Differential expression of calcium-regulating genes in heat-stressed turkey breast muscle is associated with meat quality

Abstract

Aberrant postmortem Ca(2+)-regulation in the early postmortem period is associated with the occurrence of inferior meat quality in turkeys, described as pale, soft, and exudative (PSE). The objective of the current study was to quantify expression of 4 candidate genes responsible for maintaining Ca(2+) homeostasis in turkey skeletal muscle as a function of heat stress: α and β ryanodine receptors (RYR; Ca(2+)-release channels), the sarco/endoplasmic reticulum Ca(2+)-ATPase 1 (SERCA1), and the sarcoplasmic reticulum, Ca(2+)-storage protein calsequestrin (CASQ1). Two genetic lines of turkeys were used: a growth-selected commercial line and a randombred control line. Market-age birds were subjected to one of 5 heat stress treatments: no heat, 1 d, 3 d, 5 d, or 7 d of heat followed by 7 d of ambient temperature. Breast muscle samples were harvested and classified as normal or PSE using the meat quality parameters percentage of marinade uptake and percentage of cook loss. These parameters differed significantly by line, heat stress treatment, and meat quality status. Expression of candidate genes was measured using TaqMan quantitative PCR. Heat treatment was associated with significantly enhanced expression of αRYR, βRYR, and CASQ1 in normal muscle from both lines. Conversely, mRNA abundance of these genes was reduced in PSE muscle from both lines and recovered or increased by 7 d + 7 d of rest. Genetic line differences were observed at several time points. Expression of SERCA1 in both normal and PSE samples from both lines was unchanged or trended downward with heat stress. Taken together, genetic line and heat-stress treatment affected the expression of important Ca(2+)-regulating genes in association with meat quality status. The data suggest that birds whose meat leads to PSE may fail to respond to heat stress appropriately due to a delay in the upregulation of the important calcium-regulating genes: αRYR, βRYR, and CASQ1.

Disorder of endoplasmic reticulum calcium channel components is associated with the increased apoptotic potential in pale, soft, exudative pork

“…Therefore, the SR in PSE meat would consist of higher numbers of calcium releasing channels and lower numbers of calcium uptake channels, suggesting a high sarcoplasmic calcium concentrations which was most likely to occur given the current consensus Sporer, et al, 2012). The process generating a mature protein molecule starting from the extracellular stimuli always takes almost 1 hour on average under normal physiological conditions, which involves in mRNA transcription,…”

“…In previous research, high sarcoplasmic calcium concentrations shortly after slaughter (< 1 h) have been considered to be a common feature of PSE meat in both pig and chicken (Cheah, Cheah, Crosland, Casey, & Webb, 1984;Greaser, et al, 1969;Sporer, et al, 2012). However, it is difficult to directly measure the calcium concentration and…”

“…Therefore, important functional components of the calcium channels, such as RyR (Weaver, et al, 2000) located on the sarcoplasmic reticulum (SR) membrane, have been used to estimate the calcium status in many tissues such as cardiac and skeletal muscles (Sporer, et al, 2012). Also RyR, IP3R and SERCA family have been investigated for their role in transporting calcium to, and from, the sarcoplasm Lencesova, et al, 2002;Periasamy, Bhupathy, & Babu, 2008;Streb, Irvine, Berridge, & Schulz, 1983).…”

“…For instance, genetic mutation of RyR and SERCAs is highly correlated with the appearance of PSE meat in both pig and chicken Sporer, Zhou, Linz, Booren, & Strasburg, 2012;Toyoshima, Nakasako, Nomura, & Ogawa, 2000;Weaver, Dixon, & Schaefer, 2000). Also, the expression variance of both SERCA and IP3R can induce the skeletal muscle calcium disorders and PSE meat appearance (J.…”

Differential gene expression between normal and pale, soft, and exudative turkey meat

“…With the onset of heat stress, the PSE meat showed a significant delay in the upregulation of RYR isoforms αRYR and βRYR, and of calsequestrin, the high-capacity, low-affinity Ca 2+ binding protein located in the lumen of the SR. Transcript abundance of the sarco/endoplasmic reticulum Ca 2+ -ATPase 1 (SERCA1) remained unchanged. This previous study of Sporer et al (2012) suggests a complex manifestation of changes in gene expression associated with development of PSE in turkey. It is possible that differential expression of unidentified genes other than SR Ca 2+ regulators may be revealed in PSE turkey.…”