Application of Micronucleus Test in African Toad as Biomarker of Genotoxic and Cytotoxic Assessment of Contaminants in the African Environment

Xenobiotics are constantly discharged into the environment due to unprecedented anthropogenic activities. Xenobiotics including radiation, chemical contaminants, parasites / pathogens, toxic metals, and climate change may work individually or in combinations to cause adverse health effects on amphibians. These xenobiotics are stressors that can either induce sublethal toxicity (morbidity) or cause death (mortality) on exposed amphibians. In this chapter, micronucleus biomarker measured in African toads is used to assessed the genotoxicity and cytotoxicity induced by xenobiotics. Also, the role of oxidative stress parameters assessed in African toads which may enhance genotoxicity and cytotoxicity was reviewed. Contaminants in the African environment induced a significant increase in the frequencies of micronucleus and abnormal nuclear formation in the examined African toads, an indication of genotoxicity and cytotoxicity. DNA damage caused by these contaminants may exacerbate pathophysiological disorder, abnormal inflammation, genetic disease disorder, reproductory disorders, and deformed morphology. These abnormalities basically debilitate affected toads and may cause their death. This phenomenon describes threat to amphibian well-being and are contributors of decline in population. However, more studies are required to establish adequate understanding of the causal effects between contaminants in African environment and anuran population decline.