CNRS UMR7238, Laboratoire de Génomique des Microorganismes, Université Pierre-et-Marie-Curie, Institut des Cordeliers, 15 rue de l'École-de-Médecine, 75006 Paris, France.
C R Biol. 2011 Aug-Sep;334(8-9):629-38. doi: 10.1016/j.crvi.2011.05.011. Epub 2011 Jul 5.
We studied synteny conservation between 18 yeast species and 13 vertebrate species in order to provide a comparative analysis of the chromosomal plasticity in these 2 phyla. By computing the regions of conserved synteny between all pairwise combinations of species within each group, we show that in vertebrates, the number of conserved synteny blocks exponentially increases along with the divergence between orthologous protein and that concomitantly; the number of genes per block exponentially decreases. The same trends are found in yeasts but only when the mean protein divergence between orthologs remains below 36%. When the average protein divergence exceeds this threshold, the total number of recognizable synteny blocks gradually decreases due to the repeated accumulation of rearrangements. We also show that rearrangement rates are on average 3-fold higher in vertebrates than in yeasts, and are estimated to be of 2 rearrangements/Myr. However, the genome sizes being on average 200 times larger in vertebrates than in yeasts, the normalized rates of chromosome rearrangements (per Mb) are about 50-fold higher in yeast than in vertebrate genomes.
我们研究了 18 种酵母物种和 13 种脊椎动物物种之间的同线性保守性，以便对这两个门的染色体可塑性进行比较分析。通过计算每个组内所有物种对之间保守同线性区域的数量，我们表明，在脊椎动物中，与同源蛋白的分歧成正比，保守同线性块的数量呈指数增长；每个块中的基因数量呈指数下降。在酵母中也发现了同样的趋势，但前提是直系同源蛋白之间的平均蛋白质分歧保持在 36%以下。当平均蛋白质分歧超过此阈值时，由于重排的反复积累，可识别的同线性块的总数逐渐减少。我们还表明，脊椎动物中的重排率平均比酵母高 3 倍，估计为每百万年 2 次重排。然而，由于脊椎动物的基因组大小平均比酵母大 200 倍，因此酵母中染色体重排的归一化率（每 Mb）比脊椎动物基因组高约 50 倍。
