Transcriptomic responses predict the toxic effect of parental co-exposure to dibutyl phthalate and diisobutyl phthalate on the early development of zebrafish offspring.

Dibutyl phthalate (DBP) and diisobutyl phthalate (DiBP) have been reported to exhibit reproductive toxicity in vertebrates. However, the combined effect of DBP and DiBP on offspring of exposed parents remains unclear, especially for aquatic organisms such as fish. The aims of this study were to assess the effects of parental co-exposure to DBP and DiBP on early development of zebrafish offspring, and to explore the potential molecular mechanisms involved. The early developmental indicators and transcriptomic profiles of F1 larvae were examined after parental exposure to DBP, DiBP and their mixtures (Mix) for 30 days. Results showed that parental exposure to DBP and DiBP, alone or in combination, resulted in increased hatchability at 48 hpf and heart rate at 96 hpf, and increased the prevalence of malformations and mortality in F1 larvae. Generalized linear model (GLM) suggested an antagonistic interactive effect between DBP and DiBP on mortality and malformations of F1 larvae. The transcriptomic analysis revealed that the molecular mechanisms of parental co-exposure were different from those of either chemical alone. Disruption of molecular functions involved unfolded protein binding, E-box binding and photoreceptor activity in F1 larvae. These findings provide initial insights in the potential mechanism of action of parental co-exposure to DBP and DiBP.