Rocap Gabrielle, Larimer Frank W, Lamerdin Jane, Malfatti Stephanie, Chain Patrick, Ahlgren Nathan A, Arellano Andrae, Coleman Maureen, Hauser Loren, Hess Wolfgang R, Johnson Zackary I, Land Miriam, Lindell Debbie, Post Anton F, Regala Warren, Shah Manesh, Shaw Stephanie L, Steglich Claudia, Sullivan Matthew B, Ting Claire S, Tolonen Andrew, Webb Eric A, Zinser Erik R, Chisholm Sallie W
School of Oceanography, University Of Washington, Seattle, Washington 98195, USA.
Nature. 2003 Aug 28;424(6952):1042-7. doi: 10.1038/nature01947. Epub 2003 Aug 13.
The marine unicellular cyanobacterium Prochlorococcus is the smallest-known oxygen-evolving autotroph. It numerically dominates the phytoplankton in the tropical and subtropical oceans, and is responsible for a significant fraction of global photosynthesis. Here we compare the genomes of two Prochlorococcus strains that span the largest evolutionary distance within the Prochlorococcus lineage and that have different minimum, maximum and optimal light intensities for growth. The high-light-adapted ecotype has the smallest genome (1,657,990 base pairs, 1,716 genes) of any known oxygenic phototroph, whereas the genome of its low-light-adapted counterpart is significantly larger, at 2,410,873 base pairs (2,275 genes). The comparative architectures of these two strains reveal dynamic genomes that are constantly changing in response to myriad selection pressures. Although the two strains have 1,350 genes in common, a significant number are not shared, and these have been differentially retained from the common ancestor, or acquired through duplication or lateral transfer. Some of these genes have obvious roles in determining the relative fitness of the ecotypes in response to key environmental variables, and hence in regulating their distribution and abundance in the oceans.
海洋单细胞蓝细菌原绿球藻是已知最小的能进行产氧光合作用的自养生物。在数量上，它在热带和亚热带海洋的浮游植物中占主导地位，并且对全球光合作用有很大贡献。在这里，我们比较了原绿球藻谱系中进化距离跨度最大且生长所需的最小、最大和最适光照强度不同的两个原绿球藻菌株的基因组。适应高光的生态型具有已知的任何产氧光合生物中最小的基因组（1,657,990个碱基对，1,716个基因），而其适应低光的对应菌株的基因组则明显更大，为2,410,873个碱基对（2,275个基因）。这两个菌株的比较基因组结构揭示了动态的基因组，它们不断响应各种选择压力而发生变化。尽管这两个菌株有1,350个共同基因，但仍有相当数量的基因不共享，这些基因或是从共同祖先那里差异化保留下来的，或是通过基因复制或横向转移获得的。其中一些基因在决定生态型对关键环境变量的相对适应性方面具有明显作用，从而在调节它们在海洋中的分布和丰度方面发挥作用。
