Authors:J. Varga, S. Kocsubé, Z. Koncz and J. Téren
Ochratoxin A is a mycotoxin produced by Aspergillus and Penicillium species. This mycotoxin is a common contaminant of various foods including cereal products, spices, dried fruits, coffee, beer and wine. Besides cereal products, goods of grape origin contribute significantly to ochratoxin exposure of humans. The ochratoxin content and mycobiota of raisins purchased in Hungarian outlets were examined in this study. Ochratoxin A content was examined by an immunochemical technique, and the results were confirmed by HPLC analysis using fluorescent detection. Altogether 20 raisin samples were analyzed. Ochratoxin A was detected in all but two samples with ochratoxin concentrations ranging from 0 to 6.2 mg kg-1. The most heavily contaminated raisin sample came from Iran. However, none of the raisins contained ochratoxin A above 10 mg kg-1, the European Community maximum allowable limit in raisins. The mycobiota of raisin samples was also examined to clarify which species could be responsible for ochratoxin A contamination. All except three raisin samples were contaminated with black aspergilli, some of which produced ochratoxin A. Besides A. carbonarius, ochratoxin producing A. tubingensis isolates dominated in the samples.
Authors:Á. Kovács, R. Dulicsek, L. Varga, J. Szigeti and Z. Herpai
Thirty-three varieties of dairy products were analysed for fat and cholesterol contents, and a high correlation (r=0.983) was found between these two compositional attributes. Cholesterol concentration was independent of processing factors such as heat-treatment of the raw material, use of starter culture, type of the starter organisms employed and whipping or flavouring of the product. The non-fat varieties of fluid, fermented and dried milks showed significantly increased cholesterol-to-fat ratios compared to the other products tested because they contained considerable amounts of small fat globules and, therefore, had a large surface area with cholesterol bound to the fat globule membranes. The results of this study may be useful when establishing dietary guidelines for the general public according to health concerns, when formulating diets for population groups with special requirements or when assessing fat and cholesterol intakes in epidemiological studies aimed at investigating the relationship between diet and health.
Authors:G. Fekete, Zs. Molnár, E. Magyari, I. Somodi and Z. Varga
In this paper, we elaborated a new concept (the Regularities-Deviations-Uniqueness; RDU framework) to analyse regional vegetation patterns and applied it to the Pannonian region of the Carpathian Basin. We introduced three criteria, namely: distributional regularity, distributional deviation, and compositional uniqueness. Regularities conform to the pattern expected based on macroclimate and relief. Deviations are singular phenomena and are defined as the conspicuous departures from the regular pattern at odds with either zonal pattern (climate rules), or the repetitive extrazonal patterns (relief and meso-climate interactions). Endemic plant communities of the Pannonian region (defined by a unique species composition) are regarded as the unique features. The main regularities recognised for the Pannonian region are: (1) the altitudinal pattern of vegetation belts, (2) the horizontal zonation of the Dunántúl, (3) the gradient of continentality along the mountain ranges, and (4) the circular zonality of the Nagyalföld. Deviations are mostly explained by local vegetation history, mesoclimate, and edaphic factors. The major deviations include (i) occurrence of mixed Pinus sylvestris forests in Őrség, (ii) cool continental forest-steppe forests on Kisalföld, and Gödöllői-dombvidék, (iii) the direct contact of Fagus and Quercus pubescens forests (Bakony, Balatonfelvidék), (iv) the Fraxinus excelsior-Tilia spp. forests on rock outcrops, and (v) the Sphagnum bogs on the Alföld. Individuality of the Pannonian region is demonstrated by the endemic zonal forest-steppe forests and intrazonal endemic communities such as the Cerasus mahaleb-Quercus pubescens forests, and the vegetation on calcareous sand, dolomite and saline soils and the like. We argue that the introduced criteria are suitable for the entitation and description of other biogeographical regions, and offer useful tool for interregional comparisons.
Authors:K. Radó, Z. Németh, K. Varga, J. Schunk and F. Kőrösi
the period of 1993-2001 chemical decontaminations of 24 SGs in the units 1-3 of
the Paks NPP were carried out by a non-regenerative version of AP-CITROX
technology, even in two or three consecutive cycles. A comprehensive
investigation of the above decontamination method have revealed that the
fundamental issues of analytical chemistry and corrosion science were not taken
into consideration during the elaboration of AP-CITROX procedure. Therefore,
the non-regenerative version of the technology utilized at Paks NPP can be
considered to be not an adequate method for the chemical decontamination of any
reactor equipments having large steel surfaces (e.g., SGs). As a consequence of
the lack of the appropriate decontamination method, initiation of a R&D project
focused on the elaboration of the required technology should not be postponed.
In this paper, we present a brief overview on the fundamental issues of the
technology development. Selected findings obtained in our laboratory on
the field of the improvement of the AP-CITROX technology are also reviewed in
order to demonstrate the crucial role of some selection criteria.
