Mahtani M M, Willard H F
Department of Genetics, Stanford University School of Medicine, Stanford, California 94305-5120, USA.
Genome Res. 1998 Feb;8(2):100-10. doi: 10.1101/gr.8.2.100.
Classical genetic studies in Drosophila and yeast have shown that chromosome centromeres have a cis-acting ability to repress meiotic exchange in adjacent DNA. To determine whether a similar phenomenon exists at human centromeres, we measured the rate of meiotic recombination across the centromere of the human X chromosome. We have constructed a long-range physical map of centromeric alpha-satellite DNA (DXZ1) by pulsed-field gel analysis, as well as detailed meiotic maps of the pericentromeric region of the X chromosome in the CEPH family panel. By comparing these two maps, we determined that, in the proximal region of the X chromosome, a genetic distance of 0.57 cM exists between markers that span the centromere and are separated by at least the average 3600 kb physical distance mapped across the DXZ1 array. Therefore, the rate of meiotic exchange across the X chromosome centromere is <1 cM/6300 kb (and perhaps as low as 1 cM/17,000 kb on the basis of other physical mapping data), at least eightfold lower than the average rate of female recombination on the X chromosome and one of the lowest rates of exchange yet observed in the human genome.
对果蝇和酵母进行的经典遗传学研究表明，染色体着丝粒具有抑制相邻DNA减数分裂交换的顺式作用能力。为了确定人类着丝粒是否存在类似现象，我们测量了人类X染色体着丝粒区域减数分裂重组的速率。我们通过脉冲场凝胶分析构建了着丝粒α-卫星DNA（DXZ1）的长程物理图谱，以及CEPH家系面板中X染色体着丝粒周围区域的详细减数分裂图谱。通过比较这两张图谱，我们确定，在X染色体的近端区域，跨越着丝粒且被DXZ1阵列上至少平均3600 kb物理距离隔开的标记之间存在0.57 cM的遗传距离。因此，X染色体着丝粒区域减数分裂交换的速率<1 cM/6300 kb（根据其他物理图谱数据，可能低至1 cM/17,000 kb），至少比X染色体上女性重组的平均速率低八倍，是人类基因组中观察到的最低交换速率之一。
