Friday, May 25, 2007

Highlights of ASM 2007 -- May 23 and May 24

On Wednesday, I attended two sessions -- one on adaptive landscapes in the morning and another on integrating ecology and evolution into the teaching of microbiology in the afternoon.

The highlight of the morning session was probably the talk by Paul Turner on the effect of co-infection on fitness variance in bacteriophage ϕ6 (which infects Pseudomonas). I hadn't heard about ϕ6 prior to this talk, but it is really quite interesting because much like the influenza virus, it is an RNA virus with multiple segments. When two or more ϕ6 phages infect the same cell, the progeny viruses can have a mixture of segments derived from different "parents". In theory, co-infection could act as a crutch for less fit viruses, as some of their (partial) progeny could be of higher fitness. Turner and colleagues showed that this indeed what happens An earlier version of the work he presented was written up in an article in PLoS Biology.

You might legitimately ask why I attended the afternoon session on integrating ecology and evolution into teaching microbiology (as I don't teach), but maybe I was just drawn to the name of Jo Handelsman, who is rightly renowned for both her teaching and her active research program. Jo is into metagenomics and microbial biodiversity these days, and she talked about how to explain the use of sampling to estimate diversity to undergraduates. She believes that it is easier to start out with concrete simple examples. One of her techniques is to use bags of candies that have different distributions of colors to show that one can underestimate diversity in populations with a majority species (If one draws out three candies and they are all green, one may be tempted to assume that all of the candies are green, perhaps incorrectly).

Thursday morning I had to attend my poster on positive selection in Geobacter. Most people stopping by were more interested in learning how to use PAML in their own systems than in the results, but that was okay as my results are fairly preliminary anyway.

In the afternoon, I attended a session on predation of bacteria. I've long been interested in predators of bacteria (particularly bacterial predators of bacteria such as Bdellovibrio). These days there is quite a battle going on over which of the three main predators (phage, protists, and bacterial predators) is the most important in regulation of bacterial populations in nature. Henry Williams (with whom last year I wrote a grant proposal to sequence environmental isolates of Bdellovibrio-like organisms, unfortunately not funded) gave an interesting talk on comparing the effects of phage versus Bdellovibrio-like predation. He came up with the conclusion that Bdellovibrio and friends are more important because their titers after controlled predation go up several orders of magnitude more than do phage, and this he explained as a result of Bdellovibrio being motile and phages not.

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