Cytological Mechanism of Autophagosome Biogenesis During Cell Autophagic Apoptosis in Rice and Insect Cell

【Objective】An experiment was carried out to study the change of membrane organelles during cell autophagy and the relationship of membrane organelles and autophagosome biogenesis at cellular level.【Method】 Recent studies have shown that cell apoptosis in the Japonica/Javanica hybrid rice F1 is caused by gene interactions and apoptotic Sf9 cell can be induced by natural chemicals such as azadirachtin,camptothecin,and matrine.In this study,autophagosome biogenesis were observed in the cells of hybrid rice F1and Sf6 cells treated by chemicals using transmission electron microscope and fluorescence microscopy.【Result】 The results showed that pollen mother cells of hybrid rice F1 degenerated partly at different stages during microsporogenesis.The morphology of mitochondria in some cells expanded into dumbbell or pipe-like line shape which eventually developed into a double-membrane organelle.Whereas,in tapetal cells the endoplasmic reticulum swelled and expanded into a double-membrane autophagosomes,enwrapping a portion of cytoplasm and other organelles such as mitochondrias and peroxisomes,suggesting the occurrence of autophagic apoptosis.The mitochondrias in apoptotic cells treated by camptothecin and matrine elongated and curved into dumbbell or pipe-like line shape which eventually developed into double-membrane autophagosomes,enwrapping other organelles.Nuclei in apoptotic cells treated by azadirachtin or camptothecin formed the double-membrane autophagosomes by the ways of pagination and sprouting.【Conclusion】In conclusion,the membrane organelles including endoplasmic reticulum,mitochondrias and nuclei were all the direct origin of autophagosome membrane during the autophagic apoptosis in plant and animal cells.However,the degree and manner contributed by the three membrane organelles during the formation of autophagosome were dependent on the species,cell categories and the factors inducing apoptosis.