CharonY

Scientific American is pretty good, I loved to read it when I was your age.

I think the question is aimed at something different. In most tox studies significant aggregation of NP is happening resulting in various forms of cell entry (including endocytosis). However, most metal NP appear to create oxidative stress (with a few studies suggesting alternative, but mostly uncharacterized pathways). Metal ions do permeate membrane (via porins and certain ion channels, mostly), however the concentration of free metals tend to be relatively low in solution. I am not aware (but certainly am not an authority in this area) of any differences in this regard between gold and other metals. I am a bit wary with regards to tox data on NP as at least the initial ones did not control well for further aggregation (as mentioned), in one case rats were killed with carbon nanotubes, but not due to toxicity, but because they were literally suffocated. The various groups are improving their assays, but I have not yet seen anything terribly conclusive in terms of mechanisms. So far the convention wisdom tends to be that it is a matter of available surface rather than any new mechanism (nano compared to bulk, that is). There are exceptions that suggest otherwise, but good data is hard to find and good explanation even harder.

I think the thought that they are junk has been abandoned around ten years ago. I think the main differences is that more and more functions are being elucidated on a larger scale.

In that case you just need to introduce gfp into the cell and either maintain it on a plasmid or let it recombinate into the genome.

Depends on what you mean by tagging. The most common form is to make them produce it.

This has been mentioned numerous times on the boards. Molecular biology has opened up new perspectives in the study of evolution and people are trying to set up a new frame work that actually accommodate the new findings. However, considering the complex nature it is far from trivial to do so. The modern synthesis has remained popular as it is (relatively) concise. Now we find bits and pieces that cannot be easily integrated into an universal frame work that is useful for every application. Oftentimes we are on the empirical level of things and have not yet managed to derive a higher abstraction from it.

I am not sure why this is supposed to be relevant. But simply put, sexual reproduction is more time intensive compared to asexual reproduction. Often specialized cells (gametes) have to be produced, then recombination with other cells are necessary etc. etc. Even in simple cells like yeast meiosis takes hours. During that time other organisms are already done reproducing for a couple of generations. Again, the question is more, why bother with it?

In many animals (best studied in birds) imprinting is quite important in the definition of sexual preferences. As such it reasonable to assume that certain genetic factors together with environmental factor will determine the outcome within a continuum. A hard-wired genetic basis is, considering the complex traits upon which humans determine suitable mates, is not very realistic.

Assuming everything else was ok and you really have sufficient enzyme (i.e. normalized activity against concentration, for example), then is possible that e.g. pH shifts due to the ammonium sulphate (or other treatment) may have denatured part of the proteins. Sometimes high salts also lead to irreversible activity losses, but especially with ammonium sulphate it is rather rare.

In a study published in PloS one researchers have handed out questionaires to assess the moral orientation of the participants. After filling out the survey, candidates were asked to defend their position. The trick was that while turning over the sheets the wording in the question changed to the opposite of the original statement. Interestingly over 50% of the participants even argued for the opposite of their original attitude. PloS One Of course, this calls into question the validity of such surveys, but also shows the flexibility of attitudes to some extent.

I have not scrutinized it properly but I feel it is a bit similar to the Lancet article in the late 90s, I think. Except that one ended prematurely. This one seems to abandon typical tox-study design to something more exotic. In these cases there is always the suspicion of data arrangements to find and over-emphasize weak effects.

As Ophiolite mentioned, the majority of species reproduce asexually. Bacteria have sex, but do not reproduce in that manner. On top of that there are species who can reproduce sexually as well as asexually (usually by having different life cycles). That being said the evolution of sexual reproduction is still an unsolved problems. Most models have trouble find that sexual reproduction actually has a benefit over asexual reproduction. The reason is that it is associated with a two-fold cost. All things being equal, an asexually reproducing population will grow at twice the rate as a sexually reproducing one (i.e. the sexually reproducing population will only inherit half of its genes to its progeny). Most assumptions of fitness increase due to increase in genetic variation due to sex do not overcome this barrier (this is presumably why bacteria utilize sex, but not for reproductive purposes). That being said, some newer works offer potential solutions to this problem, but it is far from trivial or being solved conclusively.

Precisely. Your job is essentially to listen and learn and ask questions if something is not clear to you. Communicate clearly and you should be fine. We generally do not have any expectations in terms experience from undergrads. And even if we had, it would be fairly unreasonable, as each lab has its own workflow. What they are going to do is to familiarize you with the inner workings of the lab and show you your responsibilities. What you should bring with you is very simple calculation abilities (for basic stuff like calculating molarities, for example) and if you are uncomfortable with it, let them double-check. In fact, at the beginning try to verify everything just to make sure that you got it (usually they will do some control, but if they are busy or overworked, they may neglect that). It is always better to ask than to ruin someone's experiments, as ecoli mentioned.

There is also the fact that studying/postdocing lasts for a few years, usually. People might get used to and subsequently get attached to their current environment. A kind of increased viscosity born from proximate familiarity, if you will. Out of convenience people may seek to avoid another change (i.e. back to their country of origin). This may even be the case if the work environment is not objectively better and I suspect that something similar is the reason why many people stay in an academic environment (despite worse job opportunities, for example).

