| Summary: | 碩士 === 國立臺灣大學 === 生化科技學系 === 107 === The nematode-trapping fungus Arthrobotrys oligospora can sense the presence of nematodes. When A. oligospora is exposed to C. elegans, trap morphogenesis is induced. Previous studies showed that ascarosides, a group of conserved nematode pheromones, are sufficient to induce trap morphogenesis in A. oligospora. However, the C. elegans daf-22 mutant which is defective in the production of most ascarosides, is still capable of triggering trap morphogenesis, suggesting that additional cues from the nematodes can be recognized. To identify the potential non-ascaroside factors from C. elegans that trigger trap morphogenesis, we used ethyl methanesulfonate to mutagenize the daf-22 mutant and screened for mutants that exhibited decreased trap induction ability in A. oligospora. Approximately 27,000 F2 mutagenized nematodes were isolated, and 16,000 of which werescreened for their ability to induce traps. Three mutants that induced fewer traps than daf-22 were identified from genetic screens. We used genetic mapping and whole-genome sequencing to identify the mutations that caused decreased trap induction phenotype in the mutant that exhibited the strongest phenotype and identified loss-of-function mutations in cwp-5 and npa-1. Clean deletion mutants of cwp-5 and npa-1 were generated via CRISPR- Cas9 and the mutants were found to induce fewer traps in A. oligospora than the wild-type N2 strain, indicating that cwp-5 and npa-1 play a role in the induction of trap formation.
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