The dynamics of protein and metal metabolism in acclimated and Cd-exposed freshwater crabs (Potamonautes warreni).

Climatic and man-made impacts induced dynamic molecular responses in the South African freshwater crab, Potamonautes warreni. Adult crabs exhibited MT-like protein, binding Cd (0.02micromolg(-1) wet mass+/-0.02), Cu (0.326micromolg(-1) wet mass+/-0.15), and Zn (0.534micromolg(-1) wet mass+/-0.20). The native protein binding Cd, Cu, and Zn showed a respective molecular mass (M) of 9.10kDa+/-1.74, 8.95kDa+/-1.66, and 9.32kDa+/-0.93. With exposure to 0.2mgCd(2+)l(-1) for up to 21 days in 50% of these crabs approximately 90% of Cd was bound to the MT-like protein component (8.54kDa+/-1.64), coinciding with a Zn-bound MT-like component (8.2kDa+/-1.54). Less than 10% were bound in the high M protein component, suggesting a protective function of the protein. In the remaining crabs metals were bound to protein (6.8kDa) with a predominant Cu-binding component.

Interactive cellular and physiological responses of the freshwater crab Potamonautes warreni to cadmium and microbial gill infestations.

Cellular and physiological responses of the freshwater crab, Potamonautes warreni, to cadmium and microbial gill infestations were investigated. Infested crabs were collected from the Mooi River, at Noordbrug, Northwest Province, South Africa in the autumn of 1995 and exposed to 0.2mg Cd(2+)L(-1) or kept unexposed under constant laboratory conditions for 7, 14 and 21 days at 24 degrees C. Cellular lesions with microbial gill infestations were persistent over 21 days and showed a similar species diversity and density as recorded in the previous summer [Schuwerack et al., 2001a. Pathological and physiological changes in the South African freshwater crab, P. warreni Calman induced by microbial gill infestations. J. Invertebrate Pathol. 77(4), 259-269]. With Cd exposure the microbial community disappeared and crabs showed a higher mean but wider range in ammonia excretion and lower mean O:N ratio after 7 days. After 14 days exposure to Cd, time- and stressor-specific cellular and physiological responses included degeneration of oxygen and gas exchange gill tissues and a mean reduced growth rate, ion exchange, a significantly reduced O:N ratio (P

Inflammatory interactions in fish exposed to pollutants and parasites: a role for apoptosis and C reactive protein.

Although previous studies have highlighted the inflammatory responses of fish infected with parasites and exposed to pollutants, very little is known about how these two stressors interact within the fish. In this review, which also contains original data, the effect of these two parameters on the fish inflammatory response is assessed and, in particular, the role of apoptosis and the acute phase protein, C reactive protein, is evaluated. In Cyprinus carpio exposed to 0.5 mg NH4+ l(-1) or 0.1 mg Cd2+ l(-1) and experimentally infected with the blood fluke, Sanguinicola inermis, the pollutant type and the order in which the fish experiences the parasite and toxicant, significantly affects the ultrastructural appearance and cellular content of the pronephros and thymus. This is reflected in the intensity of infection where the pollutant appears to have less effect on an established infection. Both stressors, pollutant and infection, may mediate their effects via the endocrine system. Studies have revealed that cortisol at 100 ng ml(-1) is able to induce apoptosis in pronephric cells of carp and that an increase in apoptosis is associated with an increase in phagocytosis in this immune organ. In addition, C reactive protein, which is used as a biomarker of the inflammatory response in humans and other mammals, is evaluated as a possible indicator of physiological states in fish exposed to pathogens and pollutants.

Cadmium-induced cellular and immunological responses in Cyprinus carpio infected with the blood parasite, Sanguinicola inermis.

Little is known about immune responses in teleosts as linked to the aetiology of pollutants and parasitic diseases and in particular their combined effects on the host. Cadmium(Cd)-mediated immunological responses in the thymus and pronephros of juvenile carp (Cyprinus carpio), experimentally infected with the blood parasite, Sanguinicola inermis (Trematoda: Sanguinicolidae) for 30 days followed by an exposure to 0.1 mg Cd2+ l(-1) for 48 or 168 h were investigated. Differential organ-specific changes occurred in both organs examined. In carp exposed to Cd, intracelluar spaces, vacuolation in the eosinophils, dissociation of cell membranes together with the formation of concentric whorls occurred. The thymus of infected carp exposed to Cd had a granular cytosol which contained vesicles with electron-dense inclusions, swollen mitochondria with distended cristae and condensed nuclei in the erythrocytes. Cell counts on the two organs revealed a differential response to cadmium exposure in S. inermis infected carp compared to control infected fish. A significant increase in the neutrophil, eosinophil and thrombocyte components occurred in the thymus in contrast to a significant decrease in pronephric neutrophils. In addition, there was a differential blastogenesis response in infected and Cd-exposed infected carp fry exposed to cercarial antigens and the mitogens, concanavalin A and pokeweed mitogen.