Enzyme activity and morphological change in the spleens of crucian carp in the Yongcheng coal mine subsidence area, China

The goal of the current study was to investigate the effects of pollution on aquatic organisms in the Yongcheng coal mine subsidence area. Crucian carp (Carassius auratus) were collected from Yongcheng natural fishpond (experimental group) and Tianmu Lake (control group), and the spleens were isolated for analysis. Subsequently, histological changes, DNA damage, and antioxidant enzyme activity were assessed. The result showed that there were more vacuoles, widened blood sinus cavities, increased partial dot necrosis, and a larger number of brown-yellow nodules in splenic sections stained with hematoxylin and eosin in the experimental group than in the control group. Additionally, it was not easy to distinguish red pulp from white pulp in the experimental group. The antioxidant enzyme activity in the experimental group was significantly lower than that in the control group (P < 0.01). Comet assay results showed varying degrees of tailing and DNA chain breaks in the experimental group, and further analysis demonstrated that the tail length and tail moment were significantly increased compared to those in the control group (P < 0.01). These results suggest that the spleen antioxidant defense system was severely damaged in crucian carp from the Yongcheng coal mine subsidence area.