texts: How can Southern blotting be used to establish gene copy number?

texts:
I am reading a paper on a certain marine microorganism that can eat alkanes and therefore might be useful for cleaning up oil spills, etc. This sentence struck me as odd (although I am sure that the answer is pretty simple):

  Using the same probe, Southern blotting analysis showed that there was only one copy of alkB1 in the B-5 chromosome.

I realized that I don't know how Southern blotting can tell you about copy number. Can someone help me on this?


texts: Does bright environment strain eyes more than dim?

texts:
I'm trying to figure out how to modify my working conditions so that I can program longer without harming my eyes. Because doing so experimentally hasn't given conclusive results so far, I decided to ask for studies in this area.

Does looking at a bright screen in a well lit room strain eyes more than looking at dark screen in a dark room for prolonged periods of time? Or is there a middle ground somewhere in-between that is most harmless? Or is it a combination of contrasting screen/background?

I'm not asking for medical advice here. I already went to several doctors and they gave me different, sometimes contradicting answers, so I'm just looking for research.


texts: What happens to the complementary base when the other undergoes a base substitution mutation?

texts: From what I know only the base pairs A and T/U, or G and C can occur due to hydrogen bonding. So if a base substitution mutation occurs, say an A is replaced by a C on the strand, does it affect only one of the strands on the DNA or does it changes the base pair entirely? Thanks.


texts: Expressing bacterial proteins in mammalian cells

texts:
Does anyone have experience/knowledge of expressing bacterial (or other microbial) proteins in mammalian cells? I am interested in this for a project where we are trying to introduce a new enzymatic activity in human cells. I have been looking for examples in the literature, but haven't found anything so far.

I can imagine that various problems might arise. Presumably transcription and translation should not be a problem; but I can imagine the protein may not get sorted/localized properly, or might not be properly degraded and so could  accumulate to toxic levels ...  or what not.

Any advice or pointers to literature would be much appreciated!


texts: Is there any example of genetic mechanism of delayed onset toxic effects?

texts: We know that exposure to many toxic chemicals during embryonic development may show toxic effects later in life. It is called Developmental Origins of Health and Disease (DOHAD). Most of the mechanisms reported behind these kind of toxic effects are epigenetic. I could not find any genetic mechanism in the literature. Is there any example of genetic mechanisms behind DOHAD?


texts: How do poikilotherms thrive in a wide range of core temperatures?

texts: What is it about the metabolism of a poikilotherm that enables them to adapt to the surrounding temperature?


texts:
My book keeps giving different indicators as to whether the promoters are on the coding or template strand.

It says the -35 region in prokaryotes must be on the coding strand. It also mentions, that the -10 and -35 regions are binding sites for RNA polymerase.
It also says that CAAT and GC, unlike -35 in prokaryotes, can also be on the template strand. Which implies that they are still most common on the coding strand. And then it shows me a figure, where a promoter sequence is shown in the template strand, with the transcription complex attached.

All the sequences are written 5'-TATAAA-3' (for example). This also implies they are on the coding strand, since the template strand will then be 3'->5' which is the direction that transcription happens in.

Obviously I'm confused, and hope someone can clarify this. In which strand can I find the promoters? Does stuff act on the promoter sequence itself, or its complementary sequence? If the promoter can also be on the other strand, should it be reversed?


texts: Why can all animals swim in water without learning to swim but humans cannot?

texts:
I had a question since I was a child. I was always curious about the fact that all animals can swim in water. They don't need any training or to learn swimming. But humans need to learn to swim. Why ?

I am a technical person and not in biology after my 10th year in school. Can anybody please shed some light on this question?


texts: Did the Britons 100 years ago have different intestinal flora and fauna?

texts:
Note: this is not a question about history, but about human digestive system over time :)

I know a lot of colleagues who traveled for business trips to India. All of them caught  terrible diarrhea there, in spite of keeping all the rules related to use of reboiled or canned water only, eating only peeled fruits, not eating the street food etc.

My question is: how did the millions (or hundred thousands, I am not sure with the amount) of Britons survived in India during the time of the British Raj 1858-1947?

Did they have to keep the same safety dietary rules as the contemporary Westerners all the time? (I cannot see this as technically possible...)

Were our intestinal flora and fauna different one hundred years ago?

Was the hygiene level and quality of water much lower in Europe then so coming to India was not such a biological shock? (Well, I would believe this in the 1800s but not in the 1900s...)

Or did just some of them die and the rest got accustomed?

EDIT:

I am aware that there is an initial shock for your body when travelling to a very different area generally. However, the Indians (and other Asians) can easily drink the tap water in most of the EU countries and eat the street food, which is not valid vice-versa. So there must be some difference.


texts:
I was reading this National Geographic article, 50 New Spiders Discovered In Australia when I became confused by the two trapdoor spider species photographed. I looked up trapdoor spiders and looking at pictures, they all seem to me to have five pairs of legs. I know spiders have eight legs; can someone tell me what am I missing here?

Ctenizidae:

Euoplus:

Cork lid:

(OK, so I found out that the things next to the mandibles are pedipalps. How are they different from legs on these beasts?)


texts: Cadmium Poisoning and Toxicity Mechanisms

texts: Is anyone aware of the toxic mechanisms of specific instances in which cadmium ions can interfere with cellular functions resulting in acute cadmium poisoning?


texts: How is insulin transported in vivo in mammals?

texts: What is the mechanism for transport of insulin in mammalian cells?


texts: How do biologists determine the parents of a child

texts:
I am not well-versed in biology so this question might be wrong. As far as I understand meiosis, two germ line cells with 23 chromosomes each (one cell from the father and another from the mother) combine and after meiosis we get recombined chromosomes from the haploid cells with 23 chromosomes that will develop into an embryo. So, the child has different chromosomes than the ones of his father and mother. Then how can we know, by analyzing the child's DNA, who are the parents?

My simple question comes, in part, from this video about meiosis

I apologize for any errors.


texts: Why does the head swell after getting hit by something hard? What is the liquid that forms after impact?


texts: Is life expectancy linked to intelligence in animals?

texts:
For example, animals that live only a few days or a few years are often not very intelligent. In contrast, the most intelligent animals seem to live longer.

Is this true? Are there any studies to prove or disprove this statement?


texts: Removing bacterial contaminants from resin

texts:
We have a few Strep-tactin columns that had some growth in them and we would like to regenerate the columns back since the resin is quite expensive. Basic goal: remove the brown stuff.

So far, I've killed whatever living material there is with 20% EtOH and 0.5 N NaOH. After cleaning out the columns with Tris Buffer, I've tried regenerating the columns with Buffer with HABA and the resin is a bit redder than before (typical reflection of good regeneration). However, rinsing out the columns again still leaves behind a brownish color. There is also a good deal of black particulate in the resin.

I'm curious what methods exists to clean out a contaminated column.


texts: Are primary lysosomes same as vesicles budded off from golgi bodies containing hydrolyzing enzymes tagged with mannose-6-phosphate?

texts:
SO, as far as I understand, lysosomal hydrolyzing enzymes are first synthesized as proteins in rough ER and then they are budded off from the ER. The vesicles containing those proteins reach cis golgi and then they are properly folded to proper hydrolyzing enzyme but they are tagged with mannose-6-phosphate at this point, so they font have the ability to hydrolyze molecules just yet. In the mean time, some molecules can be engulfed by the cell and and these enter the cell as a membrane bound vesicle (endosome) containing proton pumps in its membrane which maintains an acidic environment inside the vesicle (which matures to late endosome). Vesicles containing hydrolyzing enzymes now move to those late endosomes and fuse with them. The low pH cleaves the mannose-6-phosphate tag from the enzymes and they become functional thus late endozome matures to lysosome.

The definition of primary lysosome says it is that lysosome that directly buds off from the golgi bodies and secondary lysosome is that lysosome which gets formed when primary lysosome binds with a vesicle and hydrolyse its content.

So are primary lysosme and those vesicles same?


texts: What is the 'job' of the byproduct water in the Electron Transport Chain?

texts:
I understand what happens in the Electron Transport Cycle, but I fail to understand that after Oxygen has accepted an electron, it forms water, but why? what happens to the water? I can take an educated guess but again its a guess.

Does it then react with ADP?

Thanks in advance! I'm doing an animal welfare course and as part of it I need to study basic biology.


texts: Designing genes with DNAWorks: Maximum nonzero score?

texts: I'm designing a gene in DNAWorks, and I'm unable to find a set of conditions that gives an "overall score" of zero (which is what I normally insist on). People that have used DNAWorks: what's the highest nonzero score you've been able to successfully assemble?


texts: Focusing your attention on an area within your body, what effect does it make?

texts:
When I focus on tactile signals from a certain part of my body for a while (e.g. for one minute), this part of the body will usually become warmer. For example I can do that with a certain finger or with my palm, or with a certain spot on my forearm or on my leg, etc. Basically any part of the body.

From what I heard, when you focus on a spot within your body, the blood flow increases there. But what is the mechanism exactly? How does it happen? From what I found in neuroscience, sensory system only sends signals in one direction, from receptors to the brain. Attention is something happening within the cortex. What processes exactly take place when you focus on a certain body area? Is there a "response" signal from the brain to the area? How does it increase the blood flow?

My interest actually comes from my discovery that using my attention I can do surprising things within my body. I can relieve pain in most cases, it only takes 5-15 minutes of deep focusing. Once I successfully used this technique to relieve itching sensation from a minor skin inflammation on my leg, and after that the inflammation has gone away completely by the next morning. So I assume that focusing attention initiates certain processes in the body. I'm researching to find out what exactly these processes are.


texts: Runs of homozygosity - degree of inbreeding and disease associations

texts:
Been reading recently about methods to determine how inbred a particular person is by measuring their "runs of homozygosity." Loosly, these are defined as regions of the genome (typically >1Mb) where the person is homozygous for all polymorphisms, suggesting their parents were identical for this region. If a person has 'many' of these regions, it suggests their parents were closely related.

A study in 2015 [1] found some evidence that people with more regions of homozygosity had higher risk of heart disease.

