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CharonY

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Everything posted by CharonY

  1. Well, I would not know why they would be called remnants.Also, they are generally considered to be mobile genetic elements (or selfish agents, if you want) that may have arisen very early in history.
  2. Essentially the saliva itself (or most biological matrices for that matter) contain nucleases that can rapidly degrade free DNA. Add microorganisms to the mix and you look at a highly unstable system. However, for some SNP analyses even the degraded DNA may be sufficient (as only very small fragments are required). Unless, however the information of likely candidates or very close relatives is stored somwehere, the identity may be very hard to assess.
  3. Note that I said that teen pregnancies carry increased risk for infant death and did not give any indication of possible causes. This may not be that obvious as bodily changes are still happening between age 12-16, where the largest increase in infant mortality was observed.
  4. Teen pregnancy increase the risk of infant death by something like three, IIRC. So together with Timo's calculation it is clear that it cannot be a major reason for the differences in infant mortality (though it certainly contributes to some extent).
  5. AFAIK it is not possible to filter for a single hit per species. What you can do is to limit your search to a certain groups of species, depending on what you want to see. Alternatively, save the complete output as table and filter it.
  6. Actually the mass does not really play a role in the calculation of electrophoretic mobility (think Smoluchowski). There appears to be a MW-dependence on charge density, that may allow for the differences at lower MW, though. M/Z really only is relevant when e.g. looking at movement of charged particles in vacuum.
  7. 1) Are you mixing up gel electrophoresis and Southern hybridization? 2) Free electrophoretic migration is dependent on electrophoretic mobility. For DNA it becomes size independent above a certain length (bit above 20, I think). The major difference, however is the use of a gel. The sieving effect has a dependence on the linear size. Due to this dependence, you can relate the migration back to the DNA length.
  8. Simply put, the genome of an organism is the total of its genetic information. Thus, the genome sequence of humans consists of the sequences of the 46 chromosomes. Heterogeneity can refer to a lot of things, including distribution of genes but also as mentioned the GC content. The latter is often indicative of horizontal gene transfer, or mutations and rearrangements of some sorts. Conserved genomic areas which share a long evolutionary history (i.e. derived from the same ancestor) tend to have similar GC contents.
  9. There is a chance that it re-ligates. In fact, more will be re-ligated vectors rather than vectors with insert. This is what the selection step is for (e.g. blue-white). Religation rate can be reduced by dephosphorylation, though. Blunt ends also ligate, albeit with lower efficiency than sticky ends.
  10. Their academic careers are usually over, though. Also, I believe he already has written a book. The problem with Wakefield was initially that it was flawed in several areas and he did not follow ethical guidelines. The more recent findings indicate that data (the health records) were actually falsified, which is outright fraud.
  11. Thanks Timo! Just by a rough overview (really hardly reading), it appears to me that they did not consider multiple hypothesis testing. Or at least I could not see it. But on this level I cannot really say that it is really heavily flawed otherwise (but I would need to read in more detail to really be sure on anything).
  12. I think Marat put the facts quite into a wrong context. The main criticism on the US health system is less that it is awful and everyone is dying left and right, but rather that it is more expensive than other developed nations, without providing a better outcome. Regarding education it is probably more that the US was losing a lot of ground on several areas while (I believe) it used to be in the top spot. The difference between self-assessment and actual results may also play a role. According to the OECD survey 2009 USA ranked 30 in mathematics, 23rd in sciences (slight improvement compared to the last, I believe) and 17th in reading (the focus of the last survey). Are the differences significant? Well, they are, though I do not have the values with me right now. What I do have is a statistical test of the countries as difference of the OECD average of each tested element (e.g. reading comprehension). Based on that, the US is roughly OECD-average (not absolutely abysmal) in most areas, except mathematics, where it is significantly below the average. Regarding poverty, I recall someone mentioning that the heritage foundation article was not really reliable for some reasons, but I have to ask (or read up) to figure what it was. Though glancing to the list this is quite laughable, if you know the apartment costs in the these major cities.
  13. There will not be a terrible amount of trouble, but quite a bit of additional paperwork. Essentially you have to demonstrate that what you do is worthwhile, that no viable alternatives exist and that relevant procedures are taken to minimize pain and distress. Normal requirements, especially for NIH funded projects, also include training in that area. Essentially the requirements for the respective animal welfare laws have to be fulfilled (as well as certain other guidelines). These apply to all vertebrates. The ethics committee mostly works with you to fulfill these requirements.
