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81.
During the development of the proventriculus (glandular stomach) of the chicken embryo, the endodermal epithelium invades into the surrounding mesenchyme and forms glands. The glandular epithelial cells produce pepsinogen, while the non-glandular (luminal) epithelial cells secrete mucus. Sonic hedgehog is expressed uniformly in the proventricular epithelium before gland formation, but its expression ceases in gland cells. Here we present evidence that down-regulation of Sonic hedgehog is necessary for gland formation in the epithelium using a specific inhibitor of Sonic hedgehog signaling and virus mediated overexpression of Sonic hedgehog. We also show that gland formation is not induced by down-regulation of Sonic hedgehog alone; a mesenchymal influence is also required. 相似文献
82.
83.
Molecular and Cellular Biochemistry - 2,3-Bisphosphoglycerate accumulates in mammalian erythrocytes, where it facilitates the supply of oxygen to the tissues by binding to hemoglobin. Regulatory... 相似文献
84.
Quantification of self-renewal capacity in single hematopoietic stem cells from normal and Lnk-deficient mice 总被引:8,自引:0,他引:8
Ema H Sudo K Seita J Matsubara A Morita Y Osawa M Takatsu K Takaki S Nakauchi H 《Developmental cell》2005,8(6):907-914
Despite being a hallmark of hematopoietic stem cells (HSCs), HSC self-renewal has never been quantitatively assessed. Establishment of a clonal and quantitative assay for HSC function permitted demonstration that adult mouse HSCs are significantly heterogeneous in degree of multilineage repopulation and that higher repopulating potential reflects higher self-renewal activity. An HSC with high repopulating potential could regenerate approximately 1000 HSCs, whereas the repopulating activity of regenerated HSCs on average was significantly reduced, indicating extensive but limited self-renewal capacity in HSCs. Comparisons of wild-type mice with mutant mice deficient in the signal adaptor molecule Lnk showed that not only HSC numbers but also the self-renewal capacity of some HSCs are markedly increased when Lnk function is lost. Lnk appears to control HSC numbers by negatively regulating HSC self-renewal signaling. 相似文献
85.
86.
Akira Matsumoto Hideo Yoshima Sakan Maeda Nobuyuki Shiraishi Akira Kobata 《Archives of biochemistry and biophysics》1982,217(2):682-695
The asparagine-linked sugar chains of the plasma membrane glycoproteins of rat erythrocytes were released as oligosaccharides by hydrazinolysis and labeled by NaB3H4 reduction. The radioactive oligosaccharides were separated into a neutral and at least four acidic fractions by paper electrophoresis. The neutral oligosaccharide fraction was separated into at least 11 peaks upon Bio-Gel P-4 column chromatography. Structural studies of them by sequential exoglycosidase digestion in combination with methylation analysis revealed that they were a mixture of three high mannose-type oligosaccharides and at least 11 complex type oligosaccharides with Manα1 → 6(Manα1 → 3)Manβ1 → 4GlcNAcβ1 → 4(±Fucα1 → 6)GlcNAc as their cores and Galβ1 → 4GlcNAc, Galβ1 → 3Galβ1 → 4GlcNAc, and various lengths of Galβ1 → 4GlcNAc repeating chains in their outer chain moieties. Most of the complex-type Oligosaccharides were biantennary, and the tri- and tetraantennary Oligosaccharides contain only the Galβ1 → 3Galβ1 → 4GlcNAc group in their outer chain moieties. 相似文献
87.
88.
Bo Zhu Rui Gan Maria D. Cabezas Takaaki Kojima Robert Nicol Michael C. Jewett Hideo Nakano 《Biotechnology and bioengineering》2020,117(12):3849-3857
In crude extract-based cell-free protein synthesis (CFPS), DNA templates are transcribed and translated into functional proteins. Although linear expression templates (LETs) are less laborious and expensive to generate, plasmid templates are often desired over polymerase chain reaction-generated LETs due to increased stability and protection against exonucleases present in the extract of the reaction. Here we demonstrate that addition of a double stranded DNA-binding protein to the CFPS reaction, termed single-chain Cro protein (scCro), achieves terminal protection of LETs. This CroP-LET (scCro-based protection of LET) method effectively increases superfolder green fluorescent protein (sfGFP) expression levels from LETs in Escherichia coli CFPS reactions by sixfold. Our yields are comparable to other strategies that provide chemical and enzymatic DNA stabilization in E. coli CFPS. Notably, we also report that the CroP-LET method successfully enhanced yields in CFPS platforms derived from nonmodel organisms. Our results show that CroP-LET increased sfGFP yields by 18-fold in the Vibrio natriegens CFPS platform. With the fast-expanding applications of CFPS platforms, this method provides a practical and generalizable solution to protect linear expression DNA templates. 相似文献
89.
