Research Article

Effect of muscle-fiber type on glycogenin-1 gene expression and its relationship with the glycolytic potential and pH of pork

Published: September 04, 2013
Genet. Mol. Res. 12 (3) : 3383-3390 DOI: https://doi.org/10.4238/2013.September.4.4
Cite this Article:
(2013). Effect of muscle-fiber type on glycogenin-1 gene expression and its relationship with the glycolytic potential and pH of pork. Genet. Mol. Res. 12(3): gmr2500. https://doi.org/10.4238/2013.September.4.4
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Abstract

This study analyzed the effect of muscle-fiber type composition on glycogenin-1 (GYG) gene expression and its impact on pH. The longissimus dorsi (LD) muscle contains more type IIB fibers (75.10%) than does the psoas major (PM) muscle (41.58%), while the PM has more type I (3.65 vs 0.94%), type IIA (34.15 vs 10.63%), and type IIX (20.62 vs 13.33%) fibers. Compared with PM, glycolytic potential (GP), pH45 min, and DpH from 45 min to 24 h post-mortem were all relatively higher in LD. Glycogen metabolites (lactate and GP) were negatively correlated with pH24 h and positively correlated with DpH. Expression of GYG was generally higher in LD. GYG expression was positively correlated with glycogen metabolite (lactate and GP) content and DpH, and was negatively correlated with pH24 h. These data confirm that the muscle-fiber type and GP have significant effects on ultimate pH and pH decline, and suggest that expression of GYG in muscles is related to the metabolism of glycogen and may impact GP, ΔpH, and ultimate pH. High expression of GYG was associated with a high glycogen content, large pH decline, and low ultimate pH in muscles post-mortem.

This study analyzed the effect of muscle-fiber type composition on glycogenin-1 (GYG) gene expression and its impact on pH. The longissimus dorsi (LD) muscle contains more type IIB fibers (75.10%) than does the psoas major (PM) muscle (41.58%), while the PM has more type I (3.65 vs 0.94%), type IIA (34.15 vs 10.63%), and type IIX (20.62 vs 13.33%) fibers. Compared with PM, glycolytic potential (GP), pH45 min, and DpH from 45 min to 24 h post-mortem were all relatively higher in LD. Glycogen metabolites (lactate and GP) were negatively correlated with pH24 h and positively correlated with DpH. Expression of GYG was generally higher in LD. GYG expression was positively correlated with glycogen metabolite (lactate and GP) content and DpH, and was negatively correlated with pH24 h. These data confirm that the muscle-fiber type and GP have significant effects on ultimate pH and pH decline, and suggest that expression of GYG in muscles is related to the metabolism of glycogen and may impact GP, ΔpH, and ultimate pH. High expression of GYG was associated with a high glycogen content, large pH decline, and low ultimate pH in muscles post-mortem.