GE246 reading for next Monday (March 1):
Diversity-generating retroelements. MEDHEKAR B (2007) Current Opinion in Microbiology.
‘The ancient virus world and evolution of cells’. Koonin, E.V. et al. (2006) Biol. Direct 1-29

BIOLOGY SEMINAR THIS WEEK:
"Self vs. Non-self Discrimination during CRISPR Immunity against Horizontal Gene Transfer"
Wednesday, Feb 24 4:00 PM
Luciano Marraffini
General Biology Seminar
119 Kerckhoff
Department of Molecular Biophysics and Biochemistry Northwestern University

Faculty of 1000 review:
This thorough study of viral dynamics in marine sediments constitutes a major advancement in understanding the roles of viruses in microbial communities and ecosystems. The picture emerging from more than 200 sediment samples taken in four distinct sea basins is that viral production and virus-mediated bacterial mortality are extraordinarily high and increase with water depth, thus extending the now well established significance of virioplankton to marine sediments, especially in the deep sea, where a very large fraction of the Earth’s prokaryotes resides. Similar observations have been made in smaller-scale studies of other marine sediments; however, the results contrast sharply with the lack of significant directly detectable viral infection in freshwater benthic habitats, which had fostered speculation that the roles of viruses in benthic systems could be far less important than in pelagic environments.

Faculty of 1000 review of Heidelberg et al 2009 article:

These authors present a fascinating story on the warfare between viruses and bacteria within a microbial mat community.
Comparative analysis of the highly variable CRISPR spacer or ‘viritope’ sequences present in the genomes of two cyanobacteria isolated from a hot spring microbial mat community and in the metagenome of the viruses within the mat provided insight into the population dynamics and the co-evolution of the cyanobacteria and their viruses. These findings might further our understanding on the role of viruses in shaping microbial diversity, which is a highly unexplored topic.

No seminar meeting on Monday (Holiday). In lieu of a reading next week, we will have a presentation by Jed Fuhrman (USC) on Wed the 17th. I will be providing lunch at noon (pizza) for the seminar participants if you would like to come early and talk with Jed. Seminar will start at 1:00. Please send me a email if you plan to come for lunch.

Good review by Bonnie Bassler