Embryo thermal manipulation: muscle transcriptional profile in chickens submitted or not to heat challenge 34d posthach

Meat type chickens have limited capacities to cope with high environmental temperatures, sometimes leading to important mortality in farms and subsequent economic loss. One of the strategies to increase the sustainability of broiler chicken production is to enhance their adaptive capacities to face heat exposure using heat conditioning (C) during embryogenesis. This strategy was shown to improve thermotolerance in later life. The aim of this study was to determine the effect of C (39.5°C, 12h/24 vs 37.8°C from d7 to d16 of embryogenesis) and of a subsequent heat challenge (32°C for 5h, CH) applied on d34, on global gene expression in the Pectoralis major muscle (PM). Chicken Genome Array (60 K) was used to compare muscle gene expression profiles of Control (T) and heat-conditioned C chickens (characterized by low body temperature) reared at 21°C, and reared at 32°C (TCH and CCH respectively) in a dye-swap design with four comparisons and 8 broilers per condition. Real-time RT-PCR was subsequently performed to validate differential expressions in each comparison. Gene ontology, clustering and network building strategies were used. This study was performed with the financial support of the French Agence Nationale de la Recherche, Project «Jeunes Chercheuses et Jeunes Chercheurs», ANR-09-JCJC-0015-01, THERMOCHICK. Four-condition experiment on chicken breast muscle samples, Controls at 32°C (TCH) vs. Controls at 21°C (T), heat-conditioned at 21°C (C) vs. Controls at 21°C (T), heat-conditioned at 32°C (CCH) vs. heat-conditioned at 21°C (C), heat-conditioned at 32°C (CCH) vs. Controls at 32°C (TCH). Biological replicates: 8 per treatment characterized by low body temperatures in C and CCH treatments and high body temperatures in T and TCH treatments.