Tissue and allelic-specific expression of hsp70 gene in chickens: basal and heat-stress-induced mRNA level quantified with real-time reverse transcriptase polymerase chain reaction.

ABSTRACT

1. The 70 kDa heat shock proteins (hsp70) are a family of molecular chaperones, which promote protein folding and participate in many cellular functions. The objective of the current research was to investigate the relationship between tissue or allele and the expression of chicken hsp70 under normal growth conditions and during acute heat stress (44 degrees C for 4 h). 2. A total of 279 individuals were genotyped for two single nucleotide polymorphisms (A258G and C276G) in chicken hsp70 gene by single-strand conformation polymorphism (SSCP) analysis. 3. The mRNA abundance of chicken hsp70 genes was evaluated by real-time reverse transcriptase polymerase chain reaction (RT-PCR). The expression of hsp70 gene in the liver (9.83 +/- 0.84, 10(7)) was significantly higher than that in the muscle (4.42 +/- 0.36, 10(7)) under normal growth conditions. However, during acute heat stress, the expression of hsp70 gene in the brain (1.82 +/- 0.25, 10(9)) was the highest and was significantly different from those in the liver (1.08 +/- 0.16, 10(9)) and muscle (1.08 +/- 0.13, 10(9)). 4. The expression of hsp70 among different genotypes or haplotype combinations is quite different under normal and heat-stress conditions. The haplotype H3 (GC) is probably advantageous to improving heat resistance of chickens. 5. The results from the present study indicate that the expression of hsp70 in chickens is affected by heat stress, and is tissue- and allele-dependent.