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981.
G. Luca Colucci-D''Amato Angela Tino Roberto Pernas-Alonso Jarlath M. H. ffrench-Mullen Umberto di Porzio 《Experimental cell research》1999,252(2):383-391
A mes-c-myc A1 (A1) cell line was generated by retroviral infection of cultured embryonic mesencephalic cells and selected by neomycin resistance. A1 cells cease to divide and undergo morphological differentiation after serum withdrawal or addition of c-AMP. Proliferating or morphologically differentiated A1 cells are all positive for vimentin and nestin, a marker of neural precursor, and show neuronal markers such as microtubule-associated protein 1, neuron-specific enolase and peripherin, and the glial marker glial fibrillary acidic protein. Neuronal and glial markers coexist in single cells. Furthermore, A1 cells show presence of glutamic acid decarboxylase 67 mRNA and its embryonic form EP10 and accumulate the neurotransmitter GABA. Electrophysiological studies demonstrate that morphologically differentiated A1 cells display voltage-gated sodium and potassium channels in response to depolarizing stimuli. A1 cells thus represent a novel, bipotent neural cell line useful for studying CNS differentiation and plasticity, as well as the molecular mechanisms underlying development of GABAergic neurotransmission. 相似文献
982.
I. L. Bogdankevich D. M. Grishin A. V. Gunin I. E. Ivanov S. D. Korovin O. T. Loza G. A. Mesyats D. A. Pavlov V. V. Rostov P. S. Strelkov D. K. Ul’yanov 《Plasma Physics Reports》2008,34(10):855-859
A repetitively rated microwave oscillator whose frequency can be varied electronically from pulse to pulse in a predetermined manner is created for the first time. The microwave oscillator has a power on the order of 108 W and is based on the Cherenkov interaction of a high-current relativistic electron beam with a plasma preformed before each pulse. Electronic control over the plasma properties allows one to arbitrarily vary the microwave frequency from pulse to pulse at a pulse repetition rate of up to 50 Hz. 相似文献
983.
Kawano T Muto S Adachi M Hosoya H Lapeyrie F 《Bioscience, biotechnology, and biochemistry》2002,66(3):646-650
We obtained spectroscopic evidence in support of salicylate-dependent inactivation of horseradish peroxidase-C. Addition of salicylate to the enzyme arrested at a temporal inactive state (Compound III) in the presence of H2O2, resulted in rapid and irreversible inactivation of the enzyme yielding verdohemoproteins (P-670). Multiple roles for salicylate in peroxidase-catalyzed reactions are discussed. 相似文献
984.
Salts at high concentrations may cause oxidative damage to plant cells since many studies indicated the involvement of reactive oxygen species in salt-stress response. Recently, we have demonstrated that treatment of tobacco ( Nicotiana tabacum ) cell suspension culture with various salts result in an immediate burst of superoxide production via activation of NADPH oxidase by ions of alkali metals (Li+ , Na+ , K+ ), alkali earth metals (Mg2+ , Ca2+ ) or lanthanides (La3+ , Gd3+ ). In this study, we tested the effect of extracellular supplementation of Zn2+ and Mn2+ on the cation-induced oxidative burst in tobacco cell suspension culture, measured with a superoxide-specific Cypridina luciferin-derived chemiluminescent reagent. Extracellular supplementation of Zn2+ and Mn2+ inhibited the generation of superoxide in response to addition of salts. Although both Zn2+ and Mn2+ inhibited the salt-induced generation of superoxide, the modes of inhibition by those ions seemed to be different since Mn2+ simply inhibited total production of superoxide while Zn2+ inhibited the early phase of superoxide production and induced the slow release of superoxide. Roles of Mn2+ and Zn2+ in protection of plant cells from salt stress, as an effective superoxide scavenger and an effective inhibitor of plasma membrane-bound NADPH oxidase, respectively, are discussed. 相似文献
985.
Richard Reynolds Mary Dawson Dimitrios Papadopoulos Annabella Polito Isabelle Cenci di Bello Danielle Pham-Dinh Joel Levine 《Brain Cell Biology》2002,31(6-7):523-536
Remyelination of primary demyelinated lesions is a common feature of experimental models of multiple sclerosis (MS) and is also suggested to be the normal response to demyelination during the early stages of MS itself. Many lines of evidence have shown that remyelination is preceded by the division of endogenous oligodendrocyte precursor cells (OPCs) in the lesion and its borders. It is suggested that this rapid response of OPCs to repopulate the lesion site and their subsequent differentiation into new oligodendrocytes is the key to the rapid remyelination. Antibodies to the NG2 chondroitin sulphate proteoglycan have proved exceedingly useful in following and quantitating the response of endogenous OPCs to demyelination. Here we review the literature on the response of NG2-expressing OPCs to demyelination and provide some new evidence on their response to the chronic inflammatory demyelinating environment seen in recombinant myelin oligodendrocyte glycoprotein (MOG) induced experimental allergic encephalomyelitis (EAE) in the DA rat. NG2-expressing OPCs responded to the inflammatory demyelination in this model by becoming reactive and increasing in number in a very focal manner. Evidence of NG2+OPCs in lesioned areas beginning to express the oligodendrocyte marker CNP was also seen. The response of OPCs appeared to occur following successive relapses but did not always lead to remyelination, with areas of chronic demyelination observed in the spinal cord. The presence of OPCs in the adult human CNS is clearly of vital importance for repair in multiple sclerosis (MS). As in rat tissue, the antibody labels an evenly distributed cell population present in both white and grey matter, distinct from HLA-DR+microglia. NG2+cells are sparsely distributed in the centre of chronic MS lesions. These cells apparently survive demyelination and exhibit a multi-processed or bipolar morphology in the very hypocellular environment of the lesion. 相似文献
986.