My question firstly relates to the amount of homozygosity you might expect in a 'normal' out-bred person, compared to an in-bred population (e.g. small community), and then to 'extreme' examples of relatedness (parent/child offspring). In my searching I didn't see any cut-offs, if they exist, or whether this is even the right way to be thinking about it. And secondly, just how bad is it to have these runs?

Christofidou P, et al. Runs of Homozygosity: Association with Coronary Artery Disease and Gene Expression in Monocytes and Macrophages. Am J Hum Genet. 2015; 97:228–237. PMID: 26166477.


texts: Is it comfirmed that Alzheimer's is a diabetes of the brain?

texts:
I read in this New Scientist report, that the mental decline during diabetes may be an early stage of Alzheimer's.  The hypothesis was based on a study with 20 rats.

Has there been any follow up research? Is Alzheimer's such a slow disease that this is will be remain hypothetical for a while?  Are there any other links between diabetes and Alzheimer's that can point in either way?

Or has research even confirmed (or refuted) another weaker hypothesis true, namely, the mental decline during diabetes and Alzheimer's have a common cause?

Many times newspapers say this or that is being research and we will know one day whether this is true or false; but the same newspapers hardly ever do follow up reporting.  So this is why I am asking this here.


texts: Why is a screening process required in selection from a genomic DNA library?

texts:
After the process of construction we go for screening process of selecting a recombinant host. Which includes:

DNA hybridisation
Colony hybridisation
Random primer labeling
Nucleotide autoradiography

These techniques are very tedious. So instead of all these tedious process why cannot we just grow them in a minimal media to get the recombinant host and to check which protein is formed?


texts: Is this may-flowering grass an Echinochloa (barnyard grass)?

texts:
There's a grass growing in my thyme pot on my balcony, that's currently flowering (end of May, Paris region, France, southern exposure, windy conditions), and I'm wondering what species it is:

Here are a picture where details of the flower and leaves may be more visible:

I tried to search using my old determination key for French flora (G. Bonnier / G. De Layens), and after much hesitations, I guess it could be what is called "Oplismenus Grus-galli" in this book.
Internet tells me it is now called Echinochloa crus-galli. The base of the plant indeed has a similar way of growing, and the flowers are a bit similar.

Does this look plausible? Do you see a better match?

Can I use the seeds when they are ripe (for instance to put in home-made bread)?


texts: Do High Triglycerides Invalidate Tests for Infections?

texts:
Blood donation websites tell you to avoid eating fats a few days before the donation, because when there is a lot of fat in the blood, they can't test for infectious diseases and must discard the blood.

Does that mean that if you have, say, high triglycerides, the result of an infection disease blood test will be invalid? Say you test syphilis, HIV, etc. If at the same time you get a result of high triglycerides, does that mean the results of infectious diseases can't be trusted?


texts: What is the difference between muscle contracture and muscle rigor

texts:
My text says muscle contracture is a state of sustained muscle contraction due to depletion of energy. And muscle rigor is the stiffening of muscles when they're depleted of energy.
So, what exactly is the difference between these two?


texts: Why lactate inhibits growth (or enhances death rate)?

texts:
Extracellular lactate tends to inhibit cellular growth or enhance cell death. This happens in the vicinity of tumors and in cell cultures.

See for example this reference: Ozturk, Sadettin S., Mark R. Riley, and Bernhard O. Palsson. "Effects of ammonia and lactate on hybridoma growth, metabolism, and antibody production." Biotechnology and bioengineering 39.4 (1992): 418-431 (available here: https://www.researchgate.net/profile/Mark_Riley5/publication/227705703_Effects_of_ammonia_and_lactate_on_growth_metabolism_and_antibody_production/links/540e0bcb0cf2f2b29a3a765a.pdf)

What is the mechanism behind this effect of lactate? Why lactate has these negative effects?


texts: Species with reproduction barriers that can both reproduce with a third species

texts:
To start with, I do not have a sound knowledge in biology or any formal education in the area.

I was told that one of the definition of a species is a reproductive barrier, which means that if two animals can't reproduce, they are of different species. The barrier can be either the inability of the sperm to fertilize an egg, or a physical trait that inhibits reproduction, e.g. a cricket species that has a different mating song than another species or two species of flies, one that mates on yellow flowers, and the other on red flowers.

But what happens when, while two species can't reproduce, but there is a "chain" of "intermediate" sexual partners that can produce reproductive connection step by step. Like 6 degrees to Kavin Bacon, but with animal sex.

I'll try to explain with an example:

A Great Dane and a Miniature Pinscher dogs can't mate due to obvious size differences. But The Pincher can mate with a German Pincher (a slightly bigger breed of Pincher), which can mate with a Doberman Pincher. And the Doberman can mate with a German Shepard which can mate with a Great Dane.

I've also heard that such things happen with birds and crickets, where there is an original species, from which evolved several other, and while the original species (which still exists) can mate with all the new species. Some new species can't mate with some, or all of the other new species.

How are such species are defined, and at what point dogs stop being dogs anymore?


texts:
Can developing twins further divide and subdivide and become identical quadruplets or octuplets or...?
Can twinning be induced, either in utero or in vitro?
Might it be possible to just keep harvesting a few cells off the original clump indefinitely and making an unending stream of identical embryos for implantation in a surrogate uterus?


texts:
I read somewhere that a man dies if he is isolated from natural electromagnetic fields and waves. (I imply fields of radio frequencies and below.)

Is it true?


texts: Why are the posterior and anterior inferior temporal cortex called area TEO and area TE respectively?

texts: I don't understand why you would call them that. How did these names originate/where did these names come from?


texts: What could account for an apparent loss of mass at death?

texts:
An interesting tidbit floating around the internet these days is that Dr. Duncan MacDougall apparently weighed people shortly before and after death, and found an average of a 21 gram discrepancy, to which he attributed to be the soul departing. As we all know, this certainly can't be the right explanation.

Putting aside likely extreme bias and instrumental/experimental error, is there any bodily process at death that could potentially explain a small decrease in observed mass?


texts:
According to Wikipedia:

  Meiosis is a specialized type of cell division that reduces the chromosome number by half. This process occurs in all sexually reproducing single-celled and multicellular eukaryotes, including animals, plants, and fungi Because the number of chromosomes is halved during meiosis, gametes can fuse (i.e. fertilization) to form a diploid zygote that contains two copies of each chromosome, one from each parent.

So it means that a haploid plant body will give rise to either a male sex organ or female sex organ that produces gametes to form zygote thus completing the alternation of generation.
We also know that chara a monoecious plant can be dioecious, which means that haploid plant body is producing both antheridia and archegonia which produce gametes by mitosis.
Coming to my question, "HOW CAN A PRODUCT OF MEIOSIS BEFORE FERTILISATION BE BISEXUAL?"
Does this implies that reduction division is not responsible of sex differentiation? If yes then what is responsible for sex differentiation in plants like chara where a haploid produces both gametes ?
Explanation will be appreciated


texts:
We are having trouble with agarose gel electrophoresis. It used to work a couple of months ago but now the ladder always look smeared. We switched the components (1x TBE, 100bp ladder, different type of agarose and voltage) and equipment. We also tried 1.2%, 1%, 1.5% and 2% agarose.

I would appreciate it if someone can help us.


texts:
Going by the assumption that stress eventually triggers a flight/fight response, and the subsequent realization that flight/fight puts the body in a system of readiness to use it's available resources (mental, physical).

Does it make sense to think that stress physically ages a person? I am specifically referring to characteristics identified with aging such as  bleached hair, telomere shortening, wrinkles around the eyes, etc.


texts: Can sealed epiphyseal growth plates theoretically be restored via epigenetic or genetic methods?

texts: I know that epiphyseal growth plates seal up once people become young adults and that it is currently impossible to restore them to actively produce new bone growth but, is it theoretically possible via genetic or epigenetic means to reactivate them to produce new bone?


texts: What is the base cancer rate for an arbitrary carcinogen?

texts: Are all carcinogens equally potent? Is the relationship between dose and probability of cancer roughly equal, or are there some carcinogens that provoke cancer significantly more than their cousins?


texts: Why are there not effective pharmaceutical treatments to prevent weight gain?

texts:
Hunger is caused by signals from the brain, so is there a way to suppress the signal of hunger in the same way we suppress the signal of pain with painkillers?

If people felt less hungry, they would eat less and find it easier to lose weight, so why aren't there pharmaceutical hunger suppressants yet?


texts: Do histones constitute the largest proportion of the protein in chromosomes at mitosis?

texts: Do histones contribute more (by mass) than non-histone proteins in the chromosomes formed during mitosis?


texts: What is the average speed of human sneeze?

texts:
I sneeze a lot, at various times and various "volumes", and often wonder about the speed of the sneeze itself, i.e. the speed of the air coming out of the nose while sneezing.

What is the average speed of that, in humans? Are there any records for such a thing?


texts: RNA-Seq library construction challenges: the biases of RNA fragmentation vs cDNA fragmentation

texts:
I recently watched a presentation on RNA-seq that covered some of the choices one can make along the way, and I didn't fully understand one of the choices in particular.  Near the beginning of the process, you can choose a fragmentation method (e.g. RNA: nebulization, hydrolysis; cDNA: sonication, Dnase I treatment). Each fragmentation method is biased in its own way, and the goals of the study may influence the choice of method.
I didn't fully understand the reasons for the characteristic biases (how do they happen?), and when to choose one method versus the other (which methods work best for which goals?).  Put another way, what are the mechanistic explanations for the characteristic biases that result from each method, and what is the significance as far as downstream processing and associated challenges?
Edit:
The heart of this question is about fully understanding the particular choice of when and how to fragment.  The reason I have not accepted an answer, yet, is that the answers provided so far address the mechanism part of the question, but not the ultimate reasons for choosing one versus the other.


texts:
At school we're told that the receptors for smell (olfactory receptors) are present in the Schneiderian membrane. But I've noticed that I'm only able to detect smells only while I breathe and not when I hold my breath.

I even tried an experiment to confirm my observations and the results were positive. I placed an open bottle of really strong perfume fairly close to my nose, and lightly inhaled. I could easily detect the smell. But as soon as I hold my breath I'm not able to smell it anymore, even though I placed the bottle right under my nose I wasn't able to smell anything. Immediately I moved the bottle away, walked into another room and took a breath, and the smell of perfume was so strong it made me choke.

