A cytopathic agent was isolated using Vero cells from the culture medium of HeLa cells that had been used for more than 30 years in our laboratory. This agent, termed U-1 strain, was serially passed in Vero cells with distinct CPE. Particles of U-1 strain negatively stained with phosphotungstic acid exhibited a distinct surface that resembled Aichi virus. The RNA genome of U-1 strain comprises 8374 nt, with a genome organization analogous to that of picornaviruses. Possible cleavage sites of the large ORF, which encoded a leader protein prior to the capsid protein region, were assigned following amino acid alignment with Aichi virus. The virus sequence had 33 and 75 % amino acid identity with the Aichi virus VP1 and 3D regions, respectively, but no more than 23 and 36 % with those of the prototype strains of other Picornaviridae. The dendrogram based on the P1, P2 and P3 proteins indicated that U-1 strain is genetically included in the genus Kobuvirus but is distinct from Aichi virus. Of 72 cattle sera, 43 (59?7 %) were positive for neutralizing antibody against U-1 strain at a titre of 1 : 8 or more. However, sera from 190 humans, 242 monkeys, 139 pigs, 5 horses, 22 dogs and 9 cats did not neutralize U-1 strain at a 1 : 4 dilution. RNA corresponding to U-1 strain was detected in 12 (16?7 %) of 72 faecal samples from cattle by RT-PCR. These results indicated that U-1 strain, suspected to be a contaminant from calf sera, is a new species of the genus Kobuvirus, now termed bovine kobuvirus.
We evaluated a multiresidue method for determination of pesticides in agricultural products by SCAN mode GC/MS coupled with three kinds of database for 253 pesticides: relative retention time, mass spectra and calibration curve (SCAN method). Twenty-six pesticides, a total of 131 pesticides were detected in samples by the SCAN method. The detection results agreed closely with those of the SIM mode GC/MS method using calibration standards (SIM method). The ratios of the SCAN method to the SIM method ranged from 0.3 to 3.1 with SD values of 0.63. It was judged that the SCAN method could be applied to the screening analysis of pesticide residues in agricultural products, provided that the sample preparation method makes it possible to e#ective-ly remove sample matrixes with minimal loss of analytes.
A sensitive and quantitative multiresidue method using NCI mode GC/MS and GC-micro ECD for determining pesticides in animal and fishery products was established. The crude sample extract obtained by acetoneῌhexane extraction for solid samples or acetonitrile extraction for liquid samples was cleaned up with a GPC/SPE system. The first GPC pesticide fraction containing lipids and pigments was selectively collected, and loaded directly onto a graphitized carbon/PSA 2-layered column. After the second GPC pesticide fraction was collected, the 2-layered column was eluted with acetoneῌhexane (3 : 7). The combined eluate was subjected to NCI-SIM/Scan mode GC/MS for semi-quantification. After fractionation by Florisil cartridge column SPE, each fraction was subjected to dual-column GC-micro ECD for quantification. Average recoveries (n̮5) of pesticides, except for chlorothalonil and some others, from fortified samples ranged from 76.8̮ to 107.9̮ with RSD values of ̮9.7̮.
(Received May 26, 2008)Key words: Q̲̰Ὸ pesticide residue; ῖQQ΅ animal and fishery product; ῴQῢ̱ ̲Ό̱ ̲ῼῲῐ gel permeation chromatography (GPC); QῐῘQ solid-phase extraction (SPE); ῬQ Qῳ̱ Q negative chemical ionization (NCI); ̱ῶ̱ ̲Ό̱̲ῼῲῐ gas chromatography (GC); Q̲`Q̱ mass spectrometry (MS); ̲ῳ̱ ̯Q̱QQQQQ micro-electron capture detector (micro ECD)
Based on the data for pesticide residues in vegetables and fruits collected in Aichi prefecture (fiscal years 2001ῌ2005), we selected groups of foods and pesticides that would allow e$cient and e#ective inspection under the positive list system. Statistical analyses were done to examine the rates of detection of pesticides and the numbers of kinds of pesticides detected in samples of domestic vegetables, domestic fruits, imported vegetables, and imported fruits. The rate of detection of pesticides has decreased gradually in domestic vegetables. The number of di#erent kinds of pesticides detected in each sample was significant higher in domestic fruits. Data for previous years were reassessed in terms of the present maximum residue limits (MRL), and classified as relative value to the MRL. The proportion of pesticides detected at levels that exceeded the MRLs showed a decreasing tendency. In addition, we were able to identify combinations of pesticides and agricultural commodities in which the MRLs were more likely to be exceeded.
(Received January 18, 2008)Key words: ̰ῷQ῾ pesticide residue; ῼ̱ῴ΅Ὼ̲̱ῶQ̯ positive list system; ῶQ vegetable; ̳Q fruit; `̱̲´ῶ̲Ό΅ῐ gas chromatography (GC); ̯Q̳Q statistical analysis
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