Calderón P L, Pigozzi M I
Centro de Investigaciones en Reproducción, Facultad de Medicina, Paraguay 2155-piso 10, C1121ABG, Buenos Aires, Argentina.
Chromosome Res. 2006;14(6):605-12. doi: 10.1007/s10577-006-1059-0. Epub 2006 Sep 14.
Using immunolocalization of the mismatch-repair protein MLH1 in oocytes and spermatocytes of the Japanese quail and the zebra finch, we estimated the average amount of recombination in each sex of both species. In each case the number of MLH1 foci is statistically equivalent in males and females and the resulting sex-averaged map lengths are 2800 cM in the Japanese quail and 2275 cM in the zebra finch. In the Japanese quail the MLH1 foci are regularly distributed along the macrobivalents and recombination rates per Mb pair are somewhat lower compared to the chicken. In the zebra finch the MLH1 foci on the macrobivalents are substantially reduced in number relative to the Japanese quail and they show remarkable localization in both sexes. It is proposed that the lack of sex-dependent differences in recombination might be an extended feature among birds and that the different recombination patterns observed here reflect different controls of crossing over in spite of similarities regarding karyotypic asymmetry and DNA content. We discussed possible causes of the differences between birds and mammals, which show sex-dependent recombination differences.
通过对日本鹌鹑和斑胸草雀的卵母细胞和精母细胞中错配修复蛋白MLH1进行免疫定位，我们估算了这两个物种每种性别的平均重组量。在每种情况下，雄性和雌性的MLH1灶数量在统计学上是相等的，由此得出的性别平均图谱长度在日本鹌鹑中为2800厘摩，在斑胸草雀中为2275厘摩。在日本鹌鹑中，MLH1灶沿大双价体规则分布，与鸡相比，每兆碱基对的重组率略低。在斑胸草雀中，大双价体上的MLH1灶数量相对于日本鹌鹑大幅减少，并且在两性中都表现出显著的定位。有人提出，重组中缺乏性别依赖性差异可能是鸟类中的一个普遍特征，并且这里观察到的不同重组模式反映了尽管在核型不对称和DNA含量方面存在相似性，但交叉的控制不同。我们讨论了鸟类和哺乳动物之间差异的可能原因，哺乳动物表现出性别依赖性重组差异。
