Comparative genomics of chromosome rearrangement in vertebrates based on medaka genome information

脊椎动物基因组大小的进化通常受到非编码序列变化的影响，小核苷酸序列的插入和缺失（indels）以及重复元件的扩增被认为是负责的。在本项目中，我们特别比较了两种鱼的基因组DNA序列，青鳉（Oryzias latipes）和河豚（Takifugu rubripes），这两种鱼的基因组大小相差两倍（800 Mb对400 Mb）。我们确定了一个连续的DNA序列790 kb的青鳉染色体LG22（连锁群22）。该序列在两种鱼类之间是共同的，并且被发现富含各种重复元件，包括许多类型的未分类的低拷贝重复，所有这些都占基因组大小差异的一半以上（54%）。这些结果有力地表明，重复元件的扩增和indel的编译是促进基因组大小变化的主要驱动力。

Evolution of the genome size in vertebrates is often affected by changes in the noncoding sequences, for which insertions and deletions (indels) of small nucleotide sequences and amplification of repetitive elements are considered responsible. In this project, we especially compared the genomic DNA sequences of two kinds of fish, medaka (Oryzias latipes) and fugu (Takifugu rubripes), which show two-fold difference in the genome size (800 Mb vs. 400 Mb). We determined a contiguous DNA sequence of 790 kb from the medaka chromosome LG22 (linkage group 22). The sequence was aligned common between two fishes, and were found abundant in various repetitive elements including many types of unclassified low copy repeats, all of which accounted for more than a half (54%) of the genome size difference. These results strongly indicated that amplification of repetitive elements and compilation of indels are major driving forces to facilitate changes in the genome size.