Does Arsenic Contamination Affect DNA Methylation Patterns in a Wild Bird Population? An Experimental Approach

Abstract

Pollutants, such as toxic metals, negatively influence organismal health and performance, even leading to population collapses. Studies in model organisms have shown that epigenetic marks, such as DNA methylation, can be modulated by various environmental factors, including pollutants, influencing gene expression, and various organismal traits. Yet experimental data on the effects of pollution on DNA methylation from wild animal populations are largely lacking. We here experimentally investigated for the first time the effects of early-life exposure to environmentally relevant levels of a key pollutant, arsenic (As), on genome-wide DNA methylation in a wild bird population. We experimentally exposed nestlings of great tits ( Parus major ) to arsenic during their postnatal developmental period (3 to 14 days post-hatching) and compared their erythrocyte DNA methylation levels to those of respective controls. In contrast to predictions, we found no overall hypomethylation in the arsenic group. We found evidence for loci to be differentially methylated between the treatment groups, but for five CpG sites only. Three of the sites were located in gene bodies of zinc finger and BTB domain containing 47 ( ZBTB 47), HIVEP zinc finger 3 ( HIVEP 3), and insulin-like growth factor 2 mRNA binding protein 1 ( IGF 2 BP 1). Further studies are needed to evaluate whether epigenetic dysregulation is a commonly observed phenomenon in polluted populations and what are the consequences for organism functioning and for population dynamics.

Variation in DNA Methylation in Avian Nestlings Is Largely Determined by Genetic Effects

“…DNA methylation is especially prone to changes during early life. In vertebrates, DNA methylation is reported to be affected during early life by temperature ( Sheldon et al 2020 ), the type of rearing environment ( Morán et al 2013 ; Venney et al 2021 ), brood size ( Sheldon et al 2018 ; Sepers et al 2021 ), parental care ( Weaver et al 2004 ), nutrition ( Waterland and Jirtle 2003 ; Sandovici et al 2011 ), and pollutant exposure ( Laine et al 2021 ; Mäkinen et al 2022 ). Thus, methylation marks can either be highly programmed and differ little in state between individuals or be influenced by a combination of genetic and environmental factors that lead to inter- and intraindividual variation in DNA methylation states.…”

Ultra-Performance Liquid Chromatography-Tandem Mass Spectrometry for the Analysis of Complex Compounds in Serum and Its Application in Accurate Detection of Early Arsenic Exposure

“…Many research studies have attempted to reveal the toxicity of arsenic to human, especially trivalent inorganic arsenic. Inorganic arsenic and its compounds were generally considered to be more toxic than organic arsenic. − Modern studies have shown that exposure to inorganic arsenic could lead to DNA damage − and protein denaturation. − Although many research studies aimed at revealing the mechanism of arsenic damage to body, early detection of arsenic exposure at low doses was still difficult. When clinical symptoms of arsenic exposure have occurred, the body has usually already suffered some serious damage.…”

Heavy Metals in Wetland Ecosystem: Investigating Metal Contamination in Waterbirds via Primary Feathers and Its Effect on Population and Diversity

“…Moreover, studies reported that As, Cd, Co, Cr, Cu, Pb, Ni and Zn have remarkable impacts on avian communities; for example, an excessive level of As can damage the DNA in birds [26]. A higher level of Cd in birds can damage their flying mechanisms and lead to poor development of bones [27].…”