Magdolna Tóth

Role of slow delayed rectifier K+-current in QT prolongation in the alloxan-induced diabetic rabbit heart

Aim:  In diabetes mellitus, several cardiac electrophysiological parameters are known to be affected. In rodent experimental diabetes models, changes in these parameters were reported, but only limited relevant information is available in other species, having cardiac electrophysiological properties more resembling the human, including the rabbit. The present study was designed to analyse the effects of experimental type 1 diabetes on ventricular repolarization and the underlying transmembrane potassium currents in rabbit hearts.

Candidate genes of cuticle formation show characteristic expression in the fruit skin of apple

Based on the Arabidopsis model of production and transport of cuticular components in silico analysis of apple EST and genomic sequences identified candidate genes potentially involved in these processes. Expression profiling of the selected genes in apple leaves and fruit tissues at the stage of full tree ripeness showed them to be active in fruit skin, in some cases in a tissue-specific manner. Apart from sequence conservation, characteristic transcript profiles make these genes likely participants of fruit cuticle formation. Genes with putative functions in the fatty acid elongase complex, wax and cutin modifications, transport and a potential regulator were identified this way. Activity of some of the putative genes can be correlated with the known wax composition of the ‘Florina’ cultivar. Year-to-year and cultivar specific variations in expression of some of these genes indicate plasticity of lipid biosynthetic pathways in apple. Coordinated expression of several cuticle associated genes further supports their proposed role in cuticular lipid metabolism. The presented data suggest conservation of some key determinants of biosynthesis and transport of cuticular lipids between Arabidopsis epidermis and apple fruit skin.

Direct photothermal techniques for rapid quantification of total anthocyanin content in sour cherry cultivars

The analytical performance of the newly proposed laser-based photoacoustic spectroscopy (PAS) and of optothermal window (OW) method for quantification of total anthocyanin concentration (TAC) in five sour cherry varieties is compared to that of the spectrophotometry (SP). High performance liquid chromatography (HPLC) was used to identify and quantify specific anthocyanins. Both, PAS and OW are direct methods that unlike SP and HPLC obviate the need for the extraction of analyte. The outcome of the study leads to the conclusion that PAS and OW are both suitable for quick screening of TAC in sour cherries. The correlation between the two methods and SP is linear with R(2)=0.9887 for PAS and R(2)=0.9918 for OW, respectively. Both methods are capable of the rapid determination of TAC in sour cherries without a need for a laborious sample pretreatment.

S-genotyping of old apple cultivars from the Carpathian basin: methodological, breeding and evolutionary aspects

Apple exhibits self-incompatibility controlled by the multiallelic S-locus. Twenty-three old apple cultivars were S-genotyped using three different approaches (allele-specific polymerase chain reaction (PCR) + cleaved amplified polymorphic sequences (CAPS), consensus PCR + sequencing and consensus PCR + CAPS) to compare the robustness and reliability of these techniques and characterise genotypes from the Carpathian basin that might be useful in resistance breeding. Best results were obtained using the ASPF3 and ASPR3S consensus primer pair that detected 96% of all alleles carried by the 23 cultivars tested. Flow cytometry analysis was also needed to control the completeness of the genotypes as was seen in case of a tetraploid cultivar with only three assigned S-alleles. The genetic disparity between the old Carpathian basin and modern apple cultivars was indicated by differences in allele frequency data (S9, S24 and S26) as well as single nucleotide polymorphisms in S1, S2, S7S24 and S26 and indels in S20 and S26 alleles. An alignment of partial genomic sequences indicated trans-specific and trans-generic evolution of S-ribonuclease alleles in the Maloideae subfamily (S26 and S28) and a possibly recent introgression event (S1) between Malus × domestica and Malus sylvestris. These data suggest that the genome of old cultivars from the Carpathian basin was enriched by several Malus taxa and are free from the consequences of modern breeding. These cultivars may contribute to the widening of the genetic basis of cultivated apple and prevent genetic erosion in future commercial cultivars.

Potassium channels sensitive to combination of charybdotoxin and apamin regulate the tone of diabetic isolated canine coronary arteries.

Aims:  Functional roles of calcium‐activated potassium channels on the mechanical activity of epicardial coronary arteries obtained from a canine model of diabetes were investigated.

Effect of trans-resveratrol and ascorbigens on the fire blight pathogen Erwinia amylovora in the BioArena system

On the basis of our earlier observations, preliminary experiments were conducted with the fire blight pathogen Erwinia amylovora with the BioArena system using the potential antibacterial substances 1′-methylascorbigen (MeAG) as formaldehyde (HCHO) precursor and trans-resveratrol (RES) as HCHO mobilizer, capturer, and scavenger. Results showed characteristic, strong, dose-dependent antibacterial effects of both MeAG and RES present as chromatographic spots on the adsorbent layer. It is supposed that the weak antibacterial effect of AG may have originated from MeAG formed in situ on the layer by partial enzymatic methylation of AG. Addition of HCHO capture compounds (l-arginine, glutathione, glucosamine) to the culture medium before inoculation partially or totally reduced the antibacterial effect of both molecules, that is, this simplest aliphatic aldehyde, the endogenous HCHO molecule, participates in the antibacterial activity of these compounds. It follows from these results that there is a possibility of interaction between endogenous H2 O2 and HCHO in the chromatographic spots and it is supposed that these reactive molecules and potential derivatives, e.g. singlet oxygen (1O2) and ozone (O3), may be the causes of the destructive effect of the fire blight pathogen on fruit trees.