I guess this 'experiment' of mine contradicts what we've been taught. That Olfactory receptors present in the nasal passage simply pick up traces of molecules (in this case, perfume) and this is perceived as smell, since by keeping the bottle right under my nose the perfume would've already diffused into the air in large quantities and would've already entered the nasal passage, yet I was unable to detect it.

So my question stands, 'Why is it that I can only detect smells if I breathe, and not when I hold my breath?'


texts: Carl Sagan's ideas on the self-extermination of technological civilizations

texts:
I've read (though I can't remember the source) that Carl Sagan speculated that intelligent life forms tend to evolve on various worlds, then exterminate themselves.

If true, then I'd like to learn more about this idea. Can anyone share any details on this? Do you know where I can read more about it?


texts: What prevents neurones from touching at chemical synapses?

texts:
The synaptic clefts are really small, but the neurones which they are between do not touch even against forces like gravity.

What really prevents them from coming into direct contact at the synapse, and also what would happen if they did come into contact?


texts: Can something like McDonalds be considered a life form?

texts:
"The current definition is that organisms are open systems that maintain homeostasis, are composed of cells, have a life cycle, undergo metabolism, can grow, adapt to their environment, respond to stimuli, reproduce and evolve." (Wikipedia)

Could McDonalds(or any other chain store) be considered a life form according to the current most accepted definition of Life? If not, what am i missing?

It evolves and changes over time; it reproduces by using excess Material to build new stores, it responds to outer stimuli by adapting to them; it grows to a point it is benefical; it starts to function sometime and will eventually stop; it autoregulates it self trying to maintain a stable state and it has a very complex metabolism

Thanks in advance


texts: What is the mechanism of labeling a DNA molecule with deuterated water?

texts:
I have seen a paper in which deuterated water was used to follow dividing cells. The assumption was that deuterated water will be incorporated into newly synthesized DNA molecules. Is there any direct incorporation of water in the replication process? Is there any proton exchange?

The paper describing the method can be found here:
http://www.pnas.org/content/105/16/6115.full.pdf


texts: Somewhere in evolutionary history homo started walking upright and became bipedal. You hear these hypotheses that, by walking upright, they could see better across the grassy savannas to escape predators, find food, find fellow humans etc. However, the most parsimonious way to accomplish looking farther across the grassy plains is by growing taller - much less adaptations necessary and hence more favorable from an evolutionary perspective. Other hypotheses say homo freed his hands to carry things. Quite fine, but some apes are known to carry around stuff. Moreover, walking on all fours increases running speed (you don't have to see far if you can escape faster) and apes climb trees better (what's a better place to hide from predators?). Hence my question: Why has bipedalism been favored in evolution?


texts: ID for red millipede swarm near my place

texts:
Location:Hyderabad,South India.
These worms usually come out when it rains,these worms are the most common ones any help in figuring out them,they come in groups too.


texts: Do fish increase or decrease pH of aquarium water?

texts: If I understand it correctly, aquarium fish produce NH3 as their waste product and CO2 due to respiration. Producing NH3 increases water pH due to its equilibrium with NH4+. Producing CO2 decreases pH due to its equilibrium with H2CO3 and its equilibrium with HCO3-. My question is: Which of these effects is more important in most common aquarium fish? Do fish increase or decrease water pH?


texts: Why is electroporation not the prefered choice transforming for Mammalian Cells (HEK)?

texts: I see a lot of folks using different techniques for transforming mammalian cell (specifically HEK) instead of doing electroporation like I see with E.Coli (bacteria). Is there a reason for this ?


texts: Inequality factor for similarity sensitive diversity

texts:
In a research article, Lou Jost has introduced the concept of inequality factor. The paper is "The relation between evenness and diversity", published in 2010.  Inequality factor allows an intuitive interpretation of the slope of a diversity profile. It corresponds to "the number of maximally uneven communities" is very intuitive.

I could not find the analogue of inequality factors in context of similarity sensitive diversity, for instance, Leinster-Cobbold diversity. Is there any equivalent notion of inequality factor for the similarity sensitive case? Could anyone suggest me some readings?


texts: Lost Ability to Regenerate Body Parts during the Transition from Amphibians to Mammals

texts: Why have higher-order animals lost the ability to regenerate body parts during evolution? Wouldn't it be better for survival? What is the evolutionary theory behind it?


texts: Does alpha-amylase from different species have different *optimal* conditions?

texts: Do the optimal conditions for the enzyme isoforms differ between species? Specifically, do the optimal pH and temperature for alpha-amylase differ for that enzyme produced by B. lichiniformis and A. orzyae.


texts: Can immunity to diseases vary by populations?

texts:
A common explanation for the massive population decreases of isolated societies upon contact with Europeans during the Age of Discovery is that the natives lacked immunity to newly introduced diseases.

What does this actually mean?

Is it just a shorthand for "the adult population was not subjected to these pathogenes during childhood and is therefore more susceptible to them" or is there maybe a certain genetic component to it?


texts: What is basis of multifunctionality of "master glands" in the endocrine system?

texts:
I have just started reading about the endocrine system and I am having some difficulty understanding the basis of distribution of glands and associated hormones.

I am using multifuntionality to describe the amount of relatively independent input and output that are shared through a same organ or proximal space. Many of these organs have a heterogenous mixture of endocrine cells sharing the same glandular space.

There appear to be some glands that are considered "master glands" such that they take a variety of relatively independent input, apply some control logic via a diverse set of endocrine cells and tissue and secrete a diverse hormonal output. The pituitary and hypothalamus are the best examples, however the adrenal cortex and the pancreas also fit this definition to a certain extent. Many times the diversity of hormones and cells within an organ have no obvious connection (eg thyroid). Some glands appear more specialized with a relatively straightforward endocrine axis of input and output (eg testes).

Some of this multifunctionality seems unnecessary, in that insulin secretion could occur anywhere and be effective in the manner of an insulin pump, or contain risks due to excessive centralization as in a pituitary tumor or renal artery stenosis, so there must be some advantages I do not understand.

My textbook (Headley, Levine, 6th) seems to minimally cover multiplexing, signal cross-talk and competition between diverse endocrine cells sharing an organ. Its focus on discrete pathways and axes suggests these are evolutionarily unfavorable.

Are there synergistic advantages in shared endocrine infrastructure such as vascularity or metabolic pathways?

Is there some overlying logic that can be used to explain this distribution of glands and hormones regarding multifuntionality-specialization, or is it necessary to view the distribution of vertebrate endocrine system as the outcome of evolutionary contingencies?

Thanks


texts: In this video it is claimed that Darwin's finches arrived at Galápagos Islands just a few hundred years ago. Have there been new speciations over the past 200 years?


texts: What determines the courses of multi-dose vaccines?

texts:
I understand that some proportion of individuals will fail to develop immunity from a single dose of a vaccine.  Rather than test every member of the target population following each vaccination, it is more economical to administer multiple doses to increase the population immunity rate.

But what determines how many doses are indicated for a particular vaccine, and how widely they are spaced?  Are these variables rigorously optimized, or are they just accepted heuristics?

E.g., two doses of MMR are indicated, separated by at least 3 years.  Three doses of HPV are indicated, separated by 2 and then 3 months.  Four doses of IPV are recommended, as are five doses of DTaP!


texts:
The strict dependence of the (human) brain on glucose has always been puzzling to me. While ketones can substitute for a portion of the brain's energy needs, it cannot substitute completely: blood glucose levels below 2--3mM somewhere causes serious neurological problems and can lead to unconsciousness.

Other body tissues are not strictly dependent on glucose, but can oxidize amino acids as well, which is a good backup solution since there is always lots of protein around. But not the brain.

In terms of evolution, this strict glucose dependence must be a major drawback --- falling unconscious just because you don't get enough sugar is probably a bad thing out in the wilderness, when the lions are after you ... So there must be a very important reason.

So why is the brain so dependent on glucose?


texts: Is the Lucy fossil really what scientists claim it is?

texts:
The New Scientist has an article talking about how a baboon bone was found in the Lucy skeleton.

Creationist sites like this, https://christiannews.net/2015/04/23/evolutionary-embarrassment-part-of-famous-ape-man-skeleton-actually-came-from-baboon/, and Dr. David Menton are claiming that the Lucy fossil is another hoax like Nebraska man.

Are we sure that the Lucy fossil is not a hoax? (I am not trolling, I really want to know the truth, and when I search, I get mostly creationist sites).


texts:
According to

Coronavirus has mutated at least once

  The novel coronavirus that has infected thousands of people across the
  world may have mutated at least once — meaning there may be two
  different types of the virus causing illnesses, a new study conducted
  by Chinese scientists suggests.

  Scientists with Peking University’s School of Life Sciences and the
  Institut Pasteur of Shanghai in a preliminary study found that one
  strain — type “L” —  of the virus was more aggressive and accounted
  for about 70 percent of the strains analyzed. The second — type “S” —
  was less aggressive and accounted for about 30 percent of analyzed
  strains.

But also several webpages theorized the virus has mutated before passing from animals to humans.

This page What we know about the Wuhan virus says

  This virus belongs to a family of viruses known as coronaviruses.
  Named for the crown-like spikes on their surfaces, they infect mostly
  bats, pigs and small mammals. But they mutate easily and can jump from
  animals to humans

and

  Where did the new coronavirus come from? The new virus likely came
  originally from bats, scientists say. It isn’t known exactly where or
  how it jumped to humans, though. Viruses from bats often infect
  another mammal first and then mutate to become more transmissible to
  humans.

though

  Coronaviruses can also jump directly to humans, without mutating or
  passing through an intermediate species.

Is something more known about this? Is it possible the virus has mutated twice in a period of time of months?


texts: Why is cannibalism not an evolutionary stable situation?

texts:
In the 'the selfish gene' Dawkins writes (page 109):
"The reason lions do not hunt lions is that it would not be an ESS (evolutionary stable situation) for them to do so. A cannibal strategy would be unstable for the same reason as the hawk strategy in the earlier example."

