title: Extreme conservation and non-neutral evolution of the cpmA Circadian locus in a globally distributed Chroococcidiopsis sp. from naturally stressful habitats.
abstract: Cyanobacteria are among the most ancient organisms known to have circadian rhythms. The cpmA gene is involved in controlling the circadian output signal. We studied polymorphism and divergence of this gene in six populations of a stress-tolerant cyanobacterium, Chroococcidiopsis sp., sampled in extreme habitats across the globe. Despite high haplotype diversity (0.774), nucleotide diversity of cpmA is very low (π = 0.0034): the gene appears to be even more conserved than housekeeping genes. Even though the populations were sampled thousands kilometers apart, they manifested virtually no genetic differentiation at this locus (F(ST) = 0.0228). Using various tests for neutrality, we determined that evolution of cpmA significantly departures from the neutral model and is governed by episodic positive selection.
authors: School of Biological Sciences, University of Hong Kong, Pokfulam, Hong Kong SAR, People's Republic of China.
authors: Volodymyr
authors: V
authors: Dvornyk
authors: Akhee Sabiha
authors: AS
authors: Jahan
mesh_terms: D001426:Bacterial Proteins; D001483:Base Sequence; D056925:Circadian Rhythm Signaling Peptides and Proteins / Q000235:genetics*; D003001:Cloning, Molecular; D017124:Conserved Sequence / Q000235:genetics; D000458:Cyanobacteria / Q000235:genetics*; D017931:DNA Primers / Q000235:genetics; D017753:Ecosystem; D019143:Evolution, Molecular; D014644:Genetic Variation; D005828:Genetics, Population; D006239:Haplotypes / Q000235:genetics; D016013:Likelihood Functions; D008957:Models, Genetic; D008969:Molecular Sequence Data; D012641:Selection, Genetic; D017422:Sequence Analysis, DNA; D017385:Sequence Homology
chemical_list: D001426:Bacterial Proteins; D056925:Circadian Rhythm Signaling Peptides and Proteins; D017931:DNA Primers; C119580:cpmA protein, Synechococcus sp.