Pentacyclic steroids,part XVI,studies on the total syntheses of racemic 1,6-dithiabenz[3,4]estra-3, 5(10),8,14-tetraen-17-one and its D-homo analogue

The total syntheses of racemic 1,6-dithiabenz[3,4]-estra-3,5(10), 8,14-tetraen-17-one [VII]and 1,6-dithiabenz-[3,4]-D-homoestra-3,5(10),8,14-tetraen-17a-one [IX]starting fron isothiochroman-4-one [I]are described.     

Localization of metabolites which are regulators of extracellular protease synthesis in Pseudomonas fluorescens bacteria

The effect of over forty low molecular weight substrates on the growth and synthesis of exocellular neutral proteases was studied in Pseudomonas fluorescens. Neutral exoproteases were found to be regulated enzymes. Glucose did not repress the synthesis of exocellular proteases; the regulation of their synthesis by amino acids involved the mechanism of induction. The data suggest that the primary intracellular inductors of the synthesis of exoproteases are formed for different groups of amino acids at different levels of their utilization by the cells, viz. at the level of transport and at the level of the first steps in the degradation of their carbon backbones. The paper discusses possible molecular mechanisms for integrating the signal of the primary intracellular inductors, which directly regulate the activity of the operon(s) of neutral exocellular proteases.     

Computer analysis of Feulgen hydrolysis kinetics

Summary A least squares fit of Feulgen hydrolysis time curves to the Bateman function is performed using an especially adapted parameter transformation together with a standard conjugate gradients iteration procedure. The method has been applied to a large number of measured data, and the use and limits of the computer evaluation are discussed.     

Reconfiguration of a Multi-oscillator Network by Light in the Drosophila Circadian Clock

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Groundwater promotes emergence of asporogenic mutants of emetic Bacillus cereus

Bacillus cereus is a ubiquitous endospore-forming bacterium, which mainly affects humans as a food-borne pathogen. Bacillus cereus can contaminate groundwater used to irrigate food crops. Here, we examined the ability of the emetic strain B. cereus F4810/72 to survive abiotic conditions encountered in groundwater. Our results showed that vegetative B. cereus cells rapidly evolved in a mixed population composed of endospores and asporogenic variants bearing spo0A mutations. One asporogenic variant, VAR-F48, was isolated and characterized. VAR-F48 can survive in sterilized groundwater over a long period in a vegetative form and has a competitive advantage compared to its parental strain. Proteomics analysis allowed us to quantify changes to cellular and exoproteins after 24 and 72 h incubation in groundwater, for VAR-F48 compared to its parental strain. The results revealed a significant re-routing of the metabolism in the absence of Spo0A. We concluded that VAR-F48 maximizes its energy use to deal with oligotrophy, and the emergence of spo0A-mutated variants may contribute to the persistence of emetic B. cereus in natural oligotrophic environments.     

Plant wounding affects the oviposition of Hellula undalis(F.). The impact of leaf chemistry

Crucifer specialists, such as the tropical pest Hellula undalis (F.), developed a close association to their hosts and depend on characteristic secondary plant compounds, the glucosinolates (GS), in many cases. Following tissue damage, GS undergo hydrolysis catalyzed by the enzyme myrosinase to produce a complex array of products which include isothiocyantes, cyanides, and thiocyanates depending on reaction condition and the chemical nature of the side chain. We found that mechanical plant damage to the tropical crop plant Brassica campestris L. ssp. chinensis (pak-choi) leads to increased GS content, especially of indolyl GS and affected the oviposition behaviour of H. undalis negatively. GS were detected in methanolic leaf surface extracts from intact B chinensis and Sinapis alba (L.) plants, but no hydrolysis products of GS were found in leaf extracts with methylene chloride. Furthermore, the oviposition stimulant activity of GS extracts for H. undalis was greatly reduced after hydrolysis of GS by myrosinase. These results suggest the importance of GS for inducing oviposition, thus excluding hydrolysis products as active principle. Specific produced slightly volatile hydrolysis products of GS (3-indolylmethyl-cyanide and 5-vinyloxazolidine-2-thione) reduced oviposition, when applied to the host-plant. Leaf chemistry, including volatile and non-volatile compounds, may determine oviposition in H. undalis indicating a suitable host-plant.     

The connection of visual evoked potentials with the subjective differences between emotional expressions of the "schematic face"

Human cortical visual potentials (VEP) were studied to obtain electrophysiological data concerning face discrimination and to compare them with the direct estimates of differences between faces obtained in the previous publications. The present schematic faces varied in curvature of a mouth and/or declination of eyebrows. These features determined the emotional expression of the schematic faces. We recorded the VEP as the response to the instant replacement of one schematic face (referent stimulus) by an other one (test stimulus) rather then to presentation of a single stimulus. Thus we recorded direct electrophysiological differences between schematic faces. A characteristic feature of this approach was the application of the set of functionally connected test stimuli with monotonously increasing values of differences between the referent and test stimuli. In a result of analysis the complex of components P120-N180-P230 in sites O1, O2, P3, P4, T5, T6 was described. Interpeaks amplitudes of the components shows high correlations with subjective differences between the same pairs of stimuli as well as with physical (configurative) differences between stimuli measured as the angles of lines, defining curvature of a mouth and a declination of eyebrows. The highest correlation with subjective estimates of emotional differences between faces was shown by interpeaks amplitudes N180-P230 in sites O1 and P3. In the some time the interpeaks amplitudes P120-N180 in sites O1 and T5 reflected highest correlation between configurative measures and subjective estimates of stimuli differences.