scholarly journals Isoepoxydon, a new metabolite of the patulin pathway in Penicillium urticae

1979 ◽  
Vol 182 (2) ◽  
pp. 445-453 ◽  
Author(s):  
Junichi Sekiguchi ◽  
G. Maurice Gaucher
Keyword(s):  
Parent Strain ◽  
Biosynthetic Pathway ◽  
Secondary Alcohol ◽  
Antibiotic Activity ◽  
Epoxide Ring ◽  
Boat Conformation ◽  
Washed Cell ◽  
Washed Cell Suspension ◽  
Relationship Of ◽  
Better Than

A patulin-negative mutant (J1) of Penicillium urticae (N.R.R.L. 2159A) was known to accumulate about 100mg per litre quantities of the 5,6-epoxygentisyl quinone, (−)-phyllostine and another metabolite (UIII). Both were derived from acetate and hence were polyketides. Purified UIII (m.p. 53°C, [α]32D+206°, λmethanolmax. 240nm; ε 3806 litre·mol−1·cm−1) was characterized as a partially reduced derivative of (−)-phyllostine and was found to be a diastereoisomer of the known phytotoxin, (+)-epoxydon. Hence its designation as (+)-iso- or epi-epoxydon. From 1H n.m.r. and c.d. data the stereochemistry of the epoxide ring in (+)-isoepoxydon was determined to be identical with that in (+)-epoxydon (i.e. R,R) but the configuration of the secondary alcohol at C-4 was S rather than R as in (+)-epoxydon. Isoepoxydon (compound UIII) is therefore (4S,5R,6R)-5,6-epoxy-4-hydroxy-2-hydroxymethylcyclohex-2-en-1-one. The boat conformation in which the C-4 hydroxy group is axial is preferred. In the range of 1mm to 5mm, the antibiotic activity of (+)-isoepoxydon against Bacillus subtilis sp. was 56% of that obtained with patulin. Over a period of 1 to 3h, [14C]isoepoxydon was efficiently converted into patulin by a shake culture of the parent strain of P. urticae. The precursor relationship of isoepoxydon to patulin was confirmed by feeding unlabelled isoepoxydon (1mm) to a washed-cell suspension of a mutant (J2) in which, over a period of 3 to 5h, a better than 60% conversion into patulin was attained. The enzymic relationship between isoepoxydon and phyllostine and their positions in the late portion of the patulin biosynthetic pathway are discussed.

The effect of sulphadiazine, proguanil and 2:4-diamino-6:7-diisopropylpteridine upon gametocyte production inPlasmodium gallinaceum(Brumpt, 1935)

Parasitology ◽  
1954 ◽  
Vol 44 (1-2) ◽  
pp. 120-131 ◽  
Author(s):  
Ann Bishop
Keyword(s):  
Nucleic Acids ◽  
Parent Strain ◽  
Nuclear Division ◽  
Plasmodium Gallinaceum ◽  
Effective Doses ◽  
Relationship Of ◽  
The Relationship

In strains ofPlasmodium gallinaceumpassaged by blood-inoculation, through young birds treated with small, but effective doses of proguanil, sulphadiazine or 2:4-diamino-6:7-diisopropylpteridine, the numbers of gametocytes produced were much greater than in the parent strain passaged by the same method.The effect of the drugs upon gametocyte production appears to be a long term one, since no change in gametocyte numbers was observed in birds treated with proguanil or sulphadiazine for only a few days.The relationship of these drugs to nuclear division and the synthesis of nucleic acids is discussed in the light of the observed increase in gametocyte-production in drug-treated strains ofP. gallinaceum.

A Method for Bromine Determination in Wool Fabric by X-Ray Fluorescence Spectrometry

1976 ◽  
Vol 46 (6) ◽  
pp. 463-465 ◽  
Author(s):  
F. William Reuter ◽  
Geraldine E. Secor ◽  
Mendel Friedman
Keyword(s):  
Fluorescence Spectrometry ◽  
Wool Fabric ◽  
X Ray ◽  
Fluorescence Measurements ◽  
Straight Line ◽  
Bromine Concentration ◽  
Wet Chemical ◽  
Relationship Of ◽  
Line Relationship ◽  
Better Than

Bromine is measured in flame-resistant wool fabric by x-ray fluorescence spectrometry with a relative precision of 3 to 8% and relative accuracy of better than 10%. The method computes the bromine concentration from fluorescence measurements of the sample, and a thin film standard, and two measurements of attenuation by the sample. Deviations of 10 to 20% from a straight-line relationship of x-ray counts to bromine concentration are accounted for. X-ray fluorescence is generally useful for routine analyses of bromine in textiles and has advantages over wet chemical analysis.

