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  • Life and Medical Sciences  (20)
  • Biochemistry and Biotechnology  (10)
  • Wiley-Blackwell  (30)
  • American Institute of Physics
  • 1
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 204 (1990), S. 9-23 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The dorsal vessel (DV) in the abdomen of the blood-feeding insect Rhodnius prolixus was divided functionally into two regions, the heart, into which haemolymph entered the DV through four pairs of ostia located in abdominal segment VII, and the aorta, along which the haemolymph was propelled from abdominal segment VI to the thorax. Osmium-fixed whole mounts revealed the DV to consist of spirally arranged striated muscle fibers and to possess two rows of ventrally attached longitudinal fibers extending the length of the abdomen. Seven pairs of alary muscles were found attached to the DV in the posterior abdominal segments. Contractions of the alary muscles attached to the ventral surface of abdominal segments VII and VIII served to expand the heart. Electron microscopy revealed the DV to consist of a thin layer of contractile elements surrounded by an inner (intima) and outer (adventitia) connective tissue layer. Embedded in the intima along each lateral side of the DV were two large groups of endocardial cells extending the length of the DV. A small group of pericardial cells was embedded in the adventitia along the mid-ventral side of the DV, and clusters of pericardial cells were found attached to the alary muscles. Nerve terminals were found only on the heart: they contained agranular synaptic vesicles approximately 30 nm in diameter and densely stained granules approximately 100-120 nm in diameter. These structural components are discussed in relation to the role of the DV in circulation.
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  • 2
    ISSN: 0730-2312
    Keywords: taxol ; microtubules ; vimentin ; intermediate filaments ; protein phosphorylation ; protein kinases ; inhibitors ; cytoskeleton ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Taxol, a microtubule stabilizing agent, has been extensively investigated for its antitumor activity. The cytotoxic effect of taxol is generally attributed to its antimicrotubule activity and is believed to be cell cycle dependent. Herein, we report that taxol induces hyperphosphorylation and reorganization of the vimentin intermediate filament in 9L rat brain tumor cells, in concentration- and time-dependent manner. Phosphorylation of vimentin was maximum at 10-6 M of taxol treatment for 8 h and diminished at higher (10-5 M) concentration. Enhanced phosphorylation of vimentin was detectable at 2 h treatment with 10-6 M taxol and was maximum after 12 h of treatment. Taxol-induced phosphorylation of vimentin was largely abolished in cells pretreated with staurosporine and bisindolymaleimide but was unaffected by H-89, KT-5926, SB203580, genistein, and olomoucine. Thus, protein kinase C may be involved in this process. Hyperphosphorylation of vimentin was accompanied by rounding up of cells as revealed by scanning electron microscopy. Moreover, there was a concomitant reorganization of the vimentin intermediate filament in the taxol-treated cells, whereas the microtubules and the actin microfilaments were less affected. Taken together, our data demonstrate that taxol induces hyperphosphorylation of vimentin with concomitant reorganization of the vimentin intermediate filament and that this process may be mediated via a protein kinase C signaling pathway. J. Cell Biochem. 68:472-483, 1998. © 1998 Wiley-Liss, Inc.
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  • 3
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Light microscopy (LM) and scanning (SEM) and transmission electron microscopy (TEM) disclose seven types of hemocytes in adults of the German cockroach, Blattella germanica (Dictyoptera: Blattellidae) - namely, prohemocytes (PR), granulocytes (GR), plasmatocytes (PL), spherulocytes (SP), adipohemocytes (AD), coagulocytes (CO), and oenocytoids (OE). Their shape, size, surface appearance, and internal ultrastructure are characterized here. The shapes and relative sizes of hemocytes noted in vitro have been compared with those flowing through the wing veins (in vivo). The GRs constitute more than 90% of the hemocyte population and have roles in the defense system such as encapsulation and phagocytosis. They are characterized by numerous cytoplasmic granules and marginal microtubular bundles, which are commonly noted in the blood cells of both vertebrates and invertebrates, but have been rarely reported in insect hemocytes. The PRs are characterized by being spherical and small, having a relatively large nucleus and a small area of cytoplasm. The polymorphic PLs have some micropapillae on the cell surface and fewer granules than the GRs. The SPs are characterized by an oblate shape, raspberrylike appearance in SEM, and many spherules in the cytoplasm. The ADs are spherical and have large, refringent fat droplets. The COs possess a distinctive cartwheellike appearance when observed by LM but resemble GRs in TEM preparations. The OEs are opaque and often have an eccentric nucleus. Of the seven types of hemocytes, all, except the COs, can be recognized both in vivo and in vitro by LM; the COs can be recognized only in vitro. SEM does not allow the COs to be distinguished from the GRs, except in samples in which coagulation has occurred. All hemocyte types can be recognized by TEM. Thus, all three types of microscopy allow the various types of hemocytes to be recognized; unequivocal discrimination among the cells is best achieved by combining all the three kinds of microscopy.
    Additional Material: 24 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 195 (1988), S. 17-29 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Cobalt applied extracellularly to the cephalic aorta in Rhodnius prolixus filled neurosecretory cells (NSCs) located in the brain, the retrocerebral complex, and the suboesophageal ganglion (SOG). Axons of these cells converged over the corpora cardiaca and corpus allatum and merged into a large tract before travelling posteriorly along the ventral side of the aorta. Cobalt-filled cells in the posterior margins of the brain and the retrocerebral complex lacked extensive dendritic arborizations, suggesting that their cell bodies and/or axonal processes in the retrocerebral complex are directly involved with integrative processes determining hormone release. Cobalt-filled cell bodies in the anterior region of the brain were closely associated with the ocellar nerve, and the cobalt-filled cells in the SOG formed extensive dendritic arborizations in the neuropile, suggesting the involvement of sensory cells in regulation of their electrical activity. The ability to fill NSCs with cobalt applied to the aorta demonstrates that the cephalic aorta of R. prolixus is an important neurohaemal region.
