Oxygen Consumption and Antioxidant Status of Plant Cells Cultured with Oxygenated Perfluorocarbon
Inert, respiratory gas-dissolving perfluorochemical (PFC) liquids can be used to regulate the supply of oxygen and carbon dioxide in both prokaryotic and eukaryotic (including human) cells in culture. However, the underlying biochemical changes in such cells, especially in relation to oxygen-sensitive pathways, are poorly understood. PFCs have been exploited as oxygen carriers to enhance mitosis during the culture of isolated protoplasts (naked cells from which the cell walls have been removed) of several plant species (Lowe et al., 1998), with subsequent increases in biomass from protoplast-derived cells. Whilst oxygen is vital in aerobic systems, its reduction may generate highly reactive oxygen species, such as superoxide (O2 -), which can have deleterious effects on cellular metabolism. Interestingly, there have been few studies on changes in cellular metabolism or on the activities of enzymes responsible for removal of reactive oxygen species in cells during culture with PFCs. Aerobic organisms have evolved enzyme systems for scavenging oxygen radicals, thus protecting against oxidative damage. One such group of enzymes, the superoxide dismutases (SOD), react with superoxide anions to produce hydrogen peroxide. The latter, in turn, is converted by catalases (CAT) to H2O and oxygen. This study has evaluated the beneficial effects of PFC-facilitated oxygen enhancement on changes in (1) cellular SOD (EC 220.127.116.11) and CAT (EC 18.104.22.168) activities, (2) the rate of oxygen consumption, as assessed by a Clark-type oxygen microelectrode, and (3) mitochondrial membrane potential (MMP) assessed using Rhodamine 123 fluorescence.
KeywordsMitochondrial Membrane Potential Oxygen Carrier Mitotic Division Scavenge Oxygen Radical Cellular Oxygen Consumption
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