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排序方式: 共有97条查询结果,搜索用时 156 毫秒
1.
F. D. Miller K. F. Jorgenson R. J. Winkfein J. H. van de Sande D. A. Zarling J. Stockton 《Journal of biomolecular structure & dynamics》2013,31(3):611-620
Abstract Bacteriophage PM2 DNA, a ccc genome of high apparent superhelical density, contains left-handed (Z) regions as detected by competitive radioimmunoassay, agarose gel electrophoresis of DNA: antibody complexes and immunoelectron microscopy. The latter technique, in conjunction with partial blockage of restriction endonuclease sites by bound antibody, was used to map the left-handed regions along the DNA molecule. A cluster of four to five antibody molecules (approximately 25% of bound antibody) was located within map units 0.05–0.18 of the single Hpa II restriction site. Sequence analysis of part of this region showed the presence of several areas of high alternating purine-pyrimidine content. A strong correlation is observed between alternating pyrimidine-purine tracts of significant length and antibody binding sites. 相似文献
2.
Calcium activation of mougeotia potassium channels 总被引:1,自引:1,他引:0
Phytochrome mediates chloroplast movement in the alga Mougeotia, possibly via changes in cytosolic calcium. It is known to regulate a calcium-activated potassium channel in the algal plasma membrane. As part of a characterization of the potassium channel, we examined the properties of calcium activation. The calcium ionophore A23187 activates the channel at external [Ca(2+)] as low as 20 micromolar. However, external [Ca(2+)] is not required for activation of the channel by photoactivated phytochrome. Furthermore, when an inhibitor of calcium release from internal stores, 8-(diethylamino)-octyl-3,4,5-trimethoxybenzoate, hydrochloride (TMB-8), is present, red light no longer stimulates channel activity. We conclude that phytochrome activates the plasma membrane potassium channel by releasing calcium from intracellular calcium vesicles; the elevated cytosolic calcium then stimulates channel activity by an unknown mechanism. In the presence of TMB-8, red light does induce chloroplast rotation; thus, potassium channel activation may not be coupled to chloroplast rotation. 相似文献
3.
4.
G W Stockton K G Johnson K W Butler C F Polnaszek R Cyr I C Smith 《Biochimica et biophysica acta》1975,401(3):535-539
The first application of deuterium magentic resonance of specifically labelled lipids to the study of a natural biological membrane is described. Palmitic acid labelled at the terminal methyl group with deuterium was incorporated biosynthetically into the lipids of the plasma membrane of Acholeplasma laidlawii. The deuterium nuclear magnetic resonance spectra contain quadrupole splittings which yield directly order parameters for this region of the membrane. Below the growth temperature (37 degrees C) the spectra are indicative of lipid in both gel and liquid crystalline states. Above this temperature they demonstrate the existence of an entirely liquid crystalline membrane whose order parameter decreases rapidly with increasing temperature. Comparison with egg phosphatidylcholine over the same temperature range shows a more rapid change in order with temperature for the A. laidlawii membranes. 相似文献
5.
Stockton JC Howson JM Awomoyi AA McAdam KP Blackwell JM Newport MJ 《FEMS immunology and medical microbiology》2004,41(2):157-160
The nucleotide oligomerization binding domain 2 gene (NOD2) encodes an intracellular receptor for bacterial components, which is expressed in monocytes and is associated with Crohn's Disease (CD). This finding, along with epidemiological evidence, supports a role for infection in the pathogenesis of CD. Speculation that mycobacteria are involved in CD led us to investigate NOD2 in susceptibility to tuberculosis (TB), a global public health problem caused by Mycobacterium tuberculosis. CD-associated NOD2 variants were absent in a case-control study of 640 Gambians, where CD is rare. Novel NOD2 promoter polymorphisms were identified but showed no association with TB in this African population sample. 相似文献
6.
