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  • Physiology & Biochemistry  (18)
  • Cooperatives  (8)
  • Oxford University Press  (26)
  • American Physical Society
  • 1
    Publication Date: 2016-06-30
    Description: We screened for a gene that inhibits streptomycin production in Streptomyces griseus when it is introduced on a high-copy-number plasmid pIJ702, and obtained a plasmid pKM545. The introduction of pKM545 abolished streptomycin production on all media tested including YMP-sugar and Nutrient broth. S1 protection analysis demonstrated that the introduction of this plasmid downregulated the transcriptional activity of the promoter preceding strR , the pathway-specific transcriptional regulator for streptomycin biosynthesis. The 2.8-kb Bam HI fragment cloned onto pKM545 contained two coding sequences SGR_5442 and 5443. These coding sequences and the two downstream ones (SGR_5444 and 5445) constituted a possible operon structure designated to be rspABCD (regulation of streptomycin production). RspB and RspC exhibited a marked similarity with an ATP-binding domain and a membrane-associating domain of an ABC-2 type transporter, respectively, suggesting that the Rsp proteins comprise a membrane exporter. The gene cluster consisting of the rsp operon and the upstream divergent small coding sequence (SGR_5441) was widely distributed to Streptomyces genome. An rspB mutant of S. griseus produced 3-fold streptomycin of the parental strain in YMP liquid medium. The evidence implies that the Rsp translocator is involved in the export of a substance that specifies the expression level of streptomycin biosynthesis genes in S. griseus .
    Keywords: Physiology & Biochemistry
    Print ISSN: 0378-1097
    Electronic ISSN: 1574-6968
    Topics: Biology
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  • 2
    Publication Date: 2017-01-19
    Description: Although nitric oxide (NO) is an important signaling molecule in bacteria and higher organisms, excessive intracellular NO is highly reactive and dangerous. Therefore, living cells need strict regulation systems for cellular NO homeostasis. Recently, we discovered that Streptomyces coelicolor A3(2) retains the nitrogen oxide cycle (NO 3 – -〉NO 2 – -〉NO-〉NO 3 – ) and nitrite removal system. The nitrogen oxide cycle regulates cellular NO levels, thereby controlling secondary metabolism initiation (red-pigmented antibiotic, RED production) and morphological differentiation. Nitrite induces gene expression in neighboring cells, suggesting another role for this cycle as a producer of transmittable intercellular communication molecules. Here, we demonstrated that ammonium-producing nitrite reductase (NirBD) is involved in regulating NO homeostasis in S. coelicolor A3(2). NirBD was constitutively produced in culture independently of GlnR, a known transcriptional factor. NirBD cleared the accumulated nitrite from the medium. Nir deletion mutants showed increased NO-dependent gene expression at later culture stages, whereas the wild-type M145 showed decreased expression, suggesting that high NO concentration was maintained in the mutant. Moreover, the nir deletion mutant produced more RED than that produced by the wild-type M145. These results suggest that NO 2 – removal by NirBD is important to regulate NO homeostasis and to complete NO signaling in S. coelicolor .
    Keywords: Physiology & Biochemistry
    Print ISSN: 0378-1097
    Electronic ISSN: 1574-6968
    Topics: Biology
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  • 3
    Publication Date: 2016-05-12
    Description: Clostridium thermocellum and Thermoanaerobacterium saccharolyticum are bacteria under investigation for production of biofuels from plant biomass. Thermoanaerobacterium saccharolyticum has been engineered to produce ethanol at high yield (〉90% of theoretical) and titer (〉70 g/l). Efforts to engineer C. thermocellum have not, to date, been as successful, and efforts are underway to transfer the ethanol production pathway from T. saccharolyticum to C. thermocellum . One potential challenge in transferring metabolic pathways is the possibility of incompatible levels of nicotinamide cofactors. These cofactors (NAD + , NADH, NADP + and NADPH) and their oxidation state are important in the context of microbial redox metabolism. In this study we directly measured the concentrations and reduced oxidized ratios of these cofactors in a number of strains of C. thermocellum and T. saccharolyticum by using acid/base extraction and enzymatic assays. We found that cofactor ratios are maintained in a fairly narrow range, regardless of the metabolic network modifications considered. We have found that the ratios are similar in both organisms, which is a relevant observation in the context of transferring the T. saccharolyticum ethanol production pathway to C. thermocellum .
