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  • Life and Medical Sciences  (11)
  • Industrial Chemistry  (6)
  • Archaebacteria  (4)
  • 1
    ISSN: 1432-1432
    Keywords: Ribosomal proteins ; Elongation factors ; Nucleotide sequence ; Archaebacteria ; Phylogeny
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary By a chromosome walking strategy the DNA region fromMethanococcus vannielii flanking the genes for protein synthesis elongation factor (EF) 1α and EF-2 was cloned and sequenced. A gene organization of 5′-β′-open reading frame (ORF) 1-ORF2-S12-S7-EF-2-EF-1α-S10-ORF3-ORF4-3′ was found where β′, S12, S7, S10, EF-2, and EF-1α represent gene products with sequences similar to the β′ subunit of RNA polymerase, ribosomal proteins S12, S7, and S10, and EF-G and EF-Tu fromEscherichia coli, respectively. ORF1-4 represent gene products with no known eubacterial counterparts. Northern blot analysis of transcripts and nuclease S1 mapping showed that transcription initiates between β′ and ORF1 and terminates at the 3′ side of the S10 gene and that the genes from ORF1 to S10 are contranscribed. Apart from the presence of two additional ORFs, ORF1 and ORF2, and of the gene for S10, this organization is identical to that of the eubacterial “streptomycin operon.” ORF1 displays sequence similarity to rat liver ribosomal protein L30 and may represent one of the “additional” ribosomal proteins ofMethanococcus. The sequenced part of the β′ gene and the EF-2 and EF-1α gene products fromMethanococcus, are more similar to their eukaryotic than to their eubacterial counterparts. It appears, therefore, that the genetic organization of the translational components resembles the situation in eubacteria, whereas their primary structures are more eukaryotic in nature.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-072X
    Keywords: Archaebacteria ; Haloarcula vallismortis ; Glyceraldehyde 3-phosphate dehydrogenase ; Halophilism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Glyceraldehyde 3-phosphate dehydrogenase (EC 1.2.1.12) from the extremely halophilic archaebacterium Haloarcula vallismortis has been purified in a four step procedure to electrophoretic homogeneity. The enzyme is a tetramer with a relative molecular mass of 160000. It is strictly NAD+-dependent and exhibits its highest activity in 2 mol/l KCl at 45°C. Amino acid analysis and isoelectric focusing indicate an excess of acidic amino acids. Two parts of the primary sequence are reported. These peptides have been compared with glyceraldehyde 3-phosphate dehydrogenases from other archaebacteria, eubacteria and eucaryotes. The peptides show a high grade of similarity to glyceraldehyde 3-phosphate dehydrogenase from eucaryotes.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 159 (1993), S. 90-97 
    ISSN: 1432-072X
    Keywords: Archaebacteria ; Halobacterium salinarium ; Glutamine synthetase ; Cytidylylation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Glutamine synthetase (GS) was purified to electrophoretic homogeneity from the halophilic archaebacterium Halobacterium salinarium. The enzyme was purified 300-fold to homogeneity with 30% yield. By gel filtration and SDS gel electrophoresis, it was shown that the enzyme has a native molecular weight of 495,000 and a subunit molecular weight of 62,000. This indicates an octameric quaternary structure. The amino acid composition and the isoelectric point of 4.9 are similar to other GSs. The enzyme shows highest stability in 4 M NaCl or KCl and at temperatures up to 45°C. Lower salt concentrations or higher temperatures lead to rapid and irreversible denaturation. By low concentrations of Mg2+ or Mn2+, the salt dependence was decreased and the thermostability increased. Mg2+ or Mn2+ are essential cofactors. The two resulting activities show differences in pH and salt concentrations required for optimal activity, different K m-values and different sensitivity to inhibition by amino acids. The enzyme is not adenylylated like the GS from some eubacteria but cytidylylated. The covalently bound CMP increases Mn2+-and Mg2+-dependent activities at a different extent.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Molecular genetics and genomics 208 (1987), S. 523-528 
    ISSN: 1617-4623
    Keywords: EF-Tu ; Nucleotide sequence ; Archaebacteria ; Phylogeny
