Giovannoni, S. Oregon State University, giovanns@bcc.orst.edu
Rappe, M. Station Biologique, rappe@sbr.sb-roscoff.fr
Lanoil, B. Cal Tech, lanoilb@gps.caltech.edu

 
WHAT WE HAVE LEARNED FROM A DECADE OF STUDYING PICOPLANKTON DIVERSITY USING MOLECULAR TECHNIQUES, AND THE APPLICATION OF THIS KNOWLEDGE TO THE IDENTIFICATION OF SINGLE CELLS
 
Since the first ribosomal RNA gene sequences from uncultured picoplankton were reported in 1990, 616 prokaryotic gene clones from seawater samples have been identified. Some conclusions from these studies are: 1) the most abundant rDNA genes recovered do not correspond to cultured species; 2) marineArchaea are abundant, and almost invariably fall within two phylogenetic groups; 3) 80% of marine Bacteria clones fall among nine phylogenetic groups; 4) these phylogenetic groups form clusters of related genes rather than single lineages; 5) in some cases the sublineages of gene clusters have different depth-specific distributions; these may represent different species; 6) the major marine prokaryotic groups appear to have cosmopolitian distributions; 7) particle-associated and freely-suspended marine prokaryotes are different; 8) stratification of bacterioplankton populations is typical of the ocean surface layer. The above findings provide a valuable resource of information that can be applied to the identification of single cells using oligonucleotides complementary to rRNAs. However, this work has advanced surprisingly slowly in part because of the small size and slow growth rate of many picoplankton, and because the phenomenom of gene clusters has made it necessary to analyze larger amounts of gene sequence information for the purpose of designing effective probes. In recent work better oligonucleotide probes for rRNAs have been designed, there have been advances in fluorochrome chemistry, and alternative DNA-dependent techniques for identifying cells have emerged, including in situ PCR and Bacterial Chromosomal Painting (BCP).
 
Day: Monday, Feb. 1
Time: 04:15 - 04:30pm
Location: Sweeney Center
 
Code: SS41MO0415S