Sterol glycosides and cerebrosides accumulate in Pichia pastoris, Rhynchosporium secalis and other fungi under normal conditions or under heat shock and ethanol stress

The occurrence of glycolipids such as sterol glycosides, acylated sterol glycosides, cerebrosides and glycosyldiacylglycerols was examined in the three yeast species Candida albicans, Pichia pastoris and Pichia anomala, as well as in the six fungal species Sordaria macrospora, Pyrenophora teres, Ustilago maydis, Acremonium chrysogenum, Penicillium olsonii and Rhynchosporium secalis. Cerebroside was found in all organisms tested, whereas acylated sterol glycosides and glycosyldiacylglycerols were not found in any organism. Sterol glycosides were detected in P. pastoris strain GS115, U. maydis, S. macrospora and R. secalis. This glycolipid occurred in both yeast and filamentous forms of U. maydis but in neither form of C. albicans. This suggests that sterol glycoside is not correlated with the separately grown dimorphic forms of these organisms. Cerebrosides and sterol glycosides from P. pastoris and R. secalis were purified and characterized by mass spectrometry and nuclear magnetic resonance spectroscopy. The cerebrosides are beta-glucosyl ceramides consisting of a saturated alpha-hydroxy or non-hydroxy fatty acid and a Delta4,8-diunsaturated, C9-methyl-branched sphingobase. Sterol glycoside from P. pastoris was identified as ergosterol-beta-D-glucopyranoside, whereas the sterol glucosides from R. secalis contain two derivatives of ergosterol. The biosynthesis of sterol glucoside in P. pastoris CBS7435 and GS115 depended on the culture conditions. The amount of sterol glucoside in cells grown in complete medium was much lower than in cells from minimal medium and a strong increase in the content of sterol glucoside was observed when cells were subjected to stress conditions such as heat shock or increased ethanol concentrations. From these data we suggest that, in addition to Saccharomyces cerevisiae, new yeast and fungal model organisms should be used to study the physiological functions of glycolipids in eukaryotic cells. This suggestion is based on the ubiquitous and frequent occurrence of cerebrosides and sterol glycosides, both of which are rarely detected in S. cerevisiae. We suggest P. pastoris and two plant pathogenic fungi to be selected for this approach.     

Enhanced studies on the mechanism of gas selectivity and electronic interactions of SnO2/Na-ionic conductors

The selectivity of metal oxide gas sensors (MOG) can be improved significantly by forming composites with solid ionic conductor additives. First investigations were done using model composites of SnO₂/Natrium Super Ionic Conductor (NASICON) with the result of a huge sensitivity enhancement to substances ending with R–OH, R–HO or R–COOH groups and a reduction of sensitivity to other gas components. This selectivity of the new composite to those functional groups could be confirmed by catalytic conversion measurements with FTIR-spectroscopy at three gas components, respectively. The specific conductivity of the NASICON containing composites is significantly lower than that of pure SnO₂. Advanced studies show that the activation energy of the bulk-conductivity increases by approximately 30% in the presence of NASICON. In spite of high volume parts of NASICON (20%), no polarization effects were found (a complete Ohmic current–voltage behavior) and mainly the resistive part of the electrical impedance is influenced.     

全球电子废物的研究(中)

(续接本刊2007年第7期第36页)2电子废物管理方式和立法提案2.1延伸生产者责任制延伸生产者责任制(EPR)作为废物管理的新模式得以广泛推广。OECD将EPR定义为一种新的环境制度,在该制度下,生产者对其产品的责任延伸到产品销售后的整个生命周期,包括最终处置(OECD,2001)。与污染者付费原则一致,     

PLAUSIBLE APPROXIMATE REASONING

Modifications to Zadeh's theory of approximate reasoning are proposed to enhance the theory's ability to produce plausible inference results. The modifications include the introduction of a different implication definition and a certainty qualification for fuzzy propositions. Plausible reasoning is characterized by a set of reasoning patterns of practical significance. This set is then used to validate the overall approximate reasoning method.     

An image analysis method as applied to study the space-temporal evolution of waves in an annular gas-liquid flow

The secondary instability of the surface of a liquid film sheared by an intensive gas flow was first discovered using high-speed modification of the laser-induced fluorescence method. To study the space-temporal evolution of waves of different types, we used image analysis tools, in particular, the Canny method. As a result, we obtained the quantitative characteristics for both wave types and the phenomenon of the back slope instability of primary waves.     

Dysfluent reading in the absence of spelling difficulties: A specific disability in regular orthographies.

Two large studies identified substantial numbers of German-speaking children (Grade 3) with marked dissociations between reading and spelling difficulties. These dissociations were expected because German exhibits high regularity in the direction of graphemes to phonemes (forward regularity) but not in the direction of phonemes to graphemes (backward regularity). High forward regularity allows reliance on phonological processing in reading (even in advanced fluent reading), whereas low backward regularity requires reliance on orthographic memory representations in spelling. Dysfluent reading in the absence of spelling difficulties was associated only with a naming speed deficit--assessed at school entrance--but not with phonological memory or phonological awareness deficits. In contrast, a specific spelling deficit was preceded by phonological deficits. (PsycINFO Database Record (c) 2010 APA, all rights reserved)