Homologous chromosome pairing in Drosophila melanogaster proceeds through multiple independent initiations.
Homologous chromosome pairing in Drosophila melanogaster proceeds through multiple independent initiations.
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DOI：
10.1083/jcb.141.1.5
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发表时间：
1998-04-06
期刊：
影响因子：
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通讯作者：
Sedat JW
中科院分区：
文献类型：
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作者：
Fung JC;Marshall WF;Dernburg A;Agard DA;Sedat JW
同源染色体配对的动力学目前尚不清楚。在这里，我们使用荧光原位杂交结合三维光学显微镜显示，同源配对的果蝇体细胞染色体臂2L发生独立的启动配对在离散的位点，而不是由一个进行性拉链的网站沿着染色体长度。通过评估染色体臂2L上的11个位点在果蝇胚胎发育过程中的几个时间点的配对频率，我们发现，所有11个位点在果蝇发育的早期配对，在13小时内蛋沉积。为了阐明这种配对是否发生定向或无向运动，我们分析了组蛋白位点在核周期14配对动力学。通过测量细胞核长度的变化，并将这些变化与第14周期的时间进程相关联，我们能够表达配对频率和同源基因座之间的距离作为时间的函数。比较实验确定的动态配对的模拟基于先前提出的模型的配对运动，我们表明，所观察到的配对动力学是最一致的约束随机游走模型，并不符合定向运动模型。因此，我们的结论是，简单的随机接触，通过扩散可能足以允许配对的同源位点。
The dynamics by which homologous chromosomes pair is currently unknown. Here, we use fluorescence in situ hybridization in combination with three-dimensional optical microscopy to show that homologous pairing of the somatic chromosome arm 2L in Drosophila occurs by independent initiation of pairing at discrete loci rather than by a processive zippering of sites along the length of chromosome. By evaluating the pairing frequencies of 11 loci on chromosome arm 2L over several timepoints during Drosophila embryonic development, we show that all 11 loci are paired very early in Drosophila development, within 13 h after egg deposition. To elucidate whether such pairing occurs by directed or undirected motion, we analyzed the pairing kinetics of histone loci during nuclear cycle 14. By measuring changes of nuclear length and correlating these changes with progression of time during cycle 14, we were able to express the pairing frequency and distance between homologous loci as a function of time. Comparing the experimentally determined dynamics of pairing to simulations based on previously proposed models of pairing motion, we show that the observed pairing kinetics are most consistent with a constrained random walk model and not consistent with a directed motion model. Thus, we conclude that simple random contacts through diffusion could suffice to allow pairing of homologous sites.