Molecular investigations of the effect of thermal manipulation during embryogenesis on muscle heat shock protein 70 and thermotolerance in broiler chickens

Abstract

Breeding and geneticsFull-length research article Molecular investigations of the effect of thermal manipulation during embryogenesis on muscle heat shock protein 70 and thermotolerance in broiler chickens ABSTRACT -The objective of this study was to elucidate the optimum protocol timing of thermal manipulation (TM) during embryogenesis, which underline genetic improvement of muscle thermotolerance acquisition. For the present study, 1,440 fertile eggs were divided randomly and equally into control (37.8 °C with 56% relative humidity) and four thermally manipulated groups (TM1, TM2, TM3, and T M4) subjected to 39 °C for 18 h with 65% relative humidity daily during different embryonic periods. Then, at day 35 post-hatch, all groups were subjected to thermal challenge at 43 °C for 6 h to identify the level of thermotolerance acquisition differences between them. Hsp70 mRNA expression was evaluated by using a relative quantitatively RT-qPCR. Single nucleotide polymorphisms sequence of the Hsp70 gene was evaluated by Sanger's sequencing method. Pectoral and thigh muscles samples were subjected to immunohistochemistry to detect Hsp70. Among TM conditions that were investigated, TM1 (39 °C for 18 h during embryonic days (ED) 7-11) induced a significant improvement in thermotolerance parameters (body temperature and T3 levels) during thermal challenge combined with an increase in the levels of Hsp70 mRNA and its protein with a high stability of nucleotide sequences in both pectoral and thigh muscles. The partial DNA sequence of Hsp70 gene in TM1 was reported, and nucleotide sequences were deposited in NCBI GenBank database with the accession numbers (MK852579) and (MK852580). Thigh muscle thermotolerance acquisition was higher than pectoral muscle during thermal challenge at 43 °C for 6 h. Thus, TM during ED7-11 may improve thermotolerance acquisition without adversely affecting performance.

Effects of Thermal Manipulation on mRNA Regulation of Response Genes Regarding Improvement of Thermotolerance Adaptation in Chickens during Embryogenesis

“…Notably, similar changes in the mRNA expression of Hsf1 and 2 were observed in the muscles of thermally manipulated chicks at ED 12 and 18 and on post-hatch days [ 48 ]. This suggests the spatial expression of Hsf genes between different tissues [ 49 ]. Notably, the activation of heat-inducible Hsf 1 and 3 has been demonstrated to require a specific temperature threshold [ 50 ].…”

“…Hsps are highly conserved proteins that are rapidly generated in organismal tissues in response to physical, chemical, or biological stimuli, such as heat exposure in chickens [ 7 , 51 ]. Hsps principally functions are facilitating protein structure and fold formation and promoting cell survival [ 49 , 52 ]. The classification of Hsps based on their high or low molecular weight varies by their ATP requirements for proper functionality.…”

“…Different TM protocols resulted in a significant increase in Hsp70 mRNA expression in the pectoral and thigh muscles [ 33 , 34 ], and the same was associated with enhanced thermotolerance, as previously reported by Al-Aqil and Zulkifli [ 9 , 54 ]. Ali et al [ 49 ] suggested that TM enhanced the expression of Hsp70 mRNA [ 33 , 47 , 48 , 55 , 56 ] in chickens. In addition, Hsp70 nucleotide and amino acid sequences are more constant in thermally manipulated chicks during their embryonic and post-hatch lives [ 49 ].…”

“…Ali et al [ 49 ] suggested that TM enhanced the expression of Hsp70 mRNA [ 33 , 47 , 48 , 55 , 56 ] in chickens. In addition, Hsp70 nucleotide and amino acid sequences are more constant in thermally manipulated chicks during their embryonic and post-hatch lives [ 49 ].…”

Embryonic thermal manipulation of poultry birds: Lucrative and deleterious effects

“…One of the most extensive benefits of TM is the capability to improve the thermotolerance in avian species by exposing eggs to high incubation temperatures (Ali et al, 2022; Alkan et al, 2013; Decuypere, 1984; Janke et al, 2002; Piestun et al, 2008a; Tzschentke & Basta, 2002). The ability to cope with severe heat or cold stress can last from few days to several weeks post hatch (Collin et al, 2007a; Piestun et al, 2008a; Saleh et al, 2020).…”