Combined exposure of Japanese quails to cyanotoxins, Newcastle virus and lead: Metallothioneins, accumulation and distribution of toxins

Wild birds can be continually exposed to many anthropogenic and natural stressors in their habitats. The objectives of this study were testing of hypothesis that heavy metals, cyanotoxins and a immunological challenge combine to enhance effects of avian toxicity. We examined metallothionein levels, a family of cystein-rich proteins that reduce the toxicity of various metals and scavenge free radicals generated in oxidative stress. The study employed 30day single and combined exposures of Japanese quails (Coturnix coturnix japonica) to cyanobacterial biomass, lead and live Newcastle vaccination strain. A total of 40 birds were divided on a random basis into 8 groups of 5 individuals, i.e. C = control group, B = cyanobacterial biomass-exposed group, V=Newcastlevaccinated group, Pb= lead-exposed group and double (BPb, BV, PbV) and triple (BPbV) combinations. After the exposure period, birds were sacrificed and selected organs (brain, liver, kidney, muscle) were collected for metallothionein measurement. Metallothioneins were determined using the differential pulse voltammetry Brdicka reaction. Statistically significant differences (p<0.05) were observed between the value of MTs in the liver and muscle in subjects from groups B, Pb, BPb, BV, PbV, BPbV versus control group (C). The lead-exposed groups (Pb, BPb, PbV, BPbV) had statistically significant (p<0.05) less body mass than non lead-exposed groups (C, B, V, BV). In conclusion, this study provides data on responses of metallothioneins in birds exposed tomultiple stressors. The notion that metal-binding by MTs are protective of cellular function is supported by this study.