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11.
Catherine Manin Jean Noël Barbotin Daniel Thomas Jean Claude Lazzaroni 《Applied microbiology and biotechnology》1989,32(2):143-147
Summary In continuous cultures, alkaline phosphatase was synthesised and excreted for more than 250 h by immobilized growing cells in contrast to free cells for which the excretion decreased after 150 h of culture. This observed increase in alkaline phosphatase synthesis and excretion by immobilized cells may have resulted from growing conditions within the gel beads.Offprint requests to: C. Manin 相似文献
12.
José Edmundo Nava Saucedo Jean-Noël Barbotin Daniel Thomas 《Applied microbiology and biotechnology》1989,30(3):226-233
Summary The continuous production of gibberellic acid with immobilized mycelia of Gibberella fujikuroi was maintained over a hundred days in a tubular fixed-bed reactor. Free mycelium at the beginning of the storage phase was harvested from G. fujikuroi shake-flask culture and was immobilized by ionotropic gelation in calcium alginate beads.The continuous recycle production system consisted of a fixed-bed reactor, a container in which the culture medium was heated, stirred and aerated, and valves for sample withdrawal or reactant addition during the first 1320 h (55 days). A two-phase continuous extractor was then added for the last 960 hours (40 days). Free and immobilized mycelium shake-flask cultures with the same strain used in the continuous culture system were also realized to compare growth, maintenance and production parameters. The results show about the same gibberellic acid productivity in both free and immobilized mycelium shakeflask cultures: 0.384 and 0.408 mgGA3·gBiomass-1 ·day-1, respectively, whereas in the continuous system the gibberellic acid production is about twice as large for a similar biomass: 0.768 mgGA3·gBiomass-1·day-1. Several factors affecting the overall productivity of the immobilized systems were found to be: the quality and the quantity of mycelia in the biocatalyst beads and the immobilization conditions. 相似文献
13.
A minority of 46,XX true hermaphrodites are positive for the Y-DNA sequence including SRY 总被引:4,自引:0,他引:4
Ken McElreavey Raphaël Rappaport Eric Vilain Nacer Abbas François Richaud Stéphen Lortat-Jacob Roland Berger Maryvonne LeConiat Chafika Boucekkine Kiran Kucheria Samia Temtamy Claire Nihoul-Fekete Raja Brauner Marc Fellous 《Human genetics》1992,90(1-2):121-125
Summary A total of 30 cases of 46,XX true hermaphroditism was analysed for Y-DNA sequences including the recently cloned gene for male testis-determination SRY. In 3 cases, a portion of the Y chromosome including SRY was present and, in 2 cases, was localised, to Xp22 by in situ hybridisation. Since previous studies have shown that the majority of XX males are generated by an X-Y chromosomal interchange, the Xp22 position of the Yp material suggests that certain cases of hermaphroditism can arise by the same meiotic event. The phenotype in the 3 SRY-positive cases may be caused by X-inactivation resulting in somatic mosaicism of testis-determining factor expression giving rise to both testicular and ovarian tissues. Autosomal or X-linked mutation(s) elsewhere in the sex-determining pathway may explain the phenotype observed in the remaining 27 SRY-negative cases. 相似文献
14.
15.
By using simultaneously the AgNOR silver staining method, back-scattered electron imaging mode and stereo-tilt in scanning electron microscopy (SEM), it is possible to observe the nucleus through the cell surface, the nucleolus, and the tri-dimensional distribution of the AgNOR-associated acidic proteins. In C3H10T1:2 cells and their 7-12-dimethylbenz--anthracene-treated transformants, the staining demonstrates several intranucleolar silver-staining granules (SSG), surrounded by a weakly staining region. The SSG may represent the fibrillar center (FC) and the weakly staining region, the fibrillar dense component (FD). This component can link several SSG together to form a rope-like structure. In cells with no visible nucleolus and inactive nucleolar organizer regions (NORs) the silver-staining granules are less numerous, close together and the presumed fibrillar dense components are not visible. The SSG are located more peripheraly, and the weakly staining region and the rope-like structure are less prominent in control cell nucleoli than in transformed cells with a comparatively high rate of RNA synthesis. 相似文献
16.
The protein synthesis activity of heart, skeletal muscle and liver polysomes from isoprotenerol-treated and control hamsters has been compared in an in vitro non-inititating translation system. Heart and skeletal muscle polysomes from treated hamsters were less active than controls and required a higher magnesium concentration for optimal protein synthesis. These results suggest that there is a conformational modification in heart and skeletal muscle ribosomes from isoprotenerol-treated hamsters. No such change was observed with ribosomes from the liver of isoproterenol-treated hamsters. 相似文献
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18.
Summary Expression of the anchorage-independent transformed phenotype in BHK 21/13 cells generally behaves as a recessive trait. When
chemically induced and spontaneously arising transformants are fused to the nontransformed parent line, transformation is
initially suppressed, reappearing after extended growth of the hybrids. In this paper, complementation for the expression
of anchorage independence was sought among a large group of such transformants, all independently derived from BHK 21/13 cells.
Tumorigenicity studies on selected hybrids and parental lines indicated that the in vitro trait of anchorage independence
is an accurate indicator of in vivo neoplasia for these cells. Seventeen of the 18 clones tested did not complement one or
more of three tester strains. This result indicates that anchorage independence arose in these clones as a result of lesions
in the same genetic function and suggests that the final step in the progressive changes of carcinogenesis may frequently
be restricted to lesions at a single locus.
This investigation was supported by National Institutes of Health grant CA27306. 相似文献
19.
20.
Clastogen-induced chromosomal breakage as a marker for first trimester prenatal diagnosis of Fanconi anemia 总被引:5,自引:0,他引:5
Arleen D. Auerbach Zhang Min Rita Ghosh Eugene Pergament Yuri Verlinsky Henriette Nicolas Joëlle Boué 《Human genetics》1986,73(1):86-88
Summary Using cultured trophoblast cells obtained by chorionic villus biopsy, we diagnosed Fanconi anemia (FA) in two pregnancies and excluded it in eight pregnancies at risk for the syndrome. Baseline chromosomal breakage and breakage induced by diepoxybutane (DEB) were analyzed. Increased breakage was used as a marker for the syndrome. Our results were unambiguous and provide a reliable method for prenatal detection of FA in the first trimester of pregnancy. 相似文献