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61.
Protein targeting into plant mitochondria was investigated by in vitro translocation experiments. The precursor of the mitochondrial F1-ATPase beta subunit from Nicotiana plumbaginifolia was synthesized in vitro, translocated to, processed, and assembled in purified Vicia faba mitochondria. Transport (but not binding) required a membrane potential and external nucleotides and was conserved among plant species. beta subunit precursors from the yeasts Saccharomyces cerevisiae and Schizosaccharomyces pombe were imported and correctly processed in plant mitochondria. This translocation used protease-sensitive components of the outer membrane. Conversely, the N. plumbaginifolia beta subunit precursor was efficiently translocated and cleaved in yeast mitochondria. However, a precursor for a chloroplast protein was not targeted to plant or yeast mitochondria. We conclude that the machinery for protein import into mitochondria is specific and conserved in plant and yeast organisms. These results are discussed in the context of a poly- or monophyletic origin of mitochondria. 相似文献
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Oxidative stress contributes to cancer pathologies and to apoptosis. Marine algae exhibit cytotoxic, antiproliferative and apoptotic effects; their metabolites have been used to treat many types of cancer. We investigated in culture extracts of Petalonia fascia, Jania longifurca and Halimeda tuna to determine their effects on mouse neuroblastoma cell line, NA2B. NA2B cells were treated with algae extracts, and the survival and proliferation of NA2B cells were assessed using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The effects of algae extracts on oxidative stress in NA2B cells also were investigated using nitric oxide synthase (NOS) immunocytochemistry and apoptosis was assessed using terminal deoxynucleotidyl transferase dUTP nick end labeling. We observed significant neurite inhibition with moderate damage by the neurotoxicity-screening test (NST) at IC50 dilutions of the extracts. MTT demonstrated that J. longifurca extracts were more toxic than P. fascia and H. tuna extracts. We found an increase of endothelial and inducible NOS immunostaining for oxidative stress and TUNEL analysis revealed increased apoptosis after application of extract. Our findings suggest that the algae we tested may have potential use for treatment of cancer. 相似文献
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Regulators of complement activity mediate inhibitory mechanisms through a common C3b‐binding mode
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Federico Forneris Jin Wu Xiaoguang Xue Daniel Ricklin Zhuoer Lin Georgia Sfyroera Apostolia Tzekou Elena Volokhina Joke CM Granneman Richard Hauhart Paula Bertram M Kathryn Liszewski John P Atkinson John D Lambris Piet Gros 《The EMBO journal》2016,35(10):1133-1149
Regulators of complement activation (RCA) inhibit complement‐induced immune responses on healthy host tissues. We present crystal structures of human RCA (MCP, DAF, and CR1) and a smallpox virus homolog (SPICE) bound to complement component C3b. Our structural data reveal that up to four consecutive homologous CCP domains (i–iv), responsible for inhibition, bind in the same orientation and extended arrangement at a shared binding platform on C3b. Large sequence variations in CCP domains explain the diverse C3b‐binding patterns, with limited or no contribution of some individual domains, while all regulators show extensive contacts with C3b for the domains at the third site. A variation of ~100° rotation around the longitudinal axis is observed for domains binding at the fourth site on C3b, without affecting the overall binding mode. The data suggest a common evolutionary origin for both inhibitory mechanisms, called decay acceleration and cofactor activity, with variable C3b binding through domains at sites ii, iii, and iv, and provide a framework for understanding RCA disease‐related mutations and immune evasion. 相似文献
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CM Ward AP Wilkinson S Bramham HA Lee HW-S Chan GW Butcher A Hutchings MRA Morgan 《Mycotoxin Research》1990,6(2):73-83
From a single aflatoxin B1 oxime — bovine serum albumin conjugate, polyclonal and monoclonal antibody preparations were produced. The four rabbit polyclonal antisera were specific for aflatoxin Bi in a microtitration plate enzyme — linked immunosorbent assay. The monoclonal antibodies showed a wide range of differing specificities, recognizing, for example, aflatoxins B1, B2, G1 and G2; B1 and B2; B1 and G1; and G1 alone. No antibody preparations reacted with aflatoxin M1. The significance of these results to the strategy of anti-aflatoxin antibody production for use in quantitative enzyme immunoassays is discussed. 相似文献
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Morphology of cultured guinea-pig cerebellum 总被引:1,自引:0,他引:1
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Abstract: The distribution of pyruvate kinase (ATP pyruvate phosphotransferase, EC 2.7.1.40) in the nervous system has been studied by both immunofluorescence and a histochemical procedure using nitro blue tetrazolium. The localization in various parts of rat central nervous system in situ , cerebellar and cerebral cortex, was compared to that found in vitro in cultures of cerebellum, spinal ganglia, cerebral astrocytes, and skin fibroblasts. (1) Pyruvate kinase was found predominantly in the cytoplasm of neuronal cell bodies. (2) Large neurons were better visualized than small ones. (3) No glial localization was clearly demonstrated in situ , although this does not rule out the presence of some M1 pyruvate kinase. (4) Regions expected to be rich in nerve terminals, such as the cerebellar glomeruli or the cerebellar molecular layer, showed intense staining even when the cell bodies themselves were negative. This was expected, owing to the previous demonstration of the presence of M1 pyruvate kinase in nerve ending by subcellular fractionation methods. (5) The localization was similar in situ and in tissue culture, except that nerve processes were better seen in the latter and astrocytes were sometimes stained in vitro. (6) Variation in intensity of staining was observed in similar cell types in the same section or in the same culture. This could represent different metabolic or functional or maturational states. 相似文献