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Summary  

The adsorption kinetics of strontium ion was studied on seven natural clay samples with radioactive tracer method. The kinetic curves were determined and the kinetic data were evaluated by forms of first-rate kinetic equations with different terms, generally used for adsorption of ions of low concentration. The adsorption process was reduced to two steps. Film diffusion and participle diffusion were found in the case of five samples. Gel diffusion, film diffusion and participle diffusion were found in the case of the other two samples. The presence of significant amount of cristobalite can explain the gel phase in these two samples. The rate coefficients of steps were calculated from the kinetic curves.

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In vitro shoot multiplication of Telekia speciosa (Schreb.) Baumg. was tested on media containing benzyladenine, benzyladenine riboside, kinetin, zeatin, meta-topolin or 2-isopentenyladenine in different concentrations. We observed the proliferation rate, the length of shoots, rate of callus formation, and the presence of the hyperhydricity. The highest proliferation rate (13.17) was obtained on medium supplemented with 5.0 μM benzyladenine, however, the leaves were hyperhydrated at this concentration of benzyladenine, therefore for shoot multiplication lower (1.0 μM BA) concentration of benzyladenine is suggested. The longest shoots were achieved using 1.0 μM 2-iP. At this treatment 100% rooting was found, therefore the stage of rooting is omissible using 1.0 μM 2-iP during the multiplication. This in vitro propagation protocol should be useful for conservation as well as mass propagation of this plant species.

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The carbon balance of the sandy pasture (Bugac) and the mountain meadow (Mátra) varied between −171 and 96 gC m−2 year−1, and −194 and 14 gC m−2 year−1, respectively, during the study period (2003–2009). Large part of interannual variability of net ecosystem exchange (NEE) was explained by the variation of the annual sum of precipitation in the sandy grassland ecosystem, while this relationship was weaker in the case of the mountain meadow on heavy clay soil. These different responses are largely explained by soil texture characteristics leading to differences in soil water contents available to plants at the two grasslands. The grassland on heavy clay soil was more sensitive to temporal distribution of rainfall for the same reason. The mountain meadow therefore seems to be more vulnerable to droughts, while the sandy grassland is better adapted to water shortage. The precipitation threshold (annual sum), below which the grassland turns into source of carbon dioxide on annual basis, is only 50–80 mm higher than the 10 years average precipitation sum. In extremely dry years (2003, 2007 and 2009), even the sandy grassland ecosystem was not stable enough to maintain its sink character.

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Twenty-seven isolates of Phytophthora infestans collected in Hungary in 2001 were tested for mating type, response to metalaxyl, isozyme geno­type at glucose-6-phosphate isomerase (Gpi) and peptidase A (Pep) loci and nuclear DNA fingerprints with probe RG57. The ratios of the mating types A1 to A2 were 5:6 and 9:7 among isolates from potato and tomato, respectively. Seventeen isolates were sensitive to metalaxyl, 1 isolate responded intermediately and 9 isolates were resistant. No novel combi­nations of isozyme alleles were found; all isolates were Gpi 100/100, and genotypes at the Pep locus were 96/96 (63%), 83/96 (11%) and 100/100 (26%). In contrast, all of the 22 RG57 fingerprints exhibited patterns that have not been reported in Hungary before. On the basis of combined traits, 22 multilocus genotypes, unnoted elsewhere in Europe, were con­struct­ed among the 27 isolates analysed. These results indicate that varia­bi­lity in the Hungarian P. infestans populations is likely due to local events (asexual and sexual interactions) rather than migration from other countries.

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Although angiogenesis is considered to be indispensable for continuous tumour growth, only very few studies have been published performing microvessel quantification during tumour progression. We mea- sured the tumour vascularity in different stages of rat pancreatic carcinogenesis induced by azaserine and promoted by raw soya flour-containing pancreatotrophic diet. Besides the tumour samples taken at 6 (atypical acinar cell nodules), 15 (adenomas) and 20 (localised adenocarcinomas) months after carcino- gen initiation, we also investigated 3 control groups: tumour-bearing host tissue of azaserine-treated rats and normal tissue of untreated rats kept on standard or pancreatotrophic diet. In contrast with the usual microvessel counting on hot spots, we determined microvascular surface density (SV) and volume den- sity (VV) by electron microscopic morphometry. There was no significant difference in these respect between the control groups. At month 6 after the azaserine induction SV and VV showed slight, non- significant decrease as compared to the host control. Both values remained unchanged until the 15th month and increased significantly by the 20th month. These results may indicate comparable growth rate of tumour and new microvessels in the premalignant stages of carcinogenesis while a more intense angio- genesis than tumour growth afterwards.

