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Six Friesian calves from a pedigree herd died or were killed within 1 week of birth because of progressive central nervous disease in which the only consistent lesion was cerebral oedema. The cause was citrullinaemia, resulting from an autosomally inherited dysfunction of the urea cycle enzyme arginosuccinate synthetase. Citrullinaemia was diagnosed by demonstrating markedly elevated concentrations of citrulline in the blood of one calf and in the cerebral spinal fluid of another. One of two sires used in the herd was a heterozygous carrier of the disease. Heterozygocity was demonstrated using a polymerase chain reaction/restriction endonuclease test designed to detect the genetic mutation that causes citrullinaemia in cattle. 相似文献
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Arable land in western Kenya is under considerable pressure from increasing human population. Rural households depend on farming for at least part of their livelihood, and poverty rates are among the highest in Kenya. Land is often depleted of nutrients, and for most farmers, access to inputs and markets is poor. There is a need to identify options that are manageable within the context of the farmer’s resource base and the household’s objectives that could improve farm household well-being. In this study we integrated qualitative informal participatory approaches with quantitative mathematical programming and biophysical simulation modelling. Households in four sub-locations in Vihiga District were clustered and pilot cases identified. Meetings were held with farmers to elicit their perceptions of what their ideal farm would look like, and how its performance might compare with their own farm’s performance. With farmers’ help, a range of scenarios was analysed, relating to changes in current enterprise mixes, changes in current farm sizes, and changes in prices of staples foods and cash crops. A considerable mismatch was found between farmers’ estimates of their own farm’s performance, and what was actually produced. There seems to be a threshold in farm size of 0.4 ha, below which it is very difficult for households to satisfy their income and food security objectives. Even for larger farms whose households are largely dependent on agriculture, the importance of a cash crop in the system is critical. There is a crucial role for extension services in making farmers aware of the potential impacts on farm revenue of modest changes in their farm management systems. We are monitoring nine households in the district, whose farmers have made some changes to their system in an attempt to increase household income and enhance food security. 相似文献
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Thornton TM Pedraza-Alva G Deng B Wood CD Aronshtam A Clements JL Sabio G Davis RJ Matthews DE Doble B Rincon M 《Science (New York, N.Y.)》2008,320(5876):667-670
Glycogen synthase kinase 3beta (GSK3beta) is involved in metabolism, neurodegeneration, and cancer. Inhibition of GSK3beta activity is the primary mechanism that regulates this widely expressed active kinase. Although the protein kinase Akt inhibits GSK3beta by phosphorylation at the N terminus, preventing Akt-mediated phosphorylation does not affect the cell-survival pathway activated through the GSK3beta substrate beta-catenin. Here, we show that p38 mitogen-activated protein kinase (MAPK) also inactivates GSK3beta by direct phosphorylation at its C terminus, and this inactivation can lead to an accumulation of beta-catenin. p38 MAPK-mediated phosphorylation of GSK3beta occurs primarily in the brain and thymocytes. Activation of beta-catenin-mediated signaling through GSK3beta inhibition provides a potential mechanism for p38 MAPK-mediated survival in specific tissues. 相似文献
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A new phytase expressed in yeast effectively improves the bioavailability of phytate phosphorus to weanling pigs 总被引:3,自引:0,他引:3
We have recently expressed a new phytase enzyme in a yeast system. Three experiments with a total of 140 weanling crossbred pigs were conducted to examine the efficacy of this enzyme in improving the bioavailability of phytate-P in corn-soybean meal diets to young pigs. Experiment 1 compared the efficacy of this new phytase with a commercially available phytase (Natuphos, BASF) for 4 wk at an inclusion level of 1,200 U/kg of diet. Experiment 2 compared the responses of pigs to four doses of the new phytase supplementation (300, 600, 900, and 1,200 U/kg of diet) for 4 wk. Experiment 3 compared the efficacy of this new phytase and Natuphos at a marginally optimal dose (700 U/kg of diet) for 5 wk. A group of pigs were fed the P-deficient basal diet as a negative control in Exp. 1, and a group of pigs were fed the basal diet plus .17 or .22% inorganic P as a positive control in all experiments. In Exp. 1, pigs fed the two sources of phytase had similar ADG (564 vs 567 g), gain/feed (.597 vs .589), plasma inorganic P concentrations (8.9 vs 8.4 mg/dL), and mobility scores (4.25 vs 4.46) that were higher (P < .05) than those of the negative control. In Exp. 2, plasma inorganic P concentration was a fairly linear response to the phytase dose (r > .83) at wk 1 and 2. Overall ADG of pigs also tended to increase with the phytase dose (P = .15). In Exp. 3, pigs fed the two sources of phytase had ADG (483 vs 506 g) similar to that of the positive control (508 g). These two groups also had similar plasma inorganic P concentrations (7.7 vs 7.4 mg/dL) that were lower (P < .05) than those of the positive control group (9.7 mg/dL). There was no significant effect of dietary treatments on ADFI in all three experiments. In conclusion, our new phytase was as effective as Natuphos, at the inclusion level of 700 or 1,200 U/kg of a P-deficient, corn-soybean meal diet, in improving phytate-P utilization by young pigs. 相似文献
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A combined baiting, double monoclonal antibody immunoassay was developed that allows specific and sensitive detection of the economically important soil-borne plant pathogen Rhizoctonia solani in naturally infested soils. The assay is quick, taking only three days to complete from receipt of soil samples and the immunoassay format allows recovery of Rhizoctonia isolates from colonized baits for determination of anastomosis group (AG) affiliation and pathogenicity. The assay was tested on naturally infested soils from commercial glasshouses used to grow lettuce. Using the immunoassay, conventional anastomosis tests against known AG isolates, and pathogenicity tests, it was shown that R. solani isolates recovered from soil samples were pathogenic towards lettuce and belonged to AG4. Furthermore, those isolates that exhibited strong pathogenicity towards lettuce were recovered from sites that had experienced severe Rhizoctonia damage in previous lettuce crops. The possibility of developing a preplanting test to predict damage to specific crop plants due to the presence of particular AGs in the soil is discussed. 相似文献