Histological and molecular analysis of selenium synergistic RNAi of Dynamin gene in Bombyx mori

Selenium (Se) is an essential element for animals, regulating various biochemical processes as well as growth and development. Our previous study showed that 50 μM Se significantly affected the silkworm, Bombyx mori by targeting dynamin, a key endocytosis protein, at 24 h. Here, we explored the hemolymph metabolite levels and silk gland gene expression in B. mori under different treatments. Non-targeted metabolomics analyses revealed 297 differential metabolites (80 up-regulated and 217 down-regulated) in the dynamin knockdown group and 295(204 up and 91 down) in the Se additive group, including amino acids, sugars, lipids, nucleotide metabolites, and their derivatives. The knockdown enhanced aspartate biosynthetic but weakened glycolysis/gluconeogenesis, the TCA cycle, purine metabolism, alanine and glutamate metabolic pathways. In contrast, Se significantly enhanced glycolysis/gluconeogenesis, the TCA cycle, purine metabolism, and alanine,/aspartate/ glutamate pathways while inhibiting lysine biosynthesis. Transcriptomic analysis of the silk gland identified 705 differentially expressed genes (DEGs) (320 up and 385 down) in the knockdown group and 2907 DEGs (2714 up and 193 down) in the Se group. Knockdown affected protein processing, MAPK signaling, and endocytosis, while Se impacted glutathione metabolism, spliceosome, and peroxisomal pathways. These DEGs are linked to protein processing, energy provision, and antioxidants. This study elucidates the metabolic and transcriptional changes due to Se-associated RNAi stress (dynamin knockdown) on silkworms, highlighting their roles in key physiological processes.