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991.
Targeted recruitment of a histone H4-specific methyltransferase by the transcription factor YY1 总被引:3,自引:0,他引:3
Rezai-Zadeh N Zhang X Namour F Fejer G Wen YD Yao YL Gyory I Wright K Seto E 《Genes & development》2003,17(8):1019-1029
992.
Different applications of polymerases with and without proofreading activity in single-nucleotide polymorphism analysis 总被引:2,自引:0,他引:2
Zhang J Li K Liao D Pardinas JR Chen L Zhang X 《Laboratory investigation; a journal of technical methods and pathology》2003,83(8):1147-1154
With the completion of the human genome project, single-nucleotide polymorphisms (SNPs) have become the focus of intense study in biomedical research. Polymerase-mediated primer extension has been employed in a variety of SNP assays. However, these SNP assays using polymerase without proofreading function are compromised by their low reliability. Using a newly developed short amplicon harboring restriction enzyme site, EcoR-I, we were able to compare the single-base discrimination abilities of polymerases with and without proofreading function in primer extension in a broad range of annealing temperatures. Thermodynamic analysis demonstrated a striking single-nucleotide discrimination ability of polymerases with proofreading function. Using unmodified 3'-end allele-specific primers, only template-dependent products were generated by polymerase with proofreading activity. This powerful single-base discrimination ability of exo(+) polymerases was further evaluated in primer extension using three types of 3' terminally modified allele-specific primers. As compared with the poor fidelity in primer extension of polymerases lacking 3' exonuclease activity, this study provides convincing evidence that the use of proofreading polymerases in combination with 3'-end modified allele-specific primers can be a powerful new strategy for the development of SNP assays. 相似文献
993.
It has been proposed that the structure of the exons that encode the triple helical domain of the fibrillar collagen genes arose by repeated tandem duplication of an ancestral unit exon. Because these exons encode a repeat motif [(Gly-X-Y)n], sequence homology between exons may have driven the recombinational process. We have characterized a tandem duplication mutation within a COL1A1 allele of type I collagen from an infant with the lethal form of osteogenesis imperfecta. The structure of the mutation is consistent with the occurrence of an unequal crossover within a 15 base pair region of sequence identity between exons 14 and 17 of the COL1A1 gene. The recombination produced a new 81 base pair 17/14 hybrid exon and complete duplication of exons 15 and 16. The sequence implies duplication of 60 amino acid residues within the triple helical domain with preservation of the Gly-X-Y repeat. These data suggest that a recombinational mechanism that explains the hypothetical evolutionary process is active in cells, but the lethal effect of this mutation raises questions about the role of these events in creating new structures for polymeric proteins. © 1993 Wiley-Liss, Inc. 相似文献
994.
Large-scale molecular and tissue microarray analysis of mesothelin expression in common human carcinomas 总被引:10,自引:0,他引:10
Frierson HF Moskaluk CA Powell SM Zhang H Cerilli LA Stoler MH Cathro H Hampton GM 《Human pathology》2003,34(6):605-609
The 40-kilodalton processed glycoprotein, mesothelin, is highly expressed in epithelial mesotheliomas and adenocarcinomas of the ovary (serous papillary) and pancreas, but its expression in a large series of other common carcinomas has not been completely explored. In the present study, we used oligonucleotide and tissue microarrays to profile the expression of the mesothelin gene (MSLN) and encoded protein, respectively. Among 150 carcinomas of multiple anatomic sites, we found the highest average expression of MSLN in serous carcinomas of the ovary and adenocarcinomas of the pancreas, consistent with previous reports, as well as measurable but less-striking expression in pulmonary, gastric/esophageal, and colorectal adenocarcinomas. On tissue microarrays containing 621 carcinomas derived from the same and additional sites as those profiled by gene expression, mesothelin immunoreactivity was highest in cancers of the ovary (serous papillary, endometrioid, and undifferentiated) and pancreas, with less frequent staining seen in adenocarcinomas of the endometrium, lung, and stomach/esophagus. Some immunopositivity was observed in 42% of pulmonary adenocarcinomas, including 18% that had >50% of tumor cells that were immunoreactive. Some 14% of breast and 30% of colorectal adenocarcinomas showed immunopositivity, but no case contained >50% tumor cells that were immunoreactive. Mesothelin was either entirely absent or present in <5% of carcinomas of the prostate, bladder/ureter, liver, kidney, and thyroid. Overall, we observed good concordance between the results obtained by oligonucleotide and tissue microarrays. This large study of the MSLN gene and protein expression in common carcinomas provides data for future investigations that evaluate the utility of mesothelin/megakaryocyte potentiating factor as a potential serum tumor marker or target of immunotoxin-based therapy in human cancers. 相似文献
995.
