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  • Organic Chemistry  (10)
  • Biochemistry and Biotechnology  (9)
  • Life and Medical Sciences  (9)
  • 1990-1994  (27)
  • 1870-1879  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Production of indole alkaloids by surface immobilized C. roseus cells (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 35 (1990), S. 660-667 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A technique was developed to surface immobilize plant cells and was scaled up in laboratory size bioreactors. This technique was shown not to hinder the biosynthetic potential of Catharanthus roseus immobilized cells and to induce a partial release (300 μg/L) of serpentine into the culture medium contrary to suspension cultured cells. The release pattern seemed to follow the biosynthesis trends of the product. This release mechanism could be stimulated by a factor of 10 within 2 h by increasing the pH of the culture from 5.0 to 5.5.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260350703
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  • 2
    Electronic Resource
    Electronic Resource
    Development of bioreactors for the culture of surface immobilized plant cells (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 35 (1990), S. 702-711 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The scaleup of the technique of plant cell surface immobilization was performed successfully in specifically designed laboratory size bioreactors. The immobilizing matrix was formed into a vertically wound spiral providing for a high immobilizing area-to-volume ratio (0.8-1.2 cm-1). A modified airlift and a mechanically stirred vessel delivered a best bioreactor performance characterized by low biomass frothing and highly efficient plant cell attachment and retention (≥96%). The growth of Catharanthus roseus cells investigated in these bioreactors was found not to be mass transfer limited. It required mild mixing and aeration levels (kLa ∼ 10-15 h-1). The biomass formation pattern of surface immobilized plant cells generally exhibited a linear growth phase followed by a stationary phase characterized by the presence of residual carbohydrates in the medium, contrary to suspension cultures. This behavior was found to depend on the plant cell type and/or line cultured, as well as on the inoculum age. The space restriction and unidirectional growth of the SIPC biofilm combined with the limited availability of essential intracellular nutrients rapidly accumulated from the medium by the stationary phase inoculated plant cells all likely contributed to the culture behavior.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260350707
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  • 3
    Electronic Resource
    Electronic Resource
    Distribution of filamentous actin in and around spermatids and in spermatozoa of Australian conilurine rodents (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 30 (1991), S. 369-384 
    Details
    ISSN: 1040-452X
    Keywords: F-actin ; Sperm head ; Australian rodents ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The distribution of filamentous actin around the maturing sperm head and in spermatozoa of four species of Australian conilurine rodents was investigated at the light and electron microscopic levels. Similar results were obtained for all the species studied. Mechanically isolated spermatids had NBD-phallacidin-positive longitudinal bands of fluorescence over the dorsolateral surface and, in late spermatids, bands of bright fluorescence passed perpendicularly from the dorsal convex to ventral concave surface. TEM observations indicated that these regions corresponded to filaments of ectoplasmic specializations and granular filamentous material around the tubulobulbar complexes, respectively. In testicular and cauda spermatozoa NBD-phallacidin fluorescent material was present in the two ventral processes that extended from the upper concave surface of the sperm head; also fainter material occurred along the concave border and as a dorsocaudal spur. Its distribution was identical for testicular and cauda spermatozoa. TEM of late spermatids showed that in the ventral process closest to the apical hook there were between 170 and 245 filaments, which attached to the inner surface of the postacrosomal dense lamina; in the more caudal ventral process about 70 filaments occurred. No filaments were, however, visible in the mature spermatozoon but, after immunocytochemical labelling for actin, deposition of gold particles was evident over ventral processes of both late spermatids and cauda spermatozoa. Within the female tract these ventral processes made contact with the zona matrix and were taken into the egg cytoplasm unchanged in morphology. The possible functional significance of the filamentous actin in these structures is discussed.