Authors:E. Besenyei, P. G. Ott, Z. Bozsó, A. Czelleng, Á. Szatmári, G. J. Varga and Z. Klement
The development of local early basal resistance (EBR), is a form of non-specific general defence response of plants to bacteria, greatly depending on temperature. This symptomless defence mechanism is easily detected by its inhibitory action on the hypersensitive response (HR) caused by a subsequent incompatible pathogenic bacterium. Both EBR and HR were investigated at different temperatures ranging from 30 °C to 5 °C. At normal temperatures (30-20 °C) both heat-killed Pseudomonas syringae pv. syringae 61 (polyvirulent to many plants) and Pseudomonas savastanoi pv. phaseolicola S21 (pathogenic to bean) induced EBR in tobacco leaves within a few hours, but below 10 °C it was greatly delayed and at 5 °C usually no EBR response could be detected within 2-3 days. The time required for development of EBR did not depend on the bacterial pathovars or strains. However, the induction time of HR was not as sensitive to low temperatures as that of EBR, instead, it depended on the bacterial pathovars used.
Authors:Z. Wéber, Z. Bus, K. Gribovszki, B. Süle, Gy Szeidovitz and P. Varga
In this paper, research activities at the Theoretical Division of the Seismology Department of GGRI (in short: Seismological Observatory) are summarized. The reported investigations have been carried out since 1999, when the division was founded with three members. Detailed discussions of the presented results can be found in various national and international scientific journals.
Authors:K. Varga, Z. Németh, J. Somlai, I. Varga, R. Szánthó, J. Borszéki, P. Halmos, J. Schunk and P. Tilky
During the optimization of the AP-CITROX decontamination technology the effect of the different flow rates of the decontamination solutions on the radioactive contamination and corrosion state of stainless steel tube samples originating from steam generators of Paks NPP were studied by a pilot-plant circulation system. The results have proved that a significant increase (up to 2.89 m/s) in the flow rate of the decontamination solution in the 1-5 steps is highly recommended and in order to improve the passivity of the surfaces it should be kept as low as possible (0.5 m/s) during the passivation.
Authors:A. A. Czelleng, Z. Bozsó, P. G. Ott, E. Besenyei, G. J. Varga, Á. Szatmári, Y. M. Hafez and Z. Klement
Pseudomonas viridiflava is an opportunistic, post-harvest pathogenic bacterium that causes soft rot of fruits and vegetables. In vivo expression technology was used to identify genes that participate in the pathogenicity of P. viridiflava. Genetic loci that are induced in planta were identified. Ten such loci were partially sequenced and annotated. Here we describe five of them, which influence the pathogen's stress tolerance in planta. Three of the identified ORFs that show sequence identity to known genes encode membrane proteins, the remaining two encode enzymes in catabolic pathways.
Authors:J. Varga, Z. Koncz, S. Kocsubé, T. Mátrai, J. Téren, V. Ostry, J. Skarkova, J. Ruprich, A. Kubatova and Z. Kozakiewicz
Ochratoxin A is a mycotoxin produced by
species. This mycotoxin is a common contaminant of various foods including cereal products, spices, dried vine fruits, coffee, cocoa, beer and wine. Apart from cereal products, beer and wine contribute significantly to ochratoxin exposure of humans. In the Mediterranean region of Europe, the black
species are the sources of ochratoxin contamination of grape products. In this study, we examined the source of ochratoxin contamination of grapes in Hungary and the Czech Republic. The mycobiota of grape berries from 25 Hungarian and Czech vineyards was examined. Potential ochratoxin producing fungi were only identified in grapes from Southern Hungary. Among the 16 black
strains isolated, 12 belong to the
species, and 10 produced small amounts (1.5–10 μg kg
) of ochratoxin A in a liquid medium. We could also identify an
isolate which produced 3.5 μg kg
ochratoxin A in a liquid medium at pH 6.0. However, the amount of ochratoxin A produced was very low even in a medium which is favourable for mycotoxin production, and ochratoxin A was not detected in any of the grape juice, must and wine samples examined, indicating the absence of health hazard to costumers. Other potentially toxigenic fungi including
Aspergillus flavus, Penicillium expansum
species were also isolated. Further studies are in progress to evaluate the importance of these fungi in food safety.
Authors:A. Czelleng, Z. Bozsó, P. Ott, E. Besenyei, G. Varga, A. Szatmári, E. Szabó, L. Zsiros and Z. Klement
Compared to the known method of conjugation the frequency of transposon mutagenesis following conjugation was enhanced 11-fold by two hours of pre-incubation of recipient
1 on conjugation media. The increased frequency was ƒ = 1.3 × 10
. In other species of
high rates of transposon mutants were similarly obtained; however, in these strains the increased frequency was less than 5-fold.