To quickly summarise this: we consider an interaction between two animals where one possibly stands something to gain. Dawkins then defines 'hawk' behaviour as attacking behaviour, whilst 'dove' is described as peaceful and retreating behaviour. He then argues that a population of purely hawk or purely dove is unstable, since in either of the situations the other kind of behaviour is more favourable. As it turns out, the stable situation is 7:5 for hawk:dove.

Turning to cannibalism, we can regard the hawk behaviour as 'engaging in cannibalism' and dove to be the refraining party. Why, then, don't we see similar behaviour when considering cannibalism, i.e. why don't we see a reasonably large amount of lions engaging in cannibalism whilst the others refrain from it? If I am not mistaken we see in fact the situation more closely described by completely dove?
Any insights are appreciated!


texts: Why is there a carbon atom without a greek letter in protein residues?

texts:
For protein residues I know that $C\alpha$ denotes the first carbon atom attached to a functional group. Each subsequent carbon is given a corresponding greek letter ($\beta, \gamma, \delta$) except for one. For example, each residue in a PDB file has a list of atoms that looks something like this:

ATOM     32  N  AARG
ATOM     33  CA AARG
ATOM     34  C  AARG
ATOM     35  O  AARG
ATOM     36  CB AARG
ATOM     37  CG AARG
ATOM     38  CD AARG

(A,B,G,D are stand-ins for the greek letters). Why is there just a plain C in this list? What is significant about that carbon?


texts: Oxygen balence from growing plants for food

texts:
I had thought photosynthesis and respiration where pretty much Oxygen and Carbon neutral per calorie.

http://news.mit.edu/2014/technical-feasibility-mars-one-1014

  If, as the project plans, crops are cultivated within the settlers’ habitat, Do found that they would produce unsafe levels of oxygen that would exceed fire safety thresholds, requiring continuous introduction of nitrogen to reduce the oxygen level.

Says that a closed system of plants grown to provide calories for human will end up with more oxygen.

Where does the imbalance come from? Where does the extra Carbon go?


texts: Are animals that live in areas where avalanches happen equipped to deal with that?

texts:
Humans take courses to learn how to assess the risk of avalanches and how to deal with it. Additionally, they often use special gear to survive avalanches if they got caught in the middle of one.

What about animals that live in these areas like mountains with snow where avalanches occur (maybe wolves, deer, etc.)? Are they somehow aware of the risk? Do they handle it in any way (e.g. avoid especially steep regions) or able to manage getting out of it?


texts: What drives male fish to spray their milt?

texts:
In mammals the sexdrive of the males is because the intercourse provides a satisfaction where after, the sperm is ejaculated into the female. However, the male sperm doesn't enter the female fish but reproduces by spraying this fluid which contains the sperm, onto roe (fish eggs).
But what kind of (physical) drift is urging them to spray, while they probably don't have an orgasm, or do they?


texts: Is there a reliable estimate of the number of cells on Earth?

texts:
A quick Google search didn't turn up any reliable sources. An awkward Cosmoquest thread gives a rough estimate of 10^25 to 10^32, but this is just a bad extrapolation of the number of cells in a human body. Also, I recently learned that we don't even know the number of cells in humans to good precision.

Has anyone ever made a serious attempt to figure this out? If not, does anyone here want to make a quick calculation?


texts: Parafilm vs Foil for Retaining Plate Moisture while Allowing Gas Exchange

texts: We often plate Streptomyces aureofaciens and grow them in a 30°C room. A post-doc I work with has always loosely wrapped the agar plates in aluminum foil to retain moisture and prevent cracking of the agar media over extended culturing periods (up to 21 days). Another graduate student is saying that parafilm would be much better as it allows gas exchange. The post-doc agrees that parafilm would retain the moisture, but also believes the parafilm will starve the cells of oxygen over time. The parafilm we use has a reported oxygen permeability of 150 cc/m2/24 hours. I don't really know how much oxygen a plate of streptomyces would consume over a day. Thoughts?


texts: What is the difference between infected and infectious in epidemiology?

texts:
I am studying the SIR model and in the infected class I, both infectious and infected individuals are included, as stated here

I know that the model uses the assumption that the disease has an insignificant incubation period so infected individuals are capable of transmitting the disease as soon as they become infected. But what is the specific difference between these two terms? Does infective mean anything different?


texts: About how many covid-19 virus particles is required in the human body before infection and sickness follows?

texts:
Our immune systems are often able to destroy germs and virus particles.
About how many of them does it take to make a 70 year old healthy male sick ? Any ideas ?


texts: Why don't memory cells of the adaptive immune system get activated immediately after being created?

texts:
Why don't memory B and memory T cells of the adaptive immune system get activated immediately after being created?
As this video explains they are created in the heat of the battle. Aren't the conditions for activation there? What mechanism prevents them from being activated right there and then?


texts: What are the optimal conditions for storing frozen glycerol stocks of bacteria?

texts:
The common method of storing bacteria long-term is to collect saturated liquid culture, such as LB, and mix it with sterile glycerol so as to obtain 10-30% final glycerol concentration. The resulting mixture is then frozen, usually at -80 or -20C. Bacteria stored in this way are said to be viable for years. I am curious as to what affects the success of such a storage strategy?

Obviously the temperature should be below freezing, but how exactly is viability affected? Is colder always better (assuming the tube can withstand it)? Is there rapidly diminishing returns after -80C? Is there an optimal temperature? I'm expecting something like a plot of viability after 1 year of storage vs. temperature, ideally with multiple species.
What is the optimal glycerol concentration?
How much does viability drop per freeze-thaw cycle?
Does it matter how quickly you freeze after adding glycerol?
While letting a frozen sample thawed is considered unadvisable, after it does thaw, does it matter how long? Does every second count, or is there little difference so long as it's not several multiples of the lag phase duration?

However, I found it very difficult to locate specific information about the optimal conditions for such storage. For instance, Addgene claims that optimal glycerol concentration is unknown. Moreover, a lot of the older papers on this topic are paywalled (even from my institution). But the experiment to determine it would be so trivial that I can't believe nobody has done it. I am interested primarily in data from actual experiments, and I am interested in glycerol alone as a cryopreservant.


texts: Who was the first to coin the terms of soft and hard selection?

texts:
Soft and hard selection are sometimes used with different definitions. I have been told that at first place hard and soft selection has been defined in the following way:

soft selection: Each deme makes the same contribution to the next generation
hard selection: Different demes make different contribution to the next generation

Who first described these concepts? What was the first paper?


texts: Action of tetracycline on 30s ribosomal subunits

texts: My question concerns the mode of action of 30s ribosomal antibiotc inhibitors — tetracyclines. According to some online resources, the antibiotics enter the A-site, which prevents other tRNA from entering the ribosome. Others say that the antibiotic prevents the ribosome from moving along the mRNA. Which one is correct?


texts: What kind of fruit is this? It is the size of a small avocado or a plum

texts: The flesh inside them seems ripe as it is squishy, and it gives off a strange odor. The smell at first reminded me of menthol. It's about the size of a small avocado, or a plum. A coworker of mine left a few on my desk before he left, but he didn't say what they were.


texts: Is there a way to chemically detect the presence of Fungus in a sample?

texts: I would like to know if there is a way to chemically or somehow detect the presence of Fungus in a sample?


texts: Is the skin of a giant squid/colossal squid similar to the common squid? Does it possess chromatophores to change color? Or did it lose that ability because of the depth at which it resides or due to the comparative lack of predators?


texts: What kind of fish did I see in waters off a tropical island in the Philippines?

texts: Found this while diving in the southern Philippines.


texts:
I have ~100 sets of genes, and each set includes between 2 and 70 genes. I'd like to perform an enrichment analysis on each of these sets to test if they're enriched for OMIM disease labels. However, I'm encountering a problem where the OMIM codes are too "sparse", such that each OMIM code only occurs maximum once in all gene sets. As far as I can tell, this makes the codes unsuitable for enrichment analysis in this case.

I believe that grouping the OMIM codes could solve this, as long as each group-label occurs multiple times in my lists. Grouping OMIM codes seems doable: for example, OMIM codes 601495, 613500, 613502, and 613506 all refer to types of agammaglobulinemia. I could imagine grouping codes based on something like gene ontology labels.

My question: is there a standard way to group OMIM codes?

I see some papers doing something like this, e.g. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4458913/, but I'm new to the field and don't know how "standard" approaches like these are.


texts: Why do I feel my schoolbag to be heavier after meals?

texts:
I am not sure this is related to psychology or not.

My friend casually commented to me that he feels his bag to be heavier after his meal. So I started observing my perception of weight of school bag after every meal. I did this for 3 weeks ( 1 log per day i.e. lunch, 5 days a week, 15 observations).

For 15 observations, 13 times I felt my bag to be heavier. These 13 times I had regular class after lunch. The other 2 times, I had an exam an hour later my lunch.

Is it psychological and / or body function related ?


texts: How do I prepare and clone from E. coli DNA?

texts:
I'm looking for a protocol to get genomic DNA from an E. coli sample so that I can clone a small portion of it using PCR into a plasmid.  (< 500 bp in this case).

It seems OWW (Open Wet Ware) only discusses preparation of fragmented DNA. Does this mean I have to cut it up before I can clone from it?  Any pointers would be really appreciated.


texts: I've been growing bacteria on an agar plate and after putting the dishes in the incubator, this is what I saw. I'm new to bacteria identification, and is this just contamination by fungi or is this actually bacteria colonies? I suppose it is fungi, but what about the white, round white circles on top of the fungi(the top, left picture), is that bacteria colonies?


texts: Are there records of monozygotic twins in which one experiences androgen insensitivity syndrome

texts:
I have given my high school biology students the thought experiment of "What would happen if a researcher induced twinning of a female zygote and then replaced one of the X Chromosomes with a copy of the father's Y chromosome". In theory you should get what would be about as close as possible to male/female identical (monozygotic twins). However, I don't believe it would be possible for this to occur in nature (feel free to correct this if I am wrong). The closest I am familiar with is "Semi-identical twins in which the egg is fertilized by two sperm and then twinning occurs. However this isn't really the same.
However, I realized that Androgen Insensitivity Syndrome, in which a mutation leads to the body not responding to masculinizing hormones, leads to a male developing as female. Is anyone aware of this ever happening? I realize it would need to occur after the zyote/morula split.

