Quantification of viable biomass in biofilm reactors by extractable lipid phosphate

 Lipid phosphate, which is a measure of viable biomass, was determined using biofilm samples from three different laboratory-scale reactors. The analysis procedure proposed in the literature was modified and tested for suitability in experiments with biofilm reactors. The microbial contents of the biofilms studied are compared in three types of reactor. Received: 2 November 1994/Accepted: 23 January 1995     

Energy contents and organic constituents in Antarctic and south Chilean marine brown algae

The content of proteins, lipids and carbohydrates and the calorific contents in six Antarctic and three south Chilean brown algae were determined. These constitute the first reports of chemical composition in the endemic Antarctic species Cystosphaera jacquinotii, Phaeurus antarcticus and Desmarestia antarctica. There were no marked differences in total energy levels between Antarctic and cold-temperate species (values between 10.6 and 13 kJ g^–1 dry weight). However, species such as Adenocystis utricularis showed significantly higher ash-free energy (26.3 kJ), which is explained in terms of morpho-functional differentiation. Ascoseira mirabilis and Phaeurus antarcticus showed high total lipids (2.1–2.2% dry weight) and soluble carbohydrates (5.9 and 3.4% dry weight). In general, algae from Chile had similar energy levels and no obvious differences in organic content could be found.     

The effect of the olive phenolic compound, oleuropein, on growth and enterotoxin B production by Staphylococcus aureus

The presence of low concentrations (0.1% w/v) of oleuropein, a phenolic compound extracted from olives, delayed the growth of Staphylococcus aureus in NZ amine A and brain heart infusion media modified by the addition of growth factors and glucose (NZA + and BHI +), as indicated by changes in conductance, whilst higher concentrations (0.4–0.6% w/v) inhibited growth completely. Intermediate concentrations of oleuropein (0.2%) prevented growth in BHI + but allowed growth to occur in NZA + despite an extended lag phase (30 h). Concentrations of oleuropein > 0.2% inhibited growth and production of enterotoxin B in both types of media. Lower levels (0.1%) did not affect the final viable count and production of toxin in BHI + but decreased the number of viable organisms and reduced the toxin production in NZA + by eightfold. An increase in the concentration of oleuropein resulted in a decrease in the amount of glucose assimilated and consequently the amount of lactate produced. In addition, oleuropein prevented the secretion of a number of exoproteins. Addition of oleuropein during the exponential phase appeared to have no effect on the growth of Staph. aureus in NZA +.     

Dynamics of calmodulin in cerebral structures under the action of modulated UHF electromagnetic fields]

The influence of modulated UHF-electromagnetic fields (low intensity) on calmodulin levels in several brain structures was studied. It was shown that UHF-electromagnetic fields influence calmodulin levels in the hypothalamus and sensorimotor cortex. Its effect depends on modulation regimes.     

Hydrogen peroxide production by monoamine oxidase in isolated rat-brain mitochondria: its effect on glutathione levels and Ca2+ efflux

H2O2 production and accumulation during incubation of isolated rat-brain mitochondria with substrates of monoamine oxidase A and B were investigated. All substrates gave rise to an accumulation of H2O2 which was inhibited by malate + pyruvate or isocitrate, consistent with a need for mitochondrial NADPH to maintain glutathione in the reduced state. However, in the absence of these additions the level of reduced glutathione decreased only by about 30%, indicating that only a fraction of the mitochondrial glutathione pool was accessible to the glutathione peroxidase and glutathione reductase activities responsible for the continuous removal of H2O2 generated by monoamine oxidase. The H2O2 accumulation was also inhibited by externally added reduced glutathione or NADPH but not NADH. External NADPH was oxidized by added oxidized glutathione but not alpha-ketoglutarate + NH4+. These results suggest that the removal of H2O2 generated by monoamine oxidase proceeds by way of special fractions of glutathione peroxidase and glutathione reductase that are located in the intermembrane space of mitochondria in such a way that they can react with both intra- and extra-mitochondrial glutathione and NADPH, possibly at the contact sites between the inner and outer mitochondrial membranes. Evidence is also presented that H2O2 generated by monoamine oxidase enhances Ca2+ release from mitochondria and may thus function as a regulator of mitochondrial Ca2+ efflux.     

Perfluorooctane sulfonamide: a structurally novel uncoupler of oxidative phosphorylation

The effects of sulfluramide (N-ethylperfluorooctane sulfonamide) and perfluorooctane sulfonamide (DESFA) on isolated rabbit renal cortical mitochondria (RCM) were examined. Sulfluramid (1-100 microM) and DESFA (0.5-50 microM) increased state 4 respiration of RCM respiring on pyruvate/malate or succinate in a concentration dependent manner in the absence of a phosphate acceptor. In addition, both sulfluramid and DESFA increased state 4 respiration in the presence of oligomycin, an inhibitor of F0F1-ATPase. The effects of sulfluramid (200 microM), DESFA (100 microM), and the known protonophore and uncoupler of oxidative phosphorylation, carbonyl cyanide p-trifluoromethoxyphenylhydrazone (FCCP) (1 microM), on RCM proton movement were examined directly by monitoring extramitochondrial pH and indirectly by monitoring passive mitochondrial swelling. Immediately upon addition, DESFA and FCCP, but not sulfluramid, dissipated the RCM proton gradient and caused RCM to swell in solutions of NaCl or NH4Cl. These results show that DESFA uncouples oxidative phosphorylation by acting as a protonophore. RCM were shown to metabolize sulfluramid to DESFA which suggests that the increase in state 4 respiration observed with sulfluramid is due to DESFA. DESFA is unique in that it is one of two uncouplers that does not contain a ring structure and thus may be a useful model in the study of oxidative phosphorylation.     

The immunostimulating properties of cholecystokinin octapeptide and its fragments]

Immunostimulating properties of cholecystokinin octapeptide (CCK-8) were evaluated in experiments on adult normal and thymectomized mice, in vitro. It was shown that CCK-8 stimulates IgM-PFC production to SRBC, but does not change the immune response to Vi-antigen. CCK-8 increases the number of Thy-I+ spleen T cells and restores thymus-dependent immune response in thymectomized mice. CCK-8 has no effect on neutrophil phagocytosis activity in vitro. The immunostimulating activity of CCK-8 is related mainly to C-terminal fragment (identical to pentagastrin tetrapeptide) since the N-terminal CCK-8 tetrapeptide displays negligible effect in all tests.