    Keywords: Physiology & Biochemistry
    Print ISSN: 0378-1097
    Electronic ISSN: 1574-6968
    Topics: Biology
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  • 4
    Publication Date: 2015-05-12
    Description: Farm households in developing countries generally allocate a major portion of their resources to staple food production, mainly for self-consumption. Hence, many of them are more or less delinked from the market. It is well recognized, however, that market participation is crucial for farm households to ensure a flow of cash income, leading to poverty alleviation and improved livelihoods. Thus, it is meaningful to understand what factors affect farm households' decision to sell food crops, which is important for strengthening their linkages with markets. The empirical literature on impacts of market linkages has seldom focused on the determinants of market participation. Using rice farm households in Bangladesh and applying a double-hurdle model, this article demonstrates that the provision of general education and the development of agricultural infrastructure such as irrigation facilities can strengthen the market linkages of farm households by enhancing their marketable surplus through increased production. By contrast, rainfall beyond the optimum level, drought spells, and flood incidences can weaken market linkages by reducing their marketable surplus through decreased production. Specific policies such as investment in general education are drawn up based on the findings.
    Keywords: C24 - Truncated and Censored Models, D01 - Microeconomic Behavior: Underlying Principles, D13 - Household Production and Intrahousehold Allocation, Q12 - Micro Analysis of Farm Firms, Farm Households, and Farm Input Markets, Q13 - Agricultural Markets and Marketing ; Cooperatives ; Agribusiness
    Print ISSN: 2040-5790
    Electronic ISSN: 2040-5804
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Economics
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  • 5
    Publication Date: 2016-03-31
    Description: Thinly traded agricultural commodity markets are a concern for farmers and policy markers due to the belief that prices in these settings will be highly volatile, subject to manipulation, and incapable of efficiently allocating resources. Analysis of thin agricultural markets has to date been impeded by lack of an appropriate analytical framework from which to study their behavior. In this paper we propose the modern agricultural markets (MAM) framework as an appropriate paradigm through which to view and evaluate thin markets. We argue that thinly traded markets that meet key conditions required for a MAM will generate maximum economic surplus and enable farmers to earn at least a competitive return on their investments. In the absence of these conditions, however, the concerns known as the "thin market problem" have validity. We set forth the MAM framework, interpret it in a thin-market context, and conduct several brief case studies of thin markets to illustrate use of the approach and draw some key inferences about these markets' behavior. The analysis indicates that appropriate government policies directed to thin markets are those that facilitate their convergence to MAM status, but in reality key policies under recent consideration would have the opposite effect.
    Keywords: L10 - General, Q13 - Agricultural Markets and Marketing ; Cooperatives ; Agribusiness
    Print ISSN: 0002-9092
    Electronic ISSN: 1467-8276
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Economics
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  • 6
    Publication Date: 2015-07-10
    Description: In many developing countries, supermarkets are expanding rapidly. This affects farmers’ marketing options. Previous studies have analyzed welfare effects of smallholder participation in supermarket channels from a static perspective, using cross-section data. We develop a conceptual framework and use panel data to better understand participation and impact dynamics. The analysis focuses on vegetable producers in Kenya. Participation in supermarket channels is associated with income gains. However, many farmers have dropped out of the supermarket channel due to various constraints. The initial income gains cannot be sustained when returning to the traditional market. Organizational support may be needed to avoid widening income disparities.
    Keywords: L24 - Contracting Out ; Joint Ventures ; Technology Licensing, O12 - Microeconomic Analyses of Economic Development, O13 - Agriculture ; Natural Resources ; Energy ; Environment ; Other Primary Products, Q12 - Micro Analysis of Farm Firms, Farm Households, and Farm Input Markets, Q13 - Agricultural Markets and Marketing ; Cooperatives ; Agribusiness, Q18 - Agricultural Policy ; Food Policy
    Print ISSN: 0002-9092
    Electronic ISSN: 1467-8276
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Economics
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  • 7
    Publication Date: 2016-08-18
    Description: The effect of fructose 1,6-bisphosphate (Fru 1,6-P 2 ) on the regulatory enzymes of pentose phosphate pathway of Escherichia coli was examined. Fru 1,6-P 2 inhibited E. coli transaldolase (EC 2.2.1.2) competitively against fructose 6-phosphate and uncompetitively against erythrose 4-phosphate, whereas Fru 1,6-P 2 did not affect glucose 6-phosphate dehydrogenase (EC 1.1.1.49) and 6-phosphogluconate dehydrogenase (EC 1.1.1.44). Kinetic results can be explained by assuming that transaldolase has two kinds of binding sites for Fru 1,6-P 2 : a competitive binding site for fructose 6-phosphate and a second binding site on the enzyme-erythrose 4-phosphate complex. Fru 1,6-P 2 increased resulting from the stimulation of glycolysis, can inhibit transaldolase and further participates in the elevation of the concentration of ribose 5-phosphate that can be preferentially utilized for anabolic reaction in exponential phase of E. coli .
