure (over small increments in time) mirror the oscillatory pattern of heart beat. For simplicity, imagine my heart beat signal is a binary signal where 0 means blood is not being ejected and 1 means blood is being ejected into circulation.
Said differently, if I detect a transient (where the interval of time is less than one second) increase in arterial pressure (e.g. a local peak), can I always accurately map that event to the "causal" contraction of the ventricles during blood ejection?
Similarly, can I use an arterial blood pressure time series to accurately recreate the binary signal of the heart beat? (Though, perhaps there will be a slight time shift due to the propagation speed of a pressure wave).
To provide another silly example: if my arterial pressure time series has 60 peaks (and corresponding "separating troughs"), can I confidently assert that the heart beat 60 times?


texts:
A fisherman from Hawaii wrote the following:

  This Fat juicy worm lives inside of every Wahoo that I catch. Inside
  the stomach. Right at the junction to the intestines. Sometimes there
  are two.

What is this parasite?


texts: What makes drosophila eyes red? and is it stable?

texts:
I have Drosophila melanogaster which I am doing an eye pigmentation assay on in the future. To do this I will dissolve the heads, 10 of them removed from frozen whole flies, in acidified ethanol for at least 48 hours (in the dark at 25 degrees) and then measure the colour of the liquid using a nanodrop. Specifically, this measures how well the liquid reflects red light, quantifying how much red pigment is in there.

I would like to know what causes the red colour in the eye and if leaving it dissolving for extended periods of time will (or is likely to) result in changes of what I measure? (ie is the material causing the redness in the eye susceptible to deterioration, which would change the colour of the liquid it is dissolving in over time)

Have any methods type papers tested this by comparing those dissolved for longer periods to those over shorter periods?


texts: Found in a doorway in eastern Tennessee. With its legs fully extended, it's about the size of a quarter.


texts: These were found in a park in Pittsburgh, PA. From a distance they looked almost like plums, but they're actually hollow, paper-like covers that contain a hard pea-sized seed.


texts:
Why did Darwin say "the misfortune to undertake"?

"Every naturalist who has had the misfortune to undertake the description of a group of highly varying organisms, has encountered cases (I speak after experience) precisely like that of man; and if of a cautious disposition, he will end by uniting all the forms which graduate into each other, under a single species; for he will say to himself that he has no right to give names to objects which he cannot define."

One reason, is that he was challenged with a difficult task.

Another is that he is unhappy because he could not name more than one species and had to say they are all one species because they graduate into each other.


texts:
I read on https://en.wikipedia.org/w/index.php?title=Gluteal_muscles&oldid=876760828#Clinical_significance:

  Sitting for long periods can lead to the gluteal muscles atrophying through constant pressure and disuse.

However, the statement isn't supported by any reference. Does constant pressure cause muscle atrophy, and if so, why?

I tried to find some references stating that constant pressure causes muscle atrophy, but I haven't found any so far. The following information sources don't list constant pressure as a cause of on muscle atrophy:

https://en.wikipedia.org/w/index.php?title=Muscle_atrophy&oldid=884590568
https://vet.uga.edu/ivcvm/courses/VPAT5200/02_injury/atrophy/atrophy01b.htm  (mirror)


texts:
There are some cell dyes available for stianing cells intracellularly / membrane. I am aware of other channels (CFSE \ PKH26). But I want to stain cells for flow cytometry with a 'red' dye.
I have looked at a few options from Thermo but did not find sufficient data on either.

Specifically I am planning to stain a single cell population with two different dyes, treat each stained population somewhat different in between, and then culture them together and distinguish read-outs later. Antibody-staining for a surface marker would be possible with Fab fragments (the antibodies itself may interfere with cell activation during culturing). Therefore I would rather use a red-spectrum dye like CFSE or PKH26 as this may be cheaper and possible for secondary use with other cell lines.

I have multiple cytometers available and the specific emittance doesn't matter as we can pick what is generally possible (LSR/Fortessa).

Thus, I am looking for a dye with emittance in the red fluorescence spectrum which has staining protocols available that can be adapted for my purposes.

Is anybody willing to share their experiences?

Edit

Clarified that I needed a 'no-antibody-staining'
Clarified question with regard to biological question and FACS


texts: Skin Colour in "Northern" Regions of The earth

texts:
Question: Netflix has recently produced a two-part miniseries, The Evolution of US, that examines the evolution of "man". The topic of of human skin colour was covered and it was stated that 'lighter skin pigmentation was a preferred natural selection for early humans living in the "northern" regions'. The idea being that lighter skin could "absorb" sun-rays; which apparently is necessary for activating vitamin-D. Is this a true statement ? And where might I find good sources of literature to read on this topic ?

Now this particular series does not define "northern" and to be fair neither was the term "lighter skin" . My motivation in asking the question is driven by my own travels in far eastern Russia, Mongolia, Alaska, and parts of Peru and Ecuador. In each of those locations I observed numerous groups of indigenous people with dark brown skin and pitch black straight hair; which seems to contradict the statement in the series.


texts: Why is Somatic Cell Nuclear Transfer (SCNT) less effective for interspecies?

texts:
Somatic Cell Nuclear Transfer (SCNT), a process for replacing the nucleus of an egg cell with a nucleus containing genetic information of a different animal, seems to be very useful for cloning and species preservation.
It seems that SCNT where both nuclei come from the same species is much more effective/successful than interspecies (iSCNT) where each nuclei came from animals of different species. Why is that? Is it because there's different mitochondrial DNA? What other factors could potentially make iSCNT less viable than SCNT?


texts: Which Papaya (Lechosa) plant (male or female) bears fruit?

texts: I will be planting Papaya fruit seeds and I understand that there is a female and a male plant, so how can one distinguish which are the ones that will bear fruit and which I should just rip up by its roots as I have limited planting space?


texts: How Mitochondria differs from Prokaryotes(probably regarding energy production)?

texts:
In other words, what evolutionary advantage is offered by mitochondria to eukaryotes(probably regarding energy production), which prokaryotes themselves cannot evolve or do?(here I am assuming that mitochondria evolved from prokaryotes)

I seemingly found some answers in the below article. Will love to hear the opinion of others regarding the same.

http://blogs.discovermagazine.com/notrocketscience/2010/10/20/the-origin-of-complex-life-it-was-all-about-energy/#.WYXsH4h97b0


texts: Can Stem-loop RT primer bind to the position inside mRNA?

texts:
I knew that Stem-loop RT primers bind to the 3' portion of miRNA molecules and then reverse transcriptase to cDNA. But what about mRNA, can it:

bind to the 3' portion of mRNA and then reverse?
bind to the position inside mRNA and then reverse?

Thank you guys.


texts: What influences the timing of human bowel movements in the morning?

texts:
I'm trying to understand if the timing of human bowel movements in the morning is associated with the circadian rhythm, and can thus be used to make predictions about the circadian rhythm.

What influences the timing of bowel movements? Is it the timing of meals, caffeine intake or is it a biologically programmed time?

Thank you!


texts: Techniques to find out which species are endangered

texts:
Most countries have a list of endangered species and international organisations too issue such lists of vulnerable and endangered species.
What mathematical or statistical models are those estimates based on?
Regardless of which techniques the lists use, what are some of the most popular mathematical models to find out whether a certain species is endangered or vulnerable given the population and/or other environmental data in the academic literature? What is the state of the art currently?
Especially, if I want to learn the models at an intermediate and then advanced level (I already have training as an Economics student on mathematical and econometric modelling), what are some books/ other sources you would recommend?


texts: How and when did a dedicated immune system evolve?

texts:
I have recently been doing a lot of research into the interplay between the innate and adaptive immune systems in humans, and mammalian laboratory models. This has led to my reading some interesting information on the immune response in insects;

  Insects have a highly efficient immune system.  In response to a bacterial attack, their fat body (the equivalent of the liver in mammals) synthesizes a whole range of peptides with an antibacterial and antifungal effect.

This fascinated me, as the clear inference is that there are no ‘dedicated’ immune cells, but that adipose tissue has far more diverse functions that I had realized.

I have done a little more reading, and also looked at plant immune systems, which seems far more analogous to those in insects than mammals;

  Plants, unlike mammals, lack mobile defender cells and a somatic adaptive immune system. Instead, they rely on the innate immunity of each cell and on systemic signals emanating from infection sites.
  (Jones, 2006)

My questions relates to the need of an adaptive immune response in mammals. The immune systems in insects and plants - a more 'systemic' immunity due to the lack of dedicated/mobile immune cells - seems much simpler.

Given that evolution works incrementally (there are no 'jumps' - for instance, going from a non-dedicated immune system, to a dedicated immune system), I would hypothesise that organisms less distantly related to insects and plants may have tissues with duel functions (similar to insects?), but that specialize further as immune cells until gradually (down the evolutionary tree) a complex and specific immune system emerges. (This is complicated by the fact that our immune systems do have multiple roles - e.g. tissue remodelling, but I wasn't going to go into that here. Feel free in your answers if it is necessary!).

My overall curiosity can be summarized as 2 questions;

What are the possible reasons why a dedicated and immensely complex immune system evolved in some lineages of organism?
Is there any evidence of 'half-way' organisms, and about what ecological time-frame might the dedicated immune system have developed?


texts: Do the genes encoded by the nucleus for mitochondrial proteins have introns?

texts: Mitochondria are believed to have transferred much of their genome to the nucleus. I know that mitochondrial protein-coding genes lack introns, but is this true for mitochondrial genes encoded by the nucleus as well?


texts: Can controlled dose of Codeine improve brain's functionality?

texts:
What I know so far about drugs (codeine, heroin, etc) is, the first time you take them you will feel better, think sharper, and act better, just like a supercharged engine. But as this goes on a regular basis, it will stop being efficient and causes addiction.

So what I can understand of this, is that our brain can function better but for some unknown reason (to me) it doesn't. However its functionality increases for a period of time after you take a dose of these drugs.

