Beye Martin, Gattermeier Irene, Hasselmann Martin, Gempe Tanja, Schioett Morten, Baines John F, Schlipalius David, Mougel Florence, Emore Christine, Rueppell Olav, Sirviö Anu, Guzmán-Novoa Ernesto, Hunt Greg, Solignac Michel, Page Robert E
Institute of Genetics, Heinrich Heine Universität Duesseldorf, Duesseldorf 40225, Germany.
Genome Res. 2006 Nov;16(11):1339-44. doi: 10.1101/gr.5680406. Epub 2006 Oct 25.
The first draft of the honey bee genome sequence and improved genetic maps are utilized to analyze a genome displaying 10 times higher levels of recombination (19 cM/Mb) than previously analyzed genomes of higher eukaryotes. The exceptionally high recombination rate is distributed genome-wide, but varies by two orders of magnitude. Analysis of chromosome, sequence, and gene parameters with respect to recombination showed that local recombination rate is associated with distance to the telomere, GC content, and the number of simple repeats as described for low-recombining genomes. Recombination rate does not decrease with chromosome size. On average 5.7 recombination events per chromosome pair per meiosis are found in the honey bee genome. This contrasts with a wide range of taxa that have a uniform recombination frequency of about 1.6 per chromosome pair. The excess of recombination activity does not support a mechanistic role of recombination in stabilizing pairs of homologous chromosome during chromosome pairing. Recombination rate is associated with gene size, suggesting that introns are larger in regions of low recombination and may improve the efficacy of selection in these regions. Very few transposons and no retrotransposons are present in the high-recombining genome. We propose evolutionary explanations for the exceptionally high genome-wide recombination rate.
利用蜜蜂基因组序列初稿和改进的遗传图谱来分析一个基因组，该基因组的重组水平（19厘摩/兆碱基）比之前分析的高等真核生物基因组高10倍。极高的重组率在全基因组范围内分布，但变化幅度达两个数量级。对染色体、序列和基因参数与重组关系的分析表明，局部重组率与到端粒的距离、GC含量以及简单重复序列的数量有关，这与低重组基因组的情况相同。重组率并不随染色体大小而降低。在蜜蜂基因组中，平均每个染色体对在减数分裂时发生5.7次重组事件。这与广泛的分类群形成对比，这些分类群每个染色体对的重组频率约为1.6且较为一致。重组活性过高并不支持重组在染色体配对过程中稳定同源染色体对方面的机制作用。重组率与基因大小相关，这表明在低重组区域内含子更大，可能会提高这些区域的选择效率。在高重组基因组中存在极少的转座子且没有逆转座子。我们对全基因组范围内极高的重组率提出了进化方面的解释。
