中文摘要：

【目的】用大肠杆菌Escherichia coli和黑腹果蝇Drosophila melanogaster分别作为微生物和宿主模型,研究微生物对宿主产卵行为的影响,并探讨大肠杆菌对果蝇存活率的影响。【方法】本研究首先利用野生型果蝇在双选择食物装置分别检测果蝇对大肠杆菌发酵食物的产卵偏嗜性和位置效应;利用大肠杆菌细胞和上清液解析诱导这种行为的原因;利用视觉、味觉和嗅觉突变体果蝇检测作用的感觉系统;通过蛹和成虫存活率检验果蝇对大肠杆菌发酵食物的产卵选择后果。【结果】黑腹果蝇产卵对大肠杆菌发酵的食物具有极显著趋避行为,产卵指数为-0.89。黑腹果蝇产卵对大肠杆菌代谢产物的产卵指数为-0.52,对大肠杆菌菌体的产卵指数为0.02。Orco2突变体果蝇产卵对大肠杆菌发酵的食物趋避行为严重受损,对应的产卵指数为-0.25。大肠杆菌在食物上生长,黑腹果蝇后代的存活率不足5%,而划破食物表面可以显著地降低大肠杆菌引起的黑腹果蝇死亡,将其存活率恢复到正常水平。【结论】大肠杆菌会改变黑腹果蝇产卵行为,使黑腹果蝇避开在其发酵食物上产卵;大肠杆菌代谢产物引起黑腹果蝇产卵的趋避性,果蝇主要通过嗅觉并联合其他感觉系统感知大肠杆菌代谢产物;黑腹果蝇对大肠杆菌产卵趋避行为可提高后代存活率,因为大肠杆菌形成一层菌膜,会引起果蝇缺氧死亡。

英文摘要：

【Aim 】 This study aims to investigate the effects of the microbe Escherichia coli on the oviposition preference and survival rate of Drosophila melanogaster. 【Methods】The 2-choice apparatus was used to examine the oviposition and position preference of wild-type D. melanogaster,and bacterial cells and supernatants were utilized to explore the reason for this behavior. D. melanogaster mutants of visual,gustatory and olfactory systems were applied to screen the corresponding sensing to E. coli,and the survival rates of pupae and adults of D. melanogaster were assessed to evaluate the potential effects of E. coli on oviposition selection. 【Results】The female adults of D. melanogaster dramatically avoided to lay eggs on the fly diet fermented by E. coli,with an oviposition index of-0. 89. The female adults avoided to oviposit on the supernatant of E. coli mixture,with an oviposition index of-0. 52,but did not avoid to oviposit on the bacterial cells,with an oviposition index of 0. 02. The Orco^2 mutant was deficient in oviposition repellency to E. coli-associated diet with an oviposition index of-0. 25. E. coli decreased the survival rate of D. melanogaster progeny, with less than 5% individuals surviving, and thescarification on food surface rescued the survival rate of pupae and adults of D. melanogaster.【Conclusion】 Female adults of D. melanogaster select the E. coli fermented food as the favored oviposition site. The oviposition preference of flies stems from the metabolites rather than E. coli cells.The olfactory system is required for D. melanogaster to distinguish the favored oviposition site. The oviposition repellence to E. coli consequently increases the survival and adaption of their offspring,because E. coli forms the aquatic layer on food surface and deprives larvae of oxygen.