FIG. 6.

Phylogenetic tree showing the relationships of the AMBITION cruise CYA359F-NITRO821R environmental 16S rDNA sequences. Each AMBITION cruise environmental sequence is referred to by station number, depth of sampling, and clone (cl.) number. The tree was constructed by the neighbor-joining method with Jukes-Cantor correction based on nearly full-length 16S rDNA sequences from marine and freshwater cyanobacteria. The percentages of bootstrap replicates supporting the branching order are indicated at the nodes. Partial sequences (e.g., sequences of the 462-bp product amplified by the CYA359F-NITRO821R primer set and other sequences <1,190 nucleotides long) were added to the tree by using a maximum-parsimony option within ARB. The cyanobacterium Gloeobacter violaceus PCC7421 was used as a root. The scale bar represents the equivalent of 0.1 substitution per nucleotide.