Now I have a few questions about this:

If our brain can function faster than normal, then why it demands additional drugs to do so?
Can we inject a controlled dose to brain (not by needle to the brain obviously, I mean pills, tablets, etc) of these drugs to keep the brains functionality at a higher rate?
When a drug actually charges our brain, is it taking any damage? The same way you overclock a CPU and it might cause damage to it over the time.

PS: I'm asking this on Biology instead of Health since I'm talking about brain's behavior about addiction, not just to confirm whether or not i can use drugs on a regular basis.


texts: Cats, Dogs and Bears - how are they related?

texts:
What is the ancestral relationship between cats, dogs and bears?

I presume they are more closely related to one another than other paraphyletic clades of mammal.

Which came first?
What did their common ancestors look like?
What are their geographical origins?


texts:
In my textbook, the definition of an antigen is written as follows:

Antigen:  A substance that the body recognises as foreign and that can evoke an immune response

The following image also confused me as it states that, for instance, a person with type A  blood has A-antigens

However, would this statement, and image, not be stating that the antigens found on the surface of our blood cells are foreign? Which would imply that our antibodies attack our own blood which is not what occurs?

Or are the substances found on the surface of blood cells (A or/and B antigens, no antigens) only recognised as antigens when they correspond with the antibodies in the body?

In other words, if I am blood type A, the pink molecules on the surface of my blood are not referred to as antigens as they are not foreign, but the green molecules on the surface of group B blood are referred to as antigens as they are foreign?


texts: What is the mechanism responsible for long-lasting detectable antibody titers?

texts:
As I understand, when naive B cell encounters antigen matching its receptors and is activated by a T helper cell, it can either differentiate into 4 plasma cells, produce a lot of antibodies and commit apoptosis, or into 2 memory cells waiting to be activated the next time they encounter the antigen.
On the other hand, IgG can be detected for a long time after infection.  As antibodies decay, there must be long-term production of IgGs to keep their level constant.  What is the mechanism behind that if there is no following infections?


texts:
I found this bug (actually he found me) while walking through some bushes in the city (Iași, Romania).
It is a small bug, a quarter of a fingernail, white and a fluff tail. He lays a white fluff on bushes (that is how I meet him, I brushed the bush and got the white fluff on me, when I wanted to clean it off I saw 2 moving on my shirt) and it seems they stay around it. I also found it near the plants, on a stone pavement, but I presume he got lost.


texts: Do cells store information other than permanent (chromosome) information

texts:
The brain stores information in neurons (i.e. neural networks), and cells store information in DNA. But with DNA, this is permanent information. There is a lot of potential temporary information in the cell as well. The brain deals with temporary information in the short term memory, maybe there is something parallel in the cell. Wondering if there is any temporary or localized information cells store related to their processes such as for gene expression or their interaction with the external environment.

Maybe this looks like they have a small recombinant DNA strand that is used for creating some temporary proteins or such things to temporarily store information. Wondering if anything like this exists in cells and/or is studied.


texts:
We buy some run of the mill big-box store cat food. Over the last several weeks, I've observed a blue jay landing on the cat food dish, taking a piece or two, and flying off with it. I assumed it was eating it then, and this morning I just saw it actually eat a piece.

Why would a blue jay eat cat food?

Edit:

I just looked at the ingredient list and apparently corn is the first ingredient. But there's also "poultry by-product" and a variety of other "meats." Would the jay just smell a lot of corn or something?


texts:
So I'm reading about how mutations in DNA can be caused by oxidative damage. An example of a product of oxidative damage is given: 8-oxo-7-hydrodeoxyguanosine

My textbook says that this product frequently mispairs with A, resulting in a high level of G-->T transversions.

What I'm not understanding is why it's a G-->T transversion. If the 8-oxo-G is pairing with A, resulting an an A-G pair, isn't this a T-->G transversion? Or does the order not matter?


texts:
I found that some books include cytokinesis within mitosis, but some other books I have referred to include only the dividing of the nucleus as mitosis and do not include cytokinesis.

Can anyone help me out? Please include a source in your answer.


texts:
This is a picture I took of my mystery weed out by Pittman wash in Henderson NV earlier this year. From my experience this last year, I assume that the plant turns red later in the year and loses the bottom leaves. The plant typically seems to grow no more than half a foot tall but can grow a couple feet wide at or near the top.
Edit: I wasn't able to get a background but here are more pictures


texts: Using distilled water on sterile swab for collecting microbes on solid surfaces

texts: I was wondering if it is acceptable to use distilled water on a sterile swab for the collection of microbes on a solid surface. - in this case, Salmonella and Shigella.


texts: How can paleontologists identify morphologically different fossils as members of the same species?

texts:
I recently saw a documentary about Tyrannosaurus rex, which detailed the growth stages of the dinosaur. Apparently, it underwent a huge growth spurt at around 14 years of age, growing into the massive predator so well known in the popular imagination. From what else I've read, this much seems uncontroversial.

However, it made another claim which is that pre-teen Tyrannosaurs had a radically different morphology from adults. The skull was smaller, the legs much longer and the two-fingered forearms far larger in proportion to the rest of the body.

Given that there is some limited evidence for the animal living and hunting in social groups, the program speculated animals of different ages may have filled different hunting roles. The faster, more agile teens driving prey toward the massive, slower adults which then tackled the actual killing. Lions in Africa hunt in packs in this way, but whether Tyrannosaurs did remains speculative.

Anyway, on seeing the body plan of the young Tyrannosaur, I immediately wondered at how any palaeontologist could identify it as the same species as the adult. And lo, the documentary went on to say that, for some years, it was presumed to be a different species.

So the question is: given the radically different body shapes of these two forms and the limited evidence one can glean from the fossil record, how were scientists able to conclusively identify that young and adult tyrannosaurs were, in fact, members of the same species?


texts: Is fructose really a poison like alcohol?

texts:
I came across this video claiming that fructose is like a poison with detailed explanation on how it is metabolized. With a search on internet I found an article which challenges the claim and sounds convincing. In the article I also learned that the original claim was made by Dr. Robert Lustig.

Dr Lustig is a scientist and the article is not a peer reviewed scientific article. I am not an expert in the field and I am not sure which side is right.

Could you tell me which side is right?


texts: I'm looking for some book suggestions on oncology, preferably I want them to be fairly recent. I am not worried if they are fairly technical, as long as they have good accurate content and layout.


texts: What is a detailed chemical explanation for describing how an enzyme may lower the activation energy of a reaction?

texts: If you can provide some sound reasoning that touches on tertiary structures of proteins and does not use a lot of advanced chemistry jargon that might be really helpful, especially for an intro biology student.  I think my problem is that activation energy is lowered by an enzyme and I know how its like on the Gibbs Free Energy diagrams.  However I think I've been taking this as an axiom and I'm not really sure why.


texts: How are fluorochromes conjugated to proteins such as antibody?

texts: How are fluorochromes like FITC conjugated to antibodies? Are they covalently bonded? If they are covalently bonded, will low temperature (-20 Celsius or lower) break the covalent bonds and detach the fluorochrome label from the protein?


texts:
I am currently studying biology and would like to know why enzymes work best in a particular narrow range of pH (the so-called pH optimum).

Unlike temperature change, I do not think this has much to do with energy. Do pH-related changes in enzymatic activity have anything to do with the active site?


texts: Have novel interactions or pathways been predicted by GRN or PPI data and later confirmed by experiment?

texts:
I've been learning about the gene regulatory network (GRN) and protein-protein interaction network (PPI) recently.
I've found a huge amount of extremely interesting papers about how biological network data is accumulated and how it can be studied.

However, what I haven't found is any examples where the network data was used to make a novel prediction which was later experimentally shown to actually exist.  What are some of the cases where this has happened?


texts: Do all body organs grow in proportion during the period of physical development?

texts:
It is obvious that during childhood and puberty, the human body grows uniformly or proportionally so that a child's arm length, for example, is shorter than an adult's arm length but is proportional to a child's leg length.

What I'd like to know is whether the same is true for internal organs, or are there any organs (even external but perhaps less obvious) that do not grow in dimensions when the rest of the body grows and develops (I am talking about physical growth).


texts: Does embryonic development mimic (partly at least) the evolution of organisms on earth?

texts: What do we know about the forces/mechanisms which lead to this seemingly "fast forward" evolution stages of the embryo? What are the theories dealing with this idea?


texts: What is the difference between gene and CDS annotations?

texts:
I have a bunch of sequence files fetched from the EBI ENA and I'm trying to find the end of the 5' UTR for specific genes.

The UTR itself doesn't seem to be annotated in most sequence files I have. My original idea was to simply use the CDS annotations, as the start of those should clearly identify the end of the 5' UTR. But I also noticed gene annotations in many of the sequences, most of them starting and ending at exactly the same locations as the corresponding CDS annotation. But there are also cases where there are small differences between the gene and the CDS annotation.

So I'm wondering how exactly the gene annotation is defined (if there is actually an agreed definition) and how the gene and CDS annotations are used in practice.

Which annotation would be the most reliable to identify the end of the 5' UTR?


texts: Is it dangerous to eat a mutated eggplant descended from a radioactive ancestor?

texts:
What is the risk, if any, associated with eating a 100th-generation mutated eggplant derived from a radioactive ancestor?

In another word, is that possible that organic toxin will be produced by the mutated plant and is it a good idea to plant it in America? These plant seems very beautiful to me! Ha Ha

Note: The descendant eggplant is not radioactive.

Motivation: There are many mutated eggplants around Japanese power plants.


texts: Examples of animals with different number of chromosomes that can interbreed?

texts:
When I was first started to write this question, I wanted to know how species evolve to have a different chromosomal arrangement, such as having two pairs of chromosomes instead of one? However, I think I have resolved my misunderstanding by reading:
http://scienceblogs.com/pharyngula/2008/04/21/basics-how-can-chromosome-numb/

My basic misunderstanding was that I thought animals with a different number of chromosomes couldn't reproduce, which appears to be wrong. My question is now, are there examples of animals that can interbreed that have a different number of chromosomes (particularly offspring that are not sterile)? Is there a species that is known to have a variation in the number of chromosomes (yet, somehow, hasn't yet resulted in complete speciation); or are there two species that can be interbred and result in fertile offspring?


texts: Role of ATP and AMP in functioning of Phosphofructokinase

texts:
I know that when ATP is more then it inhibits PFK and hence regulate the number of ATP. But how does PFK reactivates itself? Is it due to removal of ATP from allosteric site that just reconfigures the enzyme back to normal functional state, or does binding of AMP (after ATP removal) does that?

