Peptide mapping of polymorphic myosin heavy chain isoforms in different muscle types of some freshwater teleosts

Characterization of myosin heavy chain (MYH) genes and their differential expression in white and red muscles of Chinese perch, Siniperca chuatsi

Fish skeletal muscle is composed of two anatomically and functionally different fiber layers, white or fast and red or slow muscles. Myosin, the major structural protein of fish skeletal muscle, contains multiple myosin heavy chain (MYH) isoforms involved in the high plasticity of muscle in response to varying functional demands and/or environmental changes. In this study, we comparatively assayed the cellular and ultrastructural feature of white and red skeletal muscles. Then, a total of 28 class II myosin heavy chain genes were identified in by searching the Chinese perch genome database. Among them, 14 genes code for the fast-muscle-type myosin heavy chain, and 7 genes code for the slow-muscle-type myosin heavy chain. Further, the different isoform gene structures, function domains, phylogenetic relations, and muscle-fiber type-specific expression were characterized. This is the first systematic work on the molecular characterization of class II myosin heavy chain isoforms and the differential analysis of their expression in red and white muscle tissues in Chinese perch Siniperca chuatsi. Our work provided valuable information for a better understanding of myh genes and their molecular characteristics, and the correlations of multiple myosin isoforms with potential functions in response to varying functional demands and/or environmental changes.

Effect of sodium bicarbonate and sodium chloride on aggregation and conformation of pork myofibrillar protein

To investigate the effect of sodium bicarbonate instead of sodium chloride, the changes in pH, turbidity, aggregation, and conformation of myofibrillar protein solution with various amounts of sodium chloride and sodium bicarbonate were studied. When the sodium bicarbonate was increased from 0% to 0.4%, accompanied by the sodium chloride being decreased from 2.0% to 0.8%, the pH increased about 1.20 unites; the absolute values of the Zeta potential, active sulfhydryl, and surface hydrophobicity increased significantly (p < 0.05); and the turbidity, particle size, and Ca²⁺-ATPase activity decreased significantly (p < 0.05). In addition, the Mg²⁺-ATPase activity was not significantly different (p > 0.05) when increasing sodium bicarbonate, implying that sodium bicarbonate did not affect the actin. Overall, the results indicated that an increase in sodium bicarbonate could improve solubility, expose more hydrophobic residues and sulfhydryl groups, and induce Ca²⁺-ATPase inactivation and protein unfolding, leading the myofibrillar protein to denaturation easily.

COX-2/iNOS regulation during experimental hepatic injury and its mitigation by cloudy apple juice

A number of enzymes and transcription factors have been correlated with disease etiology. In this study, involvement of cyclooxygenase-2 and inducible-nitric oxide synthase is examined during diethylnitrosamine (DEN)-induced hepatic injury and cloudy apple juice (CAJ) supplementation. Liver injury was administered in rats by single dose of DEN (10 ml/kg bwt of 1% DEN), while 10 ml/kg bwt CAJ daily was given after 2 h of latency in DEN-treated animals for two weeks. CAJ was characterized by HPLC and subsequently examined for antioxidant power. During the course of treatment liver function, collagen (hydroxyproline), malondialdehyde, protein oxidation, antioxidant enzymes, ATPases, nitrite levels were investigated along with liver histopathology and electron microscopy. COX-2 and iNOS proteins were also localized in liver specimens. The results demonstrated rich polyphenols and antioxidant activity in CAJ. CAJ supplementation significantly restored liver biochemistry and anatomy as revealed by the refurbished investigated parameters. CAJ treatment also declined COX-2 and iNOS activities in injured animals. Electron microscopy demonstrated rejuvenated hepatocytes, Kupffer cells, RER, mitochondria and nucleus in CAJ supplemented animals. The novel outcomes of this study suggest that CAJ potentiates hepatoprotection by stimulating antioxidant power and regulating the COX-2 and iNOS proteins in the liver during experimental liver injury.