Similarly if the SRY gene (essentially the master control switch for masculinizing an embryo) has ever been transferred on to an early embryo of a pair of female monozygotic twins, essentially inducing one twin to develop male.

In essence I'm asking for evidence of physical manifestations of (near)identical monozygotic twins. Has any of this ever been done in research on other species?


texts: What is the significance of cysteine in a protein sequence?

texts: What is the importance of cysteine-cysteine in amino acid sequence? What can I infer if I get a high percentage of C from a protein sequence?


texts:
I have four questions concerning H-W Equilibrium:

(i) In a population of mice, the presence of black spots is the result of a homozygous recessive condition. If the frequency of the allele for this condition is 0.15, what is the approximate percentage of heterozygous genotypes in this mouse population? (Assume that the population is in Hardy-Weinberg equilibrium.)

I thought this implies that $q=.15$, $p=.85$ and thus the percentage of heterozygous genotypes is $2pq = .255$. Online answers seem to yield a ubiquitous $.72$.

(ii) In a population of giraffes, dark brown spots are the result of a homozygous recessive condition. If the frequency of the allele for this condition is 0.10, what percentage of the individuals in the next generation would be expected to be homozygous dominant?

Is this simply $(1-q)^2 = .81$?

(iii)   In a population of monkeys, the allele that causes long hair at the tip of the tail (H) is dominant, while the allele that causes short hair at the tip of the tail (h) is recessive. If 67% of the monkeys have long hair at the tip of their tails, what is the frequency of the dominant allele?

I worked this as $p^2 + 2pq = .67$, so $q^2 = .33$, so $p = 1-\sqrt{q} = .4255$. Again, this seems to come up on the internet as incorrect.

Moreover, in the below picture:

It seems to me that the answer should be $(1-G)^2 = (1-.45)^2$, but this does not appear as an answer.

Any help appreciated.


texts: What's the difference between prions and prion-like proteins?

texts:
If I added a prion domain to a protein, does that make the protein a prion-like protein or would it be considered a prion at that point?

I'm trying to understand what prions are, how they aggregate and what macroscopic shapes they conform to (i.e. a ring vs smaller micelles).

Thank you very much!


texts:
I have a question, maybe a naive one.

Let's assume that we isolated some RNA from a tissue. Do RNA molecules can bind each other if they have the complementary sequence? I know that some small RNA molecules can bind other RNAs and regulate them but I do not know it is possible in this case? It is like 2 different mRNA can bind each other or not?


texts: Does evolution go only in one direction?

texts:
In this video Richard Dawkins talk about intermediate fossils. He describes how the whales were evolved from a common ancestor who lived on land.

But his theory sounds more like a devolution. I thought evolution was coming from the sea to the land and then to the skies. Are there more examples where species evolve back and forth between the ocean and land or skies?


texts:
I have already googled it before but yet unsuccessful in finding the whole topic with intuition. Please help.

A guide to an associated book would be greatly valued.


texts:
I'd like to know if it is possible to identify the spider in the photo below.

In fact, as shown in the next picture, it is very small.

Location: South of Brazil.


texts: How does boiling water revive cut flowers?

texts:
A classic tip to revive wilted cut flowers is to plunge the stem into boiling water for some period of time, and then back into cold water.

What process is occurring that causes the flower to be "revived"?


texts:
Research projects with artificial life generally use creatures that are haploid. The offspring randomly inherit some genes from one parent, and some genes from the other parent.

Q1: Are there any biological species which reproduce similarly? I.e., they're haploid, but the offspring aren't clones. Perhaps hermaphroditic species like slugs or some plants?

Q2: Is there a name for this type of reproduction? If not, I guess I'll call it "pseudosexual" since it's a simplified form of true sexual reproduction.


texts: Has any animal ever had a rotating part?

texts: Outside of microscopic structures (I'm thinking of a flagellum, which I think is a true motor) has any animal evolved a part that continually rotates compared to the rest of its body?


texts: What is this whitish jelly incrustation on a plastic tube?

texts:
I found this plastic tube hanging in the seawater from a pier in the haven of Taranto, Ionian sea, southern Italy. I'm wondering what is the whitish jelly in the lowest part of the photo next to the yellow Botrylloides violaceus. It didn't seem to come off easily (I didn't insist much though) and it didn't have any macroscopic reaction when touched (no contraction or similar).

The photo was taken on the first days of January. The water was shallow in that point (no more than 2m deep) but close to deeper water, as expected from a haven, and rather polluted.


texts: Difference between Trophic and Tactic movements

texts:
What is the difference between Trophic (eg. Chemotrophic) and Tactic (eg. Chemotactic) movements?

In Bryophytes, Anthrezoids are attracted towards Archegonia. This is Chemotactic movement. In Spermatophytes, Pollen tube moves towards Ovule. This is due to Chemotrophic movement.

This is was taught in our school today. But to me, in both cases the male part is attracted to female part using certain chemicles. So what is the difference between them? Broadly speaking, what is the difference between Tactic and Trophic movements?


texts: Is it possible to accelerate active transport in plant vascular system using some electronic method?

texts:
I am from electronics background and got an understanding that electrical current affect plant growth. Based on this phenomenon, I got an idea but before I formulate my hypothesis and start experimentation around it, I am looking for some expert opinion on this.

Can we accelerate mineral transport like water movement from root to leaf by some external influences?


texts: What nutrients do I lose in the water when I boil vegetables?

texts: What nutrients do I lose in the water when I boil vegetables. Has to be some water-soluble and heat labile ones right? Which ones?


texts: Why would there be a spike in coverage within a gene in RNA seq data?

texts: I'm looking at RNA seq data in Geneious for Salmonella typhimurium and I occasionally see a spike in coverage for a sequence of RNA within a gene. Why is there a section of the gene that seems to be transcribed much more often than any other part of it? The name of the gene in question is ftsI which is an essential cell division protein that may link upstream cytoplasmic cell division proteins with downstream periplasmic cell division proteins.


texts: How does DNA damage cause ageing in yeast?

texts:
As I understand it, in yeast ageing there is daughter cell and mother cell. The daughter cell is has newly "fresh" DNA and mother cell dies after some counts of replication.

What happens to the accumulated DNA damage in the yeast mother cell?

One of theory of human ageing is accumulation of damage in nuclear DNA. The daughter yeast cell is clone of mother, and has same DNA. What happens with this damage?

Edit to simplify: Why is the DNA damage not transferred at all to the daughter cell? The repair mechanism in humans is evidently not perfect, because DNA damage is one of major ageing theories. So if we die from this, how do yeast get around the detrimental affects of DNA damage that cause ageing in humans?


texts: Why are archae and bacteria grouped into separate domains?

texts: Archae and bacteria are both Prokaryotes. Why are they group into two separate domain?


texts:
Almost 10 years back when I was a kid, we had a picture in our school text of wild buffaloes drinking water from a river - which was visibly muddy. I asked my mother of why we need to drink filtered water when they needn't. The question still persists now!

Do wild animals have better immunity? Has the potency of the human immune system reduced in the course of evolution due to better hygiene (different from hygiene hypothesis?)? Do animals also suffer from infections (like giardiasis which are known to spread by drinking contaminated water) and hence lesser life expectancy (due to lesser hygiene?)?


texts: E.coli divides in 20 minutes and its DNA replicates in 38 minutes .Kindly explain.


texts: Does gray/white hair turn gray/white from a normal hair? or does a gray/white hair actually grow gray/white originally?

texts: I am really curious if hair actually tuns white/gray from default color, or does it have a defect as it is made and grows out of your head a different color?


texts: What is the chemical composition of an egg shell?

texts: It ought to be some combination of C, O, and H, I presume. But really why should I care if eggshell gets in my eggs while I'm cooking?


texts:
I want to know what ranges of value can D' in linkage disequilibrium take? Because I read in my book (An introduction to population genetics by Nielsen and Slatkin) that D' is guaranteed to be between 0 and 1. Whereas at the link provided below, it says D' can be between -1 and 1.

http://csg.sph.umich.edu/abecasis/class/666.03.pdf

Could someone explain this discrepancy? Because now I am totally confused.


texts:
I tried reading by light from a neighbouring room and felt sleepier than if my own lights were on.

Is there a formula for the intensity of light vs physiological preparation for sleep(calcium, melatonin)? Or is there a threshold intensity below which the body goes to "sleepy mode"?


texts: For a mesophyte growing in a moist soil, water potential of its root sap is -3 atm, then how to find the water potential of moist soil and leaf respectively?


texts: How much oxygen does a human need to breathe?

texts:
So, I know that the title isn't very precise, but so is my current knowledge of the subject. It begs the question of what unit are we talking or maybe percentage? Let me explain the situation.

Earth's atmosphere consists mostly of 21% oxygen and 78% nitrogen. O2 is the compound we use to breathe, but nitrogen on the other hand is just a non-toxic gas and is not necessery. Well, it is as it increases pressure which is essential for human existance, BUT it can be substituted by other non-toxic gas like Argon.

On Earth's highest mountains oxygen percentage is on a similar level, but the pressure is lower. Hikers have to use oxygen tanks. If I deduce well, with lower pressure, human needs more percentage points of oxygen than in higher pressure.

Now I am writing a simulation of space ship, in which there is a security system, which controls oxygen in the cabin when pressure drops and it should always keep oxygen amount correct for any pressure given.

How can I calculate the perfect oxygen amount in air and what would be the actual unit of it? Any idea of a unit I have come with would be $\frac{kg}{m^3}$.


texts: Does alcohol really do more damage to the body of a child compared to an adult?

texts:
Beside the fact that children and teens (people under the age of 18 year) usually have less body weight than the average adult, is there a   biologically fundamental difference between the damage done to their bodies compared to an adult when drinking alcohol?

I often read that their organs are still developing and thus alcohol will do more damage, but has this actually been proven?


texts:
The following problem is from Schaum's Outlines on Genetics, 5th edition, by Elrod and Stansfield.  I'm having some trouble solving it.  It is found under a section entitled "Interactions with Three or More Factors" in the problems at the end of the chapter on Epistasis.

