Can a brain be transplanted?

"Is it possible" has a carefully conditional "yes". Do we have the expertise or technology to do it now? No. One of the biggest difficulties is that nerve tissues (the connections between brain and rest of body) will take time to heal... time during which the brain cannot sufficiently give commands to the rest of the body to keep autonomic functions running.

Head transplants, however, have been "successfully" completed using monkeys. The monkey lived for sometime after the transplant, but eventually died. China has also been known to do a similar procedure with dogs.

Caution, this may be too explicit for some; I'm not sure ethics boards would allow it nowadays:
Monkey Head Transplant

Alternatives to TBE buffer for denaturing polyacrylamide gel electrophoresis of DNA and RNA?

I just stumbled upon an article promoting 10 mM sodium borate as an alternative to the well-known TAE and TBE buffers for agarose gel electrophoresis of DNA (Brody & Kern, 2004). They claim that sodium borate outperforms TBE and TAE at high-voltage conditions due to the significantly lower heat development.

I'm currently using TBE buffer and gels with 7M urea for my denaturing PAA gels, and I'm wondering if there are similar alternative conditions for those denaturing PAA gels of nucleic acids?

I couldn't find anything on using sodium borate for denaturing PAA gels, so I'm wondering if it should work the same as for the agarose gels or if it just isn't a good buffer for that kind of gel.

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Brody, J. R. & Kern, S. E. Sodium boric acid: a Tris-free, cooler conductive medium for DNA electrophoresis. BioTechniques 36, 214–216 (2004).

What is the relationship between sexual and and natural selection?

To Darwin's point of view, sexual and natural selection are two different mechanisms. Then, we tended to consider that sexual selection is part of natural selection. The part of natural selection that is not attributed to sexual selection is sometimes called ecological selection. Today, our understanding of these mechanisms brought us to consider the meaning of these words slightly differently.

Natural selection is not anymore the result of a struggle for survival. It is any process yielding to a change in allele frequency through a long-enough term difference in fitness. Fitness is a index of how much an individual, a gene or whatever, leave copies of itself after a long and short enough amount of time (one might not agree with this definition I guess). Take two strains of bacteria in two petri dish, consider they are one population and let the bacteria grow. One strain will grow faster and the allele frequency will vary over time. It is the result of natural selection although there were no competition, no struggle at all given that they were not in contact.

Sexual selection is a type of natural selection that involves sexual competition. There are two types of sexual competition, the so-called inter- and intra-sexual competition. Inter-sexual competition means that one sex chose the other one, while for intra-sexual there is no choice from the other sex. For example, if you see two animals fighting, they either fight to have the physical acces to the other sex (intra-) or they fight and then, let the female decide which one is the best to mate with (inter-). These two concept of intra- and inter-sexual competition might somehow overlap in some specific case. I would argue that the concept of sexual competition and therefore of sexual selection have never been accurately defined. Therefore, I would not complain if one prefers to give up the concept of sexual selection to use only the concept of natural selection.

Many articles state that sexual and natural selection act on a trait with the same or opposite directions. Given the above argumentations, you could as well say that there are two different forces of natural selection. if the trait is at state 'A', then the individual is very attractive to the other sex but is likely to not be able to escape a predator. This is the case of most of the trait we think of when talking about trait evolving through sexual selection. See Zahavi's handicap principle for more information.

physiology - Would my hands sweat this much if I wasn't wearing gloves?

Hand sweating has been fairly well-studied, both because sweating from the hands is one of the main mechanisms of heat dissipation at higher temperatures and because there is a significant effect on palmar sweating by the autonomic nervous system (the main cause of hyperhydrosis of the palms).

Disregarding autonomic effects (stress response), the single most important determinant of hand and foot blood flow is the thermal status of the body core. Heat dissipation is more marked in the hands than feet, and remains so as temperature increases.

Studies have been done of palmar sweating in extremes of temperatures, palmar sweating changes with aging (decreases), palmar sweating in disease, etc. But what has not been studied is the effect of localized heat on sweating of the palms, which would be of interest to you if sweating was a result of the insulating capacity of the gloves.

What is known about palmar sweating is that it is an ongoing and important process in both genders, at all temperatures, and at all ages. The most reasonable assumption then, given the limits of the literature, is that your hands sweat continuously and steadily at a given temperature, and it is highly likely that you are noticing it when wearing gloves only because the vapor barrier caused by the gloves prohibits evaporation.

_{The roles of hands and feet in temperature regulation in hot and cold environments
OBSERVATIONS ON THE ACTIVITY OF SWEAT GLANDS WITH SPECIAL REFERENCE TO THE INFLUENCE OF AGEING
Why do I get sweaty palms?}

biochemistry - Do humans have chemosensors for nutrients or chemicals?

I'm reading about chemoreceptors on Wikipedia, and see that the typical ones are mentioned: taste, smell, CO₂. I would like to learn more about the other kinds of chemoreceptors that humans may possess. I'm particularly interested if these can detect chemical compounds, or lack of thereof in food.

Here's an example:
Do omnivore mammals vary food preferences based on dietary needs?

There's "rapid recognition of Indispensible Amino Acid(IAA) depletion in the rat brain's IAA chemosensor, the anterior piriform cortex (APC)"

Reading the article above, it appears that at least rats and birds can develop aversion to food that does not contain indispensable amino acids. This is done through chemosensors in the brain. Do humans possess any similar chemosensors?

Thank you for your input!

lab techniques - What are good practices with reusing desalting columns

Regardless of what protocol you use, and what the advertised efficacy of that protocol might be, in any situation like this I think the important thing to consider is: what would happen if the material taken from a re-used column was contaminated by a previous application? Can you live with the consequences of such contamination?

If you are preparing DNA for further use (PCR and/or cloning and/or transformation) then you run the risk of propagating a contaminant through subsequent steps and getting into a real mess. I worked in a lab once where one postgrad ended up spending several weeks working with a cloned fragment that was actually derived from someone else's work in the same lab (although not due to re-use of a column as far as I remember).

If you are preparing protein samples then the risks are possibly reduced, but if the protein sample is going to be subjected to sensitive methods (blotting, MS) then again, could get messy.

genetics - How to compare SNP from genotyping results for multiple people with a known phenotype?

Each rsid identifies a unique SNP in the genome. Thus there should not be any entry in the files that have the same rsid but different chromosomes and/or positions. If you do find this, it is likely that you have data from different versions of the assembled genomes.

To find genetic variants associated, i.e. correlated, with your trait, you need to focus on the genotype at each of the SNPs. For example, SNP rs3094315 is an A/G polymorphism, i.e. an individual can either have the genotype AA, AG, or GG. To find if it is associated with tongue rolling, you would count the number of AA, AG, and GG individuals (alternatively you could sum the number of A and G alleles) in the group that can roll their tongue and compare those numbers to the group that cannot. You would then repeat this for each SNP that you want to test. For most SNPs, there will be no difference in proportion.

That being said, this is not a modest undertaking as this a cornerstone of human and statistical genetics. There are many issues that could strongly bias your results (e.g. population stratification, genotyping error, linkage disequilibrium, multiple testing). To learn more, you can read about the Cochrane-Armitage Trend Test and the PLINK software. If you are really serious I recommend Applied Statistical Genetics with R by Andrea S. Foulkes.