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dc.contributor.authorRocap, Gabrielle  Concept link
dc.contributor.authorDistel, Daniel L.  Concept link
dc.contributor.authorWaterbury, John B.  Concept link
dc.contributor.authorChisholm, Sallie W.  Concept link
dc.date.accessioned2005-11-22T18:45:33Z
dc.date.available2005-11-22T18:45:33Z
dc.date.issued2002-03
dc.identifier.citationApplied and Environmental Microbiology 68 (2002): 1180-1191en
dc.identifier.urihttps://hdl.handle.net/1912/171
dc.descriptionAuthor Posting. © American Society for Microbiology, 2002. This article is posted here by permission of American Society for Microbiology for personal use, not for redistribution. The definitive version was published in Applied and Environmental Microbiology 68 (2002): 1180-1191, doi:10.1128/AEM.68.3.1180-1191.2002.
dc.description.abstractCultured isolates of the marine cyanobacteria Prochlorococcus and Synechococcus vary widely in their pigment compositions and growth responses to light and nutrients, yet show greater than 96% identity in their 16S ribosomal DNA (rDNA) sequences. In order to better define the genetic variation that accompanies their physiological diversity, sequences for the 16S-23S rDNA internal transcribed spacer (ITS) region were determined in 32 Prochlorococcus isolates and 25 Synechococcus isolates from around the globe. Each strain examined yielded one ITS sequence that contained two tRNA genes. Dramatic variations in the length and G+C content of the spacer were observed among the strains, particularly among Prochlorococcus strains. Secondary-structure models of the ITS were predicted in order to facilitate alignment of the sequences for phylogenetic analyses. The previously observed division of Prochlorococcus into two ecotypes (called high and low-B/A after their differences in chlorophyll content) were supported, as was the subdivision of the high-B/A ecotype into four genetically distinct clades. ITS-based phylogenies partitioned marine cluster A Synechococcus into six clades, three of which can be associated with a particular phenotype (motility, chromatic adaptation, and lack of phycourobilin). The pattern of sequence divergence within and between clades is suggestive of a mode of evolution driven by adaptive sweeps and implies that each clade represents an ecologically distinct population. Furthermore, many of the clades consist of strains isolated from disparate regions of the world's oceans, implying that they are geographically widely distributed. These results provide further evidence that natural populations of Prochlorococcus and Synechococcus consist of multiple coexisting ecotypes, genetically closely related but physiologically distinct, which may vary in relative abundance with changing environmental conditions.en
dc.description.sponsorshipThis work was supported by an NSF graduate fellowship to G.R., by NASA grant NAG5-3727 and NSF grant OCE9820035 to S.W.C., and by NSF grant OCE9315895 to D.L.D. and J.B.W.en
dc.format.extent370041 bytes
dc.format.mimetypeapplication/pdf
dc.language.isoen_USen
dc.publisherAmerican Society for Microbiologyen
dc.relation.urihttps://doi.org/10.1128/AEM.68.3.1180-1191.2002
dc.subjectMarine cyanobacteriaen
dc.subjectProchlorococcusen
dc.subjectSynechococcusen
dc.subjectInternal transcribed spacer (ITS)en
dc.subjectCoexisting ecotypesen
dc.titleResolution of Prochlorococcus and Synechococcus ecotypes by using 16S-23S ribosomal DNA internal transcribed spacer sequencesen
dc.typeArticleen
dc.identifier.doi10.1128/AEM.68.3.1180-1191.2002


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