Different zinc sensitivity of Brassica organs is accompanied by distinct responses in protein nitration level and pattern.

Zinc is an essential microelement, but its excess exerts toxic effects in plants. Heavy metal stress can alter the metabolism of reactive oxygen (ROS) and nitrogen species (RNS) leading to oxidative and nitrosative damages; although the participation of these processes in Zn toxicity and tolerance is not yet known. Therefore this study aimed to evaluate the zinc tolerance of Brassica organs and the putative correspondence of it with protein nitration as a relevant marker for nitrosative stress. Both examined Brassica species (B. juncea and B. napus) proved to be moderate Zn accumulators; however B. napus accumulated more from this metal in its organs. The zinc-induced damages (growth diminution, altered morphology, necrosis, chlorosis, and the decrease of photosynthetic activity) were slighter in the shoot system of B. napus than in B. juncea. The relative zinc tolerance of B. napus shoot was accompanied by moderate changes of the nitration pattern. In contrast, the root system of B. napus suffered more severe damages (growth reduction, altered morphology, viability loss) and slighter increase in nitration level compared to B. juncea. Based on these, the organs of Brassica species reacted differentially to excess zinc, since in the shoot system modification of the nitration pattern occurred (with newly appeared nitrated protein bands), while in the roots, a general increment in the nitroproteome could be observed (the intensification of the same protein bands being present in the control samples). It can be assumed that the significant alteration of nitration pattern is coupled with enhanced zinc sensitivity of the Brassica shoot system and the general intensification of protein nitration in the roots is attached to relative zinc endurance.

Comparing the effects of excess copper in the leaves of Brassica juncea (L. Czern) and Brassica napus (L.) seedlings: Growth inhibition, oxidative stress and photosynthetic damage.

Hydroponic experiments were conducted to compare the effects of excess copper (Cu) on growth and photosynthesis in young Indian mustard (Brassica juncea) and oilseed rape (Brassica napus). We compared the effects of excess Cu on the two Brassica species at different physiological levels from antioxidant levels to photosynthetic activity. Nine-day-old plants were treated with Cu (10, 25 and 50 µM CuSO4) for 7 and 14 days. Both species took up Cu from the external solution to a similar degree but showed slight root-to-shoot translocation. Furthermore, after seven days of treatment, excess Cu significantly decreased other microelement content, such as iron (Fe) and manganese (Mn), especially in the shoots of B. napus. As a consequence, the leaves of young Brassica napus plants showed decreased concentrations of photosynthetic pigments and more intense growth inhibition; however, accumulation of highly reactive oxygen species (hROS) were not detected. After 14 days of Cu exposure the reduction of Fe and Mn contents and shoot growth proved to be comparable in the two species. Moreover, a significant Cu-induced hROS accumulation was observed in both Brassica species. The diminution in pigment contents and photosynthetic efficiency were more pronounced in B. napus during prolonged Cu exposure. Based on all the parameters, B. juncea appears to be more resistant to excess Cu than B. napus, rendering it a species with higher potential for phytoremediation.

Physiological and morphological responses of the root system of Indian mustard (Brassica juncea L. Czern.) and rapeseed (Brassica napus L.) to copper stress.

Copper (Cu) is an essential microelement for growth and development, but in excess it can cause toxicity in plants. In this comparative study, the uptake and accumulation of Cu as well as the morphological and physiological responses of Indian mustard (Brassica juncea L. Czern.) and rapeseed (Brassica napus L.) roots to Cu treatment were investigated. The possible involvement of redox active molecules (reactive oxygen species and nitric oxide) and modification in cell wall structure associated with Cu-induced morphological responses were also studied. In short- and long-term treatments, B. juncea suffered more pronounced growth inhibition as compared with B. napus. In addition to the shortening of primary and lateral roots, the number and the density of the laterals were also decreased by Cu. Exposure to copper induced nitric oxide generation in the root tips and this event proved to be dependent on the duration of the exposure and on the plant species. In short- and long-term treatments, Indian mustard showed more significant activation of superoxide dismutase (SOD), inhibition of ascorbate peroxidase (APX) and oxidation of ascorbate (AsA) than B. napus. Moreover, H2O2-dependent lignification was also observed in the Cu-exposed plants. In longer term, significant AsA accumulation and callose deposition were observed, reflecting serious oxidative stress in B. juncea. Based on the morphological and physiological results, we conclude that rapeseed tolerates Cu excess better than Indian mustard.

Isohydric and anisohydric strategies of wheat genotypes under osmotic stress: biosynthesis and function of ABA in stress responses.

