In the intracellular microenvironment of active muscle tissue, high rates of respiration are maintained at near-limiting oxygen concentrations. The respiration of isolated heart mitochondria is a hyperbolic function of oxygen concentration and half-maximal rates were obtained at 0.4 and 0.7 microM O(2) with substrates for the respiratory chain (succinate) and cytochrome c oxidase [N,N,N,N',N'-t...

We investigated the characteristics of ethylene biosynthesis associated with ripening in banana (Musa sp. [AAA group, Cavendish subgroup] cv Grand Nain) fruit. MA-ACS1 encoding 1-aminocyclopropane-1-carboxylic acid (ACC) synthase in banana fruit was the gene related to the ripening process and was inducible by exogenous ethylene. At the onset of the climacteric period in naturally ripened fruit...

A new glass capillary microelectrode for L-glutamate is described using pulled glass capillaries (tip size, approximately 12.5 microm) with a very small volume (approximately 2 microl) of inner solution containing glutamate oxidase (GluOx) and ascorbate oxidase. The operation of the electrode is based on capillary action that samples L-glutamate into the inner solution. The enzyme reaction by G...

To explore the role of plant mitochondria in the regulation of cellular redox homeostasis and stress resistance, we exploited a Nicotiana sylvestris mitochondrial mutant. The cytoplasmic male-sterile mutant (CMSII) is impaired in complex I function and displays enhanced nonphosphorylating rotenone-insensitive [NAD(P)H dehydrogenases] and cyanide-insensitive (alternative oxidase) respiration. Lo...

During senescence of broccoli (Brassica oleracea L. var. italica) florets (flower buds), the rate of ethylene production increased, almost paralleling the rapid increase in 1-aminocyclopropane-1-carboxylate (ACC) oxidase activity. The increase in ACC oxidase activity was strongly suppressed by the administration of cycloheximide, suggesting that it may have resulted from the de novo synthesis o...

We previously reported that hepatocytes exhibit a reversible suppression of respiration during prolonged hypoxia (PO2 = 20 torr for 3-5 h). Also, isolated bovine heart cytochrome c oxidase undergoes a reversible decrease in apparent Vmax when incubated under similar conditions. This study sought to link the hypoxia-induced changes in cytochrome oxidase to the inhibition of respiration seen in i...

BACKGROUND Red-skin root disease has seriously decreased the quality and production of Panax ginseng (ginseng). METHODS To explore the disease's origin, comparative analysis was performed in different parts of the plant, particularly the epidermis, cortex, and/or fibrous roots of 5-yr-old healthy and diseased red-skin ginseng. The inorganic element composition, phenolic compound concentration...