| Summary: | 碩士 === 國立臺灣大學 === 基因體與系統生物學學位學程 === 106 === Sex-ratio (SR) meiotic drives, favoring the transmission of X over Y chromosome, lead to strong female-biased progeny of affected males. SR meiotic drives have been reported in several independent lineages. Yet, the molecular mechanism remains largely unclear. In Drosophila simulans, it has been known that many genes are involved in the Paris SR system, but only HP1D2, a member of the Heterochromatin Protein 1 (HP1) gene family, was identified. HP1D2 possesses a deletion of chromo shadow domain in SR strains and is expressed at lower level in SR relative to wild-type standard (ST) strains. To examine the correlation between the HP1D2 genotype and the SR phenotype, genotyping was performed. The observation of variation of HP1D2 in both ST and SR strains indicates that the genotypes alone cannot predict SR phenotypes. To systematically identify other SR-related genes, the transcriptomic differences of testicular expression between three ST and three SR strains were compared. Among these genes, they are highly enriched in genes associated with multicellular organism reproduction and immune response. The RT-qPCR analysis was then performed to validate 34 genes from the SR candidate genes. Although five genes, namely CG16772, CG15209, Ser7, CG34265, and CG43348, were consistently up-regulated in three SR strains, other differentially expressed genes differed among these strains. The underlying mechanisms and genetic bases of SR strains may be different. Based on the current results, although it is still difficult to distinguish major mechanisms, the killer-target drive or the poison-antidote drive, the killer-target drive is more consistent with the current results. If the target on Y chromosome can be identified, it is possible to elucidate the underlying mechanism of the Paris SR system.
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