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 35 (1990), S. 976-982 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The concept of pore size distribution is incorporated into the Clark model of enzyme immobilization in the present study. This refined model predicted that in the case of small harmonic pore radius with the same surface area and porosity of the support, more enzyme could be loaded in a support with nonuniform pores than that with uniform pores. In comparing the enzyme loading efficiency of the support with two different pore size distributions, the one with Gaussian distribution had the greater amount of enzyme immobilized than the other one with Rajagopalan's distribution. Furthermore, more enzyme could be loaded in a support with wider Gaussian pore size distribution than that with narrower distribution. The immobilized enzyme profile in the solid support with pore size distribution displayed a stepwise pattern which differed appreciably from the sigmoidal profile predicted for the support with uniform pore size. This stepwise enzyme distribution profile became sigmoidal with decreasing hT or increasing k. The new model could be used for designing protocols for an enzyme immobilization process.
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 19 (1977), S. 143-152 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A rapid chemical procedure based on the solubility of a holocellulose sample in a system of dimethyl sulfoxide with paraformaldehyde has been developed to provide a laboratory method for predicting dry matter digestibility of cellulose containing samples. The amount of dry matter solubilized by the chemical procedure was closely correlated with anaerobic, in vitro, rumen fluid digestion and with digestibility as measured by aerobic Cellulomonas, sp. bacteria. The quantity of solvent and dissolving time had little effect on solubility over a wide range. The method is rapid, well suited for various cellulosic materials, and may be carried out with simple equipment and facilities.
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 25 (1983), S. 363-375 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Schizosaccharomyces pombe was cultivated in a medium of glucose (10 g/L) malt extract (3 g/L), yeast extract (3 g/L), and bactopeptone (5 g/L) to form flocs. More than 95% of the cell population were flocculated. Variation in glucose concentration (from 10 to 100 g/L) did not affect flocculation. Yeast extract helped induce flocculation. Application of the immobilized yeast for the continuous production of ethanol was tested in a column reactor. Soft yeast flocs (50-200 mesh) underwent morphological changes to heavy particles (0.1-0.3 cm diameter) after continuously being fed with fresh substrates in the column. Productivity as high as 87 g EtOH L-1 h-1 was obtained when a 150 g/L glucose medium was fed. The performance of this yeast reactor was stable over a two-month period. The ethanol yield was 97% of the theoretical maximum based upon glucose consumed.
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 38 (1991), S. 761-766 
    ISSN: 0006-3592
    Keywords: biphasic system ; lipase-catalyzed hydrolysis ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A theoretical model for the lipase-catalyzed hydrolysis of high-concentration olive in biphasic isooctane-aqueous systems has been proposed and confirmed by experiments. The enzymatic reaction of the Michaelis-Menten type that occurred at the interface between organic and aqueous phases was assumed in deriving the rate equations, from which the maximum reaction rate could be obtained by carefully adjusting the volume ratio between the two phases to the optimal value. Equilibrium conversions higher than 98% for 0.1 g/L olive oil in isooctane were attained for systems with volume ratios up to one. Fractions of lipase and lipase-substrate complex adsorbed at the interface increased and seemed to approach to asymptotic values asthe rotation speed of impeller increased. Activity of the lipase showed no apparent change between 26 and 37°C, but decrease rapidly with temperature above 43°C. The methodology presented in this work might be used to find kinetic parameters for reactor design and scaleup.
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 38 (1991), S. 206-211 
    ISSN: 0006-3592
    Keywords: reversed micelles ; lipase ; hydrolysis ; competitive product inhibition ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Candida rugosa lipase has been used to investigate the hydrolysis of high concentration olive oil in the AOT-isooctane reversed micellar system at Wo = 10, pH 7.1, and 37°C. Results from this work show the hydrolytic reaction obeys Michaelis-Menten kinetics up to the initial substrate concentration of 1.37M, with turnover number kcat and Michaelis constant KM of 67.1 μmol/min mg enzyme and 0.717M, respectively. A competitive inhibition by the main product, oleic acid, has been found with a dissociation constant KI for the complex EP* of 0.089M. The rate equation was further analyzed in the time course reaction and was found in agreement with the experimental results for lower substrate concentrations, up to 0.341M. Large deviation occurred at high substrate concentrations, which may be due to the effects of large consumption of water on kinetics, on the formation of glycerol, and on the deactivation of lipase in the hydrolysis reaction as well.
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 42 (1993), S. 449-454 
    ISSN: 0006-3592
    Keywords: artificial seed ; sodium alginate ; chitosan ; complex coacervation ; encapsulation ; embryoid viability ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Survival of secondary embryoids of winter oilseed rape (Brassica napus ssp. oleifera cv. Primor) has been used as an assay for the development of artificial seeds involving complex coacervation of alginate (polyanion) with chitosan (polycation). Germination frequency of 100% was achieved for encapsulated embryoids when alginate formed the inner matrix and chitosan the outer layer. When the matrix makeup was reversed, there was no germination of embryoids. The artificial seeds produced were hardened in dilute alkaline solutions of NaOH and Ca(OH)2. An optimum setting time could be selected based on a quantitative measurement of resistance of hardened capsules to compression and the germination frequency of the encapsulated embryoids. © 1993 John Wiley & Sons, Inc.
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