Hideo Kimura Samuel A. Burstein David Thorning Jerry S. Powell Laurence A. Harker Philip J. Fialkow John W. Adamson 《Journal of cellular physiology》1984,118(1):87-96
The basic culture requirements and several physical characteristics were defined for megakaryocytic colony-forming cells (CFU-M) from normal human marrow growing in methylcellulose. Ficoll-hypaque separated mononuclear cells from human, marrow gave rise to megakaryocytic colonies in the presence of normal human plasma and phytohemagglutinin-stimulated leukocyte-conditioned medium (PHA-LCM). Their identity as megakaryocytic colonies was confirmed by immunofluorescence staining with a monoclonal antibody to human factor VIII antigen and by electron microscopy of individually harvested colonies. Demonstration of the single-cell origin of the colonies was provided by analysis of the glucose-6-phosphate dehydrogenase (G-6-PD) enzyme type of individually harvested colonies grown from a G-6-PD heterozygote. The colonies grew best in heparinized or citrated plasma as opposed to serum. Detailed studies suggested that platelet-release products were responsible for this difference. Tritiated thymidine suicide studies showed that the percentage of CFU-M in DNA synthesis was 23 ± 8% (n = 10). The modal velocity sedimentation rate of CFU-M was 4.9 ± 0.6 mm/hr (n = 4) while that of concurrently studied granulocyte/macrophage colony-forming cells (CFU-GM) was 5.7 ± 0.5 mm/hr. Examination of the PHA-LCM dose-response characteristics suggested the presence in the conditioned medium of an inhibitor to megakaryocyte colony growth which was partially removed by chromatography of the medium on Sephadex G-100. The resulting conditioned medium increased the cloning efficiency for CFU-M compared with that with crude PHA-LCM (15.3 ± 7.0 and 8.2 ± 5.3/105 marrow cells, respectively). 相似文献
90.
Fukushima A Yamaguchi T Ishida W Fukata K Mittler RS Yagita H Ueno H 《Journal of immunology (Baltimore, Md. : 1950)》2005,175(8):4897-4903
The 4-1BB receptor acts as a costimulator in CD8(+) T cell activation. Agonistic stimulation through this molecule by treatment with anti-4-1BB Abs has been demonstrated to inhibit various experimentally induced diseases in animals. However, the effect of anti-4-1BB Abs on experimental allergic diseases has not been reported. We investigated the effect of anti-4-1BB Abs on the development and progression of experimental allergic conjunctivitis in mice. To examine the effects of Abs during the induction or effector phase, actively immunized mice or passively immunized mice by splenocyte transfer were treated with agonistic anti-4-1BB Abs, blocking anti-4-1BB ligand Abs, or normal rat IgG. Eosinophil infiltration into the conjunctiva was significantly reduced in wild-type mice by the anti-4-1BB Ab treatment during either induction or effector phase. Th2 cytokine production by splenocytes and total serum IgE were significantly reduced by the anti-4-1BB Ab treatment, while IFN-gamma production was increased. The anti-4-1BB Ab treatment induced a relative increase of CD8-positive cell numbers in the spleens. Moreover, inhibition of eosinophil infiltration by the treatment with anti-4-1BB Abs was also noted in actively immunized IFN-gamma knockout mice. Taken altogether, in vivo treatment with agonistic anti-4-1BB Abs in either induction or effector phase inhibits the development of experimental allergic conjunctivitis, and this inhibition is likely to be mediated by suppression of Th2 immune responses rather than up-regulation of IFN-gamma. 相似文献