Microsatellite Instability Assay as a Potential Approach to Evaluate Genotoxicity: Lead Exposure in a Nestling Passerine Bird at the Stage of Intensive Erythropoiesis

SIMPLE SUMMARY: This is the first case of an experimental study with a novel approach to analyze microsatellite instability (MSI) as a detection tool for genetic alterations in a wild population of birds, in this case for great tits (Parus major) being exposed to lead compounds. Although this preliminary study did not find any MSI in the analyzed microsatellite markers, it contributes to the examination of this molecular technique as a potentially applicable bioindication tool in ecotoxicological bird studies. We believe that certain issues should be considered in finding an explanation for our result. First, the exposure to lead was too low to induce genetic alterations. Second, the panel of microsatellite markers studied may have been unsusceptible to lead genotoxicity. Third, the time interval (5 days) between lead exposure and blood sampling for genetic analyses were too short to trigger genotoxicity. Further analyzes are needed to verify these findings and to evaluate the scope of application of the MSI analysis in wild bird population studies. ABSTRACT: Although many avian studies have investigated the toxic effects of lead on important biochemical and physiological processes, organ and system function, and behavior, studies evaluating the specific genotoxic effects of exposure to lead are scarce. Nowadays, rapid technological advances can provide new molecular techniques in this regard. In this study, as a novel approach in bird studies, we used a panel of ten microsatellite loci to investigate the microsatellite instability (MSI) in response to experimental lead intoxication in a common hole-nesting species, the great tit Parus major. For this purpose, an experiment based on an intentional single supplementation of a lead (II) acetate trihydrate compound was conducted, with the use of two different doses, applied to randomly chosen great tit nestlings from randomly selected broods, being at the stage of intensive erythropoiesis. Although this preliminary study did not find any MSI in the seven microsatellite markers retained for the final comparison, it contributes to the examination of this molecular technique in field conditions as being potentially applicable in ecotoxicological bird studies. We believe that certain issues should be considered in finding an explanation for our result. First, the single doses of lead used in this study may have been too weak to induce genetic instability. Second, the panel of microsatellite markers studied may have been unsusceptible to lead genotoxicity in general. Third, the relatively short time interval (5 days) between the experimental procedure (lead exposure) and the sampling of post-exposure material (blood) for genetic analyses could have limited the effect of lead genotoxicity. Further analyzes are needed to verify these findings and to evaluate the scope of application of the MSI analysis in wild bird population studies.