CharonY

Hmm do you have access to any scanning probe microscopes (e.g. AFM)? Or microscopes at all?

The calculation of the any phage titer is pretty much the same. Essentially you want the plaque forming units (pfu) per ml. What you have to consider is that your original phage suspension is diluted twice. First you usually make a dilution or dilution series prior co-incubation with bacterial cells, and secondly you usually do not mix 1 ml of the whole diluted solution with the cells but only a fraction thereof. So for an example: you dilute your phage suspension 10e-4 you add 1 µl (or 1/1000th of a ml) of the resulting dilution to your bacteria and mix everything with soft agar and count 4 plaques the next day. So your pfu/ml is: 4*10e4*1000=4*10e7 And regarding mass excision, it depends on the purpose of your library. If you want a sample pool in order to make subtractive hybridization, for instance.

Both are structurally as well as functionally unrelated. A signal anchor is both a signal sequence for the translocation as well as the anchor itself. Proteins that are to be attached in the membrane with a GPI anchor first need an N-terminal signal peptide, that is cleaved during the translocation of the protein, and a C-terminal site, the GPI-modification site onto which the GPI-moiety is post-translationally coupled. In other words the GPI modification siteonly only serves as a recognition site for the coupling of the GPI-anchor, but is not involved in translocation, nor does directly attach to the membrane.

Usually this refers to a specific signal sequence that mediates the translocation and insertion of the protein into the membrane of the ER.

Sorry, I almost forgot about this thread. I have here a couple of reviews regarding HGE and pathogenicity islands. To my knowledge most papers dealing with the evolution of CS1 pili focus on its distribution via HGE and its relatedness with other fimbriae (from your OP I gather that you got these papers already). So to speculate about the evolution of it will require the discussion of the spread of pathogenicity islands and other mobile genetic elements. Here are some reviews dealing with this matter, mostly from a genomic perspective. It is important not to get too much entangled into the details but to find the common theme: Lawrence:Horizontal and Vertical Gene Transfer: The Life History of Pathogens in: Russell W, Herwald H (eds): Concepts in Bacterial Virulence. Contrib Microbiol. Basel, Karger, 2005, vol 12, pp 255-271 (DOI: 10.1159/000081699) Binnewies et al. : Funct Integr Genomics. 2006 Jul;6(3):165-85. Manson and Gilmore: Mol Microbiol. 2006 Aug;61(3):555-9. Gal-Mor and Finlay: Cell Microbiol. 2006 Nov;8(11):1707-19.

Beside archaea and bacteria there are also (obligate) anaerobic fungi. But I think that is about all.

That's how digested (or sheared) genomic DNA always looks like. Just approximate how many restriction sites the Drosophila genome might possess, and what sizes these fragments they may have.

I hope these are not prefilled chambers? Those are rather nasty. Cervical dislocation is usually better, but one needs some skill to pull it off (no pun intended). Actually CO2 use is getting much disputed in a number of labs.

Recently I was forced to look into the US health system a bit. I get a premium fee for working at the university as such I only have to pay 50$ if I used an exclusive provider network or 150$ if I want to be able to make choices outside this network. I wonder how expensive health insurance for the average worker is, though. In Germany everyone is required to get an insurance. If you are an employee with a monthly income lower than 3.937,50 € you are automatically with one of the public health insurer, if it is equal or higher you may elect to join a private one. The lesser is more expensive but gives more benefits. Up until now I was in the public system and paid roughly the amount of what I'd pay for a PPO-choice. I do have to add that in Germany some of the stories from the UK (waiting for 3 weeks before one gets an appointment) is unheard of. From what I heard the standard quality and speed with which you get your treatments in Germany is comparable with the USA, though you are treated preferentially if you are privately insured (in Germany). So basing on this it appears that (with the premiums) the US system is cheaper if I only use physician within the network. How well that works out depends of course how large the network is. Other than that there are additional costs: Physician visits: 10$ per visit, 20$ for specialists in the USA; 20€ per 3 months (regardless how many and which physician/specialists you visit) in Germany. So if you have to often consult specialists in Germany you are better off. It is even worse if you have to consult an out of network specialist. Here you have to meed 300$ deductibles and pay 30% of all costs on your own. In Germany it doesn't cost extra if you are referred to another specialist. Preventive care: 10$ (or 30% out of network) in the US; free in Germany These are some points that I'd have to pay out of my pocket and can be easily quantified and does not tell what actually is covered. However it appears that the German insurers appear to cover a bit more. For instance they also pay for treatment of mental illnesses and dental work, whereas in the USA you need yet another insurance.

Ah I see. Thanks for the info!

