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排序方式: 共有323条查询结果,搜索用时 46 毫秒
61.
Drabek K van Ham M Stepanova T Draegestein K van Horssen R Sayas CL Akhmanova A Ten Hagen T Smits R Fodde R Grosveld F Galjart N 《Current biology : CB》2006,16(22):2259-2264
In motile fibroblasts, stable microtubules (MTs) are oriented toward the leading edge of cells. How these polarized MT arrays are established and maintained, and the cellular processes they control, have been the subject of many investigations. Several MT "plus-end-tracking proteins," or +TIPs, have been proposed to regulate selective MT stabilization, including the CLASPs, a complex of CLIP-170, IQGAP1, activated Cdc42 or Rac1, a complex of APC, EB1, and mDia1, and the actin-MT crosslinking factor ACF7. By using mouse embryonic fibroblasts (MEFs) in a wound-healing assay, we show here that CLASP2 is required for the formation of a stable, polarized MT array but that CLIP-170 and an APC-EB1 interaction are not essential. Persistent motility is also hampered in CLASP2-deficient MEFs. We find that ACF7 regulates cortical CLASP localization in HeLa cells, indicating it acts upstream of CLASP2. Fluorescence-based approaches show that GFP-CLASP2 is immobilized in a bimodal manner in regions near cell edges. Our results suggest that the regional immobilization of CLASP2 allows MT stabilization and promotes directionally persistent motility in fibroblasts. 相似文献
62.
Komenda J Barker M Kuviková S de Vries R Mullineaux CW Tichy M Nixon PJ 《The Journal of biological chemistry》2006,281(2):1145-1151
The cyanobacterium Synechocystis sp. PCC 6803 contains four members of the FtsH protease family. One of these, FtsH (slr0228), has been implicated recently in the repair of photodamaged photosystem II (PSII) complexes. We have demonstrated here, using a combination of blue native PAGE, radiolabeling, and immunoblotting, that FtsH (slr0228) is required for selective replacement of the D1 reaction center subunit in both wild type PSII complexes and in PSII subcomplexes lacking the PSII chlorophyll a-binding subunit CP43. To test whether FtsH (slr0228) has a more general role in protein quality control in vivo, we have studied the synthesis and degradation of PSII subunits in wild type and in defined insertion and missense mutants incapable of proper assembly of the PSII holoenzyme. We discovered that, when the gene encoding FtsH (slr0228) was disrupted in these strains, the overall level of assembly intermediates and unassembled PSII proteins markedly increased. Pulse-chase experiments showed that this was due to reduced rates of degradation in vivo. Importantly, analysis of epitope-tagged and green fluorescent protein-tagged strains revealed that slr0228 was present in the thylakoid and not the cytoplasmic membrane. Overall, our results show that FtsH (slr0228) plays an important role in controlling the removal of PSII subunits from the thylakoid membrane and is not restricted to selective D1 turnover. 相似文献
63.
A Single Oncogenic Enhancer Rearrangement Causes Concomitant EVI1 and GATA2 Deregulation in Leukemia
Stefan Gröschel Mathijs A. Sanders Remco Hoogenboezem Elzo de Wit Britta A.M. Bouwman Claudia Erpelinck Vincent H.J. van der Velden Marije Havermans Roberto Avellino Kirsten van Lom Elwin J. Rombouts Mark van Duin Konstanze Döhner H. Berna Beverloo James E. Bradner Hartmut Döhner Bob Löwenberg Peter J.M. Valk Eric M.J. Bindels Wouter de Laat Ruud Delwel 《Cell》2014
64.
65.
Hanne De Kort Katrien Vandepitte Hans Henrik Bruun Déborah Closset‐Kopp Olivier Honnay Joachim Mergeay 《Molecular ecology》2014,23(19):4709-4721
The adaptive potential of tree species to cope with climate change has important ecological and economic implications. Many temperate tree species experience a wide range of environmental conditions, suggesting high adaptability to new environmental conditions. We investigated adaptation to regional climate in the drought‐sensitive tree species Alnus glutinosa (Black alder), using a complementary approach that integrates genomic, phenotypic and landscape data. A total of 24 European populations were studied in a common garden and through landscape genomic approaches. Genotyping‐by‐sequencing was used to identify SNPs across the genome, resulting in 1990 SNPs. Although a relatively low percentage of putative adaptive SNPs was detected (2.86% outlier SNPs), we observed clear associations among outlier allele frequencies, temperature and plant traits. In line with the typical drought avoiding nature of A. glutinosa, leaf size varied according to a temperature gradient and significant associations with multiple outlier loci were observed, corroborating the ecological relevance of the observed outlier SNPs. Moreover, the lack of isolation by distance, the very low genetic differentiation among populations and the high intrapopulation genetic variation all support the notion that high gene exchange combined with strong environmental selection promotes adaptation to environmental cues. 相似文献
66.