Changes in water potential (ψw), stomatal conductance, abscisic acid (ABA) accumulation, expression of the major genes involved in ABA biosynthesis, activities of abscisic aldehyde oxidase (AO, EC 1.2.3.1) and antioxidant enzymes were studied in two wheat cultivars with contrasting acclimation strategies subjected to medium strength osmotic stress (-0.976MPa) induced by polyethylene glycol (PEG 6000). Because the biosynthetic pathway of ABA involves multiple gene products, the aim of this study was to unravel how these genes are regulated in isohydric and anisohydric wheat genotypes. In the root tissues of the isohydric cultivar, Triticum aestivum cv. Kobomugi, osmotic stress increased the transcript levels of 9-cis-epoxycarotenoid dioxygenase (NCED) gene, controlling the rate limiting step of ABA biosynthesis. Moreover, this cultivar exhibited a higher basal activity and a higher induction of aldehyde oxidase isoenzymes (AAO2-AAO3), responsible for converting ABAldehyde to ABA. It was found that the fast activation of the ABA biosynthesis in the roots generated an enhanced ABA pool in the shoot, which brought about a faster closure of the stomata upon increasing osmotic stress and, as a result, the plants could maintain ψw in the tissues close to the control level. In contrast, the anisohydric genotype, cv. GK Öthalom, exhibited a moderate induction of ABA biosynthesis in the roots, leading to the maintenance but no increase in the concentration of ABA on the basis of tissue water content in the leaves. Due to the slower response of their stomata to water deficit, the tissues of cv. GK Öthalom have to acclimate to much more negative water potentials during increasing osmotic stress. A decreased activity of superoxide dismutase (SOD) was found in the leaves and roots of both cultivars exposed to osmotic stress, but in the roots elevated activities of catalase (CAT), peroxidase (POX), glutathione reductase (GR) and glutathione transferase (GST) were detected in the isohydric cultivar, suggesting that this genotype was more successful in the elimination of reactive oxygen species caused by the stress conditions.

[Biological significance of naturally occurring deuterium: the antitumor effect of deuterium depletion]. / A természetben megtalálható deutérium biológiai jelentosége: a deutériumdepletio daganatellenes hatása.

The concentration of deuterium is about 150 ppm (over 16 mmol/L) in surface water and more than 10 mmol/L in living organisms. Experiments with deuterium depleted water (30+/-5 ppm) revealed that due to D-depletion various tumorous cell lines (PC-3, human prostate, MDA, human breast, HT-29, human colon, M14, human melanoma) required longer time to multiply in vitro. DDW caused tumor regression in xenotransplanted mice (MDA and MCF-7, human breast, PC-3) and induced apoptosis in vitro and in vivo. Deuterium depleted water (25+/-5 ppm) induced complete or partial tumor regression in dogs and cats with spontaneous malignancies, it was registered as anticancer for veterinary use in 1999 (Vetera-DDW-25 A.U.V., 13/99 FVM). The hypodermic preparation of the registered veterinary drug was successfully tested in clinical investigations. Under the permission of the Hungarian Institute of Pharmacology (No. 5621/40/95) a randomized, double blind controlled, human Phase II clinical trial with prostate cancer was performed, in compliance with GCP principles, which exhibited a significant difference between the control and treated groups with respect to the examined parameters, median survival time and the extension of life-span. We suggest that cells are able to regulate the D/H ratio and the changes in the D/H ratio can trigger certain molecular mechanisms having a key role in cell cycle regulation. We suppose that not the shift in the intracellular pH, but the concomitant increase in the D/H ratio is the real trigger for the cells to enter into S phase. The decrease of D concentration can intervene in the signal transduction pathways thus leading to tumor regression. Deuterium depletion may open new perspectives in cancer treatment and prevention helping to increase the effectiveness of current oncotherapies.

In vitro model of neurotoxicity of Abeta 1-42 and neuroprotection by a pentapeptide: irreversible events during the first hour.

The cell biology of Alzheimer's disease (AD) is characterized mainly by the neurodegeneration caused by the beta-amyloid (Abeta) peptides and by the formation of neurofibrillary tangles. The initial events of neurodegeneration in the brain tissue include synaptic dysfunction and axonopathy. Abeta-induced axonopathy and neurite degeneration were studied in vitro on differentiated human-derived neurotypic SH-SY5Y cells. Different methods were used to investigate the mechanism of action of aggregated Abeta on neuroblastoma cells. Abeta 1-42 aggregated for 1 h induced irreversible changes in the neurite morphology. Change of tau hyperphosphorylation and cell viability (cytoplasmic redox state and active membrane uptake) was irreversible during the first hour after the addition of Abeta 1-42 to the cells. These rapid events indicate that Abeta might induce neurodegeneration even at an early stage of Abeta-cell contact. A novel pentapeptide LPYFD-amide, an analog of Soto's LPFFD, significantly decreased neurite degeneration, tau aggregation, and cell viability reduction induced by Abeta 1-42.

[Change of fibroblast calcium levels caused by beta-amyloid peptide in Alzheimer disease]. / beta-amiloid peptid okozta intracelluláris kalciumszint-változások Alzheimer-kórban szenvedó betegek fibroblastjain.

RATIONALE: beta-amyloid peptides, comprising the major neuropathological lesions of Alzheimer's disease, have been found to form depositions in various peripheral tissues, including the skin. Neurons in the disorder succumb to the altered ionic homeostasis and some other factors caused by this toxic peptide. In line with these findings, our study aimed to find differences in biochemical processes of cultured cutaneous fibroblasts derived from sporadic Alzheimer patients and from age-matched control individuals that may mirror changes in the central nervous system. METHODS: Intracellular ionic homeostasis of Alzheimer and control fibroblasts was measured in Fura-2AM-loaded human fibroblasts by dual wavelength spectrofluorimetry. RESULTS: Cells derived from Alzheimer patients exhibited lower intracellular free calcium levels as compared to the control cultures. Exposure of fibroblasts to beta-amyloid resulted in increased calcium concentrations of the control cells, but not of Alzheimer ones. CONCLUSION: Our findings indicate that Alzheimer's disease is a systemic disorder that, among others, affects the calcium homeostasis of fibroblasts. Even though it is unknown whether the diminished ionic response of Alzheimer fibroblasts is a disease or actual status marker, it could prove to be a useful model for the analysis of Alzheimer specific changes.