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排序方式: 共有249条查询结果,搜索用时 15 毫秒
31.
Celebrants and the Celebrity: Biography as Trope 总被引:1,自引:0,他引:1
32.
A novel multi-coaxial hollow fiber bioreactor for adherent cell types. Part 1: hydrodynamic studies.
Stephen P Wolfe Edward Hsu Lola M Reid Jeffrey M Macdonald 《Biotechnology and bioengineering》2002,77(1):83-90
A novel multi-coaxial bioreactor for three-dimensional cultures of adherent cell types, such as liver, is described. It is composed of four tubes of increasing diameter placed one inside the other, creating four spatially isolated compartments. Liver acinar structure and physiological parameters are mimicked by sandwiching cells in the space between the two innermost semi-permeable tubes, or hollows fibers, and creating a radial flow of media from an outer compartment (ECC), through the cell mass compartment, and to an inner compartment (ICC). The outermost compartment is created by gas-permeable tubing, and the housing is used to oxygenate the perfusion media to periportal levels in the ECC. Experiments were performed using distilled water to correlate the radial flow rate (Q(r)) with (1) the pressure drop (DeltaP) between the media compartments that sandwich the cell compartment and (2) the pressure in the cell compartment (P(c)). These results were compared with the theoretical profile calculated based on the hydraulic permeability of the two innermost fibers. Phase-contrast velocity-encoded magnetic resonance imaging was used to visualize directly the axial velocities inside the bioreactor and confirm the assumptions of laminar flow and zero axial velocity at the boundaries of each compartment in the bioreactor. Axial flow rates were calculated from the magnetic resonance imaging results and were similar to the measured axial flow rates for the previously described experiments. 相似文献
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Biologia Plantarum - According to plant age at induction and rate of initial growth ABA leads either to stimulation or inhibition of growth and flowering in youngChenopodium rubrum plants. This... 相似文献
35.
Abstract An Escherichia coli clone containing recombinant plasmid C19 was identified from a Treponema pallidum genomic DNA library by in situ immunoassay. E. coli maxicells containing pC19 synthesized a treponemal protein doublet of 39.2 and 38.2 kDa, designated TpN38(b). Pulse-chase and protein processing studies showed that TpN38(b) is synthesized with a cleavable amino-terminal signal peptide. A 2.0-kb fragment of pC19 containing the tpn38(b) gene was subcloned and sequenced. The tpn38(b) gene is 1029 nucleotides long and encodes a protein of 343 amino acids with a calculated molecular mass of 37.9 kDa. The deduced amino acid sequence of TpN38(b) has homology with the T. pallidum TpN35 lipoprotein and the Borrelia burgdorferi BmpA, BmpB, BmpC, and BmpD proteins. 相似文献
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Maria Agelli Elaine D. Halay Lola M. Reid Persio Dello Sbarba Ronald A. Faris Douglas E. Hixson 《Journal of molecular histology》1997,29(3):205-217
Oval cells proliferate extensively in the livers of animals exposed to oncogenic insults, are bipotent and are believed to
be related to the so far unidentified liver stem cell. In normal liver, cells antigenica lly related to oval cells and expressing
liver and epithelial markers are considered to be liver progenitor cells. We isolated, by fluorescence-activated cell sorting
or magnetic bead sorting, cells expressing the oval cell antigens OC.2 or OC.3 from the liver of normal newborn or day 12
embryonal age rats. Magnetic bead sorting of positive cells was as efficient as fluorescence-activated cell sorting. A two-chamber
culture system was devised in which cells were plated onto transwell filters coated with type IV collagen and cultured in
a serum-free Ham's F12 medium supplemented with free fatty acids and bovine serum albumin. Under these conditions, cells remained
viable for up to 6 weeks and their antigenic phenotype was unchanged throughout. Approximately 30% of sorted cells expressed
epithelial and/or liver-specific markers. Growth factors mitogenic for epithelial cells and hepatocytes did not elicit cell
proliferation. These results provide an important background for further studies designed to determine the biological significance
of OC.2+ and OC.3+ cells in normal liver, to test the liver stem cell hypothesis and to develop protocols for the expansion in vitro of normal
liver progenitors.
This revised version was published online in November 2006 with corrections to the Cover Date. 相似文献
38.
Lola Teltscherová 《Biologia Plantarum》1970,12(2):134-138
CCC (2-chloroethyl)trimethylammonium chloride applied to plants ofChenopodium rubrum during floral induction led to an increase in the level of endogenous cytokinins in the apical buds. Application of gibberellic acid or indole-3-acetic acid at concentrations reversing the effect of CCC reduced the level of cytokinins. After simultaneous treatment with both CCC and one of the growth substances this reduction was less pronounced. From the comparison bf the present results, as well as of those published in previous papers it follows that in apical buds ofChenopodium rubrum there exists a mutual interaction between gibberellins and cytokinins. Under certain conditions both these groups of hormones may substitute for each other in flowering. IAA seems to affect flowering by regulating the level of both gibberellins and cytokinins. 相似文献
39.
Puig S Mira H Dorcey E Sancenón V Andrés-Colás N Garcia-Molina A Burkhead JL Gogolin KA Abdel-Ghany SE Thiele DJ Ecker JR Pilon M Peñarrubia L 《Biochemical and biophysical research communications》2007,354(2):385-390
Copper (Cu) chaperones constitute a family of small Cu+-binding proteins required for Cu homeostasis in eukaryotes. The ATX1 family of Cu chaperones specifically delivers Cu to heavy metal P-type ATPases. The plant Arabidopsis thaliana expresses the ATX1-like Cu chaperone CCH, which exhibits a plant-specific carboxy-terminal domain (CTD) with unique structural properties. We show that CCH homologues from other higher plants contain CTDs with structural properties similar to Arabidopsis CCH. Furthermore, we identify a new ATX1-like Cu chaperone in Arabidopsis, AtATX1, which functionally complements yeast atx1Delta and sod1Delta associated phenotypes, and localizes to the cytosol of Arabidopsis cells. Interestingly, AtATX1, but not full-length CCH, interacts in vivo with the Arabidopsis RAN1 Cu-transporting P-type ATPase by yeast two-hybrid. We propose that higher plants express two types of ATX1-like Cu chaperones: the ATX1-type with a predominant function in Cu delivery to P-type ATPases, and the CCH-type with additional CTD-mediated plant-specific functions. 相似文献
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