scholarly journals Estimation of C∗-Integral for Central Cracked Plate Under Biaxial Loading

2020 ◽  
Vol 12 (07) ◽  
pp. 2050079
Author(s):  
Yanwei Dai ◽  
Fei Qin ◽  
Yinghua Liu ◽  
Weizhe Feng ◽  
Guian Qian
Keyword(s):  
Loading Condition ◽  
Biaxial Loading ◽  
Classical Method ◽  
Creep Crack ◽  
Cracked Plate ◽  
Reference Stress ◽  
Creep Time ◽  
Relationship Of ◽  
The Relationship ◽  
Better Than

The reference stress method (RSM) is a classical method to estimate [Formula: see text]-integral of creep crack. An extended reference stress method (ERSM) is given for the central cracked plate (CCP) under biaxial loading in this paper. The applicability and verification for the proposed ERSM is given. The study finds that the solutions with the proposed ERSM agree better than those of RSM under biaxial loading condition. A theoretical form to predict the relationship of [Formula: see text]-integral between biaxial loading and uniaxial loading is discussed. Relation between [Formula: see text]-integral and creep time under biaxial loading is validated and discussed.

Statistical Relationship of Morsal to Bucco-lingual, Approximal and Sulcal Caries in Rats

1979 ◽  
Vol 58 (11) ◽  
pp. 2091-2094
Author(s):  
L.A. Rinehimer ◽  
J.M. Tanzer
Keyword(s):  
Smooth Surface ◽  
Statistical Relationship ◽  
Relationship Of ◽  
Approximal Caries ◽  
Better Than

The correlation of morsal with sulcal, bucco-lingual and approximal caries scores of rats was compared. The morsal with bucco-lingual plus approximal correlation was significantly better than the morsal with sulcal correlation. When reporting rat caries, sulcal scores should be reported alone; morsal scores should be grouped with bucco-lingual and approximal to demonstrate total smooth surface lesions.

Can Wolbachia modulate the fecundity costs of Plasmodium in mosquitoes?

Parasitology ◽  
2017 ◽  
Vol 145 (6) ◽  
pp. 775-782 ◽  
Author(s):  
F Zélé ◽  
J Denoyelle ◽  
O Duron ◽  
A Rivero
Keyword(s):  
Infectious Diseases ◽  
Natural System ◽  
The Other ◽  
Mosquito Vectors ◽  
Fitness Costs ◽  
Other Hand ◽  
Reproductive Losses ◽  
Relationship Of ◽  
Better Than ◽  
Damaging Effects

AbstractVertically transmitted parasites (VTPs) such as Wolbachia are expected not only to minimize the damage they inflict on their hosts, but also to protect their hosts against the damaging effects of coinfecting parasites. By modifying the fitness costs of the infection, VTPs can therefore play an important role in the evolution and epidemiology of infectious diseases.Using a natural system, we explore the effects of a Wolbachia–Plasmodium co-infection on mosquito fecundity. While Plasmodium is known to frequently express its virulence by partially castrating its mosquito vectors, the effects of Wolbachia infections on mosquito fecundity are, in contrast, highly variable. Here, we show that Plasmodium drastically decreases the fecundity of mosquitoes by ca. 20%, and we provide the first evidence that this decrease is independent of the parasite's burden. Wolbachia, on the other hand, increases fecundity by roughly 10%, but does not alter the tolerance (fecundity–burden relationship) of mosquitoes to Plasmodium infection.Although Wolbachia-infected mosquitoes fare overall better than uninfected ones, Wolbachia does not confer a sufficiently high reproductive boost to mosquitoes to compensate for the reproductive losses inflicted by Plasmodium. We discuss the potential mechanisms and implications underlying the conflicting effects of these two parasites on mosquito reproduction.

scholarly journals A Mutation in the luxS Gene Influences Listeria monocytogenes Biofilm Formation

2006 ◽  
Vol 72 (8) ◽  
pp. 5653-5658 ◽  
Author(s):  
Shlomo Sela ◽  
Shmulik Frank ◽  
Eddy Belausov ◽  
Riky Pinto
Keyword(s):  
Listeria Monocytogenes ◽  
Biofilm Formation ◽  
Parent Strain ◽  
Vibrio Harveyi ◽  
Reporter Strain ◽  
Luxs Gene ◽  
Wild Type ◽  
Autoinducer 2 ◽  
Wild Type Phenotype ◽  
Better Than

ABSTRACT Using a Vibrio harveyi reporter strain, we demonstrated that Listeria monocytogenes secretes a functional autoinducer 2 (AI-2)-like signal. A luxS-deficient mutant produced a denser biofilm and attached to a glass surface 19-fold better than the parent strain. Exogenous AI-2 failed to restore the wild-type phenotype to the mutant. It seems that an intact luxS gene is associated with repression of components required for attachment and biofilm formation.

