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91.
92.
Does photorespiration protect the photosynthetic apparatus in french bean leaves from photoinhibition during drought stress? 总被引:15,自引:0,他引:15
Dithiothreitol (DTT), an inhibitor of violaxanthin de-epoxidation and zeaxanthin formation in chloroplasts, inhibited blue-light-stimulated stomatal opening in epidermal peels of Vicia faba L. in a concentration-dependent fashion. Complete inhibition was observed at 3 mM DTT. The DTT effect was specific for the stomatal response to blue light, and the red-light-stimulated opening, which depends on photosynthetic reactions in the guard cells, was unaffected. Preirradiation of stomata in epidermal peels with increasing photon fluence rates of red light, prior to an incubation in 10 mol·m-2·s-1 of blue light and 100 mol·m-2·s-1 red light, resulted in a DTT-sensitive, blue-light-stimulated opening that was proportional to the fluence rate of the red light pre-treatment. Guard cells in epidermal peels and guard-cell protoplasts irradiated with red light showed increases in their zeaxanthin content that depended on the fluence rate of red light, or on the incubation time. The increases in zeaxanthin concentration were inhibited by DTT. The obtained results indicate that zeaxanthin could function as a photoreceptor mediating the stomatal responses to blue light.Abbreviation DTT
dithiothreitol
This work was supported by grants from the National Science Foundation and the US Department of Energy to E.Z. 相似文献
93.
Nery N. Lima Carem G.V. Rechia Joana Lea M.S. Ganter Fany Reicher Maria Rita Sierakowski 《International journal of biological macromolecules》1995,17(6):413-415
On aqueous extraction, Hymenaea courbaril var. stilbocarpa, known in Brazil as jatobá, furnishes a high yield of viscous xyloglucan (45%) from its seeds. The crude polysaccharide (B1) was hydrolysed and the products, analysed as alditol acetates, were glucose, xylose, galactose and arabinose in the ratio 50:35:13:2. After further fractionation on a DEAE-cellulose column (chloride form), the main fraction (70% yield, B2) was obtained. The basic structure of the xyloglucan was determined as a cellulose-type (1 → 4)-linked β-d-glucan backbone partially substituted with side chains at 06 of -d-xylopyranose, some of which were themselves substituted at 02 by the units of β-d-galactopyranose. Treatment of the xyloglucan (B2) with commercial cellulase from Trichoderma sp. yielded six oligosaccharides. These oligosaccharides were isolated by preparative paper chromatography, and their structures were determined by gas-liquid chromatography-mass spectroscopy of the derived partially O-methylated alditol acetates. These results confirm the structure proposed for jatobá seed xyloglucan. 相似文献
94.
95.
Laminin and Neuropeptide Y Are Increased by Synapsin Transfection in Cultured NG108-15 Neuroblastoma/Glioma Hybrid Cells 总被引:2,自引:0,他引:2
† Gabriel Fried Hui Quan Han ‡Björn Meister ‡Tomas Hökfelt Paul Greengard 《Journal of neurochemistry》1995,64(6):2674-2680
Abstract: We have investigated the presence and expression of laminin and neuropeptide Y (NPY) in several NG108-15 cell lines transfected with synapsin Ib, IIa, or IIb. The content of laminin, a basal membrane glycoprotein that promotes adhesion and induces neurite outgrowth and neuronal differentiation, was increased in all transfected cell lines examined. In cells that were chemically differentiated with prostaglandin E1 plus 3-isobutyl-1-methylxanthine, laminin levels were increased even further. The content of NPY, suggested to be a neurotransmitter/neuromodulator in peripheral sympathetic neurons as well as in central neurons, was also increased in all transfected cell lines examined. Immunohistochemical analysis combined with confocal laser microscopy showed that NPY staining was granular and very often enriched in neuritic varicosities. The distribution and the staining pattern of NPY were consistent with storage of NPY in large dense-cored vesicles. The results indicate that, in differentiated neurons, the synapsins increase the levels of a neuropeptide transmitter stored in large dense-cored vesicles and of an extracellular matrix protein associated with neuronal maturation. 相似文献
96.
Swim Stress Increases the Potency of Glycine at the N-Methyl-d-Aspartate Receptor Complex 总被引:1,自引:0,他引:1
Gabriel Nowak †Anna Redmond †Mairead McNamara ‡ Ian A. Paul 《Journal of neurochemistry》1995,64(2):925-927
Abstract: We have previously demonstrated that chronic administration of antidepressants results in a reduction in the potency of glycine to displace 5,7-[3 H]dichlorokynurenic acid (5,7-[3 H]-DCKA) from the strychnine-insensitive glycine recognition site of the NMDA receptor complex. We now report that exposure of rats to the forced swim test results in a 56% increase in the potency of glycine to displace 5,7-[3 H]DCKA from frontal cortical homogenates. These data are consistent with the hypothesis that the forced swim test, a preclinical screen sensitive to acute administration of antidepressant drugs and NMDA receptor antagonists, also results in adaptation of the NMDA receptor complex. Moreover, these data lend further support to the hypothesis that glutamatergic pathways are involved in the neurobiological response to stress and, potentially, in the pathophysiology of depression. 相似文献
97.
