Spradling A C, de Cicco D V, Wakimoto B T, Levine J F, Kalfayan L J, Cooley L
EMBO J. 1987 Apr;6(4):1045-53. doi: 10.1002/j.1460-2075.1987.tb04857.x.
Genomic sequences controlling follicle cell-specific amplification of the X-linked Drosophila chorion gene cluster were mapped by P element-mediated transformation. Several DNA fragments containing the s38 gene and flanking sequences induced tissue-specific amplification, although replication levels were subject to position effects. Deletion analysis identified a 467-bp region upstream from the s38 transcription start site that contained sequences essential in cis for amplification. The essential region shared 32 bp of imperfect sequence homology with a previously identified region necessary for third chromosome chorion gene cluster amplification. This homologous segment contained a repetitive motif consisting of perfect and imperfect AATAC repeats; it was localized near the boundary of the essential domain since most, but not all, the repeats could be deleted without eliminating transposon-induced amplification. The repetitive region was not required for developmentally regulated s38 transcription, therefore our results identified at least one element required for amplification but not for chorion gene transcription. The homologous repetitive sequences within the amplification-essential regions may constitute part of the replication origins used to differentially replicate the two chorion domains during oogenesis.
通过P因子介导的转化，对控制X连锁果蝇绒毛膜基因簇卵泡细胞特异性扩增的基因组序列进行了定位。几个包含s38基因及其侧翼序列的DNA片段诱导了组织特异性扩增，尽管复制水平受位置效应影响。缺失分析确定了s38转录起始位点上游467bp的区域，该区域包含顺式作用下扩增所必需的序列。该必需区域与先前鉴定的第三染色体绒毛膜基因簇扩增所需区域有32bp的不完全序列同源性。这个同源片段包含一个由完美和不完美的AATAC重复序列组成的重复基序；它位于必需结构域的边界附近，因为大多数（但不是全部）重复序列可以被删除而不消除转座子诱导的扩增。重复区域对于发育调控的s38转录不是必需的，因此我们的结果确定了至少一个扩增所必需但绒毛膜基因转录不需要的元件。扩增必需区域内的同源重复序列可能构成了在卵子发生过程中用于差异复制两个绒毛膜结构域的复制起点的一部分。
