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Calpain System (calpain + system)
Selected AbstractsPostmortem Calcium Chloride Injection Alters Ultrastructure and Improves Tenderness of Mature Chinese Yellow Cattle Longissimus MuscleJOURNAL OF FOOD SCIENCE, Issue 3 2006Baohua Kong ABSTRACT: This study was conducted to test the hypothesis that postmortem calcium injection could activate the calpain system in mature Chinese Yellow Cattle muscle, thereby promoting meat tenderization through disruption of the myofibril structure during aging. A 10% (w/w) injection of CaCl2 (300 mM) solution lowered the Warner-Bratzler shear values of longissimus muscle by more than 30% (P < 0.05), even with only 24 h postmortem storage when compared with noninjected or water-injected controls. The accelerated meat tenderization by the Ca2+ treatment paralleled the changes in myofibril fragmentation index and fracture of the myofibril ultrastructure throughout the sarcomere but most notably around the I-bands and the Z-disks. Injection of ZnCl2 (50 mM) largely inhibited these proteolytic changes. The colorimetric L* and a* values were not affected by CaCl2 nor by ZnCl2 injection. The results suggest that postmortem CaCl2 injection can be used to help resolve the toughness problem of mature Chinese Yellow Cattle meat and shorten the aging time required to achieve adequate tenderness. [source] Calpain-dependent proteolysis of NF2 protein: Involvement in schwannomas and meningiomasNEUROPATHOLOGY, Issue 3 2000Yoriyoshi Kimura The neurofibromatosis type 2 (NF2) protein, known as merlin or schwannomin, is a tumor suppressor, and the NF2 gene has been found to be mutated in the majority of schwannomas and meningiomas, including both sporadically occurring and familial NF2 cases. Although the development of these tumors depends on the loss of merlin, the presence of tumors lacking detectable NF2 mutations suggests different mechanisms for inactivating merlin. Recent studies have demonstrated cleavage of merlin by calpain, a calcium-dependent neutral cysteine protease, and marked activation of the calpain system resulting in the degradation of merlin in these tumors. Increased turnover of merlin by calpain in some schwannomas and meningiomas exemplifies tumorigenesis linked to the calpain-mediated proteolytic pathway. [source] Relationships among calpastatin single nucleotide polymorphisms, calpastatin expression and tenderness in pork longissimus,ANIMAL GENETICS, Issue 5 2009A. K. Lindholm-Perry Summary Genome scans in the pig have identified a region on chromosome 2 (SSC2) associated with tenderness. Calpastatin is a likely positional candidate gene in this region because of its inhibitory role in the calpain system that is involved in postmortem tenderization. Novel single nucleotide polymorphisms (SNP) in calpastatin were identified and used to genotype a population (n = 1042) of Duroc,Landrace,Yorkshire swine for association with longissimus lumborum slice shear force (SSF) measured at days 7 and 14 postmortem. Three genetic markers residing in the calpastatin gene were significantly associated with SSF (P < 0.0005). Haplotypes constructed from markers in the calpastatin gene were significantly associated with SSF (F -ratio = 3.93; P -value = 0.002). The levels of normalized mRNA expression of calpastatin in the longissimus lumborum of 162 animals also were evaluated by real-time RT-PCR and were associated with the genotype of the most significant marker for SSF (P < 0.02). This evidence suggests that the causative variation alters expression of calpastatin, thus affecting tenderness. In summary, these data provide evidence of several significant, publicly available SNP markers associated with SSF that may be useful to the swine industry for marker assisted selection of animals that have more tender meat. [source] Cell death in lens epithelial cells after stimulation of the sigma-2 receptorACTA OPHTHALMOLOGICA, Issue 2009JO KARLSSON Purpose The aim was to investigate the mechanisms of cell death in lens epithelial cells after administration of siramesine, a sigma-2 receptor agonist. Methods Human lens epithelial cells in culture were exposed to siramesine and examined for morphological changes using DIC or calcein as a cytoplasmic marker. Lysosomes were studied using acridine orange and MagicRed. Proteolytic activity of the proteasome, calpain, caspases and cathepsins in living cells or cell extracts were studied using different fluorogenic substrates. Results Siramesine at low concentrations increased the cytoplasmic proteolytic activity of the proteasome and the calpain system. Early effects was also observed with respect to lysosomal morphology, acidity and function. Activation of caspase-3 and the appearance of nuclei with an apoptotic morphology were also found. Conclusion Siramesine at very low concentrations affects lens epithelial cells with perturbation of the major proteolytic systems, lysosomal morphology and results in caspase activation and cell death. Siramesine may be a promising substance for clinical studies concerning the treatment of PCO. [source] | ||||||||||