Gene conversions can generate sequence variants in the late chorion multigene families of Bombyx mori.
Gene conversions can generate sequence variants in the late chorion multigene families of Bombyx mori.
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DOI：
10.1093/genetics/120.1.221
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发表时间：
1988-09
期刊：
影响因子：
3.3
通讯作者：
X. Yue;B. Sakaguchi;T. Eickbush
中科院分区：
文献类型：
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作者：
X. Yue;B. Sakaguchi;T. Eickbush
家蚕菌株 703 的 140-kbp 晚期绒毛膜基因座包含 15 个不同方向的基因对，编码高半胱氨酸 (Hc) 蛋壳蛋白。每个基因对的 2 kb 区域（包括 5' 侧翼区域、内含子和外显子）的序列同源性约为 91%。在大多数基因 3' 端的几百个碱基对内，同源性迅速消失。在这里，我们展示了来自家蚕不同种族的 Hc 基因的核苷酸序列和基因组印迹比较结果。比较两个不同种族中相同基因对的核苷酸序列表明，大多数核苷酸差异发生在簇或斑块中，并且对应于该基因座中其他 Hc 基因中存在的序列。基因对高度保守区域 (2.3/100 bp) 中积累的核苷酸差异数量（其中大部分归因于拼凑交换）显着高于保守性较差的 3' 侧翼区域 (0.6/100 bp) 中的差异数量，这主要是由于新突变。这些数据与基因转换过程一致，该过程在短期内会产生新的序列变体组合，但从长远来看会导致协同进化。对家蚕不同地理小种的基因组印迹分析表明，Hc 基因对的数量（14-19 个基因对）存在差异，表明该基因座中也发生了不平等的交换。
The 140-kbp late chorion locus of Bombyx mori strain 703 contains 15 divergently oriented gene pairs encoding the high cysteine (Hc) eggshell proteins. Sequence homology is approximately 91% for the 2-kb region of each gene pair, including the 5' flanking region, intron and exons. The homology rapidly disappears within a few hundred basepairs of the 3' end of most genes. Here we present the results of the nucleotide sequence and genomic blot comparison of Hc genes from different races of B. mori. Comparison of the nucleotide sequences of the same gene pair in two different races reveals that most of the nucleotide differences occur in clusters or patches and correspond to sequences present in other Hc genes in the locus. The number of nucleotide differences that have accumulated in the highly conserved regions of the gene pair (2.3/100 bp), most of which are attributable to patchwork exchanges, is significantly higher than the number of differences in the poorly conserved 3' flanking regions (0.6/100 bp), due primarily to new mutations. These data are consistent with a gene conversion process, which in the short-term generates new combinations of sequence variants, but in the long-term results in concerted evolution. Genomic blot analyses of different geographical races of B. mori reveal that there is variation in the number of Hc gene pairs (14-19 gene pairs), indicating that unequal crossovers also occur in the locus.