Cadmium (Cd) is a hazardous environmental contaminant, which has a serious effect on the ecosystem, food safety and human health. Scallop could accumulate high concentration of Cd from the environment and has been regarded as a Cd hyper-accumulator. In this work, we investigated the antioxidative defense, detoxification and transport of Cd in the kidneys of scallops by transcriptome analysis. A total of 598 differentially expressed genes including 387 up-regulated and 211 down-regulated ones were obtained during Cd exposure, and 46 up-regulated and 260 down-regulated ones were obtained during depuration. Cadmium exposure could cause oxidative stress in the kidneys, which was particularly shown in the pathways involved in proteasome and oxidative phosphorylation. The mRNA expression of 5 metallothionein (MT) genes were overexpressed under Cd exposure and significantly decreased during Cd depuration, which played a vital role in Cd chelation and detoxification. The expression of divalent metal transporter (DMT) genes were down-regulated insignificantly during accumulation and depuration of Cd, which suggested that the DMT played little roles in Cd transport in scallops. A positive relationship in the expression of the zinc transporter (ZIP6 and ZIP1) genes with Cd exposure and depuration was observed, which confirmed its important role for Cd uptake in the kidneys of scallops. 26S proteasome activities and MT expression were Cd-dependent. This study supplied the important reference on the hyperaccumulation of Cd by scallops and identified some effective bioindicators for the environmental risk assessment.

镉（Cd）是一种危险的环境污染物，对生态系统、食品安全和人类健康具有严重影响。扇贝可以从环境中积累高浓度的镉，被认为是镉的超富集物。在这项工作中，我们通过转录组分析研究了扇贝肾脏中 Cd 的抗氧化防御、解毒和转运。Cd暴露共获得598个差异表达基因，其中上调387个，下调211个，净化过程中获得上调46个，下调260个。镉暴露可能导致肾脏出现氧化应激，这在涉及蛋白酶体和氧化磷酸化的途径中尤为明显。5 个金属硫蛋白（MT）基因的 mRNA 表达在 Cd 暴露下过表达，在 Cd 净化过程中显着降低，这在 Cd 螯合和解毒中起着至关重要的作用。在镉的积累和净化过程中二价金属转运蛋白（DMT）基因的表达下调不显着，这表明DMT在扇贝中镉的转运中起很小的作用。观察到锌转运蛋白（ZIP6 和 ZIP1）基因的表达与 Cd 暴露和净化呈正相关，这证实了它在扇贝肾脏吸收 Cd 中的重要作用。26S 蛋白酶体活性和 MT 表达是 Cd 依赖性的。该研究为扇贝对Cd的超富集提供了重要参考，并为环境风险评估确定了一些有效的生物指标。