Spermidine Reshapes the Silk Gland Transcriptome in Silkworm Larvae

Spermidine supplementation during the fifth instar larval stage changes the expression of large sets of genes in the silk glands of the silkworm, Bombyx mori, according to a Research Note published in BMC Research Notes on 28 October 2026. The study, led by Brinda Goda Lakshmi Didugu, Shamitha Vodithala and Anitha Mamillapalli, used RNA sequencing to compare the transcriptomes of silk glands from treated and untreated larvae at two distinct developmental points.

Spermidine is a naturally occurring polyamine known to participate in a range of cellular and biological processes, including the enhancement of transcription and the regulation of gene expression. The fifth instar is a critical window in the silkworm life cycle: during this stage, larvae grow exponentially and produce silk actively, supported by extensive DNA replication, transcription and translation within the silk glands. The authors set out to investigate how supplementing larvae with spermidine at the beginning of this stage would affect the silk gland transcriptome at the feeding and spinning stages.

In the experiment, larvae were divided into two groups, a control group and a spermidine-treated group, at the start of the fifth instar. Silk glands were isolated from both groups on the last day of the feeding stage and on the last day of the spinning stage, and RNA sequencing was carried out on an Illumina paired-end sequencing platform.

The sequencing results showed stage-specific patterns of transcriptional change. At the feeding stage, spermidine supplementation was associated with enhanced expression of genes involved in lipid metabolism, signalling, and growth and developmental pathways. At the spinning stage, the enhanced expression instead involved genes linked to secretory processes, post-translational modification, stress response, and developmental pathways. The authors note that these results indicate spermidine exerts complex transcriptional regulation in the silk glands of Bombyx mori.

The study is reported as a data description in the journal’s Research Notes format, and the published version is an open-access article carrying a permanent DOI. Because the report describes transcriptomic observations in larval silk glands, its findings concern gene expression patterns in this insect tissue and do not extend to applications in other organisms or to silk production outcomes, which were not reported in the abstract. The stage-specific shifts in expression, from metabolic and growth-related genes during feeding to secretory, stress-response and modification-related genes during spinning, provide a detailed picture of how a single dietary supplement can coincide with different transcriptional programs as the larvae transition from feeding to spinning.

Subject of Research: Effects of spermidine supplementation on the silk gland transcriptome of fifth instar Bombyx mori larvae

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

Article References: Didugu, B. G. L., Vodithala, S., & Mamillapalli, A. (2026). Spermidine supplementation during the 5th instar larval stage alters the silk gland transcriptome in Bombyx mori. BMC Research Notes. https://doi.org/10.1186/s13104-026-08087-9

Image Credits: AI Generated

DOI: 10.1186/s13104-026-08087-9

Keywords: spermidine, Bombyx mori, silkworm, silk gland, transcriptome, RNA sequencing, fifth instar, gene expression, polyamines, feeding stage, spinning stage, BMC Research Notes