Bioenergetic effects of aqueous copper and cadmium on the grass shrimp, Palaemonetes pugio

Physiological and histological effects of cadmium, lead, and combined on Artemia franciscana

This study analyzed the effects of cadmium (Cd) and lead (Pb) on growth, sexual couples, and histological structures of Artemia franciscana exposed to individual concentrations of these metals and combined. No histological effects were observed at tissue level in digestive, respiratory, nervous, and reproductive systems (i.e., necrosis, loss of regular structure) in individual and mixed applications on A. franciscana for 20 days of exposure. No significant differences (p > 0.05) were determined in final size and growth rate among the organisms exposed to Cd and those of control. For Pb, only the final size (3.59 ± 0.59 mm) of organisms exposed to the highest concentration was significantly lower (p < 0.05) than those of the control (4.53 ± 0.34 mm) group, whereas for the combined experiment, no significant differences (p > 0.05) were observed in final size and growth rate. At all Cd concentrations, mean sexual couples were significantly lower (p < 0.05) than those of the control, as well as for Pb. For the combined experiment (8 μg/L of Cd + 8 μg/L of Pb), sexual couples were not observed, indicating synergism and negative reproduction effects. The results showed that Cd and Pb aquatic environmental regulations (as the Criterion of Continuous Concentration) proposed by the US Environmental Protection Agency (EPA) should include their interactions with other metals.

Toxic effects of metal copper stress on immunity, metabolism and pathologic changes in Chinese mitten crab (Eriocheir japonica sinensis)

Copper (Cu²⁺), which represents a major physiological challenge for crab culture, is ubiquitous in the aquatic culture environment, and gills are the first organs that come into direct contact with the environment. However, the molecular basis of the response of crabs to Cu²⁺ stress remains unclear. Here, we conducted a transcriptome and differential expression analysis on the gills from Chinese mitten crab unexposed and exposed to Cu²⁺ for 24 h. The comparative transcriptome analysis identified 2486 differentially expressed genes (DEGs). GO functional analysis and KEGG pathway analysis revealed some DEGs, which were mostly related to immunity, metabolism, osmotic regulation, Cu²⁺ homeostasis regulation, antioxidant activity, and detoxification process. Some pathways related to humoral and cellular immunity, such as phagosome, peroxisome, lysosome, mTOR signaling pathway, PI3K-Akt signaling pathway, Toll-like receptor signaling pathway, and T cell receptor signaling pathway were enhanced under Cu²⁺ stress. In addition, Cu²⁺ stress altered the expression patterns of key phagocytosis and apoptosis genes (lectin, cathepsin L, Rab7, and HSP70), confirming that Cu²⁺ can induce oxidative stress and eventually even apoptosis. Histological analysis revealed that the copper can induce damage at the cellular level. This comparative transcriptome analysis provides valuable molecular information to aid future study of the immune mechanism of Chinese mitten crab in response to Cu²⁺ stress and provides a foundation for further understanding of the effects of metal toxicity.

Inhibitory properties of some heavy metals on carbonic anhydrase I and II isozymes activities purified from Van Lake fish (Chalcalburnus Tarichi) gill

In this study, CA I and II isoenzymes were purified from Van Lake fish gills by using Sepharose-4B-L-tyrosine-sulfanilamide affinity chromatography and to determine the effects of some metals on the enzyme activities. For purified CA I isoenzyme, yield, specific activity, and purification fold were obtained as 42.07%, 4948.12 EU/mg protein, and 116.61 and for CA II isoenzyme, 7%, 1798.56 EU/mg protein, and 42.38 respectively. Activity of CA was determined by measuring "CO₂-hydratase activity". Purity control was checked by SDS-PAGE. In vitro inhibitory effect of Cu²⁺, Ag⁺, Cd²⁺, Ni²⁺ metal ions, and arsenic (V) oxide were also examined for both isozymes activities. Whereas Cu²⁺, Ag⁺, Cd²⁺, and Ni²⁺ ions showed inhibitory effects on both isozymes, arsenic (V) oxide showed activation effect. IC₅₀ values were calculated by drawing activity %-[I] graphs for metal ions exhibiting inhibitory effects. IC₅₀ values were determined as 3.39, 6.38, 13.52, and 206 μM for CA I isozyme and 6.16, 20.29, 46, and 223 μM for CA II isozyme respectively.

Biomarker responses of Cu-induced toxicity in European seabass Dicentrarchus labrax: Assessing oxidative stress and histopathological alterations

A comprehensive approach to chemical accumulation and biological effects of short-term Cu exposure in juveniles of European seabass (Dicentrarchus labrax) has been achieved. Fish were exposed to 0.01-10mgL^-1 nominal Cu concentrations for 24-96h. Metal concentrations in water and gills, liver, muscle and brain tissues were studied along with oxidative stress biomarkers (superoxide dismutase, catalase, glutathione peroxidase, lipid peroxidation). Induction of oxidative damage was observed in all the organs with differential antioxidant responses; gills appearing as the most sensitive from low environmentally water Cu concentrations as 0.01mgL^-1. Histopathological alterations were also observed in liver and gills, even without a significant Cu accumulation. The results show that the combination of oxidative stress parameters, particularly lipid peroxidation and glutathione peroxidase activities, and histopathological alterations provide a good model fish and reliable early biomarkers for monitoring Cu pollution in seawater and might call for the protection agencies to revise the Cu environmental standards.

Seasonal and spatial variations of heavy metals in two typical Chinese rivers: concentrations, environmental risks, and possible sources

Ten metals were analyzed in samples collected in three seasons (the dry season, the early rainy season, and the late rainy season) from two rivers in China. No observed toxic effect concentrations were used to estimate the risks. The possible sources of the metals in each season, and the dominant source(s) at each site, were assessed using principal components analysis. The metal concentrations in the area studied were found, using t-tests, to vary both seasonally and spatially (P = 0.05). The potential risks in different seasons decreased in the order: early rainy season > dry season > late rainy season, and Cd was the dominant contributor to the total risks associated with heavy metal pollution in the two rivers. The high population and industrial site densities in the Taihu basin have had negative influences on the two rivers. The river that is used as a source of drinking water (the Taipu River) had a low average level of risks caused by the metals. Metals accumulated in environmental media were the main possible sources in the dry season, and emissions from mechanical manufacturing enterprises were the main possible sources in the rainy season. The river in the industrial area (the Wusong River) had a moderate level of risk caused by the metals, and the main sources were industrial emissions. The seasonal and spatial distributions of the heavy metals mean that risk prevention and mitigation measures should be targeted taking these variations into account.