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A restriction fragment enrichment procedure was devised for the identification and cloning of the gene for protein synthesis elongation factor Tu (EF-Tu) from Methanococcus vannielii, employing hybridisation with an internal tufB gene probe from Escherichia coli. Methanococcus contains a single tuf gene on its chromosome; it is expressed in E. coli and it codes for a polypeptide of 46.5 kDa. The overall architecture of the protein bears a striking resemblance to that of eukaryotic elongation factor 1α (EF-1α). The close similarity to EF-1α is supported by the sequence homology values which are in the range of 34% to 35% with eubacterial, plastid and mitochondrial EF-Tu sequences and as high as 52% to 54% with those from eukaryotic EF-1α.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 180 (1974), S. 341-350 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Minute amounts of white or brown adipose tissue can be localized in situ within seconds by covering the organ surfaces with an alkaline solution of dithizon (diphenylthiocarbazone) in alcohol and water. The adipose tissues stain deep green, while the other organs remain unstained, or appear in various shades of pink and red. This technique has been successfully applied to various groups of vertebrates (mammals, birds, reptiles, amphibians and fishes), and it works in fresh, in deep frozen and in formalin-fixed specimens. It fails after tissue fixation in mercuric chloride-containing fluids. In vitro studies show that the staining reaction is due to (1) a preferential solubility of small amounts of dithizon in adipose tissue lipids, and (2) the development of a green color, which appears when dithizon dissolves in lipids or organic solvents.
    Additional Material: 2 Tab.
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  • 6
    Electronic Resource
    Electronic Resource
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 53 (1993), S. 234-241 
    ISSN: 0730-2312
    Keywords: Breast cancer risk ; chemoprevention ; intermediate biomarkers ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Early phase chemoprevention trials differ from standard therapeutic clinical trials because asymptomatic, healthy people are treated with a potentially toxic intervention for a prolonged period of time. Current subject selection protocols have relied upon epidemiological methods to identify highrisk individuals. Most available data provide risk estimates for various individual risk factors, but few have reported risk estimates for combinations of risk factors. Selection criteria for the large tamoxifen intervention trial (NSABP P1) were developed from the work of Gail et al. [1]. The Gail model takes into account non-genetic factors (e.g., nulliparity, age at menarche, preexisting pathological conditions) and genetic factors (family history). Using a lifetime risk of 10% of developing breast cancer as a standard to intervention trial. This approach has been criticized for being insufficiently selective (i.e., all women ≥60 yrs), but appears to be the best available method to select subjects for a chemoprevention trial. Other approaches have been based on identification of very high-risk women with acknowledged pathologic conditions [lobular carcinoma in situ, ductal carcinoma in situ (DCIS)]. Attempting to use these proliferative lesions as pathologic endpoints for drug effect has not been attempted. DCIS as a risk factor for tamoxifen intervention was excluded because of controversies over its management and because of frequent difficulties in distinguishing microinvasive from non-invasive lesions. Women treated for early stage breast cancer (Stage I) may be subjects for early stage chemopreventive interventions.We propose the use of intermediate endpoint biomarkers and genetic markers as entry criteria for early phase chemoprevention trials. For colorectal cancer chemoprevention, we have used a two-step selection process. The first step was based on epidemiologic risk assessment. Entry into the study required that a potential intermediate biomarker be positive and quantifiable. The relationship between modulation of a pre-transformational biomarker and development of cancer ultimately needs proof in a primary interventional trial; however, this methodology may permit screening of potential chemopreventive agents at lower cost and more rapid turn-around times. In early chemopreventive agent testing for breast cancer chemoprevention, we propose a similar two-step procedure. Epidemiological and/or pathological criteria for risk would be followed by a procedure to obtain cellular material. The cellular material would be assayed for pre-transformational cellular change.Identifying predictive genes in familial breast cancer cohorts such as the modified BRCA1 gene promises to select individuals at high familial and potentially physiological or environmental risk. The identification of the abnormal gene product in individuals and families will provide another important group of subjects for chemopreventive interventions. The identification of high-risk subjects for breast cancer chemoprevention, particularly those with familial genetic risk, carries important ethical problems. Such women may have difficulties obtaining health and life insurance, deciding to have children, and obtaining work. Chemoprevention trials with genetic selection criteria will need to develop methods of dealing with these issues.