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  • Life and Medical Sciences  (3)
  • Particle bombardment  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Molecular genetics and genomics 250 (1996), S. 750-760 
    ISSN: 1617-4623
    Keywords: Key words lys3a ; CpG island ; Transient expression ; Particle bombardment ; Immunocytochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  B- and C-hordein gene transcription is severely reduced in the endosperm of the regulatory barley mutant lys3a, and this is correlated with persistent hypermethylation of the promoters. In contrast, D-hordein is expressed at normal levels in the mutant. To confirm the connection between methylation and transcriptional activity, a genomic D-hordein clone was isolated and sequenced. The nucleotide composition of the promoter region revealed a CpG island and methylation analysis, using bisulphite treatment of genomic DNA, confirmed that the D-hordein promoter is unmethylated in endosperm and leaf tissue. Immunocytochemical studies localized D-hordein to the reticular component of protein bodies in both the wild-type Bomi and lys3a. Transient expression of GUS reporter gene constructs in barley endosperm, following transfection by particle bombardment revealed the D-hordein promoter to be 3–5 fold more active than B- or C-hordein promoters. Comparison of transient expression in Bomi and lys3a endosperm demonstrated that the activities of the unmethylated D-hordein and the Hor1-14 C-hordein promoters were equivalent, while the activities in the mutant of the Hor1-17 C-hordein and the Hor2-4 B-hordein promoters were reduced two- and tenfold, respectively. Methylation of plasmids in vitro prior to expression severely inhibited B- and D-hordein promoter activities. Based on these observations two categories of promoters for endosperm-specific expression of storage proteins are recognized and a model involving methylation and modulation of chromatin structure in the regulation by the Lys3 gene is presented.
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  • 2
    ISSN: 1617-4623
    Keywords: lys3a ; CpG island ; Transient expression ; Particle bombardment ; Immunocytochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract B- and C-hordein gene transcription is severely reduced in the endosperm of the regulatory barley mutantlys3a, and this is correlated with persistent hypermethylation of the promoters. In contrast, D-hordein is expressed at normal levels in the mutant. To confirm the connection between methylation and transcriptional activity, a genomic D-hordein clone was isolated and sequenced. The nucleotide composition of the promoter region revealed a CpG island and methylation analysis, using bisulphite treatment of genomic DNA, confirmed that the D-hordein promoter is unmethylated in endosperm and leaf tissue. Immunocytochemical studies localized D-hordein to the reticular component of protein bodies in both the wild-type Bomi andlys3a. Transient expression ofGUS reporter gene constructs in barley endosperm, following transfection by particle bombardment revealed the D-hordein promoter to be 3–5 fold more active than B-or C-hordein promoters. Comparison of transient expression in Bomi andlys3a endosperm demonstrated that the activities of the unmethylated D-hordein and theHor1-14 C-hordein promoters were equivalent, while the activities in the mutant of theHor1-17 C-hordein and theHor2-4 B-hordein promoters were reduced two- and tenfold, respectively. Methylation of plasmids in vitro prior to expression severely inhibited B- and D-hordein promoter activities. Based on these observations two categories of promoters for endosperm-specific expression of storage proteins are recognized and a model involving methylation and modulation of chromatin structure in the regulation by theLys3 gene is presented.
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  • 3
    Electronic Resource
    Electronic Resource
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 20 (1982), S. 163-176 
    ISSN: 0730-2312
    Keywords: epidermal growth factor ; asialoglycoprotein receptor ; ricin ; diphtheria toxin ; toxic conjugates ; hybrid toxins ; chimeric toxins ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: We have constructed hybrid proteins in which the toxic A chains of ricin or diptheria toxin have been linked to either asialofetuin, fetuin, or epidermal growth factor (EGF). Both ASF-RTA and ASF-DTA are potent toxins on cultured rat hepatocytes, cells that display the asialoglycoprotein receptor. Toxicity of these two compounds is restricted to hepatocytes and can be blocked by asialoglycoproteins but not the native glycoproteins or asialoagalactoglycoprotein derivatives, indicating that the toxicity of the conjugates is mediated by the hepatic asialoglycoprotein receptor. The EGF-RTA conjugate is an extremely potent toxin on cells that can bind the hormone, but is only poorly effective on cells that are unable to bind EGF. The EGF-DTA conjugate, in contrast, is unable to kill 3T3 cells and is at least two orders of magnitude less effective than EGF-RTA on A431 cells, a cell line with 1-2 × 106 EGF receptors per cell. However, when EGF-RTA and EGF-DTA were tested on primary liver hepatocyte cultures, which were susceptible to both ASF-RTA and ASF-DTA, both EGF conjugates were potent toxins. Sensitivity of the hepatocyte cultures to ricin toxicity increases slightly during a 52-hr culture period. In contrast, sensitivity to EGF-RTA and ASF-RTA decline dramatically during this period. Receptors for both ligands remain plentiful on the cell surface during this time.
    Additional Material: 6 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 131 (1987), S. 29-35 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The compensatory growth of the kidney which is induced by unilateral ne-phrectomy is a highly regulated process resulting principally in hypertrophy of the remaining kidney. The events which regulate this process are unknown. We have examined the levels of transcripts for the proto-oncogenes, myc, H-ras, K-ras, and fos, and the cellular genes, H4 histone, ornithine aminotrans-ferase, and gamma-glutamyl transpeptidase, following unilateral nephrec-tomy in the rat. The pattern of expression of c-myc, c-H-ras, and c-K-ras during compensatory growth of the kidney differs from the pattern of expression of these proto-oncogenes during liver regeneration, in which, unlike the kidney, hyperplasia rather than hypertrophy predominates. The lack of change in the abundance of these proto-oncogene transcripts following unilateral nephrec-tomy suggests a primary relationship between the expression of these proto-oncogenes and DNA synthesis and indicates there may be separate signals for cell growth, one to double cell size and one to replicate DNA. Increased mRNA transcripts for the enzymes ornithine aminotransferase and gamma-glutamyl transpeptidase were induced in the contralateral kidney after ne-phrectomy. The time course of expression for these two enzymes differs. The early expression of the gamma-glutamyl transpeptidase gene may indicate an involvement of this glutathione-metabolizing enzyme during renal compensatory growth, while the function of the delayed increase in ornithine amino-transferase transcripts in the remaining kidney is not apparent.
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  • 5
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Vinculin is a major cytoskeletal component in striated muscle, where it has been reported to form a rib-like structure between the cell membrane and the Z-disk termed a costamere. This arrangement of vinculin has been purported to be involved in the alignment of the myofibrils. However, the three-dimensional arrangement of vinculin in relation to the Z-disk of the myofibril was not known. In the present study, we examined the distribution of vinculin in striated muscle with monospecific antibodies using immunofluorescence and laser scanning confocal microscopy. Isolated cardiac and skeletal muscle cells from a variety of species, tissue sections, and neonatal myocytes with developing myofibrils were examined. Optical sectioning in the X-Y and X-Z planes demonstrated that vinculin immunoreactivity was heaviest at the periphery of the cell; however, the immunoreactivity was also distributed within the Z-disk although at a relatively reduced level. This distribution is potentially significant in understanding the physiological significance of vinculin in striated muscle function and in myofi-brillogenesis.
    Additional Material: 10 Ill.
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