Effect Of Endoplasmic Reticulum Stress On Tenderness During Chicken Post-Mortem Ageing

Tenderness,as a key indicator of meat quality,has become a key factor in consumer purchase and business value realization.At present,in addition to“maturation process”,which is generally followed by the method of refrigerating the carcass at 4°C after slaughtered in order to achieve the process of meat ripening.Some enterprises accelerate the tenderization of meat through electrical stimulation,ultrasonic stimulation,carcass suspension,and exogenous proteases.After slaughter,the meat will immediately enter a rigid period,then slowly mature and eventually turn into meat products,and the maturity is the most important stage in improving meat tenderness.After slaughter,the muscles of animal would be in the state of hypoxia ischemia.In addition to apoptosis,it also lead to the phenomenon of endoplasmic reticulum stress in animal cells.The effect of mitochondria-mediated apoptosis on meat quality has been confirmed.However,the relationship between endoplasmic reticulum stress and the tenderization of meat has not been studied.To solve this issue,this study used chicken as a research object to study the IRE1and Caspase12 signals of endoplasmic reticulum stress during chicken maturation,and skeletal muscle cells of mice are cultured and hypoxia ischemia cell model is made.Pathway,the regulatory effects of related regulatory factors GRP78,Caspase-12,Caspase-9,Caspase-3 etc.To explore the key signaling factors that promote endogenous chicken maturation during endoplasmic reticulum stress-mediated apoptosis.Furthermore,the apoptosis inducer was used to analyze the effect of signal factors on the degradation of chicken myofibrils.The research results will improve the existing theory of mature meat tenderization and provide new ideas and theoretical guidance for improving the tenderness of meat.The specific research contents and results are as follows:1.The primary skeletal muscle cell culture system was established and the Hypoxia-ischemia model after slaughter has been built.Primary skeletal muscle cells were isolated from the hind leg muscles of mice by two-step digestion,the cells were differentially attached and purified.The normal cultured primary cells were transferred to a hypoxic ischemic chamber,and the cells were cultured in a serum-free medium.The results showed that the cell morphology was shrunken and apoptotic bodies appeared.The model of hypoxia-ischemia was simulated.The results of Western blot showed that the expression of BIP and Caspase12 increased by 57.29%and37.72%respectively,demonstrating the occurrence of endoplasmic reticulum stress under post-mortem hypoxic-ischemic conditions.2.The apoptosis of skeletal muscle cell is aggravated by treatment with Cacl₂ and tea polyphenols.MTT was used to test the influence of Cacl₂ and Tea polyphenols on skeletal muscle cell apoptosis and its optimal concentration.Apoptosis was determined by AO/EB staining at different concentrations.The results showed that after treated with 10 m M Cacl₂ and 5mg/ml tea polyphenol,the apoptosis of skeletal muscle cells was aggravated.3.Treatment of Cacl₂ and tea polyphenols exacerbates the activation of the Caspase12pathway during chicken maturation.In this study,chicken breast was used as the research object.After slaughtering,it was rapidly cooled and treated with Cacl₂ and Tea polyphenol.Naturally matured at 4°C for 0 d,1 d,3 d,5 d.Caspase12 pathway downstream target Caspase9,Caspase3 expression were detected.The results showed that Caspase12 pathway was activated,cascade-related protein expression factor increased,cleaved-Caspase12 peak was 1.47,1.24 times of 0 days;the peak of cleavage Caspase9 was 1.78 and 1.51 times of 0 days respectively;And finally,it was applied to Caspase3,and the expression of Pro-caspase3 was decreased by 23.12%and16.59%,respectively.It is indicated that the apoptosis-inducing agent can activate Caspase12,cleave Caspase9,and then activate Caspase3.The cascade reaction was initiated and apoptosis was aggravated.4.Effect of Cacl₂ and Tea Polyphenols Treatment on Meat Tenderness.HE-slice staining was used to observe the changes of tissue structure treated by apoptosis inducer.The shear stress of different treatments was determined.The changes of Desmin was detected by extracting myofibrillar protein.Meanwhile the degradation of troponin-T was detected by SDS-PAGE.It was confirmed that treatment with these two apoptosis inducing agents can activate endoplasmic reticulum stress and enhance the degradation of myofibrils to promote meat maturation.