| Summary: | 碩士 === 國立臺灣大學 === 動物學研究所 === 97 === Genes that contribute to the reproductive isolation between species are known as “speciation genes’. Odysseus (OdsH) is a hybrid male sterility gene between Drosophila mauritiana and D. simulans. According to sequence analysis, OdsH duplicated from unc-4 recently in the Drosophila genome preserving the intron exon structure and the paired-like homeodomain. Among D. melaongaster subgroup, the homeodomain of OdsH in D. mauritiana, and D. simulans evolved rapidly. Previous studies showed that OdsH is highly expressed in the testes, and the function of OdsHmel is to enhance male fertility by accelerating the rate of sperm maturation. Three OdsH alleles from D. mauritiana, D. simulans, and D. melanogaster were ectopically expressed in D. melanogaster with the Gal4/UAS system to uncover the molecular mechanism for the function of OdsH. In germline expression, OdsHmau caused developmental defect in the reproductive organs. Germline expression of OdsHmel in females caused the overlapping of nuclei in the embryos and embryonic lethality. In the eyes, all three alleles caused critical defect in the development resulting in small-eye phenotype. Results from embryos and eye discs indicate that cell cycle was perturbed at the mitotic phase with the expression of OdsHmel. Therefore, the molecular mechanism of OdsH appears to play a role in the M phase of cell cycle regulation. Combined with the recent data in the cell culture indicating that OdsH can bind to pericentric satellite DNAs, the mechanism for OdsH to cause hybrid male sterility between D. mauritiana and D. simulans supports the centromere- drive model.
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