Transcriptomic Analysis Reveals the Mechanisms of Cadmium Transport and Detoxification in Portuguese Oysters (Crassostrea angulata)

Oysters are a globally distributed aquatic economic shellfish with a remarkable ability to accumulate cadmium (Cd). The phenomenon of Cd content exceeding safety standards in oysters occurs frequently, posing a significant risk to food safety. In this study, Portuguese oysters (<i>Crassostrea angulata</i>) were exposed to 2 μg/L of Cd for 15 days. Individuals with significantly different Cd accumulation were selected for transcriptomic sequencing analysis. KEGG enrichment analysis revealed that the differentially expressed genes (DEGs) between high- and low-Cd-accumulation individuals, as well as those before and after Cd exposure, were primarily enriched in metabolic pathways (33.8%) and organismal systems (32.2%). ABC transporters, phagosomes, glutathione metabolism, and the biosynthesis of amino acids played crucial roles in Cd accumulation and detoxification processes. Metal cation transport-related genes, including <i>zip1</i>, <i>copt5.1</i>, and <i>orct2</i>, may be involved in the Cd transport process in Portuguese oysters, and their differential expression influences Cd accumulation in the soft tissues. Meanwhile, genes such as <i>sod3</i>, <i>cyp4f22</i>, and <i>abca3</i> are likely to play significant roles in detoxification under Cd exposure. Additionally, alternative splicing analysis identified 13 potential genes associated with Cd response in Portuguese oysters, including <i>cs2</i>, <i>gfpt1</i>, and <i>acox1</i>.