Moore Christa E, Archibald John M
The Canadian Institute for Advanced Research, Program in Integrated Microbial Biodiversity, Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Nova Scotia, B3H 1X5, Canada.
Annu Rev Genet. 2009;43:251-64. doi: 10.1146/annurev-genet-102108-134809.
Nucleomorphs are the remnant nuclei of algal endosymbionts in cryptophytes and chlorarachniophytes, two evolutionarily distinct unicellular eukaryotic lineages that acquired photosynthesis secondarily by the engulfment of red and green algae, respectively. At less than one million base pairs in size, nucleomorph genomes are the most highly reduced nuclear genomes known, with three small linear chromosomes and a gene density similar to that seen in prokaryotes. The independent origin of nucleomorphs in cryptophytes and chlorarachniophytes presents an interesting opportunity to study the reductive evolutionary forces that have led to their remarkable convergence upon similar genome architectures and coding capacities. In this article, we review the current state of knowledge with respect to the structure, function, origin, and evolution of nucleomorph genomes across the known diversity of cryptophyte and chlorarachniophyte algae.
核质体是隐藻和绿藻虫中藻类内共生体的残余细胞核，这两个在进化上截然不同的单细胞真核生物谱系分别通过吞噬红藻和绿藻而次生获得光合作用。核质体基因组大小不到一百万个碱基对，是已知的高度简化的核基因组，有三条小的线性染色体，其基因密度与原核生物相似。隐藻和绿藻虫中核质体的独立起源为研究导致它们在基因组结构和编码能力上显著趋同的简化进化力量提供了一个有趣的机会。在本文中，我们综述了关于隐藻和绿藻虫藻类已知多样性中核质体基因组的结构、功能、起源和进化的当前知识状态。
