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131.
Cognitive Structure and Informant Accuracy 总被引:5,自引:0,他引:5
The problem of informant accuracy is examined in light of principles of memory organization from cognitive psychology. These principles turn out to be powerful, not only in explaining overall patterns of informant error, but in predicting details about the types of errors made. Predictions are made in terms both of different kinds of informants and different kinds of objects. All the predictions are strongly supported by the data. Finally, in the light of these results, two strategies are developed. The "best" informants, it seems, can be used to reveal long-range stable patterns of events, and the "worst" informants can be used to reveal the details of a particular event of special interest. 相似文献
132.
133.
The binding of radiolabeled epidermal growth factor (EGF) to immobilized A-431 target cell membranes coupled to polyvinyl chloride microtiter wells is described. Saturation curves and Scatchard analysis of the data indicate that the observed binding parameters are consistent with those previously reported. Binding capacity of the membranes are approx. 6.6 pmol EGF per mg membrane protein. Kinetics of 125I-EGF binding were slower, however, than reported for binding to membranes in suspension, although binding constants were not greatly different. The high- and low-affinity binding constants for 125I-EGF were calculated to be approximately 1 · 1012 M?1 and 2.5 · 109 M?1, respectively. Application of this technique in a competitive binding assay requires no more than 2.5 μg of membrane protein per assay, is essentially complete after 60 min, and facilitates screening of a large number of samples in a short time. Therefore, this will assist in the evaluation and quantitation of EGF and EGF-related transforming growth factor activity in physiological fluids. This technique may also be applied to analyses of other hormone-receptor systems. 相似文献
134.
135.
Kubica N Bolster DR Farrell PA Kimball SR Jefferson LS 《The Journal of biological chemistry》2005,280(9):7570-7580
The contribution of mammalian target of rapamycin (mTOR) signaling to the resistance exercise-induced stimulation of skeletal muscle protein synthesis was assessed by administering rapamycin to Sprague-Dawley rats 2 h prior to a bout of resistance exercise. Animals were sacrificed 16 h postexercise, and gastrocnemius protein synthesis, mTOR signaling, and biomarkers of translation initiation were assessed. Exercise stimulated the rate of protein synthesis; however, this effect was prevented by pretreatment with rapamycin. The stimulation of protein synthesis was mediated by an increase in translation initiation, since exercise caused an increase in polysome aggregation that was abrogated by rapamycin administration. Taken together, the data suggest that the effect of rapamycin was not mediated by reduced phosphorylation of eukaryotic initiation factor 4E (eIF4E) binding protein 1 (BP1), because exercise did not cause a significant change in 4E-BP1(Thr-70) phosphorylation, 4E-BP1-eIF4E association, or eIF4F complex assembly concomitant with increased protein synthetic rates. Alternatively, there was a rapamycin-sensitive decrease in relative eIF2Bepsilon(Ser-535) phosphorylation that was explained by a significant increase in the expression of eIF2Bepsilon protein. The proportion of eIF2Bepsilon mRNA in polysomes was increased following exercise, an effect that was prevented by rapamycin treatment, suggesting that the increase in eIF2Bepsilon protein expression was mediated by an mTOR-dependent increase in translation of the mRNA encoding the protein. The increase in eIF2Bepsilon mRNA translation and protein abundance occurred independent of similar changes in other eIF2B subunits. These data suggest a novel link between mTOR signaling and eIF2Bepsilon mRNA translation that could contribute to the stimulation of protein synthesis following acute resistance exercise. 相似文献
136.
We recently discovered and reported that C57BL/6J-bgJ/bgJ (beige-J) mice have a deficiency in their analgesic response to intracerebroventricularly-administered morphine in the tail-flick test. Postulating a link between these findings and the known immunological defect of beige-J mice (Chediak-Higashi syndrome), we examined the effect of splenectomy on beige-J mice and the adoptive transfer of their mononuclear spleen cells to normal littermate controls (2 x 10(7) cells via tail vein). Eight days after these interventions, the splenectomized beige-J mice responded nearly as well as normal mice to centrally administered morphine in the tail-flick test. The adoptive transfer recipients, in contrast, nearly completely lost their response to the analgesic action of morphine in this test. From the combined results, the spleen appears to be a significant factor in the analgesic defect of beige-J mice and, furthermore, mononuclear splenocytes appear to be the source of a substance that can transfer this defect to otherwise normal animals. 相似文献
137.
