Ochratoxin A Production by Aspergillus ochraceus Wilhelm Grown Under Controlled Atmospheres

[This corrects the article on p. 1136 in vol. 45.].     

Effects of Controlled Atmospheres on Production of Sesquiterpenoid Stress Metabolites by White Potato Tuber: Possible Involvement of Cyanide-resistant Respiration

Levels of katahdinone (solavetivone), lubimin, rishitin, and phytuberin, sesquiterpenoid stress metabolites of white potato (Solanum tuberosum), were monitored in tuber slices which were challenged with an extract of Phytophthora infestans and incubated under controlled atmospheres. A mixture of ethylene in air enhanced stress metabolite production. This enhancement was amplified by higher partial pressures of oxygen. Stress metabolite production was inhibited by salicylhydroxamic acid. These results suggest the involvement of cyanide-resistant respiration in the production of potato stress metabolites, compounds which may serve as phytoalexins.     

高O2或高CO2浓度气调贮藏对“那翁”甜樱桃采后生理和贮藏性的影响

研究了甜樱桃品种“那翁”（Prunus avium L.cv.Napoleon)在1℃的高O2浓度气调（CA－1：70％ O2＋0％,CO2）,高CO2浓度气调（CA－II：5％ O2＋10％ CO2）,自发气调（modified atmosphere package,MAP)和普通冷藏条件下果实生理,品质,耐藏性的变化,结果表明：与其他处理相比,高O2浓度的气调可以抑制果实腐烂,减少果肉中乙醇含量,但果实的丙二醛（MDA）含量迅速上升,褐变严重,高CO2浓度的气调能有效抑制MDA含量上升的速率和多酚氧化酶（PPO）活性,保持果实硬度和维生素C含量,减少果实腐烂和褐变,延长贮藏寿命,不同处理对果实可溶性固形物含量的影响不大。“那翁”甜樱桃在5％ O2＋10％ CO2气调中贮藏80d能保持果实固有的风味品质。在MAP下,70％O2＋0％CO2和普通冷藏中的适宜贮藏期分别为40d,20d和30d。     

高O2或高CO2浓度气调贮藏对"那翁"甜樱桃采后生理和贮藏性的影响

研究了甜樱桃品种"那翁" ( Prunus avium L. cv. Napoleon)在1 ℃的高O2 浓度气调(CA-I: 70% O2+0% CO2)、高CO2 浓度气调 (CA-II: 5% O2+10% CO2)、自发气调 (modified atmosphere package, MAP) 和普通冷藏条件下果实生理、品质、耐藏性的变化.结果表明:与其他处理相比,高O2 浓度的气调可以抑制果实腐烂、减少果肉中乙醇含量,但果实的丙二醛(MDA)含量迅速上升、褐变严重.高CO2浓度的气调能有效抑制MDA含量上升的速率和多酚氧化酶(PPO)活性,保持果实硬度和维生素C含量,减少果实腐烂和褐变,延长贮藏寿命.不同处理对果实可溶性固形物含量的影响不大."那翁" 甜樱桃在5% O2+10% CO2气调中贮藏80 d能保持果实固有的风味品质.在MAP下, 70% O2+0% CO2和普通冷藏中的适宜贮藏期分别为40 d、20 d和30 d.     

固相微萃取-气质法测定土壤挥发性抑菌物质

运用固相微萃取．气相色谱,质谱法(SPME-GC／MS),测定了参与土壤抑真菌作用的土壤挥发性成分和土壤细菌挥发性代谢物。通过比较土壤来源和土壤细菌来源的挥发性抑菌成分,发现在强挥发性抑菌土壤和土壤细菌代谢物中普遍存在着三甲胺、二甲基二硫醚、3-甲基-2-戊酮、甲基吡嗪、2,5-二甲基吡嗪、N,N-二甲基辛胺、十九烷等化合物。这些化合物很有可能就是参与土壤抑菌作用,特别是挥发性物质抑菌作用的主要成分。另外,为深入了解土壤中参与抑菌作用的挥发性化合物提供了简便有效的方法。     

