Mode of action of triadimefon in Ustilago avenae

Triadimefon [1-(4-chlorophenoxy)-3,3-dimethyl-(1,2,4-triazol-1-yl)-2-butanone], 1.5–2.0 μ/ml, inhibited the multiplication of sporidia of Ustilago avenae more strongly than it did the increase of dry weight. The treated sporidia appeared swollen, multicellular, and branched. At concentrations of 1.5–100 μg of triadimefon/ml, the oxidation of glucose was not affected. Increase in dry weight and synthesis of protein, RNA, and DNA were inhibited slightly, whereas cell division was acutely arrested. After an incubation period of 9.5 hr, microscopic studies revealed that daughter cells of the treated sporidia also contained one nucleus. In sporidia treated for 6 hr with triadimefon, both the total lipid content and its composition of fatty acids were not appreciably altered. The treated cells, however, differed from control cells by a higher content of free fatty acids. Triadimefon markedly interfered in sterol biosynthesis in Ustilago avenae. Gas chromatographic (glc) analysis and [¹⁴C]acetate incorporation studies indicated that ergosterol biosynthesis was almost completely inhibited by triadimefon; on the other hand, sterol compounds representing precursors of ergosterol (probably 4,4-dimethyl and C-4-methyl sterols) accumulated in treated sporidia. As the results indicate, the inhibition of conversion of immediate sterol precursors to ergosterol may be regarded as the primary target for the action of triadimefon in Ustilago avenae.     

Epidemiological characteristics of rabies in South Korea from 1993 to 2001

In the nine years from 1993 to 2001, 210 cases of rabies were recorded in domestic animals in South Korea; 115 cattle, 94 dogs and one farmed deer were affected. The annual incidence of rabies cases increased to a peak of 64 in 1998, and then decreased to about 30 cases per year. The cases were confined to the northern part of Kyounggi and Kangwon provinces. One hundred and forty-six cases (69.5 per cent) occurred in Kyounggi and 64 cases (30.5 per cent) in Kangwon province, and about 82 per cent of them were confined to two counties in Kyounggi province (29 per cent in Paju and 28.1 per cent in Younchun) and to Chulwon county in Kangwon province (25.2 per cent). However, over several years the outbreaks gradually moved south and east in both Kyounggi and Kangwon provinces. There were more rabies cases in cattle than in dogs, suggesting that the disease is transmitted by the sylvatic cycle. To investigate the relationship between rabies in domestic animals and wild animals, 107 wild animals, including Korean raccoon dogs, badgers, weasels and feral cats, were tested for rabies; 21 of the 67 Korean raccoon dogs tested (31 per cent) were infected. The cases in domestic animals were most common in winter, from December to February, and least common in summer, from June to September.     

Epitope identification and <Emphasis Type="Italic">in silico</Emphasis> prediction of the specificity of antibodies binding to the coat proteins of <Emphasis Type="Italic">Potato Virus Y</Emphasis> strains

A phage library containing 2.7 × 10⁹ randomly expressed peptides was used to determine the epitopes of three monoclonal antibodies that bind to the coat protein of potato virus Y. Construction of the consensus sequences for the peptides obtained after three selection rounds indicated that each antibody recognized a different epitope located within the first 50 N-terminal amino acids of the coat protein. The location of the epitopes was confirmed by heterologous expression of the N-terminal part of the coat protein in Escherichia coli, and, subsequently, by performing an immunological test with the three antibodies. The accuracy of the phage library was demonstrated by predicting in silico the cross-reactivity of the three antibodies with other potyvirus family members. ELISA and in silico predictions revealed the same results in almost every case. The potential of peptide phage libraries to optimize the use of antibodies in plant virology is discussed.