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11.
T Takahashi Y Tamura T Sawada S Suzuki M Muramatsu T Fujisawa Y Benno T Mitsuoka 《Research in veterinary science》1989,47(2):275-276
The enzymatic activities of 39 strains of Erysipelothrix rhusiopathiae and 34 of E tonsillae were determined with the API ZYM system. The profiles of these two species were very similar, differing solely in N-acetyl-beta-glucosaminidase activity. Whereas 90 per cent of strains of E rhusiopathiae exhibited strong activity with N-acetyl-beta-glucosaminidase, positive reactions were observed for this enzyme in only 24 per cent of strains of E tonsillae. These results support previous DNA-DNA hybridisation studies and suggest that E tonsillae is a new species of the genus Erysipelothrix. 相似文献
12.
The protective effect of porcine antiserum prepared against culture filtrate (CF) of an attenuated strain of Erysipelothrix rhusiopathiae (serovar 2) in mice to challenge with 20 virulent strains of 18 serovars and one type N was investigated. Passively immunized mice survived after challenge with serovars 1a, 1b, 2, 5, 6, 8 (strain Goda), 11, 12, 15, 16, 21 or type N, but 10-30% mortality occurred in immunized mice challenged with each strain of serovars 4, 7, 8 (strain 911), 9, 18 or 19 and 70% mortality to serovar 10 (strain 2179). All immunized mice died after challenge with serovar 20 (strain 2553). Non-treated control mice died after challenge with all serovars and the type tested. 相似文献
13.
Adherence of four virulent and four avirulent strains of Erysipelothrix rhusiopathiae, serovar 1a, to porcine kidney cell lines, PK-15 and ESK cells, was examined in an in vitro system. The virulent strains adhered well to the cells (range of means, 9.95 +/- 0.87-36.01 +/- 1.10 per cell). In contrast, the avirulent strains showed negligible adherence to the cells (range of means, 0.11 +/- 0.04-1.41 +/- 0.13 per cell). Pretreatment of bacteria with heat, trypsin, or antiserum resulted in a marked decrease in adherence. Scanning electron microscopic examination revealed that the bacteria attached directly to the microvilli of cells. 相似文献
14.
Huimin Yang Murray Unkovich Ann McNeill Xianzhi Wang 《Biology and Fertility of Soils》2011,47(4):377-385
Symbiotic N2 fixation by lucerne (Medicago sativa) has capacity to provide significant inputs of N to agro-ecosystems, and the species has also been shown to scavenge soil
mineral N and thus act as a sink for excess reactive N. The balance between these two N cycle processes was investigated in
an extensive irrigated lucerne growing region where nitrate contamination of groundwater has been reported. We sampled 18
permanent pure lucerne stands under irrigation for standing dry matter, total shoot N, and N2 fixation using 15N natural abundance along with activity of the inducible enzyme nitrate reductase as indicators of use of soil NO3− by lucerne. On average 65% of lucerne N was obtained from symbiotic N2 fixation. Converting standing dry matter estimates to annual N2 fixation amounts we calculated average N2 fixation of 311 kg N/ha, including N in roots and nodules. Uptake of N from soil by lucerne was calculated to be 181 kg N/ha/year.
We were not able to identify the source of this soil mineral N, although nitrate reductase activity of lucerne was higher
than that of non-N2 fixing species examined. 相似文献
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The effects of ammonia and nitrite on vigour, survival rate, moulting rate of zoea of blue swimming crab, Portunus pelagicus, were studied. A total of five nitrite-N treatments (26.67, 53.34, 106.68, 213.36, 426.72 mg/l) and a control (no nitrite-N added) were
set up for the acute nitrite-N toxicity experiment; a total of five ammonia-N treatments (8.43, 16.86, 33.72, 67.44, 134.88 mg/l)
and a control (no ammonia-N added) were set up for the acute ammonia-N toxicity experiment. The results showed that the vigour,
survival rate and moulting rate of zoea of the blue swimming crabs exposed to over 53.34 mg/l were significantly different
(P < 0.05) from the control group. The zoea LC50 values (mg/l) of nitrite-N were 179.47, 76.56, 66.70, 37.49, 25.01, 25.35, 25.34 mg/l for 24, 36, 48, 60, 72, 84, 96 h, respectively.
The vigour, survival rate and moulting rate of zoea of the blue swimming crabs exposed to over 16.86 mg/l were significantly
different (P < 0.05) from the control group. The zoea LC50 values (mg/l) of ammonia-N were 51.04, 39.62, 38.72, 24.43, 16.90, 13.42, 11.16 mg/l for 24, 36, 48, 60, 72, 84, 96 h, respectively.
The zoeae are highly sensitive to ammonia and nitrite, and the toxicity of ammonia and nitrite on Portunus pelagicus decrease with development of this crab. 相似文献