排序方式： 共有17条查询结果，搜索用时 15 毫秒
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Feeding deterrence and contact toxicity of Stemona alkaloids-a source of potent natural insecticides 总被引：1，自引：0，他引：1
Brem B Seger C Pacher T Hofer O Vajrodaya S Greger H 《Journal of agricultural and food chemistry》2002,50(22):6383-6388
On the basis of chronic feeding bioassays with neonate larvae of Spodoptera littoralis reared on an artificial diet, the methanolic leaf and root extracts from Stemona collinsae displayed very high insect toxicity compared to those of two Aglaia species, a commercial Pyrethrum extract, and azadirachtin, whereas S. tuberosa extracts demonstrated low activity in roots and no activity in leaves. Beyond that, in leaf disk choice tests against fifth instar larvae, S. collinsae showed strong antifeedant activity, whereas S. tuberosa was characterized by remarkable repellency. The anti-insect properties of both species were based on pyrrolo[1,2-a]azepine alkaloids, from which didehydrostemofoline (asparagamine A) was the major compound of the roots of S. collinsae, exhibiting the highest toxicity in feeding assays. Saturation and hydroxylation of the side chain in the co-occurring stemofoline and 2'-hydroxystemofoline, respectively, led to an increasing loss of activity. Contact toxicity tests with stemofoline and didehydrostemofoline exhibited even higher activities than those of Pyrethrum extract. Tuberostemonine was the dominating alkaloid in the roots of S. tuberosa, showing outstanding repellency but no toxic effects. 相似文献
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Serological detection of multiple retroviral infections in cattle: bovine leukemia virus, bovine syncytial virus and bovine visna virus 总被引：4，自引：0，他引：4
Individual experimental animals used in our studies on bovine leukemia virus (BLV) are routinely screened for the presence of antibodies to the three bovine lymphotropic retroviruses. We utilized these screening methods to examine frozen sera from eight herds for antibodies to BLV, bovine visna virus (BVV) and bovine syncytial virus (BSV). Serum samples from 235 animals in four dairy and four beef herds were analyzed. Detection methods used included indirect fluorescent antibody tests of virus-infected cell cultures (BLV, BSV, BVV) and agar gel immunodiffusion (BLV). Sera from the BLV-infected animals in the dairy herds showed the highest single (50%, 49/97) and multiple (30%, 29/97) infections compared with 5% (7/138) and less than 1% (1/138), respectively in the beef herds. Single BVV infections were not detected in the dairy herds, but 11% (11/97) of the sera contained antibodies to BVV plus BLV or BSV. Five sera from beef cattle had antibodies only to BVV and four were obtained from one herd. Only one beef serum of the 138 tested demonstrated multiple antibodies (BLV, BVV). 相似文献
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W. Meyer A. Schnapper G. Hülmann H. Seger 《Zeitschrift für Tierzüchtung und Züchtungsbiologie》2000,117(4):281-283
Based on a computer‐assisted method and regression analysis, several structural parameters of the hair cuticula pattern of primary hairs of 94 wild mammals and 44 breeds of 10 domesticated mammals were evaluated and compared between both groups. Biologically relevant relationships between the parameters examined could only be obtained for the wild animals. In this way domestication‐induced defects became evident for the hair cuticula pattern that is a typical structural feature of the hair shaft. 相似文献
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Serological study of the incidence and prevalence of antibodies to bovine leukemia virus in aged sera. 
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下载免费PDF全文 Ninety-seven sera collected from 21 animals that had been repeatedly sampled more than 17 years before and stored at -18 degrees C were tested for bovine leukemia virus antibodies using the agar gel immunodiffusion test. The prevalences for the different ages matched current prevalences in the same herd. The consistency of these results over a prolonged period suggests the validity of long-term retrospective seroepidemiological studies of this disease. Because the original titers could not be determined and some indications of a possible loss of activity, the results must be interpreted with a measure of caution. 相似文献
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Michelitsch A Rückert U Rittmannsberger A Seger C Strasser H Likussar W 《Journal of agricultural and food chemistry》2004,52(6):1423-1426
A simple and accurate differential pulse polarographic method has been developed for the determination of oosporein in the culture broth of the fungus Beauveria brongniartii. This hydroxybenzoquinone derivative is the only major secondary metabolite secreted by this entomopathogenic fungus, which is used as biological pest control agent (BCA) against Melolontha melolontha larvae. It can be found in the host organism as well as in the formulated product. The polarographic behavior of oosporein was examined in various buffer systems over the pH range 3-10. In Britton-Robinson buffer/methanol solution (3:7 v/v, pH 5.5) the differential pulse polarograms exhibited reproducible peaks at E(p) = -0.18 V vs silver/silver chloride/potassium chloride (3 M). Under these conditions, a plot of peak height vs concentration of oosporein was found to be linear over the range 5.9 x 10(-)(7) to 2.5 x 10(-)(5) M (0.18-7.74 microg mL(-)(1); r = 0.9998). The detection limit was calculated to be 54 ng mL(-)(1). To evaluate the concentration of oosporein, the standard addition method was applied. The analysis of oosporein in the culture broth led to a mean value of 524.9 microg mL(-)(1) broth with a relative standard deviation (S(rel)) of +/-2.6%. The proposed polarographic method is accurate, not time-consuming, and it is of low cost because no separation steps are necessary. 相似文献
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M J Graziano W Flory C L Seger C D Hebert 《American journal of veterinary research》1983,44(7):1238-1244
The effects of an orally administered Cassia occidentalis extract were studied in chickens. A 25 mM sodium bicarbonate solution effectively extracted the toxic principle. Toxic activity was reduced, but not eliminated, when the heated extract (90 C, 40 minutes) was administered. The toxic principle was in the pellet after centrifuging the extract at 38,000 X g. Daily administration of the extract produced weight loss and muscular weakness. Microscopic examination revealed skeletal and cardiac muscle degeneration and hepatocyte vacuolation. Electron microscopic examination revealed mitochondrial disruption. Respiratory studies on liver mitochondria isolated from treated chickens demonstrated lower phosphorylation ratios, lower respiratory control ratios, and lower rates of oxygen use. 相似文献
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L D Foil D D French P G Hoyt C J Issel D J Leprince J M McManus C L Seger 《American journal of veterinary research》1989,50(10):1771-1773
Bovine leukemia virus (BLV) was transmitted by horse flies, Tabanus fuscicostatus, from a cow with a lymphocyte count of 31,500/mm3 to goats and dairy calves. As few as 10 and 20 flies transmitted BLV to goats and calves respectively, but the minimal number of flies required to transmit the infection was not established. Groups of 150 and 100 T fuscicostatus transmitted BLV to beef calves from a cow with a lymphocyte count of 14,600/mm3. These results support a role for horse flies in the horizontal transmission of BLV. 相似文献