To clear the meaning,

PFK+ATP= (inactive PFK+ATP)

So is it (1) or (2)?

(1) (inactive PFK+ATP) => (Active PFK)+ATP

(2) (inactive PFK+ATP) => (Inactive PFK)+ATP removed => (Inactive PFK)+ attached AMP => (Active PFK) + removed AMP


texts:
How can I improve my Gel Extraction yields. We use the standard protocol from Qiagen, gel extraction, dissolve in QG buffer at 42C and purify via anion exchange columns. However, with 500 ng we ultimately get 100 ng for a 20% yield. I was curious what else has been tried for gel extraction.

We also add IPA and NaOAc to the dissolved mixture prior to the column purification.


texts:
Archaeologists and historians strongly claim human beings originated from the African continent, where the default color is black for humans.
Why are all human beings not black in color?


texts: Why is there extreme itching when we touch a hairy caterpillar? What are ways to stop itching?

texts: I mean there are lot of caterpillars or hairy caterpillars to be more precise when we touch those hairs we get extreme itching on that area i want to know why we got that itching? Ok i know that it must be some chemicals but which? And if one has got itching how to remove it?


texts: What is solid-phase bridge amplification?

texts: During Illumina sequencing there is a step called bridge amplification by which DNA is amplified by isothermal enzymes. What is this stage, and how does it work?


texts: When subtracting background from a Western blot image, does the method of subtracting background signal have to be the same for all blots analysed?

texts:
I am analysing some Western blot images and I want to subtract the background signal for my protein bands of interest. Previously, the way that I subtracted background was to draw a rectangle (that was the same area as the rectangle outlining my protein band of interest) at the top of each lane, and subtract the integrated density of this background rectangle from the integrated density of my protein band.
However, I have read a paper about different methods of subtracting background from a western blot image. In the paper it states: "The area (usually a rectangle) that is used for background subtraction is usually placed above or below or is an average of the intensity of the area above or below the band of interest".
However, for one blot I have, the background in the area below my target protein bands is much higher compared to the background in the area above the bands.
For this blot, I am considering drawing 2 background rectangles, one above and below the protein bands, and taking the average of their integrated density.
I think this method would give me a more accurate measure of the background compared to drawing a single rectangle at the top of the lane.
Since I only have this uneven background problem (where the background is a lot higher in the bottom half of the blot vs the top) for one blot image, I don't think it would be necessary to use two background rectangles for the other blots.
I am analysing pictures of many blots, where I have labelled for a variety of proteins. I am wondering if the way I subtract background from each blot image has to be the same? Or is it ok to use different methods of background subtraction depending on the unique background situation for each blot?
Any insights are appreciated.


texts: Why does K+ have more concentration inside of the cell compared to outside of the cell? Why is Na+ and Cl- the opposite?

texts: Can someone tell me the fundamental reason why K+ has low concentration outside of the cell and more inside of the cell?


texts: Can a person really die quickly from biting their tongue?

texts:
A common trope in certain circles (like Eastern martial fiction), is someone committing quick suicide by biting his or her tongue.  But is this really possible?

The internet turns up millions of pages of speculation, but no Straight Dope.  People have been removing the tongues from mammals, and each other, throughout human history.  There has to be some scientific data on this somewhere.

Will an untreated, severe, lingual laceration, really result in bleed-out of an otherwise healthy human?

Or will lingual trauma facilitate swallowing the tongue sufficiently to cause asphyxiation?

What does the science say?
Thanks!


texts: Are the cells (structures) of deep sea fish different? And can they survive in shallow water?

texts:
In the deep oceans the pressure is enormous. But still there are fish living. But are the cells of them different from fish who just live at the surface of waters?

For example, are the cells smaller because of the pressure? And if so, does that influence the inner metabolism? If not, how do they succeed in maintaining their size?


texts:
We know that mycorrhizal association helps the plant to absorb nutrients.
Why can't this association be exploited in agriculture ?

Can't we add spores of the specific fungi to specific plant and enjoy the benefit of this association as we would not have to add many fertilizers ?( We could add organic manure whose main drawback is the time it takes to release nutrients. The fungi could probably solve the problem.)


texts: Dynamic of the number of cells over time as the embryo grows

texts:
I would like to investigate the dynamic of the number of cells over time as the embryo grows. I am interested in any multicellular animal species for which we can have some data. How does the number of cells change over time in an embryo?

I welcome any graphs, empirical data and/or mathematical expression for this dynamics.


texts: Is the number of protons in the mitochondrion sufficient for ATP synthesis?

texts:
If the proton concentration in the mitochondrial matrix (based on its pH) is multiplied by its volume, the total number of protons in somewhere in between 2 and 8.

  My question is whether this is sufficient for ATP synthesis, if 2–3
  hydrogen ions are required for each molecule of ATP synthesized.

My calculation is as follows:

pH = –log[H+]

The pH of the mitochondrial matrix is ca. 8. Thus, [H+] = 10-8 M (moles per litre).

If the mitochondrial volume is 0.2 μm3 this is equivalent to 2x10-10 μl = 2x10-16 litre

Using Avagadro’s number as 6x1023 it follows that:

Total number of protons in the matrix of a mitochondrion = 10-8 x 2x10-16 x 6x1023

= 1.2 (although other figures may give a value as high as 8).

If a pH of 6.8 is considered for the inter-membrane space along with a 0.1 fl volume, the number is 6.7 protons.

I found a paper where the question is adressed. First, the definition of pH at very low volumes is challenged, along with its measuring techniques. Second, it proposes novel mechanisms for proton availability in such situations.
(http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0045832)


texts: Availability of a database containing the proteins of Vibrio cholerae and their corresponding gene sequences

texts: I wanted a list of all the proteins (amino acid sequences) and their corresponding gene sequences of Vibrio cholerae. I tried to search in patric, but the number of amino acid sequences and gene sequences do not match, as they have provided the whole genome. I need to know if there is a database where all the proteins of Vibrio cholerae and their corresponding gene sequences can be obtained in a single file or in a couple of files. Copy pasting 4000-5000 genome and protein sequences individually from the internet seems cumbersome to me.


texts: Why do body parts sometimes get a itching and tingling feeling when falling asleep?

texts:
Just before I fall asleep I sometimes experience an itchy and stinging feeling in my body parts. It can be that the nose or neck suddenly start to itch or a tingling stinging feeling in the legs. Sometimes my fingers also start to do small uncontrolled movements.

What is this about?


texts: The Cambrian explosion was 540 mya. Laurasia and Gondwana didnt collide until 330 mya. So for 210 million years the land was divided into two large continents. Plants and insects had already colonized the land long before Pangaea formed. It should therefore be possible to divide land plants and insects into two broad groups. One group that inhabited Laurasia and one group that inhabited Gondwana. I have googled around but I cant find any good info on this.


texts: What is the core mechanism behind neuroplasticity?

texts:
Specifically I am looking at reopening of the critical period of plasticity.

Modern neuroscience has started to unlock the secret of neuroplasticity.

A common experimental setup is with mice. They have a critical period between days 20 and 32 when they learn binocular vision. And if you cover one eye during this period, they never learn to use it properly. Covering the eye even for extended periods outside of this window has no long term effect.

Scientists can then test out various plasticity hypotheses. And they had indeed found several mechanisms that can restore binocular vision to adult mice.

You can find a list towards the bottom of this paper: Autism -- A 'Critical Period' disorder?

enzymatic degradation of PNNs
SSRI
HDAC inhibitors (which are suggested to knock out Nogo-66 receptor)
AcetylCholineSterase inhibitors

It is suggested that there is an underlying pattern of excitation/inhibition (E/I) balance that all of these 4 techniques perturb.

Where can I read about this E/I balance in detail? The Wikipedia page on NeuroPlasticity (here) appears to be a dead-end.

I am looking for an overview, rather than technical scientific papers that explore a particular aspect, already assuming familiarity with the big picture.

How to get the big picture?

EDIT: T K Hensch seems to be a world leader in this research, and his papers answering my questions, for example http://www.ncbi.nlm.nih.gov/pubmed/24439367


texts: What is the function of oxyphilic cells in the parathyroid?

texts:
Apart from the chief cells, which produce and secrete parathyroid hormone (PTH), the parathyroid gland has another type of cells, which are large and fewer in number, have small, dark nuclei and an acidophilic cytoplasm with many mitochondria. These cells increase in number with aging. As far as I know, we still have no knowledge of what role they perform, or why they increase with age.

Is this true, or are there already some concrete ideas about this?


texts: What factors affect the rate of transpiration in plant leaves?

texts:
I'm trying to get my head around factors which affect transpiration in leaves.

For example, how would applying petroleum jelly to the surface of plant leaves affect their rate of transpiration?

I get that it's basically going to decrease the trasnpiration rate because the stomata will be covered, but I'm not sure about these parts:

How would it affect the rate of transpiration if only the top surface was covered?
How would it affect the rate of transpiration if only the bottom surface was covered?

Also, I think I'm right in saying that increasing wind / applying a fan to plant leaves will increase the transpiration rate, but why?


texts: What physics knowledge can be applied to biology of organisms and ecosystems?

texts:
In the wiki page of Biophysics:

  Biophysics spans all scales of biological organization, from the molecular scale to whole organisms and ecosystems.

But after searching on the internet; the dominant application of physics in biology that I see is at the molecular scale. In the wiki page Mathematical biophysics, there is a lot of interesting information, but it is only about mathematical knowledge applied to biophysics, not physics itself.

