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Nitrate reductase (NR) is rapidly inactivated by phosphorylation of serine residues in response to loss of light or reduction in CO2 levels. To identify sites within NR protein that play a role in this post-translational regulation, a heterologous expression system and an in vitro inactivation assay for Arabidopsis NR were developed. Protein extracts containing NR kinases and inhibitor proteins were prepared from an NR-defective mutant that had lesions in both the NIA1 and NIA2 NR genes of Arabidopsis. Active NR protein was produced in a Pichia pastoris expression system. Incubation of these two preparations resulted in a Mg-ATP-dependent inactivation of NR that was reversed with EDTA. Mutant forms of NR were constructed, produced in P. pastoris, and tested in the in vitro inactivation assay. Six conserved serine residues in the hinge 1 region of NR, which separates the molybdenum cofactor and heme domains, were specifically targeted for mutagenesis because they are located in a potential regulatory region identified as a target for NR kinases in spinach. A change in Ser-534 to aspartate was found to block NR inactivation; changes in the other five serines had no effect. The aspartate that replaced Ser-534 did not appear to mimic a phosphorylated serine but simply prevented the NR from being inactivated. These results identify Ser-534, located in the hinge 1 of NR and conserved among higher plants NRs, as an essential site for post-translational regulation in vitro. 相似文献
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S.R. Doctor L.J. Busse H.D. Collins S.L. Crawford L.P. van Houten 《Nuclear Engineering and Design》1985,86(1):31-38
A three-year program at the Pacific Northwest Laboratory is underway to move the synthetic aperture focusing technology from the laboratory into the field. This is a report of the first year's activities that concentrated on conducting the needed engineering for a field system. In addition, the data acquisition portion of the system was completed so that data can be collected in the field with subsequent laboratory processing. The field system specifications are given and some SAFT results are shown. 相似文献
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Administered tests of R. B. Cattel's (1965, 1971) fluid and crystallized intelligence and ergs and sentiments (e.g., Culture Fair Intelligence Test and the School Motivation Analysis Test), and the Torrance Tests of Creative Thinking to 163 9th graders. Results support the hypothesized distinction between fluid and crystallized intelligence, but they indicate that the distinction between ergs (defined as traits reflecting basic biological needs for emotional expression) and sentiments (defined as source traits which come into existence because of an individual's contacts with important cultural institutions) may be more conceptual than empirical. Multivariate analyses of these results and achievement data substantiate the importance of institutionally learned intellectual skills in both achievement and creativity. (15 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
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"As an organization of individual members, our first major source of income derives from membership dues." Major sections are: Growth in Income, Expense, and Membership; History of Dues Increases; The Journal Operations; Annual Allocation of Resources; External Grants and Contracts; Additional Operations; and Conclusion. "Just as 1962 represented our first budgeted years of over $1,000,000 in both income and expenses, 1963 will see a membership in excess of 20,000." (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
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Studied the relationship of gestalt closure tasks to hypnotizability (Harvard Group Scale of Hypnotic Susceptibility and Stanford Hypnotic Susceptibility Scale) as a test of the hypothesis that the more highly hypnotizable do better on a task of holistic visuospatial functioning than those less responsive to hypnosis. Several other cognitive tasks were included. Four studies were conducted with 125 male and 106 female high school and college students. In Study I, high hypnotizables scored significantly higher than low hypnotizables on the gestalt closure tasks, but there were no significant correlations between hypnotizability and the other cognitive tasks. In Studies II and III, females showed significant correlations between hypnotic susceptibility and gestalt closure scores. In Study IV, a significant correlation between hypnotic susceptibility and gestalt closure was found for males. Results are consistent with studies of different types of cognitive functioning (hemispheric preference, creativity, attentional distribution, imaginative involvement, and absorption), all indicating differences in cognitive abilities associated with high hypnotizability. (33 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献