Transcriptomic Analysis Provides Novel Insights into Heat Stress Responses in Sheep.

Zengkui Lu,Qing Li,Lin Ma,Meilin Jin,Liping Zhang,Caihong Wei,Mingxing Chu,Xiaojuan Fei

doi:10.3390/ani9060387

Abstract

Simple SummaryThe general increase in global temperatures has meant that heat stress has become an increasingly significant problem for sheep. This has both direct and indirect impact on their physiological functions, productivity, and health of sheep. Sheep generally live in high-temperature environments; however, the genes and pathways that play regulatory roles in the heat stress responses of sheep remain unclear. In this study, we applied RNA-Seq technology to analyze liver tissues of sheep from heat-stressed and control groups, and screened genes and pathways related to sheep heat stress. This work provides a theoretical foundation for the breeding and production of heat-resistant sheep.With the intensified and large-scale development of sheep husbandry and global warming, sheep heat stress has become an increasingly important issue. However, little is known about the molecular mechanisms related to sheep responses to heat stress. In this study, transcriptomic analysis of liver tissues of sheep in the presence and absence of heat stress was conducted, with the goal of identifying genes and pathways related to regulation when under such stress. After a comparison with the sheep reference genome, 440,226,436 clean reads were obtained from eight libraries. A p-value ≤ 0.05 and fold change ≥ 2 were taken as thresholds for categorizing differentially expressed genes, of which 1137 were identified. The accuracy and reliability of the RNA-Seq results were confirmed by qRT-PCR. The identified differentially expressed genes were significantly associated with 419 GO terms and 51 KEGG pathways, which suggested their participation in biological processes such as response to stress, immunoreaction, and fat metabolism. This study’s results provide a comprehensive overview of sheep heat stress-induced transcriptional expression patterns, laying a foundation for further analysis of the molecular mechanisms of sheep heat stress.

Highlights

Since its foundation in 1988, the Intergovernmental Panel on Climate Change has released five comprehensive climate reports and highlighted the indisputable fact that the world is warming.In the wild, air temperature has a major bearing on the ability of animals to thrive
Temperature-humidity index (THI) was ≥ 26.18, indicating that the sheep were exposed to extremely severe heat stress; in the control group, THI ≤ 11.82, indicating that the sheep experienced no heat stress (Supplementary Figure S1) [14]
Four sheep under heat stress and four without such stress were selected in this study, from which 1,137 differentially expressed genes were screened out using RNA-Seq. quantitative real-time PCR (qRT-PCR) results revealed expression patterns of 10 genes that were identical to those in the RNA-Seq results, proving that the sequencing results were accurate and reliable

Summary

Introduction

Since its foundation in 1988, the Intergovernmental Panel on Climate Change has released five comprehensive climate reports and highlighted the indisputable fact that the world is warming.In the wild, air temperature has a major bearing on the ability of animals to thrive. Animals 2019, 9, 387 manifested by physiological features such as gasping for breath, accelerated respiration, elevated heart rate, rising rectal temperature, increasing in-vivo oxidative metabolism, and water and electrolyte disturbance [4,5,6,7]. Regarding reproduction, it can cause reduced food intake, weight loss, and declining fertility [8,9,10], as well as declining immunity and disease resistance [11,12]. The transcriptome, which has become a powerful tool for analyzing the relationship between genotype and phenotype, has been extensively applied to the analysis of complicated biological events

Objectives

Methods

Results

Discussion

Conclusion