Homosalate and UVB co-exposure triggers metabolic disruption and impairs energy homeostasis and antioxidant defenses in early life stages of yellowstripe goby (Mugilogobius chulae).

Abstract

Homosalate (HMS), an organic UV filter, is a widespread aquatic contaminant that bioaccumulates in marine organisms, but its combined toxicity with UVB radiation remains unclear. In this study, we investigated the embryonic responses of the marine fish Mugilogobius chulae to HMS and UVB-HMS co-exposure across an environmentally relevant (3 μg L-1) and a sub-lethal threshold concentration (300 μg L-1). Multi-scale toxicity endpoints-spanning molecular (ATP levels and ATPase activity), physiological indices (oxidative stress and lipid metabolism markers), and organismal phenotypes (hatching and early-life phenotypes)-were integrated with untargeted metabolomics to evaluate the ecological risks of HMS. The results showed that single HMS exposure altered energy balance and induced endocrine disruption. UVB radiation markedly enhanced HMS-induced developmental toxicity, leading to impaired hatching. Significant interaction terms confirmed the potentiation by UVB of elevated heart rate, altered spontaneous movement, and phenotypic lipid accumulation under HMS exposure. Physiological responses exhibited divergent patterns across exposure levels, with low-dose co-exposure inducing prominent energy disruption and oxidative stress. Under environmentally relevant exposure, metabolomic analyses showed that combined UVB-HMS exposure triggered broader metabolic rewiring and pronounced oxidative responses, including altered TCA cycle intermediates, enhanced antioxidant defense, and disturbed lipid metabolism, which corresponded to observable lipid accumulation in larvae. Compared with HMS single exposure, UVB exacerbated disruptions in energy metabolism and further impaired neural signaling. Overall, these findings demonstrate that UVB radiation can potentiate HMS toxicity, providing a scientific foundation for ecological risk assessment under multi-stressor scenarios.