7th European Symposium on Poultry Genetics 5th‐7th October 2011 (Peebles Hydro)

Identification of novel pathways/ for muscle damage in broilers

I. Zahoor1, D. J. deKoning1,2 and P. M. Hocking1 1The Roslin Institute and R(D)SVS, University of Edinburgh, Easter Bush, Midlothian, EH25 9RG, Scotland, UK; Swedish University of Agricultural Sciences, Uppsala, Sweden. [email protected]

Broilers are considered susceptible to ante-mortem stressors and their muscles are characterised by pathological damage and heat-stress is known to have its role in further exacerbation of this condition. Present study was designed to find out the role of heat-stress in muscle damage and genes involved in muscle damage. 32 microarray slides (8 broiler heat stressed, 8 broiler controls, 8 layer heat stressed, 8 layer control) were analysed in GenStat, 2214 no. of probes were found significant for Breed × Treatment interaction. These Significant probes were further analysed in BioLayout Express. Some interested clusters were selected on the basis of their respective graphs, based on expression data and their probes were analysed in Ingenuity Pathway Analysis (IPA) to get the respective canonical pathways. In these clusters, 287 genes were present which are involved in stress response, inflammation and tissue damage, on the basis of their GO terms and published literature. In all these clusters the expression levels of control broilers were higher than layers (although the layers had 0.960C higher body temperature than broilers in control condition which suggest that BC were more stressed than layers) and heat-stress resulted in further exacerbation of these differences. From the pathway analysis of these probes, some significant pathways were selected on the basis of their relevance to inflammation, stress, and tissue damage e.g. fMLP Signaling in Neutrophils, CCR3 Signaling in Eosinophils and Chemokine Signalling are involved in inflammation, increase intracellular calcium (Garcia-Rodriguez and Rao, 2000; Renieri et al., 2008) production of reactive oxygen species (ROS) (Kim et al., 2008), degranulation and tissue damage. In all of these 3 pathways, G [G alpha, G beta and G gamma (GNAI1, GNB5, GNG2)] (Lehmann et al., 2008) and HRAS (Woulfe et al., 2002) are the main genes which were upregulated and involved in initiating the series of cascades which up-regulate the downstream molecules involved in inflammation and tissue damage. Moreover, in addition to these, CCR3 Signaling in Eosinophils (Sabroe et al., 2005) is involved in connective tissue disorders that would be expected to increase if connective tissues cannot keep pace with muscle fibre radial growth.

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7th European Symposium on Poultry Genetics 5th‐7th October 2011 (Peebles Hydro)

SABROE I., JORRITSMA A., STUBBS V.E., XANTHOU G., JOPLING L.A., PONATH P.D., WILLIAMS T.J., MURPHY P.M. and PEASE J.E. (2005) The carboxyl terminus of the chemokine receptor CCR3 contains distinct domains which regulate chemotactic signaling and receptor down-regulation in a ligand-dependent manner. Eur J Immunol 35, 1301-1310.

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