Starvation-induced changes in the proteome and transcriptome of the salivary glands of leech (Hirudo nipponia).

Hirudo nipponia is an important medicinal animal in China. Its salivary gland secretions contain a variety of protein bioactive substances. Investigations of its salivary glands are of great significance in the study of the medicinal value and mechanism of leech secretions. Illumina RNA-Seq technology was used to perform transcriptome sequencing of salivary gland tissue of H. nipponia under starvation (D30) and fed (D0) states. A total of 2,650 differentially expressed genes (DEGs) were screened. Using the label-free protein quantification technique and bioinformatics analysis, the expression of differentially expressed proteins (DEPs) in the salivary gland tissue of H. nipponia was compared. A total of 2,021 proteins were identified, among which 181 proteins were differentially expressed between the starvation and fed states, with 72 significantly upregulated and 109 significantly downregulated. The salivary glands of H. nipponia synthesized protein-based active substances after 30 days of starvation and adapted to the starvation environment by weakening respiratory activity and reducing metabolic activity to reduce energy expenditure. Energy was produced by glycolysis and the tricarboxylic acid cycle for the synthesis of substances such as antibiotics. This study combined transcriptome and proteome sequencing data to provide a data reference for an in-depth study of the regulatory mechanism of salivary gland secretions of H. nipponia under starvation stress by analyzing DEGs and DEPs.