Dynamic expression of HSP90B1 mRNA in the hypothalamus of two Chinese chicken breeds under heat stress and association analysis with a SNP in Huainan chickens

The effects of heat stress on HSP90B1 messenger RNA (mRNA) expression in the hypothalamus of chicken were investigated and HSP90B1 variations were detected. Females of two Chinese chicken breeds (Huainan and Wenchang) were used for the experiments. At 64 days of age, the ambient temperature (24 ± 1°C) was increased to 35 ± 1°C for 24 h (heat stress), then decreased to 24 ± 1°C for 24 h (recovery). Hypothalamus samples were collected at 0, 12, and 24 h during heat stress, as well as 12 and 24 h during recovery. The HSP90B1 mRNA expression increased significantly during heat stress and significantly decreased during recovery being higher in Huainan chickens. Fifteen primer pairs were designed to amplify the exons of HSP90B1 by a polymerase chain reaction, and single nucleotide polymorphisms (SNPs) were detected by Sanger sequencing. In Huainan chickens, we identified a SNP (NC_006088.3:g.6798G>A) in exon 14 of HSP90B1 which did not cause amino acid variation but caused a codon for glutamic acid change from GAG to GAA. The frequencies for genotypes AA, GA, and GG were 0.49, 0.27, and 0.24, respectively. Individuals with the GG genotype survived heat stress at 42°C for a longer time (248.2 ± 39.3 min) than individuals with GA and AA genotypes, which survived for 227.2 ± 44.5 min and 179.3 ± 36.5 min, respectively. The results suggested that the increased heat tolerance was associated with the higher expression of HSP90B1, and genotype GG could be used as a potential marker for heat resistance in chickens.