Ganguly R, Swanson K D, Ray K, Krishnan R
Department of Zoology, University of Tennessee, Knoxville 37996.
Proc Natl Acad Sci U S A. 1992 Feb 15;89(4):1340-4. doi: 10.1073/pnas.89.4.1340.
In Drosophila miranda, females have two X1 and two evolving X2 chromosomes, and males have one of each of these two X chromosomes and a Y chromosome. In males, the homologue of the X2 chromosome, the neo-Y chromosome, is attached to the Y chromosome and is under the process of degenerative evolution. We have examined a developmentally regulated X2/neo-Y chromosome-linked gene, 549mr, of D. miranda and found that the neo-Y chromosome-linked copy of this gene (549mr-NY) contains an insertional DNA. We discovered that sequences similar to those in the insertional DNA are present in multiple copies in the genome of both sexes of D. miranda but are more abundant in the males. The insertional DNA also identified a 1.1-kilobase BamHI repeat that is present in at least 6-fold excess in the male genome as compared to the female. This BamHI repeat and similar DNA sequences are predominantly concentrated on the evolving neo-Y chromosome, but very few are found on the homologous X2 and other chromosomes. The BamHI repeat also hybridizes with 2.0- and 1.8-kb RNAs and many other RNA species, which together are also approximately 6-fold greater in males. No sequences similar to the BamHI repeat are found in Drosophila melanogaster. Moreover, the BamHI repeat is not homologous to P, copia, or other D. melanogaster transposable elements. This repeat, named the NY element, may be involved in gene disruption and the process of degenerative evolution of the neo-Y chromosome.
在果蝇米兰达中，雌性有两条X1染色体和两条正在进化的X2染色体，而雄性有这两条X染色体各一条以及一条Y染色体。在雄性中，X2染色体的同源染色体，即新Y染色体，附着在Y染色体上，正处于退化进化过程中。我们研究了果蝇米兰达中一个受发育调控的X2/新Y染色体连锁基因549mr，发现该基因的新Y染色体连锁拷贝（549mr-NY）包含一段插入DNA。我们发现，与插入DNA中的序列相似的序列在果蝇米兰达雌雄两性的基因组中都有多个拷贝，但在雄性中更为丰富。插入DNA还鉴定出一个1.1千碱基的BamHI重复序列，与雌性相比，该重复序列在雄性基因组中的含量至少多出6倍。这个BamHI重复序列和类似的DNA序列主要集中在正在进化的新Y染色体上，但在同源的X2染色体和其他染色体上很少发现。BamHI重复序列还与2.0千碱基和1.8千碱基的RNA以及许多其他RNA种类杂交，这些RNA在雄性中的总量也大约多出6倍。在黑腹果蝇中未发现与BamHI重复序列相似的序列。此外，BamHI重复序列与P、copia或其他黑腹果蝇转座元件不同源。这个重复序列，命名为NY元件，可能参与了基因破坏和新Y染色体的退化进化过程。
