Ruhr-Universität Bochum, Lehrstuhl für Biochemie, D-4630 Bochum, FRG.
EMBO J. 1984 Feb;3(2):289-95. doi: 10.1002/j.1460-2075.1984.tb01798.x.
The puffing cycle of salivary gland chromosomes of Drosophila larvae, which initiates the developmental path to pupariation, is induced by ecdysteroid hormone. Its action leads to prominent puffs at loci 2B5, 74EF and 75B. Fragments of the 74EF puff of the D. melanogaster 3L chromosome were microdissected from salivary gland squashes. EcoRI-digested DNA of these fragments was cloned into lambda phage. Clones were screened with puff stage-specific cDNA probes. Thirteen out of 650 clones hybridized preferentially with puff stage 4-specific cDNA. The prominent early puffs at 74EF and 75B are most active between puff stage 4 and 6. Therefore, one of the 13 lambda phages was chosen for further analysis. It was used to isolate 24 kb of Drosophila DNA from genomic libraries. The DNA hybridized in situ to locus 74F. The 74F DNA coded for a transcript, which was made in salivary glands, but not in fat body of third instar larvae. It accumulated in K(C) cells in response to ecdysteroid treatment. The polyadenylated transcript size was 2.7 kb as judged by Nothern blot analysis. The transcription start site of the 74F gene has been mapped. Sequences upstream of the transcription site contain several sequence elements common to other eucaryotic genes, including potential Z-DNA forming sequences. Also, there is sequence homology to upstream sequences, which have been involved in the regulation of transcription of the salivary gland glue protein 4 gene.
果蝇幼虫唾液腺染色体的膨突循环启动了蛹化的发育途径，它是由蜕皮激素诱导的。其作用导致 2B5、74EF 和 75B 等基因座位出现明显的膨突。从果蝇 3L 染色体的 74EF 膨突中分离出唾液腺匀浆中的片段。用 EcoRI 消化这些片段的 DNA，将其克隆到 λ噬菌体中。用膨突阶段特异性 cDNA 探针筛选克隆。在 650 个克隆中，有 13 个与膨突阶段 4 特异性 cDNA 优先杂交。74EF 和 75B 的早期明显膨突在膨突阶段 4 和 6 之间最为活跃。因此，选择其中的一个 λ噬菌体进行进一步分析。它被用于从基因组文库中分离出 24kb 的果蝇 DNA。该 DNA 在原位杂交中与 74F 基因座杂交。74F DNA 编码一种在唾液腺中产生的转录本，但不在三龄幼虫的脂肪体中产生。它在响应蜕皮激素处理时在 K(C)细胞中积累。多聚腺苷酸化转录本的大小为 2.7kb，这是通过 Northern blot 分析判断的。74F 基因的转录起始位点已被定位。转录起始位点上游的序列包含几个真核基因常见的序列元件，包括潜在的 Z-DNA 形成序列。此外，与参与调控唾液腺粘蛋白 4 基因转录的上游序列也有同源性。
