Off topic: I'm pretty sure I don't want to know more about "ricewater stool", but is it true that the human body contains more bacterial cells in it than human cells?
Having dealt with copepods before I know that they are voracious and indescriminate eaters. They basically shovel into their mouth-parts anything that will fit. Consequently they are also good excretors, bundling up their waste in a little fecal pellet that settles to the bottom of the water column. They do eat mosquito larvae (some anyway) so they aren't all bad. And they are the most important source of protein in the oceans.
People who study them are called copepodologists, and you have to admit, that's a cute name.
Wow Tara..
I kinda had my doubts about 'microbial ecology' before - I always imagined these guys just living in whatever kind of soup they found themselve in.
The idea that the presence of a polymer ,in the form of the shell of a higher organism, can speed up their evolution is really quite mindblowing.
Like a lot of things I expect something that seems unusual will turn out to be commonplace and even the norm - just depends how hard you look..
Thanks again
Dave,
Yep. Good overview of it here.
Dean,
Thw whole field has really been opened up by the increase in interest in biofilms. It's moving more toward a study of how bacteria actually are found in nature, rather than how we typically study them in the lab (pure cultures, planktonic [free-living] cells, etc.) Obviously the latter still provides us with a lot of useful information, but if we want a better view of how bacteria *really* affect our world, we need to use a more realistic ecologic model. Luckily, people smarter than myself are working on this. 
Oh for a field guide and a field electron microscope!
YOWZA...Looks like they outnumber us cell-to-cell 10-1 at least. Thanks Tara.
This truly is a bacterial planet, and we are just convenient transportation and a snack along the way.
> I'm pretty sure I don't want to know more about "ricewater stool"
You'll find out when you prep for a colonoscopy.
Okay, Tara, this is way over my head, but I'll ask anyway -- how does the presence of chitin aid the takeup of DNA by V. cholerae? Is is because the bacteria are simply more concentrated on the chitin surface, so that there are more possibilities of gene transfer? Or does the polymer itself play some role in the ability of the bacterium to acquire a new gene? Thanks.
They don't know exactly, but here's their line of reasoning. The presence of chitin was shown to induce the formation of a type of pili (extensions of the bacterial cell, like little bacterial arms) that had previously been linked to competence in other species (type IV pili, if anyone's interested). I'm not familiar with exactly how these affect DNA uptake, though. They are involved in protein uptake, so I'm not sure if they just act as a micro-tunnel through which DNA can travel from the external environment into the bacterium. They also note in the study that a regulatory gene, hapR, which up-regulates a DNA binding protein, was also required for competence, so I'm not sure how much of the effect is due to the pilus alone or the combo of the pilus + DNA binding protein.
Tara,
I can help with the competence issue. It has been well studied in pneumococcus and B. subtilis. In subtilis, there is a complex machinery for taking up single stranded DNA from the environment. The most likely explanation for the linkage of Type IV pili to competence is genetic linkage of the pilin and associated regulatory genes to the competence genes. I don't know that much about pili, but in conjugation, they are not associated with DNA uptake, but only with cell-cell contact. Type IV pili have been associated with motility (Neisseria?) and with virulence. Of course, the mechanism of DNA uptake in V. cholerae may be different than in the two G+'s I mentioned.
As an aside, it has been very well shown in pneumococcus that quorum sensing is integral to competence. Is that true in Group B Strep as well? It could also be true in V. cholerae, as quorum sensing has been shown to be important in several facets of that bug's life as well. Cheers.
Just to follow-up, that is a beautiful paper. Pretty much everything you could possibly ask for is answered in it, in very simple, elegant experiments. Something for the young experimentalist to aspire to!
Paul,
Thanks for the additional information. As far as GBS, there's almost nothing in the literature about either competence or quorum sensing in this bacterium. In V. cholera, it looks from their supplementary figure S2 that cell density does indeed play a role via the previously mentioned hapR.
And I agree, it is a very nice paper.
Commenting by HaloScan
