Single and Combined Effects of Ultraviolet Radiation and Triclosan During Metamorphosing Solea Senegalensis

Abstract

Ultraviolet radiation (UV) and triclosan (TCS) affect the early development of marine fish; however, the corresponding molecular mechanisms are still not fully understood. Therefore, this work aims to study the effects of the single and combined to these stressors during the thyroid-regulated metamorphosis of the flasfish Solea senegalensis .Sub-lethal exposure (5.89 kJ.m -2 UV and/or 0.546 and 1.090 mg.L -1 TCS) was performed for 48h at the beginning of metamorphosis (13 days after hatching, dah), followed by a period in clean medium until complete metamorphosis (24 dah). Malformations, metamorphosis progression, length, behavior and the expression of thyroid-axis related genes were studied.TCS induced malformations, decreased swimming, and induced metamorphosis acceleration at 15 dah, followed by a significant metamorphosis delay. Such effects were more noticeable in the presence of UV. The down-regulation of five thyroid axis-related genes occurred after the exposure to TCS (15 dah), and after 9 days in clean media, only two genes were still down-regulated. UV exposure increased the effect of TCS by further down-regulating gene expression immediately after the exposure.Since several effects persisted after a period in clean medium, implications of these stressors (mainly TCS) on the ecological performance of the species are suggested.

Keywords: abiotic stress, flatfish, behavior, Metamorphosis, personal care products, thyroid axis