In vitro effects of cadmium and mercury on Pacific oyster, Crassostrea gigas (Thunberg), haemocytes

Abstract

In the past decades, shellfish culture has developed in a significant way around the world. However, culture areas are often subject to recurring anthropic pollution. The recrudescent presence of industrial wastes is a source of heavy metals and results in pollutant transfer towards the aquatic environment in estuarine areas. Because of their mode of life, bivalves, including mussels and oysters, are suggested as ideal indicator organisms. The development of techniques allowing the analysis of the effects of pollutants on bivalve biology may lead to the monitoring of pollutant transfer in estuarine areas. In this context, the effects of cadmium and mercury on defence mechanisms were analysed in Pacific oysters, Crassostrea gigas. Pollutant effects were tested in vitro on oyster haemocytes. Cell viability and enzymatic activities (esterase, peroxidase, aminopeptidase, phagocytosis activities) were monitored by flow cytometry. Enzymatic phenoloxidase-like activity was also evaluated by spectrophotometry. High pollutant concentrations were used in order to detect the acute effect and to approach real pollutant concentrations existing in animal tissues. Cadmium induced no effect on oyster haemocytes under the tested conditions. On the contrary, mercury caused a significant haemocyte mortality after a 24 h in vitro incubation. Aminopeptidase positive cell percentage was enhanced by the pollutant, and phenoloxidase-like activity was inhibited. These in vitro results show that mercury may be expected to have an impact on bivalve immune functions in contaminated areas.

Metabolic Effects in the BivalvePerna pernaandMytilus galloprovincialis: Impact on the Environment due to Contamination by Copper

“…Copper is one of the agents involved in the oxidative stress [2,24] by the formation of ROS [25,26]; the exposure of marine mollusks to this metal induces lipid peroxidation [27]. Against these hazards, mussels, particularly the species Perna perna and Mytilus galloprovincialis, have developed enzymatic antioxidant defense mechanisms such as super oxide dismutase (SOD, EC 1.15.1.1) or CAT (EC 1.11.1.6) [7,[28][29][30][31].…”

Physiological, Immunological, Genotoxic and Histopathological Biomarker Responses of Molluscs to Heavy Metal and Water-Quality Parameter Exposures: A Critical Review

“…They reported that both metals caused high levels of hemocyte apoptosis, necrosis and mortality after a 24 h in vitro incubation at certain concentrations ranging from 10-1000 µmol L (phenoloxidase, reactive oxygen species generation, cyclooxygenase, COX, activity, cell viability, cell-adherence to polystyrene microwells, phagocytosis) of the species. In a similar work by Gagnaire et al [57], by exposing haemocytes collected from Crassostrea gigas, they found no significant influence on the haemocyte of cadmium concentrations ranging from 3 × 10 -11 M to 3 × 10 -4 M but on exposure to 2 × 10 -4 M of mercury, mass mortality (80%) was recorded at 4-24 h assay. Choi et al [59] documented the effects of cadmium doses and duration on the heat shock protein 90 (HSP90) messenger RNA, mRNA, glutamate pyruvate transaminase, GPT, and glutamate oxaloacetate transaminase, GOT, in the gills, digestive glands and haemolymph of pacific oysters, Crassostrea gigas.…”

“…They observed that at high concentrations (10 -6 -10 -4 M) of mercuric chloride, silver nitrate, Zinc and Cadmium exposures, could result in reduced or impaired haemocyte phagocytic activity and cell viability. Gagnaire et al and Sokolova et al [57,58] investigated the adverse effects of cadmium, Cd and mercury, Hg, exposures on the defence mechanisms of Pacific oysters, Crassostrea gigas. They reported that both metals caused high levels of hemocyte apoptosis, necrosis and mortality after a 24 h in vitro incubation at certain concentrations ranging from 10-1000 µmol L (phenoloxidase, reactive oxygen species generation, cyclooxygenase, COX, activity, cell viability, cell-adherence to polystyrene microwells, phagocytosis) of the species.…”

Bioacumulação de metais pesados em moluscos bivalves: aspectos evolutivos e ecológicos a serem considerados para a biomonitoração de ambientes marinhos

“…A concentração de metal observada em uma amostra de hemolinfa pode apresentar correlação significativa e positiva com a da brânquia e a do hepatopâncreas, porém em valores 10 a 20 vezes inferiores (Cherkasov et al, 2007). O aumento no número total de hemócitos, bem como a mudança nas proporções dos tipos celulares (granulócitos e hialinos), já foi relacionado com o efeito à exposição por metal em bivalves (Pipe et al, 1999;Gagnairea et al, 2004).…”