Spiroplasma cells utilize carbohydrates via the phosphoenolpyruvate-dependent sugar phosphotransferase system

1991 ◽  
Vol 37 (6) ◽  
pp. 477-479 ◽  
Author(s):  
Mark Tarshis
Keyword(s):  
Cell Suspension ◽  
Key Words ◽  
Direct Measurement ◽  
Phosphotransferase System ◽  
Sulfhydryl Reagents ◽  
Carbohydrate Utilization ◽  
Sugar Utilization ◽  
Washed Cell ◽  
Phosphate Donor ◽  
Washed Cell Suspension

Ten Spiroplasma species tested were found capable of fermenting glucose, mannose, fructose, and sucrose, but not ribose, maltose, 2-deoxyglucose, xylose, sorbitol, glactose, lactose, and arabinose. Sugar utilization was measured by a direct measurement of the changes in pH of a washed cell suspension upon the addition of the various sugars. Sulfhydryl reagents, uncouplers, and glycolysis inhibitors prevented the sugar-induced pH shifts. The spiroplasmas were capable of phosporylating α-methylgucoside in a reaction that required phosphoenolypyruvate, but not ATP, as a phosphate donor, suggesting that Spiroplasma species possess a phosphoenolpyruvate-dependent sugar phosphotransferase system. Key words: Spiroplasma, carbohydrate utilization, pH changes, phosphenolpyruvate-dependent sugar phosphotransferase system.

Hydrolytic enzymes of some periphytic marine bacteria

1972 ◽  
Vol 18 (9) ◽  
pp. 1483-1490 ◽  
Author(s):  
William A. Corpe ◽  
Harvey Winters
Keyword(s):  
Hydrolytic Enzymes ◽  
Intracellular Enzyme ◽  
Washed Cell ◽  
Bacterial Cultures ◽  
Cell Extracts ◽  
Cell Autolysis ◽  
Ecological Importance ◽  
Cell Envelopes ◽  
Relationship Of ◽  
Polysaccharide Hydrolase

Several periphytic marine bacterial cultures were examined for their content of hydrolytic enzymes. Quantitative assays were done for extracellular and intracellular proteinase, phosphatase, esterase, β-glucosidase, and four polysaccharide hydrolase activities. While some of the enzymes were released extracellularly by growing cells, the greatest amounts of proteinase, esterase, phosphatase, and β-glucosidase were located in the cells and released by mechanical breakage or by cell autolysis. Substantial amounts of proteinase were found in washed cell envelopes of the bacteria. All of the bacteria showed some enzymatic activity against one or more of the algal and microbial acid polysaccharides tested. Enzymes active against these polyanions were found either extracellularly or in cell extracts, depending on the culture concerned. Partial lysis of cell envelopes from two of the periphytes was produced by extracellular or intracellular enzyme mixtures. The ecological importance of bacterial hydrolases and the possible relationship of periphytic bacteria to grazing and detritus feeding invertebrates is discussed.

scholarly journals Hourly Relationship between Reference Evapotranspiration and Shoot Shrinkage in Walnut Trees and Pomegranate under Deficit Irrigation

Plants ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 31
Author(s):  
Eduardo Salgado ◽  
Nieggiorba Livellara ◽  
Esteban Chaigneau ◽  
Fernando Varas ◽  
Italo F. Cuneo
Keyword(s):  
Water Potential ◽  
Deficit Irrigation ◽  
Reference Evapotranspiration ◽  
The Novel ◽  
The Past ◽  
Slope Analysis ◽  
Daily Scale ◽  
Relationship Of ◽  
The Relationship ◽  
Better Than

Diameter fluctuations of branches, shoots, or fruits are related to plant transpiration and water potential. In the past, several models have related dendrometric variables and evapotranspiration on a daily scale. However, trunk–branch shrinkage occurs only between dawn and midday, while evapotranspiration occurs most of the day from sunrise to sunset. Previous models have failed to incorporate this key fact. The objective of the present study was to assess the relationship of hourly daily shrinkage (HDS) between dawn and the next 4 h to the hourly reference evapotranspiration (EToh) of the same period in walnut trees and pomegranate plants under different irrigation regimes. Our data show that the relationship between EToh and HDS is much better than several previous models that included maximum daily shrinkage (MDS) and reference evapotranspiration (ETo). The novel slope analysis of the relationship between HDS versus time used here corresponds to the velocity at which the HDS occurs, which depends on the ETo intensity at that moment. This new method of analyzing this type of data calls for a revision of these models and sets a new baseline for future analysis.

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