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Yaxin Li Matthew R. Gronquist Guixia Hao Michele R. Holden Anatol Eberhard Russell A. Scott Michael A. Savka Erno Szegedi Sandor Sule Thomas J. Burr 《Physiological and Molecular Plant Pathology》2005,67(6):101
Agrobacterium vitis causes crown gall disease on grapevines. It also induces a specific necrosis on grape roots and a hypersensitive response (HR) on tobacco that are regulated by a complex quorum-sensing regulatory system. Strain F2/5 produces at least six N-acyl-homoserine lactones (AHLs) that function as signal molecules in quorum-sensing. The AHLs differ in acyl side chain length (8–16 carbons) as determined by gas chromatography/mass spectrometry and electrospray ionization tandem mass spectrometry. Mutant derivatives of F2/5 differ in ability to cause necrosis and the HR and show variable AHL profiles as determined by a thin-layer chromatography/biosensor assay. All wildtype A. vitis strains revealed the presence of long-chain AHLs regardless of tumorigenicity or ability to cause the HR. Whereas genes encoding long-chain AHLs are predicted to reside on the F2/5 chromosome, the determinants for short-chain AHLs were shown to be located on conjugal plasmids. 相似文献
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Absorption of inorganic, trivalent and hexavalent chromium following oral and intrajejunal doses in rats 总被引：1，自引：0，他引：1
The intestinal absorption of trivalent and hexavalent chromium (Cr) given orally (experiment I) or infused in the intestine (experiment II) was investigated in rats. The nonabsorbable form of chromium (51Cr2O3) and water-soluble and more absorbable Na2(51)CrO4 (the hexavalent form of Cr) were compared. Total retention of chromium given orally ranged around 15 percent of the dose, regardless of the chromium compounds applied. The absorption rate of chromic oxide, which is considered a nonabsorbable compound, was 14.4 as a percentage of chromium intake. This result indicates that some loss of chromium has to be taken into account in metabolic trials made by the indicator method. In isolated rat intestine, from the injected Cr 2.5% of chromic oxide and 43.2% of sodium chromate were absorbed during an hour (experiment II). The absorbed chromium was transferred to the liver where the liver tissue retained 10.9% of chromic oxide and 51.1% of sodium chromate. Radioactivity of v. cava caudalis following intestinal injection of Na2CrO4 was thirtyfold greater than after Cr2O3 dosing. This phenomenon can be explained by the lower blood clearance of chromate. Different absorption rate of chromate depending on the route of administration could be due to the fact that the hexavalent form given orally was reduced to Cr3+ in the acidic environment of the stomach. When Na2CrO4 was infused directly in the intestine of rats, such reduction could not occur. This means that the acidic gastric juice might play a role in inhibiting the intestinal absorption of Na2CrO4 when this compound is given orally. 相似文献
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H Erno 《Acta veterinaria Scandinavica》1971,12(3):451-453
According to several authors specific antibodies can be demonstrated in serum of cows with mycoplasma mastitis. For practical reasons, and for pathogenetic studies, it would be of interest if presence of antibody in milk could be established. To elucidate this and to examine the pathogenicity of the type strain, PG 11, of M. bovigenitalium, the experiment described below was conducted. 相似文献
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Mycoplasmosis: experimental and spontaneous infections of the genital tract of bulls 总被引：2，自引：0，他引：2
A strain of M. bovigenitalium was isolated from semen of a bull (K) with chronic seminal vesiculitis. Using this strain a vesiculitis of the same type as found in bull K, characterized by simultaneous acute and chronic lesions, was induced experimentally in 2 bulls by direct inoculation into the vesicular glands. In the acute phase a marked infiltration of eosinophils was found in the interstitial tissues and alveoli whereas in the chronic phase fibrosis, lymphoid and epithelial hyperplasia were seen. Degeneration of vascular walls and connective tissue was common.On inoculation into the testis of 3 bulls a chronic epididymitis and ampullitis were produced. The histological changes were of the same type as found in the vesicular glands of the 3 bulls with vesiculitis.By indirect hemagglutination a specific and significant increase in serum antibody could be demonstrated. As the titers were low and the maximum titers were reached early, it will probably not often be possible to make an etiological diagnosis on the basis of serological evidence.A comparative experiment employing the type strain (PG 11) of M. bovigenitalium was performed. A rise in antibody titer was seen, but neither clinical nor histological changes could be demonstrated. 相似文献
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Mycoplasmosis: infections of the genital organs of bulls 总被引：3，自引：0，他引：3
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Bovine mycoplasmas: cultural and biochemical studies. II 总被引：4，自引：0，他引：4
A number of biochemical and biological tests have been performed using reference strains of presently known mycoplasma species or sero-groups of bovine origin. The purpose of these investigations was partly to fulfil the requirements of “The Subcommittee on the Taxonomy of Mycoplasmatares” in describing new species of mycoplasmas, and partly to select methods which might be of value in daily diagnostic work. Concerning the latter point, the following tests are recommended for strains belonging to the digitonin resistant genus Acholeplasma: catabolism of galactose, xylose, aesculin and arbutin. In the genus Mycoplasma, which is digitonin sensitive, 5 tests are of special value: catabolism of glucose and arginine, phosphatase activity, formation of “film and spots”, and serum digestion. 相似文献
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H Erno 《Acta veterinaria Scandinavica》1977,18(2):176-186
It would be an advantage, under many circumstances, to be able to make use of polyvalent antisera in the process of identifying mycoplasmas. As the indirect immunofluorescence test is sufficiently sensitive and also generally accepted as being rather specific, this technique was chosen to investigate whether polyvalent antisera are applicable in routine identification of mycoplasmas. Three polyvalent sera were used, each consisting of 9 or 10 rabbit antisera raised against 29 of the more common species of the genus Mycoplasma. Twenty-six field strains were examined. One strain did not react with any of the 3 polyvalent antisera although it was later identified as M. bovigenitalium. The remaining 25 strains reacted with 1 and only 1 of the polyvalent antisera and were subsequently identified by immunofluorescence utilizing monospecific antisera. Strains of the following species were identified: M. arginini, M. bovigenitalium, M. bovis, M. bovoculi, M. canis, M. capricolum, M. cynos, M. edwardii, M. hominis, M. hyorhinis, M. molare, M. mycoides subsp. mycoides and M. opalescens. It is concluded that polyvalent antisera may be used in identification procedures and thereby permit the use of a limited number of monospecific antisera without preceding biochemical testing. 相似文献