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  • Author or Editor: G. Toldi x
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The purpose of this work was to further investigate the regulatory interplay between pyrophosphate:fructose 6-phosphate 1-phosphotransferase (PFP) and its positive effector, fructose 2,6-bisphosphate (Fru-2,6-P 2 ), in the storage organs of cold- and drought-stressed plants. Since there is no detectable cytoplasmic fructose-1,6-bisphosphatase (cytFBPase) activity in the taproots of carrot plants, PFP is the only enzyme that can replace its function when stored starch is converted to transportable sucrose. The working hypothesis was that PFP is likely to be involved in the mobilisation of energy reserves and might have a special role in storage organs such as carrot taproots upon stress. Both cold and drought stress resulted in a marked increase in the endogenous Fru-2,6-P 2 levels. It is suggested that the significant changes in photosynthate allocation are the direct results of the stimulation of PFP activity by elevated Fru-2,6-P 2 levels. PFP stimulated by Fru-2,6-P 2 operated in the gluconeogenic direction in the taproots of stressed carrot plants, whereas the glycolytic direction was dominant in the non-stressed controls. This suggests that the metabolic status determining the net activity of PFP depends on the physiological stress situation, making PFP an important sensor of environmental changes. The experimental data indicated that PFP is involved in the mobilisation of energy reserves during unfavourable environmental changes by promoting the re-synthesis of transportable sucrose in taproots.

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Acta Physiologica Hungarica
Authors: G Mészáros, Cs Orbán, A Kaposi, G Toldi, B Gyarmati, T Tulassay and Barna Vásárhelyi

Mitochondrial functions have a major impact on T-cell functionality. In this study we characterized whether mitochondrial function in the neonatal T-cells differs from that in the adult T-cells during short T-cell activation. Methods: We used fow cytometry methods to test mitochondrial mass and to monitor mitochondrial Ca2+ levels, mitochondrial potential and superoxide generation in parallel with cytoplasmic Ca2+ levels during phythohaemagglutinine-induced activation of CD4+ and CD8+ T-cells of 12 term neonates and 11 healthy adults. Results: Baseline mitochondrial mass of CD4+ and CD8+ cells was lower in the neonate than in the adult. In comparison with the adult, neonatal resting CD4+ T-cells had lower cytoplasmic Ca2+ levels and this was associated with normal activation induced Ca2+-response. During short-term activation cytoplasmic Ca2+-response was lower in neonatal than in adult CD8+ T-cells. Mitochondrial Ca2+ uptake was increased in CD4+ neonatal T cells while it decreased in CD8+ T-cells. Mitochondrial depolarization was increased in CD4+ and decreased in CD8+ neonatal T-cells compared to adults. Superoxide generation was higher and equal in neonatal CD4+ and CD8+ cells, respectively, compared to the adult ones. Conclusion: Our data suggest that neonatal T-cells exhibit marked differences in mitochondrial function and superoxide generation compared to adult T-cells.

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What is remarkable about resurrection plants is the ability of vegetative tissues (root, shoot, stem, leaves) to tolerate dehydration of the tissues and then return as functional units on rehydration. This phenomenon made resurrection plants exciting targets for molecular analysis of the poikilohydric ability and drought tolerance. The protective mechanisms of vegetative desiccation tolerance appear to involve three major components, sugars, proteins and antioxidants. According to the recent scientific consensus all three are postulated to be involved in maintaining cellular integrity during the drying phases. The aim of this review is to establish a provisional hierarchy among these stress avoiding mechanisms that are associated with desiccation tolerance. The main reason for ranking these signal metabolites and protective agents is their potential importance in practical applications. Although vegetative desiccation tolerance is a complex trait both genetically and physiologically, there are already examples where outcomes of targeted studies in resurrection plants are going to be directly utilized to engineer crop plants genetically. Here we also show that conventional genetic transformation techniques, via in vitro plant regeneration systems, still represent an unavoidable part of the high-throughput technology chain of molecular breeding.

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Cereal Research Communications
Authors: B. Purar, G. Bekavac, Đ. Jocković, É. Toldi Tóth, L. Kálmán, E. Raspudić and M. Dimitrijević

Corn reddening (CR) was observed for the first time in Serbia in 1957. After that, it occurred periodically, mainly in the region of Banat. In 2002 and 2003, a severe outbreak happened in late July / early August. Initial symptoms were the occurrence of a red-violet color on the leaves, leaf sheaths, husks and the bare portion of internodes. The symptoms typically appeared at the milk maturity stage and the discoloration was the most intensive at top leaves, around the main vein and along the edges, from leaf base to tip. Soon after the occurrence of the symptoms, the affected plants wilted, the foliage dried rapidly, the red pigmentation disappeared for a greater part and finally plant died off. The ears were underdeveloped and gummous and kernels were shriveled and unfilled.Several experiments were conducted to determine a possible connection between CR occurrence and the studied factors. Corn stunt spiroplasma was not identified in the CR-affected plants, and there was no apparent relationship between CR and soil fertility or nematode species identified in soil and plant samples. Insecticide-treated plots had lower CR incidence than untreated (control) plots, indicating that biotic factors could be involved.

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Acta Physiologica Hungarica
Authors: N. Eszes, A. Bohács, Á. Cseh, G. Toldi, A. Bikov, I. Ivancsó, V. Müller, I. Horváth, J. Rigó, B. Vásárhelyi, Gy Losonczy and Lilla Tamási

Asthmatic inflammation during pregnancy poses a risk for maternal and fetal morbidities. Circulating T cell immune phenotype is known to correlate with airway inflammation (detectable by fractional concentration of nitric oxide present in exhaled breath (FENO)) in non-pregnant allergic asthmatics. The aim of this study was to assess the relationship of peripheral T cell phenotype to FENO and clinical variables of asthma during pregnancy.We examined 22 pregnant women with allergic asthma in the 2nd/3rd trimester. The prevalence of Th1, Th2, regulatory T (Treg) and natural killer (NK) cell subsets was identified with flow cytometry using cell-specific markers. FENO, Asthma Control Test (ACT) total score and lung function were evaluated.Peripheral blood Th1, Th2, Treg, and NK cell prevalence were not significantly correlated to airway inflammation assessed by FENO in asthmatic pregnant women (all cells p > 0.05; study power > 75%). However, an inverse correlation was detected between Th2 cell prevalence and ACT total scores (p = 0.03) in asthmatic pregnancy.Blunted relationship between T cell profile and airway inflammation may be the result of pregnancy induced immune tolerance in asthmatic pregnancy. On the other hand, increased Th2 response impairs disease control that supports direct relationship between symptoms and cellular mechanisms of asthma during pregnancy.

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