The cdc25+gene of fission yeast encodes a phosphotyrosine phosphatase that dephosphorylates tyrosine-15 of p34cdc2and thereby activates p34cdc2/cyclin to bring about entry into M phase. We have ...recently cloned a human homolog, CDC25, which rescues the M-phase initiation defect of yeast cdc25 temperature-sensitive mutants. Antibodies raised against the CDC25 gene product specifically recognize human proteins of ≈55 and ≈52 kDa. Microinjection of affinity-purified anti-CDC25 antibodies into HeLa cells inhibits entry into mitosis. These observations suggest that the CDC25 gene products are essential for the initiation of mitosis in human cells, similar to their homologs in fission yeast and Drosophila. CDC25 gene products, like p34CDC2, are localized primarily in the nucleus during interphase, suggesting that activation of p34CDC2/cyclin by p52/p55CDC25occurs within the nucleus.
Proteomic studies have the potential to comprehensively define the composition of organelles but are limited by the organellar cross-contamination that arises during subcellular fractionation. ...Comparative proteomics of organellar subfractions can mitigate these problems, as demonstrated by a recent study involving the nuclear envelope.
We describe a procedure for the selection of alcohol dehyrogenase negative mutants in Drosophila. The method consists of exposing eggs and larvae to low concentrations of 1-pentyne-3-ol dissolved in ...the culture medium. Only those flies with greatly reduced levels of alcohol dehydrogenase activity survive. In addition, genotypically negative flies die if their mothers are alcohol dehydrogenase positive. Using this procedure and formaldehyde to generate mutants, we were able to detect seven alcohol dehydrogenase negative mutants out of 350,000 individuals subjected to selection. At least five of the mutants contain small deletions that include the alcohol dehydrogenase locus.
Objective. To elucidate the humoral immune response in patients with chronic fatigue syndrome (CFS), by identification and characterization of autoantibodies.
Methods. Initial immunofluorescence ...histochemistry studies of sera using human HEp‐2 cell substrate were followed by antibody class subtyping and colocalization studies with reference antibodies. Association of CFS autoantigens with insoluble cellular components was determined by in situ extraction of soluble components and subsequent immunofluorescence histochemistry studies on the extracted cell substrate.
Results. Of 60 CFS patients, 41 (68%) were positive for antinuclear antibodies. Localization of nuclear staining was found at the nuclear envelope (52%), in reticulated speckles (25%), in nucleoli (13%), and in dense fine speckles (5%). Twenty‐eight CFS sera (47%) also had antibodies to cytoplasmic antigens. The major cytoplasmic staining pattern was of the intermediate filament type (35%). The observed nuclear envelope pattern of staining co‐localized with lamina‐associated polypeptide 2 (an integral nuclear membrane protein), the reticulated speckle pattern co‐localized with nonsmall nuclear RNP splicing factor SC‐35, and the intermediate filament pattern co‐localized with vimentin. The intermediate filament antigen was shown to be vimentin in immunoblotting experiments using recombinant human vimentin, and one of the nuclear envelope antigens was shown previously to be lamin B1. Fifty of the 60 CFS patients (83%) had antibodies to one or another of these antigens, all of which are relatively insoluble cellular antigens, whereas a control group of patients without chronic fatigue had a significantly lower frequency of such antibodies (17%).
Conclusion. The high frequency of autoantibodies to insoluble cellular antigens in CFS represents a unique feature which might help to distinguish CFS from other rheumatic autoimmune diseases.
We have purified two major polypeptides of 54 and 56 kd from bovine erythrocytes that specifically bind the nuclear location sequence (NLS) of the SV40 large T antigen. When added to a permeabilized ...cell system for nuclear import, the purified proteins increase by 2- to 3-fold the nuclear accumulation of a fluorescent protein containing the large T antigen NLS. The import stimulation is saturable and dependent upon the presence of cytosol. Nuclear protein accumulation in vitro is sensitive to inactivation by N-ethylmaleimide (NEM). NEM inactivation can be overcome by addition of the purified NLS-binding proteins to the import system. NEM treatment of the purified proteins abolishes their ability to stimulate import but does not affect NLS binding. Our results indicate that the NLS-binding proteins are NEM-sensitive receptors for nuclear import. At least one other NEM-sensitive cytosolic activity and an NEM-insensitive cytosolic activity are also necessary for protein import in vitro.
Several sites from around the world are being used operationally and are suitable for vicarious calibration of space-borne imaging platforms. However, due to the proximity of these sites (e.g., Libya ...4), a rigorous characterization of the landscape is not feasible, limiting their utility for sensor intercalibration efforts. Due to its accessibility and similarities to Libya 4, the Algodones Sand Dunes System in California, USA, was identified as a potentially attractive intercalibration site for space-borne, reflective instruments such as Landsat. In March 2015, a 4-day field campaign was conducted to develop an initial characterization of Algodones with a primary goal of assessing its intercalibration potential. Five organizations from the US and Canada collaborated to collect both active and passive airborne image data, spatial and temporal measurements of spectral bidirectional reflectance distribution function, and in-situ sand samples from several locations across the Algodones system. The collection activities conducted to support the campaign goal is summarized, including a summary of all instrumentation used, the data collected, and the experiments performed in an effort to characterize the Algodones site. (C) The Authors.
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