| Summary: | 碩士 === 國立陽明大學 === 寄生蟲學研究所 === 90 === In mammals, nitric oxide (NO) is an important signaling molecule involved in regulation of diverse physiological processes, such as inflammation, apoptosis, and neural function. The concomitant release of NO is catalyzed by NO synthase (NOS) through the conversion of L-arginine to L-citrulline. In this study, an Aedes aegypti NOS (AaNOS) cDNA fragment was isolated from bacterial challenged mosquitoes. It contains 3,405 bp of nucleotides, encoding 1,108 amino acids. Moreover, six isoforms of AaNOS cDNA were identified and sequenced using rapid amplification cDNA ends-polymerase chain reaction (RACE -PCR). All cDNAs have high homology with published NOS, and a major AaNOS cDNA bears an open reading frame containing heme, calmodulin, FMN, FAD, NADPH binding domains. The major transcript of AaNOS is about 3 kb and it was induced post-bacterial and post-microfilarial inoculations using quantitative PCR. Interestingly, the levels of AaNOS mRNA and protein in the midgut and ovaries are dramatically enhanced after bacterial challenge detected with quantitative PCR and diaphorase staining, respectively. Two to three copies of AaNOS genes were identified in mosquitoes. The presence of six distinct AaNOS transcripts indicates that alternative splicing may contribute to the transcriptional complexity, and might implicate a novel regulatory function for the family of proteins encoded by AaNOS genes.
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