Retrotransposable elements on the W chromosome of the silkworm, Bombyx mori
Retrotransposable elements on the W chromosome of the silkworm, Bombyx mori
复制标题
DOI：
10.1159/000084946
复制
发表时间：
2005-01-01
影响因子：
1.7
通讯作者：
Shimada, T
中科院分区：
文献类型：
--
作者：
Abe, H;Mita, K;Shimada, T
家蚕的性染色体命名为ZW（XY）（雌性）和ZZ（XX）（雄性）。B的W染色体。桑不与Z染色体和常染色体重组，也没有形态性状基因被定位到W染色体上。此外，无论常染色体或Z染色体的数量如何，女性都是由单个W染色体的存在决定的。为了了解W染色体的这些有趣的特征，有必要在分子生物学水平上分析W染色体。最初，分离特异性的W染色体的DNA序列作为随机扩增多态性DNA（RAPD）标记，我们比较了男性和女性之间的基因组DNA的PCR与任意的10聚体引物。到目前为止，我们已经确定了12个W特异的RAPD标记，除了一个RAPD标记外，所有这些W特异的RAPD标记的推导的氨基酸序列与以前报道的各种生物的反转录转座因子的氨基酸序列相似。构建了B. mori中获得了两个λ噬菌体克隆，一个含有W-KabukiRAPD序列，另一个含有W-Samurai RAPD序列，并发现这些DNA序列包含许多逆转录转座因子的嵌套结构。为了进一步分析W染色体，我们从三个BAC文库中获得了14个W特异性细菌人工染色体（BAC）克隆，并对这些克隆进行鸟枪测序。由于存在许多逆转录转座因子，所产生的序列组装不产生单个连续序列。因此，我们将PCR与鸟枪测序相结合。通过这些分析，我们发现许多长末端重复序列（LTR）和非LTR的反转录转座子、反转录子、DNA转座子及其衍生物，已经作为层积累在W染色体上。这些结果有力地表明，反转录转座因子是W染色体的主要结构成分。版权所有（c）2005 S. Karger AG，巴塞尔。
The sex chromosomes of the silkworm, Bombyx mori, are designated ZW(XY) for females and ZZ(XX) for males. The W chromosome of B. mori does not recombine with the Z chromosome and autosomes and no genes for morphological characters have been mapped to the W chromosome as yet. Furthermore, femaleness is determined by the presence of a single W chromosome, regardless of the number of autosomes or Z chromosomes. To understand these interesting features of the W chromosome, it is necessary to analyze the W chromosome at the molecular biology level. Initially to isolate DNA sequences specific for the W chromosome as randomly amplified polymorphic DNA (RAPD) markers, we compared the genomic DNAs between males and females by PCR with arbitrary 10-mer primers. To the present, we have identified 12 W-specific RAPD markers, and with the exception of one RAPD marker, all of the deduced amino acid sequences of these W-specific RAPD markers show similarity to previously reported amino acid sequences of retrotransposable elements from various organisms. After constructing a genomic DNA lambda phage library of B. mori we obtained two lambda phage clones, one containing the W-Kabuki RAPD sequence and one containing the W-Samurai RAPD sequence and found that these DNA sequences comprised nested structures of many retrotransposable elements. To further analyze the W chromosome, we obtained 14 W-specific bacterial artificial chromosome (BAC) clones from three BAC libraries and subjected these clones to shotgun sequencing. The resulting assembly of sequences did not produce a single contiguous sequence due to the presence of many retrotransposable elements. Therefore, we coupled PCR with shotgun sequencing. Through these analyses, we found that many long terminal repeat (LTR) and non-LTR retrotransposons, retroposons, DNA transposons and their derivatives, have accumulated on the W chromosome as strata. These results strongly indicate that retrotransposable elements are the main structural component of the W chromosome. Copyright (c) 2005 S. Karger AG, Basel.