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  • 1
    Electronic Resource
    Electronic Resource
    Secretory and Morphological Heterogeneity of Porcine Somatotropes during Postnatal Development (1997)
    Oxford, UK : Blackwell Science Ltd
    Journal of neuroendocrinology 9 (1997), S. 0 
    Details
    ISSN: 1365-2826
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Previous studies from our laboratory have demonstrated that porcine somatotropes can be separated into two subpopulations of low (LD) and high density (HD) by centrifugation in a Percoll gradient. The two subsets are present throughout porcine postnatal growth, although their relative proportions vary with age. In prepubertal animals, HD cells exhibit higher secretory granule content and release more GH than LD cells under basal culture conditions. In the present study, we analysed the ultrastructure of separated LD and HD cells from neonate and mature female pigs, and quantified cell size as well as the relative abundance of several subcellular organelles on immunoidentified somatotropes. Subsequently, GH release under basal conditions was assessed for cultures of unseparated cells and also for LD and HD somatotropes obtained at different stages of postnatal development. Results from the morphometric study demonstrated that LD somatotropes were significantly smaller in size, contained less secretory granules and displayed a more developed endoplasmic reticulum than their HD counterparts, regardless of the age of the pituitary donors. In terms of secretory ability, a significant age-associated decrease in GH release was observed in monolayer cultures of unseparated cells from prepubertal and mature pigs compared to neonates. A similar decline in GH-releasing ability was detected for cultures of HD cells. For LD cells, GH secretion only decreased significantly in mature animals. In spite of the divergent pattern followed by both subpopulations during growth, HD somatotropes released significantly more GH than LD somatotropes at the three ages studied. Taken together, our findings demonstrate that the population of porcine somatotropes is mainly composed of two subtypes, LD and HD, which differ in density, morphology and basal secretory activity. These differences are essentially maintained during porcine postnatal development. The progressive reduction in the secretory capacity of HD and LD somatotropes, coupled to the decrease in the relative abundance reported for the HD subpopulation, provides the cytological basis for a better understanding of the decline in GH release associated with age in pigs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2826.1997.00642.x
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  • 2
    Electronic Resource
    Electronic Resource
    Carbon and nitrogen transformation during composting of sweet sorghum bagasse (1996)
    Springer
    Biology and fertility of soils 22 (1996), S. 141-148 
    Details
    ISSN: 1432-0789
    Keywords: Composting ; Organic matter degradation ; Humification ; Nitrogen forms ; Sweet sorghum bagasse
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Two types of compost, consisting of sweet sorghum bagasse with either sewage sludge or a mixture of pig slurry and poultry manure, were studied in a pilot plant using the Rutgers system. The total degradation of the piles as determined by the weight loss of organic matter during the bio-oxidative and maturation phases accounted for 64% of the organic matter applied and followed a first-order kinetic function. Concentrations of total and organic N increased during the composting process as the degradation of organic C compounds reduced the compost weight. Losses of N through NH3 volatilization were low, particularly in the compost with sewage sludge due to pH values of 〈7.0 and the low temperatures reached in the compost during the first 2 weeks. The C:N ratio in the two composts decreased from 24.0 and 15.4 to values between 12 and 10. Increases in cation exchange capacity and in fulvic and humic acid-like C revealed that the organic matter had been humified during composting. The humification index, the C:N ratio, fulvic:humic acid-like C, and cation exchange capacity proved to be the most suitable parameters for assessing the maturity of these composts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00384446
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  • 3
    Electronic Resource
    Electronic Resource
    Carbon and nitrogen transformation during composting of sweet sorghum bagasse (1996)
    Springer
    Biology and fertility of soils 22 (1996), S. 141-148 
    Details
    ISSN: 1432-0789
    Keywords: Key words Composting ; Organic matter degradation ; Humification ; Nitrogen forms ; Sweet sorghum bagasse
