922 resultados para Tobacco farms
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Includes an annual Outlook issue.
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Thesis (Master's)--University of Washington, 2016-06
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Thesis (Master's)--University of Washington, 2016-06
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Thesis (Master's)--University of Washington, 2016-06
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Thesis (Master's)--University of Washington, 2016-06
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Nitrifying bacteria were selected from shrimp farm water and sediment (natural seed) in Thailand and from commercial seed cultures. The microbial consortia from each source giving the best ammonia removal during batch culture pre-enrichments were used as inocula for two sequencing batch reactors (SBRs). Nitrifiers were cultivated in the SBRs with 100 mg NH4-N/I and artificial wastewater containing 25 ppt salinity. The two SBRs were operated at a 7 d hydraulic retention time (HRT) for 77 d after which the HRT was reduced to 3.5 d. The amounts of ammonia removed from the influent by microorganisms sourced from the natural seed were 85% and 92% for the 7 d HIRT and the 3.5 d HRT, respectively. The ammonia removals of microbial consortia from the commercial seed were 71% and 83% for these HRTs respectively. The quantity of ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) was determined in the SBRs using the most probable number (MPN) technique. Both AOB and NOB increased in number over the long-term operation of both SBRs. According to quantitative fluorescence in situ hybridisation (FISH) probing, AOB from the natural seed and commercial seed comprised 21 +/- 2% and 30 +/- 2%, respectively of all bacteria. NOB could not be detected with currently-reported FISH probes, suggesting that novel NOB were enriched from both sources. Taken collectively, the results from this study provide an indication that the nitrifiers from shrimp farm sources are more effective at ammonia removal than those from commercial seed cultures.
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The molecular mechanisms that regulate the transcription of key developmental genes involved in shoot organogenesis have yet to be fully elucidated. However, it is clear that plant growth regulators, such as cytokinin, play a critical role in the differentiation of adventitious shoots. In Nicotiana tabacum zz100 leaf discs, high frequency shoot formation could be induced with 5 muM of the cytokinin N-6-benzyladenine (BA). Increasing the exogenous BA concentration to greater than 20 muM resulted in stunted explants with abnormal shoot morphology and altered mineral composition. Explants with abnormal shoots did not appear to be hyperhydric. Abnormalities were, however, associated with an increase in the expression of a knotted1-type homeobox gene (TobH1) isolated from normal shoot-forming cultures. The results suggest that the development of cytokinin-induced abnormal shoot morphology possibly involves changes in TobH1 gene expression.
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The dopamine D4 receptor gene contains a polymorphic sequence consisting of a variable number of 48-base-pair (bp) repeats, and there have been a number of reports that this polymorphism is associated with variation in novelty seeking or in substance abuse and addictive behaviors. In this study we have assessed the linkage and association of DRD4 genotype with novelty seeking, alcohol use, and smoking in a sample of 377 dizygotic twin pairs and 15 single twins recruited from the Australian Twin Registry (ATR). We found no evidence of linkage or association of the DRD4 locus with any of the phenotypes. We made use of repeated measures for some phenotypes to increase power by multivariate genetic analysis, but allelic effects were still non-significant. Specifically, it has been suggested that the DRD4 7-repeat allele is associated with increased novelty seeking in males but we found no evidence for this, despite considerable power to do so. We conclude that DRD4 variation does not have an effect on use of alcohol and the problems that arise from it, on smoking, or on novelty seeking behavior. (C) 2003 Wiley-Liss, Inc.
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1 Accurate assessment of the impact of natural enemies on pest populations is fundamental to the design of robust integrated pest management programmes. In most situations, diseases, predators and parasitoids act contemporaneously on insect pest populations and the impact of individual natural enemies, or specific groups of natural enemies, is difficult to interpret. These problems are exacerbated in agro-ecosystems that are frequently disrupted by the application of insecticides. 2 A combination of life-table and natural enemy exclusion techniques was utilized to develop a method for the assessment of the impact of endemic natural enemies on Plutella xylostella populations on commercial Brassica farms. 3 At two of the experimental sites, natural enemies had no impact on P. xylostella survival, at two other sites, natural enemy impact was low but, at a fifth site, natural enemies drastically reduced the P. xylostella population. 4 The calculation of marginal death rates and associated k-values allowed the comparison of mortality factors between experimental sites, and indicated that larval disappearance was consistently the most important mortality factor, followed by egg disappearance, larval parasitism and pupal parasitism. The appropriateness of the methods and assumptions made to calculate the marginal death rates are discussed. 5 The technique represents a robust and easily repeatable method for the analysis of the activity of natural enemies of P. xylostella, which could be adapted for the study of other phytophagous pests.
