Temporal control of responses to chemically induced oxidative stress in the gill mucosa of Atlantic salmon (Salmo salar)

• Published in: Journal of Photochemistry and Photobiology B: Biology
• Main Authors: Lazado, Carlo C., Voldvik, Vibeke
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2020
• Subjects: Paa; Atlantic salmon; Salmo salar
• Online Access: https://hdl.handle.net/11250/2678283; https://doi.org/10.1016/j.jphotobiol.2020.111851

Molecular clocks are known to mediate cellular responses during oxidative stress. This important interplay is less understood in fish, particularly at mucosal surfaces. Here we report the coordinated modulation of the molecular clocks and antioxidant defence following chemically induced oxidative stress in the gill mucosa of Atlantic salmon (Salmo salar). A short-term gill explant (GE) culture was used as a model in a series of experiments aiming to demonstrate how photoperiod during culture, levels of environmental reactive oxygen species (ROS), time of oxidative stress induction, and the daily light-dark cycle affect the expression of molecular clocks and antioxidant genes in the gills. Photoperiod (either 12 light:12 dark cycle, LD or 0 light:24 dark cycle, DD) during explant culture affected the transcription of two clock genes, circadian locomotor output cycles kaput (clk) and period 1 (per1), as well as one antioxidant gene, glutathione peroxidase (gpx). When the GEs were exposed to two ROS-generating oxidants (i.e., peracetic acid, PAA and hydrogen peroxide, H2O2), photoperiod condition was demonstrated to have a significant impact on the transcription of the core genes. PAA significantly downregulated the expression of reverb alpha (reverbα) under LD, while per1 and per2 expression were significantly upregulated under DD. Nevertheless, there was no distinct pattern in the oxidant-induced expression of clock genes. On the other hand, photoperiod was shown to influence the antioxidant defence under increased ROS level, where significant transcriptional upregulation was a hallmark response under LD. Interestingly, no changes were identified under DD. Induction of oxidative stress either at ZT2 (2 h after lights on) or at ZT14 (2 h after lights off) revealed striking differences that highlighted the temporal sensitivity of the oxidative defence repertoire. Per1 was significantly modulated following time-dependent induction of oxidative stress amongst the clock genes. Inducing oxidative stress at ZT2 resulted ...