What, if any, physics knowledge (based on principles and laws of physics) can be applied to biology in the sense of organisms and ecosystems?


texts: Found this spider in my bed last night.. can someone help ID?

texts:
As I was going to bed last night, this little guy greeted me when turning the covers. Can someone help ID this for me? I'm located in Kentucky, USA.

Demonstrating size, compared to a bottle cap:


texts:
This species of bird was spotted in Kakadu National Park, NT, Australia. It looks a bit like a lemon-bellied fly catcher, but I think my bird here is a tad bigger than the fly catcher, but I am unsure.

I was hoping one of the more ecologically proficient people here could help me out.

Note: This is the 3rd related question on this topic, so feel free to close-vote-for-whatever-reason, but I am generating a photo album with all the birds I have spotted there (heaps!), and a few of them I can't identify with the limited resources I have.


texts: Is there any reason for the variation in mitochondrial DNA size?

texts:
As my textbook An Introduction to Genetic Analysis points out, yeast mitochondrial DNA has approximately 78 kb of genetic data, while the human mitochondrial DNA contains 17 kb. Is there any evolution reason for this drastic change in size? Also, are there any particularities about mitochondrial function that have been compromised with this reduction in size?

References

Griffiths, Anthony J. F. An Introduction to Genetic Analysis. New York: W.H. Freeman, 2000.


texts: Do artificial light sources cause enough fatalities in light-attracted insect species to cause eventual extinction?

texts:
There are various theories about how insects are drawn to light bulbs because of navigation mechanisms based on the sun and moon's position in the sky. It makes sense for that to work when the only major light source on Earth was high in the sky at a very slowly changing angle, but now that we have artificial lights it seems like that would severely interfere with the regular life cycle of insects. Being stuck buzzing around a light bulb for almost half of every day seems like it could be damaging to the life expectancy of each bug, and therefore damaging to the species as a whole.

But the reality is, most of the "livable" surface on Earth is not covered in cities, so most of the bugs aren't affected by these artificial lights.

So that leaves me wondering, if we expanded our cities to cover most of the earth livable surface, would we potentially kill off a large portion of the bugs on earth that are drawn to light or rely on bugs drawn to light as a food source?

That's sort of a hard question to answer though, because of so many factors, however I think the root of the question is a simpler one:

Do artificial light sources cause enough fatalities in light-attracted species to prevent them from successfully reproducing at the necessary rate for survival? (assuming the whole species were subjected to such light sources)


texts: What is the physiological mechanism for getting unconscious after a punch to the head?

texts:
It is the everyday life in boxing: One boxer gets a smack in the head, cannot do anything for many seconds and then: Victory of his opponent due to a Knockout!

What is the reason for losing consciousness for a short time by e.g. a strong smack in the head?

Are there any neuronal reactions that cause this?


texts: How to interpret Percent identity matrix created by Clustal Omega?

texts:
I did a multiple sequence alignment using Clustal omega. checked similarity for 3 protein sequences : aspartyl aminopeptidase [Homo sapiens], aminopeptidase P (APP) [Plasmodium falciparum 3D7], yeast aminopeptidase (S000001586)APE1. I got Percent identity matrix as

Percent Identity  Matrix - created by Clustal2.1

 1: PF3D7_1454400              100.00   16.18   20.35
 2: gi|5902181|gb|AAD01211.2|   16.18  100.00   29.66
 3: S000001586                  20.35   29.66  100.00

My doubts:

I would like to know how to interpret this matrix result
Coming back to sequence alignments results, when I click on 'Show colors', the alignment summary is colored in 4 colors - red, green, blue and pink. Can anyone help me in decoding the color reference of alignment summary?

Thanks


texts: Would it be possible to force the pineal gland to release dimethyltryptamine on command?

texts: To my knowledge, the pineal gland is responsible for the release of dimethyltryptamine (DMT) upon death.  Would it be possible to force the pineal gland to release this DMT while still living?


texts: Enzyme Inhibition in relation to Aspirin

texts:
I see that aspirin (in part) works by inhibiting cycloxygenase isoenzymes and that this inhibiting is irreversible. I've had a few classes mentioning this topic in passing, but never with depth.

I guess my question regards the permanence of the word "irreversible." I assume enzymes have a life span, so to speak, and that the same isoenzymes both die and are being replenished at some given rate.

Am I correct in thinking that the cycloxygenase enzyme is permanently inhibited until its death (catabolism)?


texts: How much influence does toxoplasmosis have on personality and intelligence?

texts:
Latent toxoplasmosis affects up to 1/3 of the human population and up to 40% of the population in Australia.  I have heard that latent toxoplasmosis has many significant undesirable effects on personality, such as decreased novelty-seeking behaviour, and decreased intelligence quotient.

While these changes are statistically significant, I'm wondering if anyone knows the magnitude of these personality and cognitive changes, since a statistically significant result doesn't necessarily imply that there is a large difference in personality between those who are infected and those who aren't infected.  Also, can one succeed in an academic career path if one becomes infected with toxoplasmosis?


texts: Why does scraped knee hurt more in hot water than cold water.

texts: I was asked this question by my 5year old son. I do not know how to explain to him .


texts: Why is untreated trypanosomiasis invariably fatal in humans?

texts:
If left untreated, African trypanosomiasis will invariably kill the patient. The human immune system is unable to clear the infection.

I am aware of a few other infectious diseases with this property and I have a rudimentary understanding of the reason why. For example, I'm told that rabies has evolved to be uniquely good at attacking the brain because that's the only way it can spread to other hosts, and the neuroimmune system, being quite different from the peripheral immune system, is not capable of dealing with a virus that has this property.

I do not understand why the human immune system is ineffective against trypanosomiasis. One explanation I was offered is that the human immune system is just not very good at fighting parasitic infections (compared to viral and bacterial infections). However, this can't be the full answer, because there are other parasitic infections that may go away on their own without treatment.


texts: Is plastic just as good for you as corn?

texts:
To specify, I mean plain corn-on-the-cob, not anything processed like corn flakes.

Since one of the main important functions of corn is that it's not digestible, and therefore helps with digestion by loosening feces, would that make it just as beneficial as chopping up and eating a plastic bag?


texts: What bird is this seen trekking in Nepal during descent on Manaslu circuit?


texts: Is the book "Bioinformatics for Geneticists" outdated?

texts: I am going to be working with genetics data in my organization's data warehouse next year and helping our biotechnology department.  I work in academic research, but I have very little genomics background.  I was able to find the book called "Bioinformatics for Geneticists" (Edited by Michael R. Barnes & Ian C. Gray) at a used book store for a couple dollars.  It looks like it was published in 2003.  Do you think this book is too outdated, or would I still get a good introduction to the subject?  If you think it's too outdated, what book(s) do you recommend?


texts: In (human) zygote cell differentiation, do we know how the cells coordinating the process know their current position?

texts:
I've seen this question asked in a mature person -- e.g. lip cells will create more lip cells -- but how about in the developing zygote.   I've seen neighboring cells help determine the type of the new cell. Do we know how they know where they are located, and how many cells of a certain type have already been made, making "lips" complete, or teeth, etc.  So in summary:

1) how do the cells in the growing zygote know "where they are", assuming they need to, to determine what cells to build where for the body?

2) how do the cells know, when the cells of that type building a bone or lips or teeth, etc, are done, since obviously many participate in the process. ?


texts: Because we don't live as closely to livestock, are we at a greater or lesser risk of plagues?

texts:
Give recent events, some people have called for the 'wet markets' in China to be shut down, (for many reasons) but largely because it is likely the source of the recent plague outbreak, due to the close human-animal contact there.

(I am not here to debate if the markets should or should not be closed down. That is something for another question.)

However looking at the (very short and incomplete) history of the smallpox vaccine: Someone noticed that milk maids didn't have the ugly smallpox scars those who had survived a smallpox infection had. They conjectured the maids had caught the mild cow pox off their cows, and had gained an immunity to smallpox as a bonus. Cowpox was then developed in to a vaccine, fast-forward a few years and now smallpox has been eradicated. The 'natural' cow pox was basically an attenuated live vaccine for smallpox.

Now today we have supermarkets and mechanized agriculture and so have far less contact with animals (e.g. back in the day many households would have their own cow and chickens, we rode horses for transport, etc.) Therefore we have less of a chance to develop immunity to 'naturally attenuated' diseases, which they can immediately fend off if the disease does mutate/break the species barrier into a plague worthy foe.

I am not suggesting we should go back to milking our own cow before breakfast, however:

Does our lack of contact with domesticated animals mean we have less 'naturally attenuated' disease exposure and therefore we are at a higher risk of plagues?


texts: How come the role of the Apis mellifera is determined by nutrition rather than chromosomes?

texts:
Prior to making my question I browsed on similiar question such as this one but it doesn't specifically addressed my doubt in the sense that it is related with a different species and on a concept not mentioned in that question. More specifically on whether does nutrition may influence genetics on the sex determination or not?.
My doubt arises as I'm learning about Partheneogenesis and genetic determination of the sex. Upon reading this entry in Wikipedia, it explains that a queen bee of the Apis mellifera is determined during the development of the larva. The article doesn't state anything about the chromosomes of the larva. It just states that the queen will develop into that by feeding it from royal jelly, from which I believe it has some sort of protein that may influence the development of such larva giving it their characteristics.
But this topic is letting me confused. Does this means that for example a male bee can become into the queen?.
This article explains that some insects produce haploid males from unfertilized eggs by I believe Partheneogenesis. But if the bee doesn't mate, how is the sex determined?. I believe that it will produce only females (as his genetic sex determining chromosome is ZW?) and as such will yield only females, but if the queen does successfuly mate with a male may produce males which in turn can also lay eggs (by Partheneogenesis) and those eggs will all be males?.
From this I'm getting the conclusion that it can occur that some individuals may be all females or all males?.
How come is it possible for an haploid organism get into full develpment isn't it necessary to be diploid?. Do they become into diploid at some moment?.
Can someone help me to clear out this doubt?. This topic has left me confused, so an answer which would help me the most is some sort of explanation on the concepts of partheneogenesis and sex determination in the bees.


texts: Genotypic distribution of a population with two characteristics and linkage

texts:
I am currently doing some research into distributions and probabilities with Mendellian genetics. I came across this problem that I cannot seem to wrap my head around.