5-lipoxygenase and cyclooxygenase regulate wound closure in NIH/3T3 fibroblast monolayers 总被引:1,自引:0,他引:1
Green JA Stockton RA Johnson C Jacobson BS 《American journal of physiology. Cell physiology》2004,287(2):C373-C383
Wound healing involves multiple cell signaling pathways, including those regulating cell-extracellular matrix adhesion. Previous work demonstrated that arachidonate oxidation to leukotriene B4 (LTB4) by 5-lipoxygenase (5-LOX) signals fibroblast spreading on fibronectin, whereas cyclooxygenase-2 (COX-2)-catalyzed prostaglandin E2 (PGE2) formation facilitates subsequent cell migration. We investigated arachidonate metabolite signaling in wound closure of perturbed NIH/3T3 fibroblast monolayers. We found that during initial stages of wound closure (0120 min), all wound margin cells spread into the wound gap perpendicularly to the wound long axis. At regular intervals, between 120 and 300 min, some cells elongated to project across the wound and meet cells from the opposite margin, forming distinct cell bridges spanning the wound that act as foci for later wound-directed cell migration and resulting closure. 5-LOX inhibition by AA861 demonstrated a required LTB4 signal for initial marginal cell spreading and bridge formation, both of which must precede wound-directed cell migration. 5-LOX inhibition effects were reversible by exogenous LTB4. Conversely, COX inhibition by indomethacin reduced directed migration into the wound but enhanced early cell spreading and bridge formation. Exogenous PGE2 reversed this effect and increased cell migration into the wound. The differential effects of arachidonic acid metabolites produced by LOX and COX were further confirmed with NIH/3T3 fibroblast cell lines constitutively over- and underexpressing the 5-LOX and COX-2 enzymes. These data suggest that two competing oxidative enzymes in arachidonate metabolism, LOX and COX, differentially regulate sequential aspects of fibroblast wound closure in vitro. leukotriene B4; prostaglandin E2; spreading; migration; bridges 相似文献
7.
Feces from 15 dogs at 2 different foxhound kennels in the U.K. were examined microscopically for the presence of oocysts of Neospora caninum. One sample containing approximately 400 candidate oocysts per gram was positive in a polymerase chain reaction (PCR) using N. caninum-specific primers. In a sample taken 4 mo later from the same hound. N. caninum oocysts were again detected visually and by PCR. This is the third reported case of a dog naturally excreting oocysts of N. caninum and suggests that oocyst excretion can occur over a relatively long period of time in some circumstances or that reshedding may occur. 相似文献
8.
9.
Zhang W Amir R Stockton DW Van Den Veyver IB Bacino CA Zoghbi HY 《American journal of human genetics》2000,66(4):1461-1464
We have identified a four-generation family with 10 affected females manifesting one or more of the following features: osseous dysplasia involving the metacarpals, metatarsals, and phalanges leading to brachydactyly, camptodactyly, and other digital deformities; pigmentary defects on the face and scalp; and multiple frenula. There were no affected males. We performed X-inactivation studies on seven affected females, using a methylation assay at the androgen receptor locus; all seven demonstrated preferential inactivation of their maternal chromosomes carrying the mutation, and two unaffected females showed a random pattern. These findings indicate that this disorder is linked to the X chromosome. To map the gene for this disorder, we analyzed DNA from nine affected females and five unaffected individuals, using 40 polymorphic markers evenly distributed throughout the X chromosome. Two-point and multipoint linkage analyses using informative markers excluded most of the X chromosome and demonstrated linkage to a region on the long arm between DXS548 and Xqter. A maximum LOD score of 3.16 at recombination fraction 0 was obtained for five markers mapping to Xq27.3-Xq28. The mapping data should facilitate the identification of the molecular basis of this disorder. 相似文献
10.
Current status of antisense DNA methods in behavioral studies 总被引:4,自引:0,他引:4
The antisense DNA method has been used successfully to block the expression
of specific genes in vivo in neuronal systems. An increasing number of
studies in the last few years have shown that antisense DNA administered
directly into the brain can modify various kinds of behaviors. These
findings strongly suggest that the antisense DNA method can be used as a
powerful tool to study causal relationships between molecular processes in
the brain and behavior. In this article we review the current status of the
antisense method in behavioral studies and discuss its potentials and
problems by focusing on the following four aspects; (i) optimal application
paradigms of antisense DNA methods in behavioral studies; (ii) efficiencies
of different administration methods of antisense DNA used in behavioral
studies; (iii) determination of specificity of behavioral effects of
antisense DNA; and (iv) discrepancies between antisense DNA effects on
behaviors and those on protein levels of the targeted gene.
相似文献