BACKGROUND Harbour porpoises Phocoena phocoena from the southern North Sea are known to display high levels of Zn and Hg in their tissues linked to their nutritional status (emaciation). The question arises regarding a potential role of metallothioneins (MTs) with regard to these high metal levels. In the present study, metallothionein detection and associated Zn, Cd, Cu and Hg concentrations were investigated in the liver and kidney of 14 harbour porpoises collected along the Belgian coast. RESULTS Metallothioneins seemed to play a key role in essential metal homeostasis, as they were shown to bind 50% of the total hepatic Zn and 36% of the total hepatic Cu concentrations. Renal MTs also participated in Cd detoxification, as they were shown to bind 56% of the total renal Cd. Hg was mainly found in the insoluble fraction of both liver and kidney. Concomitant increases in total Zn concentration and Zn bound to MTs were observed in the liver, whereas Zn concentration bound to high molecular weight proteins remained constant. Cu, Zn and Cd were accumulated preferentially in the MT fraction and their content in this fraction increased with the amount in the hepatocytosol. CONCLUSION MTs have a key role in Zn and Cu homeostasis in harbour porpoises. We demonstrated that increasing hepatic Zn concentration led to an increase in Zn linked to MTs, suggesting that these small proteins take over the Zn overload linked to the poor body condition of debilitated harbour porpoises.

中文翻译：

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Zn，Cu，Cd和Hg与来自北海南部的海豚海豚（Phocoena phocoena）中的金属硫蛋白结合。

背景技术已知来自北海南部的海豚海豚（Phocoena phocoena）在其组织中显示出高水平的锌和汞，这与它们的营养状况（消瘦）有关。关于金属硫蛋白（MTs）在这些高金属含量方面的潜在作用提出了一个问题。在本研究中，调查了沿比利时海岸采集的14只海豚的肝脏和肾脏中金属硫蛋白的含量及相关的Zn，Cd，Cu和Hg浓度。结果金属硫蛋白似乎在基本金属稳态中起关键作用，因为它们被证明结合了总肝Zn的50％和总肝Cu浓度的36％。肾脏MTs也参与了Cd排毒，因为它们被证明结合了总肾脏Cd的56％。汞主要存在于肝脏和肾脏的不可溶部分。在肝脏中观察到总锌浓度和与MTs结合的Zn的同时增加，而与高分子量蛋白质结合的Zn浓度保持恒定。Cu，Zn和Cd在MT组分中优先积累，并且其含量随肝细胞溶胶含量的增加而增加。结论MTs在港口豚鼠体内的Zn和Cu稳态中起关键作用。我们证明增加的肝Zn浓度导致与MTs相关的Zn的增加，表明这些小蛋白接管了与衰弱的港湾豚鼠身体状况不佳相关的Zn超载。Zn和Cd优先积累在MT组分中，并且其含量随肝细胞溶胶含量的增加而增加。结论MTs在港口豚鼠体内的Zn和Cu稳态中起关键作用。我们证明增加的肝Zn浓度导致与MTs相关的Zn的增加，表明这些小蛋白接管了与衰弱的港湾豚鼠身体状况不佳相关的Zn超载。Zn和Cd优先积累在MT组分中，并且其含量随肝细胞溶胶含量的增加而增加。结论MTs在港口豚鼠体内的Zn和Cu稳态中起关键作用。我们证明增加的肝Zn浓度导致与MTs相关的Zn的增加，表明这些小蛋白接管了与衰弱的港湾豚鼠身体状况不佳相关的Zn超载。