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Community Ecology
Authors: K. Pintér, Z. Barcza, J. Balogh, Sz. Czóbel, Zs. Csintalan, Z. Tuba, and Z. Nagy

Interannual variation of carbon fluxes of grasslands on sandy (5 years data) and heavy clay soils (4 years data) have been analysed. The sandy grassland was carbon sink in 3 (2004, 2005, 2006) out of the investigated 5 years. Its annual C-balance is precipitation limited, the relation seems strongly conservative, with r 2 of 0.83. More than half of the net source activity fell to the summer droughts. The heavy clay grassland was net source of carbon in one year (2007) only with no whole year record from 2003, a drought and heat wave year. Dependence of the C-balance on precipitation was somewhat weaker (r 2 =0.57) than in the sandy grassland. Length of growing period showed less variation here compared to the sandy grassland. Recovery of sink activity after rains was much slower for the heavy clay grassland than for the sandy grassland. The reason behind is that the amount of water required to reach optimal soil water content for plant functioning is several times larger for the mountain grassland. This fact and the low conductivity of the clay soil for water decrease the heavy clay grassland’s recovery potential after droughts. Owing to these soil characteristics, the clay grassland may be more vulnerable to droughts in terms of decreased C-assimilation and (soil) carbon losses under the predicted drier summers even if the annual precipitation sum was higher by 10.7% on average for the mountain compared to the sandy grassland. The annual precipitation sum is close to the threshold, below which the grasslands may turn into source of carbon. While in one hand this can be viewed as an example of ecosystem scale adaptation to available water, drought events also involve loss of soil carbon and a potential positive feedback between source activity and decreasing net primary production, on the other.

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Cereal Research Communications
Authors: Sz. Fóti, Sz. Czóbel, J. Balogh, J. Nagy, A. Juhász, Z. Nagy, S. Bartha, and Z. Tuba
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Studies involving morphological description with both dominant (RAPD) and codominant (SSR, isoenzyme) molecular markers were made on 28 maize inbred lines of known genetic background with a final aim of prediction of heterosis. The genetic distance and degree of relationship between the lines was determined using cluster analysis. Only a very limited extent of allele polymorphism could be detected in isoenzyme analyses as the 28 lines formed only 16 gel electrophoretic groups, indicating that certain lines had identical isoenzyme patterns. On the basis of RAPD and gene-specific microsatellite (SSR) markers, however, all the lines could be distinguished from each other. When the lines were grouped according to genetic background it was found that although the individual marker systems only partially reflected the actual relationships between the lines, a joint processing of the data, supplemented with morphological data, revealed a close correlation between the groups formed on the dendrogram and the genetic background.

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Abstract

Epidemics and pandemics have happened throughout the history of mankind. Before the end of the 20th century, scientific progress successfully eradicated several of the pathogens. While no one has to be afraid of smallpox anymore, there are some new pathogens that have never caused human disease before. Coronaviruses are a family of enveloped RNA viruses. In the 21st century, three of them have caused serious pandemics, including severe acute respiratory syndrome in 2002 and Middle East Respiratory Syndrome in 2012. In 2019 severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) caused the coronavirus disease-19 (COVID-19) pandemic, which has destroyed hundreds of thousands of lives and continues to rage.

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Remnants of the former semiarid forest-steppe vegetation of Hungary are suspected to undergo degradation processes because of recent land-use changes. Secondary succession towards closing of the vegetation starts with shrub invasion, mainly with species of the shrub layer of loess steppe oak forest. Soil respiration (SR) activity of the intercanopy loess grassland community was followed occasionally along of six years period, as well as the spatial patterns of SR and soil water content (SWC) with three direct measuring campaigns. Dependence of SR on SWC-soil temperature was statistically significant for the six years period, but the rest of the variance should be explained by other factors, as found for normalized difference vegetation index. In the spatial analysis, significant differences were found in the ranges of semivariograms according to the seasonal variation of soil moisture content. Larger scale patches were found under summer water stress (4 m for SR, 2.6 m for SWC) and autumn senescence (3.8 m for SR, 1.3 m for SWC) periods than under well-watered, peak performance summer circumstances (0.8 m for SR, 0.6 m for SWC). This suggests that homogeneity of patterns is typical at good water supply, while coarse-grained patches prevail under drought stress.

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