Given that the population has two characteristics, they are color and texture. Supposed two dihybrids reproduce (AaBb x AaBb) and if the dominant form of the
color gene is contributed, then the dominant form of the texture gene is three
times as likely to be contributed as the recessive form. If the recessive color gene is contributed then the dominant and recessive genes for texture are equally likely.

From this the geneotypic distribution has to be calculated.

I know the solution is:

[9/64   6/64   1/64   3/16   1/4   1/16   1/16   2/16   1/16]

 AABB   AABb   AAbb   AaBB   AaBb  Aabb   aaBB   aaBb   aabb

When I performed the punnett square I got the distribution of:

 [1/16   2/16   1/16   2/16   4/16   2/16   1/16   2/16   1/16]

 AABB   AABb   AAbb   AaBB   AaBb  Aabb   aaBB   aaBb   aabb

and did not know where to go from there.

My question is how did they incorporate the "times as likely" condition into the solution.


texts: Cellular Respiration/Fermentation Problem Leading to Lack of Energy

texts:
A young animal has never had much energy. He is brought to a veterinarian for help and is sent to the animal hospital for some tests. There they discover his mitochondria can use only fatty acids and amino acids for respiration, and his cells produce more lactate than normal. Of the following, which is the best explanation of his condition?

A) His mitochondria lack the transport protein that moves pyruvate across the outer mitochondrial membrane.

B) His cells cannot move NADH from glycolysis into the mitochondria.

C) His cells contain something that inhibits oxygen use in his mitochondria.

D) His cells lack the enzyme in glycolysis that forms pyruvate.

E) His cells have a defective electron transport chain, so glucose goes to lactate instead of to acetyl CoA.

Answer:  A

A) So, from this assumption, pyruvate would build up in the cytosol of cell. However, I do not see why lactate would be formed. Lactate forms when there is a lack of NAD+. In this case, there is no problem with NAD+. All NADH will be recycled into NAD+ by the Electron Transport Chain in the mitochondria.

B) I do not know what will happen in this case. Too many contradicting factors. Can anyone explain?

C) This is clearly not correct. If there were no O2,then there would only be lactic acid fermentation; the protein and fatty acids would not be used.

D) If lactate is formed, pyruvate must have been formed.

E) The electron transport chain needs to work. See C). Same explanation.

So, I am debating between A and B. Can anyone explain why the textbook says A?

EDIT :
If anyone could give me a step-by-step approach to solving this problem, I would really appreciate it. This is supposed to be a challenge problem not representative of test questions, but I still want to fully get it.


texts: Why does decomposing matter emit a bad smell?

texts: Often, when matter decomposes (such as a rotting carcass), a nasty smell is emitted.  After speaking to my teacher, it was likely due to the nitrogen compounds that leads to the bad smell.  Is this so?  Why then, do nitrogen compounds smell bad to us humans?


texts: What resolution and or DPI would a TV or VR headset need to be to equal 20/20 vision? and 20/10? With even the 4K TV it does not seem as sharp as my own vision.


texts: Why is this the equation for the fitness of cooperators?

texts:
This paper gives the equations as:

The fitness of cooperators and defectors is respectively given by fC = b(i − 1)/(N − 1) − c and fD = bi/(N − 1).

c - cost
b - benefit
i - number of cooperators
N - population size
For the equation fC, does this mean
(b(i − 1)/(N − 1)) − c, i.e.:
$$
\frac{b (i-1)}{N-1}-c
$$
or b(i − 1)/((N − 1) − c), i.e.:
$$
\frac{b (i-1)}{{N-1}-c}
$$
Guessing the former but I just want to check.
While we're at it, could someone explain why this is how fitness is modeled?


texts: Can you help with insect identification? (Outback Australia)

texts:
This was in my child's shoe that was left outside. They got it out of the shoe and it went on the wall where they measured it. The body is approx 3 cm and from head to tail it's 6 cm. Any help would be greatly appreciated!

We are in central Australia in the Outback.


texts: conversion of distance matrices to pdb/coordinates

texts:
I am currently facing two transformational issues. Suppose I am given a protein's residue sequence and calpha distance matrix; is there a way to generate the 3d coordinates of the protein's residues from this information(I think there theoretically should be since it is a bijection up to rotation/translation).
The second issue I am faced with is generating pdb files. How does one make a pdb file given the coordinates of the protein's residues along with the sequence? Is this enough information?


texts: How do viruses provide selective advantage

texts:
I've heard in many talks as a passing, well-known fact that viruses(e.g. pathogenic HPV strains) offer selective advantage for the infected cell to multiply. But I'm not able to quite wrap my head around this.
I assume this has something do with episomal qualities of viruses, but how exactly does that does translate to selective advantage.
My intuition says that if there is an uneven segregation of the viral genomes to the daughter cells, than that heterogeneity can cause give selective advantage. But given no preface of the heterogeneity of a virus during cell division, how is one able to claim that viruses offer selective advantage?
Background: I am not a biology person, but rather computational scientist who works with biologists.
one example source


texts: How much of my ancestry will match with my brother?

texts:
Recently, my brother (full sibling) got his ancestry checked from MyHeritageDNA. They have a similar service like 23 and me and I've found out that both companies are offering the basic service almost the same, with some add-ons which are different.

My question is that if I (I'm a male) send my DNA sample to either organization, how different should I expect the results to be?


texts: Which is the best way to fix and preserve comet assay slides before staining with Ethidium Bromide?

texts: I want to use the method of Single Cell Gel Electrophoresis (comet assay). I have many samples, but I don't have the appropriate microscope. So I have to preserve my slides until the time comes for staining and microscopic analysis. I've read many different protocols, and I can't decide which is the best. Also, after the staining and the analysis, I might need to reuse the same slide. Is that possible? and if yes, what should I do?


texts: Can 12 mitotic divisions produce 6000 nuclei?

texts:
The following quote is from "Principles of Development" by Tickle & Wolpert:

  "After fertilization and fusion of the sperm and egg nuclei, the zygote nucleus undergoes a series of rapid mitotic divisions [...] The result after 12 nuclear divisions is a syncytium in which around 6000 nuclei are present in a common cytoplasm"

12 divisions (starting from 1 zygote nucleus) should produce no more than 212=4096 nuclei, not 6000. Is this just a simple error in the textbook? Alternatively, is there a biological explanation that makes the 212 estimation invalid?


texts: Can this theory on the evolution of human appearance be flawed?

texts:
This is what a friend of mine said:

  When there's human offspring, it will look a rough 'medium' between
  the two parents, with it sharing features from the two. well if the
  offspring of one set of parents has sex with the offspring of another
  set, the outcome becomes a 'medium' of those two. So the range from
  what we shall call 'completely average looks' (a hypothetical state of
  the average of everyone in the world, which is acceptable as we're
  looking at a process of millions of years) becomes less and less the
  further into the future we go. Eventually, there is almost no range
  between people and 'completely average looks'.

In summary: take the hypothetical average of everyone in the world, and because the offspring of two people is a slight mixture of those two people, they are a tiny bit closer to the hypothetical average of everyone in the world, which means that eventually people will be getting closer and closer to this average, so will one day look the same.
So he's suggesting that slowly people will become more and more similar.

My argument is that, although this baby may be that tiny bit closer to the overall average, they're new look has effectively altered the average, meaning that they aren't actually getting closer to the average.

I'd like an opinion and flaw from some experts, such as yourselves, so please...


texts: Elastic arteries and muscular arteries supplying to upper body

texts: What are the elastic arteries and muscular arteries supplying blood to upper body (above heart) in humans?


texts:
Currently I'm reading She Has Her Mother's Laugh: The Powers, Perversions, and Potential of Heredity, a fascinating book about heredity by the popular science author Carl Zimmer.
While reading this I came across this following passage, which bothers me.

It also meant that the inheritance of acquired traits - taken as a fact by Hippocrates, Lamarck, and Darwin alike - was impossible.
~ Chapter 2: Traveling Across the Face of Time

I've read Darwin's The Origin of Species, and a fair bit of other stuff on Evolutionary Biology, and as far as I know Darwin clearly opposed the idea of Lamarckian heredity. Which is why I was quite surprised to see this, from Zimmer, who's a very highly reputed author. How can he make such an obvious mistake, or is there something more to it than I know? Did Darwin ever agree with some form of Lamarckian heredity?
EDIT
Here's the passage of the book where it appears, for context.


texts: At what substrate concentration will an enzyme work at 40% of its maximum rate if its Km = 0.095M?

texts:
The question involves the Michaelis-Menten kinetics equation.

Here is what I did: I took the Michaelis-Menten equation, replaced v with 0.4Vmax, canceled the Vmaxes (one on each side), and solved for [S].

I got -0.056 which is obviously wrong, because [S] cannot be negative.


texts: Is there difference in stomatal density in young and mature leaf?

texts: If stomatal density varies in young and mature leaves then what may be the reason for this.which surface of the leaf has more stomata?how to distinguish abaxial and adaxial surface in monocot.


texts: does order of genes in a chromosome matter?

texts:
does the order of genes within a chromosome matter? or is the main thing that the genes are there.

so for example, our DNA is very similar to that of apes not only by the genes themselves but also by the arrangement of those genes in the chromosomes.

is the order of this arrangement significant? Or if it were shuffled around, then the functional impact would be more or less the same?

Another example, an international study in the mouse genome has revealed that virtually all mouse genes have direct counterparts in humans, i.e. humans and mice contain virtually the same set of genes. is the difference between humans and mice due primarily to the different order of the genes or to the slight differences in the genes themselves?

This question was raised from a claim here which seems to imply it does not matter.

