Taft A S, Chen C C, Li J, Christensen B M
Department of Animal Health and Biomedical Sciences, University of Wisconsin-Madison, 1656 Linden Drive, Madison, WI 53706, USA.
Insect Mol Biol. 2001 Feb;10(1):97-103. doi: 10.1046/j.1365-2583.2001.00242.x.
The biosynthesis of melanotic materials is an important process in the life of a mosquito. Melanin production is critical for many diverse processes such as egg chorion tanning, cuticular sclerotization, and melanotic encapsulation of metazoan parasites. Prophenoloxidase plays a critical role in this biochemical cascade. Two cDNAs, one full length and one partial clone, and two genomic clones encoding prophenoloxidase (pro-PO) were isolated from the yellow fever mosquito, Aedes aegypti. The full-length cDNA, pAaProPO1, is 2286 bp long with a 2055 bp open reading frame encoding a 685 amino acid protein that shares 89% identity with Armigeres subalbatus pro-PO. It contains two putative copper binding domains (amino acids 197-243 and 346-423) that are homologous to other insect pro-POs. AaProPO1 messenger RNA (mRNA) was detected by reverse transcription polymerase chain reaction (RT-PCR) only from third-stage larvae and not in adult mosquitoes after blood feeding, during the melanotic encapsulation of Dirofilaria immitis microfilariae or following exposure to bacteria. A 750 bp fragment of the second cDNA (pAaProPO2) was cloned using RT-PCR from mRNA obtained from 14-day postovipostional eggs. AaProPO2 mRNA was not found in any other life stages, and may be in low abundance or transiently expressed. AaProPO2 and AaProPO1 each contain three introns that are 60, 68 and 58 bp and 61, 69 and 59 bp long, respectively, and the intron sequences of these two genes are not similar.
黑色素物质的生物合成是蚊子生命中的一个重要过程。黑色素的产生对于许多不同的过程至关重要，如卵壳鞣化、表皮硬化以及后生动物寄生虫的黑色素包囊化。前酚氧化酶在这个生化级联反应中起着关键作用。从黄热病蚊子埃及伊蚊中分离出了两个cDNA（一个全长和一个部分克隆）以及两个编码前酚氧化酶（pro-PO）的基因组克隆。全长cDNA pAaProPO1长2286 bp，有一个2055 bp的开放阅读框，编码一个685个氨基酸的蛋白质，与骚扰阿蚊的pro-PO有89%的同一性。它包含两个假定的铜结合结构域（氨基酸197 - 243和346 - 423），与其他昆虫的pro-PO同源。仅在三期幼虫中通过逆转录聚合酶链反应（RT-PCR）检测到AaProPO1信使核糖核酸（mRNA），而在成年蚊子吸血后、在犬恶丝虫微丝蚴的黑色素包囊化过程中或接触细菌后均未检测到。使用RT-PCR从产卵后14天的卵中获得的mRNA克隆了第二个cDNA（pAaProPO2）的一个750 bp片段。在任何其他生命阶段均未发现AaProPO2 mRNA，其可能丰度较低或瞬时表达。AaProPO2和AaProPO1各自包含三个内含子，长度分别为60、68和58 bp以及61、69和59 bp，并且这两个基因的内含子序列不相似。