    Additional Material: 39 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1080300412
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  • 4
    Electronic Resource
    Electronic Resource
    Marsupial fertilization: Some further ultrastructural observations on the dasyurid Sminthopsis Crassicaudata (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 32 (1992), S. 277-292 
    Details
    ISSN: 1040-452X
    Keywords: Oocyte maturation ; Sperm - egg interaction ; Sperm incorporation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Various morphological aspects of in vivo egg maturation and sperm - egg interaction were investigated in the Australian marsupial Sminthopsis crassicaudata with the transmission and scanning electron microscopes. Cortical granules invariably occurred in primary oocytes, with the number increasing after resumption of the first meiotic division. They generally occurred close to the oolemma, including the region near the oocyte nucleus. After mating, spermatozoa with intact acrosomes, which had a homogeneous electron-dense matrix, were found on the outer zona surface, but loss of acrosomal contents had occurred by the time of zona penetration. Sperm incorporation into the egg took place at the metaphase II stage of meiosis, and, at this time, cortical granules disappeared from the egg cortex. Sperm heads with condensed chromatin in the egg cytoplasm had an electron-dense layer of subacrosomal material over part of the dorsal nuclear surface, but no membranes were present around these incorporated spermatozoa. Sperm chromatin decondensation resulted in an elevation of egg cytoplasm, and the cell membrane over this area lacked microvilli. The pronuclear envelope was not laid down until after chromatin decondensation had occurred. By this time the fertilized egg had reached the uterus, and a smooth, electron-dense, shell membrane had been deposited. These observations, together with our previous findings, indicate that some of the processes of sperm - egg interaction are similar to those in eutherian mammals, whereas others appear highly divergent.
    Additional Material: 47 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1080320314
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  • 5
    Electronic Resource
    Electronic Resource
    Unusual nuclear structure of the spermatozoon in a marsupial, Sminthopsis crassicaudata (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 37 (1994), S. 78-86 
    Details
    ISSN: 1040-452X
    Keywords: Marsupial ; Sperm head ; Chromatin ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The organization of sperm chromatin in the dasyurid marsupial, Sminthopsis crassicaudata, was investigated using various morphological techniques. Transmission electron microscopy indicates two quite distinct chromatin regions became evident late in spermiogenesis with an outer globular region containing blocks of very electron-dense chromatin. Fluorescent light microscopical studies after staining with DNA dyes and 7-amino actinomycin D of testicular, caput, and cauda epididymal spermatozoa showed that this region fluoresced less brightly than the rest of the nucleus, indicating the presence of fewer DNA binding sites. Freeze fracture showed that the chromatin in most of the nucleus had randomly arranged particles of various sizes, but that of the outer region was composed entirely of small particles. This outer region was more resistant to low concentrations of the ionic detergent, SDS, whereas both guanidine hydrochloride and urea together with sodium chloride generally dispersed all the chromatin except that in the outer globular region and in a localized area of the nucleus beneath the acrosome. This study has thus revealed that the outer globular chromatin of these spermatozoa responds differently to ionic detergents and protein denaturing agents and has a different chromatin organization than most of the rest of the nucleus. The significance of these differences remains, however, to be determined. © 1994 Wiley-Liss, Inc.
    Additional Material: 23 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1080370111
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  • 6
    Electronic Resource
    Electronic Resource
    Morphological changes in the oocyte and its surrounding vestments during in vivo fertilization in the dasyurid marsupial sminthopsis crassicaudata (1990)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 204 (1990), S. 177-196 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This light and transmission electron microscopical study shows that the first polar body is given off before ovulation and that part of its cell membrane and that of the surrounding oocyte have long microvilli at the time of its ejection. Several layers of cumulus cells initially surround the secondary oocyte and first polar body, but the ovulated oocytes in the oviducts in the process of being fertilized do not have cumulus cells around them. Partly expelled second polar bodies occur in the oviduct; they are elongated structures that lack organelles and have electron-dense nuclei. A small fertilization cone appears to form around the sperm tail at the time of sperm entry into the egg and an incorporation cone develops around the sperm head in the egg cytoplasm. In three fertilized eggs a small hole was seen in the zona, which was presumably formed by the spermatozoon during penetration. Cortical granules, present in ovarian oocytes, are not seen in fertilized tubal or uterine eggs; release of their contents probably reduces the chances of polyspermy, although at least one polyspermic fertilized egg was seen and several other fertilized eggs had spermatozoa within the zona pellucida. In the zygote the pronuclei come to lie close together, but there was no evidence of fusion. A “yolk mass,” which becomes eccentric before ovulation, is extruded by the time the two-cell embryos are formed, but many vacuoles remain in the non-yolky pole of the egg. A shell membrane of variable thickness is present around all uterine eggs but its origin remains undetermined.
    Additional Material: 51 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1052040207
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  • 7
    Electronic Resource
    Electronic Resource
    A statistical analysis of the effect of substrate utilization and shear stress on the kinetics of biofilm detachment (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 41 (1993), S. 728-735 
    Details
    ISSN: 0006-3592
    Keywords: biofilm ; shear stress ; substrate loading ; biofilm detachment ; Pseudomonas aeruginosa ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: One of the least understood processes affecting biofilm accumulation is detachment. Detachment is the removal of cells and cell products from an established biofilm and subsequent entrainment in the bulk liquid. The goal of this research was to determine the effects of shear stress and substrate loading rate on the rate of biofilm detachment.Monopopulation Pseudomonas aeruginosa and undefined mixed population biofilms were grown on glucose in a RotoTorque biofilm reactor. Three levels of shear stress and substrate loading rate were used to determine their effects on the rate of detachment. Suspended cell concentrations were monitored to determine detachment rates, while other variables were measured to determine their influence on the detachment rate. Results indicate that detachment rate is directly related to biofilm growth rate and that factors which limit growth rate will also limit detachment rate. No significant influence of shear on detachment rate was observed.A new kinetic expression that incorporates substrate utilization rate, yield, and biofilm thickness was compared to published detachment expressions and gives a better correlation of data obtained both in this research and from previous research projects, for both mono- and mixed-population biofilms. © John Wiley & Sons, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260410707
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  • 8
    Electronic Resource
    Electronic Resource
    Factors affecting microbial sulfate reduction by Desulfovibrio desulfuricans in continuous culture: Limiting nutrients and sulfide concentration (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 40 (1992), S. 725-734 
    Details
    ISSN: 0006-3592
    Keywords: Desulfovibrio desulfuricans ; stoichiomentry ; kinetics ; microbial sulfate reduction ; sulfate limitation ; nitrogen limitation ; sulfide inhibition ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The effects of sulfate and nitrogen concentrations of the rate and stoichiometry of microbial sulfate reduction were investigated for Desulfovibrio desulfuricans grown on lactate and sulfate in a chemostat at pH 7.0. Maximum specific growth rates (μmax), half-saturation coefficients (Ksul), and cell yield (Yc/Lac) of 0.344 ± 0.007 and 0.352 ± 0.003 h -1, 1.8 ± 0.3 and 1.0 ± 0.2 mg/L, and 0.020 ± 0.003 and 0.017 ± 0.003 g cell/g lactate, respectively, were obtained under sulfate-limiting conditions at 35°C and 43°C. Maintenance energy requirements for D. desulfuricans were significant under sulfate-limiting conditions. The extent of extracellular polymeric substance (EPS) produced was related to the carbon: nitrogen ratio in the medium. EPS production rate increased with decreased nitrogen loading rate. Nitrogen starvation also resulted in decreased cell size of D. desulfuricans. The limiting C : N ratio (w/w) for D. desulfuricans was in the range of 45 : 1 to 120 : 1. Effects of sulfide on microbial sulfate reduction, cell size, and biomass production were also ivestigated at pH 7.0. Fifty percent inhibition of lactate utilization occurred at a total sulfide concentration of approximately 500 mg/L. The cell size of D. desulfuricans decreased with increasing total sulfide concentration. Sulfide inhibition of D. desulfuricans was observed to be a reversible process. © 1992 John Wiley & Sons, Inc.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260400612
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  • 9
    Electronic Resource
    Electronic Resource
    Effects of temperature and phosphorous concentration on microbial sulfate reduction by Desulfovibrio desulfuricans (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 39 (1992), S. 1031-1042 
    Details
    ISSN: 0006-3592
    Keywords: D. desulfuricans ; sulfate reduction ; phosphorous limitation ; kinetics ; stoichiometry ; temperature effect ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The effects of temperature and phosphorous concentration on the rate and the extent of microbial sulfate reduction with lactate as carbon and energy source were investigated for Desulfovibrio desulfuricans. The continuous culture experiments (chemostat) were conducted at pH 7.0 from 12 to 48°C. The maximum specific growth rate (μmax) was relatively constant in the range 25°C-43°C and dramatically decreased outside this temperature range. The half-saturation coefficient was minimum at 25°C. Cell yield was highest in the optimum temperature range (35°C-43°C) for growth. Maintenance energy requirements for D. desulfuricans were not significant. Two moles of lactate is consumed for every mole of sulfate reduced, and this stoichiometric ratio is not temperature dependent. Steady state rate and stoichiometric coefficients accurately predicted transient behavior during temperature shifts. The extent of extracellular polymeric substance (EPS) is related to the concentration of phosphorous in the medium. EPS production rate increased with decreased phosphorous loading rate. Failure to discriminate between cell and EPS formation by D. desulfuricans leads to significant overestimates of the cell yield. The limiting C:P ratio for D. desulfuricans was in the range of 400:1 to 800:1.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260391007
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  • 10
    Electronic Resource
    Electronic Resource
    Specifische Wärme des Zirkoniums, Siliciums und Bors (1873)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 169 (1873), S. 388-392 
    Details
    ISSN: 0075-4617
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.18731690307
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