That is somewhat unlikely. This bacterium would be over 200 microns and thus even longer than eukaryotic cells. From this pic I wouldn't even be sure whether it is organic.

I'd say yes. However it would help if you could indicate the size of the scale that you see in the pic (just stating a 125x magnification does not help per se as the image itself can be enlarged).

I am not following this candidate in any detail but I came across this article http://www.michiganmessenger.com/showDiary.do?diaryId=404 One point was that he is getting support from white supremacist organizations. Granted, this is not his fault per se. However in the article are some quotes, which I find questionable, though I have no idea whether they are authentic. Can anyone comment on this?

Right you are, my mistake. However, I can only reiterate, usually the hypotonic solution does not lyse the cells but merely swells them. You then add fixatives (e.g. acetic acid methanol solution) to maintain the cells in that state and makes the membrane instable. Then you just spread the cells on the slides. As I said, a precise description of your protocol would be helpful for any discussions. Alternatively check this article: Cytometry 2001, Vol 43, p101-109

Do you drop the sample from a slight height onto the slide? Most protocols for blood use hypotonic buffer to lyse the red blood cells. White blood cells are fixed and spread via dropping them onto a slide. If you lyse them beforehand I'd assume that the nucleus should maintain enough coherence to have the chromosomes lie together. In any case the idea is that by dilution and spreading the given nuclei become separated.

Ugh, studying evolution on this level in bacteria can often be a no-joy as HGE can be quite nasty to track. The majority of evolutionary papers in this field thus concentrate on the structure and selection constraints of given domains (e.g. Ravi P. Anantha et al. Infection and Immunity, December 2004, p. 7190-7201, Vol. 72, No. 12). Regarding the mechanisms of transmission, more is known. The operon of encoding the pilus are flanked by IS elements, indicating that this is a kind of genomic island (or islet), as you have already mentioned, moreover it is located on a plasmid, again a mobile genetic vehicle. A nice paper about the requirements on the mobility of this plasmid (pCoo) is this one: Barbara Froehlich et al., Journal of Bacteriology, May 2004, p. 3230-3237, Vol. 186, No. 10. and Journal of Bacteriology, September 2005, p. 6509-6516, Vol. 187, No. 18. While not precisely dealing with CS1 pili this review gives a nice overview about pathogenicity islands in general, something which in principal is also applicapble to the evolution of ETEC strans: Herbert Schmidt and Michael Hensel, Clinical Microbiology Reviews, January 2004, p. 14-56, Vol. 17, No. 1. I think to recall that I should also have some paper about the evolution of pathogenic E. coli strains somewhere, though I am pretty sure that again, the focus is on pathogenicity islands rather than on specific pili. But I'd have to dig a bit for them. I'll get back to you soonish.

Could you post your complete (and precise) protocol? It may be different from those that I know. Also, are you sure that you already lyse the cell in the hyptonic solution or do you just let them swell?

uhmmm... nope? The majority are colorimetric assays (Bradford Lowry etc.) but there are different other methods as well. The method you can use also depends whether you quantify a purified protein extract or a crude extract, for instance.

1) for quantity the dry weight or any other denominator of biomass would be easy to do. Quality is harder to assess. What makes one fruit of better quality to another (for the plant it is only of interest whether the seeds will spread efficiently, for those feeding off the plant taste or energy content might be more important). 2) If it is not in a controlled environment the easiest thing I can think of is a filtering by size e.g. nets of different sizes. 3) uhm... nectar?

The chromosomes between cells are not mixed during the process. Essentially the cells are fixed, spread (so that they don't overlap) and dried. The chromosomes are then effectively immobilized and the nuclei of the different cells are apart from each other.

Psst michael_mr, they are antiporters Also, if that was what confused you, the gradient is built at the expense of energy (ATP).

Nitrate is, under ambient conditions, not gaseous, of course. Hmm, most common gases produced during fermentation are indeed H2, methane and CO2. I don't know what else might be there in significant amounts.

Excellent point. Also I would think that there are quite some differences in the schooling systems between different countries, despite efforts to make them more comparable. Also the title of this thread is a bit misleading as the OP is rather a critique on the schooling system rather the academic system as whole (which quite possibly is even more flawed...)

He doesn't have to die. As Cap'n Refsmat pointed out, he just has to remove himself from the active gene pool. I wonder, though, what would happen if someone deposits semen or egg cells prior sterilization? Probably no award due to technicality.

You got 14 of the 21 people correct, and you did better recognizing the virginity of guys. Overall, you guessed better than 78% of all test takers. Bah if wanted to spot virgin guys I'd just have to go to the informatics class ;P