a molecular analysis of mutations at the complex dumpy locus in drosophila melanogaster一个突变的分子分析复杂的矮胖的轨迹在黑腹果蝇.pdfVIP

A Molecular Analysis of Mutations at the Complex dumpy Locus in Drosophila melanogaster 1 1 2 1 1 Amber Carmon , Michael J. Guertin , Olga Grushko , Brad Marshall , Ross MacIntyre * 1 Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York, United States of America, 2 Life Sciences Institute, University of Michigan, Ann Arbor, Michigan, United States of America Abstract The Drosophila dumpy gene consists of seventy eight coding exons and encodes a huge extracellular matrix protein containing large numbers of epidermal growth factor-like (EGF) modules and a novel module called dumpy (DPY). A molecular analysis of forty five mutations in the dumpy gene of Drosophila melanogaster was carried out. Mutations in this gene affect three phenotypes: wing shape, thoracic cuticular defects, and lethality. Most of the mutations were chemically induced in a single dumpy allele and were analyzed using a nuclease that cleaves single base pair mismatches in reannealed duplexes followed by dHPLC. Additionally, several spontaneous mutations were analyzed. Virtually all of the chemically induced mutations, except for several in a single exon, either generate nonsense codons or lesions that result in downstream stop codons in the reading frame. The remaining chemically induced mutations remove splice sites in the nascent dumpy message. We propose that the vast majority of nonsense mutations that affect all three basic dumpy phenotypes are in constitutive exons, whereas nonsense mutants that remove only one or two of the basic functions are in alternatively spliced exons. Evolutionary comparisons of the dumpy gene