Evaluation of a transgenic tg(Hspa8b: GFP) Nile tilapia for monitoring of stress and anti-stress effects of the influence of temperature and vibration

Abstract

During the cultivation and transportation process, fish are often exposed to many types of stressors such as heat or cold shock, vibration, etc. Stress may cause diverse stress-related health problems such as endocrine disruption, slow growth, immune dysfunction and even produce high mortality. Various anti-stress agents have been developed to alleviate stress. However, the deficiency of stress related animal models limited the development of anti-stress agents. Therefore, it is very necessary to establish an animal model for monitoring of stress in fish species. In this study, we generated a transgenic Nile tilapia (Oreochromis niloticus) line Tg(Hspa8b: GFP) with a Hspa8b promoter-driven Green Fluorescence Protein (GFP) expression. Next, we validated the efficiency and sensitivity of Tg(Hspa8b: GFP) model by monitoring the effects of stresses including heat shock, cold shock and vibration on GFP expression. The results showed the ubiquitous GFP expression was inducible in all examined tissues, including gill, brain, eye, heart, caudal fin, intestine and muscle of Tg(Hspa8b: GFP) transgenic fish under stressful conditions. The elevated green fluorescent signals were even found in the gill of Tg(Hspa8b: GFP) transgenic fish as early as 0.5 h after exposure to stress, and the strong green fluorescence can be continuously observed from 0.5 to 12 h after stress. There was a strong positive correlation between the GFP expression and the endogenous Hspa8b mRNA expression, which indicates that the Tg(Hspa8b: GFP) transgenic Nile tilapia can be used as an effective model to monitor stress in vivo. Furthermore, we evaluated anti-stress protective effects of anti-stress agents using Tg(Hspa8b: GFP) transgenic fish and identified the optimum anti-stress agent under different stressful conditions. We found that vitamin C and eugenol were the two preferred anti-stress agents to alleviate heat stress. MS-222 and tea polyphenols possesses the most significant anti-stress activity under cold stress. MS-222 and vitamin C were the two preferred anti-stress agents to alleviate vibration stress. This report would suggest new avenues for monitoring of fish stress responses in vivo and evaluating the anti-stress effects of related agents.