Absolute expressions of hypoxia-inducible factor-1 alpha (HIF1A) transcript and the associated genes in chicken skeletal muscle with white striping and wooden breast myopathies

Abstract

Development of white striping (WS) and wooden breast (WB) in broiler breast meat have been linked to hypoxia, but their etiologies are not fully understood. This study aimed at investigating absolute expression of hypoxia-inducible factor-1 alpha subunit ( HIF1A ) and genes involved in stress responses and muscle repair using a droplet digital polymerase chain reaction. Total RNA was isolated from pectoralis major collected from male 6-week-old medium (carcass weight ≤ 2.5 kg) and heavy (carcass weight > 2.5 kg) broilers. Samples were classified as “non-defective” (n = 4), “medium-WS” (n = 6), “heavy-WS” (n = 7) and “heavy-WS+WB” (n = 3) based on abnormality scores. The HIF1A transcript was up-regulated in all of the abnormal groups. Transcript abundances of genes encoding 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 4 ( PFKFB4 ), lactate dehydrogenase-A ( LDHA ), and phosphorylase kinase beta subunit ( PHKB ) were increased in heavy-WS but decreased in heavy-WS+WB. Glyceraldehyde-3-phosphate dehydrogenase ( GAPDH ) was up-regulated in non-defective samples. The muscle-specific mu-2 isoform of glutathione S-transferases ( GSTM2 ) was up-regulated in the abnormal samples, particularly in the heavy groups. The genes encoding myogenic differentiation ( MYOD1 ) and myosin light chain kinase ( MYLK ) exhibited similar expression pattern, of which medium-WS and heavy-WS significantly increased compared to non-defective whereas expression in heavy-WS+WB was not different from either non-defective or WS-affected group. The greatest and the lowest levels of calpain-3 ( CAPN3 ) and delta-sarcoglycan ( SCGD ) were observed in heavy-WS and heavy-WS+WB, respectively. Based on micrographs, the abnormal muscles primarily comprised fibers with cross-sectional areas ranging from 2,000 to 3,000 μm 2 . Despite induced glycolysis at the transcriptional level, lower stored glycogen in the abnormal muscles corresponded with the reduced lactate and higher pH within their meats. The findings support hypoxia within the abnormal breasts, potentially associated with oversized muscle fibers. Between WS and WB, divergent glucose metabolism, cellular detoxification and myoregeneration at the transcriptional level could be anticipated.

Characterizing Woody Breast Myopathy in a Meat Broiler Line by Heat Production, Microbiota, and Plasma Metabolites

“…A recent study performed in broiler where they studied time series differential expression of genes in WB affected P. major using RNAseq showed molecular perturbations involving vasculature in early pathogenesis (32). Similarly, another study found the genes related to hypoxia were upregulated in WB affected muscle fibers (33), and microscopical morphometry of vessel density in muscle showed the compromised blood supply in affected tissue (34). Additionally, P. major histological or compositional analysis have exhibited increased lipid content in tissue as an important attribute of muscle myopathy (6,(35)(36)(37)(38).…”

Evaluation via Supervised Machine Learning of the Broiler Pectoralis Major and Liver Transcriptome in Association With the Muscle Myopathy Wooden Breast

“…Prior systematic studies of the abnormal muscle phenotype referred to as wooden breast using gene expression measurements has identified multiple processes that may contribute to the development of the myopathy. Processes including muscle fiber regeneration, inflammatory response, myodegeneration, hypoxia, fibrosis, lipidosis, and altered energy metabolism are likely involved in the manifestation of wooden breast (Mutryn et al, 2015;Zambonelli et al, 2016;Papah et al, 2018;Malila et al, 2019;Petracci et al, 2019). This study attempts to connect organismal level physiology and metabolism with the activity in the breast muscle by including the evaluation of liver gene expression by a novel analysis method.…”

“…The cause of WB is currently unknown, but it is more prevalent in older, heavier male broilers than young birds (Kuttappan et al, 2017;Brothers et al, 2019). Larger breast muscle has been associated with hypertrophied muscle fibers which is thought to impact blood supply and number of satellite cells that are needed in muscle regeneration (Daughtry et al, 2017;Malila et al, 2019).…”

The Potential of Guanidino Acetic Acid to Reduce the Occurrence and Severity of Broiler Muscle Myopathies

“…The specific origin of these myopathies has not been well elucidated. Recent findings have linked their onset with hypoxia (Malila et al, 2019) due to reduced vascularization (Sihvo et al, 2018), phlebitis (Papah et al, 2017;Chen et al, 2019), and glucolipotoxicity (Mutryn et al, 2015;Abasht et al, 2016;Lake and Abasht, 2020). The final result is a muscle with defective energy-generating pathways combined with a deficiency and/or dysfunction of tissue ATPases, having consequences in myodegeneration and on muscle fiber contraction degree (Baldi et al, 2020).…”