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281.
G Srivastava B K May W H Elliott 《Biochemical and biophysical research communications》1979,90(1):42-49
Isolated liver cells were prepared from 17-day old chick embryos and incubated in Eagle's basal medium. Induction of δ-aminolevulinate synthase activity occurred immediately upon addition of allylisopropylacetamide and was totally dependent on the presence of Bt2cAMP (or cAMP) during the first 6 h of incubation. Under optimal inducing conditions in the presence of desferrioxamine mesylate and hormones, δ-aminolevulinate synthase induction occurred at rates comparable with those observed in ovo. The isolated liver cells provide a convenient experimental system for studying the effect of porphyrogenic drugs on porphyrin metabolism. 相似文献
282.
Ornella C. Weideli Jeremy J. Kiszka Philip Matich Michael R. Heithaus 《Journal of fish biology》2019,95(6):1535-1539
The effects of anticoagulant EDTA and sodium heparin (SH) on stable carbon δ13C and nitrogen δ15N isotopic values of red blood cells (RBC) and blood plasma in juvenile blacktip reef sharks Carcharhinus melanopterus were analysed. Plasma preserved with anticoagulants was not isotopically distinct from plasma stored in no-additive control tubes but RBC δ15N values exhibited small enrichments when preserved with EDTA and SH. Results suggest EDTA and SH are viable anticoagulants for stable isotopic analyses of blood fractions but further studies are advised to validate results. 相似文献
283.
Lin Zhang Daili Lei Xia Deng Fangfang Li Haikun Ji Shushen Yang 《Plant, cell & environment》2020,43(4):836-853
Drought is a major threat to wheat growth and crop productivity. However, there has been only limited success in developing drought-hardy cultivars. This lack of progress is due, at least in part, to a lack of understanding of the molecular mechanisms of drought tolerance in wheat. Here, we evaluated the potential role of three cytosolic glyceraldehyde-3-phosphate dehydrogenases (TaGAPC2/5/6) under drought stress in wheat and Arabidopsis. We found that TaGAPC2/5/6 all positively responded to drought stress via reactive oxygen species (ROS) scavenging and stomatal movement. The results of yeast co-transformation and electrophoretic mobility shift assay showed that TaWRKY33 acted as a direct regulator of TaGAPC2/5/6 genes. The dual luciferase reporter assay indicated that TaWRKY33 positively activated the expression of TaGAPC2/5/6. The results of bimolecular fluorescence complementation and yeast two-hybrid system demonstrated that TaGAPC2/5/6 interacted with phospholipase Dδ (PLDδ). We then demonstrated that TaGAPC2/5/6 positively promoted the activity of TaPLDδ in vitro and in vivo. Furthermore, lower PLDδ activity in RNAi wheat could lead to less PA accumulation, causing higher stomatal aperture sizes under drought stress. In summary, our results establish a new positive regulatory mechanism of TaGAPCs which helps wheat fine-tune their drought responses. 相似文献
284.
It’s favorable to alter KRas mutation’s location to endomembrane by interfering the binding of PDEδ (the prenyl-binding protein phosphodiesterase delta) to KRas. In the present work, the binding of four inhibitors (Deltarasin, allyl analogue, pyrazolopyridazinone derivative, and Deltazinone 1) to PDEδ is investigated with all-atom Molecular Dynamic (MD) simulations. The binding free energy calculation results reveal that van der Waals (VDW) energy provides the major force for affinity binding. Moreover, the binding energy decomposition indicates that residues R61 and I129 provide important contributions to binding energies in all systems. The conserved hydrogen bonds play crucial roles in anchoring the inhibitors to the exact site for binding. The results for conformational analysis of PDEδ/free and PDEδ/inhibitors systems show that the structures are more stable after the inhibitors’ binding to the PDEδ. It is also found that the most unstable system among four complexes is PDEδ/pyrazolopyridazinone derivative system whose α3-helix formed by the residues P113-Q116 disappears. This study may provide valuable information for the design of high potency PDEδ inhibitors.
Communicated by Ramaswamy H. Sarma 相似文献
285.
