Department of Biological Sciences, Bowling Green State University, Life Sciences Building, Bowling Green, OH 43403, USA.
J Basic Microbiol. 2010 Jun;50(3):227-31. doi: 10.1002/jobm.200900337.
Marine picoplankton of the genus Synechococcus and Prochlorococcus spp. are widely studied members of the picocyanobacterial clade, composed of unicellular cyanobacteria that dominate pelagic regions of the ocean. Less studied are the related freshwater Synechococcus spp. that similarly dominate the euphotic zone of oligotrophic lakes. Previous work has shown that marine picocyanobacteria harbor a small gene, hcp, that encodes a 62 amino acid protein 100% conserved among all strains examined. The gene is restricted exclusively to the picocyanobacterial lineage. The current study reveals that hcp is also 100% conserved in four freshwater Synechococcus spp. strains isolated from the Laurentian Great Lakes, and that the gene constitutively expressed with genes encoding a ribosomal protein and two tRNA genes. The synteny of the hcp region is also conserved between the marine and freshwater strains. Last, the hcp gene and the organization of the surrounding genetic region has been retained in the reduced genome of a picocyanobacterial endosymbiont of the amoeba Paulinella sp.
海洋微微型浮游植物聚球藻属和原绿球藻属是研究广泛的微微型蓝藻类群的成员，由在海洋浮游区占主导地位的单细胞蓝细菌组成。相关的淡水聚球藻属研究较少，它们同样在贫营养湖泊的透光区占主导地位。以前的研究表明，海洋微微型蓝藻含有一个名为 hcp 的小基因，该基因编码一个由 62 个氨基酸组成的蛋白质，在所有被检测的菌株中完全保守。该基因仅局限于微微型蓝藻谱系。本研究表明，hcp 在从大湖地区采集的四个淡水聚球藻属菌株中也完全保守，并且该基因与编码核糖体蛋白和两个 tRNA 基因的基因组成性表达。海洋和淡水菌株之间的 hcp 区域的基因排列也保持保守。最后，hcp 基因和周围遗传区域的组织在变形虫 Paulinella sp. 的一种微微型蓝藻内共生体的简化基因组中得以保留。
