Genetic Diversity and Ecotypic Differentiation in the Marine Cyanobacteria Prochlorococcus and Synechococcus
Abstract
Primary production in the open ocean is dominated by the closely related cyanobacterial genera Prochlorococcus and Synechococcus. This thesis explores the relationship between physiological and genetic diversity in cultured isolates of Prochlorococcus and Synechococcus and examines genetic diversity in natural cyanobacterial populations to better understand the ecology of this globally important clade. The analysis of 165 ribosomal RNA gene (rDNA) sequences of a spectrum of Prochlorococcus isolates from the world's oceans suggested that Prochlorococcus could be divided into two distinct ecotypes, designated high and low B/A because of their differing chl b/a2 ratios. To further resolve the ecotypes, the internal transcribed spacer region (ITS) between the 16 and 23S rRNAs was sequenced in isolates of Prochlorococcus and Synechococcus. Phylogenetic analysis identified ten sequence clusters, four of Synechococcus and six of Prochlorococcus, each of which likely corresponds to an ecologically distinct population. Genetic diversity of natural populations of Prochlorococcus and Synechococcus was investigated in summer and winter waters of the Sargasso Sea by constructing clone libraries from PCR amplified ITS sequences, which were screened by restriction fragment length polymorphism (RFLP).
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 01, 2000
- Accession Number
- ADA384722
Entities
People
- Gabrielle Rocap
Organizations
- Massachusetts Institute of Technology