Integrated mortality rates and transcriptome comparative analysis between wild and artificially selected ark shell...

The survival ability of artificially selected ark shells (Scapharca subcrenata) and wild populations was assessed under different combinations of temperatures (25, 27, 29, and 31 °C) and Vibrio anguillarum immersion concentrations (0, 3 × 10⁸, 6 × 10⁸, 9 × 10⁸, 12 × 10⁸, 15 × 10⁸, and 18 × 10⁸ CFU/mL). Significant differences in mortality rates between the two ark shell populations were observed across most temperature and immersion concentration combinations, with only a few exceptions. The gene expression profiles of selected and wild ark shells were analyzed through transcriptome sequencing following exposed to 1 × 10⁸ CFU/mL of V. anguillarum strain PL2. Gene Ontology (GO) functional classification of the 1558 differentially expressed genes (DEGs) common to the three comparisons revealed that 'cellular process', 'membrane' and 'binding' were the most enriched terms across the biological process, cellular component, and molecular function categories in the D (treated wild ark shells) _vs_C (Untreated wild ark shells were used as the control group) and KD (treated selectively bred ark shells) _vs_D groups. COG analysis reveals that the 'Energy Production and Conversion' category is significantly downregulated in the KD_vs_D comparison compared to the D_vs_C and C_vs_KD comparisons. Heatmap visualization of DEGs across C, D, and KD groups showed numerous genes exhibiting inverse expression trends among the groups. Among the top 10 KEGG pathways identified across the three comparison groups, no pathways were shared between the KD_vs_D group and the other two comparisons, suggesting that these pathways may be related to the resistance of ark shells to V. anguillarum. Our study indicates that ark shell populations selected under high-intensity environmental stress exhibit greater tolerance to elevated temperatures and V. anguillarum. This further demonstrates that selecting ark shells under stress conditions may enhance their survival rates in aquaculture. These findings will deepen the understanding of bivalve adaptability to environmental changes and aid in the advancement of shellfish aquaculture practices.