Microplastics containing plasticizers affect chicken reproduction via disturbing ovary DNA homologous recombination activity

Microplastics (MPs) alone or carrying organic contaminants (OCs) have been proven to exhibit a wide range of toxic effects on aquatic animals. Nevertheless, the impacts and mechanisms for co-exposure to MPs and OCs on vertebrate animals remain obscure. This study investigated the impact of clean and phthalate esters (PAEs)-spiked MPs on chicken by observing the egg-laying behavior, analyzing the levels of PAEs and their metabolites in eggs, as well as exploring the gene expression in ovaries. Results showed that 16 eggs were collected from the 10 %-spiked MPs group during depuration period though no eggs production during exposure period. The finding suggested that the impaired ovarian functions and egg-laying behavior gradually improved once the exposure ceased. Concurrent chemical analysis indicated that the damage extent to ovarian development was highly correlated with the accumulation and elimination of PAEs and their metabolites. The depuration period led to a 97.5 % reduction in di-(2-ethylhexyl) phthalate concentrations in ovarian yolk relative to the exposure period. Additionally, parent PAEs were more inclined to accumulate in egg yolk, while their metabolites were mainly enriched in egg white. Furthermore, the transcriptomic analysis revealed that PAEs-spiked MPs induced significant gene expression changes and activated DNA homologous recombination in ovaries (26 up-regulated and 3 down-regulated genes), leading to delayed ovarian development. Overall, this study provides new insights into the reproductive toxicity and corresponding molecular mechanisms of MPs and PAEs, alarming the potential risks to animal health and human food safety from these pollutants in poultry.