Detection of differentially expressed genes in broiler pectoralis major muscle affected by White Striping – Wooden Breast myopathies

Abstract

White Striping and Wooden Breast (WS/WB) are abnormalities increasingly occurring in the fillets of high breast yield and growth rate chicken hybrids. These defects lead to consistent economic losses for poultry meat industry, as affected broiler fillets present an impaired visual appearance that negatively affects consumers' acceptability. Previous studies have highlighted in affected fillets a severely damaged muscle, showing profound inflammation, fibrosis, and lipidosis. The present study investigated the differentially expressed genes and pathways linked to the compositional changes observed in WS/WB breast muscles, in order to outline a more complete framework of the gene networks related to the occurrence of this complex pathological picture. The biochemical composition was performed on 20 pectoralis major samples obtained from high breast yield and growth rate broilers (10 affected vs. 10 normal) and 12 out of the 20 samples were used for the microarray gene expression profiling (6 affected vs. 6 normal). The obtained results indicate strong changes in muscle mineral composition, coupled to an increased deposition of fat. In addition, 204 differentially expressed genes (DEG) were found: 102 up-regulated and 102 down-regulated in affected breasts. The gene expression pathways found more altered in WS/WB muscles are those related to muscle development, polysaccharide metabolic processes, proteoglycans synthesis, inflammation, and calcium signaling pathway. On the whole, the findings suggest that a multifactorial and complex etiology is associated with the occurrence of WS/WB muscle abnormalities, contributing to further defining the transcription patterns associated with these myopathies.

Wooden‐Breast, White Striping, and Spaghetti Meat: Causes, Consequences and Consumer Perception of Emerging Broiler Meat Abnormalities

“…Chatterjee, Zhuang, Bowker, Rincon, and Sanchez‐Brambila (), Zambonelli et al. (), and Mudalal et al. () found similar results for breasts with combined WS and WB myopathies; while Baldi et al.…”

“…However, the studies carried out in order to quantify genes expression and identify putative causative genes leading to the development of WS (Pampouille et al., ) and/or WB (Abasht, Mutryn, Michalek, & Lee, ; Huber, Williams, & Athrey, ; Mutryn et al., ; Papah et al., ; Zambonelli et al., ) evidenced a complex etiology and a polygenic inheritance of the defect. Indeed, several genes and metabolites were differentially expressed between the pectoralis major affected by WS and/or WB and the unaffected (or only mildly affected) cases.…”

“…Moreover, dilation of the sarcoplasmic reticulum (increased diameter), mitochondrial swelling, vacuolation, cristae loss, and mitochondrial hyperplasia (identified as early ultrastructural changes associated with the occurrence of WB) are induced by the osmotic imbalances resulting from hypoxia and myodegeneration (Sihvo et al., ). In addition, impaired calcium homeostasis (Boerboom et al., ; Mutryn et al., ; Zambonelli et al., ) may lead to the activation of proteases and lipases (Zambonelli et al., ) thus contributing to myodegeneration and protein degradation (Petracci et al., ). Then, complex biological reactions and regenerative processes, aimed at alleviating inflammation and limiting cellular apoptosis and tissue necrosis, take place (Petracci et al., ).…”

“…Then, complex biological reactions and regenerative processes, aimed at alleviating inflammation and limiting cellular apoptosis and tissue necrosis, take place (Petracci et al., ). When myodegeneration overtake the regenerative capacity of the muscle, altered nucleotide (as evidence by an increased purine catabolism), and carbohydrate metabolisms are observed (Abasht et al., ; Papah et al., ; Zambonelli et al., ) and ultimately result in fibrosis and lipidosis, distinctive microscopic traits associated with the occurrence of these growth‐related abnormalities.…”

“…() reported a higher average weight of breast fillet with SM and simultaneous occurrence of WS/WB and WS/SM when compared to normal one. In relation to the height of the pectoralis major muscle, chicken breasts affected by WS, WB, SM, WS/WB, and WS/SM had higher height in both the cranial and medial regions of the breast compared to those in normal chicken breasts (Baldi et al., ; Kuttappan et al., ; Mudalal et al., , ; Zambonelli et al., ). However, in relation to the height in the caudal region, the WS and WS/SM presented a similar dimension to the normal group, while the SM, WB, and WS/WB breasts had a larger dimension (Baldi et al., ; Kuttappan et al., ; Mudalal et al., ; Mudalal et al., ; Zambonelli et al., ).…”