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Glutamate dehydrogenase (GDH; EC 1.4.1.2-1.4.1.4) catalyses in vitro the reversible amination of 2-oxoglutarate to glutamate. In vascular plants the in vivo direction(s) of the GDH reaction and hence the physiological role(s) of this enzyme remain obscure. A phylogenetic analysis identified two clearly separated groups of higher-plant GDH genes encoding either the alpha- or beta-subunit of the GDH holoenzyme. To help clarify the physiological role(s) of GDH, tobacco (Nicotiana tabacum L.) was transformed with either an antisense or sense copy of a beta-subunit gene, and transgenic plants recovered with between 0.5- and 34-times normal leaf GDH activity. This large modulation of GDH activity (shown to be via alteration of beta-subunit levels) had little effect on leaf ammonium or the leaf free amino acid pool, except that a large increase in GDH activity was associated with a significant decrease in leaf Asp (similar to 51%, P=0.0045). Similarly, plant growth and development were not affected, suggesting that a large modulation of GDH beta-subunit titre does not affect plant viability under the ideal growing conditions employed. Reduction of GDH activity and protein levels in an antisense line was associated with a large increase in transcripts of a beta-subunit gene, suggesting that the reduction in beta-subunit levels might have been due to translational inhibition. In another experiment designed to detect post-translational up-regulation of GDH activity, GDH over-expressing plants were subjected to prolonged dark-stress. GDH activity increased, but this was found to be due more likely to resistance of the GDH protein to stress-induced proteolysis, rather than to post-translational up-regulation.
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In this study, the human cytochrome P450 (CYP) 2A6 was used in order to modify the alkaloid production of tobacco plants. The cDNA for human CYP2A6 was placed under the control of the constitutive 35S promoter and transferred into Nicotiana tabacum via Agrobacterium-mediated transformation. Transgenic plants showed formation of the recombinant CYP2A6 enzyme but no obvious phenotypic changes. Unlike wild-type tobacco, the transgenic plants accumulated cotinine, a metabolite which is usually formed from nicotine in humans. This result substantiates that metabolic engineering of the plant secondary metabolism via mammalian P450 enzymes is possible in vivo. (c) 2005 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.
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In this paper risk factors for the introduction of IBR, BVD, Salmonella and Johne's disease to cattle farms are reported. Two sources of information were used: literature was searched systematically and an expert opinion workshop was held. The findings from both indicate that direct contact between cattle is an important risk factor. Indirect and occasional contact is considered of less importance. Therefore, in the development of biosecurity programmes for cattle farms emphasis should be put on preventing direct contact with cattle from outside the herd.
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Background: Costs of tobacco-related disease can be useful evidence to support tobacco control. In Hong Kong we now have locally derived data on the risks of smoking, including passive smoking. Aim: To estimate the health-related costs of tobacco from both active and passive smoking. Methods: Using local data, we estimated active and passive smoking-attributable mortality, hospital admissions, outpatient, emergency and general practitioner visits for adults and children, use of nursing homes and domestic help, time lost from work due to illness and premature mortality in the productive years. Morbidity risk data were used where possible but otherwise estimates based on mortality risks were used. Utilisation was valued at unit costs or from survey data. Work time lost was valued at the median wage and an additional costing included a value of US$1.3 million for a life lost. Results: In the Hong Kong population of 6.5 million in 1998, the annual value of direct medical costs, long term care and productivity loss was US$532 million for active smoking and US$156 million for passive smoking; passive smoking accounted for 23% of the total costs. Adding the value of attributable lives lost brought the annual cost to US$9.4 billion. Conclusion: The health costs of tobacco use are high and represent a net loss to society. Passive smoking increases these costs by at least a quarter. This quantification of the costs of tobacco provides strong motivation for legislative action on smoke-free areas in the Asia Pacific Region and elsewhere.