Hydralazine-dependent carbon dioxide free radical formation by metabolizing mitochondria

The addition of hydralazine (1-hydrazinophthalazine) to rat liver mitochondria metabolizing malate/glutamate causes formation of a carbon-centered free radical which was spin-trapped with phenyl-t-butylnitrone (PBN) or dimethylpyrrolidine-N-oxide (DMPO). The coupling constants of the spin-trapped free radical were AN = 16.1, AH beta = 4.6 G for PBN and AN = 15.9, AH beta = 18.9 G for DMPO-trapped radical in aqueous solution. The spin-trapped free radical was shown to be the carbon dioxide anion free radical by independent synthesis, high pressure liquid chromatography separation, and electron paramagnetic resonance characterization. The amount of carbon dioxide anion free radical produced was absolutely dependent upon the presence of hydralazine and varied depending on mitochondrial substrate, with by far the highest amount produced by pyruvate. Studies with 13C-labeled pyruvate demonstrated that the carbon dioxide free radical came from C-1 of this compound.     

Effects of carbon dioxide on mental performance

Although elevated levels of inspired CO2 have been recorded in work situations, little is known about effects of concentrations greater than 6% on mental performance. We have measured the effects of inhaling 0, 4.5, 5.5, 6.5, or 7.5% CO2 for 20 min on normal young adults unhabituated to CO2. Performance of reasoning tasks, such as AB logic problems, was significantly slowed at the higher levels of CO2, with a threshold at end-tidal PCO2 close to 51 Torr. Accuracy of reasoning and short-term memory were not significantly affected. More prolonged studies with inhalation of 6.5% CO2 showed that after the first 10 min ventilation tended to increase, end-tidal PCO2 to fall, and slowing of reasoning to recover, but substantial decrement in performance continued for 80 min, by which time performance virtually stabilized. On return to air breathing, preexposure performance was resumed within 10 min. Also caused by 6.5% CO2 was a significant rise in subjectively assessed irritability and discomfort, with no significant change in alertness or in either registration or recall of long-term memory.     

Effects of carbon dioxide and methane on methanogenesis

Summary A mixed microbial culture, enriched from sewage sludge, was cultivated on a glucose medium in a high turbulence fermentor at constant temperature, pH and loading rate. Effects of high pCO₂ (0.95 atm) and pCH₄ (0.90 atm) were compared to those of low pCO₂ (0.05 atm) and pCH₄ (0.05 atm). Generally, rapid in creases in pCO₂ resulted in rapid decreases in methane production and, conversely rapid decreases in pCO₂ by N₂-sparging resulted in rapid increases in methane production. Decreased values of methane production were also accompanied by acetic acid accumulation. No inhibiting effects of high pCH₄ were detected. A method to obtain low pCO₂ by gas recycling combined with CO₂-absorption is proposed.     

大气二氧化碳浓度升高对植物-昆虫相互关系的影响

综述了CO2浓度升高对植物与昆虫相互关系影响的研究结果。大量研究表明,高浓度CO2对植物生理生化活动有显著的影响,植物营养物质的变化对植食性昆虫亦产生不同程度的影响,高浓度CO2条件对咀嚼式口器昆虫的取食、生长发育和生殖有不同程度的不良影响,昆虫为了获得足够的氮素营养而增加取食强度和时间,从而更易于受到天敌的攻击,这些昆虫的生长率、繁殖和生存率有下降的趋势;而对刺吸韧皮部汁液的昆虫来说,多引起种群数量增加或无显著影响。并对研究中存在的问题进行了分析,提出了今后研究的方向。     

Effects of carbon dioxide in anther cultures

In anther cultures of Anemone canadensis L., Anemone dichotoma L., Anemone hupehensis Lemoine, Clematis viticella L. and Papaver setigerum DC. a positive relationship between incubation in 2% CO₂ and the production of microspore-derived embryos was observed. In anther cultures of Nicotiana tabacum L., Anemone hupehensis and Clematis viticella a combination of cold treatment (7°C) and incubation in 2% CO₂ increased embryo production. In Anemone canadensis cold treatment increased the number of proembryos, whereas incubation in 2% CO₂ had no effect. In Anemone hupehensis 5% CO₂ increased embryo production by more than 2%. In Anemone dichotoma and Papaver setigerum 2% CO₂ was the more efficient level. CO₂ had no significant effect on pH in the culture medium in anther cultures of Anemone canadensis.     

Inhibition of carbon dioxide fixation by lead acetate in rat liver mitochondria.

These studies were undertaken to determine the mechanism by which intravenously administered lead salts inhibit hepatic gluconeogenesis. Within 1 h after the intravenous administration of lead acetate (10 mg), there is 97% inhibition of CO2 fixation in isolated rat liver mitochondria. This effect is concentration-dependent. The induction of phosphoenolpyruvate carboxykinase activity observed with starvation was also inhibited by intravenously administered lead acetate, but the activities of pyruvate kinase, glucose 6-phosphate dehydrogenase and pyruvate carboxylase were unaffected, as was the oxidation of palmitate and palmitoyl-CoA by mitochondria from Pb2+-treated animals. The addition of reduced glutathione to mitochondria from Pb2+-treated animals had no effect on the inhibited CO2 fixation. ATP concentrations in mitochondria from Pb2+-treated animals are decreased and the dose-response relationships for the effect of Pb2+ on CO2 fixation and ATP concentrations correspond. We conclude that the decrease in mitochondrial ATP in Pb2+-treated animals is probably responsible for the marked inhibition ov CO2 fixation, and hence the impairment of gluconeogenesis from alanine, lactate and pyruvate observed by others.     

大气CO2浓度升高对花蜜及传粉昆虫的影响

植物依赖昆虫传授花粉,昆虫从植物获得花粉和花蜜作为食物,两者在漫长的进化过程中形成了密切的互惠共生关系.大量研究表明,CO2浓度升高对植物花蜜的产量和组成有显著的影响.CO2浓度增加后,有花植物花蜜的产量和组分在不同物种之间的变化差异很大,即使是种内不同基因型植株的花蜜对CO2浓度增加的反应也有所不同.大部分种类花蜜的...     

Microbial inactivation and shelf life of apple juice treated with high pressure carbon dioxide

Apple juice prepared from 'Annurca' apple puree was treated with a HPCD batch system. The pH, °Brix, color parameters and microbial load of the treated apple juice were compared with those of thermally processed juice. Thermal processes were carried out at 35, 50, 65, 85°C and treatment times ranging between 10 and 140 minutes. Microbial inactivation kinetics indicated that 5-log reduction of natural flora in apple juice was achieved at 85°C and 60 minutes of treatment time for conventional thermal process and at 16.0 MPa, 60°C and 40 minutes for HPCD process. Results suggested that temperature played a fundamental role on HPCD treatment efficiency, with inactivation significantly enhanced when it increased from 35 to 60°C. Less significant was the role of the pressure at the tested levels of 7.0, 13.0 and 16.0 MPa. Also, 5-log reduction of natural flora in apple juice was obtained at lower temperatures by cyclic treatments of six compression and decompression steps. There were no significant differences between treated and untreated samples in °Brix (α = 0.05). Significant differences were detected in pH values between the untreated and HPCD treated samples (α = 0.05). There was a significant decrease in 'L*' and 'b*' values and also differences were detected in 'a*' values between the untreated and the HPCD treated samples (α = 0.05). Statistical analysis for °Brix, pH and color data showed no differences between the untreated and HPCD treated samples in the first 2 weeks of storage at 4°C. These results emphasize the potential use of HPCD in industrial applications.