Due to industrial, rural, and domestic waste disposal, heavy metals such as cadmium (Cd), chromium (Cr), lead (Pb), zinc (Zn), copper (Cu), and iron (Fe) continually infiltrate aquatic environments. These pollutants do not degrade naturally and, thus, have a high capacity for bioaccumulation in tissues and organs. The present study uses histological and immunohistochemical analyses to evaluate the contamination status of Salminus franciscanus, a large and economically important fish. Levels of Cd, Cr, Pb, Zn, Cu, and Fe were evaluated by atomic absorption spectrometry in the liver and muscle of fish sampled from two tributaries of the upper São Francisco River Basin, Brazil: the Abaeté and Paraopeba Rivers. In addition, histopathological alterations and expressions of three environmental biomarkers were assessed: metallothionein (MT), heat shock protein-70 (HSP70), and cytochrome P450-1A (CYP1A). The results show that fish from the Paraopeba River are unsuitable for human consumption, with several metals being detected above the safe limits established by the World Health Organization. Histopathological alterations in the liver and spleen were also significantly more frequent in fish from the Paraopeba River than in those from the Abaeté River (P < 0.05). Significant differences in the expressions of environmental biomarkers were observed between the rivers. Fish from the Abaeté River presented significantly higher values of the gonadosomatic index (GSI) and lower levels of metal contamination in the liver and muscle.

中文翻译：

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高消耗巴西鱼类中的重金属污染：免疫组织化学和组织病理学评估。

由于工业，农村和家庭废物的处理，镉（Cd），铬（Cr），铅（Pb），锌（Zn），铜（Cu）和铁（Fe）等重金属不断渗透到水生环境中。这些污染物不会自然降解，因此具有很高的组织和器官生物蓄积能力。本研究使用组织学和免疫组化分析来评估Salminus Franciscanus的污染状况，一种大型且具有重要经济意义的鱼。通过原子吸收光谱法评估了从巴西圣弗朗西斯科河上游流域的两个支流：Abaeté河和Paraopeba河取样的鱼的肝脏和肌肉中Cd，Cr，Pb，Zn，Cu和Fe的水平。此外，评估了三种环境生物标志物的组织病理学改变和表达：金属硫蛋白（MT），热休克蛋白70（HSP70）和细胞色素P450-1A（CYP1A）。结果表明，帕拉奥佩巴河的鱼类不适合人类食用，其中几种金属的含量超过了世界卫生组织规定的安全极限。帕拉奥佩巴河鱼类的肝脏和脾脏的组织病理学改变也比阿巴埃特河的鱼类更常见（P <0.05）。在河流之间观察到环境生物标志物表达的显着差异。来自Abaeté河的鱼的性腺体指数（GSI）值显着较高，而肝脏和肌肉中的金属污染水平较低。