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排序方式: 共有272条查询结果,搜索用时 15 毫秒
111.
112.
Romero X Zapater N Calvo M Kalko SG de la Fuente MA Tovar V Ockeloen C Pizcueta P Engel P 《Journal of immunology (Baltimore, Md. : 1950)》2005,174(11):7033-7042
CD229 is a member of the CD150 family of the Ig superfamily expressed on T and B cells. Receptors of this family regulate cytokine production and cytotoxicity of lymphocytes and NK cells. The cytoplasmic tail of CD229 binds to SAP, a protein that is defective in X-linked lymphoproliferative syndrome. To identify the CD229 ligand, we generated a soluble Ig fusion protein containing the two N-terminal extracellular domains of human CD229 (CD229-Ig). CD229-Ig bound to CD229-transfected cells, whereas no binding was detected on cells expressing other CD150 family receptors, showing that CD229 binds homophilically. Both human and mouse CD229 interacted with itself. Domain deletion mutants showed that the N-terminal Ig-domain mediates homophilic adhesion. CD229-CD229 binding was severely compromised when the charged amino acids E27 and E29 on the predicted B-C loop and R89 on the F-G loop of the N-terminal domain were mutated to alanine. In contrast, one mutation, R44A, enhanced the homophilic interaction. Confocal microscopy image analysis revealed relocalization of CD229 to the contact area of T and B cells during Ag-dependent immune synapse formation. Thus, CD229 is its own ligand and participates in the immunological synapse. 相似文献
113.
S Jahan S Singh A Srivastava V Kumar D Kumar A Pandey CS Rajpurohit AR Purohit VK Khanna AB Pant 《Molecular neurobiology》2018,55(4):2828-2839
114.
Somatic and Meiotic Chromosomal Recombination between Inverted Duplications in Transgenic Tobacco Plants 总被引:11,自引:2,他引:9 下载免费PDF全文
Homologous recombination has been extensively studied in bacteria, yeast, and more recently in animal cells, but little is known about this process in plants. We present here an analysis of meiotic and somatic chromosomal recombination between closely linked inverted duplications located on a single chromosomal region in tobacco. Transgenic tobacco lines were constructed by Agrobacterium transformation with plasmid vectors containing a functional hygromycin phosphotransferase (hyg) selectable marker flanked by a pair of defective neomycin phosphotransferase (neo) genes positioned as inverted repeats. As each neo gene is mutated in a different site, recombination between the two defective genes can be detected following selection for kanamycin-resistant plant cells. The recombination substrates were designed to allow investigation into the nature of molecular events underlying homologous recombination by restriction endonuclease analysis. Chromosomal recombination was studied in mitotically dividing cells (cultured leaf mesophyll cells) and after meiosis (germinated seedlings). Spontaneous somatic recombinants were recovered at frequencies between ~3 x 10-5 to 10-6 events per cell. Low dose [gamma] irradiation of somatic cells resulted in a threefold maximum increase in the recovery of recombinants. Recombinants were also detected at low frequency when transgenic T3 seeds were germinated under kanamycin selection. DNA gel blot analyses demonstrated that homologous recombination occurred mainly as gene conversion unassociated with reciprocal exchange, although a variety of other events including gene coconversion were also observed. 相似文献
115.
Goldstein DB; Zhivotovsky LA; Nayar K; Linares AR; Cavalli-Sforza LL; Feldman MW 《Molecular biology and evolution》1996,13(9):1213-1218
It has recently been suggested that observed levels of variation at
microsatellite loci can be used to infer patterns of selection in genomes
and to assess demographic history. In order to evaluate the feasibility of
these suggestions it is necessary to know something about how levels of
variation at microsatellite loci are expected to fluctuate due simply to
stochasticity in the processes of mutation and inheritance (genetic
sampling). Here we use recently derived properties of the stepwise mutation
model to place confidence intervals around the variance in repeat score
that is expected at mutation-drift equilibrium and outline a statistical
test for whether an observed value differs significantly from expectation.
We also develop confidence intervals for the time course of the buildup of
variation following a complete elimination of variation, such as might be
caused by a selective sweep or an extreme population bottleneck. We apply
these methods to the variation observed at human Y-specific
microsatellites. Although a number of authors have suggested the
possibility of a very recent sweep, our analyses suggest that a sweep or
extreme bottleneck is unlikely to have occurred anytime during the last
approximately 74,000 years. To generate this result we use a recently
estimated mutation rate for microsatellite loci of 5.6 x 10(-4) along with
the variation observed at autosomal microsatellite loci to estimate the
human effective population size. This estimate is 18,000, implying an
effective number of 4,500 Y chromosomes. One important general conclusion
to emerge from this study is that in order to reject mutation-drift
equilibrium at a set of linked microsatellite loci it is necessary to have
an unreasonably large number of loci unless the observed variance is far
below that expected at mutation-drift equilibrium.
相似文献
116.
