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Oncogenic avian retroviruses, such as Rous sarcoma virus (RSV) and the avian leukosis viruses, contain a strong enhancer in the U3 portion of the proviral long terminal repeat (LTR). The LTRs of a second class of avian retroviruses, the endogenous viruses (ev) lack detectable enhancer activity. By creating ev-RSV hybrid LTRs, we previously demonstrated that, despite the lack of independent enhancer activity in the ev U3 region, ev LTRs contain sequences that are able to functionally replace essential enhancer domains from the RSV enhancer. A hypothesis proposed to explain these data was that ev LTRs contain a partial enhancer that includes sequences necessary but not sufficient for enhancer activity and that these sequences were complemented by RSV enhancer domains present in the original hybrid constructs to generate a functional enhancer. Studies described in this report were designed to define sequences from both the ev and RSV LTRs required to generate this composite enhancer. This was approached by generating additional ev-RSV hybrid LTRs that exchanged defined regions between ev and RSV and by directly testing the requirement for specific motifs by site-directed mutagenesis. Results obtained demonstrate that ev enhancer sequences are present in the same relative location as upstream enhancer sequences from RSV, with which they share limited sequence similarity. In addition, a 67-bp region from the internal portion of the RSV LTR that is required to complement ev enhancer sequences was identified. Finally, data showing that CArG motifs are essential for high-level activity, a finding that has not been previously demonstrated for retroviral LTRs, are presented. 相似文献
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Microfluidics: Inertial Microfluidic Cell Stretcher (iMCS): Fully Automated,High‐Throughput,and Near Real‐Time Cell Mechanotyping (Small 28/2017) 下载免费PDF全文
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Patrick J. Gray Sean D. Conklin Todor I. Todorov Sasha M. Kasko 《Food additives & contaminants. Part A, Chemistry, analysis, control, exposure & risk assessment》2016,33(1):78-85
This paper reports the effects of rinsing rice and cooking it in variable amounts of water on total arsenic, inorganic arsenic, iron, cadmium, manganese, folate, thiamin and niacin in the cooked grain. We prepared multiple rice varietals both rinsed and unrinsed and with varying amounts of cooking water. Rinsing rice before cooking has a minimal effect on the arsenic (As) content of the cooked grain, but washes enriched iron, folate, thiamin and niacin from polished and parboiled rice. Cooking rice in excess water efficiently reduces the amount of As in the cooked grain. Excess water cooking reduces average inorganic As by 40% from long grain polished, 60% from parboiled and 50% from brown rice. Iron, folate, niacin and thiamin are reduced by 50–70% for enriched polished and parboiled rice, but significantly less so for brown rice, which is not enriched. 相似文献
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SJ Benson BL Ruis AL Garbers AM Fadly KF Conklin 《Canadian Metallurgical Quarterly》1998,72(12):10301-10304
A new subgroup of avian leukosis virus (ALV) that includes a unique env gene, designated J, was identified recently in England. Sequence analysis of prototype English isolate HPRS-103 revealed several other unique genetic characteristics of this strain and provided information that it arose by recombination between exogenous and endogenous virus sequences. In the past several years, ALV J type viruses (ALV-J) have been isolated from broiler breeder flocks in the United States. We were interested in determining the relationship between the U.S. and English isolates of ALV-J. Based on sequence data from two independently derived U.S. field isolates, we conclude that the U.S. and English isolates of ALV-J derive from a common ancestor and are not the result of independent recombination events. 相似文献
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Maghasi AT Conklin SD Shtoyko T Piruska A Richardson JN Seliskar CJ Heineman WR 《Analytical chemistry》2004,76(5):1458-1465
Detection of lead and mercury by attenuated total internal reflectance spectroscopy coupled to stripping voltammetry is demonstrated. Changes in attenuation of light passing through an indium tin oxide optically transparent electrode (ITO-OTE) accompany the electrodeposition and stripping of lead and mercury on the electrode surface. The change in absorbance during stripping of electrodeposited metal constitutes the analytical response that enables detection over a range of 2.5 x 10(-7)-5 x 10(-5) and 5 x 10(-8)-5 x 10(-5) M for mercury and lead, respectively. The spectroelectrochemical responses of mercury and lead on the ITO surface are characterized and optimized with respect to solution conditions, the potential excitation signals used for deposition and stripping, and wavelength for detection. The deposited metals were examined by environmental scanning electron miscroscopy, and the electrodeposition pattern of lead and mercury was found to influence the optical response. 相似文献
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In 1991 the Environmental Protection Agency (EPA) published its revised Manual of Protective Action Guides and Protective Actions for Nuclear Incidents. The protective action guides contained in the manual represent EPA's formal recommendations to Federal, State, and local emergency response officials for protecting public health and safety during a nuclear incident. These guides are expressed in terms of the projected dose at which action(s) should be taken to reduce or eliminate that dose. In determining the appropriate values for the protective action guides, the Agency considered the following four principles: (1) acute health effects should be avoided, (2) the risk of delayed health effects should be minimized, (3) the values should not be higher than justified by a cost-benefit analysis, and (4) the risk to health from implementing the protective action should not be greater than the risk from the dose avoided. This paper examines each of these principles and their application in the selection of the evacuation and sheltering protective action guides for the early, or immediate, phase of a nuclear incident. 相似文献
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