Krómvegyületek és vírusfehérjék által okozott stresszfolyamatok vizsgálata Schizosaccharomyces pombe sejteken

Abstract

The homeostasis reveals the dinamic balance, allows to the living systems the self-supporting operations and also to be able to buffer the impacts ofexternal changes as well. Attacts come not only from the extralell world but in the intracellular space happen because of the outcome of respiratory processes orsome by-products of enzymatic reactions and so for example reactive oxigene species (ROS) are able to act as harmful agents to the cells.Some elements including special metal compounds are essential for living organisms to exist. In healthy environment metals usually represented as traceelements, enzymatic contents in nanomolar concentration. Widely used in industry there are some special toxic compounds containing the unstabile, reactiveCrVI. The reduction of this chromium ion happens rapidly, generating reactive intermediers which are capable to induce wounding intracellular reactions such asinhibition of DNA repair enzymes or suppression of signal transduction pathways. Certain stress from the extracellular world so can be responsible forgenotixicity and malignus transformation. Nevertheless there are well-characterized microorganisms resistant to the harmful effects of heavy metals (Nies 1999).Most of the genetic background mechanisms impacked by the oxidative stress from different sources still remains unknown. The idea of creating andinvestigating mutant strains was to characterize chromate-sensitivity and –tolerance in fission yeast. To learn more about mutant genes and gene products can beuseful to determine which genes are affected and how are they involved in the mechanisms induced by oxidative stressors, heavy metals for example chromiumin living cells (Halliwell and Gutteridge, 1999).Viral proteins are mostly responsoble for the effective infection and also act as stress factors for the organisms attacked by the virus. The HIV-1 virus(human immunodeficiency virus type 1) infection often leads to AIDS (acquired immune deficiency syndrome) encodes some of accessory proteins whichpossibly play some kind of role in viral infection. This virus also bears a 15 kDa virion associated protein Vpr (viral protein type R) (Elder et al., 2002).Vpr protein has been shown to be responsible for the effectiveness of the viral infection, helps viral replication cycle and acting on several cell contentsenhances viral pahtogenesis. Some of the earlier reports say the Vpr is able to cause oxidative stress in host cells, but no data has been shown about theconnetcion between Vpr and oxidative stress or Vpr-expressing S. pombe cltures. Some stages of viral infection commonly generate oxidative stress in host cellsthat is why the therapy ot the AIDS patients contains antioxidant therapy commonly known as coctail (Dunable 1998). The question is whether the intracellularstress caused by the Vpr expression and the oxidative stress from the extracellular world are really adds.The barley yellow dwarf (BYD) virus, a global desease of cereals appears with the primary symptoms of the infection such as retarded growth andyellish color of the plants. This has an enormous economical impact on crop production because of the significant yield loss. The role of the movement protein(MP) during the BYDV desease has not been reported yet. The only way to identify MP as a potential viral pathogenic determinant to study the effects of BYDviral proteins on basic cellular functions especially on plant growth. If MP has impact on cell proliferation or MP inhibits cell division reveals a possibleexplanation of dwarf plants. Due to inherent technical difficulties in studying the effects of viral proteins in plant cells in vivo, a S. pombe model system was usedto carry out initial functional screening of special gene products and further validate those findings in plant cells. Use of fission yeast as a model organismstudying gene activities of high eukaryotes including viral gene functios have been demostrated previously several times, thus making this unicellular organisman efficient genetically tractable system to study plant-related genes.