Intergenerational toxic effects of parental exposure to bisphenol AF on offspring and epigenetic modulations in zebrafish.

Bisphenol AF (BPAF), an endocrine-disrupting chemical, has been detected in various environmental media because of its wide industrial applications. Meanwhile, substances that are known to be toxic to the reproductive system have been observed to interfere with the development of the offspring following parental exposure. This study was aimed at determining the gender-dependent intergenerational effects of BPAF on offspring development following either paternal or maternal exposure of adult zebrafish to an environmental concentration of BPAF. Four-month-old zebrafish (F0) were exposed to 10 µg/L of BPAF for 28 days, the developmental endpoints of F1 embryos were then tested without further treatment with BPAF. The results show that paternal BPAF exposure decreased the hatching rate, increased mortality, and shortened the body lengths of F1 larval offspring. In addition, it changed DNA and m6A RNA methylation gene expression levels in F0 testes and F1 larvae. Although maternal exposure increased mortality and enhanced antioxidant enzyme activities in F1 larvae, only DNA methylation gene expression was altered in F0 ovaries and F1 larvae. In addition, a short term BPAF exposure of zebrafish embryos from 4 h post-fertilization (hpf) until 120 hpf similarly impaired the early development of the larvae but only at a level relatively higher than 10 µg/L; and DNA and RNA methylation gene expression was regulated to some extent in BPAF exposure groups. Overall, our results indicate the gender-specific effects of BPAF on offspring development and epigenetic modulations, suggesting a relatively high susceptibility within the exposure window during gametogenesis and early embryonic developmental stages to environmental chemicals.

Toxic effects of different-sized graphene oxide particles on zebrafish embryonic development.

Graphene oxide (GO) has broad application potential in many fields, such as biomedicine and energy. Due to the wide-ranging GO applications, its entry into the environment is inevitable along with the potential for ecological and environmental risks. In the present study, we systematically investigated the dose-dependent effects of three different-sized GO particles (50-200 nm, <500 nm, and >500 nm) on zebrafish during the very early developmental stages (4-124 h post-fertilization). The results showed that GOs could accumulate in the eyes, heart, yolk sac, and blood vessels of fish larvae. Consequently, their effects on multiple toxic endpoints were observed, including delayed hatching times, shortened body lengths, alterations in heart rate and blood flow, changes in swimming activity and responses to photoperiod stimulation, and the enhanced activity of total superoxide dismutase, inducible nitric oxide synthase, acetylcholinesterase, caspase-3, and induction of apoptosis-related gene expression. As a result, the occurrence of oxidative stress and the induction of apoptosis are suggested in fish larvae exposed to all three different-sized GO particles. In addition, our results highlight the impacts of waterborne-GO exposure on zebrafish during early development, which were not merely dependent on GO concentration but also on the associated GO sizes. This study hereby provides a basis for the potential ecological and health risks of GO exposure.