A Whole-Chromosome Analysis of Meiotic Recombination in Drosophila melanogaster
A Whole-Chromosome Analysis of Meiotic Recombination in Drosophila melanogaster
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DOI：
10.1534/g3.111.001396
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发表时间：
2012-02-01
影响因子：
2.6
通讯作者：
Hawley, R. Scott
中科院分区：
文献类型：
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作者：
Miller, Danny E.;Takeo, Satomi;Hawley, R. Scott
虽然传统的遗传分析已经描述了果蝇基因组中的交叉模式，但这些分析不能精确地确定交叉的位置。关于非交叉基因转换事件的频率和分布，我们知道的更少。为了评估减数分裂基因转换和交叉事件的具体数量和位置，我们对来自93，538个X染色体单核苷酸和InDel多态性杂合女性的男性后代的基因组进行了测序。从30个F1半合子X染色体的分析中，我们检测到15个交叉和5个非交叉基因转换事件。考虑到多态性沿着染色体臂的不均匀分布，我们估计大多数卵母细胞在每次减数分裂中每对X染色体经历1次交换事件和1.6次基因转换事件。外推到整个基因组将预测每个减数分裂约5个交换事件和8.6个转换事件。平均基因转换区长度估计为476个碱基对，每个减数分裂的核苷酸转换率为0.86 × 10（-5）。这两个值是一致的估计转换频率和道长度从玫瑰色的研究，唯一的基因，基因转换已被广泛研究在果蝇。基序富集分析揭示了GTGGAAA基序，富集附近的交叉，但不是附近的基因转换。低复杂性和频繁出现的这个基序可以部分解释为什么，在哺乳动物系统相反，没有减数分裂交叉热点已被发现在果蝇。
Although traditional genetic assays have characterized the pattern of crossing over across the genome in Drosophila melanogaster, these assays could not precisely define the location of crossovers. Even less is known about the frequency and distribution of noncrossover gene conversion events. To assess the specific number and positions of both meiotic gene conversion and crossover events, we sequenced the genomes of male progeny from females heterozygous for 93,538 X chromosomal single-nucleotide and InDel polymorphisms. From the analysis of the 30 F1 hemizygous X chromosomes, we detected 15 crossover and 5 noncrossover gene conversion events. Taking into account the nonuniform distribution of polymorphism along the chromosome arm, we estimate that most oocytes experience 1 crossover event and 1.6 gene conversion events per X chromosome pair per meiosis. An extrapolation to the entire genome would predict approximately 5 crossover events and 8.6 conversion events per meiosis. Mean gene conversion tract lengths were estimated to be 476 base pairs, yielding a per nucleotide conversion rate of 0.86 x 10(-5) per meiosis. Both of these values are consistent with estimates of conversion frequency and tract length obtained from studies of rosy, the only gene for which gene conversion has been studied extensively in Drosophila. Motif-enrichment analysis revealed a GTGGAAA motif that was enriched near crossovers but not near gene conversions. The low-complexity and frequent occurrence of this motif may in part explain why, in contrast to mammalian systems, no meiotic crossover hotspots have been found in Drosophila.