Analysis of oogenesis defects inDyromutant ofDrosophila melanogaster

Abstract

AbstractDyromutant is female sterile, and oogenesis is aborted during stage8-9 of oogenesis. We investigated detail of the oogenesis defect ofDyromutant. At first, we confirmed loss of Dyro caused female sterility by genetic rescue experiment. Then, we performed genetic mosaic analysis and found Dyro expression in germ cell is important for oogenesis. InDyromutant, inhibition of programmed cell death suppressed cell death of germ cells during oogenesis but failed to rescue fertility. It indicates that abortion of oogenesis is not because of mis-regulation of cell death signal but there is oogenesis defect which activates Caspase signaling pathway. Then, we observedDyromutant and looking for defects which may trigger cell death of germ cells inDyromutant. We found oogenesis abortion timing is similar to yolk protein mutant but different from amino acid starvation. It suggests that nutrient signal defect does not triggers cell death inDyromutant. We carefully observed the defect ofDyromutant ovaries and found abnormal morphology of nucleolus and chromosome in nurse cells. It seems chromosome inDyromutant is thick and nucleolus is limited in small space between thick chromosomes inDyromutant nurse cells. Other defect we found is aggregated protein accumulation in germ cells. These data suggest thatDyrohas important role in mid-oogenesis stage germ cell and loss of Dyro causes defect in nuclear of nurse cells which may leads to abortion of oogenesis.