  The chances are infinitesimal that human chr 2 were to resemble those
  of other primates at random. This is what you say in science when you
  mean 'impossible'. One simply doesn't see a segment of DNA the size of
  Chr 2A and 2B being so similar for such a length when we look at rats,
  dogs, worms or any more distantly related living thing.


texts: Can one see flickering of a light bulb at 50 Hz?

texts:
Yesterday I had a BBQ with some friends. The sun had already set and the only light source left (besides some ambient light from the world around) was a low energy light bulb.

After a while I started to see lighting changes in the faces of my friends and the number plates of their cars. It felt like someone toggled the light very fast. When looking at the wall or the light directly I didn't notice any flickering.

In my country the power grid is running at 50 Hz. Is it possible that I actually saw the flickering caused by the alterations in the power grid or am I just going insane?


texts: How dirty are bugs? And is it okay if they touch food?

texts: Sometimes I see people throw out an entire drink or bowl of food because a small bug was in it. Are they justified in doing this? Is there enough bacteria on common species of bugs (like ants, flies, beetles, dragonflies, caterpillars, moths, etc) to warrant any kind of health concern for a larger amount of food than what the bug was in contact with, or at all?


texts:
I'm reading  Williams' Adaptation and Natural Selection:
A Critique of Some Current Evolutionary Thought.

In this book the author talks about selection coefficients which, if I understand it correctly, can be calculated as finiteness arithmetic means (for each allele).

My question is: should this calculation be made assuming a ceteris paribus condition?


texts: Anatomy of nervous system's sensory pathways

texts:
When I touch my hand on a hot stove, I feel pain. I'm interested in knowing all the main "endpoints" (components/parts of the body) that are involved in relaying this pain signal. As I understand it so far, they are:

Nerve (thermoreceptor)
Fibers
Spinal cord
Brain stem (medula => pons => midbrain)
???
Somatosensory Cortex

A special sensory nerve in my hand, called a thermoreceptor, receives a thermal input (the hot stove) and fires a pain signal to my spinal cord.

My spinal cord then sends the signal up into the brain stem, where the signal travels through the medula, the pons and the midbrain.

At this point the signal is somehow wired to my somatosensory cortex; the part of the brain that ultimately processes the signal and interprets it as "pain".

Have I identified all the key players here? What connects the midbrain/brainstem to the somatosensory cortex?


texts: Does body absorb nutrients less efficiently if we ingest the same amount at the same time, opposed to spreading over a larger period?

texts:
I would like to understand if ingesting a certain amount of nutrients will result in different absorption from my body, depending on whether I ingest that amount spread over time or everything at once.

For example, considering all the food I eat in one day: does my body absorb the same amount of fat and protein if I eat that same amount of food all at once, compared with eating it spread by different meals?
Similarly, could it be possible that my body absorbs less fat if I eat 4 hamburgers at the same time, compared with eating them spread along the day?


texts: Do chilli peppers change in composition after they change color?

texts:
I grow some chilli peppers and was wondering when the time is right to harvest them. Of course gardening-focused sources say that they are ripe when they change color. This usually happens very quickly (1-2 days) after a long period when they remain green (1-2 months), which would suggest that the gardening advice might be right.

However, I would like to know the full story, so I tried to find some relevant research. Here's what I found so far (mostly paywalled, sadly, so I cannot read the details)

Development of pepper (Capsicum annuum) seed quality
Quite unrelated, but suggests that the end of the ripening process is not simply the end of it all

Variations in germination and longevity of pepper (Capsicum annuum L.) seeds harvested at different stages of maturation
Similar to the above, seeds still continue to change while the pepper changes color

Changes in Carotenoid Esterification during the Fruit Ripening of Capsicum annuum Cv. Bola
New carotenoids are produced during ripening

Formation and transformation of pigments during the fruit ripening of Capsicum annuum Cv. Bola and Agridulce
More information on the above

Carotenoid Biosynthesis Changes in Five Red Pepper (Capsicum annuum L.) Cultivars during Ripening. Cultivar Selection for Breeding
Carotenoid Composition in the Fruits of Capsicum annuum Cv. Szentesi Kosszarvú during Ripening
Researchers were apparently really interested in carotenoids in the 90s...

Variation in phenolic compounds, ascorbic acid and antioxidant activity of five coloured bell pepper (Capsicum annum) fruits at two different harvest times
This one suggests that there are still some changes happening after ripening: With advanced maturation, total antioxidant activity increased, however some antioxidant components such as ascorbic acid, total phenols decreased.

The influence of fruit ripening on the phytochemical content and biological activity of Capsicum chinense Jacq. cv Habanero
This one, while apparently full of interesting data, only deals with two stages of ripening(immature and mature).

Ripening of pepper (Capsicum annuum) fruit is characterized by an enhancement of protein tyrosine nitration
Very promising, but once again, research ends at the color change.

Evolution of total and individual capsaicinoids in peppers during ripening of the Cayenne pepper plant (Capsicum annuum L.)
The only article which actually deals with peppers which were left to ripen a bit more. Capsaicin content decreases as the pepper ripens, followed by an increase when it's over-ripe. Weird, but at least I was able to legally obtain this article. Unfortunately it deals with capsaicinoids only.

Is there more information about what happens to the chillies after they are ripe? I'm not really interested in heat, but rather in other chemicals which affect flavor and nutritional properties of chilli peppers.

Edit: Based on what I observe at home, the peppers do indeed seem to be changing for at least a week or so after the change in color. I left some red chillies on the tree and their color is now noticeably darker than those which have just ripened a few days ago.


texts: How many genes do we share with our mother?

texts:
Somewhere I have read we share more than 99% of our genes with every other other person and 98% of our genes with chimpanzees. What does this mean? Don't we share 50% of our genes with our mother and 50% with our father?

I've found an another article stating that.


texts:
Is there any relationship between the height of a tree and the number of branches emerging from the main stem?

I am particular interested in spruce or fir.


texts: Is it possible to stop more/extra fat from being stored in the body?

texts:
I don't mean simply by restricting eating or upping the activities, but a way to basically stop the body from adding more fat on itself down on the bio level. For example, I'm not too knowledgeable on this, but I believe fat is stored when the body can't make any extended use of extra energy put in to it.

Given such, could we simply direct the body to only use the energy needed and dispose of any "extra" while not storing it as fat/triglycerides? I know there are drugs that can speed up metabolism and etc., but this only heightens the body's ability to remove said fat -- not stop the process at which it is stored

This would be a great thing because then we could assure the body only uses the energy on what can be beneficial to us -- all the "rest" can be removed and not stored on us and being a con instead of a pro.

So in summary: Is there any feasible way this could be theoretically possible, given our biochemistry/physiology?


texts: Is protein intake required for the formation of new myosatellite cells?

texts: Hypertrophy of muscle fibers requires an adequate (significant, really) intake of protein, but what about just forming new myosatellite cells as a response to a stress applied to the muscle? Does that specific process require a comparable level of protein intake, or can satellite cells be generated with significantly less resources than what’s required to augment the muscle fibers themselves?


texts: Is there any reason an arbitrary DNA sequence such as 5'-ACACACACAC-3' would not exist in nature?

texts:
I am making a DNA model for my class, and I looked up some examples and they all have different sequences of bases. If I choose an arbitrary sequence like:

5'-ACACACACAC-3'
3'-TGTGTGTGTG-5'

or

5'-ATATATATAT-3'
3'-TATATATATA-5'

Is there any reason it would not exist in nature?


texts: I know that when RNA is transcribed from the original strand of DNA it contains introns and exons, and that the introns are spliced out of the strand to provide genetic diversity. However, what I don't understand is, how does whatever is doing this splicing know whether the section it is reading is an intron or an exon? Are there start and stop codes like there are for polypeptides, or is it determined by epigenetic factors like methyl markers? Or is it neither?


texts: Determining if a specific proline is cis or trans in the protein?

texts:
While peptide bonds usually adopt the trans conformation, peptide bonds to proline can exist in either cis or trans conformation. The isomerization between cis and trans is slow, and has been shown to be the rate-limiting step in folding of certain proteins.

What methods can be used to determine the conformation of a specific proline in a protein?


texts: we know when a human body cell infected by a virus , create interferon 1 to call other cells that surrounded it  , but red blood cells couldn't do this because they loose their nuclear and other organelles . I have a question about sperms , can sperms produce interferon 1 when they infected with viruses?


texts: Reference Request: Human visual system takes in $10^7$ bits/sec at the periphery and compresses it down to 50 bits/sec deep inside

texts:
In Sparse Components of Images and Optimal Atomic Decompositions by Donoho, 1998, the author claims that

  The human visual system is thought to do a tremendous job in achieving sparse representation of image data, taking $10^7$ bits/sec at the periphery of the visual pathway and winnowing it down to about 50 bits/sec deep inside.

Can somebody please point me to the source of that claim, as it is not mentioned in the paper, at least to my knowledge.


texts: Typical neuronal firing rates across the human cerebral cortex

texts:
I would like to find a scientific article (or articles), which would summarize typical neuronal firing rates in different parts of the human cerebral cortex.

Any good references on this?


texts: Origin of the double membrane of mitochondria and chloroplasts

texts:
Most websites and textbooks say that the double membrane of mitochondria and chloroplasts are a result of the endocytosis of ancient prokaryotes (the outer membrane is from the vesicle containing the prokaryote, the inner membrane is from the prokaryote itself).
However, some sources say that this is not the case. The precursor to the mitochondrion (alphaproteobacteria) was a gram-negative bacteria, which has a double membrane. This site says that the reasoning for the double membrane that is often taught is a lie, and that the mitochondrial precursor had a double membrane already to generate ATP through the ETC.

So, if this is the case, why do mitochondria now have two membranes, and not three (two from the prokaryote and one from the vesicle)?


texts: Correlation between muscle size and absolute strength

texts:
Is there a linear connection between muscle size and the power it can produce?
If not, why? And what is the true correlation if any, can it be described with an appropriate function? What other factors modify it? (Red/white fiber for instance?)


texts: Do biological phenomena follow Gaussian statistics?

texts:
I have recently entered the life sciences (from physics).  I am concerned about the use of p values in the life sciences literature.  For example, in this article, they test 9 - 12 rats in a control group and compare it to an experimental group.  They use p values to claim that their results are statistically significant.  This type of use of p values seems to be very common in the literature.

