Collet C, Nielsen K M, Russell R J, Karl M, Oakeshott J G, Richmond R C
Department of Biology, Indiana University, Bloomington 47405.
Mol Biol Evol. 1990 Jan;7(1):9-28. doi: 10.1093/oxfordjournals.molbev.a040582.
Genomic clones containing sequences homologous to an esterase 6 (Est-6) cDNA clone were isolated from a library of Drosophila melanogaster DNA. Comparison of the genomic and cDNA sequences revealed that the Est-6 gene comprises two exons, one of 1,387 bp and one of 248 bp, separated by a short intron of 51 bp. Further sequencing revealed the presence of a tandem duplication of the Est-6 gene (denoted Est-P) which also has an exon of 1,387 bp and an exon of 248 bp, separated by a short intron of 56 bp. The two genes show similarities of 64% and 60% at the DNA and protein levels, respectively. The coding regions of the genes are 197 bases apart, and presumptive 5' regulatory sequences of Est-P overlap at least the 3' noncoding region of Est-6. Transcripts homologous to Est-P were detected in late larvae and adults of each sex, whereas Est-6 transcripts are present in all life stages but are predominant in adult males. This suggests different physiological functions for the products of the two genes. Southern and Northern blot hybridization analyses of the 20-kb region surrounding the Est-6/Est-P duplication failed to detect any other duplicated esterase genes, although this region is actively transcribed.
从黑腹果蝇DNA文库中分离出了含有与酯酶6（Est-6）cDNA克隆序列同源的基因组克隆。基因组序列与cDNA序列的比较显示，Est-6基因由两个外显子组成，一个为1387 bp，另一个为248 bp，中间被一个51 bp的短内含子隔开。进一步测序发现存在Est-6基因的串联重复（称为Est-P），它也有一个1387 bp的外显子和一个248 bp的外显子，中间被一个56 bp的短内含子隔开。这两个基因在DNA和蛋白质水平上的相似性分别为64%和60%。这两个基因的编码区相距197个碱基，Est-P的推定5'调控序列至少与Est-6的3'非编码区重叠。在各性别的晚期幼虫和成虫中检测到了与Est-P同源的转录本，而Est-6转录本在所有生命阶段都存在，但在成年雄性中占主导地位。这表明这两个基因的产物具有不同的生理功能。对Est-6/Est-P重复序列周围20 kb区域的Southern和Northern印迹杂交分析未能检测到任何其他重复的酯酶基因，尽管该区域正在活跃转录。
