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排序方式: 共有83条查询结果,搜索用时 15 毫秒
11.
Peng H Soeller C Vigar N Kilmartin PA Cannell MB Bowmaker GA Cooney RP Travas-Sejdic J 《Biosensors & bioelectronics》2005,20(9):1821-1828
A simple and label-free electrochemical sensor for recognition of the DNA hybridization event was prepared based on a new functionalised conducting copolymer, poly[pyrrole-co-4-(3-pyrrolyl) butanoic acid]. This precursor copolymer can be easily electrodeposited on the electrode surface and shows high electroactivity in an aqueous medium. An amino-substituted oligonucleotide (ODN) probe was covalently grafted onto the surface of the copolymer in a one step procedure and tested on hybridization with complementary ODN segments. The cyclic voltammogram of ODN probe-modified copolymer showed very little change when incubated in presence of non-complementary ODN, while a significant, and reproducible, modification of the voltammogram was observed after addition of complementary ODN. The AC impedance spectrum showed an increased charge transfer resistance (Rct) and double layer capacitance of the sensor film after hybridisation. Sensors with thinner films showed higher sensitivity than thicker films, suggesting that hybridisation at or near the surface of the film produces a larger change in electrical properties than that within the body of the film. 相似文献
12.
Increasing sensitivity of Ca2+ spark detection in noisy images by application of a matched-filter object detection algorithm 下载免费PDF全文
Microscopic calcium (Ca2+) events (such as Ca2+ sparks) are an important area for study, as they help clarify the mechanism(s) underlying intracellular signaling. In the heart, Ca2+ sparks occur as a result of Ca2+ release from the sarcoendoplasmic reticulum, via ryanodine receptor channels. Measurement of Ca2+ spark properties can provide valuable information about the control of ryanodine receptor channel gating in situ, but requires high spatiotemporal resolution imaging, which produces noisy datasets that are problematic for spark detection. Automated detection algorithms may overcome visual detection bias, but missed and false-positive events can distort the distribution of measured Ca2+ spark properties. We present a sensitive and reliable method for the automated detection of Ca2+ sparks in datasets obtained using confocal line-scanning or total internal reflection fluorescence microscopy. This matched-filter detection algorithm (MFDA) employs a user-defined object, chosen to mimic Ca2+ spark properties, and the experimental dataset is searched for instances of the object. Detection certainty is provided by nonparametric statistical testing. The supplied codes can also refine the search object on the basis of those detected to further increase detection sensitivity. In comparison to a commonly used, intensity-thresholding algorithm, the MFDA is more sensitive and reliable, particularly at low signal/noise ratios. The MFDA can also be easily adapted to other signal-detection problems in noisy datasets. 相似文献
13.
Tissue electroporation was applied to a member of the Triticeae family, namely tritordeum (Hordeum chilense Roem.×Triticum turgidum L. Conv. durum), for the generation of fertile transgenic plants. Two transgenic plants were recovered following the treatment of 361 explants
of immature inflorescences (although they were subsequently found to result from the same transformation event). The expression
of both inserted marker genes (uidA and bar) was confirmed using standard assays, while transgene integration was confirmed using PCR and Southern hybridization analyses.
Integration pattern, segregation ratio and the inheritance of transgene expression in T1 progeny were consistent for the presence of a single transgene locus containing five to ten plasmid insertions. Although
this procedure has been applied to other cereal species, stable transformation of the Triticeae using tissue electroporation
has not previously been reported.
Received: 28 October 1999 / Revision received: 25 August 2000 / Accepted: 29 August 2000 相似文献
14.
A system for barley transformation via polyethyleneglycol-mediated DNA uptake into protoplasts isolated directly from scutella
and the regeneration of transgenic plants is reported. Scutellum protoplasts (cv. Clipper, an Australian malting cultivar)
were co-transformed with plasmids Act 1-DGUS, containing the marker uidA gene, and pCaIneo, which contains the selectable marker neomycin phosphotransferase gene. Protoplast-derived calluses were
selected on medium containing the antibiotic G418 (25 and 15 mg.l–1) and macroscopic antibiotic resistant colonies were recovered. Fertile plants were regenerated from a callus line and molecular
analysis confirmed transgene integration.
