Ján Košuth

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Level of expression of the hyp-1 gene encoding for the phenolic coupling protein which is assumed to be involved in conversion of emodin to hypericin in vitro was compared in different organs of Hypericum perforatum seedlings in early stage of development in order to find out the sites of hypericin biosynthesis. Hypericins are accumulated in multicellular(More)
Extreme low temperatures cause plants multiple stresses, among which oxidative stress is presumed to be the major component affecting the resultant recovery rate. Plants of Hypericum perforatum L., which are known especially for the photodynamic activities of hypericins capable of producing reactive oxygen species under exposure to visible light, were(More)
Hairy root-regenerated clones of Hypericum perforatum L. grown in vitro similarly to those successfully adapted to ex vitro conditions showed phenotype features typical for plants transformed with Agrobacterium rhizogenes T-DNA. These included reduced apical dominance, increased branching, dwarfing and reduced fertility. Transgenic clones differed in(More)
The extent of phenotypic variation of St. John's wort (Hypericum perforatum L.) plants transformed with wild agropine ATCC 15834 Agrobacterium rhizogenes plasmid was evaluated with respect to the number of rol genes integrations. The transfer of T(L)-DNA to plant explants during each transformation event was incomplete with different rolA, rolB, and rolC(More)
The content of hypericins in in vitro regenerated Hypericum perforatum plants (R 0) and four generations of their seed progeny (R 1–R 4) was compared. The mean content of hypericins in field-grown plants over the period 1992–2002 gradually increased under selection, and in the R 4 generation it was almost seven-times higher than that in the R 0 somaclones.(More)
Labelling of DNA in replicating cells using 5-bromo-2´-deoxyuridine (BrdU) is widely used, however the rapid clearance and metabolisation of BrdU in the living organism is a critical issue. Although the pharmacokinetic of BrdU in experimental animals is empirically approximated, the exact time-curve remains unknown. Here we present novel method for(More)
Hypericum perforatum L. in vitro cultured shoot tips were characterised at the physiological, biochemical and molecular levels following recovery from cryogenic treatment using the plant vitrification solutions PVS2 and PVS3. This comparative study revealed an increase in recovery and regrowth of explants cryoprotected with PVS3. Among the physiological(More)
The spatial and temporal expression of dbat and dbtnbt genes involved in the later steps of paclitaxel biosynthesis in relation to baccatin III and paclitaxel accumulation in Taxus baccata L. germinating embryos and seedlings was investigated. The steady-state of mRNA transcripts was measured by quantitative real time polymerase chain reaction (qRT-PCR),(More)
Limited native resources of paclitaxel from Taxus trees initiated the research to produce this compound by biotechnology. In vitro plant cell culture systems have been used for large-scale production of paclitaxel and related taxanes. In the past decade, several genes involved in the taxane biosynthetic pathway have already been sequenced and cloned. This(More)
Isoprenyl diphosphate synthases (IDSs) catalyze some of the most basic steps in terpene biosynthesis by producing the prenyl diphosphate precursors of each of the various terpenoid classes. Most plants investigated have distinct enzymes that produce the short-chain all-trans (E) prenyl diphosphates geranyl diphosphate (GDP, C10 ), farnesyl diphosphate (FDP,(More)