Anatoxin-a induces apoptosis of leukocytes and decreases the proliferative ability of lymphocytes of common carp (Cyprinus carpio L.) in vitro

Cyanobacteria (Cyanophyta, Cyanoprocaryota, Cyanobacteria) (blue-green algae) are procaryotic phototrophic microorganisms playing an important ecological role in the freshwater and marine environment as primary producers. However, as a consequence of water eutrophication observed in many reservoirs in different parts of the world, these microorganisms form massive scums, known as water blooms, releasing cyanotoxins hazardous to fish and other aquatic organisms. Cyanotoxins are cyanobacterial secondary metabolites of various chemical structures harmful to humans, terrestial and aquatic animals such as fish. The most abundant cyanotoxins are microcystins and hepatotoxins inducing toxic changes in fish liver, kidney, gills, digestive tract and immune system. Very little is known on the effects of alkaloid neurotoxic anatoxin-a on fish and their immunity. The aim of this study was to assess the in vitro influence of anatoxin-a on immune cells isolated from the common carp (Cyprinus carpio L.). The leukocyte intracellular level of ATP was reduced only at the highest concentration of anatoxin-a. Apoptotic and necrotic leukocytes were observed at the lower and the highest concentrations of anatoxin-a, respectively. Elevated activity of caspases 3/7 after 2 hours and a concentration-dependent decrease in the proliferative ability of T and B lymphocytes was also observed. The results suggest that anatoxin-a could be a possible immunotoxic agent in the aquatic environment and may increase the susceptibility of fish to infectious and neoplastic diseases. Therefore, constant monitoring of anatoxin-a and its producers in lakes and fish ponds should be performed

A Qualitative Meta-Analysis Reveals Consistent Effects of Atrazine on Freshwater Fish and Amphibians

OBJECTIVE: The biological effects of the herbicide atrazine on freshwater vertebrates are highly controversial. In an effort to resolve the controversy, we conducted a qualitative meta-analysis on the effects of ecologically relevant atrazine concentrations on amphibian and fish survival, behavior, metamorphic traits, infections, and immune, endocrine, and reproductive systems. DATA SOURCES: We used published, peer-reviewed research and applied strict quality criteria for inclusion of studies in the meta-analysis. DATA SYNTHESIS: We found little evidence that atrazine consistently caused direct mortality of fish or amphibians, but we found evidence that it can have indirect and sublethal effects. The relationship between atrazine concentration and timing of amphibian metamorphosis was regularly nonmonotonic, indicating that atrazine can both accelerate and delay metamorphosis. Atrazine reduced size at or near metamorphosis in 15 of 17 studies and 14 of 14 species. Atrazine elevated amphibian and fish activity in 12 of 13 studies, reduced antipredator behaviors in 6 of 7 studies, and reduced olfactory abilities for fish but not for amphibians. Atrazine was associated with a reduction in 33 of 43 immune function end points and with an increase in 13 of 16 infection end points. Atrazine altered at least one aspect of gonadal morphology in 7 of 10 studies and consistently affected gonadal function, altering spermatogenesis in 2 of 2 studies and sex hormone concentrations in 6 of 7 studies. Atrazine did not affect vitellogenin in 5 studies and increased aromatase in only 1 of 6 studies. Effects of atrazine on fish and amphibian reproductive success, sex ratios, gene frequencies, populations, and communities remain uncertain. CONCLUSIONS: Although there is much left to learn about the effects of atrazine, we identified several consistent effects of atrazine that must be weighed against any of its benefits and the costs and benefits of alternatives to atrazine use