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  • 1995-1999  (60)
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  • 1998  (60)
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  • Life Sciences  (208)
  • 1
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: No Abstracts.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 18 (1998), S. 92-92 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: No Abstracts.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 18 (1998), S. 108-108 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: No Abstracts.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 18 (1998), S. 95-106 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: An enzymatic process to decrease the phenolic content in canola meal was investigated. The new method was based on the addition of an enzyme preparation from the white-rot fungus Trametes versicolor to concentrated meal-buffer slurries. This approach eliminated the extraction of the valuable meal components such as proteins and carbohydrates. Two systems were considered: (i) slurries with canola meal concentrations higher than 33% [w/v]; (ii) slurries with canola meal concentrations equal to or less than 12.5% [w/v] with n-hexane as the main component of the continuous phase.The concentration of sinapic acid esters decreased by 99% after a 1.5, 2 and 3 hour long treatment of the meal with an initial moisture content of 75% at 90°C, 70°C and 50°C, respectively. The process was carried out at temperaturs as high as 110°C. Both the enzyme and the moisture concentrations influenced the enzymatic process and their action was coupled. The concentration of oxygen strongly affected the process.The enzymatic process was able to be carried out in the presence of hexane as the main component of the continuous phase. The optimum temperature for such a process was 30-40°C, At 30°C, after 1 h of treatment, the meal phenolic content was decreased by 97%. The water uptake by the meal was diminished in the presence of hexane.
    Additional Material: 6 Ill.
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  • 5
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: No Abstracts.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: TNM-FH Lepidopteran insect cell culture medium containing 10% fetal bovine serum (FBS), while allowing limited vegetative growth of Paenibacillus larvae (wild-type strain), the causative agent of American foulbrood, contained no viable vegetative cells upon subculture, nor were any heat resistant spores produced in this medium alone. However, TNM-FH medium cotaining embryonic or midgut cells from Trichoplusia ni, hemocytes from Estigmene acrea, ovarian and embryonic cells from Spodoptera frugiperda, embryonic cells from Plutella xylostella, Spodoptera exigua and Pseudaletia unipuncta or ovarian cells from Lymantria dispar, supported both heavy vegetative cell growth and moderate production of heat resistant spores. EX-CELL 405 serum-free insect cell culture medium alone appeared to contain the appropriate nutrients required for both vegetative growth and sporulation of P. larvae. However, in the presence of embryonic cells from T. ni, limited vegetative growth occurred and the P. larvae cells appeared to die off. This was confirmed by the fact that no colony growth occurred upon subculture, nor were any heat resistant spores detected. This was true also in the presence of fat body cells from T. ni, except that a limited number of spores (4,000/ml) were detected in the form of cology-forming units (CFU) on plates following heating to 80°C for 20 minutes. In a parallel study with a wild-type strain of Bacillus popilliae, vegetative cells grew only in TNM-FH medium in the presence of mid-gut BTI-Tn-MG and ovarian (Tn-368) cells of T. ni. No heat resistant spores, however, were detected in any of the cultures. When BTI-Tn-MG and Tn-368 cells were further challenged with four variant cultures of B. popilliae, vegetative growth and limited sporulation were achieved. The BTI-Tn-MG cell line in TNM-FH medium produced as many as 12,000 spores/ml after 21 days in culture.
    Additional Material: 5 Tab.
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  • 7
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The conversion of starch from unhydrolyzed cassava flour to ethanol by a pure culture of Endomycopsis fibuligera and by a co-culture of this amylolytic yeast and the bacterium Zymomonas mobilis was studied.The best overall results were obtained using the mixed culture. After 96 h of fermentation of a medium containing 150 g/l initial cassava starch, an ethanol concentration of 31.4 g/l, a productivity of 0.33 g ethanol/l × h and a yield of 0.21 g ethanol/g initial starch were reached. The highest yield (0.37 g/g) was obtained after 48 h when using a medium containing 50 g/l initial starch.
    Additional Material: 2 Ill.
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  • 8
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: No Abstracts.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 18 (1998) 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: No Abstracts.
    Type of Medium: Electronic Resource
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  • 11
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: No Abstracts.
    Type of Medium: Electronic Resource
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  • 12
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: No Abstracts.
    Type of Medium: Electronic Resource
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  • 13
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: No Abstracts.
    Type of Medium: Electronic Resource
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  • 14
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The attachment, growth and product synthesis of non-flocculating Zymomonas mobilis cell, fixed in stainless steel wire spheres (WS), were investigated. The carrier surface was activated by treatment with titanium (IV) chloride (TiCl4) and γ-aminopropyltriethoxysilane (AS) in an attempt to raise the efficiency in the immobilization of the cells. System productivity for ethanol and levan production, using cells immobilized on a modified stainless steel in the batch fermentation of a sucrose medium, rose as a result of increased biomass compared to the productivity of cells fixed on untreated (control) metal surfaces. Stabilized ethanol synthesis was demonstrated in the course of four cycles (each cycle 48 h) of repeated fermentations with a stainless steel carrier treated with AS, and three cycles when TiCl4 was used. Levan synthesis decreased after three cycles with cells immobilized on a silanized surface. System productivity for ethanol and levan production after the fourth cycle in experiments with TiCl4-activated, silanized and unmodified carriers were Qeth = 1.01, 1.06 and 0.27 g/l × h; Qlev = 0.32, 0.29 and 0.12 g/l × h, respectively. However, the specific productivity of biomass for product synthesis was higher in fermentation systems with untreated stainless steel surfaces, probably due to some loss of physiological activity of cells attached to a modified carrier. Investigations of throughly washed activated stainless steel wire surfaces, by scanning electron microscopy after immobilization, showed significant attachment of cells to the carriers. A polymer layer covered the wire surface treated with TiCl4 after fermentations. This may be explained as the binding of extracellular polysaccharide, such as the fructose-polymer levan and yeast extract components, to the modified support via chelation. After four fermentations, craters and holes in the polymer layer were evident, probably as a result of CO2 formation. A small number of cells appeared on this layer. In view of the good ethanol formation during all fermentation cycles, it is probably that active Z. mobilis cells remained under the polymer layer. Wire treatment with AS resulted in the formation of long filamentous cells during fermentation and some disturbance of cellular fission. This may be partly explained by strong electrostatic interactions between the positively charged carrier surface and the predominately negatively charged surface of Z mobilis cells. However, this did not significantly affect other cellular functions. The surface of the wire treated with AG was practically without a polymer layer.
    Additional Material: 6 Ill.
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  • 15
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 18 (1998), S. 157-166 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Different cultural parameters that regulate pectinolytic enzyme production in vitro by Trametes trogii were studied. When grown in a medium containing pectin, T. trogii produced extracellular polymethylgalacturonase, polygalacturonase and pectin lyase but no pectate lyase activity. No significant differences in the maximum enzyme activities measured were observed with the addition of xylan, carboxymethylcellulose or both to the medium containing pectin. The addition of glucose to that medium considerably decreases all the activities studied, and in a medium with glucose as the sole carbon source no galacturonase activity could be measured, and pectin lyase activity was at its minimum. The low synthesis of pectin lyase in cultures containing glucose suggests that this enzyme is constitutive in contrast to the polygalacturonases that were not detected. The increase in pectin concentration stimulated growth and enzyme production. The highest specific activities were attained with the greatest concentration tested (15 g/l). Casamino acids were the best nitrogen source for enzyme production. Maximum growth was measured at pH 3.3; pH values of around 4.5 stimulated enzyme production, but high pectinase activities were also detected in media with more alkaline initial pH values (6.2 for galacturonases and 6.6 for lyases), probably owing to the specific induction of particular isoforms. In the range of 23 to 28°C, good results were obtained in growth as well as in enzyme production. The addition of Tween 80 promoted growth and gave the highest yield of polymethylgalacturonase and pectin lyase (0.37 and 36.2 E.U./ml, respectively). The highest polygalacturonase activity (1.1 E.U/ml) was achieved with polyethylene glycol. Tween 20 and Triton X-100 inhibited growth and pectinase production.
    Additional Material: 4 Ill.
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  • 16
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 18 (1998), S. 167-174 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Zymomonas mobilis strain 113 “S” produces levan - an extracellular, viscous, biologically active, non-toxic fructose polymer with a unique structure and extraordinary properties. This polysaccharide was isolated at two different degrees of purity by alcohol precipitation from aqueous solutions and was characterized with respect to some rheological properties and stability of viscous solutions.The effects of temperature, pH and salt concentration on the viscosity of 1-3% levan solutions were examined. The viscosity of levan solutions was found to be quite stable and reversible at room temperature over a wide range of pH from 4 to 11. The viscosity was slightly affected by increased salt concentration. Levan solutions were rather stable at high temperatures (up to 70°C, 1 h, pH 6), where the viscosity could be almost completerly restored (up to 80-100%). Therefore, the degradation of the polymer structure under these conditions is probably insignificant. Temperatures of 70-100°C with a pH of less than 3.5 caused irreversible degradation of the levan structure.The above-mentioned properties of levan, obtained from Zymomonas mobilis 113 “S”, demonstrated the potential for the development of various therapeutic forms of pharmacologically-active levan and their application in medicine as well as in the food and other industries.
    Additional Material: 3 Ill.
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  • 17
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 18 (1998), S. 176-176 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: No Abstracts.
    Type of Medium: Electronic Resource
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  • 18
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 18 (1998), S. 179-188 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The extractive purification of peroxidase from Armoracia rusticana roots and Glycine max seed coats in temperature-induced and affinity microsphere-containing aqueous two-phase systems was stuied. The extractive purification of peroxidase from Glycine max seed coats was carried out in a temperature-induced aqueous two-phase system formed by Triton X-45, Triton X-100 and sodium acetate at pH 5.5 A 99% yield with a 6-fold purification factor was obtained. When the clear top phase was subjected to concanavalin-A affinity chromatography, the purification factor rose to 41 and the yield dropped to 28%.A two-step purification process for peroxidase from Armoracia rusticana roots was developed by adding concanavalin-A affinity microspheres to a PEG/phosphate aqueous two-phase system. The method allows a 60% recovery of high purity peroxidase (1,860 guaiacol units per mg). A lower recovery rate and degree of purification of this enzyme was achieved after temperature-induced aqueous two-phase partition or acetone precipitation and concanavalin-A affinity column chromatography.
    Additional Material: 1 Ill.
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  • 19
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 18 (1998), S. 189-200 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Endo-β-glucanase (endo-β-1,4-glucano-glucanase EC 3.2.1.4), isolated from Trichoderma reesei, was immobilized in calcium alginate beads, retaining 75% of its original activity. The polyanionic moiety surrounding the immobilized enzyme displaced the pH-activity profile to alkaline regions with respect to that of the free enzyme. The enzyme was inhibited by carboxymethylcellulose, but this inhibition appeared to be decreased by immobilizatíon. The enzyme immobilized in alginate beads showed a Km value (1.02% w/v) lower than that of the enzyme (1.31%). The apparent Vmax of immobilized cellulase preparations (238.3 μmol glucose/ml × h) decreased by a factor of 0.59 with respect to that of the soluble enzyme. The optimum temperature (60°C) of the free and entrapped enzymes remained unaltered. In contrast, the half-life of the endoglucanase immobilized in calciumalginate beads was 4.6 h at 55°C and 5.4 h at 60°C, while that of the free enzyme was 3.0 h at 55°C and 1.2 h at 60°C. A technological application of the immobilized enzymes was tested using wheat straw as a source of fermentable sugars. The hydrolytic degradation of straw, by means of a crude extract of free and immobilized cellulases and β-glucosidase, released a large amount of reducing sugars from wheat straw after 48 h (between 250-720 mg glucose/g straw), carrying out more than a 90% saccharification. A mixture of immobilized β-glucosidase and free cellulases maintained 80% of the activity of the soluble counterparts, and the co-immobilization of both types of enzymes reduced by hydrolytic efficiency to half.
    Additional Material: 5 Ill.
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  • 20
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 18 (1998), S. 201-229 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The specific aspects of airlift reactors emphasizing their function relevance to particular application as bioreactors are presented.The two main groups of airlift reactors - external-loop and concentric-tube reactors - were investigated on a pilot-plant scale with regard to their performance during the cultivation of unicellular and filamentous microorganisms which produce Bacitracin, Cephalosporin C and Nystatin. Some results were compared to those obtained in conventional stirred tank bioreactors. The comparison was carried out based on physical properties (oxygen transfer rate (OTR), volumetric mass transfer coefficient (kLa) and efficiency of oxygen transfer (EO2)), cell mass, productivity and substrate consumption, secondary metabolite production, and efficiency of the product formation with regard to the specific power input.It was shown that B. licheniformis, C. acremonium and S. noursei fermentations occurred similarly to those performed in stirred vessels, proving that the capacity of the airlift bioreactors surpassed the problems which arise from the morphology and rheology of the broths. From the chemical engineering point of view, it was obvious that the primary tasks of a bioreactor (uniform distribution of microorganisms and nutrients over the entire fermenter volume, appropriate supply of biomass with nutrients and oxygen) were fulfilled by the airlift bioreactors tested. In addition, the efficiency of oxygen transfer (OTR referred to power input) in the airlift fermenters proved to be about 38% higher than in the stirred tank bioreactors (expressed as average values), while the sorption efficiency (OTR referred to antibiotic production) was found to be 22% greater in the airlift system than in an STR.Therefore, the biosyntheses were performed with about a 30-40% increase in energy efficiency and energy savings compared to the conventional system.Moreover, the lack of mechanical devices in the airlift system provides greater safety and a gentler environment for the cultivation of microorganisms.
    Additional Material: 18 Ill.
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  • 21
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 18 (1998), S. 231-240 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: In various bacterial strains belonging to the β-subdivision of proteobacteria which are capable of degrading chlorinated monoaromatic compounds, chlorocatechol 1,2-dioxygenase genes were detected by PCR and Southern hybridization. Using PCR primers derived from the conserved sequence motifs of chlorocatechol 1,2-dioxygenase genes tfdC, clcA and tcbC, PCR products of the expected size were obtained with the test strains, but not with negative control strains. The specificity of the PCR products was verified by hybridization using an oligonucleotide probe for an internal sequence motif which is evolutionarily conserved among chlorocatechol 1,2-dioxygenases and some other dioxygenases that catalyze the intradiol aromatic-ring-cleavage. Hybridization with the tfdC PCR product from the 2,4-D degradative plasmid pJP4 under stringent conditions revealed different extents of homology of the chlorocatechol 1,2-dioxygenase genes to the canonical tfdC sequence in the various strains. These findings were confirmed by the nucleotide sequence analysis of the tfdC-specific PCR products. From our results, we conclude that the PCR primer set is more suitable than the hybridization with pJP4-derived gene probes for the detection of diverse chlorocatechol 1,2-dioxygenase genes in proteobacteria.
    Additional Material: 3 Ill.
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  • 22
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 18 (1998), S. 243-254 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The degradation of lignocellulosic biomass of banana pseudoste was investigated during solid state fermentation (SSF) by P. ostreatus and P. sajor-caju. Both organisms proved to be efficient degraders of banana pseudostem biomass. P.ostreatus degraded hemicellulose (40% of dry weight, d.w.) better than cellulose (17.5% of d.w.) and lignin (10% of d.w.). P. sajor-caju also degraded hemicellulose (31% of d.w.) better than cellulose (12.4% of d.w.) and lignin (6% of d.w.). In both cases, a preferential removal of hemicellulose during the initial growth period and a delayed degradation of lignin were observed. The kinetics of cellulolytic, hemicellulolytic and lignolytic enzyme production in liquid culture were also examined. The activities of CMCase and β-glucosidase were highest at 16 days of growth and avicelase activity was at its maximum after 24 days (CMCase - 1.1 IU/ml, β-glucosidase - 0.09 IU/ml in the case of P. ostreatus; CMCase - 1.0 IU/ml, β-glucosidase - 0.087 - IU/ml in the case of P. sajor-caju.). Xylanase and laccase activity reached their maximum after day 16 and day 24 of incubation, respectively. (Xylanase - 1.1 IU/ml and laccase 3.0 IU/ml in the case of P. ostreatus; xylanase - 1.0 IU/ml and laccase - 3.6 IU/ml in the case of P. sajor-caju.). The efficient degrading capacity of test fungi demonstrated their potential use in the conversion of banana pseudostem biomass into mycelial protein-rich fermented animal feed.
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  • 23
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 18 (1998), S. 275-276 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: No Abstracts.
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  • 24
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Cell growth and organic acid production by Propionibacteria are dependent on the vitamin-nitrogen source in the culture medium. Final cell and propionic acid concentrations produced by Propionibacterium shermanii, using corn-steep liquor, were higher than those obtained utilizing yeast extracts. Since corn-steep liquor is much cheaper than yeast extract, the process becomes more attractive. By calculating the specific growth rates, it was observed that the critical propionic acid concentration, that prevents all growth (μX = 0), is different depending on the vitamin-nitrogen source used and its concentration. For example, for 5.0 and 15.0 g/l Oxoid yeast extract, those critical propionic acid concentrations were 16.0 and 27.0 g/l, respectively. Such propionic acid concentrations inhibit the cell growth, but not the formation of acid. The specific propionic acid production rate also indicates that the critical concentration for metabolic activity, when propionic acid is no longer produced (μP = 0), varies according to the vitamin-nitrogen source and its concentration in the medium. For 5.0 and 15.0 g/l Oxoid yeast extract, those concentrations were 22.1 and 30.1 g/l, respectively.
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  • 25
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: No Abstracts.
    Type of Medium: Electronic Resource
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  • 26
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The fermentation process of acid curd whey using pure cultures of L. bulgaricus and L. acidophilus was investigated. The influence of the starter culture amount on the acidification rate in the fermentation was specified, the biological value of fermented and fermented-ammoniated curd whey was determined, and the ability of fermented whey to prevent the injurious effect of Bac. mesenthericus on the wheat bread quality was examined.Acid curd whey was fermented up to a titratable acidity of 19.8-21.6 g lactic acid/kg whey using L. acidophylus and L. bulgaricus. Mathematical equations were developed on the basis of experimental data to calculate the titratable acidity (A) as a functionof fermentation time (τ) and temperature (t). Fermentation and fermentation-ammoniation processes increase the biological value of whey (the content of the vitamins B1, B2, B6, PP and the free amino acids increase). A new dry fodder BIOLAKTS was developed from fermented curd whey and was recommended for use in veterinary medicine. The fermentation-ammoniation process of curd whey was carried out by adding calculated amounts of non-protein nitrogen NH4OH to increase the total protein equivalent and to achieve mutual proportions of protein and lactose 1:1.4, as in skimmed milk. Fermented-ammoniated curd whey was used to obtain a skimmed milk substitute. A dry flour lactic acid concentrate (FLC) was created as a mixture of high quality wheat flour and evaporated fermented whey in established ratios. As our experiments prove, it can be used as an additive in bread-making to prevent the spoiling of wheat bread by Bac. mesenthericus.
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  • 27
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 18 (1998), S. 305-313 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: For the purpose of forming cells possessing more than three nuclei and of determining the factors inducing multinucleation, cells of Saccharomyces cerevisiae were treated with 0, 0.3, 0.5, and 1.0% [w/v] colchicine solution, with and without shaking. When the cells were treated with 1.0% [w/v] colchicine solution, the number of cells containing two to eight nuclei was the largest. The multinucleate cells could grow on potato dextrose agar medium and their multinucleate nature did not disappear for at least three generations. This means that such cells are genetically stable. The proliferation rate of the multinucleate cells was not superior to that of the original strain. However, by monitoring the weight loss of the flask, it was possible to indirectly estimate the increase in the alcohol production of the multinucleate cell. It was concluded that the shaking treatment and higher colchicine concentrations contributed to multinucleation.
    Additional Material: 3 Ill.
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  • 28
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 18 (1998), S. 315-324 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Candida rugosa was cultivated in a mixed-solid substrate containing coconut oil cake (COC) and fine and coarse wheat bran (1:1:1) with an initial water activity (aw) of 0.92. The substrate was modified by adding a mineral solution (5%), corn steep liquor (6%), maltose (2%), peptone (3%), olive oil (10%), gum arabic (0.4%), different fatty acids (0.3%) and Tweens (0.5%). Fermentation in a column fermenter significantly improved the lipase yield to 118.2 Units per gram of dry fermented substrate [U/gds] at 72 h. This result was obtained 24 hours earlier than in our former studies (87.76 U/gds at 96 h) in COC, and the yield showed a 38% increase. Growth was measured indirectly by determining the glucosamine content in the cell wall of the yeast contained in the fermented matter, after its hydrolysis.
    Additional Material: 6 Ill.
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  • 29
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 18 (1998), S. 327-338 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The batch production of gluconic acid in the presence of glucose, sucrose and molasses was investigated using free mycelia of Aspergillus foetidus NRRL 337 in shake flasks. Eight growth parameters were chosen as independent variables. The temperature, pH, substrate type and initial concentrations, inoculum percentage and shake rate directly affected the specific microorganism growth and gluconic acid production rates. The optimum temperature and initial pH values were found to be 33°C and five to six, respectively. The maximum specific growth and gluconic acid production rates were established as 57 g/dm3 of glucose, 75 g/dm3 of sucrose and 150 g/dm3 of molasses. The optimum values of the shake rate, inoculum percentage and initial ammonium nitrate concentration were determined as 100 1/min, 0.5% and 1.5 g/dm3, respectively. The maximum gluconic acid concentrations corresponding to these initial substrate concentrations were observed to be 8.3 g/dm3, 17.4 g/dm3 37.0 g/dm3, respectively. The optimum specific microbial growth and gluconic acid production rates were found as 0.0145 1/h and 0.0375 g/g × h, respectively, for the fermentation conditions of SGo = 57 g/dm3, T = 28°C, initial pH = 6.5, N = 84 1/min, A = 0.5 g/dm3 and I = 0.5%.
    Additional Material: 3 Ill.
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  • 30
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 18 (1998), S. 339-351 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Covalent immobilization of thermostable α-amylases from catabolite resistant and sensitive Bacillus licheniformis strains on controlled pore glass (CPG) and porous silica (Spherosil) beads and ionic binding on DEAE-cellulose, Amberlite and Dowex were investigated. Preparations with satisfactory operational stabilities and activities up to 1,600 U/g of support (ionic binding) and 800 U/g carrier (covalent coupling) were obtained. Immobilization led to a narrowing of the pH interval of maximum activity. The fixed amylases were stable in limited pH regions around the optimum pH level. An enhancement of the enzyme thermostability was observed. Apparent shifts of the optimum temperatures were not found. The apparent Vmax decreased up to 80 times. The Km′ remained unchanged (for amylopectin as the substrate) or increased up to 10 times (soluble starch). Maltose, maltotriose and maltopentaose were the main products of the hydrolysis. A significant increase in maltopentaose content was observed.
    Additional Material: 3 Ill.
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  • 31
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: No Abstracts.
    Type of Medium: Electronic Resource
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  • 32
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: No Abstracts.
    Type of Medium: Electronic Resource
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  • 33
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 18 (1998), S. 17-27 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Common theories of microbial growth and physiology are formulated exclusively in terms of the isolated microorganisms - especially bacteria. This is, however, an inadmissible simplification because it is obvious that the organization of microbial populations and colonies follows certain general rules.Bacterial colonies are able to generate complex interfacial growth patterns similar to those observed during diffusion-limited growth processes in non-living systems. One reason for these patterns is assumed to be the ability of many bacteria to swarm in an active manner on a substrate surface. Therefore the models of bacterial colony growth incorporate “random walkers”, which move actively in response to a gradient in the concentration of nutrients and communicate with each other by means of a chemotactic feedback.A selected number of yeasts were tested with regard to their colony growth patterns depending on the medium parameters such as nutrient concentration. Growth patterns similar to those which were described in literature for bacteria were also found in these experiments. It concerns in particular growth types like compact growth, fractal growth and dense-branching growth.This result allows a hypothesis to be formulated, that - especially in the case of fractal growth patterns - wandering of cells on a substrate surface may be induced by uncontrolled “swimming” on a thin water film caused by the metabolic activity (e.g. respiration) of the cells on the surface of the agar.Furthermore it was found that an interplay between changes in the individual morphology of yeast cells and the morphology transitions takes place. Such growth patterns are known for Candida sp. which are able to form pseudomycel and blastospores.
    Additional Material: 10 Ill.
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  • 34
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: No Abstracts.
    Type of Medium: Electronic Resource
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  • 35
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 18 (1998), S. 43-50 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Pioneering research efforts in the handling of municipal sewage in developing countries have involved the use of water hyacinth (Eichhornea crassipes) to purify sewage for possible re-use of the effluent water for domestic purposes. The ability of water hyacinth to remove pollution from raw sewage has been found to be impaired by sewage toxicity. Trials were therefore carried out to adapt water hyacinth to toxicity and thereby increase its ability to remove pollutants from raw sewage. The plants were adapted using an active bio-degrader consisting of Pseudomonas aeruginosa, Escherichia coli, Klebsiella ozaenae, Klebsiella edwardsiella and Baccillus subtilis. The adaptation progressed through 20, 40, 60 and 80% sewage dilution until plants capable of growth in 100% raw sewage were obtained. Plants were observed for morphological growth and at four weeks, samples were collected for tissue analysis.The plants progressively absorbed nutrients from sewage up to the fourth week, when signs of toxicity were obsereved through wilting, loss of turgidity and reduction in leaf number. However, plants that survived through a series of adaptations under various sewage dilutions exhibited luxuriant growth on raw sewage. In synergy with the active bio-degrader, the efficiency of the adapted water hyacinth to remove pollutants (nutrients) from raw sewage was enhanced by 93%.
    Additional Material: 4 Tab.
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  • 36
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    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 18 (1998), S. 53-62 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The root nodules of Melilotus alba DESR., a fodder legume, contained high amounts of IAA. A tryptophan pool present in the nodule might serve as a source of IAA production. Presence of IAA oxidase and peroxidase in the nodules indicated the metabolism of IAA, at least in part, in the nodules. The Rhizobium species isolated from the root nodules produced a high amount of IAA (190 μg/ml) from L-tryptophan supplemented basal medium. IAA production and microbial growth were coincident. The production of IAA by the Rhizobium sp. was increased by 315% when the medium was supplemented with lactose (1%), NiCl2 (10 μg/ml), cetyl pyridinium chloride (0.5 μg/ml) and glutamic acid (0.4%), in addition to L-tryptophan (3 mg/ml). The possible role of the rhizobial production of IAA on the rhizobia-legume symbiosis is discussed.
    Additional Material: 1 Ill.
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  • 37
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: In a prospective study, nuclear DNA was extracted from colorectal tumours and normal mucosa which had been fixed in buffered formalin and embedded into paraffin. DNA-extraction was performed using three different methods: a commercial kit which was not especially created for this use; a known fast procedure without DNA-cleaning steps; and a more conventional DNA-preparation protocol with DNA-cleaning. Using the polymerase chain reaction (PCR), DNA was amplified by being targeted onto two β-globin fragments with different lengths (536 bp and 989 bp) and (CA)n repeats localized on chromosome 5q (D5S346) and chromosome 17p (TP53CA) with a length of about 100 bp for detection of microsatellite instability. The success rate of microsatellite amplification was 100% with all methods. The 536 bp β-globin fragment could be amplified with a success rate ranging from 40% to 100%. The amplification of the 989 bp β-globin fragment was unsuccessful. Significant differences were observed between the three methods in the final DNA concentration and DNA yield. In microsatellite instability studies of paraffin-embedded tissues, the investigator can expect a high success rate of nearly 100% using any of the described methods.
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  • 38
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 18 (1998) 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 39
    Electronic Resource
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    Berlin : Wiley-Blackwell
    Acta Biotechnologica 18 (1998), S. 3-16 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The reusability of biomass in lactic acid batch fermentation with free cells of Lactobacillus paracasei was studied in a 2-1 fermenter and in a 50-1 fermenter. In lab-scale fermentation experiments, 33 to 100% of the cell mass formed was reused in the subsequent batch in each case. In a series of seven consecutive batches, maximum values of lactate formation productivity of 6.32 to 11.54 g/l × h were observed at initial cell concentrations of 2.1 to 24.6 g/l. In all of the experiments, the initial cell viability was 78% or greater than 78%, and the final cell viability did not fall below 70%. At cell concentrations above 20 g/l, the productivity of lactic acid formation did not increase further, but remained constant. Because its level could be influenced by varying the proportions between the content of yeast extract, peptone and initial cell mass (1:1:2, 1:1:1 and 3.3.1) in the medium and no inhibitory effects were observed, this finding can be attributed to nutrient limitation. A low degree of cell reuse was reached in an analogous series of experiments carried out in a 50-1 fermenter. In this case, the initial cell concentration varied between 0.5 and 1.1 g/l, and therefore cell growth was not limited by nutrients in the first period of fermentation. Lactate production was still stable after six cell-reuse operations. The lactic acid yield did not fall below 90%. Temporary storage of the biomass in a refrigerator for a time interval of one to two weeks caused no significant impairment of overall lactate production, but a proportional prolongation of the lag phase occurred with increasing duration of storage.
    Additional Material: 8 Ill.
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  • 40
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 18 (1998), S. 29-41 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: A 4-nitrophenol degrading strain PNP1 isolated from the El-Harrach River near Algiers (Algeria) was studied with respect to its growth behaviour. According to the morphological and biochemical characteristics this strain was assigned to Pseudomonas putida. Besides 4-nitrophenol, the strain also used 1,2- and 1,4-dihydroxybenzene, benzoate, 4-hydroxybenzoate and 3,4-dihydroxybenzoate as sources of carbon and energy, degrading them exclusively via the ortho pathway. Pseudomonas putida PNP1 degrades 4-nitrophenol through a purely oxidative pathway with release of the nitro group as nitrite. During cultivation with 4-nitrophenol in ammonium-containing mineral medium, the strain PNP1 grew optimally at pH 7 and at a temperature between 30 and 35°C and showed stoichiometric nitrite release (at pH 7 and 30°C MONOD model parameters μmax = 0.615 h-1 and KS = 0.145 mg/l). A phenomenological model for the description of growth inhibition at high 4-nitrophenol concentrations was derived (below 400 mg/l only weak inhibition and at 600 mg/l acute toxicity). In ammonium-free medium, the maximum specific growth rate was reduced to 0.318 h-1 and part of the 4-nitrophenol-N was used as the nitrogen source (32% N in biomass and 68% N in nitrite). The yield coefficients of strain PNP1 were smaller in ammonium-free than in ammonium-containing medium (e.g. with 4-nitrophenol YX/S = 0.305 g/g compared to 0.350 g/g), which can be explained by the energy expense for the assimilatory nitrite reduction in the biosynthesis of N-containing cellular compounds. But the oxygen consumption was only slightly influenced by the ammonium content of the cultivation medium (e.g. with 4-nitrophenol YO/S = 1.005 g/g compared to 0.954 g/g).
    Additional Material: 5 Ill.
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  • 41
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: No Abstracts.
    Type of Medium: Electronic Resource
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  • 42
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: No Abstracts.
    Type of Medium: Electronic Resource
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  • 43
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: No Abstracts.
    Type of Medium: Electronic Resource
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  • 44
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    Berlin : Wiley-Blackwell
    Acta Biotechnologica 18 (1998), S. 63-75 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: An enzymic characteristic of Novo dextranase was presented. In addition to a high dextranolytic activity (7,200 U/ml), the crude enzyme also contained small amounts of protease, glucoamylase, polygalacturonase, carboxymethylcellulase, laminarinase and chitinase. A highly purified dextranase was then simply separated from a commercial preparation by column chromatographies on DEAE-Sepharose, CM-Sepharose, and by chromatofocussing on Polybuffer Exchanger PBE-94. The enzyme was recovered with an over 200-fold increase in specific activity and a yield of 84%. The final preparation was homogeneous, as observed during high performance liquid chromatography (HPLC). Size-exclusion HPLC indicated that dextranase had a molecular mass of 35 kDa and its isoelectric point, established by chromatofocussing, was 4.85. Analysis of the dextran break-down products indicated that purified dextranase represents an endolytic mode of action, and isomaltose and isomaltotriose were identified as the main reducing sugars of dextran hydrolysis. The enzyme was then covalently coupled to the silanized porous glass beads modified by glutaraldehyde (Carrier I) or carbodiimide (Carrier II). It was shown that immobilization of dextranase gave optimum pH and temperature ranges from 5.4 to 5.7 and from 50°C to 60°C, respectively. The affinity of the enzyme to the substrate decreased by a factor of more than 13 for dextranase immobilized on Carrier I and increased slightly (about 1.4-times) for the enzyme bound to Carrier II.
    Additional Material: 6 Ill.
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  • 45
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The ability of a mixed natural microbial population, collected in an aerated lagoon treating Fluff pulp effluent and Streptomyces viridosporus strain T7A, to degrade lignosulphonate was evaluated. S. viridosporus growing in a mineral medium containing glycerol (7 g/l) and lignosulphonate (1 g/l) allowed 20% of lignosulphonate to be degraded after 18 days of incubation. A culture of the mixed population on culture medium after S. viridosporus growth was unable to degrade lignosulphonate products. Moreover, antagonism between S. viridosporus and the mixed population or between S. viridosporus and the isolated strains from this population was observed. The enhancement of lignosulphonate biodegradation by naturally occurring microorganisms in association with S. viridosporus (bioaugmentation strategy) seems to be difficult.
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  • 46
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 18 (1998) 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 47
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: No Abstracts.
    Type of Medium: Electronic Resource
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  • 48
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    Berlin : Wiley-Blackwell
    Acta Biotechnologica 18 (1998), S. 109-122 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: In fixed-bed bioreactors, the influence of the oxygen content in the inlet air on the biodegradation of diesel fuel in unsaturated soil/compost mixtures was analyzed at 30°C over a period of 7 weeks. Firstly, a wide range from 0 to 80 vol.% O2 was investigated. Subsequently, the range below 5 vol.% O2 was examined more closely. Over the whole test period of seven weeks, no significant influence of oxygen could be observed above 1 vol. % O2 in the inlet air - either on the decrease of the total contaminants or on the total mineralization. Anaerobic conditions should be avoided for the degradation of diesel fuel. During the test period, the courses of CO2 production varied significantly depending on oxygen supply. Furthermore, a model was developed to estimate the total mineralization as a function of oxygen supply. More investigations are recommended in order to test this model for practical application.
    Additional Material: 5 Ill.
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  • 49
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: No Abstracts.
    Type of Medium: Electronic Resource
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  • 50
    Electronic Resource
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    Berlin : Wiley-Blackwell
    Acta Biotechnologica 18 (1998), S. 135-146 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The formation of reactive groups on polyamide nets (nylon 6) and the subsequent immobilization of glucoamylase were investigated. Different mesh sizes of the nets and two chemical methods of enzyme coupling - i( partial hydrolysis of the polyamide with subsequent glutaraldehyde binding and ii) O-alkylation of the carrier using a treatment with a benzene-methyl sulphate mixture - were used. The reactivity of immobilized glucoamylase (GA) was tested by hydrolysis reactions using 1% starch solutions. The highest reactivity (140 μg glc/)min × cm2 was obtained for methylated nylon samples attached to a glass rod and by coupling glucoamylase on the nylon surface which had been treated with lysine and glutaraldehyde. This method resulted in a more reactive and more stable preparation of immobilized glucoamylase as compared to a simpler method of coupling glutaraldehyde to partially hydrolyzed nylon.
    Additional Material: 8 Ill.
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  • 51
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    Berlin : Wiley-Blackwell
    Acta Biotechnologica 18 (1998), S. 148-148 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: No Abstracts.
    Type of Medium: Electronic Resource
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  • 52
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: No Abstracts.
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  • 53
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    Berlin : Wiley-Blackwell
    Acta Biotechnologica 18 (1998) 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 54
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: No Abstracts.
    Type of Medium: Electronic Resource
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  • 55
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The cleaning of the exhaust gases of a bioreactor containing volatile hydrocarbons in a bioreactor system with a closed gas circuit is described. The bioreactor system consisted of three different reactor types: a stirred tank which was filled with hydrocarbon-containing waste water to simulate the exhaust gases of a remediation process; a trickle-bed reactor for aerobic treatment of the exhaust gas from the stirred tank; and a photoreactor containing an algae culture which assimilated CO2 from the trickle-bed reactor and also produced O2. With this bioreactor system, it was possible to efficiently remove volatile organic compounds (VOC) from the waste gases. Depending on the type of waste water investigated, elimination rates of 41% to 93% of BTEX (benzene, ethylbenzene, toluene, xylene) and 29% to 53% of VCH (volatile chlorinated hydrocarbons) were obtained. Due to the photosynthesis of the algae in the system's photoreactor, oxygen concentrations between 12% and 18% [v/v], equivalent to about 57% to 83% DOT, were obtained. This concentration permitted the aerobic degradation to be carried out without having to add fresh air. The trickle-bed reactor and the photoreactor worked continuously, whereas the waste water in the stirred bioreactor was replaced in different batches. The accumulation of toxic compounds in the nutrient solutions of the trickle-bed (EC-50 〉 30 g/l) and of the photoreactor (EC-50 〉 35 g/l) was low. Carbon dioxide concentrations in the gas flow were higher than in fresh air (1% to 3% [vol/vol]), but no long-term accumulation of CO2 occurred. This means that the algae in the photoreactor were active enough to assimilate the CO2 which had been produced. They were also able to produce sufficient oxygen for aerobic hydrocarbon degradation. The system described is a first step towards treating waste gases which results from the bioremediation of hydrocarbon-contaminated media in a closed gas circuit without any emission (e.g. VOC, CO2, germs).
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  • 56
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    Berlin : Wiley-Blackwell
    Acta Biotechnologica 18 (1998), S. 325-326 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: No Abstracts.
    Type of Medium: Electronic Resource
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  • 57
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: No Abstracts.
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  • 58
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    Berlin : Wiley-Blackwell
    Acta Biotechnologica 18 (1998), S. 353-359 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Protoplasts of a xylose-fermenting yeast strain (a fusion product of Pachysolen tannophilus and Saccharomyces cerevisiae) were fused with isolated nuclei of the xylan degrading filamentous fungus Fusarium moniliforme. Polyethyleneglycol 4000 was used as the fusogenic agent. Fourteen stable hybrids showing xylanase activity were obtained. It can be assumed that this ability was acquired from the nuclear genome of the fungus, since the parental yeast strain did not show any xylanase activity. The enzymatic activity was determined quantitatively. The parental strain of the fungus reached its maximum xylanase activity of 796 nkat/ml at 96 h of growth. Four of the hybrids had a xylanase activity of between 211 and 297 nkat/l at 24 h of growth. Zymograms of these hybrids showed the presence of xylanases when grown on xylan as the sole carbon source. Using pulse field electrophoresis gels, no difference between the chromosome pattern of the fusion products and the parental yeast strain was observed.
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  • 59
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    Berlin : Wiley-Blackwell
    Acta Biotechnologica 18 (1998), S. 367-367 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: No Abstracts.
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  • 60
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    Berlin : Wiley-Blackwell
    Acta Biotechnologica 18 (1998), S. 361-366 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The calluses of two hydroxyproline-resistant lines (D20-1 and D30-1) of Solanum tuberosum L. were transferred to a solidified MS medium containing 1.0 mg/I IAA, 2.0 mg/l zeatin, 40.0 mg/l adenine sulphate, 1 g/l casein hydrolysate, 20 g/l sucrose and 10 g/l agar for plant regeneration. The shoot regeneration was only achieved from the callus of line D20-1. Regenerated shoots exhibited morphological variability. The degrees of frost tolerance were higher in the leaves of the regenerated plants compared with the leaves of the non-selected control plants, but lower than that of the callus from which they were regenerated.
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  • 61
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    Journal of Supramolecular Structure 11 (1979), S. 251-258 
    ISSN: 0091-7419
    Keywords: tumorigenicity ; cyclic AMP-dependent protein kinase ; tyrosinase MSH-growth-resistant variant ; mouse melanoma ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: A variant of B-16 F1 mouse melanoma was selected for its ability to survive and replicate in the presence of melanocyte-stimulating hormone (MSH). Although the variant (MR-4) was completely resistant to growth inhibition by MSH, cyclic AMP was still able to block cell replication. Tyrosinase activity in MR-4 cells was considerably lower than in B-16 F1 cells. MSH induced a twofold to three-fold increase in tyrosinase activity in both cell types, but the absolute activity in MR-4 remained significantly less than in the parental cells. MR-4 cells were also found to have a markedly depressed cyclic AMP-dependent protein kinase activity relative to B-16 F1 cells. The protein kinase from both cell types was stimulated by cyclic AMP, but the level of MR-4 kinase activity at maximal cyclic AMP concentrations remained considerably lower than B-16 F1 kinase activity under the same conditions. In both cell types adenylate cyclase activity was markedly stimulated by MSH. When equal numbers of viable F1 and MR-4 cells were injected subcutaneously into C57/B1 mice, the MR-4 cells formed tumors earlier and killed the host sooner than the parental F1 cells. We conclude that the biochemical alteration which allows MR-4 cells to replicate in the presence of MSH is a low level of tyrosinase activity, which in turn may be the result of low cyclic AMP-dependent protein kinase activity.
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  • 62
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    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 11 (1979) 
    ISSN: 0091-7419
    Keywords: Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
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  • 63
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    Journal of Supramolecular Structure 11 (1979), S. 361-370 
    ISSN: 0091-7419
    Keywords: endothelial cells ; platelet-derived growth factor ; thrombin ; wound healing ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Repair of a vascular wound is mediated by migration and subsequent replication of the endothelial cells that form the inner lining of blood vessels. We have measured the growth response of human umbilical vein endothelial cells (HuE) to two polypeptides that are transiently produced in high concentrations at the site of a wound; the platelet-derived growth factor (PDGF) and the protease thrombin. When 104 HuE cells are seeded as a dense island (2-mm diameter) in the center of a 16-mm tissue culture well in medium containing 20% human serum derived from platelet-poor plasma (PDS), no increase in cell number or colony size is observed. With the addition of 0.5 ng/ml partially purified PDGF, colony size increases and the number of cells after 8 days is 4.8 × 104. When human thrombin (1 μg/ml) is added along with the PDGF, the cell number rises to 9.2 × 104. Thrombin alone stimulates no increase in cell number. Although partially purified PDGF stimulates endothelial cells maintained in PDS as well as those maintained in whole blood serum (WBS), pure PDGF is active only when assayed in medium that contains WBS and is supplemented with thrombin. These results suggest the existence of a second class of platelet-derived factors that enable HuE cells to respond to the mitogenic activity of the purified platelet mitogen and thrombin.
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  • 64
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    Journal of Supramolecular Structure 10 (1979), S. 125-135 
    ISSN: 0091-7419
    Keywords: protein phosphorylation ; cAMP-dependent protein kinases ; adenosine on cyclic AMP ; C1300 neuroblastoma ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: DEAE-cellulose chromatography of the 20,000g supernatant fraction of homogenates of C-1300 murine neuroblastoma (clone N2a) yields one major and two minor peaks of cyclic AMP-dependent protein kinase activity. Assessment of the endogenous activation state of the enzyme(s) reveals that the enzyme is fully activated by the treatment of whole cells with adenosine (10 μM) in the presence of the phosphodiesterase inhibitor Ro 20 1724 (0.7 mM). This treatment produces a large elevation in the cyclic AMP content of the cells. The treatment of whole cells with adenosine alone (1-100 μM) or Ro 20 1724 alone (0.1-0.7 mM) produces minimal elevations in cyclic AMP but nevertheless causes significant activations of cyclic AMP-dependent protein kinase. The autophosphorylation of whole homogenates of treated and untreated cells was studied using [γ-32P] ATP, sodium dodecyl sulfate-polyacrylamide gel electrophoresis and autoradiography. Treatments which activate cyclic AMP-dependent protein kinase selectively stimulate the incorporation of 32P into several proteins. This stimulation is most prominent in the 15,000-dalton protein band. The addition of cyclic AMP to phosphorylation reactions containing homogenate of untreated cells stimulates the phosphorylation of the same protein bands. These results indicate that adenosine may have regulatory functions through its effect on the cyclic AMP: cyclic AMP-dependent protein kinase system.
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  • 65
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    Journal of Supramolecular Structure 10 (1979), S. 39-50 
    ISSN: 0091-7419
    Keywords: muscle ; acetylcholine ; acetylcholine receptors ; α-Bungarotoxin ; chick ; modulation ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Acetylcholine receptors were assayed with α-bugarotoxin on embryonic chick skeletal muscle growing in primary cell culture. Toxin was bound specifically to muscle cells and could be competed with D-tubocurarine. Two dissociation constants were obtained by equilibrium binding: 7.2 × 10-9M and 2.7 × 10-7M at 25°C. Two sets of rate constants were also obtained from dissociation kinetics. There are five times more low affinity sites on cells than high affinity sites. The average density of high-affinity receptors is about 200/μm2.A time course of toxin binding to receptors at 37°C vs 25°C in growth medium revealed that under conditions permitting growth and metabolism, toxin bound to cells was lost. The possibility that the growth medium was in-activating toxin molecules was ruled out by showing that unbound toxin molecules in the medium were fully capable of binding to fresh cultures.
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  • 66
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    Journal of Supramolecular Structure 10 (1979), S. 51-60 
    ISSN: 0091-7419
    Keywords: cholera toxin ; GTP ; pigeon erythrocyte ; adenylate cyclase ; cytosolic factor ; phosphodiesterase protein activator ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The activation of adenylate cyclase in lysed pigeon erythrocytes requires, among several cofactors, a nucleotide which may be ATP, GTP, or many other triphosphates. However, after removal of endogenous nucleotides by gel filtration or by adsorption onto charcoal the requirement can be met only by GTP, or an analog of GTP. The GTP is required during the activation of the cyclase by toxin even if GTP is also included during the subsequent adenylate cyclase assay, conducted without toxin. In the presence of GTP it is possible to assay for the cytosolic protein that is also required for the action of cholera toxin. By gel filtration, its apparent molecular weight is 15,000-20,000.
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  • 67
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    Journal of Supramolecular Structure 10 (1979), S. 79-96 
    ISSN: 0091-7419
    Keywords: red cell membrane proteins ; spectrin ; red cell shape ; deformability ; membrane protein cross-linking ; membrane protein disulfide coupling ; red cell adenosine triphosphate ; calcium ; membrane protein polymerization ; discocyte-echinocyte transformation ; irreversibly sickled cells ; sickle cell anemia ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: It has been proposed that the spectrin-actin submembrane network participates in control of red cell shape and deformability. We have examined ATP- and calcium-dependent changes in organization of spectrin in the membrane employing cross-linking of the nearest membrane protein neighbors by spontaneous or catalyzed (CuSO4, O-phenanthroline) intermolecular disulfide couplings and two-dimensional sodium dodecyl sulfate polyacrylamide gel electrophoresis.Cross-linking of fresh red cells resulted in the formation of spectrin and actin dimers and tetramers. ATP-depleted red cells differed from fresh cells in the presence of an additional reducible polymer of MW 〉 1 × 106 selectively enriched in spectrin. This polymer formed spontaneously when red cells were depleted of ATP under aerobic conditions. After anaerobic ATP depletion, the polymer formed in ghosts after cross-linking by catalytic oxidation. Polymerization was prevented by maintenance of ATP and coincided with an ATP-dependent discocyte-echinocyte transformation. This suggests that, in ATP-depleted red cells, spectrin is rearranged to establish closer contacts, and that this may contribute to the discocyte-echinocyte transformation.The introduction of greater than 0.5 mM Ca++ into ghosts by inclusion in hemolysis buffer or into fresh red cells (but not ATP-depleted red cells) by treatment with ionophore A23187 spontaneously produced a nonreducible polymer which others have attributed to transamidative cross-linking of spectrin, band 3, and other proteins. Spontaneous formation of both polymer types (reducible in aerobically ATP-depleted red cells and nonreducible in fresh, Ca++ enriched red cells) resulted in stabilization (“autocatalytic fixation”) of spheroechinocytic shape.Irreversibly sickled cells, which have increased calcium and decreased ATP, and exhibit a permanent membrane deformation, failed to form any of the above polymers. This suggests that in contrast to normal cells depleted of ATP in vitro, fixation of ISC shape in vivo is not related to Ca- and ATP-dependent membrane protein polymerization. However, ISCs had an increased propensity to form the reducible, spectrin-rich polymer during a subsequent metabolic depletion in vitro. This was associated with transformation of ISCs into spheroechinocytes. Similar echinocytic ISCs were found to constitute 5-10% of the densest fractions of freshly separated ISCs. ISCs then exhibit sphero-echniocyte transformation, both in vitro and in vivo. We propose that this is due to spectrin reorganization that presumably results from the progressively increasing calcium and decreasing ATP of ISCs.These data provide evidence of altered spectrin organization in membranes of ATP-depleted, calcium-enriched red cells in vitro and in vivo.
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  • 68
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    Journal of Supramolecular Structure 10 (1979) 
    ISSN: 0091-7419
    Keywords: Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
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  • 69
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    Journal of Supramolecular Structure 10 (1979), S. 227-239 
    ISSN: 0091-7419
    Keywords: spectrin ; actin ; red cell membranes ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The human erythrocyte structural protein spectrin and its subunits I, II were isolated in the presence of Na-dodecyl-sulfate by gel filtration and preparative gel electrophoresis. After removal of the detergent, spectrin alpha-helical content is comparable to spectrin isolated without detergent. Subunits I and II formed single bands in isoelectric focusing (pI = 5.6) and in Ornstein-Davis disc gel electrophoresis systems, indicating the individual subunits are homogenous in nature. The molecular weights of the subunits I and II, determined by Ferguson plot, are 237,500 and 238,600, respectively, which is in good agreement with values obtained by the standard SDS gel relative mobility method. Limited tryptic digestion of spectrin and two-dimensional peptide maps of the individual subunits cleaved by S-cyanylation reaction showed dissimilar patterns, suggesting differences in primary structure between the two subunits.
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  • 70
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    Journal of Supramolecular Structure 10 (1979), S. 265-275 
    ISSN: 0091-7419
    Keywords: membrane hydration ; membrane-bound water ; ANS fluorescence ; infrared spectra ; water-membrane interactions ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Bound water is a major component of biological membranes and is required for the structural stability of the lipid bilayer. It has also been postulated that it is involved in water transport, membrane fusion, and mobility of membrane proteins and lipids. We have measured the fluorescence emission of membrane-bound 1-anilino-8-naphthalenesulfonate (ANS) and the infrared spectra of membranes, both as a function of hydration. ANS fluorescence is sensitive to polarity and fluidity of the membrane-aqueous interface, while infrared absorption is sensitive to the hydrogen bonding and vibrational motion of water and membrane proteins and lipids. The fluorescence results provide evidence of increasing rigidity and/or decreasing polarity of the membrane-aqueous interface with removal of water. The membrane infrared spectra show prominent hydration-dependent changes in a number of bands with possible assignments to cholesterol (vinyl CH bend, OH stretch), protein (amide A, II, V), and bound water (OH stretch). Further characterization of the bound water should allow its incorporation into current models of membrane structure and give insight into the role of membrane hydration in cell surface function.
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  • 71
    ISSN: 0091-7419
    Keywords: protein conformation ; phospholipids ; diglycerides ; lipid fluidity ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: In order to gain direct evidence for lipid-dependent protein conformation in membrane, effects of modification of lipid composition on mobility of spin-labeled cysteine residues were investigated in the plasma membrane of the yeast Saccharomyces cerevisiae. Conversion of the bulk of phospholipids to diglycerides by treatment of the membrane with phospholipase C substantially enhanced spectral anisotropy. However, alteration of the viscosity of the lipid-bilayer by enriching the membrane with palmitelaidic or oleic acid had no effect on mobility of spin-labeled cysteine residues. These observations indicate that while the spin-labeled residues are not in direct contact with the lipid core of the membrane, there are lipid-protein interactions to the extent that removal of polar portion of the bulk of phospholipids induces conformational changes in proteins, which in turn restrict mobility of these residues. It is concluded that conformation of membrane proteins depends on lipid structure and that phospholipids have a role in preserving the native conformation of proteins.
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  • 72
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    Journal of Supramolecular Structure 10 (1979), S. 359-364 
    ISSN: 0091-7419
    Keywords: ribosomes ; crystallization ; hypothermia ; chick embryos ; degeneration ; cell suffering ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The relationship between ribosome crystallization and cell degeneration has been studied in chick embryos at various temperatures, and new methods of inducing ribosome microcrystals are described. A model is discussed that reinterprets the role of low temperatures in these phenomena and provides a unitary explanation of the various cases in which the occurrence of ribosome crystallization in chick embryos has been reported.
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  • 73
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    Journal of Supramolecular Structure 10 (1979), S. 397-404 
    ISSN: 0091-7419
    Keywords: electron microscopy ; hybrid ribosome ; ribosome structure ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Small 40S Artemia salina and large 50S Escherichia coli ribosomal subunits can be assembled into 73S hybrid monosomes active in model assays for protein synthesis. The reciprocal combination-small 30S E coli and large 60S A salina-fails to form hybrids. The 73S hybrid particles strongly resemble homologous 70S E coli and 80S A salina monosomes. The morphologic differences between the corresponding eukaryotic and prokaryotic ribosomal particles, established by electron microscopy, do not significantly affect the assembly and mutual orientation of 40S A salina and 50S E coli subunits in the heterologous monosome. The fact that the structure of the interface, the supposed site of protein synthesis, is preserved in the active hybrid implies that retention or loss of biologic activity of hybrid ribosomes is determined by the extent of conformational changes in the interface.
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  • 74
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    Journal of Supramolecular Structure 10 (1979), S. 433-441 
    ISSN: 0091-7419
    Keywords: macrophage (alveolar) ; plasma membrane ; Ca2+-ATPase reaction ; membrane phosphorylation ; Ca2+ buffering ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: ATPase activity and phosphorylation by [γ-32P] ATP of isolated plasma membrane of alveolar macorphages are stimulated in a parallel fashion by physiologic concentrations of Ca2+, with half-maximal activating effect of this ion at (3-7) × 10-7 M. For various membrane preparations, a direct proportionality exists between Ca2+-dependent ATPase activity and amount of 32P incorporated. Labeling of membrane attains the steady-state level by 10 sec at 0°C, and is rapidly reversed by adenosine diphosphate (ADP). K+ decreases the amount of membrane-bound 32P, mainly by enhancing the rate of dephosphorylation of the 32P-intermediate. Hydroxylamine causes a release of about 90% of 32P bound to the membrane, thus indicating that the 32P-intermediate contains an acyl-phosphate bond. When the labeled plasma membrane is solubilized and electrophoresed on acrylamide gels in the presence of sodium dodecyl sulphate, the radioactivity appears to be largely associated with a single protein fraction of 132,500 ± 2,000 apparent molecular weight. These features of the macrophage Ca2+-ATPase suggest that the enzyme activity might be part of a surface-localized Ca2+-extrusion system, participating in the regulation of Ca2+-dependent activities of the macrophage.
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  • 75
    ISSN: 0091-7419
    Keywords: cell adhesion ; adhesion proteins ; fibronectin ; chondronectin ; collagen substrates ; gangliosides ; cell surface ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Fibronectin mediates the adhesion of fibroblasts to collagen substrates, binding first to the collagen and then to the cells. We report here that the interaction of the cells with the fibronectin-collagen complex is blocked by specific gangliosides, GD1 a and GT1, and that the sugar moieties of these gangliosides contain the inhibitory activity. The gangliosides act by binding to fibronectin, suggesting that they may be the cell surface receptor for fibronectin. Evidence is presented that other adhesion proteins or mechanisms of attachment exist for chondrocytes, epidermal cells, and transformed tumorigenic cells, since adhesion of these cells is not stimulated by fibronectin. Chondrocytes adhere via a serum factor that is more temperature-sensitive and less basic than fibronectin. Unlike that of fibroblasts chondrocyte adhesion is stimulated by low levels of gangliosides. Epidermal cells adhere preferentially to type IV (basement membrane) collagen but at a much slower rate than fibroblasts or chondrocytes. This suggests that these epidermal cells synthesize their own specific adhesion factor. Metastatic cells cultured from the T241 fibrosarcoma adhere rapidly to type IV collagen in the absence of fibronectin and do not synthesize significant amounts of collagen or fibronectin. Their growth, in contrast to that of normal fibroblasts, is unaffected by a specific inhibitor of collagen synthesis. These data indicate the importance of specific collagens and adhesion proteins in the adhesion of certain cells and suggest that a reduction in the synthesis of collagen and of fibronectin is related to some of the abnormalities observed in transformed cells.
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  • 76
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    Journal of Supramolecular Structure 11 (1979), S. 117-122 
    ISSN: 0091-7419
    Keywords: dynein ATPase ; latency ; high-affinity binding site ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The enhancing effect of low concentrations (eg, 8 μM) of bis(4-fluoro-3-nitrophenyl)sulfone (FNS) on 30S dynein ATPase activity is increased when 1 mM dithiothreitol (DTT) is present. The effect of FNS + DTT is optimal at pH 7.5. Activation of the latent ATPase activity of 30S dynein by FNS + DTT is partially prevented by 1-3 μM ATP. Adenylylimidodiphosphate (AMP-PNP) is less effective than ATP, while β,γ-methylene-adenosine triphosphate (AMP-PCP), though a much stronger inhibitor of ATPase activity than AMP-PNP, does not protect against enhancement. These results demonstrate the presence of a high-affinity ATP-binding site on 30S dynein.
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  • 77
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    Journal of Supramolecular Structure 11 (1979) 
    ISSN: 0091-7419
    Keywords: Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
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  • 78
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    Journal of Supramolecular Structure 11 (1979), S. 539-546 
    ISSN: 0091-7419
    Keywords: SV40 transformation ; tumorigenicity ; anchorage independence ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: A syndrome of in vitro properties correlates with the tumorigenicity of SV40-transformed rodent cells. These properties are plasminogen activator production, loss of large actin cables, and anchorage-independent growth. An established rat fibroblast line, its SV40 transformant, several T-antigen negative revertants, and a spontaneous retransformant isolated form one of the revertants were analyzed in vivo for their tumorigenicity and in vitro for the syndrome. The two transformed lines were highly tumorigenic, and had clearly abnormal in vitro properties. The parental rat line was weakly tumorigenic in nude mice and demonstrated a slightly transformed response in the in vitro assays. The revertants were completely nontumorigenic. Expression of the in vitro syndrome was not uniform for all revertants; however, most cell lines maintained the correlation of the syndrome and tumorigenicity.
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  • 79
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    Journal of Supramolecular Structure 11 (1979), S. 563-577 
    ISSN: 0091-7419
    Keywords: plasma membrane ; lectin receptors ; affinity chromatography ; membrane proteins ; hybridoma ; monoclonal antibody ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Concanavalin A-binding (Con A)-binding cell surface glycoproteins were isolated, via Con A-affinity chromatography, from Triton X-100-solubilized Chinese hamster ovary (CHO) cell plasma membranes. The Con A binding glycoproteins isolated in this manner displayed a significantly different profile on sodium dodecyl sulfate-polyacrylamide gels than did the Tritonsoluble surface components, which were not retarded by the Con A-Sepharose column. [125I]-Con A overlays of the pooled column fractions displayed on sodium dodecyl sulfate-polyacrylamide gel electro-phoresis (SDS-PAGE) demonstrated that there were virtually no Con A receptors associated with the unretarded peak released by the Con A-Sepharose column, whereas the material which was bound and specifically eluted from the Con A-Sepharose column with the sugar hapten α-methyl-D-mannopyranoside contained at least 15 prominent bands which bound [125I]-Con A.In order to produce monoclonal antibodies against various cell surface Con A receptors, Balb/c mice were immunized with the pooled Con A receptor fraction. Following immunization spleens were excised from the animals and single spleen cell suspensions were fused with mouse myeloma P3/X63-Ag8 cells. Numerous hybridoma clones were subsequently picked on the basis of their ability to secrete antibody which could bind to both live and glutaraldehyde-fixed CHO cells as well as to the Triton-soluble fraction isolated from the CHO plasma membrane fraction. Antibody from two of these clones was able to precipitate a single [125I]-labeled CHO surface component of ∼265,000 daltons.
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  • 80
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    Journal of Supramolecular Structure 12 (1979), S. 35-46 
    ISSN: 0091-7419
    Keywords: MuLV ; uninfectious particles ; interferon ; virus assembly ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Interferon treatment of JLSV-6 cells chronically infected with Rauscher MuLV leads to the formation of noninfectious particles (interferon virions) containing the structural proteins of env and gag genes as well as additional viral polypeptides. In the control virions the major glycoprotein detected is gp71, interferon virions contain in addition to gp71 and 85k dalton (gp85) glucosamine-containing, fucose-deficient glycoprotein which is recognized by antiserum to MuLV but not by the gp71 antiserum. The surface iodination of the intact virions indicates that both gp71 and gp85 are the major components of the external virions envelope. However, unlike the control virions in which gp71 associates with p15E (gp90), the gp71-p15E complex was not detected in interferon virions. The analysis of the iodinated proteins of the disrupted interferon virions revealed the presence of 85k and 65k dalton polypeptides preciptable with antiserum against MuLV, which are not present in the control virions. The difference in the polypeptide pattern of virions produced in the presence of interferon does not seem to be a consequence of the slowdown in the synthesis of viral proteins or their processing in the interferon-treated cells. Both the structural proteins of env and gag genes seem to be synthesized and processed at a comparable rate in the interferon-treated and -untreated cells. These results indicate an alteration of virus assembly in the presence of interferon.
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  • 81
    ISSN: 0091-7419
    Keywords: fibronectin ; CSP-60 ; extracellular matrix ; thrombogenic properties ; low-density lipoprotein ; receptor redistribution ; asymmetry of cell surfaces ; cell morphology ; spatial configuration ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Vascular endothelial cells cultured in the presence of fibroblast growth factor (FGF) devide actively when seeded at low or clonal cell densities and upon reachin confluence adopt a morphologic appearance and differentiated properties similar to those of the vascular endothelium in vovi. In this review, we present some of our recent observations regarding the characteristics (both structural and functional) of these endothelial cells and the role of FGF in controlling their proliferation and normal differentation. At confluence the endothelial cells from a monolayer of closely apposed and nondividing cell that have a nonthrombogenic apical surface and can no longer internalize bound ligands such as low-density lipoprotein (LDL). The adoption of these properties is correlated and possibly causally related to changes in the cell surface such as the appearance of a 60,000 molecular weight protein (CSP-60); the disappearance of fibronectin from the apical cell surface and its concomitant accumulation in the basal lamina; and a restriction of the lateral mobility of various cell surface receptor sites. In contrast, endothelial cells that are maintained in the absence of FGF undergo within three passages alterations that are incompatible with their in vivo morphologic apperarance and physiologic beharior. They grow at confluence on top of each other and hence can no longer adopt both the structural (CSP-60, cell surface polarity) and functional (barrier function, nonthrombogenicity) attributes of differentiated endothelial cell. Since these characteristics can be reacquired in response to readdition of FGF, in addition to being a mitogen FGF may also be involved in controlling the differentitation and phenotypic expression of the vascular endothelium.
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  • 82
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    Journal of Supramolecular Structure 11 (1979), S. 33-49 
    ISSN: 0091-7419
    Keywords: cell enucleation ; cell reconstruction ; nuclear control of tumorigenicity ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The techniques of somatic cell hybridization have provided a valuable means of studying mechanisms of regulation of mammalian cell differentiation and transformation. Most previous studies have indicated that fusions between tumorigenic and nontumorigenic cells result in hybrid cells that are usually tumorigenic. In recent years it has been demonstrated that the phenotypic expression of tumorigenicity is at least partially due to the extensive chromosome loss that occurs in most interspecific and some intraspecific hybrid cells. In the present study we have utilized enucleation techniques that permit cells to be divided into nuclear (karyoplast) and cytoplasmic (cytoplast) cell fragments. Even though these nuclear and cytoplasmic fragments are metabolically stable for short periods of time, in our hands they ultimately degenerate. Viable cells can be reconstructed by PEG-induced fusion of karyoplasts to cytoplasts. Since reconstructed cells apparently do not segregate chromosomes, they may provide a clearer understanding of the interactions between the nucleus and the cytoplasm in the control of the expression of tumorigenicity. We have reconstructed cells using karyoplasts from the tumorigenic Y-1 cell line and cytoplasts from a nontumorigenic cell line, A-MT-BU-A1. In addition we have reconstructed cells containing Y-1 cytoplasts and A-MT-BU-A1 karyoplasts. The reconstructed cells porduced were assayed for tumorigenicity by their ability to grow in soft agar and in nude mice. The results of these experiments indicate that the reconstructed cells containing a tumorigenic nucleus and a nontumorigenic cytoplasm ultimately are tumorigenic and conversely the reconstructed cells containing a nontumorigenic nucleus and a tumorigenic cytoplasm are nontumorigenic. These experiments support the concept that with these cell lines the nucleus (karyoplast) is sufficient to control the phenotypic expression of tumorigenicity.
    Additional Material: 18 Ill.
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  • 83
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    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 11 (1979) 
    ISSN: 0091-7419
    Keywords: Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Type of Medium: Electronic Resource
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  • 84
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    Journal of Supramolecular Structure 11 (1979), S. 123-138 
    ISSN: 0091-7419
    Keywords: pea stem membranes ; L-cell membranes ; polyisoprenyl oligosaccharides ; glycoprotein synthesis ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Membrane preparations from growing regions of pea stems and activelydividing mouse L-cells form lipid-linked saccharides from GDP-mannose and UDP-N-acetylglucosamine. These lipids have properties which are consistent with those of mono-and di-phosphoryl polyisoprenyl derivatives.In experiments using plant membranes, the monophosphoryl derivative labeled with GDP-(14C) mannose contains mannose only, while the diphosphoryl derivative labeled with the same nucleotide sugar is heterogeneous, containing oligosaccharides corresponding to mannosaccharides of 5, 7, and 9-12 residues. Only the diphosphoryl polyisoprenyl derivatives are labeled with UDP-(14C)glucosamine and these contain predominantly chitobiose and N-acetylglucosamine itself. Unlabeled GDP-mannose added after UDP-N-acetyl (14C)glucosamine results in the formation of higher lipid-linked oligosaccharides which are apparently the same as those which are labeled with GDP-(14C)mannose alone. Incubation of the membranes with GDP-(14C)mannose in the presence of Mn2+, unlabeled UDP-glucose or unlabeled UDP-N-acetylglucosamine results in marked changes in the accumulation of both the polyisoprenyl monophosphoryl mannose and polyisoprenyl diphosphoryl oligosaccharides.Animal cell membranes synthesise lipid-linked oligosaccharides when incubated with UDP-N-acetylglucosamine and GDP-mannose. These oligosaccharides are similar in size to those synthesised by the plant membranes but their formation is more efficient. The potential roles of these compounds in glycoprotein biosynthesis in both plant and animal tissues is discussed.
    Additional Material: 8 Ill.
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  • 85
    ISSN: 0091-7419
    Keywords: cellular adhesion ; platelets ; fibronectin ; hemostasis ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Platelets are cells which develop adhesive properties following stimulation. Since fibronectin (fn) mediates adhesive properties of several cells, we sought evidence for platelet associated fn. Lysates of suspensions of washed human platelets containing ≤50 ng soluble fn/109 cells contained 2.85 μg fn antigen per 109 cells. The platelet fn antigen competition curve showed a similar slope to the curve for purified plasma fn suggesting antigenic identity. Immunofluorescent staining for fn was minimal in intact cells suggesting that the majority of fn antigen is intracellular. In permeable platelets, fluorescent staining for fn was seen in a punctate distribution suggesting a granule localization. Stimulation of platelet secretion by thrombin released platelet fn antigen. Suramin, a drug which inhibits platelet secretion, inhibited fn release. The apparent secretion of platelet fn, taken with the immunofluorescent data, support the localization of a portion of platelet fn antigen in a storage granule.
    Additional Material: 3 Ill.
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  • 86
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    Journal of Supramolecular Structure 11 (1979), S. 175-187 
    ISSN: 0091-7419
    Keywords: growth control ; 3T3 cells ; Schwann cells ; neurites ; plasma membranes ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Control of cell growth by cell to cell contact is reviewed with particular emphasis on two systems - contact inhibition of growth observed with Swiss 3T3 cells and the mitogenic stimulation of Schwann cells by dorsal root ganglia neurites. In both cases the biological effect can be reproduced by the addition of surface membranes to the corresponding cells. In the case of contact inhibition of 3T3 cells, biological activity appears to correlate with membrane binding to the cells. An octylglucoside extract of 3T3 plasma membranes retains the biological activity (growth inhibition) of the original membranes.
    Additional Material: 7 Ill.
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  • 87
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    Journal of Supramolecular Structure 11 (1979), S. 259-267 
    ISSN: 0091-7419
    Keywords: cell surface receptors ; proteolysis of receptors ; positive or negative regulation ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Addition of highly purified thrombin t o cultures of several kinds of nondividing fibroblasts brings about cell division. This stimulation occurs in serum-free medium, permitting studies on its mechanism under chemically defined conditions. Previous studies have shown that action of thrombin a t the cell surface is sufficient to cause cell division and that the proteolytic activity of thrombin is required for its mitogenic effect. These results prompted experiments which showed that there is a cell surface receptor for thrombin and that thrombin must hind to its receptor and cleave it to stimulate cell division. Some of the thrombin that hinds to its receptors becomes attached to them by a linkage that appears to be covalent. However, it is presently unknown whether this direct thrombin receptor complex plays a role in the stimulation.These results raise a number of question that should be explored in future studies. They also provide a foundation on which to build hypotheses about tentative molecular mechanisms that might be involved in the stimulation. Knowledge that thrombin must cleave its receptor to bring about cell division suggests two alternative mechanisms for stimulation by proteolysis. In one the receptor is a negative effector which prevents cell division when it is intact, but not after it has been cleaved. Alternatively, a fragment of the receptor could be a positive effector. In this mechanism, proteolysis by thrombin would produce a specific receptor fragment which brings about cell proliferation. If every protease which cleaves the receptor also stimulates cell division, the receptor is probably a negative effector. In contrast, if certain proteases cleave the receptor but do not stimulate the cells, a fragment of the receptor is likely a positive effector. With negative regulation by the receptor, the controlling events would occur before proteolysis of it, and it might be possible to find putative regulatory molecules by identification of nearest neighbors of the receptor. This should be possible by using bifunctional crosslinking reagents. If a fragment of the thrombin receptor turns out to be a positive effector, it should be possible to identify and study fragments by analyzing the metabolic fate of the receptor. Techniques are now available for this kind of analysis and it should also be possible to determine whether receptor fragments remain in the membrane or whether they are translocated to specific sites within the cell. A critical question to be asked is which of these events and interactions involving the thrombin receptor are necessary for stimulation of cell division. It now appears that the best way to answer this question is to examine these events in a large number of cloned cell populations that are responsive or unresponsive to the mitogenic action of thrombin. If a thrombin-mediated event occurs in all responsive clones but is altered or absent in sonie unresponsive clones, it is probably necessary for stimulation of cell division.
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  • 88
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    Journal of Supramolecular Structure 11 (1979), S. 295-309 
    ISSN: 0091-7419
    Keywords: threshold effects ; liposomes ; aggregation ; ricin ; concanavalin A ; synthetic glycolipids ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Cholesterol analogs containing sugar residues linked by spacer groups to the cholesterol O can be incorporated into egg yolk lecithin small unilamellar liposomes. The synthetic glycolipid analogs distribute evenly on both sides of the bilayer. These liposomes are aggregated by the appropriate lectin. For example, when the sugar residue is a β-galactoside the liposomes are aggregated by ricin and when it is an α-mannoside they are aggregated by Con A. The lectin-mediated aggregation of these liposomes is reversed by the addition of the appropriate sugar. The rates but not the extents of aggregation of these liposomes are highly sensitive to the amount of glycolipid incorporated. Below approximately 5% glycolipid incorporation the rate of the lectin-mediated aggregation of these liposomes is exceedingly slow, whereas above this level rapid aggregation proceeds. At all concentrations studied the synthetic glycolipids are incorporated in a unimodal fashion so that the observed threshold effects cannot be based on possible differences in the manner in which the glycolipids are incorporated at different concentrations. This conclusion is based on (1) studies with galactose oxidase that show that the percentage of galactose oxidation in a liposome prepared from a galactosyl-containing glycolipid is independent of glycolipid concentration, and (2) studies on the aggregation of liposomes containing mixed glycolipids in which the glycolipids are shown to behave independently. The importance of a critical density of membrane-bound receptors in order for aggregation to occur is discussed.
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  • 89
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    Journal of Supramolecular Structure 11 (1979), S. 311-317 
    ISSN: 0091-7419
    Keywords: dynein ; flagella ; ATPase ; sperm motility ; sea urchin ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: A high-resolution sodium dodecyl sulfate polyacrylamide gel electrophoresis system has been used to show the presence, in both whole sperm and isolated flagellar axonemes, of eight polypeptides migrating in the 300,000-350,000 molecular weight range characteristic of the heavy chains of dynein ATPase. Previously, only five such chains have been discernible. Extraction of isolated axonemes for 10 min at 4°C with a solution containing 0.6 M NaCl, pH 7, releases a mixture of particles that separate, in sucrose density gradient centrifugation, into a major peak, dynein 1 ATPase, sedimenting at 21 S and a minor peak at 12-14S. The polypeptide compositions of these two peaks are different. The dynein 1 peak, which contains most of the protein on the gradient, contains approximately equal quantities of two closely migrating heavy chains, with a small amount of a third, more slowly migrating chain; no other heavy chains appear in this peak. Two groups of smaller polypeptides (three intermediate chains, within the apparent molecular weight range 76,000-122,000 and four newly discovered light chains, within the apparent molecular weight range 14,000-24,000) cosediment with the 21 S peak. The heavy chain composition of the 12-14S peak is more complex, all eight heavy chains occurring in approximately the same ratios as occur in intact axonemes.
    Additional Material: 3 Ill.
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  • 90
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    Journal of Supramolecular Structure 11 (1979), S. 339-347 
    ISSN: 0091-7419
    Keywords: switch hypothesis ; cilia ; motility ; vanadate ; calcium ; dynein ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Lateral (L) cilia of freshwater mussel (Margaritana margaritifera and Elliptio complanatus) gills can be arrested in one of two unique positions. When treated with 12.5 mM CaCl2 and 10-5 M A23187 they arrest in a “hands up” position, ie, pointing frontally. When treated with approximately 10 mM vanadate (V) they arrest in a “hands down” position, ie, pointing abfrontally. L-cilia treated with 12.5 mM CaCl2 and 1 mM NaN3 also arrest in a “hands down” position; substitution of 20 mM KC1 and 1 mM NaN3 causes cilia to move rapidly and simultaneously to a “hands up” position.The observations suggest that there are two switching mechanisms for activation of active sliding in ciliary beat one at the end of the recovery stroke and the other at the end of the effective stroke; the first is inhibited by calcium and the second by vanadate or azide. This is consistent with a model of ciliary beating where microtubule doublet numbers 1, 2, 3, and 4 are active during the effective stroke while microtubule doublets numbers 6, 7, 8, and 9 are passive, and the converse occurs during the recovery stroke.
    Additional Material: 6 Ill.
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  • 91
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    Journal of Supramolecular Structure 11 (1979), S. 429-444 
    ISSN: 0091-7419
    Keywords: (H++K+)-ATPase ; transport ATPase ; proton transport ; phospholipids ; phospholipase A2 ; CD spectrum ; gastric ATPase ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The phospholipid and fatty acid composition and role of phospholipids in enzyme and transport function of gastric (H++K+)-ATPase vesicles was studied using phospholipase A2 (bee venom). The composition (%) was phosphatidylcholine (PC) 33%; sphingomyelin (sph) 25%; phosphatidylethanolamine (PE) 22%; phosphatidylserine (PS) 11%; and phosphatidylinositol (PI) 8%. The fatty acid composition showed a high degree of unsaturation. In both fresh and lyophilized preparations, even with prolonged incubation, only 50% of phospholipids were hydrolyzed, but the amount of PE and PS disappearing was increased following lyophilization. There was a marked decrease in K+-ATPase activity (75%) but essentially no loss of the associated K+ p-nitrophenyl phosphatase was found. ATPase activity could be largely restored by various phospholipids (PE 〉 PC 〉 PS). There was also an increase in Mg2+-ATPase activity, partially reversed in fresh preparations by the addition of phospholipids (PE 〉 PS 〉 PC). Proton transport activity of the preparation was rapidly inhibited, initially due to a large increase in the HC1 permeability of the preparation. Associated with these enzymatic and functional changes, the ATP-induced conformational changes, as indicated by circular dichroism spectra were inhibited.
    Additional Material: 8 Ill.
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  • 92
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    Journal of Supramolecular Structure 12 (1979), S. 185-194 
    ISSN: 0091-7419
    Keywords: cytochalasin B derivative ; cell motility ; sugar transport ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Cytochalasin B (CB) is a potent inhibitor of sugar transport and cell motility in animal cells. We have synthesized and characterized the CB derivative 7-acetylcytochalasin B (CBAc) and have found that it has differential effects on transport and motile processes in fibroblasts. The derivative inhibited sugar transport in human red cells, 3T3 cells, and chicken embryo fibroblasts at micromolar concentrations, although it was less potent than its parent compound. Unlike CB, which causes fibroblasts to round up and arborize at less than 10 μM, CBAc had no effect on fibroblast morphology and membrane ruffling at concentrations as high as 90 μM. Competitive binding experiments using [3H] CB showed that the affinity of CBAc for sites related to sugar transport in the red cell membrane is about one-fourth of that of CB. In contrast, similar experiments using [3H] dihydrocytochalasin B (a derivative which inhibits cell motility but not sugar transport) showed that the affinity of CBAc for sites associated with red cell spectrin and actin is only about 1/20 of that dihydrocytochalasin B. This study demonstrates that acetylation of the C-7 hydroxyl group of CB reduces its effect on cell morphology and motility much more than its ability to inhibit sugar transport. This observation, together with our earlier work with dihydrocytochalasin B, establishes that the pharmacologic effects of CB on fibroblasts result from the binding of the drug to two distinct classes of receptors and that these receptors interact with different parts of the cytochalasin molecule.
    Additional Material: 6 Ill.
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  • 93
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    Journal of Supramolecular Structure 12 (1979), S. 273-291 
    ISSN: 0091-7419
    Keywords: cholera toxin-receptors ; cell growth ; glycolipids-transformation ; organization in membranes ; glycolipids as cell surface receptors ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Cholera toxin receptors have been isolated from both a mouse fibroblast (Balbc/3T3) and mouse lymphoid cell line labeled by the galactose oxidase borotritiide technique. Tritiated receptor-toxin complexes solubilized in NP40 were isolated by addition of toxin antibody followed by a protein A-containing strain of Staphylococcus aureus. In both cell types by far the major species of toxin receptor isolated was ganglioside in nature, although galactoproteins were also present in the immune complexes. Whether the galactoproteins form part of a toxin-receptor complex or are artifacts of the isolation procedure is presently unclear.The relative specificity of cholera toxin for a carbohydrate sequence in a glycolipid suggests that the toxin might prove a useful tool in establishing the function and organization of glycolipids in membranes. For example, interaction of cholera toxin with the mouse lymphoid cell line was shown to result in patching and capping of bound toxin, raising the possibility that the glycolipid receptor interacts indirectly with cytoskeletal elements. Cholera toxin might also be used to select for mutant fibroblasts lacking the toxin receptor and therefore having an altered glycolipid profile. Such mutants might prove useful in establishing the relationship (if any) between modified glycolipid pattern and other aspects of the transformed phenotype. Attempts to isolate mutants, based on the expectation that growth of cells containing the toxin receptor would be inhibited by the increase in cAMP levels normally induced by cholera toxin, proved unsuccessful. Cholera toxin failed to inhibit significantly the growth of either Balbc or Swiss 3T3 mouse fibroblasts although it markedly elevated cAMP levels.
    Additional Material: 11 Ill.
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  • 94
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    Journal of Supramolecular Structure 10 (1979), S. 443-455 
    ISSN: 0091-7419
    Keywords: ribosomes, 30S subunit structure, immunochemistry ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Antibodies to Escherichia coli ribosomal protein S4 react with S4 in subribosomal particles, eg, the complex of 16S RNA with S4, S7, S8, S15, S16, S17, and S19 and the RI* reconstitution intermediate, but they do not react with intact 30S subunits. Antibodies were isolated by three different methods from antisera obtained during the immunization of eight rabbits. Some of these antibody preparations, which contained contaminant antibodies directed against other ribosomal proteins, reacted with subunits, but this reaction was not affected by removal of the anti-S4 antibody population. Other antibody preparations did not react with subunits. It is concluded that the antigenic determinants of S4 are accessible in some protein deficient subribosomal particles but not in intact 30S subunits.
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  • 95
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    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 11 (1979) 
    ISSN: 0091-7419
    Keywords: Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
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  • 96
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    Journal of Supramolecular Structure 12 (1979), S. 245-257 
    ISSN: 0091-7419
    Keywords: thrombin receptors ; epidermal growth factor receptors ; cell proliferation ; normal and transformed cells ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: When 125I-thrombin was incubated with foreskin fibroblasts, cervical carcinoma cells or fibrosarcoma cells of human origin, or with secondary chick embryo cells or Chinese hamster lung cells, it became directly linked to its cell surface receptors. The thrombin-receptor complex (TH-R) was derived exclusively from a pool of 125I-thrombin that had become specifically bound to the cell surface. The linkage was probably covalent, since the complex was resistant to boiling in sodium dodecyl sulfate and 2-mercaptoethanol. Raising the pH to 12 disrupted TH-R, but did not affect a similar complex between epidermal growth factor and its receptor, suggesting that the linkage of these mitogens to their receptors was different. Mild trypsin treatment removed the ability of cells to form TH-R; however, after a 24-h incubation in serum-free medium, trypsin-treated cells recovered the capacity to form TH-R, suggesting that TH-R resulted from interaction of 125I-thrombin with a cellular rather than a serum component. The mitogenic response of cells to thrombin was inversely related to the fraction of specifically bound 125I-thrombin represented by TH-R. The role of TH-R in mitogenesis may be clarified in future studies by obtaining clones of Chinese hamster lung cells that vary in their capacities to form TH-R and to respond to the mitogenic action of thrombin.
    Additional Material: 6 Ill.
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  • 97
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    Journal of Supramolecular Structure 10 (1979), S. 1-11 
    ISSN: 0091-7419
    Keywords: virus assembly ; limited proteolysis ; conformational change ; cooperativity ; electron microscopy ; optical diffraction ; computer image processing ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Giant T4 phage capsoids formed in canavanine-treated cultures infected by phage mutants in genes 21 and 17, respectively, differ with regard to cleavage of the major capsid protein, gp 23, and in the fine structure of their hexagonal surface lattices. Quantitative computer processing of electron micrographs shows that the significant differences in capsomer morphology amount to six symmetrically placed features present in the uncleaved hexamer but absent after cleavage. These features may be related with the N-terminal portions of gp 23 monomers excised by phage-specific proteolysis. Cleaved 17- giants can be induced to undergo a further structural transformation (expansion). Structural characteristics of partially transformed giant particles give clues about the dynamics of the cleavage and expansion transformations. Both processes appear to be polar, initiating in one cap and propagating along the particle. The transition zone of partial cleavage is diffuse, whereas the transition between unexpanded and expanded areas is confined to a narrow band of some 20 nm width.
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  • 98
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    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 10 (1979) 
    ISSN: 0091-7419
    Keywords: Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
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  • 99
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    Journal of Supramolecular Structure 11 (1979), S. 493-502 
    ISSN: 0091-7419
    Keywords: cell surface ; plasma membrane ; glycoproteins ; affinity chromatography ; lectins ; Novikoff hepatocellular carcinoma ; neuraminidase ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Novikoff hepatocellular carcinoma cells were radioiodinated by a cell surface-specific method using lactoperoxid ase/125I. The iodinated proteins were solubilized in 0.5% Nonidet P-40 and subjected to affinity chromatography on Sepharose-conjugated lectins (Ricinus communis agglutinins I or II, soybean agglutinin, concanavalin A, or wheat germ agglutinin) and analyzed by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. Almost all the iodinated proteins bound to one or more of the Sepharose-conjugated lectins, presumptive evidence that these peptides are glycosylated. Lectin affinity chromatography resolved defined subsets of iodinated glycoproteins and suggested that certain glycoproteins could be fractionated on the basis of heterogeneity of their heterosaccharide moieties. Incubation of the iodinated cells with neuraminidase resulted in increased binding of iodinated proteins to Sepharose-conjugated Ricinus communis agglutinins I and II and soybean agglutinin and decreased binding to Sepharose-conjugated wheat germ agglutinin. Binding of iodinated proteins to concanavalin A was unaffected by neuraminidase treatment of the cells. These studies demonstrate the utility of lectins for the multicomponent analysis of plasma membrane proteins.
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  • 100
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    Journal of Supramolecular Structure 10 (1979), S. 165-174 
    ISSN: 0091-7419
    Keywords: glucocorticoids ; calcium ; thymus ; lymphosarcoma ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: We have examined the possibility that hormone-induced increases in calcium uptake might initiate the lethal actions of glucocorticoids in two types of lymphoid cells. Hormone-induced increases in nuclear fragility are used as the measure of hormone action, since in both rat thymus cells and in mouse P1 798 lymphosarcoma cells increased nuclear fragility (the inability of nuclei to survive lysis of the cells by hypotonic shock) precedes other indices of cellular deterioration by several hours.In the case of the tumor cells, those from corticosteroid-sensitive lines are less able to withstand incubation in vitro than resistant cells. Such differences in cell survival are predicted both by earlier changes in nuclear fragility and also by differences in calcium uptake. However, there is no detectable early glucocorticoid effect on calcium uptake that precedes or coincides with the substantial hormone-induced increases in nuclear fragility that develop in the sensitive cells by 2 h.In rat thymus cells the absence of calcium in the medium does prevent some of the increase in nuclear fragility and cell disintegration that occurs spontaneously during incubation in vitro. Nevertheless, when cells are exposed to hormones the glucocorticoid effect on nuclear fragility develops in the absence of calcium and is similar in magnitude to that seen in the presence of calcium.We conclude that calcium seems to enhance the spontaneous deterioration of lymphoid cells, and there is a large increase in calcium uptake that occurs as cells deteriorate. It nevertheless seems unlikely that hormone-induced changes in calcium uptake initiate the lethal actions of glucocorticoids. The data also support a proposal made earlier [2] that resistance to glucocorticoids in tumor cells may develop by the selection of cells with hardier membranes.
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