Wessel Van Leeuwen Marc J. M. Hagendoorn Tom Ruttink Remco Van Poecke Linus H. W. Van Der Plas Alexander R. Van Der Krol 《Plant Molecular Biology Reporter》2000,18(2):143-144
The properties of the firefly luciferase (LUC) make it a very good nondestructive reporter to quantify and image transgene
promoter activity in plants. The short half-life of the LUC mRNA and protein, and the very limited regeneration of the LUC
protein after reacting with luciferin, enables monitoring of changes in gene activity with a high time resolution. However,
the ease at which luciferase activity is measuredin planta, using a light sensitive camera system (2D-luminometer), contrasts sharply with the complications that arise from interpreting
the results. A variegated pattern of luciferase activity, that is often observed inin planta measurements, might either be caused by differences in influx, availability of the substrates (luciferin, oxygen, ATP) or
by local differences in reporter gene activity. Here we tested the possible contribution of differences in the availability
of each substrate to the variegatedin planta luciferase activity, and we show whenin planta luciferase activity is measured under substrate equilibrium conditions and can be related to the promoter activity of the
reporter gene. Furthermore, we demonstrate the effects of protein stability, apparent half-life of luciferase activity, regeneration
of luciferase and pH on thein vivo andin vitro luciferase measurements. The combined results give the prerequisites for the correct utilisation of the luciferase reporter
system, especially forin vivo gene expression studies in plant research. 相似文献
67.
Twelve dead Steller sea lion pups ( Eumetopias jubatus ) aged 3-14 d were recovered from rookeries in Southeast Alaska. They had a wide range of body sizes and conditions (small to large and fat to no fat). The ability of calipers to estimate the thickness of their blubber layer was assessed with a set of skinfold calipers. Average error of measurement for skin and blubber thickness was an acceptable 5.4%, but the skin and blubber of the pups were highly compressible. Skinfold thickness increased with body mass but did not necessarily reflect the development of blubber, given that pups with no blubber also showed an increase in skinfold thickness with increases in body mass. Skinfold thickness of sea lion pups appears to predict body size better than it predicts blubber thickness, making it difficult if not impossible to develop a simple index of body condition or a calculation of percent body fat for Steller sea lion pups from skinfold caliper measurements. 相似文献
68.
Sequencing-based typing of MICA reveals 33 alleles: a study on linkage with classical HLA genes 总被引:1,自引:0,他引:1
69.
Restoration of Botshol (The Netherlands) by reduction of external nutrient load: Recovery of the Characean community 总被引:1,自引:0,他引:1
The formerly rich characean community in Botshol with six species of which the rareNitellopsis obtusa andChara hispida dominated at many sites, decreased to only two species,Chara globularis andC. connivens, in the period 1980–1988. The macrophyteNajas marina also remained at some sites, and the aquatic mossFontinalis antipyretica and the filamentous algaVaucheria dichotoma predominated at many sites. These phenomena may have been due to eutrophication by the inlet of polluted water. This process of eutrophication was stopped by restoration measures in 1989, resulting in a lower phosphorus concentration (ca. 0.024 mg l–1) and a higher water transparency. Immediately after these measures the Characeae community increased strongly in abundance and number of species. During the summer of 1990, and especially of 1991, a spectacular growth occurred ofChara connivens. Chara connivens was often accompanied byChara hispida. Other species with scattered occurrence wereChara aculeolata, C. aspera, C. contraria andC. Globularis. The reasons for the shift in dominance fromNitellopsis obtusa toChara connivens are discussed. One of the reasons may be the recent higher chloride content which is one of the consequences of the restoration measures. 相似文献
70.
The structure of lipophorin, isolated from hemolymph of the Colorado potato beetle, was investigated by differential scanning calorimetry (DSC) and small-angle X-ray scattering. The DSC heating curves of intact lipophorin showed endothermic peaks that were similar to peaks obtained with the hydrocarbon fraction isolated from this lipophorin. The observed peaks correlated with the transition of the hydrocarbons from an ordered into a more disordered state. Changes in structure of the lipophorin particles with increasing temperature were also observed by small-angle X-ray scattering studies. The structural organization of lipophorin was further elucidated by simulation analysis, using a three-layered symmetrical sphere as a model. These studies revealed that lipophorin from the Colorado potato beetle is a sphere with a maximum diameter of 175 A. The sphere is composed of three radially symmetrical layers of different electron densities. The outer layer (37.5-39.5 A in thickness) is composed of phospholipid, apolipophorin I, and part of apolipophorin II. The middle layer (5-10 A) contains diacylglycerol, the rest of apolipophorin II, and probably beta-carotene. The core of the particle (40-45 A) only contains hydrocarbons. This structure differs from another model, previously proposed for cockroach and locust lipophorins [Katagiri, C., Sato, M., & Tanaka N. (1987) J. Biol. Chem. 262, 15857-15861], in the small size of the middle layer. The volume of the middle layer correlated well with the low diacylglycerol content of this lipophorin. 相似文献