Rising seawater temperatures associated with global warming have caused mass mortality of Yesso scallops in aquaculture, resulting in severe economic losses. Although heat-responsive genes and the diversified hsp gene family have been described, direct functional evidence for genes that enhance heat tolerance in scallops has been limited. In this study, we used a gene overexpression system based on primary scallop hemocytes to functionally assess the roles of hsp genes in heat resistance. Transcriptome data screening identified 13 HSP-related genes expressed in scallop hemocytes. Heat-exposure experiments revealed that hsc71 , hsp60 , hsp70-12 A , and hsp70–14 were upregulated in circulating hemocytes under high-temperature condition at 24 °C. Using the hemocyte-based overexpression system, we expressed scallop Hsp-GFP fusion proteins and confirmed their proper expression with distinct subcellular localization. Hemocytes expressing the fusion proteins were then subjected to heat treatment, and cell viability was measured using a luminescence-based assay. The results suggest that scallop hsc71 and hsp60 contribute to improved cell survival at 30 °C. This study demonstrates the feasibility of functional gene validation using hemocytes as an overexpression platform and provides cellular-level evidence that HSP-mediated cytoprotection may contribute to thermal tolerance in scallops, thereby offering a functional framework for evaluating stress resilience in aquaculture species. • Hemocytes constitutively expressed 13 HSP-related genes in the Yesso scallop. • Heat exposure induced the upregulation of 4 HSP-related genes in hemocytes. • Overexpression of hsc71 and hsp60 enhanced cellular heat resistance in hemocytes. • HSP-mediated cytoprotection may contribute to thermal tolerance in the Yesso scallop.
Matsusaka et al. (2026) studied this question.