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  • Electronic Resource  (6)
  • Life and Medical Sciences  (6)
  • 1
    Electronic Resource
    Electronic Resource
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 59 (1995), S. 177-185 
    ISSN: 0730-2312
    Keywords: citric acid ; cell nuclei ; extraction of proteins ; nuclear membranes ; RNA helicase A ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The treatment of isolated cell nuclei with citric acid was described as a method for separating inner and outer nuclear membrane. Using cell nuclei from bovine cerebral cortex, we can show that citric acid does not cause a separation of the two nuclear membranes, but extracts a specific set of proteins from the nuclei. The extraction of proteins is not just an effect of damaging the nuclear membrane or destructing the cytoskeleton, but rather a specific effect of citric acid treatment. One of the extracted proteins, chosen as a marker for the putative outer nuclear membrane fraction, has an apparent molecular weight of 145 kDa and is located in the nucleoplasm as shown by immunofluorescence microscopy. By sequencing tryptic peptides it was identified as RNA helicase A, an abundant nuclear protein assumed to participate in the processing of mRNA. © 1995 Wiley-Liss, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0730-2312
    Keywords: polyamines ; erythrocyte ; biomarker ; reproducibility ; plasma micronutrients ; antioxidant ; intervention ; cancer prevention ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Erythrocyte polyamine measurements have been previously investigated as candidate biomarkers for hyperproliferation and recently as a potential intermediate endpoint in clinical chemoprevention trials with difluoromethylornithine, an inhibitor of polyamine biosynthesis. This study was performed to determine the reproducibility of erythrocyte polyamine measurements and their possible correlation with plasma micronutrients in seven healthy adults in an antioxidant vitamin intervention study. As part of this cross-over intervention study, three subjects took β-carotene (31.4 mg/day) plus D-α-tocopherol acetate (720 IU/day) supplements during the first 3 months and four subjects took the supplements during the second 3 months. Heparinized blood samples were collected at baseline and every month over total 6 months for simultaneous determination of erythrocyte polyamines and plasma micronutrients by the high-performance liquid chromatographic method. For all the measures of erythrocyte polyamines the intraindividual variation was smaller than that between subjects, and three or four measurements required to accurately characterize long-term erythrocyte polyamines for an individual. The intra-class correlations were moderately high for all erythrocyte polyamine measurements, indicating a good reproducibility for intra-individual erythrocyte polyamine measurements. Based on monthly values, significant inverse correlations were found between erythrocyte spermidine and the plasma levels of retinol (r = -0.50) and lutein (r = -0.52). There were also significant inverse associations between erythrocyte spermine and plasma levels of α-tocopherol (r = -0.29), lutein (r = -0.44), lycopene (r = -0.29), β-cryptoxanthin (r = -0.30), and total carotenoids (r = -0.29). The effects of supplementation upon the associations between erythrocyte polyamines and plasma nutrient levels were additionally addressed. The results indicate an acceptable longitudinal reproducibility of erythrocyte polyamine measurements, support the hypothesis that erythrocyte polyamine measurements may be correlated with plasma levels of certain nutrients, and suggest a further biomarker application in cancer prevention trials involving dietary modifications or specific relevant micronutrients. © 1996 Wiley-Liss, Inc.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 225 (1995), S. 51-60 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The humpback whale (Megaptera novaeangliae) is reported to use its elongate pectoral flippers during swimming maneuvers. The morphology of the flipper from a 9.02-m whale was evaluated with regard to this hydrodynamic function. The flipper had a wing-like, high aspect ratio plan-form. Rounded tubercles were regularly interspersed along the flipper's leading edge. The flipper was cut into 71 2.5-cm cross-sections and photographed. Except for sections near the distal tip, flipper sections were symmetrical with no camber. Flipper sections had a blunt, rounded leading edge and a highly tapered trailing edge. Placement of the maximum thickness placement for each cross-section varied from 49% of chord at the tip to 19% at mid-span. Section thickness ratio averaged 0.23 with a range of 0.20-0.28. The humpback whale flipper had a cross-sectional design typical of manufactured aerodynamic foils for lift generation. The morphology and placement of leading edge tubercles sugges that they function as enhanced lift devices to control flow over the flipper and maintain lift at high angles of attack. The morphology of the humpback whale flipper suggests that it is adapted for high maneuverability associated with the whale's unique feeding behavior. © 1995 Wiley-Liss, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 0192-253X
    Keywords: transformation ; gene structure ; cAMP ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The cyclic nucleotide phosphodiesterase (phosphodiesterase) of Dictyostelium discoideum plays an essential role in development by hydrolyzing the cAMP used as a chemoattractant by aggregating cells. We have studied the biochemistry of the phosphodiesterase and a functionally related protein, the phosphodiesterase inhibitor protein, and have cloned the cognate genes. A 1.8-kb and a 2.2-kb mRNA are transcribed from the singlephosphodiesterase gene. The 2.2-kb mRNA comprises the majority of the phosphodiesterase mRNA found in differentiating cells and is transcribed only during development from a promoter at least 2.5 kb upstream of the translational start site. The 1.8-kb phosphodiesterase mRNA is detected at all stages of growth and development, is present at lower levels than the developmentally induced mRNA, and is transcribed from a site proximal to the protein-coding region. The phosphodiesterase gene contains a minimum of three exons, and a 2.3-kb intron, the longest yet reported for this organism. We have shown that the pds A. gene and fourfgd genes affect, the accumulation of the phosphodiesterase mRNAs, and we believe that these loci represent a significant portion of the genes regulating expression of the phosphodiesterase. The phosphodiesterase gene was introduced into cells by transformation and used as a tool to explore the effects of cAMP on the terminal stages of development. In cells expressing high levels of phosphodiesterase activity, final morphogenesis cannot be completed, and differentiated spore and stalk cells do not form. We interpret these results to support the hypothesis that cAMP plays an essential role in organizing cell movements in late development as well as in controlling the aggregation of cells in the initial phase of the developmental program.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 0192-253X
    Keywords: cAMP ; chemotaxis ; transformation ; CAT constructs ; gene regulation ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The genes coding for the cyclic nucleotide phosphodiesterase (PD) and the PD inhibitory glycoprotein (PDI) have been cloned and characterized. The PDI gene was isolated as a 1.6 kb genomic fragment, which included the coding sequence containing two small introns and 510 nucleotides of non-translated 5′ sequence. From the deduced amino acid sequence we predict a protein with a molecular weight (MW) of 26,000 that, in agreement with previous data, contains 15% cysteine residues. Genomic Southern blot analysis indicates that only one gene encodes the inhibitor. Northern blot analysis shows a single transcript of 0.95 kb. The PDI gene is expressed early in development with little transcript remaining following aggregation. The appearance of PDI mRNA is prevented by the presence of cAMP, but when cAMP is removed the transcript appears within 30 minutes. When cAMP is applied to cells expressing PDI the transcript disappears with a half-life of less than 30 minutes. The PD gene of D. discoideum is transcribed into three mRNAs: a 1.9 kb mRNA specific for growth, a 2.4 kb mRNA specific for aggregation, and a 2.2 kb mRNA specific for late development. The 2.2 kb mRNA is also specific for prestalk cells, and is induced by differentiation-inducing factor. All three mRNAs contain the same coding sequence, and differ only in their 5′ non-coding sequences. Each mRNA is transcribed from a different promoter, and by using the chloramphenicol acyltransferase gene as a reporter, we have shown that each promoter displays the same regulation as its cognate mRNA. Transformation of wild-type strains with the PD gene causes PD overexpression which accelerates aggregation and blocks subsequent cell differentiation and pattern formation.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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