Comparative transcriptome analysis of silkworm, Bombyx mori colleterial gland suggests their functional role in mucous secretion.

Colleterial glands (CG) present in the body of adult female of Bombyx mori, which can help adhere eggs on the surface of the host plants. Although this organ has been known for centuries, only morphology and its secretions have been studied. Their gene expression profiles and physiological roles remain largely unknown. Aided by high-throughput next generation sequencing (NGS), we reported the comparative transcriptome analysis of CG isolated from the H9 and the P50 strains of Bombyx mori. A total of 19,896,957 and 20,446,366 clean reads were obtained from CG of H9 and the P50 strains, respectively; then differential expression analysis was performed, and 1,509 differentially expressed genes (DEGs) were identified. Among them, 1,001 genes are up-regulated and 508 genes are down-regulated in P50 individuals compared with H9 individuals. The enrichment of GO (Gene Ontology) and KEGG (Kyoto Encyclopedia of Genes and Genomes) of DEGs confirmed that many DEGs were associated with "Amino acid transport and metabolism", "Nucleotide transport and metabolism", and "Inorganic ion transport and metabolism", 25 of the DEGs related to the "ECM-receptor interaction passway", "sphingolipid metabolism passway", and "amino sugar and nucleotide sugar metabolism passway" were potentially involved in the process of CG development and mucus secretion. According to these data, we hypothesized that CG play an important role in providing favorable physiological environment for the glue secretion formation. In addition, GO enrichment and differential expression analysis of the DEGs in the CG indicate that this gland may be involved in the transporting of small solutes such as sugars, ions, amino acids and nucleotide sugar to the CG. Our findings lay the foundation for further research on CG function.