Expression of Hsp70, Igf1, and Three Oxidative Stress Biomarkers in Response to Handling and Salt Treatment at Different Water Temperatures in Yellow Perch, Perca flavescens.

Nour Eissa,Han-Ping Wang,Zhi-Gang Shen,Hong Yao,Elsayed N Abou-Elgheit,Adel A Shaheen

doi:10.3389/fphys.2017.00683

Abstract

Stress is a major factor that causes diseases and mortality in the aquaculture industry. The goal was to analyze the expression of stress-related biomarkers in response to different stressors in yellow perch, which is an important aquaculture candidate in North America and highly sensitive to handling in captivity. Three fish groups were established, each having four replicates, and subjected to water temperatures of 14, 20, and 26°C and acute handling stress was performed followed by a salt treatment for 144h at a salinity of 5 ppt. Serum and hepatic mRNA levels of heat shock protein (hsp70), insulin-like growth factor 1 (Igf1), glutathione peroxidase (Gpx), superoxide dismutase 1 (Sod1), and glutathione reductase (Gsr) were quantified at seven times interval over 144 h using ELISA and RT-qPCR. Handling stress caused a significant down-regulation in Hsp70, Gpx, Sod1, and Gsr at a water temperature of 20°C compared to 14 and 26°C. Igf1 was significantly upregulated at 20°C and down-regulated at 14 and 26°C. Salt treatment had a transient reverse effect on the targeted biomarkers in all groups at 72 h, then caused an upregulation after 144 h, compared to the control groups. The data showed a negative strong regulatory linear relationship between igf1 with hsp70 and anti-oxidative gene expressions. These findings could provide valuable new insights into the stress responses that affect fish health and could be used to monitor the stress.

Highlights

The study of the candidate genes of the stress responses could be unique signatures or imprints of specific stressors and determine early signs of stressors
Posthandling, serum, and hepatic protein level of Hsp70 and hepatic mRNA level of hsp70 up-regulated at water temperature 14 and 26◦C while significantly down-regulated at 20◦C (Figures 2A, 3A, 4A)
The present study revealed that physiological stress induced by handling stress and salt treatment at different temperatures can alter the expression of particular markers related to stress and growth in yellow perch and that a relationship may exist between Hsp70, Oxidative stress (GPx, SOD, and Gsr), and growth-related marker (Igf1) expression

Summary

Introduction

The study of the candidate genes of the stress responses could be unique signatures or imprints of specific stressors and determine early signs of stressors. Aquaculture and fisheries industries have several unavoidable stressors, such as handling, transportation, temperature, crowding, salinity, hyperoxia, and hypoxia that result in the stress responses of fish (Eissa and Wang, 2016). Homeostatic adjustments of plasma and whole body stress hormones and metabolites in response to various stressors have been well studied, the underlying transcriptional regulation and functional genomics of stress responses can provide a better understanding of stress pathophysiology (Prunet et al, 2008; Aluru and Vijayan, 2009; Eissa and Wang, 2016). In our recent study on yellow perch stress response, the stress protocol under different water temperatures showed a fluctuant elevation in plasma cortisol concentration (Eissa and Wang, 2013). Identifying stress biomarkers using genomic tools is an essential aspect for minimizing fish disease and mortality in the aquaculture industry and fisheries stock enhancement

Methods

Results

Conclusion