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Two types of compost, consisting of sweet sorghum bagasse with either sewage sludge or a mixture of pig slurry and poultry manure, were studied in a pilot plant using the Rutgers system. The total degradation of the piles as determined by the weight loss of organic matter during the bio-oxidative and maturation phases accounted for 64% of the organic matter applied and followed a first-order kinetic function. Concentrations of total and organic N increased during the composting process as the degradation of organic C compounds reduced the compost weight. Losses of N through NH3 volatilization were low, particularly in the compost with sewage sludge due to pH values of 〈7.0 and the low temperatures reached in the compost during the first 2 weeks. The C:N ratio in the two composts decreased from 24.0 and 15.4 to values between 12 and 10. Increases in cation exchange capacity and in fulvic and humic acid-like C revealed that the organic matter had been humified during composting. The humification index, the C:N ratio, fulvic:humic acid-like C, and cation exchange capacity proved to be the most suitable parameters for assessing the maturity of these composts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00384446
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  • 4
    Electronic Resource
    Electronic Resource
    Production of ethanol by yeasts immobilized in pectin (1983)
    Springer
    Applied microbiology and biotechnology 17 (1983), S. 148-151 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Yeasts cells (Saccharomyces cerevisiae) were immobilized by occlusion in pectin gel, no significant changes in their biological activity being observed. The ethanol production rate was found to be negatively affected by the diameter of the beads when the cell concentration in them was high. The fermentative activity was only slightly modified by pectin concentration. Cells maintained their growth capacity and the beads could be reutilized several times in succesive batch fermentations. After freeze-drying and storage at room temperature the beads retained both their morphological and mechanical characteristics as well as 93% of their initial fermentative activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00505879
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  • 5
    Electronic Resource
    Electronic Resource
    Agrobacterium-mediated transformation of sweet orange and regeneration of transgenic plants (1995)
    Springer
    Plant cell reports 14 (1995), S. 616-619 
    Details
    ISSN: 1432-203X
    Keywords: Citrus sinensis L. Osbeck cv. Pineapple ; Sweet orange ; Agrobacterium tumefaciens ; Genetic transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Transgenic sweet orange (Citrus sinensis L. Osbeck) plants have been obtained by Agrobacterium tumefaciens-mediated gene transfer. An hypervirulent A. tumefaciens strain harboring a binary vector that contains the chimeric neomycin phosphotransferase II (NPT II) and ß-glucuronidase (GUS) genes was cocultivated with stem segments from in vivo grown seedlings. Shoots regenerated under kanamycin selection were harvested from the stem segments within 12 weeks. Shoot basal portions were assayed for GUS activity and the remaining portions were shoot tip grafted in vitro for production of plants. Integration of the GUS gene was confirmed by Southern analysis. This transformation procedure showed the highest transgenic plant production efficiency reported for Citrus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00232724
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  • 6
    Electronic Resource
    Electronic Resource
    Morphometric evaluation of subcellular changes induced by in vivo TRH treatment in the pituitary gland of Rana perezi: Effects on prolactin and thyrotropic cells (1989)
    Springer
    Cell & tissue research 256 (1989), S. 391-398 
    Details
    ISSN: 1432-0878
    Keywords: Pars distalis ; Prolactin/thyrotropic cells ; TRH ; Immunocytochemistry ; Morphometry ; Rana perezi (Anura)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The effects of synthetic thyrotropin-releasing hormone on pituitary prolactin and thyrotropic cells were investigated in adult male Rana perezi (formerly Rana ridibunda) frogs. Animals were given daily injections of synthetic thyrotropin-releasing hormone into the dorsal lymph sac. Prolactin and thyrotropic cells were identified by the colloidal-gold method, using anti-human prolactin and anti-human-β-thyrotropin hormone as primary antisera. The stereological parameters of the rough endoplasmic reticulum, Golgi complex, and secretory granules of prolactin and thyrotropic cells were evaluated by ultrastructural morphometry (point-counting method). Thyrotropin-releasing hormone caused cytological changes in both cell-types which were consistent with increased synthesis and release of both prolactin and thryrotropin. These changes were still significant after 48 h treatment in the case of thyrotropic cells, while in prolactin cells the thyrotropin-releasing hormone increased the number of secretory granules. After 6 days, the cells resembled essentially those used as controls. These results indicate that thyrotropin-releasing hormone stimulates the synthesis and release of prolactin and thyrotropin, and that the response of each cell type to this hypothalamic stimulus follows a different time-course.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00218897