  Problem 4.30 (pg. 112):  If a pure-white onion strain is crossed to a pure-yellow strain, the
  F$_2$ ratio is 12 white : 3 red : 1 yellow.  If another pure-white
  onion is crossed to a pure-red onion, the F$_2$ ratio is 9 red : 3
  yellow : 4 white.  (a)  What percentage of the white F$_2$ from the
  second mating would be homozygous for the yellow allele?  (b)  If the
  white F$_2$ (homozygous for the yellow allele) of part (a) is crossed
  to the pure-white parent of the first mating mentioned at the
  beginning of this problem, determine the F$_1$ and F$_2$ phenotypic
  expectations.

In the first crossing, it looks like the type of interaction is one of dominant epistasis between two loci.  So, we could call the alleles for the first locus W and w and the alleles for the second locus A and a.  Then W-A- and W-aa would have a white phenotype, wwA- would have a red phenotype, and wwaa would have a yellow phenotype.  This would be consistent with the ratios provided in the problem.

In order to explain the 9 red : 3 yellow : 4 white, a third locus can be considered with alleles B and b.  Proceeding as above, where we had the locus for W or w epistatic with respect to the locus for A and a, we could have the same locus for W or w epistatic with respect to the locus for B and b.  This time, wwB- and wwbb would be white, W-B- would be red, and W-bb would be yellow.  This would be consistent with the 9 red : 3 yellow : 4 white ratio.

This is where I get stuck.  If the locus for W and w is epistatic in a dominant way with respect to one locus and in a recessive way with respect to another locus, then all onions would be white.  Therefore, I must have done something wrong.  Am I on the right track?

This isn't really a homework problem, despite the "homework" tag.

Here are the answers provided in the text for the problem:

  Problem 4.30 (pg. 115):  (a) 25% (b) F$_1$: all white; F$_2$ : 52
  white : 9 red : 3 yellow


texts: Impact of Terminator Efficiency in Genetic Constructs

texts: I was looking at the iGEM Bioregistry of Terminator parts which offer varying degrees of termination efficiency. I am wondering why studies into combinatorial synthesis of genetic circuits for metabolic engineering include terminators as a variable component within their designs, such as this paper by Woodruff et al., 2017? This must come at great complexity cost to overall library size, where I would of assumed one would take the most efficient terminator and fix it within the design. How could terminator strength or sequence effect optimisation of a metabolic pathway in an impactful manner such that this extra complexity becomes worthwhile?


texts: Why would a venus fly traps mouth that's still "chewing" die?

texts:
A venus fly trap produces leaves that act like traps for insects. A trapped insect is digested over several days. The trap then opens again to catch another insect.

These traps regularly die off. They turn black. They are replaced with new ones. I'm not sure why that happens. As far as I know this is a swamp plant, which makes it unlikely that the traps die off due to being in contact with water. I read that a trap can only be reused 7 times. So I guess the traps are replaced by the plant in some interval.

As the dead traps start to rot in the pot, I pick them up from time to time and throw them away. Recently, during that process, I found this:

and it made me wonder why this mouth would die off. It looks like it caught something. As the mouth is still closed, I think the digestion process is not finished yet. But why would the plant give up this valuable resource?

Is it because the trap could not close entirely? There are signs of rot on the insect, but I don't know if that happened after or during the digestion process. Would rotten prey be a problem chemically? A human can dissolve quite a few things in its stomach, so I guess this could work similarly.

What are the reasons for the traps to die off in general?


texts: Why is the internal capsule dark in this transverse section of the brain?

texts:
Why is the internal capsule dark in this transverse/horizontal section of the brain?
If it is white matter, then why isn't it white?

P. S. : Formalin was used for fixation.
Why the same color was not for remaining white matter.


texts: How does the stomach differentiate between liquids and solids to initiate churning?

texts: Or maybe it doesn't at all. Can the stomach tell the difference between liquids and solids and change its churning process accordingly despite that it has no nerves? Because liquids don't need to be churned, so I figure there's a chance animals, or at least humans, evolved in such a way that the stomach wouldn't waste the energy trying to do it.


texts: What is the difference between Regulatory Gene and Modifier Gene?

texts: If both controls the expression of another gene by physically or genetically interacting with the target gene, which attributes make "Regulatory gene" different from "Modifier gene" or vice-versa?


texts: How would you estimate the number of ATPs required to transcribe, export and translate a single eukariotic protein?


texts:
I had ethanol precipitated a large amount of DNA (2ml) and had to split the sample in half to spin down because only the microcentrifuge has the correct rotor to spin that fast. I want to get as concentrated of a DNA sample as possible. Is it possible (correct) to combine the resuspended DNA? I wanted a total of 30 ul of extracted DNA. Could I resuspend each of the two sample in 15 ul and then combine them?

What is the best way to go about this. I realize just keeping them separate might be the best option. I also realized I could've lost DNA when transferring the sample to a smaller tube. I did this because I don't believe it is correct to spin for longer at a lower speed...


texts:
I had learnt in a plant biology course that, all the flowers are actually originating from leaves, with several mutations. I wonder what makes a flower sparkly like this.

Photos belong to a Phalaenopsis Orchid (White) (under direct sunlight) . But I believe this can be observed in many plants.

When searched for it, I saw one explanation on that they shine right after they are watered. But I observed this long after the plant was watered. So I guess this is not the case.

Also I've read about the pigments that absorbs different wavelenghts and give the plant its color. But I couldn't find an explanation about this sparkling view.

Another thing I read was about the shiny views of some flowers, like buttercup flower. It is said that this is originating from flat cell shapes. (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5332578/). But again, this is different than what I am asking.

Biology is not my major (probably as you have already guessed :)), so I might not be searching it with the right keywords. So I will be glad to get some help. Thank you :)!

Edit:

Another photo, taken with flash light. The shiny view is only in the side leaves (petals and sepals), not in the middle parts.


texts: Determine secondary structure (per residue pair) from a protein contact map

texts:
Given a protein map contact map (which for this particular case is a matrix of all Ca-Ca atoms in protein 1a3a that are less than 8 Angstroms):

Question: For each contact, is there an established heuristic to determine what kind (alpha, beta, or tertiary) of contact this is?

Observations: The contacts along the diagonal +4 clearly belong to alpha-helices, but I'm struggling to find a way to identify the parallel and anti-parallel beta-sheets and to differentiate these from a long range tertiary contact.


texts: Why does female's age of puberty inform on mating system?

texts:
Reading from Does increased calorie intake cause increase in libido in humans?, @AlexStone says:

  I'm aware that humans have a dual mating strategy - somewhere between pair bond and casual mating. There are a number of physical measures to indicate this - such as sexual dimorphism between male and female, sperm counts and tested size, as well as age of puberty of females.

How does the age of puberty of females can inform us on the mating strategy?
Why does the observed age of puberty of females suggests a "dual mating strategy"?


texts: Why does the chance of having a baby with Down's syndrome increase with the age of the mother?

texts:
Down's syndrome occurs when either the egg or the sperm cell contain on extra chromosome 21. To my understanding, women are born with all the egg cells in place already, so there's no further cell divisions, and thus no further chance of having one cell with an extra chromosome.

Now, the chance of having a baby with Down's syndrome increase with age:

  At maternal age 20 to 24, the probability is one in 1562; at age 35 to 39 the probability is one in 214, and above age 45 the probability is one in 19

Why is this so, when the egg cells are complete at birth?


texts: What keeps mitochondria from multiplying out of control?

texts:
What keeps mitochondria from multiplying out of control and killing the cell?
According to endosymbiotic theory, mitochondria were once free-living bacteria that got ingested but not metabolized by the host cell. What prevents mitochondria from replicating out of control and overpowering the host cell? The question was inspired by this brainstorming session about engineered endosymbiosis.


texts: Identifying the origin of replication of an unannotated *E. coli* plasmid

texts:
I have attempted a few searches for a list of origins of replication for plasmids in E. coli, but I was only able to find a list of origins, but not their individual sequences. The available plasmid maps are often extremely vague on where exactly do the origins start or end, and in any case it would be extremely tedious to collate a list of origins in order to determine the exact origin of replication of a plasmid.

Is there a database of origins of replication available anywhere that would allow one to perform BLAST searches on the plasmid sequence in order to obtain the compatability group of the plasmid, in cases where the plasmid's origin of replication is not specified?


texts: Semantics Question: epigenetic mark on a person's DNA?

texts:
In an article on biomarkers of child abuse, the author referred to an "epigenetic mark on a person's DNA". It's a popular science article, so the language may reflect a combination of the journalist's scientific competency and his or her desire to communicate complex topics efficiently to a lay audience. Is that an example of such language?

My understanding was that anything in the realm of "epigenetics" is happening to something other than DNA. Is it technically correct to refer to an "epigenetic mark on a person's DNA"? Correct enough? Only potentially misleading? I'm trying to wrap my head around the whole epigenetics concept.


texts: Why is there an increase of diagnoses of Lyme disease?

texts:
On the Center for Disease Control page for Lyme disease, you can see the progression of reported cases of Lyme disease from 2001 until 2016 and see that over time, there are more reported cases of Lyme Disease.

I am wondering if there is an actual increase in incidence or if, perhaps, there is an increased awareness of the disease causing doctors to be more likely to test for it (and diagnose it) than they were in 2001.

Is there any information supporting one or the other?


texts: Can systemic venous congestion caused by tumor?

texts:
I am thinking, if 1) little compressed superior caval vena and 2) some vein compression by tumor, can cause systemic venous congestion.

I think this is only in rare occasions.
However, the question is if this is possible.

Can systemic venous congestion caused by these two factors?


texts: Can protein precipitate out in alcohol during DNA extraction?

texts: In common lab sessions to extract DNA from strawberry or cheek cells, will there be protein contaminating the DNA extract in alcohol? If so, how can we prevent protein from precipitating out of the solution?


texts: what is the princlple of using DMS (Dimethylsulphate) for structural analysis of rRNA?

texts:
I want to check the secondary structure of rRNA (PTC) in a particular position by using DMS footprinting. I have deleted the modified nucleotide (m5c) which is present in the PTC and it helps in the ribosomal structural stability. I am interested to know after the deletion of the modified nucleotide.

