Menke, S M , Henson, B J , Barnum, S R .
The Evolution of Nitrogen Fixation in Nitrogen Fixing Cyanobacteria Using nifD.
Nitrogen fixation is randomly dispersed throughout prokaryotic lineages raising the question of whether it has been transferred by vertical or lateral transfer, or both. We have used nifD, the gene encoding the alpha-subunit of the enzyme dinitrogenase, to study the evolution of nitrogen fixation in nitrogen fixing cyanobacteria from Subsections I, II, III, IV, and V. DNA sequences were obtained for analysis from representative strains of nonheterocystous strains within Subsection III and combined with sequence data from GenBank. Maximum liklihood was used to obtain phylogenetic trees and compared to 16S rRNA trees. Results show that nifD has evolved through vertical descent for most cyanobacteria with the exception of a possible lateral transfer of the nifD2 gene in Anabaena variabilis. Our data also corroborate previous studies showing that the heterocystous cyanobacteria form a monophyletic lineage within the nonheterocystous cyanobacteria, while the nonheterocystous cyanobacteria are paraphyletic.
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1 - Miami University, Botany
2 - Miami University, Botany, Oxford, Ohio, 45056, USA
Presentation Type: Plant Biology Abstract
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM