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  • 1
    Electronic Resource
    Electronic Resource
    Effect of alteration of the acetic acid synthesis pathway on the fermentation pattern of escherichia coli (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 38 (1991), S. 1318-1324 
    Details
    ISSN: 0006-3592
    Keywords: glucose metabolism ; pet operon ; E. coli ; fermentation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The glucose metabolism of an Escherichia coli strain bearing mutations abolishing both acetyl phosphotransferase (PTA) and acetate kinase (ACK) activities was studied under aerobic and anaerobic conditions. These studies were conducted in a complex medium with the mutant carrying no plasmid, the mutant carrying the common cloning vector pUC19, and the mutant carrying a plasmid bearing the “pet” operon that encodes Zymomonas mobilis pyruvate decarboxylase and alcohol dehydrogenase activities. The mutant carrying no plasmid showed lower specific growth and glucose uptake rates relative to the parent wild-type strain (K-12), Lactic acid was produced at higher levels than the wild type, and considerable amounts of pyruvic acid were secreted as an unusual byproduct. Analysis of other fermentation products showed low but significant amounts of acetic acid, no accumulation of formic acid, and lower secretion of succinate and ethanol. The maintenance of the plasmid pUC19 in the mutant negatively affected metabolism. Expression of the pet operon overcame the metabolic stress caused by the plasmid, enhancing growth and glucose uptake rates to the values observed in the plasmidfree mutant. Also, expression of the pet operon allowed consumption of pyruvate accumulated during the first hours of fermentation.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260381109
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  • 2
    Electronic Resource
    Electronic Resource
    Influence of expression of the pet operon on intracellular metabolic fluxes of Escherichia coli (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 39 (1992), S. 59-65 
    Details
    ISSN: 0006-3592
    Keywords: pet operon ; E. coli ; metabolic fluxes ; metabolic engineering ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Fermentation patterns of Escherichia coli HB101 carrying plasmids expressing cloned genes of Zymomonas mobilis pyruvate decarboxylase (PDC) and alcohol dehydrogenase li (ADH) were determined in glucose-limited complex medium in pH-controlled anaerobic batch cultivations. Time profiles of glucose, dry cell weight, succinate, formate, acetate, and ethanol were determined, as were the activities of ADH and PDC. Fluxes through the central carbon pathways were calculated for each construct utilizing exponential phase data on extracellular components and assuming quasi-steady state for intermediate metabolites. Overall biomass yields were greatest for cells expressing both PDC and ADH activities. Yields of carbon catabolite end products were similar for all PDC-expressing strains and different from those for other strains. Relative to its glucose uptake rate, the strain with greatest PDC and ADH activities produces formate and acetate more slowly and ethanol more rapidly than other strains. Strong influences of plasmid presence and metabolic coupling complicate detailed interpretations of the data.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260390110
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  • 3
    Electronic Resource
    Electronic Resource
    Vascular networks from explants of human synovialis in vitroSupported in part by grant AM-02520 from the National Institute of Arthritis and Metabolic Diseases, NIH Bethesda, Maryland, and by private funds from Southwestern Clinic & Research Institute, Inc. (1963)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 147 (1963), S. 525-531 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Explants of human synovialis obtained surgically were cultivated under dialysis membrane in the multipurpose Rose chamber and in Eagle's medium enriched with 20% pooled human cord sera. Within 24 hours monocytes and lymphocytic cells emerged from the majority of explants while spindle and stellate cells appeared later on the second and third days of culture. A monolayer of cells developed in which active mitosis was observed. Between 12 to 15 days, fingerlike projections of cells adjacent to the explants branched out between the cover glass and the monolayer of mesenchymelike growth and by the twenty-fifth day had developed into anastomosing networks eventually ranging in length from 1.2 to 3.2 mm. Ciné and still phase photomicrographs decumented findings. Vascular networks developed in vitro in 85% of the total 80 Rose chambers examined over an average period of 58 days. Minute vessels, patent for only short distances, were lined with endothelial cells characterized by slender elongated nuclei and with two or three small nucleoli. In contrast, flanking fibroblasts were considerably larger with clear oval nuclei containing conspicuous nucleoli. Differential stains demonstrated reticular fibers and distinct bundles of collagen lying along the vessels, particularly in the area adjacent to the fragment. In the study of rheumatoid arthritis, where vascular lesions are known to occur, it is possible that such preparations may provide favorable test objects.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1091470407
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  • 4
    Electronic Resource
    Electronic Resource
    Effects of cold shock and phospholipase A2 on intact boar spermatozoa and sperm head plasma membranes (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 26 (1990), S. 143-149 
    Details
    ISSN: 1040-452X
    Keywords: Fertility ; Ca2+ uptake ; Head plasma membrane ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Head plasma membranes (HPM) isolated from cryopreserved boar spermatozoa show an excessive fluidization (Buhr et al., Gamete Res 23:441-449, 1989), which might be involved in the loss of fertility. The current study assessed the ability of cold shock (5°C) and phospholipase A2 (PA2) to duplicate these effects on membrane structure and to affect 45Ca2+ uptake and gross morphological characteristics of whole, fresh boar sperm. The HPM from cold-shocked sperm showed a significantly greater rate of fluidization over time than did HPM from control sperm. Addition of PA2 (bee or snake venom, 0.1 or 10.0 ng/ml) to HPM from control sperm caused fluidization similar to cold shocking, but to a lesser degree (P 〈 0.05). Cold-shocked intact sperm exhibited severe acrosomal disruption, loss of motility, and increased 45Ca2+ uptake relative to control sperm. Addition of PA2 (bee or snake venom, 0.1, 1.0., 10.0, and 1,000 ng/ml) to control sperm had not effect on gross morphology or motility while maintaining or increasing sperm extrusion of 45Ca2+. Therefore, although PA2 can, to some extent, duplicate the effects of cold shock on HPM molecular organization, its lipid hydrolytic action is insufficient to cause all the gross disruptions of severe thermal shock. Both PA2 and cold shock disrupted HPM structure, but only cold shock increased 45Ca2+ uptake, suggesting that cold shock may be increasing 45Ca2+ uptake in areas other than the head. Cold shock disrupts sperm on three levels; membrane molecular organization, intracellular Ca2+ regulation, and gross morphology/motility.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1080260208
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  • 5
    Electronic Resource
    Electronic Resource
    Effects of ethanol dehydration and critical point drying on fish tissue culture cell membrane elemental composition by scanning electron microscopy/X-ray microanalysis (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Microscopy Research and Technique 28 (1994), S. 259-260 
    Details
    ISSN: 1059-910X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jemt.1070280310
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  • 6
    Electronic Resource
    Electronic Resource
    Effects of semen preservation on boar spermatozoa head membranes (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 23 (1989), S. 441-449 
    Details
    ISSN: 0148-7280
    Keywords: boar ; spermatozoa ; membrane fluidity ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Head plasma membranes were isolated from the sperm-rich fraction of boar semen and from sperm-rich semen that had been subjected to three commercial preservation processes: Ex tended for fresh insemination (extended), prepared for freezing but not frozen (cooled), and stored frozen for 3-5 weeks (frozen-thawed). Fluorescence polarization was used to determine fluidity of the membranes of all samples for 160 min at 25°C and also for membranes from the sperm-rich and extended semen during cooling and reheating (25 to 5 to 40°C, 0.4°C/min). Head plasma membranes from extended semen were initially more fluid than from other sources (P 〈 0.05). Fluidity of head membranes from all sources decreased at 25°C, but the rate of decrease was significantly lower for membranes from cooled and lower again for membranes from frozen-thawed semen. Cooling to 5°C reduced the rate of fluidity change for plasma membranes from the spernvrich fraction, while heating over 30°C caused a signifi cantly greater decrease. The presence of Ca++ (10 mM) lowered the fluidity of the head plasma membranes from sperm-rich and extended semen over time at 25°C but did not affect the membranes from the cooled or frozen-thawed semen. The change in head plasma membrane fluidity at 25°C may reflect the dynamic nature of spermatozoa membranes prior to fertilization. Extenders, preservation processes and temperature changes have a strong influence on head plasma membrane fluidity and therefore the molecular organization of this membrane.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1120230409
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