I am using DMS treated RNA with primer extension. I don't understand the basic principle of DMS reacting on RNA. can you please explain me.

I used this article for reference:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2701642/


texts: Expanding the SETI initiative to seek intelligent data within DNA sequences?

texts:
I've recently read a couple articles dealing with long term data storage, and DNA was suggested as one of the prime candidates for long term storage of digital data additionally, there is this article which deals with decoding of long storage data. These popular articles, though simple do mention important concepts- how packets are stored in DNA use addressing schemes, redundancy of storage, writing for a recipient who may be using a different language, etc.

This made me think - we have the SETI initiative which is looking for signs of (intelligent) life in the universe. That organization was created long time ago, and uses technologies of those days - radio waves. The modern science knows that we can store a lot of data in DNA, and that most organism DNA contains only a small fraction of protein coding sequences and a large amount of non-coding material. If I understand correctly, some of the non coding material is repetitive and highly preserved. Has anyone considered expanding the search for intelligent life to include examination of DNA for messages that might've been left by other intelligent species actually visiting earth?


texts:
What is the energy penalty of maintaining rarely used synapse?

I'm wondering if forgetting is cheaper than remembering unnecessary details.


texts: How are the gene sequences of individual sperm and egg cells "randomized"?

texts: What I mean by "randomized" is, in the place where an egg cell or sperm cell is made, what is the mechanism by which each one is not made identically? Though I am a layman, I'm pretty sure that if the sperm cell that was right next to "me" had made it to the egg instead of the one that did, the resultant human would have a different genomic sequence and different features.


texts: Lions protecting girl in Ethopia -- how plausible is it that they understood situation?

texts:
Several years ago we read of a girl who was apparently threatened by humans being protected by lions who chases off the males and stayed with the girl. Explanations like, "her crying resembled that of a cub" etc. were invoked.

Why is it so hard to believe that adult lions who almost certainly know the difference between a lion cub and a human could not have been acting altruistically as they sometimes apparently do with, for example, prey animals that they sometimes encounter? If a domesticated dog or cat protects a human, we accept that they know what they are doing, do not confuse the human with their own young. Lions are plausibly more intelligent than a dog or cat or at least within the dog/cat range.


texts:
I researched about it by searching on Google and reading some bacteriological articles, but I did not get any answer. I also asked some of my teachers, and they were also a bit confused. Some said that it is possible and others said not. So the question remains:
Can a bacterium infect another bacterium? If so, how?


texts: How to determine the fastest metabolism ?

texts: Which is the fastest metabolism ? Fructose metabolism or Glucose metabolism


texts: Are human eyes equally sensitive to AC, and DC lamps?

texts:
Definitely anecdotal.

This friend is hypermetropic, and uses reading glasses. He doesn't have major issues facing car headlights, or using a torch (the one with a bulb - not a white LED). Yet place him in front of a TV/Computer screen, and he'll develop an ache in the eye sockets in no time.

I understand an electric torch, an incandescent bulb, a car lamp are all DC types, whereas a TV/Computer screen is fast changing AC.

Are human eyes equally sensitive to light from an AC, and a DC lamp?


texts: How many protons are pumped out per pair of electrons from NADH in oxidative phosphorylation?

texts:
I have searched the web and found that 10 protons are suppose to get pumped out during the electron cycle, but i'm a bit confused.

I'm trying to count, for every complex(1/3/4), the number of protons that are reduced in the matrix versus the number of protons added to the intermembrane space. The numbers don't add up.

my calculations:

complex 1: 4 protons reduced, 4 protons added.
complex 3: 2 protons reduced, 4 protons added.
complex 4: 2 protons reduced(not counting the ones that condens to H2O), 2 protons added.


texts: How to synthesize and isolate single stranded cDNA from an RNA template?

texts: I would like to have pure single stranded cDNA of my choice. I am thinking of reverse transcription from RNA (obtained by in vitro transcription), degrading RNA from RNA-DNA hybrid with RNase-H, heating to 65C to remove any oligoribonucleotides still bound to DNA and pass the solution through G50 sephadex column buffered with elution buffer. This is what I have in mind but are there any efficient ways that are tried before? Or do you have any suggestions over this protocol?


texts: Trouble understanding how uncouplers in the thylakoid membrane increase the rates of the Electron transport chain?

texts:
I am a undergrad in a cell physiology class and just did a learning exercise involving testing rates of the electron transport chain via the reduction of DCPIP, analyzed by spectrophotometry. ( I think...  D:   )
So from what I understand, uncouplers stop the "connection" of the ETC and ATP synthase indirectly. And in our lab period we used a hydrogen ionophore(ammonia) as our uncoupler( I think... D:  ).
So for our results I obtained this graph**(The Y axis should be absorbance(600nm)) sorry**...:

Where tube 1 through 3 was a collection of thykloid membranes isolated from spinach leaves; tube 1 being kept in foil until the 10th min mark to then measure absorbance as a control. Where tube 2 and 3 were exposed to light for the 10mins, with absorbance readings being taking every 1 min. And with tube 3 having the added ammonia(from what I understand, the uncoupler).
Therefore how does the ammonia uncoupler speed up the electron transport chain?
My thoughts after googling are that since PQ( plastoquinone) is partially responsible for establishing the proton gradient for the thylakoid mebrane, since it transports H+ ions from the stroma to the lumen upon reduction, that if there was this ammonia uncoupler, that could travel through the membrane due to its lack of charge, it could then bind with the H+ ions forming $\ce{NH4+}$ in the lumen.
So then if the lumen now has less H+ ions then the high(lumen) to low(stroma) H+ gradient would be ruined/weakened.
So this is the part I guess confused with; if there is less of a H+ gradient across the thylakoid membrane, then how does that have any bearing on the reduction of the added DCPIP or the speed at which its reduced?
Since tube 3 went the fastest to clear( ~0 absorbance), this is only when it is reduced yes? This means then that in tube 3, the reduction of DCPIP  happened the fastest.
So then does this mean that DCPIP, the artificial electron acceptor, takes over for PQ somehow? Why does PQ have trouble "doing its job" in the presence of the weakened H+ gradient?
P.S: Sorry for the rambling, but I felt including my train of thought was important for others to see where I  misunderstood.


texts: Getting confused by neutralizer, fixator and stabilizer muscles

texts: I know that neutralizers may also be classified as stabilizers because it is their ability to keep joints balanced that holds motion along a specific path. A fixator muscle is a stabilizer that acts to eliminate the unnecessary movement of an agonist's, or prime mover's, origin. Whereas stabilizer muscles act to stabilize one joint so the desired movement can be performed in another joint. How do I classify the flexors carpi ulnaris, carpi radialis, digitorum superficialis, and the extensors radialis longus and brevis, carpi ulnaris, digitorum, and the flexors digitorum profundus, and digitorum superficialis into any one of the three main groups?


texts: Is it possible to express the cistrons from a polycistronic insertion fragment in a single plasmid?

texts:
I have a insertion fragment that I wish to express from pUC19 in Escherichia coli. The insertion fragment is a sub-section from a larger operon sequence and contains just the last two cistrons from this operon.

I plan to insert this fragment into pUC19 under the control of its single lac promoter. Therefore, there will be two cistrons under the control of a single promoter (which is of course, very similar to how it would be expressed in the WT operon).

In my mind, expressing both the cistrons under the control of the single pUC19 lac promoter should allow both genes to be translated; once the mRNA is transcribed, both cistrons have their respective Ribosome Binding Sites upstream of their ORFs, and should be translated.

My question is, has anyone ever had experience expressing poly-cistronic fragments from plasmids using just a single promoter for the entire fragment? I cannot see any glaring issues with this in theory, but I thought i'd ask before I went ahead. Ultimately, I'd rather express both cistrons from a single plasmid, rather than express each cistron on a separate plasmid.

Cheers!
Izaak


texts: Why don't stem cell therapies use viruses?

texts:
Why don't stem cell therapies use a virus to deliver gene editing sequences to stem cells instead of the harvesting-transformation-transplant route.

I thought it might be because of a lack of specificity on the part of the viruses, but then I saw phage display techniques that would seem to make that a non-issue.

I thought it might be trans-cytosis or getting the phages out of the blood-stream and into contact with the stem cells. I haven't found an easy solution to this hurdle, but it doesn't seem to be insurmountable.

I think the main issue is regulatory? Perhaps a lack of precedents in this area. What do you think of my analysis? Is this idea even feasible?


texts:
Why do plant leaves turn yellow if they don't get enough water or get too much water? I want to know the process.

I've been searching in Google for an explanation, but none of the sites did.
Please describe the process.


texts: interpreting enhancer and promoter regions of a target gene

texts:
I am reading a paper which talks about promoter/enhancer regions of certain protein coding genes. These genes are for which evidence points to having strong MEF2 transcription factor binding sites.

The paper says

  Sequence data were taken mainly from the international nucleotide
  sequence database. Accession numbers and approximate locations of the
  MEF2 site centers are as follows: human adolase A, X06351 and
  1985/1986, rat adolase A, X04260 and 450/451...

Now, I looked up accession number X06351 but I find no evidence of a enhancer region on that page.

Can someone explain to me how I should be looking for these sites?

The paper is available for free and can be found here: Link to paper
My interest is in the first and third paragraphs of Materials and Methods where the first paragraphs gives a general description of the MEF2 sites and the third paragraphs gives specific accession numbers.


texts: What are the chances that Tyrannosaurus Rex could roar?

texts:
Tyrannosaurus Rex is now thought to have possibly had lips. Less of chance of it roar though I was told by a friend just because there are birds doesn’t mean they can’t.

Evolution isn't linear, just because one branch of a tree could/couldn't do something, doesn't mean 70+ million years later descendants could/couldn't do it too?


texts: What is the basis for the determining sex from position of adult pelvis?

texts:
I've read that a person with enough knowledge of anatomy can tell the difference between a "woman" who is a slim man that is very good with makeup and an actual woman.

They usually claim to be able to tell the difference between the two by certain things like digit ratios and pelvic position. Is there any basis to these claims? The one I'm specifically interested in is the "position of the pelvis", as that is the most recent example of the claim I've seen. This is a direct quote from a  novel that I'm reading.

