Cadmium-induced ultrastructural changes and apoptosis in the gill of freshwater mussel Anodonta woodiana

• Published in: Environmental science and pollution research international Vol. 29; no. 16; pp. 23338 - 23351
• Main Authors: Li, Yong Quan, Chen, Chien M., Liu, Na, Wang, Lan
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01-04-2022; Springer Nature B.V
• Subjects: Abnormalities; Acute toxicity; Anodonta woodiana; Apoptosis; Aquatic Pollution; Atmospheric Protection/Air Quality Control/Air Pollution; Ca2+-transporting ATPase; Cadmium; Caspase-3; Caspase-8; Caspase-9; Chromatin; Cristae; Deoxyribonucleic acid; Disintegration; DNA; DNA fragmentation; Earth and Environmental Science; Ecotoxicology; Electrophoresis; Endoplasmic reticulum; Environment; Environmental Chemistry; Environmental Health; Environmental science; Enzymatic activity; Epithelial cells; Epithelium; Fragmentation; Gel electrophoresis; Gills; Golgi apparatus; Hydrogen peroxide; Ladders; Membranes; Mitochondria; Mollusks; Mussels; Proteins; Research Article; Toxicity; Ultrastructure; Waste Water Technology; Water Management; Water Pollution Control; Ca-ATPase; DNA fragmentation; Caspase; H; Morphological change; Heavy metal; Acute toxicity; O
• ISSN: 0944-1344; 1614-7499
• DOI: 10.1007/s11356-021-16877-w

This study investigated the acute toxicity of cadmium (Cd) to the freshwater mussel
Anodonta woodiana
. The freshwater mussels were exposed to five concentrations of Cd (0 mg/L, 8.43 mg/L, 16.86 mg/L, 33.72 mg/L, and 67.45 mg/L) for up to 96 h. The 24-h, 48-h, 72-h, and 96-h LC
50
values for Cd were estimated as 562.3 mg/L, 331.1 mg/L, 182.0 mg/L, and 134.9 mg/L, respectively. Caspase-3, caspase-8, caspase-9, and Ca-ATPase activities; protein and H
2
O
2
levels; DNA fragmentation; and ultrastructure of the gill were also investigated. The activities of caspase-3 and caspase-9 in mussels were increased by Cd in a dose-dependent manner, where higher doses of Cd (33.72 mg/L and 67.45 mg/L) significantly increased the enzyme activities compared to the controls (
P
 < 0.05). The caspase-8 activity was significantly depressed by a low dose of Cd (8.43 mg/L) but was clearly induced by higher doses of Cd (16.86 mg/L, 33.72 mg/L, and 67.45 mg/L) (
P
 < 0.05). The Ca-ATPase activity and H
2
O
2
levels were elevated and reached maximum values under the medium dose of Cd (16.86 mg/L). However, protein levels were decreased by Cd in an inverse dose–dependent manner. In the gills of the mussels, Cd treatment induced DNA fragmentation as demonstrated by DNA ladders observed via agarose gel electrophoresis. Moreover, ultrastructural alterations in gill cells of mussels treated with Cd (16.86 mg/L and 67.45 mg/L) for 96 h were observed by electronic microscopy. The ultrastructure abnormalities were characterized by the following features: (1) a disordered arrangement and breaking off of microvilli of epithelial cells; (2) chromatin condensed near the nuclear membrane and the appearances of extremely irregular nuclei, some with a fingerlike shape and an unclear, swollen, invaginated, or ruptured nuclear membrane and apoptotic bodies; (3) swollen and vacuolating mitochondria, some with disintegrated or missing cristae; (4) a disintegrated rough endoplasmic reticulum containing different sizes of vesicles; and (5) shrinking and deformation of Golgi bodies with decreased vesicle numbers. Our results demonstrated that Cd could activate caspase-3, caspase-8, caspase-9, and Ca-ATPase; cause ultrastructural changes; and produce DNA fragmentation in the mussels investigated. Based on the information obtained through this study, it is reasonable to conclude that Cd can induce apoptosis in the gills of the mussels, eventually leading to tissue damage.