Developing seeds of Arabidopsis store different minerals in two types of vacuoles and in the endoplasmic reticulum 总被引:12,自引:0,他引:12 下载免费PDF全文
Mineral-accumulating compartments in developing seeds of Arabidopsis were studied using high-pressure-frozen/freeze-substituted samples. Developing seeds store minerals in three locations: in the protein storage vacuoles of the embryo, and transiently in the endoplasmic reticulum (ER) and vacuolar compartments of the chalazal endosperm. Energy dispersive x-ray spectroscopy and enzyme treatments suggest that the minerals are stored as phytic acid (myo-inositol-1,2,3,4,5,6-hexakisphosphate) salts in all three compartments, although they differ in cation composition. Whereas embryo globoids contain Mg, K, and Ca as cations, the chalazal ER deposits show high levels of Mn, and the chalazal vacuolar deposits show high levels of Zn. The appearance of the first Zn-phytate crystals coincides with the formation of network-like extensions of the chalazal vacuoles. The core of these networks consists of a branched network of tubular ER membranes, which are separated from the delineating tonoplast membranes by a layer of cytosolic material. Degradation of the networks starts with the loss of the cytosol and is followed by the retraction of the ER, generating a network of collapsed tonoplast membranes that are resorbed. Studies of fertilized fis2 seeds, which hyperaccumulate Zn-phytate crystals in the chalazal vacuolar compartments, suggest that only the intact network is active in mineral sequestration. Mineral determination analysis and structural observations showed that Zn and Mn are mobilized from the endosperm to the embryo at different developmental stages. Thus, Zn appears to be removed from the endosperm at the late globular stage, and Mn stores appear to be removed at the late bent-cotyledon stage of embryo development. The disappearance of the Mn-phytate from the endosperm coincides with the accumulation of two major Mn binding proteins in the embryo, the 33-kD protein from the oxygen-evolving complex of photosystem II and the Mn superoxide dismutase. The possible functions of transient heavy metal storage in the chalazal endosperm are discussed. A model showing how phytic acid, a potentially cytotoxic molecule, is transported from its site of synthesis, the ER, to the different mineral storage sites is presented. 相似文献
987.
Nielen S Vidigal BS Leal-Bertioli SC Ratnaparkhe M Paterson AH Garsmeur O D'Hont A Guimarães PM Bertioli DJ 《Molecular genetics and genomics : MGG》2012,287(1):21-38
Cultivated peanut is an allotetraploid with an AB-genome. In order to learn more of the genomic structure of peanut, we characterized
and studied the evolution of a retrotransposon originally isolated from a resistance gene analog (RGA)-containing bacterial
artificial chromosome (BAC) clone. It is a moderate copy number Ty1-copia retrotransposon from the Bianca lineage and we named it Matita. Fluorescent in situ hybridization (FISH) experiments showed that Matita is mainly located on the distal regions of chromosome arms and is of approximately equal frequency on both A- and B-chromosomes.
Its chromosome-specific hybridization pattern facilitates the identification of individual chromosomes, a useful cytogenetic
tool considering that chromosomes in peanut are mostly metacentric and of similar size. Phylogenetic analysis of Matita elements, molecular dating of transposition events, and an estimation of the evolutionary divergence of the most probable
A- and B-donor species suggest that Matita underwent its last major burst of transposition activity at around the same time of the A- and B-genome divergence about
3.5 million years ago. By probing BAC libraries with overgos probes for Matita, resistance gene analogues, and single- or low-copy genes, it was demonstrated that Matita is not randomly distributed in the genome but exhibits a significant tendency of being more abundant near resistance gene
homologues than near single-copy genes. The described work is a further step towards broadening the knowledge on genomic and
chromosomal structure of peanut and on its evolution. 相似文献
988.
989.
Jacob G. Jansen Piya Temviriyanukul Niek Wit Frédéric Delbos Claude-Agnès Reynaud Heinz Jacobs Niels de Wind 《Nucleic acids research》2014,42(17):11071-11082
Short-wave ultraviolet light induces both mildly helix-distorting cyclobutane pyrimidine dimers (CPDs) and severely distorting (6–4) pyrimidine pyrimidone photoproducts ((6–4)PPs). The only DNA polymerase (Pol) that is known to replicate efficiently across CPDs is Polη, a member of the Y family of translesion synthesis (TLS) DNA polymerases. Phenotypes of Polη deficiency are transient, suggesting redundancy with other DNA damage tolerance pathways. Here we performed a comprehensive analysis of the temporal requirements of Y-family Pols ι and κ as backups for Polη in (i) bypassing genomic CPD and (6–4)PP lesions in vivo, (ii) suppressing DNA damage signaling, (iii) maintaining cell cycle progression and (iv) promoting cell survival, by using mouse embryonic fibroblast lines with single and combined disruptions in these Pols. The contribution of Polι is restricted to TLS at a subset of the photolesions. Polκ plays a dominant role in rescuing stalled replication forks in Polη-deficient mouse embryonic fibroblasts, both at CPDs and (6–4)PPs. This dampens DNA damage signaling and cell cycle arrest, and results in increased survival. The role of relatively error-prone Pols ι and κ as backups for Polη contributes to the understanding of the mutator phenotype of xeroderma pigmentosum variant, a syndrome caused by Polη defects. 相似文献
990.
Imran Khan Emanuel Maldonado Vítor Vasconcelos Stephen J O’Brien Warren E Johnson Agostinho Antunes 《BMC genomics》2014,15(1)