Received: 11 October 1999 / Revision received: 11 February 2000 / Accepted: 11 February 2000 相似文献
15.
Glycosidase inhibitors from algae 总被引:1,自引:0,他引:1
J S Winder R J Cannell J M Walker S Delbarre C Francisco P B Farmer 《Biochemical Society transactions》1989,17(6):1030-1031
16.
Martin E. Cannell Alison J. Mitchell Sharon McCready James A. Callow Jonathan R. Green 《Plant molecular biology》1995,27(4):821-824
A monoclonal antibody (MAb UB42) is described that binds to thylakoids in pea chloroplasts, as shown by EM-immunogold labelling. The antibody recognised proteins of ca. 23–29 kDa in western blots of a pea leaf homogenate. A cDNA library was prepared from pea epidermal cells in the vector ZAP II, and immunoscreening of the library with UB42 led to the isolation of a clone, pUB42. This was sequenced and had an open reading frame of 269 codons encoding a predicted polypeptide of 28.9 kDa. The sequence showed extensive homology with three closely related polypeptides belonging to a family of chlorophyll a/b-binding proteins from the light harvesting complex of photosytem I (LHCI). Collectively, the results suggest that MAb UB42 recognises an epitope on the type II chlorophyll a/b-binding protein from LHCI and that clone pUB42 encodes this protein. 相似文献
17.
18.
Setiawan AN Davis LS Darby JT Lokman PM Young G Blackberry MA Cannell BL Martin GB 《Comparative biochemistry and physiology. Part A, Molecular & integrative physiology》2006,145(3):357-362
Penguins show varying degrees of brood reduction behavior, from obligate brood reducers to brood maximizers, and we hypothesize that this is associated with differences in prolactin secretion. To address this hypothesis, we determined the breeding season prolactin profile of the yellow-eyed penguin (Megadyptes antipodes) for comparison with those of other penguin species found in the literature. We also measured sex steroid plasma concentrations to better characterize the reproductive cycle of the species. Plasma concentrations of prolactin increased from early in the season, reaching a peak during late incubation, and remained elevated up to the guard period. This general pattern was similar to that of other penguins for which we have corresponding data. However, we found that throughout the laying period, prolactin titers in yellow-eyed penguins remained elevated while they fell to basal levels after the laying of the first egg in macaroni penguins, which corresponds to differences in incubation behavior during this time. We conclude, therefore, that differences in the brood reduction behavior in penguins, may be reflected in the pattern of PRL concentrations around the time of egg laying. 相似文献
19.
20.
Spatial non-uniformities in [Ca2+]i during excitation-contraction coupling in cardiac myocytes. 总被引:15,自引:8,他引:7 下载免费PDF全文
The intracellular calcium ([Ca2+]i) transient in adult rat heart cells was examined using the fluorescent calcium indicator fluo-3 and a laser scanning confocal microscope. We find that the electrically evoked [Ca2+]i transient does not rise at a uniform rate at all points within the cell during the [Ca2+]i transient. These spatial non-uniformities in [Ca2+]i are observed immediately upon depolarization and largely disappear by the time the peak of the [Ca2+]i transient occurs. Importantly, some of the spatial non-uniformity in [Ca2+]i varies randomly in location from beat to beat. Analysis of the spatial character of the non-uniformities suggests that they arise from the stochastic nature of the activation of SR calcium-release channels. The non-uniformities in [Ca2+]i are markedly enhanced by low concentrations of Cd2+, suggesting that activation of L-type calcium channels is the primary source of activator calcium for the calcium transient. In addition, the pattern of calcium release in these conditions was very similar to the spontaneous calcium sparks that are observed under resting conditions and which are due to spontaneous calcium release from the SR. The spatial non-uniformity in the evoked [Ca2+]i transient under normal conditions can be explained by the temporal and spatial summation of a large number of calcium sparks whose activation is a stochastic process. The results are discussed with respect to a stochastic local control model for excitation-contraction (E-C) coupling, and it is proposed that the fundamental unit of E-C coupling consists of one dihydropyridine receptor activating a small group of ryanodine receptors (possibly four) in a square packing model. 相似文献