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Irregular plagues of house mice, Mus musculus, incur major economic impacts on agricultural production in Australia. The efficacy of zinc phosphide (ZnP), the only registered broadacre control agent for mice, is reported as increasingly variable. Have mice become less sensitive over time or are they taking a sub-lethal dose and developing aversion? In this laboratory study, the sensitivity of mice (wild caught; outbred laboratory strain) was assessed using oral gavage of a range of ZnP concentrations. The estimated LD50 values (72–79 mg ZnP/kg body weight) were similar for each mouse group but are significantly higher than previously reported. The willingness of mice to consume ZnP-coated grains was determined. ZnP-coated grains (50 g ZnP/kg grain) presented in the absence of alternative food were consumed and 94% of wild mice died. Mice provided with alternative food and ZnP-coated wheat grains (either 25 or 50 g ZnP/kg grain) consumed toxic and non-toxic grains, and mortality was lower (33–55%). If a sublethal amount of ZnP-coated grain was consumed, aversion occurred, mostly when alternative food was present. The sensitivity of wild house mice to ZnP in Australia is significantly lower than previously assumed. Under laboratory conditions, ZnP-coated grains coated with a new higher dose (50 g ZnP/kg grain) were readily consumed. Consumption of toxic grain occurred when alternative food was available but was decreased. Our unambiguous findings for house mice indicate a re-assessment of the ZnP loading for baits used for control of many rodents around the world may be warranted.  相似文献   
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A root rot of cabbage is reported from South Africa. The causal pathogen was identified as Phytophthora drechsleri , based on morphological characters and electrophoretic patterns of soluble proteins.  相似文献   
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The effects of the herbicide isouron and of its plant degradation products designated as metabolite l {N-[5-(1,1-dimethylethyl)-3-isoxazolyl]-N-methylurea} and metabolite 2 {N-[5-(1,1-dimethylethyl)-3-isoxazolyl]-urea} on the metabolism of enzymatically isolated leaf cells of soybean [Glycine max (L.) Merr., cv. Essex] were compared under laboratory conditions. Photosynthesis, protein synthesis, ribonucleic acid synthesis, and lipid synthesis were assayed by the incorporation of NaH14CO3, [14C]-leucine, [14C]-uracil, and [14C]-acetate, respectively, into the isolated cells. Time-course and concentration studies included incubation periods of 30, 60, and 120 min and concentrations of 0.1, 1, 10 and 100 μM of the three herbicides. The urea derivative of isouron (metabolite 2) was the least active of the three compounds. The activity of the mono-methylated derivative of isouron (metabolite 1) was comparable to that of isouron and the sensitivity of the four processes to both chemicals decreased in the order: photosynthesis > ribonucleic acid synthesis > lipid synthesis > protein synthesis. The concentration of isouron that caused a 50% inhibition of photosynthesis of the isolated soybean leaf cells was calculated at 0.51 μM. The effects of isouron and metabolite 1 on photosynthesis, lipid and RNA synthesis appeared to be independent of incubation lime as maximal inhibition occurred within 30 min. Inhibition of protein synthesis by both chemicals was time-dependent, increasing in magnitude with concomitant increases in incubation time.  相似文献   
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In the early spring of 1992, plum pox-like viruses (PPLVs) were detected by standard ELISA in some Prunus species. The isolates reacted positively with plum pox potyvirus (PPV) antisera in immunosorbent electron microscopy and Western blot analysis. In Western blot analyses, bands associated with the coat protein subunits of the PPLVs were 48–56 kDa, whereas bands associated with the coat protein subunits of known PPV isolates were 32–37 kDa in size. Also, the PPLVs differed from known PPV isolates in their symptoms on woody and herbaceous indicators, and in their herbaceous host range. None of these PPLVs appears to be an isolate of PPV.  相似文献   
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The host range of beet necrotic yellow vein virus (BNYVV) and Polymyxa betae was determined by growing plants in naturally infested soils from rhizomania outbreaks in England. Apart from Beta vulgaris , plant species infected by BNYVV were included in the families Chenopodiaceae ( Atriplex patula, Chenopodium bonus-henricus, C. hybridum, C. polyspermum and Spinacia oleracea ), Amaranthaceae ( Amaranthus retroflexus ) and Caryophyllaceae ( Silene alba, S. vulgaris, S. noctiflora and Stellaria graminea ). Only P. betae isolates from B. vulgaris, C. polyspermum and S. oleracea were found to be able to transmit BNYVV back to sugar beet. When a range of weed plants from infected fields were tested, none were found to be infected by BNYVV. Therefore, it seems likely that the weed hosts play only a minor role in the spread of rhizomania disease compared to that of sugar beet, other Beta vulgaris crop types or spinach.  相似文献   
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Twenty-two young cross-bred swine were treated either intravenously or orally with potassium penicillin G. The pharmacokinetics of penicillin G were determined in plasma and tissues. The plasma half-life of penicillin G in swine was found to be 19.45±1.69 min, and the distribution and elimination kinetics were found to fit a classical two-compartment model. The volume of distribution was found to be 0.53±0.12 1/kg, and the body clearance was found to be 19.06±5.06 ml/min/kg which exceeded the effective renal plasma flow of 16.50±2.73 ml/min/kg, suggesting that the drug was eliminated both by tubular excretion and glomerular filtration. The elimination rate constants (Beta) for the major organs were as follows: muscle, 0.00343 min-1; lung, 0.0310 min-1; fat, 0.0394 min-1; and kidney, 0.0213 min-1, which compared favorably with the elimination rate constant found in plasma (0.0320 min-1). These values were found to be significantly similar at the level of P < 0.005 in muscle, spleen and fat, and at a level of P < 0.025 in lung tissue. The data indicates that blood plasma would be a satisfactory body fluid for estimating this drug in tissue.  相似文献   
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