title: Liver transcriptome response to hyperthermic stress in three distinct chicken lines.
abstract: High ambient temperatures cause stress in poultry, especially for broiler lines, which are genetically selected for rapid muscle growth. RNA-seq technology provides powerful insights into environmental response from a highly metabolic tissue, the liver. We investigated the effects of acute (3 h, 35 °C) and chronic (7d of 35 °C for 7 h/d) heat stress on the liver transcriptome of 3-week-old chicks of a heat-susceptible broiler line, a heat-resistant Fayoumi line, and their advanced intercross line (AIL).
  
  
  
  Transcriptome sequencing of 48 male chickens using Illumina HiSeq 2500 technology yielded an average of 33.9 million, 100 base-pair, single-end reads per sample. There were 8 times more differentially expressed genes (DEGs) (FDR < 0.05) in broilers (n = 627) than Fayoumis (n = 78) when comparing the acute-heat samples to the control (25 °C) samples. Contrasting genetic lines under similar heat treatments, the highest number of DEGs appeared between Fayoumi and broiler lines. Principal component analysis of gene expression and analysis of the number of DEGs suggested that the AIL had a transcriptomic response more similar to the Fayoumi than the broiler line during acute heat stress. The number of DEGs also suggested that acute heat stress had greater impact on the broiler liver transcriptome than chronic heat stress. The angiopoietin-like 4 (ANGPTL4) gene was identified as differentially expressed among all 6 contrasts. Ingenuity Pathway Analysis (IPA) created a novel network that combines the heat shock protein family with immune response genes.
  
  
  
  This study extends our understanding of the liver transcriptome response to different heat exposure treatments in distinct genetic chicken lines and provides information necessary for breeding birds to be more resilient to the negative impacts of heat. The data strongly suggest ANGPTL4 as a candidate gene for improvement of heat tolerance in chickens.
authors.affiliation: Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu Campus, Sichuan Province, China.|Department of Animal Science, Iowa State University, Ames, IA, USA.
authors.forename: Xi
authors.initials: X
authors.lastname: Lan
authors.affiliation: Department of Animal Science, Iowa State University, Ames, IA, USA.
authors.forename: John C F
authors.initials: JC
authors.lastname: Hsieh
authors.affiliation: Department of Animal and Food Sciences, University of Delaware, Newark, DE, USA.
authors.forename: Carl J
authors.initials: CJ
authors.lastname: Schmidt
authors.affiliation: Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu Campus, Sichuan Province, China.
authors.forename: Qing
authors.initials: Q
authors.lastname: Zhu
authors.affiliation: Department of Animal Science, Iowa State University, Ames, IA, USA. sjlamont@iastate.edu.
authors.forename: Susan J
authors.initials: SJ
authors.lastname: Lamont
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D002645:Chickens / Q000235:genetics*; D019295:Computational Biology / Q000379:methods; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D053263:Gene Regulatory Networks; D018869:Heat-Shock Response / Q000235:genetics; D006979:Hyperthermia, Induced; D008099:Liver / Q000378:metabolism*; D008297:Male; D015203:Reproducibility of Results; D013312:Stress, Physiological / Q000235:genetics*; D059467:Transcriptome
keywords: Chicken; Heat stress; Liver; Transcriptome