Spermidine supplementation during the 5th instar larval stage alters the silk gland transcriptome in Bombyx mori

Spermidine is known to play role in various cellular and biological processes. It enhances transcription and regulates gene expression. During the fifth instar stage, Bombyx mori larvae show exponential growth and active silk production by extensive DNA replication, transcription, and translation in silk glands. The current study investigated the effect of spermidine supplementation on the silk gland transcriptome at the feeding and spinning stages. The Bombyx mori larvae were divided into two groups, control and spermidine, at the beginning of the 5th instar stage. Silk glands were isolated on the last day of the feeding and spinning stages from both groups. RNA sequencing was performed using the Illumina paired–end sequencing platform. Spermidine supplementation showed enhanced expression of genes involved in lipid metabolism, signalling, growth, and developmental pathways at the feeding stage, whereas secretory, post-translational modification, stress response, and developmental pathways at the spinning stage. Thus, the results of the present study indicate that spermidine exerts complex transcriptional regulation in the silk glands of Bombyx mori.