Next generation of elevated [CO2] experiments with crops: a critical investment for feeding the future world 总被引:1,自引:0,他引:1
Ainsworth EA Beier C Calfapietra C Ceulemans R Durand-Tardif M Farquhar GD Godbold DL Hendrey GR Hickler T Kaduk J Karnosky DF Kimball BA Körner C Koornneef M Lafarge T Leakey AD Lewin KF Long SP Manderscheid R McNeil DL Mies TA Miglietta F Morgan JA Nagy J Norby RJ Norton RM Percy KE Rogers A Soussana JF Stitt M Weigel HJ White JW 《Plant, cell & environment》2008,31(9):1317-1324
A rising global population and demand for protein-rich diets are increasing pressure to maximize agricultural productivity. Rising atmospheric [CO2 ] is altering global temperature and precipitation patterns, which challenges agricultural productivity. While rising [CO2 ] provides a unique opportunity to increase the productivity of C3 crops, average yield stimulation observed to date is well below potential gains. Thus, there is room for improving productivity. However, only a fraction of available germplasm of crops has been tested for CO2 responsiveness. Yield is a complex phenotypic trait determined by the interactions of a genotype with the environment. Selection of promising genotypes and characterization of response mechanisms will only be effective if crop improvement and systems biology approaches are closely linked to production environments, that is, on the farm within major growing regions. Free air CO2 enrichment (FACE) experiments can provide the platform upon which to conduct genetic screening and elucidate the inheritance and mechanisms that underlie genotypic differences in productivity under elevated [CO2 ]. We propose a new generation of large-scale, low-cost per unit area FACE experiments to identify the most CO2 -responsive genotypes and provide starting lines for future breeding programmes. This is necessary if we are to realize the potential for yield gains in the future. 相似文献
138.
The murid rodent subfamily Sigmodontinae contains 79 genera which are
distributed throughout the New World. The time of arrival of the first
sigmodontines in South America and the estimated divergence time(s) of the
different lineages of South American sigmodontines have been controversial
due to the lack of a good fossil record and the immense number of extant
species. The "early-arrival hypothesis" states that the sigmodontines must
have arrived in South America no later than the early Miocene, at least 20
MYA, in order to account for their vast present-day diversity, whereas the
"late-arrival hypothesis" includes the sigmodontines as part of the
Plio-Pleistocene Great American Interchange, which occurred approximately
3.5 MYA. The phylogenetic relationships among 33 of these genera were
reconstructed using mitochondrial DNA (mtDNA) sequence data from the ND3,
ND4L, arginine tRNA, and ND4 genes, which we show to be evolving at the
same rate. A molecular clock was calibrated for these genes using published
fossil dates, and the genetic distances were estimated from the DNA
sequences in this study. The molecular clock was used to estimate the dates
of the South American sigmodontine origin and the main sigmodontine
radiation in order to evaluate the "early-" and "late-arrival" scenarios.
We estimate the time of the sigmodontine invasion of South America as
between approximately 5 and 9 MYA, supporting neither of the scenarios but
suggesting two possible models in which the invading lineage was either (1)
ancestral to the oryzomyines, akodonts, and phyllotines or (2) ancestral to
the akodonts and phyllotines and accompanied by the oryzomyines. The
sigmodontine invasion of South America provides an example of the advantage
afforded to a lineage by the fortuitous invasion of a previously
unexploited habitat, in this case an entire continent.
相似文献
139.
140.
Substance P, neurokinin A, and neurokinin B induce generation of IL-1-like activity in P388D1 cells. Possible relevance to arthritic disease 总被引:7,自引:0,他引:7
E S Kimball F J Persico J L Vaught 《Journal of immunology (Baltimore, Md. : 1950)》1988,141(10):3564-3569
Near nanomolar concentrations of substance P induce production of IL-1 or an IL-1-like activity in the mouse macrophage cell line P388D1. Moreover, this could be accomplished with the carboxyl-terminal octapeptide substance P4-11, and could be inhibited with the substance P antagonist [D-Pro2, D-Trp7,9]-substance P. Two other mammalian neurokinins, neurokinin A and neurokinin B, were also found to induce secretion of IL-1-like activity in P388D1 cells. These findings suggest that activation of immune cells by neuromodulators can contribute to the maintenance of the chronic inflammatory state and the immunopathology observed in arthritic disease mediated by IL-1. The results also suggest that one approach to the treatment of rheumatoid arthritis might be to attempt to inhibit the local effects of immuno-modulatory neuropeptides, specifically the neurokinins, in affected joints. 相似文献