Investigation of the effects of starvation stress in the midgut of the silkworm Bombyx mori

Abstract

During their evolution, organisms have developed various mechanisms to adapt to changing nutritional conditions such as mobilization of storage molecules and activation of autophagy. In this study, the mechanism of adaptive responses in the midgut of the silkworm Bombyx mori L., 1758 (Lepidoptera: Bombycidae) larvae, which were starved for different days, was investigated. The study was carried out at the Insect Physiology Research Laboratory and Silkworm Culture Laboratory at Ege University between 2018 and 2020. For this purpose, the histological structure of the midgut was examined using hematoxylin&eosin staining and its protein, sugar, glycogen, and lipid contents were determined. As autophagy markers, lysosomal enzyme activities were measured and expressions of autophagy-related genes (mTOR, ATG8, and ATG12) were analyzed by qRT-PCR. The results showed that, depending on the time of onset of starvation stress, autophagy plays no role as an adaptive response under starvation conditions or occurs at a much more moderate level than autophagy which happens as part of cell death during larval-pupal metamorphosis.