Partial deletions of the W chromosome due to reciprocal translocation in the silkworm Bombyx mori
Partial deletions of the W chromosome due to reciprocal translocation in the silkworm Bombyx mori
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DOI：
10.1111/j.1365-2583.2005.00565.x
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发表时间：
2005-08-01
影响因子：
2.6
通讯作者：
Shimada, T
中科院分区：
文献类型：
--
作者：
Abe, H;Seki, M;Shimada, T
在蚕（Bombyx mori）（雌性，ZW；雄性，ZZ）中，雌性由单个 W 染色体的存在决定，与常染色体或 Z 染色体的数量无关。除了假定的女性决定基因（Fem）之外，W 染色体缺乏功能基因。然而，有些品系中含有常染色体标记的染色体片段已被易位到W上。在本研究中，我们在分子水平上分析了Zebra-W品系（T(W;3)Ze染色体）和黑蛋-W品系（T(W;10)+(w-2)染色体）的W染色体区域。最初，除了三个已经建立的 W 特异性 RAPD 标记（W-Kabuki、W-Samurai 和 W-Kamikaze）之外，我们还开展了一个鉴定 W 特异性 RAPD 标记的项目。经过对3648个任意10聚体引物的筛选，我们获得了9个W特异性RAPD标记序列（W-Bonsai、W-Mikan、W-Musashi、W-Rikishi、W-Sakura、W-Sasuke、W-Yukemuri-L、W-Yukemuri-S和BMC1-Kabuki），几乎所有序列都包含反转录转座子的边界区域，即部分 嵌套的逆转录转座子。我们证实，日本饲养的 25 种蚕品系的正常 W 染色体中存在 12 个 W 特异性 RAPD 标记中的 11 个。这些结果表明日本菌株的W染色体类型几乎相同。 Zebra-W 品系（T(W;3)Ze 染色体）缺乏 W-Samurai 和 W-Mikan RAPD 标记，Black-egg-W 品系（T(W;10)+(w-2) 染色体）缺乏 W-Mikan RAPD 标记。这些结果强烈表明，由于 W 染色体和常染色体之间的相互易位，含有 W-Samurai 和 W-Mikan RAPD 标记或 W-Mikan RAPD 标记的区域分别在 T(W;3)Ze 和 T(W;10)+(w-2) 染色体中被删除。这种删除显然不影响 Fem 的表达；因此，W 染色体的这个删除区域不包含假定的 Fem 基因。
In the silkworm, Bombyx mori (female, ZW; male, ZZ), femaleness is determined by the presence of a single W chromosome, irrespective of the number of autosomes or Z chromosomes. The W chromosome is devoid of functional genes, except the putative female-determining gene (Fem). However, there are strains in which chromosomal fragments containing autosomal markers have been translocated on to W. In this study, we analysed the W chromosomal regions of the Zebra-W strain (T(W;3)Ze chromosome) and the Black-egg-W strain (T(W;10)+(w-2) chromosome) at the molecular level. Initially, we undertook a project to identify W-specific RAPD markers, in addition to the three already established W-specific RAPD markers (W-Kabuki, W-Samurai and W-Kamikaze). Following the screening of 3648 arbitrary 10-mer primers, we obtained nine W-specific RAPD marker sequences (W-Bonsai, W-Mikan, W-Musashi, W-Rikishi, W-Sakura, W-Sasuke, W-Yukemuri-L, W-Yukemuri-S and BMC1-Kabuki), almost all of which contained the border regions of retrotransposons, namely portions of nested retrotransposons. We confirmed the presence of eleven out of twelve W-specific RAPD markers in the normal W chromosomes of twenty-five silkworm strains maintained in Japan. These results indicate that the W chromosomes of the strains in Japan are almost identical in type. The Zebra-W strain (T(W;3)Ze chromosome) lacked the W-Samurai and W-Mikan RAPD markers and the Black-egg-W strain (T(W;10)+(w-2) chromosome) lacked the W-Mikan RAPD marker. These results strongly indicate that the regions containing the W-Samurai and W-Mikan RAPD markers or the W-Mikan RAPD marker were deleted in the T(W;3)Ze and T(W;10)+(w-2) chromosomes, respectively, due to reciprocal translocation between the W chromosome and the autosome. This deletion apparently does not affect the expression of Fem; therefore, this deleted region of the W chromosome does not contain the putative Fem gene.