K. A. Koehler M. K. Jain D. A. Gabriel H. -Y. C. Chang O. P. Malhotra 《Journal of Protein Chemistry》1995,14(7):537-548
The interaction of bovine prothrombin with Ca2+ and Mg2+ ions was investigated by following H+ release as a function of metal ion concentration at pH 6 and pH 7.4 at high and low ionic strength. Prothrombin Ca2+ and Mg2+ binding is characterized by high- and low-affinity sites. M2+ binding at these sites is associated with intramolecular conformational changes and also with intermolecular self-association. The pH dependence of H+ release by M2+ is bell shaped and consistent with controlling pKa values of 4.8 and 6.5. At pH 6 and low ionic strength, both Ca2+ and Mg2+ titrations following H+ release clearly show independent low- and high-affinity binding sites. Laser light scattering reveals that at pH 7.4 and low ionic strength, and at pH 6.0 and high ionic strength, the prothrombin molecular weight is between 73 and 98 kD. At pH 7.4 and high ionic strength, prothrombin is monomeric in the absence of metal ions, but appears to dimerize in the presence of M2+. At pH 6.0 and low ionic strength prothrombin exists as a dimer in the absence of metal ions and is tetrameric in the presence of Ca2+ and remains dimeric in the presence of Mg2+. These results and those for metal ion-dependent H+ release indicate that H+ release occurs concomitantly with association processes involving prothrombin.Abbreviations GLA
-carboxyglutamic acid; fragment 1. amino terminal residues 1–156 of bovine prothrombin
- MES
2-(N-morpholino) ethanesulfonic acid
- MOPS
3-(N-morpholino) propanesulfonic acid
- PS/PC
phosphatidylserine/phosphatidylcholine vesicles
-
ionic strength 相似文献
98.
Gabriel Guillet Marie-Ève Lavigne Bernard J. R. Philogène J. Thor Arnason 《Journal of Insect Behavior》1995,8(4):533-546
Two phototoxic plants of the Asteraceae family were studied in relation to species of phytophagous insects for which they are hosts:Argyrotaenia velutinana Wlk. feeding onChrysanthemum leucanthemum L. andChlorochlamys chloroleucaria (Guenée) colonizingRudbeckia hirta L. The toxicity of these two plants is related to the presence of acetylenes and thiophenes that induce a light-mediated production of deleterious singlet oxygen and other free radicals (phototoxicity). Results showed that females ofA. velutinana laid their eggs preferentially in the shade and the larvae adopted hiding behaviors, such as bending of ligulate corollas and silk spinning to build opaque shelters. By avoiding direct exposure to the sun, both behaviors may reduce phototoxicity associated with ingested plant materials. Furthermore, larvae ofC. chloroleucaria demonstrated a preference in the field for pollen, which constitutes a nonphototoxic tissue of their host plant. Experimental alterations of these specific behaviors induced important biological consequences for larvae of both insects such as mortality or reduction of larval growth rate. These results reinforce the idea that behavior may constitute an efficient adaptation to avoid phototoxicity. 相似文献
99.
Jacqueline Besson Monique Dussaillant Jean-Claude Marie William Rostene Gabriel Rosselin 《Peptides》1984,5(2):339-340
This paper describes the autoradiographic distribution of VIP binding sites in the rat central nervous system using monoiodinated 123I-labeled VIP. High densities of VIP binding sites are observed in the granular layer of the dorsal dentate gyrus of the hippocampus, the basolateral amygdaloid nucleus, the dorsolateral and median geniculate nuclei of the thalamus as well as in the ventral part of the hypothalamic dorsomedial nucleus. 相似文献
100.
Yaīr Reisner Gabriel Gachelin Philippe Dubois Jean-François Nicolas Nathan Sharon François Jacob 《Developmental biology》1977,61(1):20-27
Peanut agglutinin (PNA), a lectin specific for terminal d-galactosyl residues, was found to react with embryonal carcinoma cells, but not with their differentiated derivatives. Receptors for PNA were detectable at the surface of all cells of the quasinullipotent F9 line and on only 50% of the multipotent PCC3/A/1 line. The fraction of the PCC3/A/1 population which expresses the F9 antigen was found to be included in the subpopulation carrying the PNA receptors. PNA+ and PNA? subpopulations of PCC3/A/1 were separated by a PNA-mediated reversible agglutination of PNA+ cells with rabbit erythrocytes. These subpopulations were essentially F9+ and F9?, respectively. 相似文献