In two experiments, the effects of succinate and NADH (reduced nicotinamide adenine dinucleotide) on metmyoglobin reductase activity and electron transport chain-linked metmyoglobin reduction were investigated and compared. In experiment 1, metmyoglobin (MetMb), substrate and inhibitors were incubated with mitochondria. Comparsion of the effects of succinate and NADH on MetMb reduction was investigated. The MetMb percentage in sample treated with 8 mol L-1 succinate decreased by about 69% after 3 h incubation, and the effect was inhibited by the addition of 10 mol L-1 electron transfer chain complex II inhibitor malonic acid; the MetMb percentage in samples treated with 2 mol L-1 NADH decreased by 56% and the effect was inhibited by the addition of 0.02 mol L-1 electron transport chain complex I inhibitor rotenone. These results indicated that electron transport chain played an important role in MetMb reduction. Both complex II and complex I take part in the MetMb reduction in mitochondria through different pathways. NADH-MetMb reduction system was less stable than succinate- MetMb system. In experiment 2, the beef longissimus dorsi muscle was blended with different concentrations of succinate or NADH. Enhancing patties with higher concentration of succinate or NADH improved colour stability in vacuum packaged samples (P<0.05). These results verified that mitochondria electron transport chain is related to the MetMb reduction in meat system.

Wuschel-related homeobox (WOX) genes play essential, specific, and sometimes redundant roles in plant embryo development, shoot and root meristem maintenance, and plant development. Though much information was quickly gained with members of the WOX gene family of Arabidopsis, monocotyledonous crops, and gymnospermous conifers, little is known about perennial woody plants. In this study, we isolated the first WOX gene family member from grape (Vitis vinifera L. cv. Cabernet Sauvignon), and named it VvWOX4 based on its characteristic domains and phylogenetic analysis. The identity of VvWOX4 was validated by MALDI-TOF MS and Western blot with polyclonal antibody against Arabidopsis thaliana Wuschel. Functional analysis showed that VvWOX4 markedly increased shoot primordia structures when overexpressed under CaMV 35S promoter in tobacco. A different expression pattern was found for VvVOX4 compared with AtWUCHEL and its expression was detected in unique organs of grapevines. Besides the expression in the vegetative shoot apical meristem (SAM) of grape shoot tips, VvWOX4 is expressed in dormant winter buds, inflorescence, young leaves, and tendril tips, but not in root tips. In young leaves, the expression of VvWOX4 is strongly upregulated by wounding, and also by plant growth regulators such as 2 mg L-1 2,4-D, 1 mg L-1 NAA and 1 mg L-1 BAP treatments, while downregulation was monitored by 1 mg L-1 IBA treatment, and there was no response to 0.5 mg L-1 GA3 treatment. Together, our results revealed the first member of grape WOX gene family and indicated different roles and regulation of VvWOX4 in the perennial woody crop grapevine.