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11.
Panose, a major component of isomalto-oligosaccharides, was selectively produced from maltose using transglucosylation reaction catalyzed by intact cells of Aureobasidium pullulans. When 50 %(w/v) maltose was used as a substrate, the maximum concentration of panose accumulated in the final reaction mixture was about 50 %(w/w) after 120 hr reaction at 55 °C. 相似文献
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Hyun Koo Kim Moon Sun Ham Jong Soo Hong Jin Ha Lee Kyung Yu Park Hyeon Yong Lee 《Biotechnology and Bioprocess Engineering》1996,1(1):32-35
A moving aeration-membrane (MAM) bioreactor was employed for the production of 2 μg/mL of tissue type Plasminogen Activator (tPA) in serum free medium from normal human fibroblast cells. This system could maintain high cell density for long periods of steady state conditions in perfusion cultivation. Under normal operating conditions, shear stress was as low as 0.65 dynes/cm2 at the agitation speed of 80 rpm. Even though cell density gradually decreased with increasing agitation speed, tPA production increased linearly with increasing shear stress within a moderate range. This culture system allowed production of 2 μg tPA/mL while maintaining a high cell density of 1.0×107 viable cells/mL. 相似文献
15.
A highly conserved nuclear gene for low-level phylogenetics: elongation factor-1 alpha recovers morphology-based tree for heliothine moths 总被引:8,自引:2,他引:6
Cho S; Mitchell A; Regier JC; Mitter C; Poole RW; Friedlander TP; Zhao S 《Molecular biology and evolution》1995,12(4):650-656
Molecular systematists need increased access to nuclear genes. Highly
conserved, low copy number protein-encoding nuclear genes have attractive
features for phylogenetic inference but have heretofore been applied mostly
to very ancient divergences. By virtue of their synonymous substitutions,
such genes should contain a wealth of information about lower-level
taxonomic relationships as well, with the advantage that amino acid
conservatism makes both alignment and primer definition straightforward. We
tested this postulate for the elongation factor-1 alpha (EF-1 alpha) gene
in the noctuid moth subfamily Heliothinae, which has probably diversified
since the middle Tertiary. We sequenced 1,240 bp in 18 taxa representing
heliothine groupings strongly supported by previous morphological and
allozyme studies. The single most parsimonious gene tree and the
neighbor-joining tree for all nucleotides show almost complete concordance
with the morphological tree. Homoplasy and pairwise divergence levels are
low, transition/transversion ratios are high, and phylogenetic information
is spread evenly across gene regions. The EF-1 alpha gene and presumably
other highly conserved genes hold much promise for phylogenetics of
Tertiary age eukaryote groups.
相似文献
16.
Identification of the signalling molecules involved in mesoderm formation in amphibian embryos still presents problems. None of the original candidates, such as activin, have been definitively ruled out, and the new factors, such as the nodal-related genes, have come on to the scene. Of the original candidates, activin has been definitively shown to act as a morphogen, whereas bone morphogenetic protein (BMP)-4 has emerged as a ventral inducer and an inhibitor of neural differentiation. The effects of BMP-4 are antagonized by chordin, a molecule related to the product of the Drosophila gene short gastrulation. 相似文献
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Sexual and somatic determinants of the human Y chromosome: studies in a 46,XYp- phenotypic female. 总被引:5,自引:0,他引:5
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R G Rosenfeld L Luzzatti R L Hintz O J Miller G C Koo S S Wachtel 《American journal of human genetics》1979,31(4):458-468
A case of a 46,XYp- phenotypic female provided an opportunity to evaluate both sexual and somatic determinants for the Y chromosome. The patient had multiple stigmata of Turner syndrome, but normal stature. Laparotomy revealed a normal uterus and tubes, with 1.5 cm undifferentiated gonads. Serological tests for H-Y antigen (ostensibly the product of Y-chromosomal testis-determining genes) indicated absence of the H-Y+ phenotype normally associated with the intact Y chromosome. We conclude that genes exist on the short arm of the human Y chromosome which both suppress some of the somatic stigmata of Turner syndrome and determine normal expression of H-Y antigen and testicular differentiation of the primitive gonad. Our data are consistent with the view that H-Y genes comprise a family of testis-determinants, and that loss of a critical moiety is inconsistent with normal development of the male gonad. 相似文献
20.
Subunit and primary structure of a mouse alpha-macroglobulin, a human alpha 2-macroglobulin homologue 总被引:4,自引:0,他引:4
A mouse alpha-macroglobulin (AMG), a homologue of human alpha 2-macroglobulin (alpha 2 M), has been purified to homogeneity. In contrast to human and acute-phase rat alpha 2 M which contains subunits of about Mr 190 000, the mouse protein contains two major (Mr 163000 and 35000) and one minor (Mr 185000) subunits. Also unlike human alpha 2 M, which can be broken down into about 85000-dalton subunits when reacted with an endopeptidase, the native AMG is cleaved by trypsin into multiple components (Mr 86000, 63000, 61000 and 33000). Two-dimensional peptide map analysis of these various 125I-labeled subunit components reveals that the 185000- and 163000-dalton components are homologous proteins but only the 185000-dalton protein contains the 35000-dalton component. The 163000-dalton protein is cleaved by trypsin into 86000- and 63000-dalton components, and the 86-kDa component in turn can be broken down into 61000- and 33000-dalton fragments. Since the 35000-dalton component is serologically related to AMG but does not share any tryptic peptides with both the 163000- and 33000-dalton components, it is neither a copurified impurity nor a cleavage product of the major (163000-dalton) subunit. AMG, therefore, is composed of covalently linked subunits of Mr 163000 and 35000, and the 185000-dalton protein may be a variant subunit of AMG. Trypsin treatment of the [14C]methylamine-labeled AMG and alpha 2 M also sequentially generate subunit patterns indistinguishable from those of the unlabeled macroglobulins. The methylamine-sensitive site(s) of AMG is localized in the 63000-dalton peptide, which is rather resistant to trypsin digestion and to staining by Coomassie brillant blue. We conclude from this study that the mouse homologue has a subunit composition and primary structure distinctly different from those of human and rat alpha 2 M. 相似文献