Determination of fruit origin by using 26S rDNA fingerprinting of yeast communities by PCR–DGGE: preliminary application to Physalis fruits from Egypt

The determination of geographical origin is a demand of the traceability system of import–export food products. One hypothesis for tracing the source of a product is by global analysis of the microbial communities of the food and statistical linkage of this analysis to the geographical origin of the food. For this purpose, a molecular technique employing 26S rDNA profiles generated by PCR–DGGE was used to detect the variation in yeast community structures of three species of Physalis fruit (Physalis ixocarpa Brat, Physalis pubescens L, Physalis pruinosa L) from four Egyptian regions (Qalyoubia, Minufiya, Beheira and Alexandria Governments). When the 26S rDNA profiles were analysed by multivariate analysis, distinct microbial communities were detected. The band profiles of Physalis yeasts from different Governments were specific for each location and could be used as a bar code to discriminate the origin of the fruits. This method is a new traceability tool which provides fruit products with a unique biological bar code and makes it possible to trace back the fruits to their original location. Copyright © 2009 John Wiley & Sons, Ltd.     

ETude cinetique des systemes Cd---Cd(II) et Fe(II)---Fe(II) en milieu aqueux par trace d'oscillogrammes lineaires au moyen de la methode de double impulsion potentiostatique

The principle and construction of a quadratic function generator are described. The voltage output, supplying the oscilloscope time-base, gives a linear i(√t) oscillogram and allows the transfer cd i_a to be read on the oscilloscope screen.

The kinetic parameters of the Cd---Cd(II0 and Fe(II)---fe(III) sytsems are determined in this way. In these two examples, the second Fick equation is solved numerically in order to establish the validity of the formula used to calculate T₀, the time corresponding to the cd i_a.

Zusammenfassung

Man beschreibt die Einstellung von einem Quadratischfunktiongenerator. Wenn die Klemmenspannung dieses Generators mit der Zeitablenkung des Oszillographes angeschaltet wird, erreicht man ein lineares Oszillogramm i(√t); die Durchtrittstromdichte i_a wird sofort auf dem Oszilloskopschrim gelesen.

Mann kann mit dieser Methode die elektrolytischen Konstanten der Reaktionen Cd---Cd(II) und Fe(II)---Fe(III) bestimmen. Jedenfalls integriert man die Zweite Diffusion differentialgleichung zahlenmässig und so, kann man die Richtigkeit der die Zeit gebenden Formel, welcher Zeit die Ordinate i_a auf die Linie i(√t) entspricht, bestätigen.     

Involvement of residues 296-299 in the enzymatic activity of tissue-type plasminogen activator

The tetra-alanine substitution variant KHRR 296–299 AAAAof tissue-type plasminogen activator (t-PA) was previously shownto have enhanced fibrin specificity and enhanced activity inthe presence of fibrin compared with the wild-type form of themolecule. The structural requirements for these alterationsin enzymatic activity were investigated by constructing severalamino acid substitution variants at each of the positions from296 to 299 and evaluating their activities under a variety ofconditions. Effects on plasminogen activator activity were commonamong the point mutants at positions 296–299; nearly allhad a phenotype similar to the KHRR 296–299 AAAA variant.The greatest effects on enzymatic function were found with multiplesubstitution variants, but some single charge reversals andproline substitutions had substantial effects. The enhancedfibrin specificity of KHRR 296–299 AAAA t-PA results inless fibrinogenolysis than seen with wild-type t-PA. Approximatelyfour times greater concentration of KHRR 296–299 AAAAcompared with wild-type t-PA was required to consume 50% ofthe fibrinogen in human plasma.     

Stability analysis of thermo-bioconvection in suspensions of gravitactic microorganisms in a fluid layer

In this paper, we investigate the effect of heating or cooling from below on the stability of a suspension of motile gravitactic microorganisms in a shallow fluid layer. The linear perturbation theory is used to obtain the stability diagram and the critical conditions for the onset of convection. It is found that the thermo-effects may either stabilize or destabilize the suspension, and decrease or increase the wavelength of the bioconvective pattern.     

Intelligible Crosstalk Between Two FDM/FM Carriers Accessing Double Cascaded Nonlinear Amplifiers

A method of evaluating double intelligible crosstalk between two frequency division multiplexed frequency modulated (FDM/FM) carriers accessing the same earth station high-power amplifier (HPA) and satellite transponder traveling wave tube amplifier (TWTA) has been developed. The analysis takes into consideration the AM/AM and AM/PM characteristics of the two cascaded memoryless nonlinear amplifiers, and the amplitude and group delay variations of transmission paths preceding the first nonlinear amplifier and of the path between the two nonlinear amplifiers. Results of the double intelligible crosstalk evaluation show the existence of significant distortion cross terms caused by the two cascaded nonlinearities and filters, in addition to individual distortion terms by each nonlinearity. Specific illustrative examples are discussed, and some practical suggestions are given for controlling crosstalk impairment effects in satellite channels with double cascaded nonlinear amplifiers.     

Reviews

LAND INTO LANDSCAPE by John M. Hunter, George Godwin/Longmans, 1985, 182 pp, £25.00

EATON ESTATE: LANDSCAPE CONSERVATION PLAN: Abridged Version of the Landscape Consultants' Report by Ian Laurie et al, Department of Town and Country Planning: University of Manchester, 1983.

DISCOVERING THE VERNACULAR LANDSCAPE by John B. Jackson, 165 pages, Yale University Press, 1984, $16.50.

THE ECOLOGICAL IMPACTS OF OUTDOOR RECREATION ON MOUNTAIN AREAS IN EUROPE AND NORTH AMERICA edited by N. G. Bayfield and G. C. Barrow. Published by Recreation Ecology Research Group 1985, Report No. 9.     

Simulation of the High-Frequency Response of a Heterogeneous Ground through the Finite Difference Technique

To simulate the propagation of an electromagnetic plane wave in an inhomogeneous ground, the finite difference approach can be used. One of the main problems in using this method is imposing the boundary conditions near the ground surface, especially at high frequency. Indeed, for the E polarization, the upper top of the numerical grid must be sufficiently far away from the air-ground interface in order to neglect the field due to the heterogeneities and the discretization of the atmosphere is necessary. For magneto-telluric modeling, improved boundary conditions have already been proposed. This paper deals with a new condition, valid everywhere in air and which can be applied for E and H polarization. Thus even at high frequency, as for radar applications, only one line is added to the grid discretizing the ground.     

Desiccant solar air conditioning in tropical climates: I—Dynamic experimental and numerical studies of silicagel and activated alumina

This paper presents a dynamic study of moist air dehumidification in view of its use in an air conditioning process by evaporative cooling in tropical climates. A special device has been built to study dehumidification of tropical-like inlet air, through a fixed compact bed of silicagel and activated alumina. The compact desiccant storage is composed of two parallel beds to reduce the pressure drop. A good agreement is obtained for our experiment, and the computed amount of cycled water from the numerical model in the adiabatic process. This analytical model is used to simulate a complete air conditioning open cycle operating with hot and humid air.