Resource partitioning is an essential mechanism enabling species coexistence. The resources that are used by an animal are linked to its morphology and ecology. Therefore, similar species should use similar resources. The ecological niche of an individual summarizes all used resources and is therefore composed of several dimensions. Many methods are established to study different dimensions of an animal's niche. The aim of this study was to demonstrate that a combination of suitable methods is needed to study spatial and dietary resource partitioning of sympatric species in detail. We hypothesized that, while each individual method might identify differences between species, the combined results of several methods will lead to a more complete picture of spatial and dietary resource partitioning. As model organisms we chose the sympatric insectivorous bat species Myotis bechsteinii, M. nattereri, and P. auritus. We examined horizontal habitat use by telemetry, vertical habitat use by measuring δ13C, trophic position by measuring δ15N in wing membrane, and diet composition by molecular fecal analysis. Our results show that each method is able to provide information about spatial/dietary resource partitioning. However, considering further dimensions by combining several methods allows a more comprehensive assessment of dietary and spatial resource partitioning in bats. 相似文献
286.
Across existing fish host–parasite literature, endoparasites were depleted in δ15N compared to their hosts, while ectoparasitic values demonstrated enrichment, depletion and equivalence relative to their hosts. δ13C enrichment varied extensively for both endo- and ectoparasites across taxa and host tissues. In our case study, sea lice (Lepeophtheirus salmonis) were enriched in δ15N relative to their farmed Atlantic salmon (Salmo salar) hosts, although the value contradicted the average that is currently assumed across the animal kingdom. Common fish lice (Argulus foliaceus) did not show a consistent trend in δ15N compared to their wild S. salar hosts. Both parasitic species had a range of δ13C enrichment patterns relative to their hosts. Farmed and wild S. salar had contrasting δ13C and δ15N, and signals varied across muscle, fin and skin within both groups. L. salmonis and A. foliaceus subsequently had unique δ13C and δ15N, and L. salmonis from opposite US coasts differed in δ15N. Given the range of enrichment patterns that were exhibited across the literature and in our study system, trophic dynamics from host to parasite do not conform to traditional prey to predator standards. Furthermore, there does not appear to be a universal enrichment pathway for δ13C nor δ15N in parasitic relationships, which emphasizes the need to investigate host–parasite linkages across species. 相似文献
287.
Deng Y Chin YW Chai HB de Blanco EC Kardono LB Riswan S Soejarto DD Farnsworth NR Kinghorn AD 《Phytochemistry letters》2011,4(3):213-217
A phytochemical investigation of the leaves of Vitex quinata (Lour.) F.N. Williams (Verbenaceae), guided by a cytotoxicity assay against the MCF-7 human breast cancer cell line, led to the isolation of a new δ-truxinate derivative (1) and a new phytonoic acid derivative (2), together with 12 known compounds. The structures of the new compounds were determined by spectroscopic methods as dimethyl 3,4,3′,4′-tetrahydroxy-δ-truxinate (1) and methyl 10R-methoxy-12-oxo-9(13),16E-phytodienoate (2), respectively. In a cytotoxicity assay, (S)-5-hydroxy-7,4′-dimethoxyflavanone (3) was found to be the sole active principle, with ED50 values of 1.1–6.7 μM, respectively, when tested against a panel of three human cancer cells. Methyl 3,4,5-O-tricaffeoyl quinate (4) showed activity in an enzyme-based ELISA NF-κB p65 assay, with an ED50 value of 10.3 μM. 相似文献
288.
随着氮沉降的不断增加以及人们对全球变化问题的日益关注, 稳定同位素技术在全球变化研究中得到广泛的应用。因为植物和土壤的氮同位素组成记录了氮循环影响因子的综合作用, 并且具有测量简单以及不受取样时间和空间限制的优点, 所以氮同位素自然丰度法被用于氮循环的研究中。该文从氮循环过程中植物和土壤的氮分馏入手, 总结国内外相关文献, 阐述了植物和土壤氮自然丰度在预测生态系统氮饱和和氮循环长期变化趋势中的应用; 总结了利用树轮δ 15N法研究氮循环过程中应该注意的事项以及目前尚未解决的问题。 相似文献
289.
Osz J Pradeau-Aubreton K Drillien R Troffer-Charlier N Kolb-Cheynel I Poterszman A Ruff M Moras D Rochel N 《Analytical biochemistry》2012,426(2):106-108
Purified protein expression level and quality are contingent upon specific host expression systems. This differential production is particularly observed for proteins of high molecular weight, hampering further structural studies. We developed an expression method aimed at producing proteins in Escherichia coli, insect, and mammalian systems. Our novel protocol was used to produce in large scale the full-length 160-kDa steroid receptor coactivator 1 (SRC-1), a coregulator of nuclear receptors. The results indicate that we can produce biologically active human SRC-1 in mammalian and insect cells in large scale. 相似文献
290.