| Summary: | 碩士 === 國立臺灣大學 === 生命科學系 === 102 === Drosophila sechellia is the only species feeding on the Noni fruit, Morinda citrifola, which is toxic to the other Drosophila species. Previous genetic mapping indicated that a 169 kb D. sechellia genomic region spanning 18 genes on the third chromosome is responsible for resistance to the major toxic component, octanoic acid, of Noni fruit. To identify the candidate genes affecting octanoic acid resistance, I examined the expression patterns of 18 candidate genes in D. sechellia and two sibling species, D. melanogaster and D. simulans, by reverse transcription PCR. Because the octanoic acid resistance is shown in both sexes of D. sechellia, five genes were excluded to associate with the resistance. Over expression of three D. sechellia odorant binding protein (obp) genes namely, obp83cd, obp83e, and obp83g, in D. simulans by heat-shock Gal4 transgenes, does not increase the octanoic acid resistance. Moreover, I enhanced and reduced Neuropeptide F receptor (NPFR1) expression in D. melanogaster, respectively, and found that the NPFR1 overexpressed flies showed less resistance to octanoic acid than the wild type flies. The results suggest that octanoic acid resistance in D. sechellia might be contributed either by multiple genes or by the other candidate genes that were not investigated in this study.
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