Effects of Salicylic Acid on the Metabolism of Mitochondrial Reactive Oxygen Species in Plants

Different abiotic and biotic stresses lead to the production and accumulation of reactive oxygen species (ROS) in various cell organelles such as in mitochondria, resulting in oxidative stress, inducing defense responses or programmed cell death (PCD) in plants. In response to oxidative stress, cells activate various cytoprotective responses, enhancing the antioxidant system, increasing the activity of alternative oxidase and degrading the oxidized proteins. Oxidative stress responses are orchestrated by several phytohormones such as salicylic acid (SA). The biomolecule SA is a key regulator in mitochondria-mediated defense signaling and PCD, but the mode of its action is not known in full detail. In this review, the current knowledge on the multifaceted role of SA in mitochondrial ROS metabolism is summarized to gain a better understanding of SA-regulated processes at the subcellular level in plant defense responses

Ethylene-regulated reactive oxygen species and nitric oxide under salt stress in tomato cell suspension culture

In the present work the role of ethylene (ET) in the accumulation of reactive oxygen species (ROS) and nitric oxide (NO) was investigated under the effect of sublethal (100 mM) and lethal (250 mM) concentrations of NaCl in tomato cell suspension culture. In these cultures the salt stress increased the production of ET and ROS after 6 hours but NO level was enhanced only at 100 mM NaCl. This corresponded with the lower ratio of dead cells (20%) in these samples suggesting that NO functioned as a protecting compound under moderate salt stress. The synthesis of ET was further enhanced by the addition of ET precursor, 1-aminocyclopropane-1-carboxylic acid (ACC), which increased the ROS production under both moderate and severe salt stress. However, NO levels decreased in the presence of ACC in cells exposed to 100 mM NaCl and did not change after treatment with 250 mM NaCl. The effect of ET on ROS production induced by salt stress could be blocked by silver thiosulphate (STS), an inhibitor of ET action. In accordance with the decreased ROS production STS reduced the death of cells in the presence of 250 mM NaCl. In the presence of ACC the enhanced ROS production concurrently with low NO levels led to the increased cell death after 100 mM NaCl treatment. These results show that the cell viability is determined by the ET generated ROS and NO ratio under salt stress

Impact of Economic and Financial Crisis on Human Resource Function in Four Eastern- European Countries in Light of an Empirical Research in 2009

When the crisis broke out in October 2008, the four countries (Bulgaria, Hungary, Romania and Slovakia) examined were in different situations, and, consequently, the governments of these countries reacted at different times. They did so, however, in very similar ways. Nevertheless, it is particularly important to know how their companies reacted to the crisis, and our study aims to find out what actions companies from these selected countries plan to take concerning the field of Human Resource Management (HRM) in the present financial and economic crisis. With a brief review of the literature, we demonstrate the role of HR in a period of depression, and then we present the findings of our empirical research, which was conducted from November 2008 to February 2009.Keywords: Human Resource Management, Crisis, Bulgaria, Hungary, Romania and Slovakia.

Differenciáldiagnosztikai és prognosztikai markerek alkalmazása korai arthritisekben, különös tekintettel a rheumatoid arthritisre = Application of differential diagnostic and prognostic markers in early arthritides especially in rheumatoid arthritis

