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  • 1
    ISSN: 1432-1793
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The genomic structure of two morphological forms of the pyurid ascidian Herdmania momus — H. momus forma curvata and H. momus forma grandis—are compared using a rapidly evolving highly repetitive element isolated from the genome of H. momus forma curvata. A 663 bp (base pair) Cla I satellite sequence is present only in the genome of H. momus forma curvata, and hence can be used as a form-specific marker. Low-stringency Southern blot analyses, using the Cla I satellite as a probe, revealed that the genomes of H. momus forma grandis and another pyurid ascidian, Pyura stolonifera, do not contain similar sequences to the H. momus forma curvata repetitive element. In addition to this genomic dissimilarity, there are a number of significant reproductive and developmental differences between the two H. momus forms, and interform fertilisation rates are significantly lower than intraform rates. The molecular, reproductive and developmental differences between H. momus forma curvata and H. momus forma grandis indicate the presence of strong barriers to gene flow.
    Materialart: Digitale Medien
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Cellular and molecular life sciences 52 (1996), S. 979-994 
    ISSN: 1420-9071
    Schlagwort(e): Apoptosis ; protein tyrosine kinase ; protein kinase C ; cell cycle ; PI3-kinase ; DNA-PK
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract The transmission of signals from the plasma membrane to the nucleus involves a number of different pathways all of which have in common protein modification. The modification is primarily in the form of phosphorylation which leads to the activation of a series of protein kinases. It is now evident that these pathways are common to stimuli that lead to mitogenic and apoptotic responses. Even the same stimuli under different physiological conditions can cause either cell proliferation or apoptosis. Activation of specific protein kinases can in some circumstances protect against cell death, while in others it protects the cell against apoptosis. Some of the pathways involved lead to activation of transcription factors and the subsequent induction of genes involved in the process of cell death or proliferation. In other cases, such as for the tumour suppressor gene product p53, activation may be initiated both at the level of gene expression or through pre-existing proteins. Yet in others, while the initial steps in the pathway are ill-defined, it is clear that downstream activation of a series of cysteine proteases is instrumental in pushing the cell towards apoptosis. In this report we review the involvement of protein kinases at several different levels in the control of cell behavior.
    Materialart: Digitale Medien
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Marine biology 98 (1988), S. 95-100 
    ISSN: 1432-1793
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract A procedure is described for the extraction of DNA and RNA from solitary and colonial ascidians obtained on the east coast of Australia. Modifications to more established procedures have been made to avoid nuclease digestion, binding to polyphenolic compounds and other less well characterized pigments that interfere with the use of nucleic acids for restriction-enzyme analysis and gene-cloning. Tissue is homogenized in liquid nitrogen to produce a powder which is washed three times in 0.25 M ammonium acetate, pH 5.0, to remove a variety of contaminants. This is followed by lysis and immediate extraction in a number of different phenol/CHCl3/isoamyl alcohol mixtures. Additional steps are similar to those described in previous methods. Extraction of RNA by this procedure precludes the necessity for addition of ribonuclease inhibitors.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    ISSN: 1432-1203
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Polymorphism of the human c-Ha-ras-1 gene has been analysed in DNA from 168 individuals using the enzymes MspI and HpaII. In all, 35 bladder cancer patients, 28 melanoma patients, 22 Wilms' tumour patients, 24 first-degree relatives of Wilms' tumour or melanoma patients and 59 unaffected controls were studied. A total of 13 different fragment sizes was detected, 4 “common” and 9 “unusual”. Of the latter, 4 were observed only in cancer patients or their first-degree relatives. The frequency of unusual alleles was significantly greater in bladder cancer patients and in the combined tumour group than in controls, thus providing support for the association of unique Ha-ras alleles and cancer. Some unaffected relatives of patients carried unusual alleles, and thus there is no absolute relationship between Ha-ras genotype and disease.
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    Springer
    Molecular biology reports 11 (1986), S. 143-147 
    ISSN: 1573-4978
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Micrococcal nuclease was used as a probe to study chromatin structure in control and ataxia-telangiectasia cells. The rate and extent of release of acid-soluble nucleotide was similar in both cell types. Production of mono- and oligonucleosomes by micrococcal nuclease as determined by gel electrophoresis also failed to reveal differences in chromatin structure between control and ataxia-telangiectasia cells. Radiation exposure did not significantly alter the kinetics of digestion. These results indicate that there are no gross alterations in chromatin structure in ataxia-telangiectasia cells.
    Materialart: Digitale Medien
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  • 6
    Digitale Medien
    Digitale Medien
    Springer
    Urological research 15 (1987), S. 341-344 
    ISSN: 1434-0879
    Schlagwort(e): Transferrin receptors ; Human bladder carcinoma
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The expression of transferrin receptors (TFR) by normal and neoplastic urothelial cells was studied in “control” patients and in patients with transitional cell carcinoma of the bladder. These tumours were graded independently and consisted of 19 grade I, 30 grade II and 19 grade III lesions. TFRs were identified using a monoclonal antibody specific for TFR (OKT9) in an immunofluorescent or avidin/biotin-immunoperoxidase technique on fresh frozen sections. TFRs were not detected on normal urothelium. However, positive staining was found to increase with increasing pathological grade and stage of the tumours, ranging from 31.6% of grade I to 78.9% of grade III tumours and 51.2% of pTa (mucosa only lesions) to 87.5% of pT2/pT2+ (muscle invasion±deeper) primary urothelial malignancies.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 7
    ISSN: 1434-0879
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Sections of formalin-fixed, paraffin-blocked tissue from 116 primary transitional cell carcinomas were stained immunohistochemically using a polyclonal antibody against the c-erbB-2 oncoprotein. Positive staining of cell membranes, known to correlate with gene amplification, was seen in 22 (19%) of the 116, with variable staining from tumour to tumour and within tumours themselves. Consistent with its mooted value as a prognosticator in bladder cancer, the c-erbB-2 oncoprotein was detected in 13 (of 40) grade III and 9 of the 26 muscle-invasive tumours examined compared to 1 (of 25) grade I and 6 (of 66) mucosa only (pTa) lesions. These results support further examination of c-erbB-2 expression in bladder cancer.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 8
    ISSN: 1434-0879
    Schlagwort(e): Immunohistology ; Non-seminomatous germ cell tumors
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Immunohistological techniques were used to characterise inflammatory cell infiltrates in mixed germ cell tumours. The distribution of these infiltrates was much more variable than in pure seminomas but could not be related accurately to any particular tumour type. There were approximately equal numbers of B and T cells in these areas and helper/inducer T cells were more common than suppressor/cytotoxic lymphocytes. Within these areas of inflammatory cells, the subtype composition was similar to that seen in pure seminomas.
    Materialart: Digitale Medien
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  • 9
    Digitale Medien
    Digitale Medien
    Springer
    Archives of virology 119 (1991), S. 13-23 
    ISSN: 1432-8798
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Integration of bovine leukaemia virus DNA was investigated at all stages of infection in cattle. We report here the detection of integrated proviral DNA in the majority of antibody positive animals without lymphocytosis. In all but one case virus was integrated at a number of different sites. Hybridization analysis failed to detect proviral sequences in animals shown to be BLV antibody-negative by the Agar Gel Immunodiffusion assay. The pattern of integration in leukocytes from animals with persistent lymphocytosis was similar to that in sero-positive animals without lymphocytosis in that multiple sites of integration were evident. As reported by others only one or a few sites of integration were detected in tumours from enzootic bovine leukosis animals. Tumours from different sites in individual animals were either monoclonal or oligoclonal.
    Materialart: Digitale Medien
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