Coble Derrick J, Fleming Damarius, Persia Michael E, Ashwell Chris M, Rothschild Max F, Schmidt Carl J, Lamont Susan J
Department of Animal Science, Iowa State University, Ames, IA 50011, USA.
BMC Genomics. 2014 Dec 10;15(1):1084. doi: 10.1186/1471-2164-15-1084.
In broilers, high ambient temperature can result in reduced feed consumption, digestive inefficiency, impaired metabolism, and even death. The broiler sector of the U.S. poultry industry incurs approximately $52 million in heat-related losses annually. The objective of this study is to characterize the effects of cyclic high ambient temperature on the transcriptome of a metabolically active organ, the liver. This study provides novel insight into the effects of high ambient temperature on metabolism in broilers, because it is the first reported RNA-seq study to characterize the effect of heat on the transcriptome of a metabolic-related tissue. This information provides a platform for future investigations to further elucidate physiologic responses to high ambient temperature and seek methods to ameliorate the negative impacts of heat.
Transcriptome sequencing of the livers of 8 broiler males using Illumina HiSeq 2000 technology resulted in 138 million, 100-base pair single end reads, yielding a total of 13.8 gigabases of sequence. Forty genes were differentially expressed at a significance level of P-value < 0.05 and a fold-change ≥ 2 in response to a week of cyclic high ambient temperature with 27 down-regulated and 13 up-regulated genes. Two gene networks were created from the function-based Ingenuity Pathway Analysis (IPA) of the differentially expressed genes: "Cell Signaling" and "Endocrine System Development and Function". The gene expression differences in the liver transcriptome of the heat-exposed broilers reflected physiological responses to decrease internal temperature, reduce hyperthermia-induced apoptosis, and promote tissue repair. Additionally, the differential gene expression revealed a physiological response to regulate the perturbed cellular calcium levels that can result from high ambient temperature exposure.
Exposure to cyclic high ambient temperature results in changes at the metabolic, physiologic, and cellular level that can be characterized through RNA-seq analysis of the liver transcriptome of broilers. The findings highlight specific physiologic mechanisms by which broilers reduce the effects of exposure to high ambient temperature. This information provides a foundation for future investigations into the gene networks involved in the broiler stress response and for development of strategies to ameliorate the negative impacts of heat on animal production and welfare.
在肉鸡中，环境温度过高会导致采食量减少、消化效率低下、新陈代谢受损，甚至死亡。美国家禽业的肉鸡部门每年因高温造成的损失约为5200万美元。本研究的目的是描述周期性高环境温度对代谢活跃器官肝脏转录组的影响。本研究为高温对肉鸡新陈代谢的影响提供了新的见解，因为这是首次报道的通过RNA测序研究来描述高温对代谢相关组织转录组的影响。这些信息为未来的研究提供了一个平台，以进一步阐明对高环境温度的生理反应，并寻找减轻高温负面影响的方法。
使用Illumina HiSeq 2000技术对8只雄性肉鸡的肝脏进行转录组测序，产生了1.38亿条100碱基对的单端读数，总共获得了13.8千兆碱基的序列。在一周的周期性高环境温度处理后，有40个基因在P值<0.05且变化倍数≥2的显著水平上差异表达，其中27个基因下调，13个基因上调。通过对差异表达基因进行基于功能的 Ingenuity Pathway Analysis（IPA）构建了两个基因网络：“细胞信号传导”和“内分泌系统发育与功能”。热暴露肉鸡肝脏转录组中的基因表达差异反映了降低体内温度、减少高温诱导的细胞凋亡以及促进组织修复的生理反应。此外，差异基因表达揭示了一种生理反应，以调节因暴露于高环境温度而可能导致的细胞钙水平紊乱。
暴露于周期性高环境温度会导致代谢、生理和细胞水平的变化，这些变化可以通过对肉鸡肝脏转录组的RNA测序分析来表征。这些发现突出了肉鸡减轻暴露于高环境温度影响的特定生理机制。这些信息为未来研究参与肉鸡应激反应的基因网络以及制定减轻高温对动物生产和福利负面影响的策略奠定了基础。
