The studies on organization and evolution of eukaiyotes based on genome analyses of primitive red alga.

超小型单细胞藻类的小而紧凑的基因组提供了支持光合作用真核生物（包括高等植物）生命的基本和必需基因的信息。本文报道了单细胞红藻merolae 10D 20条染色体的16,520,305个碱基对序列，这是第一个完整的藻类基因组。我们共鉴定出5331个基因，其中至少86.3%表达。这种基因组结构的独特特征包括：除了26个基因外，其余基因都缺乏内含子；维持核仁的核糖体DNA单位只有三个拷贝；两个动力蛋白基因只参与线粒体和质体的分裂。卡尔文循环酶在红藻和绿色植物中保守的马赛克起源支持了单一原生质体内共生存在的假设。肌凝蛋白基因的缺失，加上未表达的肌动蛋白基因，表明细胞分裂的系统更简单。这些结果表明，merolae基因组为研究真核细胞的起源、进化和基本机制提供了一个具有简单基因组成的模式系统。

Small, compact genomes of ultrasmall unicellular algae provide information on the basic and essential genes that support the lives of photosynthetic eukaryotes, including higher plants. We reported the 16,520,305-base-pair sequence of the 20 chromosomes of the unicellular red alga Cyanidioschyzon merolae 10D as the first complete algal genome. We identified 5,331 genes in total, of which at least 86.3% were expressed. Unique characteristics of this genomic structure include: a lack of introns in all but 26 genes; only three copies of ribosomal DNA units that maintain the nucleolus; and two dynamin genes that are involved only in the division of mitochondria and plastids. The conserved mosaic origin of Calvin cycle enzymes in this red alga and in green plants supports the hypothesis of the existence of single primary plastid endosymbiosis. The lack of a myosin gene, in addition to the unexpressed actin gene, suggests a simpler system of cytokinesis. These results indicate that the C. merolae genome provides a model system with a simple gene composition for studying the origin, evolution and fundamental mechanisms of eukaryotic cells.