EDIT: it looks like I phrased the question badly. As anongoodnurse stated, I'd like to know if there's any basis for telling if a living person is a man or a woman by looking at them.

An example is if you dress up a slim man with a feminine looking face, get a make up artist to make the face look like a very attractive woman, and put that man in a little black dress, would a person knowledgeable about human anatomy, for example a GP MD, OBGYN, mortician, or Sherlock Holmes (kidding), is there any basis for that person to be able to say: "nope, that's a dude".


texts: What does actually occur- ATP is hydrolysed and esterification between glucose and HPO4^2- (formed as a result of hydrolysis) take place to form Glucose-6-phosphate or nucleophilic attack of O- of glucose on ATP leads to formation of ADP and Glucose-6-phosphate?


texts: Are there predefined implantation sites in mammalian uterus?

texts: I do surgical embryo transfer of genetically modified (microinjected) mouse embryos (at 1 or 2 cell stage). As most of the constructs are new, we expect that it may affect birth rate. In case there are no or very low number of pups born we try to investigate at what stage the problem occurs. I dissect the embryo recipients on day 21(+48 hrs to make sure that we don't sacrifice a mouse that is late to litter down). Sometimes I find dark, gelly, regularly interspaced structures on the mesenterial side of the uterus. Initially, I thought them to be implantation sites of the embryos that have been subsequently resorbed for some reason. Until I found similar structures in mice that haven't been mated with male. My question is: are there anatomically predefined sites in an uterus that embryos can invade? Are my dissections just a waste of time and yield no valuable data?


texts: Is ATP produced in a different manner during glycolysis from that generated by the Krebs Tricarboxylic Acid Cycle?

texts:
The ATP in glycolysis is produced in the cell cytoplasm but that from the Krebs Cycle is produced in the mitochondria. The mitochondrial membrane contains an ATP-synthase protein complex that harnesses a proton flow into the production of ATP from ADP and Pi.

Is the ATP made in the cytoplasm during glycolysis made in a similar or different way?

https://www.youtube.com/watch?v=mfgCcFXUZRk


texts: How to estimate MOI for a complex cell type

texts:
I am currently confused about the estimation of multiplicity of infection (MOI), here is an example in a scientific article

in figure 3b, they tested the virus, and get estimated MOI based on this:

  To estimate the MOI, we isolated a total of 45 individual neurons from three animals injected with MAPseq virus into the right LC and sequenced the barcodes within each neuron. On average, infected LC neurons contained 1.2 ± 0.1 barcodes each, implying MOI of 0.43 (Figure 3B).

I am confused which equation they used for estimating?

Thanks in advance!


texts: T cell sensitivity and persistence to specific bacterial proteins

texts:
Currently, the standard tests for Lyme Disease measure antibody production after exposure to a bacteria, Borrelia burgdorferi. Often, the tests are performed too soon after infection, before antibodies can be produced.  Also, infected patients experiencing immune suppression may not have detectable levels of the antibodies to the antigen. In both cases, test results are often false negative.

A new test for Lyme Disease has been developed, ISPOT Lyme by Pharma Labs, which focuses on T-cell activity instead of antibody production. Modeled after the ELISPOT test for TB, it measures interferon gamma (IFN-γ) secreted by T cells in response to stimulation by the B. burgdorferi antigen proteins -- DbpA, OspC, p100, and VlsE-1. After isolating and culturing lymphocytes from a patient's blood sample, they expose the cultured lymphocytes to the B. burgdorferi antigens. If the lymphocytes 'recognize' the antigen, due to previous exposure, they secrete IFN-y which reacts with a blue-colored dye visible in the culture.

Question: Can T-Cell exhaustion affect the usefulness of a serological assay which measures T-cell sensitivity to specific antigens?


texts: What is the rate of bacterial cell death due to viruses on land?

texts:
"The rate of viral infection in the oceans stands at 1 × 10^23 infections per second, and these infections remove 20–40% of all bacterial cells each day." - https://www.nature.com/articles/nrmicro2644

What are the equivalent figures on land?


texts: Is there any API where I can input chromosome location and it will provide us gene names, for example input chr: 1 location 154714693:154754070 and it will return a list of gene names or ID within this region?


texts: What is the nesting period of the European Turtle Dove in middle to southern Italy?

texts:
While the breeding period to the north, in Switzerland, seems to be early May until early July, and I have not found any information for the Naples area.

Also, are they likely to nest a second time?


texts: How can heart disease cause excessive sweating?

texts:
According to google:

  What can cause sudden sweating?

  Excessive Sweating. A person with
  excessive sweating has a condition called hyperhidrosis. ... In
  adults, the most common cause of hyperhidrosis is emotional stress.
  However, excessive sweating is also caused by heart disease, lung
  disease, diabetes, and shock.

Sweating is seemingly unrelated to the heart conditions. By what mechanism can a heart disease cause excessive sweating?


texts: If a fully functional lab grown pancreas can exist, can it be used as a cure for type 2 diabetes?

texts:
Is it approximately equivalent to say that if a fully functional lab grown pancreas exists, then a way to cure Type 2 diabetes could soon exist?

Recently I've already checked out that only the remission exists with some gastric surgery.

reference: 1)http://care.diabetesjournals.org/content/34/Supplement_2/S361

2) http://www.medscape.com/viewarticle/733691(full access require membership)


texts: How do I clean phenol contaminated RNA without losing any of the sample?

texts:
I recently extracted RNA from developing plant leaves for the first time, as part of a very long and intensive experiment. The samples were extremely precious because of the amount of effort that went into obtaining them (harvesting thousands of miniscule leaves, one from each plant, to get the required mass).

I extracted the RNA with TRIzol and chloroform. Nanodrop showed excellent yield as you would expect for actively growing young tissue, but some of the samples had really low 260/230 ratios. I know this suggests phenol or salt contamination, but what can I do to clean the samples without losing any of the precious RNA? And how can I avoid the contamination in the future?


texts: Can the innate immune system defeat a pathogen by itself? Fast enough that we don't develop antibodies, etc.?

texts:
Would we have any way of knowing if our innate immune system destroyed a pathogen without involving the adaptive?

Could a symptomless person who tests positive for COVID-19 with the RNA test, e.g., later test 'negative' for exposure on the antibody test?


texts: What is a good review article source for Physiology?

texts:
I am looking review articles for Physiology.
For instance, Physiological explanation of steps of measurement of the metabolism by Douglas-Haldane.

There is no section for Physiology or metabolism in Advanced Search of Nature Review.

What is a good review article source of Physiology?


texts: How do the B-cells, which are a part of our body, develop antibodies against antigens of the outside world (outside of our body), which they don't even know about? Is it just a random match?


texts: Is it possible to induce erysipelas to treat cancer, under the condition that the patient is to be given antibiotics to control the erysipelas?

texts:
Dr.William Coley was one of the first to attempt fever therapy on cancer patients. He did this experiment: artificial erysipelas to treat cancer.
Coley injected Streptococcus pyogenes directly into the tumor.

My question is: if we repeat a similar experiment today, (under the condition that the patient is to be given antibiotics to control the erysipelas to avoid the ethical debacle), is it possible to develop this as a cancer immunotherapy treatment?


texts: What is the effect of non-vaccinated people on vaccinated people?

texts:
Many times have I heard that anti-vaccine people are dangerous even to the vaccinated population. Is that true? If so, how can it be? People say that germs will attack them, and soon they would eventually grow and spread even toward general population which actually got its vaccines.

I mean it's so counter-intuitive: if I'm vaccinated even when disease will spread I shouldn't be in danger.


texts:
I don't understand this question, hoping someone can help!

One of the following bases does not belong among pyrimidine bases:
 - Uracil
 -  Adenine
 - Cytosine
 - Thymine

I thought that everyone was bases, expect that uracil is in RNA, and that in DNA it is replaced by guanine.

Also one more question:
Which of the processes would never contribute to genetic variation within a bacterial population?
 - Transformation
 - Meiosis
 - Mutation
- Transduction

I have a hunch that the right answer is mutation, but I don't know why. If you know the answer, it would be very helpfull if you could explain why :-)


texts: I have been looking for hours trying to find this number, and can't seem to get a straight answer.  I've seen some studies that calculate the change in BMI, but for some reason they don't give you the actual numbers, just the rate of change.  I've also found information for individual countries, but I want the global average, and would prefer not to do a calculation with 196 different sets of data.


texts: Why does inbreeding cause genetic defects, but cell division in one's own body does not?

texts:
I was watching a DNA transcription video when I realized that cells basically create copies of DNA all the time in our body. There may be a few mutations/errors, but it works out fine. However, when the haploid DNA in sperm combines with the one in the egg, there's so much extra work to be done to avoid errors. It's like if I write some software in one project and try to combine it the code I've written in another project, it's easier for me to do it because my coding style is similar and I know the code. But if I have to merge somebody else's code into my code, there would be a heck of a lot of merge conflicts and errors. Sure, I may learn better programming from the other person's efficient code, but the amount of bugs, testing etc. will be much more cumbersome.

Some research says:

  Malformations or harmful traits can stay within a population due to a
  high homozygosity rate, and this will cause a population to become
  fixed for certain traits, like having too many bones in an area, like
  the vertebral column of wolves on Isle Royale or having cranial
  abnormalities, such as in Northern elephant seals, where their cranial
  bone length in the lower mandibular tooth row has changed. Having a
  high homozygosity rate is problematic for a population because it will
  unmask recessive deleterious alleles generated by mutations, reduce
  heterozygote advantage, and it is detrimental to the survival of
  small, endangered animal populations. When deleterious recessive
  alleles are unmasked due to the increased homozygosity generated by
  inbreeding, this can cause inbreeding depression.

But bed bugs for instance, have managed with inbreeding without any problem (goddamned creatures!).

The question I'm asking is from the perspective of how the DNA combination and copying happens. Since the regions chosen during meiosis is random, shouldn't a similar DNA from sperm and egg resulted in a more stable genetic code since they are similar? I'm not looking for simplistic answers like "because Nature wanted diversity" or "because recessive alleles are unmasked".

I'm looking for a more fundamental explanation about the property of DNA, or the process of copying/merging these complex structures. Why does merging two similar things cause more problems than merging two dissimilar things?