So here are my concerns :

Why is it so often assumed that biological measurements follow a normal distribution?  To my knowledge, this isn't known a priori.
From my physical intuition, it seems quite challenging to claim "statistically significance" when using such low sample sizes.


texts: Insect identification - Is this a bedbug?

texts: This bug was found on a couch in Cape Girardeau, Missouri. The couch, and the two beds in the room show no signs of other bugs. Is this a bed bug that I should worry about or something harmless? It was slightly larger than a common tick.


texts: Relative rates of migration of circular, linear and supercoiled DNA in agarous gel electrophoresis

texts:
I have read the supercoiled plasmid DNA migrates fastest when subjected to agarose gel electrophoresis and this makes sense to me because it is small and experiences the least friction because of its supercoiled structure.

Linear DNA migrates faster than the circular form. I didn't understand why exactly. Shouldn't the circular one be considered to be smaller than the linear, and thus quicker?


texts: I am new to this community, and I was wondering if insects could metabolize poisons. I'm not sure if I use the correct concepts, I simply wonder if insects can get rid of non-lethal doses of insecticides, and live as they have never been exposed at them. I know that human liver does this task for us, but I don't know if insects have this mechanism.


texts: Identify this extremely tiny white bug please!

texts:
I have noticed these extremely small, hard to notice with naked eye bug for about 3 nights now. Twice on my body in the kitchen and once on my thumb in my living room. I managed to catch one last night from my living room which has an area rug near a mattress, coffee table and couch. I managed to put it in a small 2 inch box with white lid. Today it seems little brownish and inspected it under a microscope.
First  picture is of the box size to put some real world perspective on the actual size.

Second pic is of the bug lying on the white lid, doesn't seem to be even 1.5 mm.

Third and fourth pic is from the microscope(150x), I had to move the bug so I might have squished it a bit.

We are getting bite marks and are almost convinced that this bug is the reason as we never had a bug problem ever. The only other thing we noticed is a silverfish in our living room but not sure if that can cause these bite marks.


texts: What is the difference between a circular and a cat's-eye (slit) pupil?

texts:
I've been to local zoo the other day and one lizard caught my attention: its pupils are circular, which, I thought, is not usual for reptiles. Turns out it is, but now I can't find any explanation on why some animals have one kind of pupil and others have the other. Lizards can have both, and so can snakes. The only difference I have found is that circular pupil can't shrink quite as much as a cat's-eye pupil, but that hardly explains why circular pupil even evolved in the first place as I don't see any advantage to it.

Ideas?

P. S. Fish only have circular pupils so that shape is older, right?..


texts: How much force can connective tissue withstand?

texts:
I have been studying a 3D anatomy model. Based on visual observation,  it doesn't look like the bones would be able to stabilize themselves at all without the connective tissue like ligaments. In the model I have been studying, i've noticed that all the ligaments are clustered around joints or areas where the bones connect and it looks like it they act as a kind of glue to in essence keep the joints intact. However, I don't really understand how much force connected tissue must withstand on a regular basis.

How hard is it to keep bones aligned and confined enough that the bodies overall shape remains pretty constant? Is this the role of connective tissue? if so, how much force does such tissue need to withstand on a regular basis?


texts:
It has a body which is divided into three parts:

The head, which is small, with a black, needle-like structure on the tip which I think is the mouth.
The upper body, which has a pure white color that is softer than the lower body.
The lower body, which is hard, has some blacks spots on the rear end with a yellow spot on the very tip and, compared to the upper part, has a clouded clear white color.

It moves very strongly when touched, but not that much.

My classmate found this when he opened a leaf from a small plant, thinking that it was a butterfly pupa because it was covered with a silk like cover but very thin to be compared to a butterfly cocoon.

Larva pictured here:


texts: Fisher's Fundamental Theorem of Natural Selection

texts:
Ronald Fisher discovered what he, with humility, called the Fundamental Theorem of Natural Selection. This theorem says (in its modern terminology):

  The rate of increase in the mean fitness of any organism at any time ascribable to natural selection acting through changes in gene frequencies is exactly equal to its genetic variance in fitness at that time.

As I understand it, it sounds alike the standard equation that we learn in the first class of Introduction to evolutionary biology

$$R = S \cdot \frac{V_G}{V_p}$$

In words: the response to selection equals the selection differential times the genetic variance of the trait under consideration divided by the total phenotypic variance of the trait under consideration

But how can we prove/demonstrate that Fisher's fundamental theorem of natural selection holds true?

I don't ask for empirical evidences that support this claim but for a theoretical/mathematical proof/demonstration of this claim.


texts:
I'm am refurbishing some old CO2 incubators. I would like to test the precision of the CO2 sensor. There is a sample port on this incubator.

What sorts of  methods are commonly used to measure CO2 in these incubators?

Strangely, the manufacturer of the incubator makes no recommendations.

I need to be able to report the measurement as a percentage.


texts:
This was found off the coast of Ireland by a friend of mine. The running gag is it's some kind of fetish or totem and should be immediately discarded, but we're interested in whether it's perhaps a coronal section of a fish skull, a bivalve or something else entirely. Many thanks to anyone participating!

Attachments :

Image-1

(higher resolution)

Image-2

(higher resolution)

Image-3

higher resolution


texts: Do mosquito repellent sprays work on all insects?

texts: I would like to know the mode of action of mosquito repellent aerosols. Are these specific to mosquito or are other insects affected too?


texts: Formulation of Biomass reaction for metabolic model

texts:
What are some good review articles that could help me develop basic knowledge regarding biomass equation formulation?
I read this paper titled biomass objective function, but it only gives a general idea, and I'd like to learn more about the specifics of the process.


texts: What does "delineate" mean in this context?

texts:
I was reading a Scientific American story, “Controversial Spewed Iron Experiment Succeeds as Carbon Sink” (by David Biello), when I came across this sentence:

  “The problem for scientists is that oceanic waters tend to mix, which
  makes monitoring and delineating an experiment in the ocean
  challenging.”

I'm wondering what “delineate” means in this context. I think I grasp the general idea of this sentence, but it is the exact meaning of the word that has been troubling me.

Could someone kindly enlighten me on this?

Thanks!


texts: Was there a time in Earth's history when some animal life existed on land but humans could not have breathed?

texts: I understand that higher oxygen content allowed insects and arachnids to grow much larger than today and I wonder if this additional oxygen would have been toxic or unhealthy for modern humans?


texts: Which Enzymes are Responsible for the Biodegradation of Beta-endorphin?

texts: Which enzymes are responsible for the biodegradation of the endogenous opioid peptide, beta-endorphin?


texts: Given the (non-identical) DNA sequences of two men and the knowledge that the second man is either the father, brother, or son of the first man, is the DNA useful in determining which of these three he is?  Even the slightest probabilistic indicator would be useful.


texts:
Looking at most chordate phylogenetic trees, it seems that we usually have something like this:

  ,================= Lancelets
 =| ,=============== Tunicates
  \_|
    \_______________ Craniates

So, my question is, what do we think the common ancestor of tunicates and craniates looked like? Did both clades evolve from a lancelet-like ancestor, with the tunicates becoming sessile after the divergence, or are craniates descended from a tunicate-like ancestor?


texts: Molecular biology - fundamental questions

texts:
Basic Gene, Chromosome, Genome, Protein - how are they ordered?

Genes make up Chromosome, and Chromosomes make up a Genome...

So, where does Protein come into play?

What do you call Genes that are spliced together to form something new?

What do you call a variable inside a Gene?

Thanks.


texts: What exactly is this plant resembling Conyza?

texts:
This plant grows on my balcony in Vienna, Austria. It gained most of it’s current height (30-35cm) during the last 2 weeks. Before I didn’t notice it.

It is covered with tiny white hairs. I conducted a couple of tests. They never stung.
The leaves are toothed (I believe “serrate” is the official terminus for this type of edge).

From a central leaf vein, more veins spread out in a manner that seems somewhat irregular to my untrained eye:

Edit: Now, in July, that is about 2 months later, it bears flowers.  Furthermore it is about 3 times taller. I believe there were seed heads, which have been blown and washed away. All of this would fit Conyza mentioned in the comments, but the shape and density leaves  appear to differ from C. boranensis or C. canadensis.

Edit: now, still July some seed heads have reappeared


texts: I live in Illinois and this came running across my living room floor.  After I stopped freaking out, I threw a bowl over it and called someone to come get it.  It was about 5” across.  My son thought it was a wolf spider but I didn’t think they got that big.  I hope someone can help to identify it.  Just the thought of there being more around is making me want to book a hotel!


texts: Why are there so many different humans yet chimpanzees are just chimpanzees?

texts:
There are two species belonging to the Pan genus (Pan troglodytes and Pan paniscus). That's just two.

I mean, humans have changed radically since we split from chimpanzees, we have Australopithecus afarensis, africanus, anamensis, Paranthropus robustus and boisei, Homo erectus, habillis and so on.

A chimpanzee fossil that is 2 millions years old should be pretty different from a modern one, why aren't they considered another species?


texts: Understanding of the saturation function in the Monod-Wyman-Changeux Model

texts:
I am reading Mathematical Physiology, Sneyd. I am a undergraduate mathematician interested in pursuing the field, so forgive me if my terminology is off. In this example, the writer considers a protein with two binding sites. The subscript $i$ indicates the number of bound ligands.
This expression, called the saturation function, appears on page 18:

$$Y = \frac{r_1 + 2r_2 + t_1 + 2t_2}{2(r_0+r_1 + r_2 + t_0 + t_1 + t_2)}$$

Where, $r_i, t_i$ denote the concentrations of chemical species $R_i, T_i$ respectively.
It looks like the weighted average of the ezymes that have occupied binding sites.

