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Acta Biologica Hungarica
Authors:
Márta Kotormán
,
Alexandra Varga
,
Phanindra Babu Kasi
, and
János Nemcsók

During the study of inhibition of amyloid fibril formation, α-chymotrypsin protein was developed in 55% ethanol at pH 7.0. We investigated the inhibitory effect of different spices on amyloid fibril formation using turbidity measurements and Congo red binding assays. We found that all spices except the black pepper and caraway seed prevented fibril formation. The highest inhibition was measured with the clove, which reduced the amount of aggregates by 90%. We studied the inhibitory effect of the cloves at different concentrations on aggregation, it was found that the inhibitory activity of clove is dependent on concentration. We have measured the total phenolic content of the spice extracts too. Based on all these findings we have come to the following conclusion: Our results indicate that spices can contain other compounds too – not only phenolic compounds – which influence the formation of amyloid fibrils, and the effectiveness of various phenolic compounds are different.

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Cereal Research Communications
Authors:
István Fekete
,
Csaba Varga
,
Zsolt Kotroczó
,
Zsolt Krakomperger
, and
János Tóth
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The presence of double-stranded RNA (dsRNA) elements in Fusarium culmorum and F. graminearum isolates of different origin, and the possible effect of these elements on pathogenicity and toxin production of the isolates were examined. Altogether 40 F. culmorum and 38 F. graminearum isolates were involved in this study, together with F. cerealis and F. pseudograminearum strains. Double-stranded RNA elements indicative of mycovirus infection were detected for the first time in 5 F. culmorum isolates. The isolates originated from the United States, The Netherlands, Australia and Israel. The dsRNA nature of the fragments was proved by RNase, DNase and S1 nuclease treatments. The sizes of the dsRNA elements varied between 0.6–3.95 kbp. A dsRNA element of 3.0 kbp in size was also detected in a F. graminearum isolate came from South Africa. None of the Central-European isolates examined were found to carry such elements. We also examined the mycotoxin producing abilities and pathogenicity of the dsRNA infected isolates. Four of the mycovirus infected F. culmorum isolates produced deoxynivalenol and zearalenone (chemotype I), while one of the isolates came from the USA produced nivalenol and fusarenone X (chemotype II). The dsRNA-containing F. graminearum isolate produced deoxynivalenol and zearalenone. In general, dsRNA-containing isolates were found to be as pathogenic to two wheat cultivars as dsRNA free isolates. RAPD analysis and sequence analysis of a putative reductase gene fragment indicated that dsRNA-containing isolates are scattered among dsRNA free isolates. Further work is in progress in our laboratory to characterize these dsRNA elements by sequence analysis.

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Cereal Research Communications
Authors:
Beáta Tóth
,
János Varga
,
Ágnes Szabó-Hevér
,
Szabolcs Lehoczki-Krsjak
, and
Ákos Mesterházy

Fusarium head blight caused mainly by Fusarium graminearum and F. culmorum is the most important disease of wheat in Central Europe. While F. graminearum is homothallic, no sexual cycle has been observed in F. culmorum . Knowledge regarding the species distribution and population structure of these pathogens is important to estimate their significance for breeding. There are two fundamental means by which fungi and other organisms transmit genes to the next generation: through clonal reproduction or by sexual recombination. To clarify the population structures of F. culmorum and F. graminearum in Central Europe, RAPD and IGS-RFLP data sets of the isolates were subjected to both the index of association tests and tree length tests. Our data indicate that the world-wide F. graminearum and F. culmorum populations have recombining structures, while both the Hungarian F. culmorum and F. graminearum populations reproduce clonally. The frequent occurrence of F. graminearum perithecia on corn residues indicates that this species undergoes a sexual cycle. Both mating type genes have been identified in each examined F. graminearum isolate, while the heterothallic distribution of mating type genes in F. culmorum indicates that this species lost its sexual cycle relatively recently.

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Acta Biologica Hungarica
Authors:
Nikolett Baranyi
,
Daniela Jakšić Despot
,
Andrea Palágyi
,
Noémi Kiss
,
Sándor Kocsubé
,
András Szekeres
,
Anita Kecskeméti
,
Ottó Bencsik
,
Csaba Vágvölgyi
,
Maja Šegvić Klarić
, and
János Varga

The occurrence of potential aflatoxin producing fungi was examined in various agricultural products and indoor air in Central European countries including Hungary, Serbia and Croatia. For species identification, both morphological and sequence based methods were applied. Aspergillus flavus was detected in several samples including maize, cheese, nuts, spices and indoor air, and several isolates were able to produce aflatoxins. Besides, three other species of Aspergillus section Flavi, A. nomius, A. pseudonomius and A. parasiticus were also isolated from cheese, maize and indoor air, respectively. This is the first report on the occurrence of A. nomius and A. pseudonomius in Central Europe. All A. nomius, A. pseudonomius and A. parasiticus isolates were able to produce aflatoxins B1, B2, G1 and G2. The A. nomius isolate came from cheese produced very high amounts of aflatoxins (above 1 mg ml–1). All A. nomius, A. pseudonomius and A. parasiticus isolates produced much higher amounts of aflatoxin G1 then aflatoxin B1. Further studies are in progress to examine the occurrence of producers of these highly carcinogenic mycotoxins in agricultural products and indoor air in Central Europe.

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