All multicellular species SC79 molecular weight studied here are closely related, and species capable of terminal differentiation form a monophyletic group. Comparisons of our study to previous findings show high similarities. Our results agree with a comparative phylogenomics approach used by Swingley et al., a consensus tree of concatenated sequences presented by Blank and Sànchez-Baracaldo , and, are highly similar to 16S rRNA analyses conducted by Schirrmeister et al.. Using
a larger taxon set , we previously inferred polyphyletic groupings of undifferentiated multicellular species belonging to section III. This however is not deducible from the taxonomically more limited full genome data set used in the present study. In cyanobacteria 16S rRNA sequences were highly conserved within a genome. Three species showed minor nucleotide differences. The two 16S rRNA copies of Microcystis aeruginosa CA4P ic50 differed by four ‘single nucleotide polymorphisms’ (SNPs), in Cyanothece sp. PCC 7424 one SNP was detected, and in Nostoc punctiforme one 16S copy possessed two SNPs. The differences are
visualized in a molecular distance matrix in Figure 4. 16S rRNA copies within species were identical for the majority of taxa (shown in yellow) and can be clearly distinguished from gene copies belonging to different species. Temsirolimus nmr Furthermore, using the whole dataset we calculated mean distances within strains (d W ) and between strains (d B ). Results are presented in Table 2. Significance of differences in sequence distances found within and between cyanobacterial strains were estimated using bootstrap re-sampling of the original data set. Distributions
of the resulting mean distances are displayed in Additional files 4 and 5. For each distribution, an see more overall mean distance was calculated ( ). Mean distance of 16S rRNA sequences within species (d W =0.0001) is significantly smaller than between species (d B =0.14; Table 2). 95% confidence intervals of distributions obtained by re-samplings do not overlap. Although previous studies have claimed that variation within 16S rRNA sequences might affect reliability of this gene as a taxonomic marker [10, 34], this was not found for genera used in this study. Rather, the extreme sequence conservation of 16S rRNA gene copies from the same species supports 16S rRNA as a reliable genetic marker for the taxa analyzed here. Figure 4 Distance matrix of cyanobacterial 16S rRNA sequences. Distance matrix between 16S rRNA genes estimated based on K80 substitution model. 16S rRNA gene copy numbers range from one to four per cyanobacterial genomes studied. White lines separate sequence copies of different species. 16S rRNA sequences are highly conserved within species.