An unusual Y chromosome of Drosophila simulans carrying amplified rDNA spacer without rRNA genes.
An unusual Y chromosome of Drosophila simulans carrying amplified rDNA spacer without rRNA genes.
复制标题
模拟果蝇的不寻常 Y 染色体携带扩增的 rDNA 间隔区，但不含 rRNA 基因。
作者：
A. Lohe;P. Roberts
果蝇的 X 和 Y 染色体各含有数百个核糖体 RNA 基因 (rDNA)。非转录间隔区分隔相邻的 rRNA 基因，并包含 240 bp 重复序列的串联拷贝，其中包括 RNA 聚合酶 I 转录的起始位点。我们在此表明，模拟果蝇 (Drosophila simulans)（黑腹果蝇的同胞物种）在其 Y 染色体上包含很少（如果有的话）rRNA 基因，但携带一大块（3,000 kb 或 12,500 个拷贝）240 bp 非转录间隔重复序列。这些重复序列位于拟果蝇 Y 染色体长臂的末端，而它们位于黑腹果蝇 Y 染色体短臂上的 rRNA 基因中。由于 X 染色体上的 rRNA 基因部分缺失，黑腹果蝇纯合雌性的短毛突变使刚毛变短变薄。由于 Y 染色体上存在完整的 rRNA 基因，短毛/Y 型雄性的鬃毛是正常的。特殊的是，在拟毛拟蜥蜴的短毛/Y 雄性中，短鬃毛表型不会恢复正常，而是由于 Y 染色体的存在而增强。我们认为，Y 染色体上的 12,500 个非转录间隔重复序列通过竞争 X 连锁基因座上正常 rDNA 转录水平所必需的蛋白质因子而产生了这种生物效应。
The X and Y chromosomes of Drosophila melanogaster each contain a cluster of several hundred ribosomal RNA genes (rDNA). A nontranscribed spacer region separates adjacent rRNA genes and contains tandem copies of 240 bp repeats that include the initiation site for RNA polymerase I transcription. We show here that Drosophila simulans, a sibling species of D. melanogaster, contains few, if any, rRNA genes on its Y chromosome but carries instead a large block (3,000 kb or 12,500 copies) of 240 bp nontranscribed spacer repeats. The repeats are located at the tip of the long arm of the simulans Y chromosome, in contrast to their location among rRNA genes on the short arm of the Y chromosome of D. melanogaster. The bobbed mutation in homozygous females of D. melanogaster shortens and thins the bristles, owing to a partial deletion of rRNA genes on the X chromosome. The bristles of bobbed/Y males are normal owing to the presence of a full complement of rRNA genes on the Y chromosome. Peculiarly, in bobbed/Y males of D. simulans the short bristle phenotype does not return to normal but is enhanced by the presence of the Y chromosome. We propose that the 12,500 nontranscribed spacer repeats on the Y chromosome are responsible for this biological effect by competition for a protein factor(s) essential for normal levels of rDNA transcription at the X-linked locus.
DOI：
10.1073/pnas.86.6.1944
发表时间：
1989-03-01
影响因子：
11.1
作者：
LYCKEGAARD, EMS;CLARK, AG
通讯作者：
CLARK, AG