996.
997.
BDNF increases release probability and the size of a rapidly recycling vesicle pool within rat hippocampal excitatory synapses 总被引:2,自引:1,他引:2
William J. Tyler Xiao-lei Zhang Kenichi Hartman Jochen Winterer Wolfgang Muller Patric K. Stanton Lucas Pozzo-Miller 《The Journal of physiology》2006,574(3):787-803
Exerting its actions pre-, post- and peri-synaptically, brain-derived neurotrophic factor (BDNF) is one of the most potent modulators of hippocampal synaptic function. Here, we examined the effects of BDNF on a rapidly recycling pool (RRP) of vesicles within excitatory synapses. First, we estimated vesicular release in hippocampal cultures by performing FM4-64 imaging in terminals impinging on enhanced green fluorescent protein (eGFP)-labelled dendritic spines – a hallmark of excitatory synapses. Consistent with a modulation of the RRP, BDNF increased the evoked destaining rate of FM4-64 only during the initial phase of field stimulation. Multiphoton microscopy in acute hippocampal slices confirmed these observations by selectively imaging the RRP, which was loaded with FM1-43 by hyperosmotic shock. Slices exposed to BDNF showed an increase in the evoked and spontaneous rates of FM1-43 destaining from terminals in CA1 stratum radiatum, mostly representing excitatory terminals of Schaffer collaterals. Variance-mean analysis of evoked EPSCs in CA1 pyramidal neurons further confirmed that release probability is increased in BDNF-treated slices, without changes in the number of independent release sites or average postsynaptic quantal amplitude. Because BDNF was absent during dye loading, imaging, destaining and whole-cell recordings, these results demonstrate that BDNF induces a long-lasting enhancement in the probability of transmitter release at hippocampal excitatory synapses by modulating the RRP. Since the endogenous BDNF scavenger TrkB-IgG prevented the enhancement of FM1-43 destaining rate caused by induction of long-term potentiation in acute hippocampal slices, the modulation of a rapidly recycling vesicle pool may underlie the role of BDNF in hippocampal long-term synaptic plasticity. 相似文献
998.
The effect of meptazinol in the spinal cord on carrageenan-induced hyperalgesia was investigated. The latency of paw withdrawal (PWL) to a thermal stimulus was used as an index of inflammatory hyperalgesia in awake rats. Intrathecal (i.t.) injection of 10 and 100 microg meptazinol markedly increased the PWL of the carrageenan-injected paw (P<0.01). The PWL of the non-injected paw was not detectably affected by the administration of meptazinol at the doses tested. I.t. injection of naloxone (5 microg) or atropine (1 microg) alone exhibited no effect on the PWLs of either the carrageenan-injected or non-injected paw. Pretreatment with naloxone, but not atropine, completely blocked the meptazinol-induced anti-hyperalgesia. These observations suggested that mu opioid receptor rather than muscarinic acetylcholine receptor may be involved in the anti-hyperalgesia of meptazinol in the spinal cord. 相似文献
999.
将HRP微电泳人黑尾蜡嘴雀(Eophona mihratoria)端脑原纹状体粗核内,观察其传入性纤维联系.在下列部位发现有密集的逆行标记细胞:(1):原纹状体带核;(2)上纹状体腹侧尾核;(3)新纹状体前部大细胞核外侧部;(4)脑桥蓝斑.以上标记细胞均出现在同侧.结果表明,原纹状体粗核接受原纹状体带核、上纹状体腹侧尾核、新纹状体前部大细胞核外侧部及脑桥蓝斑的传入性投射. 相似文献
1000.
Shao L Shinzawa H Zhang X Smith DB Watanabe H Mitsuhashi H Saito K Saito T Togashi H Takahashi T 《Virus genes》2000,21(3):215-221
The extent of population diversity among GB virus C (GBV-C)/hepatitis G virus (HGV) within a persistently infected individual (Iw) was investigated by sequence analysis of multiple clones generated from polymerase chain reaction (PCR)-amplified products of cDNA analogous to fragments of 5 non-coding region (5NC), envelope region 1/2 (E1/E2) and non-structural region 3 (NS3) of viral genome. Although nucleotide substitutions were more common in coding regions than in the 5NC region, there was no region corresponding to the hypervariable region of hepatitis C virus in the E1/E2 region. Transition substitution exceeded transversion by 7 to 12-fold, and 79.4% of substitutions were synonymous. This bias against substitutions producing amino acid replacements and the use of Pfu DNA polymerase with an error rate 10 times lower than the observed frequency of substitution, suggests that most substitutions were not artefactual. This data suggests that individual genomes of HGV within an infected individual may differ from each other at 0.23–0.84% nucleotide position and at 0.42–0.61% amino acid position. 相似文献