Effects of supplemental ultraviolet light on growth, oxidative stress responses, and apoptosis-related gene expression of the shrimp Litopenaeus vannamei

Abstract

Ultraviolet light is an important part of the natural spectrum and has specific ecological functions, but its impact on the growth and physiology of shrimps remains unclear. This study was conducted to evaluate the effect of supplemental ultraviolet (UV) A and B light on growth, oxidative stress responses, and apoptosis-related gene expression of the shrimp Litopenaeus vannamei. Shrimps (initial weight 1.98 ± 0.25 g) were maintained in four lighting environments (full spectrum, peak at 400–800 nm; full spectrum + UVA, peak at 355 nm; full spectrum + UVB, peak at 310 nm; and dark) in triplicate tanks for 60 days, and the photoperiod is 12 L: 12 D for full spectrum while 2 h/d for UV. At the end of the trial, final mean weight, percent weight gain, and specific growth rate in shrimps were significantly highest in the full spectrum + UVA group (P <.05), and followed by the full spectrum + UVB group. Feed conversion ratio of shrimps in the full spectrum + UVA group was significantly lower than in the other groups (P < .05), and the values from high to low were as follows: dark, full spectrum, full spectrum + UVB, full spectrum + UVA (P < .05). Mortality rates were significantly higher in the dark (53.89%) and full spectrum (29.44%) groups than in the other groups (P < .05). The activities of superoxide dismutase, glutathione peroxidase, and catalase of shrimps in the full spectrum + UVA group were significantly higher than values in the full spectrum + UVB group, and both of their values were significantly higher than those of the other groups (P < .05). The activity of alkaline phosphatase did not differ significantly between the full spectrum + UVA and full spectrum + UVB groups, but their values were significantly higher than those in the full spectrum and dark groups (P < .05). In the dark group, the transcription levels of Bcl2, p53, cytochrome c, caspase 3, caspase 8 and caspase 10 in the eyestalk and hepatopancreas were higher than in the other groups (P < .05). The results of this study show that supplementation with UV light affected shrimp growth and oxidative stress physiology and that the full spectrum + UVA environment was most suitable for the growth of L. vannamei.