  14. Could you provide the reference and abstract, please?
  15. It would costs far more than a few thousand to accomplish. You would have to first make a transfection construct (i.e. a vector containing GFP or GFP fusion with correct promoters) then transfect and then select for those with successful transfection. Essentially you have to create a mutant that actively expresses GFP (or luciferase for luminescence). While the construction of the vector is relatively trivial (but requires somewhat costly equipment to function efficiently). The actually transfection (i.e. insertion of the vector and hoping for efficient recombination) is a rare event, meaning that you have to screen a lot until you find a cell that got it. Definitely not a very good DIY project.
  16. Well, quite a few vitamins are lipohilic and do not get secreted efficiently. These generally carry the highest risk for overdosing, as they may accumulate to some extent. In many cases and on normal diets many supplements have little beneficial effects. In contrast to what Marat claims, there is little evidence that high doses have wide-ranging beneficial effects (conspiracies aside). Iron is one of those from which many women actually do benefit, though, especially on diet with low iron content. The toxicity is, for the most part low, though one should be careful e.g. in cases of infections or intestine problems, as high levels of available iron can allow bacteria to grow more efficiently. This also goes for pathogenic ones. Also note that adverse effect levels are usually rough estimates. One should try not to use those levels as hard safety limits.
  17. There are a number of finer biochemical characterizations in which binding and subsequent transport (though the latter can essentially only be shown indirectly). Check the annual review: Kaplan BIOCHEMISTRY OF NA,K-ATPASEAnnual Review of Biochemistry Vol. 71: 511-535 (Volume publication date July 2002)
  18. The basic difference is how they are derived. Breeds are, well, bred. Strains usually have smaller defined genomic differences. Note that there is an overlap, as defined strains could be derived from breeding. However, all individuals within a strain are genetically uniform.
  19. Eh, for a research position it is really risky, unless you are well connected. There are not that many research positions available. Truth is that most lab research is done by grad students or postdocs. And the letter only for a limited time (I have seen quite a few engineers without postdocs). Other than that in many jobs you would be more group/ lab leader (i.e. being removed from research) but these positions are usually very competitive. There are also industrial R&D positions, though but apparently the job pool is kind of limited, at least in areas I am familiar with. If you are well connected, it may be worth a try, or at least ask around to look, what kind of positions are really available. Otherwise you may be set yourself to be overqualified for the job you got right now and not be competitive enough compared to the fresh 20-something PhDs (unless your current job gives you some kind of edge, however the edge may be considered dulled after a PhD hiatus).
  20. This is not even the real issue here. AFAIK there was progress in creating tissue from stem cells, but not yet fully functioning organs. Also, getting fully functioning stem cells is non-trivial to begin with. Reversing adult cells to become pluripotent again requires regulatory manipulations which enhances tumorigenesis (as the normal regulation leading to differentiation has to be knocked out). This is very unlikely to be beneficial right now.
  21. Two mechanisms. First is its antibacterial activity, mostly due to the generation of oxidative stress. Second is chemisorption and catalytic removal (the more relevant part here).
  22. Both have to be balanced out. As the exchange is by diffusion a proper gradient for both gases (in opposite directions) have to be maintained. Impeding CO2 transfer would lead to hypercapnia.
  23. Well that is not a particular mystery for the most part. The basic asumption is that due to the equilibrium shift P would subsequently be replaced by As. Normally, this would result in inactive biomolecules and eventually death of the organism.
  24. In many ways gametes are not much different than other highly differentiated cells. Certain signals resulted in the activation of regulatory pathways that eventually led to the formation to their current state (i.e. gamete) and everything that is related to it (including no substantial cell growth etc.). This is true for about any cell type you find. Essentially regulation is the key. This is even the case in unicellular organisms that do not differentiate. Up on certain cues (could be anything starting from nutrient availability, stress or quorum sensing), certain regulatory networks activate/deactivate leading to very different cellular responses, despite having the same genome.
  25. Absolutely not. There is heavy modulation and editing going on before the signal reaches the brain. The way it works is not that there is a specialized cell that can spot a pattern per se (how is it supposed to do it, it only gets a signal and then transfers it). The trick is than the signal reaches an ensemble of cells that are connected in such a way that they cumulative respond to a specific stimulus. In simplified form, imagine a row of cells. The right cells inhibit the cells to their left, whereas the left cells induce the ones right of them. What happens is that if a light source moves from left to the right, the net signal is a very strong one, as the first cell (outermost left) gives out a signal and then increases the output of the neighboring cell when the light reaches it. On the other hand the same cells are non-responsive to movements from right to left. Thus you have a group of cells that are specialized to left-to-right movements. Note that this kind of modulation is, with exceptions, not necessarily located on the retina itself, but also in cells on the way to the brain. Specialized effects as e.g. cells specialized in detecting contrasts or specific patterns and movements are wired like this. The brain only gets a heavily edited version of what is going on in the retina.
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