Whyard S, Tittiger C, Walker V K
Department of Biology and Insect Biotech Canada, Queen's University, Kingston, Ontario.
Insect Biochem Mol Biol. 1994 Dec;24(10):1017-24. doi: 10.1016/0965-1748(94)90139-2.
The enzyme triosephosphate isomerase (TPI) was purified to homogeneity from the mosquito Culex tarsalis. Anti-C. tarsalis TPI antibodies cross-reacted with TPIs from other organisms but bands on western blots were most intense with proteins from closely related Dipterans. Using a degenerate primer corresponding to the amino-terminal sequence of the protein in a polymerase chain reaction (PCR), a cDNA corresponding to the TPI gene (Tpi) was isolated and sequenced. Subsequently, a genomic sequence including 305 bp to the 5'-end of the coding sequence was obtained. Comparison of C. tarsalis Tpi to that of Drosophila melanogaster revealed that although the two genes had little similarity in the intron and 5' flanking sequences, they were highly similar (73% identity) in their coding sequence. The rate of synonymous substitution in insect genes may be slower than that of vertebrates, but the nonsynonymous substitution rate, and hence the rate of TPI evolution, appears to be faster in insects than in vertebrates.
磷酸丙糖异构酶（TPI）从致倦库蚊中纯化至同质。抗致倦库蚊TPI抗体与其他生物体的TPI发生交叉反应，但在蛋白质印迹上，与亲缘关系较近的双翅目动物的蛋白质条带最为明显。在聚合酶链反应（PCR）中使用与该蛋白质氨基末端序列对应的简并引物，分离并测序了与TPI基因（Tpi）对应的cDNA。随后，获得了包括编码序列5'端305 bp的基因组序列。将致倦库蚊的Tpi与黑腹果蝇的Tpi进行比较，结果显示，尽管这两个基因在内含子和5'侧翼序列上相似度较低，但它们的编码序列高度相似（同一性为73%）。昆虫基因的同义替换率可能比脊椎动物慢，但非同义替换率以及TPI的进化速率在昆虫中似乎比在脊椎动物中更快。
