Heavy Metal Levels and Metallothionein mRNA Expressions in Wild Crucian Carp (Carassius auratus auratus) from Hun River
浑河野生鲫鱼体内重金属污染水平与金属硫蛋白基因表达

To study the potential ecological risk of heavy metal contamination in Hun River, the contents of heavy metals in different tissues of wild crucian carps from Hun River were analyzed, and the metallothionein mRNA expressions in gill and hepatic tissues were also investigated. Results showed that the accumulation amounts of Cr, Cd, Pb, Cu and Zn in tissues followed the order of intestine>liver>gill>muscle. Zn content was the highest, ranging from 17.49 to 176.01 mg·kg-1 (wet weight), and Cd content was the lowest, ranging from non-detectable level to 0.57 mg·kg-1 (wet weight). The average pollution index assessment results showed that the wild crucian carps in Hun River were slightly contaminated by heavy metals Furthermore, the pollution level in wild crucian carps increased from upstream to downstream. Among the studied heavy metals, the contents of Cr, Pb and Zn mostly contributed to the pollution index. The metallothionein mRNA expression levels in livers of crucian carps detected with real-time quantitative polymerase chain reaction were found to increase from upstream to downstream. A positive relationship was observed between the metallothionein mRNA expression levels in livers and the average pollution index in muscles (R2=0.71), indicating that the metallothionein gene can be used as a promising biomarker for monitoring the heavy metal contamination.