Growth performance and intestinal transcriptomic responses of Babylonia areolata at two daily water-exchange rates

A total of 820 differentially expressed genes were identified between the H and L groups, of which 370 genes showed higher expression in the H group and 450 genes showed higher expression in the L group. GO and KEGG enrichment analyses showed that the differentially expressed genes were mainly involved in innate immunity and stress responses, amino acid and related small-molecule metabolism, and signal regulation. GSEA further revealed enrichment of gene sets associated with ubiquitin-related processes, endopeptidase inhibitor activity, regulation of cell death, and the biosynthesis of amino acids, organic acids, and small molecules.

The expression trends of five candidate genes determined by qRT-PCR were generally consistent with the RNA-Seq results, with two genes showing significant differences. Overall, 50% and 100% daily water exchange rates did not result in significant divergence in growth or survival phenotypes of B. areolata under the present experimental conditions, but induced selective transcriptional regulation related to intestinal immune stress, metabolism, and cellular homeostasis.