Evaluating the biological impact of polyhydroxyalkanoates (PHAs) on developmental and exploratory profile of zebrafish larvae

In this study, we employed zebrafish as an animal model to evaluate the biological effect of polyhydroxyalkanoates (PHAs) on early development via morphological, physiological, and behavioural analyses. Developmental results indicated no obvious adverse effects of PHAs on the development of zebrafish embryos and larvae, except the occurrence of krox20 expression fluctuation. Furthermore, standard and colour-enriched open field tests were conducted to assess the natural colour preference/avoidance behaviour of zebrafish larvae as well as the effect of PHA concentration on patterns of exploratory behaviour and natural colour preference/avoidance. The behavioural results were as follows: (1) compared with un-injected larvae, PHA-injected larvae displayed enhanced exploratory behaviour with decreased thigmotaxis (central avoidance) in the open field test and increased thigmotaxis (central avoidance) in the colour-enriched open field test. (2) PHA injection attenuated anxiety-like behaviour by decreasing latency prior to exploration. (3) PHAs increased the preference for blue, red and black colours. In conclusion, PHAs have a concentration-dependent effect on strengthening exploratory behaviour, lessening anxious behaviour and altering the colour preference/avoidance patterns of larval zebrafish. These results suggest that PHAs have a potential effect on the behaviour of zebrafish.