Zahoor Imran, de Koning Dirk-Jan, Hocking Paul M
Division of Genetics and Genomics, Roslin Institute and R(D)SVS, University of Edinburgh, Easter Bush, Midlothian, EH25 9RG, UK.
Department of Animal Breeding and Genetics, University of Veterinary and Animal Sciences, Lahore, 54000, Pakistan.
Genet Sel Evol. 2017 Sep 20;49(1):69. doi: 10.1186/s12711-017-0346-x.
In recent years, the commercial importance of changes in muscle function of broiler chickens and of the corresponding effects on meat quality has increased. Furthermore, broilers are more sensitive to heat stress during transport and at high ambient temperatures than smaller egg-laying chickens. We hypothesised that heat stress would amplify muscle damage and expression of genes that are involved in such changes and, thus, lead to the identification of pathways and networks associated with broiler muscle and meat quality traits. Broiler and layer chickens were exposed to control or high ambient temperatures to characterise differences in gene expression between the two genotypes and the two environments.
Whole-genome expression studies in breast muscles of broiler and layer chickens were conducted before and after heat stress; 2213 differentially-expressed genes were detected based on a significant (P < 0.05) genotype × treatment interaction. This gene set was analysed with the BioLayout Express and Ingenuity Pathway Analysis software and relevant biological pathways and networks were identified. Genes involved in functions related to inflammatory reactions, cell death, oxidative stress and tissue damage were upregulated in control broilers compared with control and heat-stressed layers. Expression of these genes was further increased in heat-stressed broilers.
Differences in gene expression between broiler and layer chickens under control and heat stress conditions suggest that damage of breast muscles in broilers at normal ambient temperatures is similar to that in heat-stressed layers and is amplified when broilers are exposed to heat stress. The patterns of gene expression of the two genotypes under heat stress were almost the polar opposite of each other, which is consistent with the conclusion that broiler chickens were not able to cope with heat stress by dissipating their body heat. The differentially expressed gene networks and pathways were consistent with the pathological changes that are observed in the breast muscle of heat-stressed broilers.
近年来，肉鸡肌肉功能变化及其对肉质相应影响的商业重要性日益增加。此外，与体型较小的蛋鸡相比，肉鸡在运输过程中和高环境温度下对热应激更为敏感。我们推测热应激会加剧肌肉损伤以及参与此类变化的基因的表达，从而有助于识别与肉鸡肌肉和肉质性状相关的途径和网络。将肉鸡和蛋鸡暴露于对照或高环境温度下，以表征两种基因型和两种环境之间的基因表达差异。
在热应激前后对肉鸡和蛋鸡的胸肌进行了全基因组表达研究；基于显著的（P < 0.05）基因型×处理相互作用，检测到2213个差异表达基因。使用BioLayout Express和Ingenuity Pathway Analysis软件对该基因集进行分析，并确定了相关的生物学途径和网络。与对照和热应激蛋鸡相比，参与炎症反应、细胞死亡、氧化应激和组织损伤相关功能的基因在对照肉鸡中上调。这些基因的表达在热应激肉鸡中进一步增加。
对照和热应激条件下肉鸡和蛋鸡之间的基因表达差异表明，正常环境温度下肉鸡胸肌的损伤与热应激蛋鸡相似，并且在肉鸡暴露于热应激时会加剧。两种基因型在热应激下的基因表达模式几乎完全相反，这与肉鸡无法通过散热来应对热应激的结论一致。差异表达的基因网络和途径与热应激肉鸡胸肌中观察到的病理变化一致。
