Exposure to microplastics affects fatty acid composition in the Japanese quail depending on sex and particle size.

Plastic ingestion in birds is a widespread phenomenon of increasing concern. However, little is known about how exposure to microplastics (MP) affects the health of birds. In other organisms, MP exposure alters lipid metabolism and composition. If also true in birds, this could affect their fitness, especially since birds heavily rely on lipids during migration and egg production. Therefore, the aim of this study was to determine if ingestion of MP (polypropylene and polyethylene collected in nature) in two size ranges, large (3 mm) and small (<125 µm), affects lipid metabolism in the Japanese quail (Coturnix japonica). We orally exposed 55 one-week-old quail during 5 weeks to a total of 600 mg of MP in sizes of either large, small, or a mixture of both. After the exposure period, females fed small MP had higher liver masses compared to control females (on average ± SD, 8.95 ± 2.3 g vs. 6.34 ± 1.0 g), while liver lipid content did not differ in either males or females. The levels of monounsaturated fatty acids were lower in females exposed to large MP and the mixture of both MP sizes compared to controls. Females exposed to MP also had different levels of oleic- (18:1) and palmitoleic (16:1) acid compared to controls dependent on MP size. Exposure to small MP increased levels of palmitic- (16:0) and palmitoleic (16:1) acid in both males and females suggesting a possible increase in de novo fatty acid synthesis. Taken together, our results point towards a sex-specific sensitivity to MP as well as size-dependent MP effects on lipid metabolism in birds. Disruption of fatty acid composition could affect important life stages in female birds, such as migration and egg-laying. We stress the importance of further research focused on determining the mechanisms of action of MP on lipid metabolism.

Chemoproteomic Profiling of 8-Oxoguanosine-Sensitive RNA-Protein Interactions.

Cellular nucleic acids are subject to assault by endogenous and exogenous agents that can perturb the flow of genetic information. Oxidative stress leads to the accumulation of 8-oxoguanine (8OG) in DNA and RNA. 8OG lesions on mRNA negatively impact translation, but their effect on global RNA-protein interactions is largely unknown. Here, we apply an RNA chemical proteomics approach to investigate the effect of 8OG on RNA-protein binding. We find proteins that bind preferentially to 8OG-modified RNA, including IGF2BP1-3 and hnRNPD, and proteins that are repelled by 8OG such as RBM4. We characterize these interactions using biochemical and biophysical assays to quantify the effect of 8OG on binding and show that a single 8OG abolishes the binding of RBM4 to its preferred CGG-containing substrate. Taken together, our work establishes the molecular consequences of 8OG on cellular RNA-protein binding and provides a framework for interrogating the role of RNA oxidation in biological systems.

Microplastic Ingestion Induces Size-Specific Effects in Japanese Quail.

Plastic pollution can pose a threat to birds. Yet, little is known about the sublethal effects of ingested microplastics (MP), and the effects of MP < 1 mm in birds remain unknown. This study therefore aimed at evaluating the toxicity of environmentally relevant polypropylene and polyethylene particles collected in the Norwegian coast in growing Japanese quail (Coturnix japonica). Birds were orally exposed to 600 mg MP over 5 weeks, covering small (<125 µm) and large (3 mm) MP, both separately and in a mixture. We evaluated multiple sublethal endpoints in quail, including oxidative stress, cytokine levels, blood-biochemical parameters, and reproductive hormones in blood, as well as body mass. Exposure to small MP significantly induced the activities of the antioxidant enzymes catalase, glutathione-S-transferase, and glutathione peroxidase. Exposure to large MP increased the levels of aspartate aminotransferase (liver parameter) and decreased 17ß-estradiol levels in females. Body mass was not directly affected by MP ingestion; however, quail exposed to small MP and a mixture of large and small MP had a different growth rate compared to control quail. Our study used similar levels of MP as ingested by wild birds and demonstrated size-dependent effects of MP that can result in sublethal effects in avifauna.