Ecotypes of Prochlorococcus and Synechococcus
The unicellular marine Cyanobacteria Prochlorococcus and Synechococcus are closely related genera that are extremely abundant in open ocean waters and account for a significant portion of global primary production. Both groups consist of multiple physiological and genetic types. We are using parts of the ribosomal RNA operon as a neutral marker to investigate the phylogenetic relationships of strains within each genus, and attempt to correlate the genetic diversity with observed physiological diversity. We have developed real-time quantitative PCR assays to specifically enumerate ecotypes of both Prochlorococcus and Synechococcus in natural samples. By examining the distributions of the different ecotypes over a variety of seasonal and spatial scales we hope to understand the environmental factors that have driven the genetic differentiation we observe. Nathan Ahlgren has led the development of the Q-PCR assays and Cheryl Williams also contributes to these questions. Funding from the National Science Foundation.
Relevant Publications
Ahlgren, N. A. and G. Rocap. 2006. Culture isolation and culture-independent clone libraries reveal new marine Synechococcus ecotypes with distinctive light and N physiologies. Applied and Environmental Microbiology 72: 7193-7204. PDF file (752 kb)
Ahlgren, N. A., G. Rocap, and S. W. Chisholm. 2005. Measurement of Prochlorococcus ecotypes using real-time polymerase chain reaction reveals different abundances of genotypes with similar light physiologies Environmental Microbiology doi: 10.1111/j.1462-2920.2005.00910.x PDF file (257 kb)
Rocap, G., D. L. Distel, J. B.Waterbury and S. W. Chisholm. 2002. Resolution of Prochlorococcus and Synechococcus ecotypes using 16S-23S rRNA internal transcribed spacer (ITS) region sequences. Applied and Environmental Microbiology, 68: 1180-1191. PDF file (362 kb)
Rocap, G., L. R. Moore and S. W. Chisholm. 1999. Molecular Phylogeny of Prochlorococcus ecotypes. in Marine Cyanobacteria, L. Charpy and A. W. D. Larkum ed. Bulletin de líInstitute Océanographique, Monaco, special issue No. 19. pp. 107-116. PDF file (548 kb)
Rocap, G., L. R. Moore and S. W. Chisholm. 1999. Molecular Phylogeny of Prochlorococcus ecotypes. in Marine Cyanobacteria, L. Charpy and A. W. D. Larkum ed. Bulletin de líInstitute Océanographique, Monaco, special issue No. 19. pp. 107-116. PDF file (548 kb)
Moore, L. R., G. Rocap and S. W. Chisholm. 1998. Physiology and Molecular Phylogeny of Coexisting Prochlorococcus ecotypes. Nature 393: 464-467. PDF file (345 kb)