Taku Murakami Melanie Oakes Mieko Ogura Vivian Tovar Cindy Yamamoto Masato Mitsuhashi 《PloS one》2014,9(10)
Urinary exosomes and microvesicles (EMV) are promising biomarkers for renal diseases. Although the density of EMV is very low in urine, large quantity of urine can be easily obtained. In order to analyze urinary EMV mRNA, a unique filter device to adsorb urinary EMV from 10 mL urine was developed, which is far more convenient than the standard ultracentrifugation protocol. The filter part of the device is detachable and aligned to a 96-well microplate format, therefore multiple samples can be processed simultaneously in a high throughput manner following the isolation step. For EMV mRNA quantification, the EMV on the filter is lysed directly by adding lysis buffer and transferred to an oligo(dT)-immobilized microplate for mRNA isolation followed by cDNA synthesis and real-time PCR. Under the optimized assay condition, our method provided comparable or even superior results to the standard ultracentrifugation method in terms of mRNA assay sensitivity, linearity, intra-assay reproducibility, and ease of use. The assay system was applied to quantification of kidney-specific mRNAs such as NPHN and PDCN (glomerular filtration), SLC12A1 (tubular absorption), UMOD and ALB (tubular secretion), and AQP2 (collecting duct water absorption). 12-hour urine samples were collected from four healthy subjects for two weeks, and day-to-day and individual-to-individual variations were investigated. Kidney-specific genes as well as control genes (GAPDH, ACTB, etc.) were successfully detected and confirmed their stable expressions through the two-week study period. In conclusion, this method is readily available to clinical studies of kidney diseases. 相似文献
117.
This paper presents the microstructured deposition of nanoparticles, which are chemically modified to be conjugated to biomolecules or dyes. In our approach, we separated the technical steps “surface chemistry” and “microstructuring” into two fully independent processes. This was realized by firstly synthesizing specific nanoparticles with tailor‐made surfaces. Thus, the surface chemistry was customized to the demands of most different kinds of specific proteins. Then, microstructured monolayer arrays of these nanoparticles were generated by photolithography, microcontact printing or spotting with a microarrayer. The overall system resulted in a nanoparticle‐based microarray for the selective binding of protein ligands providing both wide flexibility and high specificity. 相似文献
118.
M D Rubio F Castejón P Tovar J Ibá?ez R Santisteban 《Revista Espanola de Fisiología》1989,45(2):145-150
The effect of physical maturation on the ventricular activation and recuperation mean vectors has been analyzed in pigs during a period of time between 1 day and 6 months of age. The results showed that whilst the vectorial magnitude of AQRS on the horizontal plane was not affected by physical maturation, that of the spatial vector (SAQRS) underwent an increase during the period of study. Likewise, it was determined that the ventricular activation front showed an inclination to change its orientation from caudal, sinistral or dextral, to dextrocranial, maintaining the dorsal orientation in all individuals. For the ventricular recuperation mean vector the results showed that its vectorial magnitudes both on the horizontal plane and in space underwent an increase during the 6 months analyzed. As regards the direction of the recuperation front, it was established that, at any age, the preferential orientation is caudal, with a deviation to the left in a high percentage of the 20 day to 3 month old pigs, and ventral in all individuals. 相似文献
119.
M Kiray AR Sisman UM Camsari M Evren A Dayi B Baykara 《Biotechnic & histochemistry》2014,89(5):371-383
The developing brain is vulnerable to environmental factors. We investigated the effects of air that contained 0.05, 0.1 and 0.3% CO2 on the hippocampus, prefrontal cortex (PFC) and amygdala. We focused on the circuitry involved in the neurobiology of anxiety, spatial learning, memory, and on insulin-like growth factor-1 (IGF-1), which is known to play a role in early brain development in rats. Spatial learning and memory were impaired by exposure to 0.3% CO2 air, while exposure to 0.1 and 0.3% CO2 air elevated blood corticosterone levels, intensified anxiety behavior, increased superoxide dismutase (SOD) enzyme activity and MDA levels in hippocampus and PFC; glutathione peroxidase (GPx) enzyme activity decreased in the PFC with no associated change in the hippocampus. IGF-1 levels were decreased in the blood, PFC and hippocampus by exposure to both 0.1 and 0.3% CO2. In addition, apoptosis was increased, while cell numbers were decreased in the CA1 regions of hippocampus and PFC after 0.3% CO2 air exposure in adolescent rats. A positive correlation was found between the blood IGF-1 level and apoptosis in the PFC. We found that chronic exposure to 0.3% CO2 air decreased IGF-1 levels in the serum, hippocampus and PFC, and increased oxidative stress. These findings were associated with increased anxiety behavior, and impaired memory and learning. 相似文献
120.
Berenice Palacios-González Angel Zarain-Herzberg Isabel Flores-Galicia Lilia G. Noriega Gabriela Alemán-Escondrillas Teresa Zariñan Alfredo Ulloa-Aguirre Nimbe Torres Armando R. Tovar 《Biochimica et Biophysica Acta (BBA)/Molecular and Cell Biology of Lipids》2014,1841(1):132-140
Obesity is a public health problem that contributes to the development of insulin resistance, which is associated with an excessive accumulation of lipids in skeletal muscle tissue. There is evidence that soy protein can decrease the ectopic accumulation of lipids and improves insulin sensitivity; however, it is unknown whether soy isoflavones, particularly genistein, can stimulate fatty acid oxidation in the skeletal muscle. Thus, we studied the mechanism by which genistein stimulates fatty acid oxidation in the skeletal muscle. We showed that genistein induced the expression of genes of fatty acid oxidation in the skeletal muscle of Zucker fa/fa rats and in leptin receptor (ObR)-silenced C2C12 myotubes through AMPK phosphorylation. Furthermore, the genistein-mediated AMPK phosphorylation occurred via JAK2, which was possibly activated through a mechanism that involved cAMP. Additionally, the genistein-mediated induction of fatty acid oxidation genes involved PGC1α and PPARδ. As a result, we observed that genistein increased fatty acid oxidation in both the control and silenced C2C12 myotubes, as well as a decrease in the RER in mice, suggesting that genistein can be used in strategies to decrease lipid accumulation in the skeletal muscle. 相似文献