Transcriptomic investigation and biomarker discovery for zinc response in oysters Crassostrea gasar

Clarissa P Ferreira; Renato S Moreira; Camila L V Bastolla; Miguel Saldaña-Serrano; Daína Lima; Carlos H A M Gomes; Afonso C D Bainy; Karim H Lüchmann

doi:10.1016/j.margen.2024.101109

Transcriptomic investigation and biomarker discovery for zinc response in oysters Crassostrea gasar

Mar Genomics. 2024 Apr 10:75:101109. doi: 10.1016/j.margen.2024.101109. Online ahead of print.

Authors

Clarissa P Ferreira¹, Renato S Moreira², Camila L V Bastolla³, Miguel Saldaña-Serrano³, Daína Lima³, Carlos H A M Gomes⁴, Afonso C D Bainy³, Karim H Lüchmann⁵

Affiliations

¹ Multicentric PostGraduate Program in Biochemistry and Molecular Biology - PMBqBM, Santa Catarina State University, Lages 88520-000, Brazil.
² Federal Institute of Santa Catarina, Gaspar 89111-009, Brazil; Bioinformatic Laboratory, Federal University of Santa Catarina, Florianópolis 88040-970, Brazil.
³ Laboratory of Biomarkers of Aquatic Contamination and Immunochemistry - LABCAI, Federal University of Santa Catarina, Florianópolis 88034-257, Brazil.
⁴ Laboratory of Marine Mollusks (LMM), Department of Aquaculture, Center of Agricultural Science, Federal University of Santa Catarina, UFSC, Florianópolis, Santa Catarina, Brazil.
⁵ Department of Scientific and Technological Education, Santa Catarina State University, Florianópolis 88035-001, Brazil. Electronic address: karim.luchmann@udesc.br.

PMID: 38603950
DOI: 10.1016/j.margen.2024.101109

Abstract

In an era of unprecedented industrial and agricultural growth, metal contamination in marine environments is a pressing concern. Sentinel organisms such as the mangrove oyster Crassostrea gasar provide valuable insights into these environments' health. However, a comprehensive understanding of the molecular mechanisms underlying their response to metal exposure remains elusive. To address this gap, we reanalyzed the 454-sequencing data of C. gasar, utilizing an array of bioinformatics workflow of CDTA (Combined De Novo Transcriptome Assembly) to generate a more representative assembly. In parallel, C. gasar individuals were exposed to two concentrations of zinc (850 and 4500 μg L^-1 Zn) for 48 h to understand their molecular responses. We utilized Trinotate workflow for the 11,684-CDTA unigenes annotation, with most transcripts aligning with the genus Crassostrea. Our analysis indicated that 67.3% of transcript sequences showed homology with Pfam, while 51.4% and 54.5%, respectively had GO and KO terms annotated. We identified potential metal pollution biomarkers, focusing on metal-related genes, such as those related to the GSH biosynthesis (CHAC1 and GCLC-like), to zinc transporters (ZNT2-like), and metallothionein (MT-like). The evolutionary conservation of these genes within the Crassostrea genus was assessed through phylogenetic analysis. Further, these genes were evaluated by qPCR in the laboratory exposed oysters. All target genes exhibited significant upregulation upon exposure to Zn at both 850 and 4500 μg L^-1, except for GCLC-like, which showed upregulation only at the higher concentration of 4500 μg L^-1. This result suggests distinct activation thresholds and complex interactions among these genes in response to varying Zn concentrations. Our study provides insights into the molecular responses of C. gasar to Zn, adding valuable tools for monitoring metal pollution in marine ecosystems using the mangrove oyster as a sentinel organism.

Keywords: Bioinformatics; Ecotoxicology; Gene expression; Metal pollution; Zinc exposure.