The fact that $t_0, r_0$ do not appear in the numerator suggest that it is the saturation of enzyme binding sites,  the $2$ in front of the $r_2,t_2$ indicates that the enzyme with both binding sites occupied is "double concentrated". The two on the denominator indicates the number of available binding sites in the enzyme. Perhaps, if we were considering an enzyme with three binding sites:

$$Y = \frac{r_1 + 2r_2 + 3r_3 + t_1 + 2t_2 + 3t_3}{3(r_0+r_1 + r_2+ r_3 + t_0 + t_1 + t_2 + t_3)}$$

  Would this description be correct?


texts: Sensory neurons, interneurons and motor neurons - recognizing the type of neuron at microscopy images

texts:
Is there a simple way to distinguish between sensory neurons and interneurons and motor neurons at the microscopic images?

I read a little bit about Open Connectome Project. Is there a possibility of automatic (computer - algorithmic) recognition of the aforementioned types of neurons?


texts: Is Einstein's mass energy equivalence ($E=mc^2$) relevant to biological systems?

texts:
I'm more than 100% sure that the kilograms I eat don't get directly converted to feces and urine.

I'm sure some of it goes to regenerating tissue that is constantly being disposed as well, and maybe some of it is  also being exhaled.

But I have a feeling that $E=mc^2$ might have something to do with the disposal of ingested kilograms.

We are constantly radiating electromagnetic waves in the nonvisible spectrum, we generate heat, we generate chemical bonds, all of these processes can convert mass to energy.

So I was wondering if $E=mc^2$ is relevant to biology?

Thanks.


texts: What are the differences between internal organs between sub-saharan Africans and Northern Europeans

texts:
Lets take as examples a typical Norwegian and a typical Nigerian.

In terms of human anatonomy the outer differences are more obvious e.g. (on average)

White skin vs dark skin
Pointy nose vs broad nose
Thin lips vs thicker lips
Straight hair vs tight curly hair
Different skull shape
Height differences
Different colour eyes or eyelids.

In fact there is almost a difference in every external organ.

There are also some invisible differences such as propensity to sickle cell disease.

But what I hear less about is the differences (in general) between internal organs between populations. Some people even suggest that differences are only "skin deep" between human populations. Which I think goes against evolutionary theory. As why would natural selection stop at skin level? Also, there is a lot of research into skeletal differences but that's easier to do since we can look at a skeletons.

Therefor it seems fairly logical to assume that there would be fairly apparent differences in internal organs between these populations. (I hesitate to use the word 'races') i.e. as apparant as different hair types, or different nose shapes.

I don't mean that one population will have 3 kidneys for example, but I would expect that there would be an obvious shape or size difference between most, if not all internal organs, just as there is a shape, colour or size difference between most external organs.

Is there some research done on this, e.g. a catalogue of differences in internal organs morphology between different populations? Or is it taboo to even ask such questions perhaps?

Edit: One might say, "how would anyone know? Or care?" But, for example, a heart surgeon might find they need different sized instruments dealing with different people. Or surgeons from different continents might compare notes on anatomy. And anatomy textbooks based on just one population might not be representative. Surgeries working on one "race" might not work on others. e.g. if the heart wall was thinner or the colon was longer.


texts: How long do Ziehl-Neelsen stained samples keep?

texts:
I have acquired TB slides from my city's health center that are supposedly acid-fast bacteria (AFB) positive. However, when I took a look at it, I see basically no carbol fuchsin stains.
They were individually neatly folded in paper. When I opened them, the stains were slightly wet with immersion oil, facing down. So far, so good (page 6). I've been later informed that these samples were prepared Q1 2019. Based on my research, the staining solutions themselves last up to 12 months (page 33). I can't find any data on how long a stained sample would keep though.
Do they decolorize over time? I expected the AFB to be bright, or at least slightly pink, but I see no such thing. I do see bacilli, though all of them are nearly transparent/methylene blue in color.

Here are some sample images. The first 2 are how I expected AFB to look like, while the next 2 are what I captured (and I think should contain AFB). The last pic is a 10um/div calibration slide for reference.


texts: How do I know which alleles the parents have?

texts:
I have the following assignment where I am to look at the "tree" (not sure the english word) and assign whether or not they can be autosomal dominant or recessive as well whether they can be X-linked recessive.

My way to try and complete this assignment is by drawing a punnet's square but I quickly run into some confusion. When I draw my square, I know that is I'm checking for autosomal dominant, then I would draw the mother as A'a, the A' denoting the sick dominant allele. What I'm not sure is this: Can't I also draw her as A'A'? That would also mean she would be autosomal dominant but with 2 sick alleles. What about the father? Do I draw him as Aa, aa or AA? I'm a bit confused here!


texts: Seeing with one eye, why intensity doesn't get half?

texts:
Today I just closed one eye(for finding blind spot), and as usual some of the visual field is lost, but I wonder why is not intensity of light(brightness) reduced to half?
Shouldn't it be since our brain is now getting only half impulses?

Does our brain instantly reduces the threshold of rods and cones when one of the eye is closed?


texts: What is the duration (Life") of pfu turbo DNA polymerase AD. I am trying o Amplification a 3.3kb fragment and the PCR schedule is 6 hours long. The manufacturers notes just specify that its activity remains 94-99% in 1 hour at 95, nothing more.


texts: Gender and age-specific mutation rate in plants

texts:
Background

General concept

According to Cochran and Harpending (2013), mothers transmits on average a number $x$ of new mutations to their offspring. This number $x$ is independent of the age of the Mother. Fathers, however transmit a number of new mutations to their offsprings that is very much dependent on the age of the father for developmental reasons. In short (and probably poorly stated due to my lack of knowledge in physiology), spermatogenesis is a continuous process that occurs during the lifetime of the individual while the creation of ovules occurs once and are then stocked.

Human example

According to Kong et al.(2012), in humans the mother transmit on average $15$ new mutations and the father transmit on average $25 + 2(g-20)\space\space$ new mutations, where $g$ is the age of the father. For example, a 30-year-old father transmits $25 + 2(30-20) = 45\space\space$ new mutations. (This approximation holds only for men older than 20 years).

Question: How about plants?

Do you think that in plants too, male and female organs (or individuals for (gyno/andro)diocious species and eventually sequential hermophroditic species) transmit a different number of new mutations for similar developmental reasons?
Do you think that in plants the number of new mutations is age-dependent in males but not in females alike in humans?
Do we have any estimate of the sex and age-specific number of new mutations transmitted in plants?


texts: Does prokaryotic transcription have activators / enhancer regions involved?

texts: I am designing a biosensor, and I need to know whether prokaryotic transcription involves or can involve (if a gene needs to be regulated) enhancer regions. Also, where are enhancer regions located (how far away from the promotor), and when isolating a promotor region, how do you make sure you are also isolating these enhancer regions?


texts: Why did viruses evolve in the first place?

texts:
This question might seem kind of strange, but it's something I've been chewing on for ages, and I can't really think of a good answer.

Viruses just seem to be floating around passively until they encounter a host cell. Then they enter the host cell, wreak havoc and use the host cell machinery to make more copies of themselves. Then these copies float around passively, until they find host cells.

So what's the point of all this? Infecting the host and causing so much trouble for the host, I mean. The only thing I could think of was something like the "selfish gene" hypothesis, i.e. the genetic material of the virus wants to make as many copies of itself as possible, and in order to secure the machinery for replication, it must infect a host cell. But it's not a very satisfying answer, somehow. All other living organisms at least have their own replication machinery. Then what kind of organisms are viruses? (Are they even organisms?) How and why did they evolve and stay around on the earth for so much time (till the present), if they depend on hosts for their replication?


texts: This fruit was spotted in Kochi, India on several occassions. Nothing else is known except the fact that it seems to be irregularly distributed through Kerala.


texts: Can the same target gene be regulated differently by the same transcription factor under different conditions?

texts:
I'm very new in biology and doing more computational analysis. I'm confused with the type of interactions between Transcription Factors (TF) and target genes.

Is it possible that the same transcription factor interacts differently with the same target gene under different conditions?

e.g., TF1 up-regulates Gene1 under condition 1 while TF1 down-regulates the same gene Gene1 under condition 2
Does the above example take place in biological systems?

I can only think of different TF complexes which are regulating the gene Gene1 under different conditions with different effect. However, it would be great to know if, in case TF1 does not participate in any TF complexes to regulate Gene1 under certain conditions, it is then possible that "TF1" regulates Gene1 differently under different conditions?


texts:
Outlet of digestive system is present at back of the body but its digestive system at front.

Outlet of urinary system is present at front of the body but its system present at back.

Why do humans have digestive system present at front and kidneys back?


texts: What is difference between "Syngonium" & "Pothos"?

texts:
They both look the same to me, but they are different from each other.
Please help me in figure out the difference in both of these species.


texts: Why do food items and medicines expire after sometime?


texts:
Assuming that intelligence has a genetic component,

• do we know which genes contribute to it?

and, if so,

• can we predict intelligence from genomic analysis?


texts: Do females retain oogonia after puberty?

texts: Oogonia are the precursors of oocytes in females present during embryonic development. I was wondering whether these stem cells are still present in the ovaria at puberty?


texts: What are some features that do not make an individual better than others without this feature?

texts:
If a mutation occurs so that this allele gives a noticeable feature that is present in this individual but absent in every other individual and this feature is of no benefit or detriment to the individual, I was thinking that this mutation will not make the individual better soothed to the environment or worse and so the gene may not die out but be passed from one generation to the next generation.

If this is so, I thought, there should be many of such “useless” gene present in today’s world. Other than the appendix (which has no function in humans) and subtle differences like eye color, head shape ( not too severe ones but like the ones we see everyday - different heads), which other examples exist?


texts:
In infants, rennin helps in digestion of milk. Pepsin is also present in their stomach.

Why do infants need rennin for milk digestion, at the first place? Why does pepsin not act on the milk proteins in infants? Does the production quantity of rennin play a role in inhibiting the action of pepsin?