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 151 (1977), S. 299-313 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The mandibular symphysis of rorqual whales, whales of the genera Megaptera and Balaenoptera, is characterized by a Y-shaped fibrocartilage structure that lies in the substance of the muscular ventral pouch of these animals. The stem of the structure joins with the symphysis and is usually indicated externally by an unfurrowed median strip of blubber that has been called the “cutwater” by earlier writers. The arms of the Y pass back and are superficially indicated in all rorqual whales as a ridge running parallel to the rami of the mandibles. This fibrocartilage skeleton of the pouch is most closely related to the mylohyoid muscle. The function of the fibrocartilage Y is probably linked with the jaw mechanics of these whales, but its precise function is otherwise not known.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 162 (1981), S. 23-33 
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The thin limbs of short and long loops of Henle of the desert rodent Psammomys obesus were studied by freeze-fracture techniques. Intercellular junctions and internal membrane characteristics of thin-limb epithelia are of interest with regard to the high urine-concentrating capacity of this animal.The epithelium of the descending thin limbs of short loops is remarkably undifferentiated and equipped with multistrand tight junctions. In the descending thin limb of long loops, two segments are to be distinguished. The upper parts are characterized by an extensive cellular interdigitation and single-strand tight junctions. Thus, the paracellular pathways are prominent from two aspects: the junctional belt is elongated by interdigitation, and its apico-basal depth is shallow. The transition from the upper to the lower part appears to be abrupt, as indicated by the change in intramembrane particle density. The lower parts are characterized by a noninterdigitating epithelium with junctions consisting of few, but always more than two, strands. In addition, this thin-limb segment is characterized by regularly distributed infoldings of the basal cell membrane. The ascending thin limbs are established by an interdigitating epithelium, with junctions generally consisting of one strand. Once again, the elongated junctional belt is shallow.This study presents further evidence that remarkable species differences occur among thin-limb epithelia, especially concerning the descending thin limbs of long loops. Those differences may well explain discrepant functional findings concerning the transport properties of this segment in various species.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 36 (1964), S. 221-227 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Dixon-Ringe sind Füllkörper aus Drahtgewebe. Die Eigenschaften solcher Füllringe beim Rektifizieren werden an Hand von Meßwerten diskutiert. Sodann wird über Erfahrungen bei der Verwendung in technischen Kolonnen berichtet.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 40 (1968), S. 154-159 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Von den H2/O2-Brennstoffzellen sind derzeit die mit alkalischem Elektrolyten am weitesten für eine Verwendung zum Antrieb von Straßenfahrzeugen entwickelt. Der Wasserstoff muß dabei in Druckflaschen mitgeführt oder in einem kleinen Reformer erzeugt werden. Verbesserungen sind durch die Möglichkeit der Nutzbremsung, einen Parallelbetrieb zwischen Brennstoffzelle und Blei-Batterie und durch Ausnutzung der Ruhezeit des Autos zur Wiedergewinnung der Brennstoffe in Kleinelektrolyseuren zu erwarten. Als Beispiel dient ein Elektrofahrzeug mit 10 kW Antriebsleistung und 22,4 kWh Energievorrat, ausreichend für 2,25 Fahrstunden am Tag, aufgeteilt auf 175 Fahrzyklen bei 400 m Haltestellenabstand (Gesamtfahrstrecke 70 km).
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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