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排序方式: 共有206条查询结果,搜索用时 203 毫秒
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Raiz J Damert A Chira S Held U Klawitter S Hamdorf M Löwer J Strätling WH Löwer R Schumann GG 《Nucleic acids research》2012,40(4):1666-1683
SINE-VNTR-Alu (SVA) elements are non-autonomous, hominid-specific non-LTR retrotransposons and distinguished by their organization as composite mobile elements. They represent the evolutionarily youngest, currently active family of human non-LTR retrotransposons, and sporadically generate disease-causing insertions. Since preexisting, genomic SVA sequences are characterized by structural hallmarks of Long Interspersed Elements 1 (LINE-1, L1)-mediated retrotransposition, it has been hypothesized for several years that SVA elements are mobilized by the L1 protein machinery in trans. To test this hypothesis, we developed an SVA retrotransposition reporter assay in cell culture using three different human-specific SVA reporter elements. We demonstrate that SVA elements are mobilized in HeLa cells only in the presence of both L1-encoded proteins, ORF1p and ORF2p. SVA trans-mobilization rates exceeded pseudogene formation frequencies by 12- to 300-fold in HeLa-HA cells, indicating that SVA elements represent a preferred substrate for L1 proteins. Acquisition of an AluSp element increased the trans-mobilization frequency of the SVA reporter element by ~25-fold. Deletion of (CCCTCT)(n) repeats and Alu-like region of a canonical SVA reporter element caused significant attenuation of the SVA trans-mobilization rate. SVA de novo insertions were predominantly full-length, occurred preferentially in G+C-rich regions, and displayed all features of L1-mediated retrotransposition which are also observed in preexisting genomic SVA insertions. 相似文献
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Beale TM Bond PJ Brenton JD Charnock-Jones DS Ley SV Myers RM 《Bioorganic & medicinal chemistry》2012,20(5):1749-1759
The antiproliferative activity on ovarian cancer (SK-OV-3) cells of a series of triazole-bridged combretastatin analogues (37, 38, 40-43) containing dihalogenation of the A-ring is reported, and compared with their trimethoxy analogues (5, 15, 39). It was found that dihalogenation with either bromine or iodine was a tolerated modification when compared to the parent compound combretastatin (CA-4, 1) and had less effect than B-ring modification on potency. These compounds exhibited G(2)/M arrest, and maintained antitubulin activity. Further assays on human umbilical vein endothelial cells (HUVECs) demonstrated the potential antivascular effects of these triazoles. Of particular note was a 3,5-diiodo-4-methoxyaryl triazole (43) which had promising 7-fold selectivity for HUVECs over ovarian cancer cells. 相似文献
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James I. Langridge A. Gareth Brenton Terry J. Walton Frank M. Harris Russell P. Newton 《Nucleosides, nucleotides & nucleic acids》2013,32(3-5):739-742
Abstract Fast atom bombardment mass spectrometry in concert with collisionally-induced dissociation and mass-analysed kinetic energy spectrum scanning has enabled unequivocal identification of putative cyclic nucleotides in tissue extracts; quantitative analyses have enabled kinetic studies of cyclic nucleotide-related enzymes with multi-component monitoring, and dynamic spectrometric systems provide a potential means of continuous assay for these enzymes. 相似文献
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Kurt Hamdorf Gerd Rosner 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1973,86(3):281-292
Zusammenfassung Adaptationsversuche mit quantengleichen monochromatischen Lichtern zeigen, daß die Empfindlichkeit der Miegenretina 3 min nach monochromatischer Helladaptation annähernd proportional der Sehfarbstoffkonzentration in den Rezeptoren ist. Spektralphotometrisch wurde nachgewiesen, daß während der Helladaptation sich photochemische Gleichgewichte zwischen dem Sehpigment P 490–500 und einem thermostabilen Folgefarbstoff M 550–560 einstellen.
Mit Unterstützung der Deutschen Forschungsgemeinschaft im Rahmen des Schwerpunktsprogramms Rezeptorphysiologie und SFB-114. — Die Meßdaten der Abb. 3 stellte freundlicherweise Dr. J. Schwemer zur Verfügung. 相似文献
Adaptation and photoregeneration in the eye of the blow fly
Summary Adaptation with equal quanta monochromatic lights causes in the photoreceptors of the blow flyCalliphora three minutes after cessation in darkness an increase of threshold up to a level which is nearly proportional to the concentration of visual pigment P 490–500. Photometric measurements have shown that monochromatic illumination causes a photoequilibrium between visual pigment P 490–500 and its thermostable Metarhodopsin M 550–560.
Mit Unterstützung der Deutschen Forschungsgemeinschaft im Rahmen des Schwerpunktsprogramms Rezeptorphysiologie und SFB-114. — Die Meßdaten der Abb. 3 stellte freundlicherweise Dr. J. Schwemer zur Verfügung. 相似文献
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Summary A family of genes expressed during early stages of shoot development were isolated fromPinus radiata. A homologue of theLEAFY/FLORICAULA flower meristem-identity genes,NEEDLY (NLY), and three MADS-box genes,PrMADS1, PrMADS2 andPrMADS3 (Pinus radiata MADS-box genes), were expressed at early stages of initiation and differentiation of reproductive (male and female) cone buds, as well as vegetative buds. Expression ofNLY in transgenicArabidopsis thaliana promoted floral fate, demonstrating that it encodes a functional ortholog of theFLORICAUL A/LEAFY genes of angiosperms.Abbreviations DSB
dwarf shoot bud
- LSTB
long-shoot terminal bud
- PCB
pollen cone bud
- SCB
seed cone bud
- LD
long day
- SD
short day 相似文献
30.
P. Stušek K. Hamdorf 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1999,184(1):99-106
Regulation of light flux by pupil mechanisms in the UV-sensitive superposition eye of owl-fly Ascalaphus macaronius (Neuroptera) was studied with a fast reflection microspectrophotometric technique. The spectral sensitivity of pupil reaction,
which was calculated on the basis of changes of transient amplitude reflection, was almost identical with the one of Deilephila eye. This indicates that in spite of different life styles and spectral sensitivities of photoreceptors, pupil closing is
triggered by the same photosensitive structure in both eyes. By measuring the spectra of reflected light from the Ascalaphus eye between 400 and 700 nm after different dark periods following light stimulation, it was established that the restoration
of reflection was much faster in the red than in the blue spectral range. Based on this, we propose that two different pupil
mechanisms with different spectral absorption characteristics are involved in light-flux regulation. Fast-reacting pupil is
probably represented by screening pigment migration in the secondary pigment cells and a slow blue-absorbing system by the
activity in primary pigment cells. The importance of two different pupils for the photoregeneration of visual pigment is discussed.
Accepted: 1 October 1998 相似文献