Nature发表了黑青斑河豚（Tetraodon nigroviridis）的基因组序列草图。黑青斑河豚和相关的红鳍多纪（Takifugu rubripes）作为研究工具对演化遗传学家来说有很多优势，更不用说它们是已知最小的脊椎动物基因组了。
被认为鱼类所没有的关键基因现在已在黑青斑河豚身上识别出来，与人类基因组所做的比较显示出900个以前没有标记的基因。在其与哺乳动物分化之后的某个时候，在硬骨鱼类中发生了整基因组复制。
与人类和小鼠基因组所做的比较显示出最早有骨基因组（在哺乳动物出现前已知最近的有骨鱼）的基本结构，这是一个紧凑型基因组，只有12个染色体。
河豚是一种颜色鲜艳的鱼类。新近公布的河豚基因组图谱表明有骨鱼和人类的共有的脊椎动物祖先只有12对染色体，但后来鱼类在与人类分化开后将基因组扩增了一倍。研究人员将这些结果发表在10月20日的Nature上。
绿点的黑青斑河豚（Tetraodon nigroviridis）是大约20000种有鱼鳍鱼类中的一种。大约在4500万年前，鳍鱼的祖先与其它脊椎动物如青蛙、小鸡和人类等家族分化开来。对其它鳍鱼的基因的研究表明在鳍鱼进化的过程中，整个基因组发生了复制（1998年11月27日Science，1711页）。但是由于缺乏证据，人们对这种观点存在争议。
现在，麻省理工和哈佛大学的研究人员已经完成了这种河豚基因组（脊椎动物中最小的基因组）的测序工作，并且找出了具有数百个重复的基因的染色体区域。当研究人员将超过6000个河豚基因的位置与人类基因组中相应的基因的位置进行比较时发现，人类染色体中的一个染色体区域与河豚基因组中的两个区域相符合。这意味着人类和河豚的共同祖先只有12条染色体，并且在鳍鱼进化过程中整个基因组被复制。
河豚基因组较小表明在基因组被复制后又发生了大量的删减。这些分析结果让研究人员对基因组进化的过去和将来有了一定的了解。
Tetraodon nigroviridis is a freshwater puffer fish with the smallest known vertebrate genome. Here, we report a draft genome sequence with long-range linkage and substantial anchoring to the 21 Tetraodon chromosomes. Genome analysis provides a greatly improved fish gene catalogue, including identifying key genes previously thought to be absent in fish. Comparison with other vertebrates and a urochordate indicates that fish proteins have diverged markedly faster than their mammalian homologues. Comparison with the human genome suggests 900 previously unannotated human genes. Analysis of the Tetraodon and human genomes shows that whole-genome duplication occurred in the teleost fish lineage, subsequent to its divergence from mammals. The analysis also makes it possible to infer the basic structure of the ancestral bony vertebrate genome, which was composed of 12 chromosomes, and to reconstruct much of the evolutionary history of ancient and recent chromosome rearrangements leading to the modern human karyotype.
Figure Synteny maps. a, For each Tetraodon chromosome, coloured segments represent conserved synteny with a particular human chromosome. Synteny is defined as groups of two or more Tetraodon genes that possess an orthologue on the same human chromosome, irrespective of orientation or order. Tetraodon chromosomes are not in descending order by size because of unequal sequence coverage. The entire map includes 5,518 orthologues in 900 syntenic segments. b, On the human genome the map is composed of 905 syntenic segments. See Supplementary Information for the synteny map between Tetraodon and mouse (Supplementary Fig. S11).
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