Pályázatunkban differenciáldiagnosztikai és prognosztikai markerek alkalmazását tűztük ki célul korai arthritisekben, különös tekintettel a rheumatoid arthritisre (RA). Korszerű molekuláris biológiai módszerekel genetikai, virális és celluláris tényezőket vizsgáltunk. Eredményeinket számos nívós nemzetközi folyóiratban közültük, ezek közül az alábbiakat emeljük ki. Az RA specifikus szerológiai markere, az anti-ciklikus citrullinált peptid ellenanyag termelése összefüggést mutatott bizonyos HLA szubtípusokkal, főként a shared epitop tartalmú allélokkal.Elsőként vetettük fel az újonnan felfedezett TT vírus lehetséges patogenetikai szerepét systémás lupus erythematosusban (SLE) és súlyos polymyositisben. SLE B sejteken funkcionális abnormalitásokat találtunk az immunkomplexkötő receptorok működésében. Igazoltuk, hogy a spondylitis ankylopoeticában (SPA) és reaktív arthritisben a Toll-like receptorok szintjén észlelt funkcionális eltérések nem genetikailag determináltak. Paget-kórban új genetikai és klinikai összefüggéseket tártunk fel. Erdeményeink nemcsak a mozgásszervi betegségek patogenezisének megértéshez vihetnek közelebb, de klinikai konzekvenciái is lehetnek és új terápiás célpontok körvonalazadhatnak. | We aimed at studying differential diagnostic and prognostic markers in early arthritides, with special attention to rheumatoid arthritis (RA). Novel molecular biological methods were used to examine genetical, viral and cellular elements. Our main results were published in several international scientific journals. We showed that presence of the anti-cyclic citrullinated peptide antibodies, as the most specific serological markers of RA correlate with certain HLA DRB1 subtypes, mainly with the shared epitope. We first suggested the etiopathogenic role of the recently discovered TT virus in autoimmune rheumatic diseases such as systemic lupus erythematosus (SLE) and severe polymyositis. Moreover, SLE B cells were found to display functional abberations in the immune complex binding receptors. We verified that Toll-like receptor mediated functional alterations seen in ankylosing spondylitis and reactive arthritis are not determined genetically. Novel genetical and clinical correlations were found in Paget?s disease of bone. Our results may contribute to the better understanding of the etiopathogenesis of several rheumatic diseases but may also have clinical consequenses. Furthermore, novel pathways identified in our study might be targets for therapeutical interventions

Short-Term Salicylic Acid Treatment Affects Polyamine Metabolism Causing ROS–NO Imbalance in Tomato Roots

The phytohormone salicylic acid (SA) can influence the polyamine metabolism in plants. Additionally, polyamines (PAs) can regulate the synthesis of SA, providing an exciting interplay between them not only in plant growth and development but also in biotic or abiotic stress conditions. The effect of SA on polyamine metabolism of leaves is well-studied but the root responses are rarely investigated. In this study, tomato roots were used to investigate the effect of short-term exposition of SA in two different concentrations, a sublethal 0.1 mM and a lethal 1 mM. To explore the involvement of SA in regulating PAs in roots, the degradation of PAs was also determined. As both SA and PAs can induce reactive oxygen species (ROS) and nitric oxide (NO) production, the balance of ROS and NO was analyzed in root tips. The results showed that 0.1 mM SA induced the production of higher PAs, spermidine (Spd), and spermine (Spm), while 1 mM SA decreased the PA contents by activating degrading enzymes. Studying the ROS and NO levels in root tips, the ROS production was induced earlier than NO, consistent with all the investigated zones of roots. This study provides evidence for concentration-dependent rapid effects of SA treatments on polyamine metabolism causing an imbalance of ROS–NO in root tips

Fusaric acid-evoked oxidative stress affects plant defence system by inducing biochemical changes at subcellular level

Fusaric acid (FA) is one of the most harmful phytotoxins produced in various plant–pathogen interactions. Fusarium species produce FA as a secondary metabolite, which can infect many agronomic crops at all stages of development from seed to fruit, and FA production can further compromise plant survival because of its phytotoxic effects. FA exposure in plant species adversely affects plant growth, development and crop yield. FA exposure in plants leads to the generation of reactive oxygen species (ROS), which cause cellular damage and ultimately cell death. Therefore, FA-induced ROS accumulation in plants has been a topic of interest for many researchers to understand the plant–pathogen interactions and plant defence responses. In this study, we reviewed the FA-mediated oxidative stress and ROS-induced defence responses of antioxidants, as well as hormonal signalling in plants. The effects of FA phytotoxicity on lipid peroxidation, physiological changes and ultrastructural changes at cellular and subcellular levels were reported. Additionally, DNA damage, cell death and adverse effects on photosynthesis have been explained. Some possible approaches to overcome the harmful effects of FA in plants were also discussed. It is concluded that FA-induced ROS affect the enzymatic and non-enzymatic antioxidant system regulated by phytohormones. The effects of FA are also associated with other photosynthetic, ultrastructural and genotoxic modifications in plants