Abstract
BACKGROUNDS: The marine diatom Ditylum brightwellii has been widely used as a model species for ecotoxicological assessments in marine environments. Heat shock proteins (Hsps) function as molecular chaperones that protect cells under diverse stress conditions. Of them, Hsp104 participates in the protein restoration system by reversing protein aggregation. METHODS: In the present study, we determined the full-length sequence of DbHsp104 in D. brightwellii using transcriptome sequencing and gene cloning. RESULTS: The open reading frame (ORF) was 2745 bp in length, encoding a protein of 915 amino acids (101.15 kDa). Phylogenetic and domain structural analysis revealed that DbHsp104 possesses conserved features of eukaryotic Hsp104. In addition, transcriptional responses of the gene were evaluated after exposures to thermal stress at 20, 25, and 30 °C, and heavy metals and endocrine-disrupting chemicals (EDCs) for 24 h. Relative gene expression analysis showed that DbHsp104 was significantly up-regulated under thermal stress and copper exposures, peaking at 4.87- and 5.55-fold (p < 0.001) increases, respectively. In contrast, no significant changes were observed in response to nickel, bisphenol A (BPA), polychlorinated biphenyl (PCB), and endosulfan (EDS) treatments. CONCLUSIONS: These results suggest that DbHsp104 is specifically responsive to acute stress induced by thermal stress and copper, highlighting its potential as a molecular biomarker in marine environments.