Phloem mobility of xenobiotics VI. A phloem-mobile pro-nematicide based on oxamyl exhibiting root-specific activation in transgenic tobacco     

Francis C. Hsu  Kingmo Sun  Daniel A. Kleier  Max J. Fielding 《Pest management science》1995,44(1):9-19

Phloem mobility is a desirable attribute for pesticides in many applications, and the physicochemical properties necessary for phloem mobility are now well understood. However, attempts to derivatize pesticides to make them phloem mobile are often frustrated by a concomitant loss of activity. This study describes a phloem-mobile pro-nematicide, a hydroxymethyloxamyl glucuronide (JR522) coupled with an in-situ activation mechanism in transgenic tobacco expressing Escherichia coli β-glucuronidase in its root tips. When applied foliarly to the transgenic tobacco, JR522 and its methyl ester (JM775) showed greater nematicidal activity than oxamyl against root-knot nematodes. This example of combining pro-pesticide chemistry with crop genetic engineering for site-specific activation provides a model system for demonstrating how to circumvent the often mutual exclusivity of phloem mobility and pesticidal activity. Additional advantages of this scheme include the potential mammalian safety of the propesticide, as exhibited by JR522 in this study, and a high degree of site-specific release of xenobiotics in plants.  相似文献   

Variability in the phloem restricted plant trypanosomes (Phytomonas spp) associated with wilts of cultivated crops     

Emmanuelle Muller  Daniel Gargani  Valérie Schaeffer  Jamie Stevens  Carmen Fernandez-Becerra  Manuel Sanchez-Moreno  Michel Dollet 《European journal of plant pathology / European Foundation for Plant Pathology》1994,100(6):425-434

Plant trypanosomatids (Phytomonas spp) have been isolated from the crude sap of coconut tress and oil palm trees affected with Hartrot or Marchitex diseases in South America andAlpinia purpurata affected with wilt in the Caribbean. They are also commonly isolated from the fruits and latex of Euphorbiaceae or Asclepiadaceae. Thirty-fourPhytomonas stocks were studied by isoenzyme electrophoresis (11 loci) in order to investigate genetic variability in the intraphloemic group. Our results showed that variability in phloem restrictedPhytomonas is very high, and that Marchitez or Hartrot associated trypanosomatids are not readily separated into two distinct groups. Moreover, the two isolates fromAlpinia are very close to the other intraphloemic isolates. The results confirm the existence of several distinct groups, comprising of at least 2 groups of phloem restricted trypanosomatids, not related to the host species, 3 groups of latex trypanosomatids, and one group of fruit trypanosomatids.  相似文献   

Satellite navigation. Europe's answer to GPS could be a boon for research     

Clery D 《Science (New York, N.Y.)》2005,310(5756):1893

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Skeleton of Euplectella sp.: structural hierarchy from the nanoscale to the macroscale     

Aizenberg J  Weaver JC  Thanawala MS  Sundar VC  Morse DE  Fratzl P 《Science (New York, N.Y.)》2005,309(5732):275-278

Structural materials in nature exhibit remarkable designs with building blocks, often hierarchically arranged from the nanometer to the macroscopic length scales. We report on the structural properties of biosilica observed in the hexactinellid sponge Euplectella sp. Consolidated, nanometer-scaled silica spheres are arranged in well-defined microscopic concentric rings glued together by organic matrix to form laminated spicules. The assembly of these spicules into bundles, effected by the laminated silica-based cement, results in the formation of a macroscopic cylindrical square-lattice cagelike structure reinforced by diagonal ridges. The ensuing design overcomes the brittleness of its constituent material, glass, and shows outstanding mechanical rigidity and stability. The mechanical benefits of each of seven identified hierarchical levels and their comparison with common mechanical engineering strategies are discussed.  相似文献   

Lymphotoxin-mediated regulation of gammadelta cell differentiation by alphabeta T cell progenitors     

Silva-Santos B  Pennington DJ  Hayday AC 《Science (New York, N.Y.)》2005,307(5711):925-928

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Platelet function and association of bovine viral diarrhea virus with platelets of persistently infected cattle     

Walz PH  Grooms DL  Bell TG  Kaiser L  Baker JC  Brock KV 《American journal of veterinary research》2005,66(10):1738-1742

OBJECTIVE: To determine whether viral involvement with platelets obtained from cattle persistently infected (PI) with bovine viral diarrhea virus (BVDV) is associated with altered platelet function or decreased platelet counts. SAMPLE POPULATION: Platelets obtained from 8 cattle PI with BVDV and 6 age-, sex-, and breed-matched uninfected control cattle. PROCEDURE: Manual platelet counts were determined, and platelet function was assessed through optical aggregometry by use of the aggregation agonists ADP and platelet-activating factor. Identification of BVDV in serum and preparations of purified platelets was determined by use of virus isolation tests. RESULTS: No significant difference in platelet counts was detected between cattle PI with BVDV and control cattle. In response to the aggregation agonists, maximum aggregation percentage and slope of the aggregation curve were not significantly different between cattle PI with BVDV and control cattle. We isolated BVDV from serum of all PI cattle and from purified platelets of 6 of 8 PI cattle, but BVDV was not isolated from serum or platelets of control cattle. CONCLUSIONS AND CLINICAL RELEVANCE: Isolation of BVDV from platelets in the peripheral circulation of cattle immunotolerant to BVDV does not result in altered platelet function or decreases in platelet counts.  相似文献   