    Keywords: Physiology & Biochemistry
    Print ISSN: 0378-1097
    Electronic ISSN: 1574-6968
    Topics: Biology
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  • 8
    Publication Date: 2016-08-11
    Description: Geobacter sulfurreducens is an anaerobic soil bacterium that is involved in biogeochemical cycles of elements such as Fe and Mn. Although significant progress has been made in the understanding of the electron transfer processes in G. sulfurreducens , little is known about the regulatory mechanisms involved in their control. To expand the study of gene regulation in G. sulfurreducens , we carried out a genome-wide identification of transcription start sites (TSS) by 5'RACE and by deep RNA sequencing of primary mRNAs in two growth conditions. TSSs were identified along G. sulfurreducens genome and over 50% of them were located in the upstream region of the associated gene, and in some cases we detected genes with more than one TSS. Our global mapping of TSSs contributes with valuable information, which is needed for the study of transcript structure and transcription regulation signals and can ultimately contribute to the understanding of transcription initiation phenomena in G. sulfurreducens .
    Keywords: Physiology & Biochemistry
    Print ISSN: 0378-1097
    Electronic ISSN: 1574-6968
    Topics: Biology
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  • 9
    Publication Date: 2015-07-10
    Description: We argue that farm survival is influenced by neighboring farmers’ characteristics and, in particular, by the direct payments neighboring farmers receive. The article shows empirically that these interdependencies are crucial for an assessment of the effects of direct payments on farm survival. Using spatially explicit farm-level data for nearly all Norwegian farms, a spatial probit model is estimated to explain farm survival from 1999 to 2009 controlling for spatial farm interdependence. We show that ignoring spatial interdependencies between farms leads to a substantial overestimation of the effects of direct payments on farm survival. To our knowledge, this article is the first attempt to empirically analyze the importance of neighboring interdependencies for the effects of direct payments on farm survival.
    Keywords: C21 - Cross-Sectional Models ; Spatial Models ; Treatment Effect Models, C25 - Discrete Regression and Qualitative Choice Models, Q12 - Micro Analysis of Farm Firms, Farm Households, and Farm Input Markets, Q13 - Agricultural Markets and Marketing ; Cooperatives ; Agribusiness
    Print ISSN: 0002-9092
    Electronic ISSN: 1467-8276
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Economics
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  • 10
    Publication Date: 2016-02-03
    Description: In this article, we provide an overview of the extensive literature on the impact of weather and climate on grapes and wine, with the goal of identifying how climate change is likely to affect their production. We first discuss the physical impact of weather on vine phenology (i.e., the timing of biological events such as bud break or flowering), berry composition, and yields. Then we examine the economic literature that measures the effects of temperature on wine quality, prices, costs, and profits and, based on this review, infer how climate change will affect these variables. We also describe what has been learned thus far about possible adaptation strategies for grape growers that would allow them to mitigate the economic effects of climate change. We conclude that climate change is likely to produce both winners and losers, with the winners being those located closer to the North and South Poles. There are also likely to be some substantial short-run costs as growers adapt to climate change. Nevertheless, wine making has survived through thousands of years of recorded history, a history that has included significant climate changes. ( JEL : Q13, Q18, Q54)
    Keywords: Q13 - Agricultural Markets and Marketing ; Cooperatives ; Agribusiness, Q18 - Agricultural Policy ; Food Policy, Q54 - Climate ; Natural Disasters ; Global Warming
    Print ISSN: 1750-6816
    Electronic ISSN: 1750-6824
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Political Science , Economics
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