Pathways to Earth-Like Atmospheres

We discuss the evolution of the atmosphere of early Earth and of terrestrial exoplanets which may be capable of sustaining liquid water oceans and continents where life may originate. The formation age of a terrestrial planet, its mass and size, as well as the lifetime in the EUV-saturated early phase of its host star play a significant role in its atmosphere evolution. We show that planets even in orbits within the habitable zone of their host stars might not lose nebular- or catastrophically outgassed initial protoatmospheres completely and could end up as water worlds with CO₂ and hydrogen- or oxygen-rich upper atmospheres. If an atmosphere of a terrestrial planet evolves to an N₂-rich atmosphere too early in its lifetime, the atmosphere may be lost. We show that the initial conditions set up by the formation of a terrestrial planet and by the evolution of the host star’s EUV and plasma environment are very important factors owing to which a planet may evolve to a habitable world. Finally we present a method for studying the discussed atmosphere evolution hypotheses by future UV transit observations of terrestrial exoplanets.     

Effects of Hypobaric and Hyperbaric Helium Atmospheres on the Growth of Chlorella sorokiniana

Growth of Chlorella sorokiniana is unaffected by the choice of atmospheric diluent gas. Reduced total pressure has no inhibitory effect and may be slightly stimulatory.     

Vitamin K5 as a Fungistatic Agent

The effectiveness of vitamin K(5) in controlling the growth of different molds at varying pH levels in a culture medium, in tomato juice, and in several berry purees was studied. The molds studied were Aspergillus, Botrytis, Hormodendrum, Mucor, and Penicillium. The results showed that vitamin K(5) was effective as a fungistatic agent at concentrations ranging from 0.006 to 0.02%.     

Fungistatic activity of different Indian soils againstFusarium udum Butler

Summary The fungistatic activity of different Indian soils againstF. udum, causing wilt disease of pigeon-pea, has been assessed in relation to soil pH and organic matter. Correlation co-efficient between soil characteristics and fungistasis has been calculated to evaluate relationship. High fungistatic activity was exhibited generally by the soils having low pH but high organic matter. The soils exhibiting high fungistatic activity againstF. udum have low incidence of wilt disease of pigeon-pea. There was no definite correlation between volatile and non-volatile fungistasis and, therefore, the origins of volatile and non-volatile fungistasis are different. In the usual biological limit pH had insignificant impact on fungistasis.     

Fungistatic Activity of Essential Oils from Ocimum basilicum Chemotypes

Essential Oils from Ocimum basilicum and their components showed different inhibition effects against Fusarium oxysporum f. sp. vasinfectum and Rhizopus nigricans, The different antifungal activity of the essential oils is determined mainly by the percentage of the main components: cineol, linalool, methylchavicol and eugenol.     

Fungistatic activity of Semecarpus anacardium Linn. f nut extract

Alcoholic extract of dry nuts of S. anacardium showed dose dependent antifungal activity in vitro against Aspergillus fumigatus and Candida albicans. At 400 mg/ml concentration, growth of both the fungi was inhibited and considerable reduction in size of cells and hyphae was observed. Sporulation also decreased.     

Mechanism of Runaway Electron Generation at Gas Pressures from a Few Atmospheres to Several Tens of Atmospheres

The mechanism of runaway electron generation at gas pressures from a few atmospheres to several tens of atmospheres is proposed. According to this mechanism, the electrons pass into the runaway mode in the enhanced field zone that arises between a cathode micropoint—a source of field-emission electrons—and the region of the positive ion space charge accumulated near the cathode in the tails of the developing electron avalanches. As a result, volume gas ionization by runaway electrons begins with a time delay required for the formation of the enhanced field zone. This process determines the delay time of breakdown. The influence of the gas pressure on the formation dynamics of the space charge region is analyzed. At gas pressures of a few atmospheres, the space charge arises due to the avalanche multiplication of the very first field-emission electron, whereas at pressures of several tens of atmospheres, the space charge forms as a result of superposition of many electron avalanches with a relatively small number of charge carriers in each.