How is a dilution from 10 ul to 5 ml a dilution of 10^-3 ? To the question, what is the total dilution of the solution that you put on the plate (note that you only use 5 ul).

Basically it is assumed that the saliva of the mosquitos triggers a weak allergic reaction. However, it should be noted that there are apparently histamine-dependend as well as histamine-independent pathways resulting in the itch. The latter mechanisms is not quite clear, but seems to play a major role.

Yes, it is just an attempt to integrate existing knowledge into a more comprehensive theoretical framework and potentially discarding or limiting prior assumptions that are not found to be universal (e.g. species concepts and similar issues).

For the actual adhesion you just need a suitable surface (such as polystyrene, though in some cases you need an existing cell layer, for example). The cells will first settle on the surface, but to actually adhere and grow you need to keep the cells happy by providing a suitable environment (including temperature, pH, and gas atmosphere), as well as nutrients. Practically you have a medium in a suitable dish and seed it with fresh cells. The cells will settle, adhere, and form a layer within that dish (if you keep them happy).

Actually fermentation does not primarily yield energy but more generally serves as a means to regenerate NAD+. Also I found it easier (and in many ways more accurate) not to see the electron accpetor of anaerobic respiration as the agent to oxidize a given substrate (an electron donor, such as glucose), as in truth many different metabolic activities yield reducing equivalents in parallel which are then used into the the same electron transport chains (with a given acceptor in the end). In terms of electron balancing it does not make much of a difference. In terms of understanding metabolite flow and the underlying reactions it does.

There are markers being associated with homosexuality. As usual with association studies not many are confirmed and linkage can be weak (e.g. Rice et al 1999, Science)

Actually, I think this is a prime example of a nomenclature being arbitrary. For instance, Glycolysis could be seen as an energy pathways under this viewpoint (it generates ATP) but also as a simple catabolic pathways funneling carbon into the TCA cycle for other, anabolic processes. The TCA cycle is not directly involved in ATP production, yet it produces reduction equivalents, which are crucial for oxidative phosphorylation . I am aware that this complicates matter, sometimes unnecessarily so. But it also highlights why biology is complicated: things are interconnected. A biochemical view tends to cut-off at a certain point in order to understand a certain sub-process (and I presume, to retain sanity). In order to understand physiological consequences of these elements their interactions and resulting emergent properties have to be understood (though we have preciously few tools and methodologies to achieve that).

Also, as an add-on note, this still could happen today (though hopefully at smaller scales), as obviously drugs can only be tested in a limited number of ways. Trials normally do not involve pregnant women, for instance (and for good reasons). And rats or other test animals do not necessarily have the same susceptibilities as humans. This is why nowadays most drugs have extra warnings in case of pregnancies. There is no 100% certainty when it comes to tinkering with biology.

The volume determines how far they can be transported through your mouth and oesophagus to your stomach, if we talk about splashes. Think about a small ingested droplet coming in contact with your mouth area, it will mostly spread out and not travel far (i.e. the viral particles will be spread nicely in your mouth area, a few may be transported to your oesophagus, but on the way there there are a lot of nice cells they can adhere to). Think of it in terms of sample loss of a sample moving through a tube or something similar with an adherent surface. Of course, if you got a huge splash and your mouth was open (thus ingesting a significant volume), then yes, that could be an additional issue (but really what have you done to do that?). But think about it the following way, if a significant amount ends up in your stomach, quite a bit will already infect your mucosal surface. I would kind of worry about that first. So even if the portion ending up in your stomach deactivates all of them, you still have a large amount of viral particles in your mucosal surfaces. Especially if the droplets are small (and hence large surface to interact). Though due to their inability to replicate (I hope) the overall health effect should still be minimal. A couple of infected cells are usually not sufficient for successful establishment of a tumor (increases lifetime risk, though). Most lentiviruses are not terribly pH stable, but it can take a little while for them to be totally deactivated (30 mins to 1h). The thing is that they are generally tested for their ability to reproduce, which in your case they should not be able to, anyway.

There are dozens of details. Mostly (as I mentioned) quantitative in nature. Certain proteins are, on average, higher expressed. Other lower. Cytoskeleton is different. They become motile again, etc. Unfortunately there is only a graduate difference, which can also be found in, say, different cell types within our body.

A decent GC/MS is quite expensive. With everything included you are looking at around 20k and up. For a standard LC-MS/MS in pharmaceutical validation we are talking more towards 50k and up (though used ones may be around for around 30k, maybe). While in my opinion I do not think that it is too hard to master (though I may be biased), I doubt that one would hire someone as a technician without at least a bachelor in a related area. Labwork and IT are for the most part extremely different skill sets. The majority of the time will be involved in creating sample prep protocols, analytical methods and validating them. The interpretation is for known compounds is fairly easy, if you are not looking into very complex matrices. There are commercial database for spectra searches (cost an arm and leg), though often just reference material is used (which is usually better, anyway, if you follow non-standard protocols). I would really figure out whether you can get training on the job, rather than trying to get one on your own. LC/MS is in principle similar, but it depends on the compounds you want to look at. I.e. can you use LC for separation or is GC more suitable (e.g. how volatile are the components to be identified). If you want to start a business (i.e. offer services for sample analysis) then you are in a world of pain of getting your system certified.