Prevalence, outcome, and health consequences associated with persistent infection with bovine viral diarrhea virus in feedlot cattle   总被引：1，自引：0，他引：1  

Loneragan GH  Thomson DU  Montgomery DL  Mason GL  Larson RL 《Journal of the American Veterinary Medical Association》2005,226(4):595-601

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Correlation between hepatobiliary scintigraphy and surgery or postmortem examination findings in dogs and cats with extrahepatic biliary obstruction, partial obstruction, or patency of the biliary system: 18 cases (1995-2004)     

Head LL  Daniel GB 《Journal of the American Veterinary Medical Association》2005,227(10):1618-1624

OBJECTIVE: To evaluate the usefulness of serum biochemical variables and scintigraphic study results for differentiating between dogs and cats with complete extrahepatic biliary obstruction (EHO) and those with partial EHO or patent bile ducts. STUDY DESIGN: Retrospective case series. ANIMALS: 17 dogs and 1 cat. PROCEDURE: Animals that underwent hepatobiliary scintigraphy and had either surgical or postmortem confirmation of the degree of bile duct patency were included. Scintigraphic images were evaluated and biliary tracts were classified as patent, partially obstructed but patent, or obstructed. Surgery or postmortem examination was considered the gold standard for diagnosis, and compared with those findings, sensitivity and specificity of scintigraphy were calculated. RESULTS: With absence of radioactivity in the intestinal tract as the diagnostic criterion for EHO, the sensitivity and specificity of scintigraphic diagnosis were both 83% when final images were acquired at 19 to 24 hours, compared with 100% and 33%, respectively, when 180 minutes was used as the cutoff time. Animals with partial biliary obstruction had less intestinal radioactivity that arrived later than that observed in animals with patent biliary tracts. CONCLUSIONS AND CLINICAL RELEVANCE: Animals in which intestinal radioactivity has not been observed after the standard 3 to 4 hours should undergo additional scintigraphic imaging. Findings in animals with partial biliary obstruction include delayed arrival of radioactivity and less radioactivity in the intestine. Distinguishing between complete and partial biliary tract obstruction is important because animals with partial obstruction may respond favorably to medical management and should not be given an erroneous diagnosis of complete obstruction.  相似文献   

Prevalence of Ehrlichia canis infection in thrombocytopenic dogs from Rio de Janeiro, Brazil     

Macieira Dde B  Messick JB  Cerqueira Ade M  Freire IM  Linhares GF  Almeida NK  Almosny NR 《Veterinary clinical pathology / American Society for Veterinary Clinical Pathology》2005,34(1):44-48

BACKGROUND: Infection with Ehrlichia canis causes a highly variable, multisystemic disease in dogs. Nevertheless, many clinicians in Rio de Janeiro, Brazil, use the presence of only thrombocytopenia to make a presumptive diagnosis of E canis infection. OBJECTIVE: The objective of this study was to determine the prevalence of E canis in thrombocytopenic dogs from Rio de Janeiro, Brazil, using polymerase chain reaction (PCR). METHODS: Following DNA extraction of whole blood samples from 226 dogs, PCR assays were done using primers for rickettsial DNA (including Ehrlichia spp, Anaplasma platys and A phagocytophilum) and using E canis-specific primers (16S rRNA gene). Dogs were grouped as thrombocytopenic and nonthrombocytopenic based on platelet counts. The null hypothesis that there was no difference in the prevalence of E canis in these groups was rejected at P<.05. RESULTS: Thirty-six (32.1%) of the thrombocytopenic dogs and 4 (3.5%) of the nonthrombocytopenic dogs were positive for rickettsial gene sequences (P<.0001). Further, 30 (26.8%) of thrombocytopenic dogs and 4 (3.5%) nonthrombocytopenic dogs were positive for E canis-specific gene sequences (P<.0001). CONCLUSIONS: Although the prevalence of E canis infection was higher in thrombocytopenic dogs, less than one third of these dogs had demonstrable E canis infection. Thus, thrombocytopenia is not specific for the detection of E canis infection and should not be used solely to establish a diagnosis of canine ehrlichiosis, even in a geographic area with relatively high disease prevalence.  相似文献   

Azadirachtin-impregnated traps for the control of Dermanyssus gallinae   总被引：2，自引：0，他引：2  

Lundh J  Wiktelius D  Chirico J 《Veterinary parasitology》2005,130(3-4):337-342

The effect of neem oil (azadirachtin), originating from the tree Azadirachta indica, was investigated as a potential compound to control the poultry red mite, Dermanyssus gallinae. In vitro tests were performed to determine the most appropriate formulation of neem extracts and concentration of the substance to be used. Cardboard traps containing 20% neem oil were placed at the mites’ aggregation sites, out of reach of the hens, in a floor system for layers containing approximately 2400 birds. Treated traps were replaced every week for 4 weeks. Throughout the study, the parasite population was monitored by collections of mites with untreated plastic traps. A 92% reduction of D. gallinae was recorded.  相似文献