Expression of metallothionein in the liver and kidneys of the red deer (Cervus elaphus L.) from an industrial metal smelting area of Poland

- The coding sequence of the red deer (MT1) gene was identified and characterized.
- Levels of Cd, Pb, Cu and Zn in tissues differed between collection sites.
- Expression of MT1 in red deer was analyzed by RT-qPCR and immunohistochemistry.
- No relationship was found between MT1 expression and Cd levels in red deer.
- Correlations between MT1 expression and Cu, Zn and age were found.

The metallothionein 1 (MT1) coding sequence of red deer was identified and compared to orthologous sequences from other mammals. Over 90% identity was observed between red deer MT1 amino acid sequence and MT1 sequences of other ruminants. Liver and kidney samples of red deer were collected from the industrial zinc smelting site of Miasteczko Slaskie and from the Masuria Lake District serving as a pollution-free control site. The concentrations of cadmium (Cd), lead (Pb), copper (Cu) and zinc (Zn) were analyzed by the atomic absorption spectrometry technique (AAS). The levels of Cd in the liver of red deer from the metal smelting region was about 8 times higher than for the reference control site. Next, the expression of MT1 mRNA in the liver of red deer was quantified by the reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and the expression of MT1/2 protein in the liver and kidneys was analyzed by immunohistochemistry. Positive correlations were found between expression levels for MT1 mRNA and the concentrations of Cu and Zn in liver of red deer, and with the age of animals. Immunohistochemical staining demonstrated the nuclear and cytoplasmatic expression in both liver and kidney tissues, but with no obvious relationship shown for the expression of MT1/2 protein and tissue metal levels. Our results showed that the analysis of MT expression levels in the red deer could not be used independently as a biomarker for identifying exposure to Cd, but could be co-analyzed with tissue metal levels to give better prognosis for environmental exposure to metals.

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