Virus symptoms were observed on Hedge bindweed (Calystegia sepium) a well known plant in Hungary. In the literature there is no record of virus infection on Hedge bindweed, therefore, investigations were carried out to determine the causal agent. Sap from leaves showing virus-like symptoms was inoculated onto test plants inducing systemic infection on Nicotiana clevelandii, N. benthamiana, local lesions on Chenopodium quinoa and no infection on Datura stramonium and Cucumis sativus. Sap of N. clevelandii was examined by electron microscopy, showed the presence of long flexous particles. The biological and other properties of the virus have also been studied. Properties of particles in sap were as follows: TIP (thermal inactivation point): 78 °C, LIV (longevity in vitro): 26 days and DEP (dilution end point): log 10 minus 5. The size of coat protein is 36 kDa, and the genome consists of 7-8000 nt RNA. Double-stranded cDNA were produced using random hexanucleotide primers, cloned and sequenced. BLAST search of sequence databases revealed nucleotide sequence identity with carlaviruses. Further investigations are needed to decide whether the virus isolated from Hedge bindweed is a new carlavirus or a new strain of an existing carlavirus.
The most obvious symptom of systemic virus infection is the mosaic pattern of the leaves. Yellowing, chlorosis is also frequent and characteristic sign of the altered photosynthetic activity. Virus infection effects photosynthesis in a complex manner, depending on the particular host-virus combination. The symptoms are basically different in the incompatible or the compatible host-virus interaction.
Authors:A. Almási, I. Tóbiás, I. Manoussopoulos, Zs. Basky and L. Palkovics
Nucleotide and amino acid sequences of the helper component protease (HC-Pro) and the coat protein (CP) of two Hungarian
Potato virus Y
(PVY) isolates, differing in aphid transmissibility were determined. Isolate PVY-5 belongs to the common “O” strain (PVY
), whereas isolates PVY-98 and PVY-111 belong to the “N” (PVY
) and the PVY-NTN and PVY-H to the “NTN” (PVY
) strains, respectively. The PVY-5 isolate varied significantly from the others in aphid transmission and in the ability to systemically infect potato plants. To elucidate whether these differences were due to mutations affecting known functional motifs, the corresponding cistrons of the two proteins were sequenced and aligned. Our analysis showed that none of the well-known motifs, responsible for aphid transmission in the two proteins had been affected. However, the defective isolate had two natural mutations in the HC-Pro in the vicinity of the PTK motif, and a number of mutations in the CP, distributed both in the N-terminus and the central region. As these two proteins are the only known viral participants in the aphid transmission mechanism, it is likely that some of the observed mutations might be involved in this process. Thus, our results indicate that other, previously unidentified sequences or factors may influence virus-vector interactions and transmission of PVY.
Authors:S. Bojcsev, A. Almási, H. Simon, P. Perjési and Emil Fischer
In the extrahepatic drug metabolism the intestinal tract can play an important role. These experiments were designed to study the biotransformation of p-nitrophenol (PNP) in the small intestine in the rat. Various segments of the small intestine (proximal and distal jejunum, terminal ileum) were perfused with isotonic solution in vivo containing different concentrations of PNP (20–100–500–1000 μM) and the concentrations of metabolites (PNP-G: p-nitrophenol glucuronide, PNP-S: p-nitrophenol sulfate) were determined in the perfusion medium. It was found a decreasing tendency in the glucuronidation from the proximal to distal segment of the small intestine: e.g. 430 nmol, 240 nmol, and 100 nmol PNP-G appeared in the perfusion medium in the proximal, distal jejunum and in the terminal ileum, respectively, when 500 μM PNP was luminally perfused for 90 minutes. Similar ratio was found at the luminal perfusion of other PNP-concentrations, too. Luminal appearance of sulfoconjugate of PNP was considerably lower and no clear gradient tendency in the formation of PNP-S could be detected in the small intestine from the proximal to distal segment. Our results show that there are considerable differences in drug metabolism in various segments of the small intestine. We have found a gradient conjugating activity from proximal to distal segment of small intestine in the glucuronidation of PNP.
Authors:G. Jenser, Aszteria Almási, Gabriella Kazinczi, A. Takács, Ágnes Szénási and R. Gáborjányi
Ecological background of the dissimilar ways of the spread of
tomato spotted wilt virus
(TSWV) was investigated in the fields in tobacco stands and in the greenhouses in forced green pepper and tomato cultures, under continental climatic conditions in Hungary.
Authors:A. Almási, Sz. Bojcsev, T. Fischer, H. Simon, P. Perjési and Emil Fischer
The aim of these experiments was the investigation of the correlation between the metabolic enzyme activities and the intestinal and hepatic excretion of p-nitrophenol (PNP) and its metabolites (PNP-glucuronide: PNP-G and PNP-sulfate: PNP-S) in the same group of rats (n = 10). A jejunal loop was perfused with isotonic medium containing PNP in a concentration of 500 μM. The samples were obtained from the luminal perfusion medium and from the bile. For enzyme assays tissue samples were obtained from the liver and jejunum at the end of experiments. Significant differences were calculated by the Student’s t-test. The activity of UDP-glucuronyltransferase and sulfotransferase was about three times higher in the liver than in the small intestine. The activity of the ß-glucuronidase was about six times higher, the activity of the arylsulfatase was approximately seven times greater in the liver than in the jejunum. No significant difference was found between the luminal appearance and the biliary excretion of PNP-G. Contrary to these findings, the biliary excretion of PNP-S was significantly higher than the luminal appearance of PNP-sulfate. It can be concluded that no direct correlation exists between the activity of metabolic enzymes and the excretion rate of PNP-metabolites in the liver and in the jejunal segment of the small intestine.