Brown C J, Aquadro C F, Anderson W W
Department of Genetics, University of Georgia, Athens, 30602.
Genetics. 1990 Sep;126(1):131-8. doi: 10.1093/genetics/126.1.131.
The alpha-Amylase locus in Drosophila pseudoobscura is a multigene family of one, two or three copies on the third chromosome. The nucleotide sequences of the three Amylase genes from a single chromosome of D. pseudoobscura are presented. The three Amylase genes differ at about 0.5% of their nucleotides. Each gene has a putative intron of 71 (Amy1) or 81 (Amy2 and Amy3) bp. In contrast, Drosophila melanogaster Amylase genes do not have an intron. The functional Amy1 gene of D. pseudoobscura differs from the Amy-p1 gene of D. melanogaster at an estimated 13.3% of the 1482 nucleotides in the coding region. The estimated rate of synonymous substitutions is 0.398 +/- 0.043, and the estimated rate of nonsynonymous substitutions is 0.068 +/- 0.008. From the sequence data we infer that Amy2 and Amy3 are more closely related to each other than either is to Amy1. From the pattern of nucleotide substitutions we reason that there is selection against synonymous substitutions within the Amy1 sequence; that there is selection against nonsynonymous substitutions within the Amy2 sequence, or that Amy2 has recently undergone a gene conversion with Amy1; and that Amy3 is nonfunctional and subject to random genetic drift.
拟暗果蝇的α淀粉酶基因座是位于第三条染色体上的一个由一、二或三个拷贝组成的多基因家族。本文给出了来自拟暗果蝇单条染色体的三个淀粉酶基因的核苷酸序列。这三个淀粉酶基因在约0.5%的核苷酸位点上存在差异。每个基因都有一个71bp（Amy1）或81bp（Amy2和Amy3）的推定内含子。相比之下，黑腹果蝇的淀粉酶基因没有内含子。拟暗果蝇的功能性Amy1基因与黑腹果蝇的Amy-p1基因在编码区1482个核苷酸中约13.3%的位点上存在差异。同义替换的估计速率为0.398±0.043，非同义替换的估计速率为0.068±0.008。从序列数据我们推断，Amy2和Amy3彼此之间的关系比它们与Amy1的关系更为密切。从核苷酸替换模式我们推断，Amy1序列内存在针对同义替换的选择；Amy2序列内存在针对非同义替换的选择，或者Amy2最近与Amy1发生了基因转换；并且Amy3无功能，受随机遗传漂变影响。
