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In order to investigate the regulatory effect of B-cell lymphoma-2 (Bcl-2) on cell apoptosis and water retention in postmortem Qinchuan beef, the longissimus dorsi muscle of Qinchuan cattle was injected with either 200 μmol/L glycochenodeoxycholic acid (GCDA) or 10 μmol/L 2-ethyl-3-methylpentanamide (ABT-737) solution and aged at 4 ℃ postmortem. After 0, 6, 12, 24, 48, 72 and 120 h, the changes in Bcl-2 and Bcl-2-associated X protein (Bax) contents, the concentrations of endoplasmic reticulum and mitochondrial calcium ion, voltage-dependent anion channel protein 1 (VDAC1) expression, calpain content, the mitochondrial apoptosis pathway and water retention were determined. The results showed that at 6 h after slaughter, the Bcl-2 content of the GCDA-treated group was significantly higher than that of the control group (P < 0.01), the calcium ion concentration in the endoplasmic reticulum was significantly lower than that of the control group (P < 0.01), and cooking loss was significantly lower in both treatment groups than the control group (P < 0.05). At 12 and 24 h post-slaughter, the Bcl-2 content of the ABT-737-treated group was significantly lower than that of the control group (P < 0.01). At 12 and 120 h post-slaughter, the endoplasmic reticulum calcium ion, mitochondrial calcium ion and calpain levels in the ABT-737-treated group were significantly greater than those in the control group (P < 0.01). During 0–120 h post-slaughter, the total expression of VDAC1 in both treatment groups was lower than that in the control group. In summary, during the postmortem aging of Qinchuan beef, under the regulation of Bcl-2, calcium overload occurs through VDAC1-facilitated calcium transport, resulting in the activation of calpain, and the overloading of Ca2+ in mitochondria promotes the activation of caspase-9 and caspase-3, thus inducing cell apoptosis. The higher the degrees of cell apoptosis and caspase activation, the higher the degree of degradation of myofibrillar proteins, and the poorer the water-holding capacity of the meat.

In order to explore the effects of basigin (BSG) on the mitogen activated protein kinase (MAPK) signaling pathway and apoptosis in Qinchuan cattle muscle during postmortem maturation, the changes in BSG and related differentially expressed proteins were analyzed by 4D-label free quantification (4D-LFQ). The BSG inhibitor tunicamycin was injected into the longissimus dorsi of Qinchuan cattle after slaughter, and the expression levels of key proteins in the MAPK signaling pathway during storage at 4 ℃ were determined by Western blotting. An apoptosis detection kit was used to determine the change in the activity of caspase-3. The results showed that the expression of BSG increased first and then decreased during the postmortem storage period of Qinchuan cattle muscle. Through Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis, it was found that BSG and related differentially expressed proteins were significantly annotated to the oxidative phosphorylation pathway, calcium signal pathway and MAPK signaling pathway, indicating that BSG played an important role through the MAPK signaling pathway. In addition, for the tunicamycin group, the relative expression of the key proteins in the MAPK signaling pathway was significantly down-regulated, indicating that BSG inactivated the MAPK signaling pathway. This finding lays a good foundation for exploring the effect of BSG on the MAPK signaling pathway. After inhibiting BSG expression, caspase-3 activity in the tunicamycin group increased significantly, indicating that apoptosis was an important link in cell injury mechanism, and tunicamycin acted on the N-terminal structure of BSG to deglycosylate the protein and inhibited the folding of intracellular proteins and consequently their biological activity, thereby inducing cell apoptosis.

This study addressed the effect of adenosine 5’-diphosphate (ADP) ribosylation on the mitochondrial function and quality of Qinchuan cattle meat during early postmortem aging. The Longissimus dorsi muscle of Qinchuan cattle treated with 20 µmol/L rucaparib, a poly(ADP-ribose) polymerase 1 (PARP1) inhibitor, were evaluated for mitochondrial indices, myofibrillar fragmentation index (MFI), shear force, pH, and other quality indices after being stored for 0 h, 6 h, 12 h, 2 d, 4 d, and 8 d and the expression levels of PARP1 and desmin were detected using Western blot. The results showed that the content of reactive oxygen species (ROS) in the treated group was significantly lower than that in the control group (P < 0.05) during 0 h–8 d (except 12 h) after slaughter. The caspase-3 activity and MFI in the treated group were significantly lower than those in the control group (P < 0.05) during 0–12 h. Mitochondrial membrane potential during 2–4 d as well as succinate dehydrogenase (SDH) activity during 4–8 d were significantly higher in the treated group than in the control group (P < 0.05). These findings indicate that PARP1 inhibition, which characterizes ADP ribosylation, can slow down the decrease in mitochondrial membrane potential and increase SDH activity, preserving mitochondrial function to some extents and delaying the decrease in MFI and the degradation of desmin and thereby meat tenderization.

The tenderness of mutton is one of the qualities of prime lamb meat. This study investigated the effects of postmortem time on different meat quality parameters and examined the transcriptome involved in the tenderisation of lamb meat during postmortem ageing. Results showed that the pH value and adenosine triphosphate (ATP) levels considerably decreased in the early stage (0–4 days) of postmortem ageing, whereas caspases‐3 activities increased (0–4 days). The pH value notably increased in the later stage (4–8 days), while ATP levels and caspases‐3 activities decreased (4–8 days). The transcriptional changes at the early stage of ageing (0–4 days) play important regulatory roles in translation and hydrogen transmembrane transport. Mitochondrial genes, ATP synthase F0 subunit 6, cytochrome c oxidase subunit I, cytochrome c oxidase subunit II, and cytochrome b were identified as the core genes associated with Tan lamb tenderness. In conclusion, mitochondrial genes most likely contribute to lamb meat tenderness as they affect the activation of caspase‐3. [ABSTRACT FROM AUTHOR]