Investigation the role of autophagy in midgut stem cells of silkworm Bombyx mori, during larval-pupal metamorphosis

INVESTIGATION THE ROLE OF AUTOPHAGY IN MIDGUT STEM CELLS OF SILKWORM BOMBYX MORI, DURING LARVAL-PUPAL METAMORPHOSIS GÜNAY, Büşra MSc in Biology Supervisor: Assoc. Prof. Dr. Ebru GÖNCÜ February 2018 Midgut of silkworm Bombyx mori which passes complete metamorphosis, go into remodelling timing during larval-pupal metamorphosis. Mature cells of larval midgut epithelium is completely dejenerated with apoptosis and autophagy mechanisms. Larval stem cells lead to formation of pupal epithelium passing growing, proliferating and differentiation. Autophagy is intracellular recycling mechanism which leads in cases of false folding, being old, disused, damaged intracellular macro molecules and organels broken down and recovered of integral parts. It is thought that autophagy which provides self-renewal, proliferating and differentiation of stem cells, is a critical mechanism. It is supposed that, in these processes, autophagy is the most important mechanism in stem cells. This provides food and energy source during remodelling into cells. İn this study, autophagy mechanism's role was searched in stem cells which is formated pupal midgut in Bombyx mori. With this aim, it was realized in different days of 5. larval stage and different doses using chloroquine via injection. After these practices, it was performed morphological and biochemical analysis. Being inhibition of autophagy mechanism blocked larval-pupal molting and it was showed that causing death of Bombyx mori. Also, when Autophagy mechanism was blocked by chloroquine, proliferation ratio decreased in stem cells and seemed stopping of differentiation. It was obtained powerfull evidences of autophagy, stem cells in beginning of both proliferation and differentiation timing, may have important roles. Due to similarity of mammals and insect stem cells, it will contribute, obtained results not only in insect physiology studies but also not looking out for difference of species different stem cells'biologies understanding. Key words: Bombyx mori, midgut, stem cell, autophagy