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  • 7
    Electronic Resource
    Electronic Resource
    Genetic transformation and regeneration of mature tissues of woody fruit plants bypassing the juvenile stage (1998)
    Springer
    Transgenic research 7 (1998), S. 51-59 
    Details
    ISSN: 1573-9368
    Keywords: sweet orange ; Citrus ; woody ; transformation ; Agrobacterium ; mature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Regeneration and transformation systems from mature plant material of woody fruit species have to be achieved as a necessary requirement for the introduction of useful genes into specific cultivars and the rapid evaluation of resulting horticultural traits. We report here, for the first time, a procedure for genetic transformation and regeneration of mature tissues of woody plants that overcomes the long juvenile periods and high heterozygosity that are characteristic of most of these species. An improved regeneration frequency from mature explants was obtained by invigoration of the plant material through grafting of mature buds on juvenile seedlings. Co-cultivation of the explants in feederplates after inoculation with Agrobacterium tumefaciens resulted in enhanced transformation frequencies. Furthermore, in vitro shoot-tip grafting of the regenerated mature shoots on seedling rootstocks provided a rapid and efficient system for plant production. Citrus is the most extensivel y grown fruit crop worldwide and sweet orange (Citrus sinensis L. Osbeck) accounts for approximately 70% of the Citrus total production. Mature transgenic sweet orange plants have been obtained, which flowered and bore fruit in 14 months
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008855922283
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  • 8
    Electronic Resource
    Electronic Resource
    Production of pectinases byAspergillus sp using differently pretreated lemon peel as the carbon source (1986)
    Springer
    Biotechnology letters 8 (1986), S. 501-504 
    Details
    ISSN: 1573-6776
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Aspergillus sp strains from decaying lemons were tested for extracellular pectinase production, testing differently pretreated lemon peel as the carbon source instead of pectin. It was found that the production of extracellular polygalacturonase was about the same and that of pectinesterase substantially higher when unwashed fresh lemon peel was used instead of pectin. The culture filtrate obtained showed a clarifying capacity similar to that of a commercial pectinase preparation, but the vitamin C of the juice was less affected by the treatment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01025209
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  • 9
    Electronic Resource
    Electronic Resource
    Horizontal reactor for the continuous production of ethanol by yeasts immobilized in pectin (1984)
    Springer
    Biotechnology letters 6 (1984), S. 465-470 
    Details
    ISSN: 1573-6776
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Yeast cells (Saccharomyces cerevisiae) were immobilized in pectin gel, incubated 12 h at 30°C and then used for the continuous production of ethanol employing a wedge-shaped horizontal reactor and sugar cane molasses as the carbon source. Under steady state conditions the mean residence time was 1.6 h and the volumetric productivity 40 g EtOH/hl. The gas evolved was easily released. Successive batch incubation in a synthetic medium substantially restored the fermentative capacity of the beads already used in the continuous assay.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00129311
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  • 10
    Electronic Resource
    Electronic Resource
    Effects of furfural on ethanol fermentation bySaccharomyces cerevisiae: Mathematical models (1994)
    Springer
    Current microbiology 29 (1994), S. 87-90 
    Details
    ISSN: 1432-0991
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Different inocula with high yeast concentration were investigated as a means of overcoming the inhibitory effect of furfural in ethanol fermentation. In order to verify the toxicity of the furfural, a series of fermentation runs were made with 0.25, 5.50, and 9.00 g/L (dry weight) ofSaccharomyces cerevisiae inoculum and 1, 3, and 5 g/L of furfural. The extent of cell death occurring in the early phase of fermentation was dependent on the initial cell concentration. With high initial yeast concentration, the effect of furfural is canceled, because it is depleted at an early stage of fermentation. The ethanol weight yield averaged 0.45 on the basis of sugar consumed. The ethanol productivity and specific growth rate decreased with the increase of furfural concentration, and the inhibitory effect almost disappeared with high cell concentration (9 g/L). Mathematical models were developed that relate productivity and growth rate with furfural and cell concentration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01575753
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