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Laid Douidah Lieven De Zutter Filip Van Nieuwerburgh Dieter Deforce Hanne Ingmer Olivier Vandenberg Anne-Marie Van den Abeele Kurt Houf 《PloS one》2014,9(1)
In this study, we report the screening of four Arcobacter species for the presence of small and large plasmids. Plasmids were present in 9.9% of the 273 examined strains. One Arcobacter cryaerophilus and four Arcobacter butzleri plasmids were selected for further sequencing. The size of three small plasmids isolated from A. butzleri and the one from A. cryaerophilus strains ranged between 4.8 and 5.1 kb, and the size of the large plasmid, isolated from A. butzleri, was 27.4 kbp. The G+C content of all plasmids ranged between 25.4% and 26.2%. A total of 95% of the large plasmid sequence represents coding information, which contrasts to the 20 to 30% for the small plasmids. Some of the open reading frames showed a high homology to putative conserved domains found in other related organisms, such as replication, mobilization and genes involved in type IV secretion system. The large plasmid carried 35 coding sequences, including seven genes in a contiguous region of 11.6 kbp that encodes an orthologous type IV secretion system found in the Wolinella succinogenes genome, Helicobacter pylori and Campylobacter jejuni plasmids, which makes this plasmid interesting for further exploration. 相似文献
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Densities of Drosera intermedia were low in two studied habitats (10–25 ramets m−1 ), a path through a wet heath (short inundation in spring, low soil moisture in summer) and a pool edge (longlasting inundation, high soil moisture in summer). The low densities could be explained by the observed low recruitment and high adult mortality.
The low recruitment resulted from: (1) a high first year mortality of the large number of seedlings that emerged each year in the path population, caused by summer drought and cover with algae after heavy rainfall; (2) the absence in two years out of three of seedling emergence at the pool edge, due to the longlasting inundation. In neither population any seedlings survived to flower; (3) low vegetative reproduction rate.
Adult mortality during the growing season was caused by drought, which did not occur at the pool edge. Rapid senescence in autumn, caused by summer drought on the path and by a rapid submersion after heavy rainfall at the pool edge, was associated with a high winter mortality. 相似文献
The low recruitment resulted from: (1) a high first year mortality of the large number of seedlings that emerged each year in the path population, caused by summer drought and cover with algae after heavy rainfall; (2) the absence in two years out of three of seedling emergence at the pool edge, due to the longlasting inundation. In neither population any seedlings survived to flower; (3) low vegetative reproduction rate.
Adult mortality during the growing season was caused by drought, which did not occur at the pool edge. Rapid senescence in autumn, caused by summer drought on the path and by a rapid submersion after heavy rainfall at the pool edge, was associated with a high winter mortality. 相似文献
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The reproductive behaviour of the longleaved sundew Drosera intermedia Hayne was studied in three hydrologically differing heathland habitats a pool edge, an old path through the wet heath and a seepage area
Sexual reproductive allocation (SRA) (the slope of the regression of sexual biomass on vegetative biomass m a given season) differed strongly between years (related to temperature and precipitation) and habitats Averaged over years, path plants had a higher SRA than plants in the seepage area and at the pool edge
Asexual reproductive allocation, expressed as the size-dependent probability of reproducing asexually, did not differ between habitats in most years
The observations agreed with general life history theory SRA was high in the path habitat where adult survival chances were low and juvenile (= seed, first year seedling) survival was high SRA was lower in the seepage area where adult survival chances were higher and juvenile survival lower At the pool edge, a habitat with high adult mortality and low juvenile establishment, the predicted optimal reproductive behaviour, a high SRA, was not observed due to environmental constraints (inundation) 相似文献
Sexual reproductive allocation (SRA) (the slope of the regression of sexual biomass on vegetative biomass m a given season) differed strongly between years (related to temperature and precipitation) and habitats Averaged over years, path plants had a higher SRA than plants in the seepage area and at the pool edge
Asexual reproductive allocation, expressed as the size-dependent probability of reproducing asexually, did not differ between habitats in most years
The observations agreed with general life history theory SRA was high in the path habitat where adult survival chances were low and juvenile (= seed, first year seedling) survival was high SRA was lower in the seepage area where adult survival chances were higher and juvenile survival lower At the pool edge, a habitat with high adult mortality and low juvenile establishment, the predicted optimal reproductive behaviour, a high SRA, was not observed due to environmental constraints (inundation) 相似文献
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Mateusz Okrutniak Irena M. Grześ Anna K. Kucharska Filip Turza Małgorzata Zimocha Sabrina Kerdiane Patryk Jabłoński 《Entomological Science》2023,26(3):e12549
In ants, workers of different sizes may perform various tasks, even in so-called monomorphic species with relatively low body size variation. However, it is unclear if the body size diversity of monomorphic workers correlates with task efficiency, especially in stressful contingencies. Here we tested if the body size variation of workers corresponds with its efficiency in transferring pupae. Transferring brood is a pre-set behavioral response to stress, e.g. suboptimal temperature. Here we applied a laboratory experiment simulating nest damage. The study was performed on the common garden ant (Lasius niger (Linnaeus, 1758)) – a species with no distinct worker subcastes. The efficiency of workers was measured as the latency of transferring pupae from a lit part of the experimental colony to a darkened part, while the body size diversity was expressed as the within-colony coefficient of variation in head width. We did not find any significant correlation between efficiency and body size variation. Summarizing the existing studies and the present results, we propose the hypothesis that the body size diversity of L. niger may have implications for workers’ division of labor but not for their task efficiency in a stressful contingency. 相似文献
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Rab17 Regulates Membrane Trafficking through Apical Recycling Endosomes in Polarized Epithelial Cells 总被引:6,自引:0,他引:6
Paola Zacchi Harald Stenmark Robert G. Parton Donata Orioli Filip Lim Angelika Giner Ira Mellman Marino Zerial Carol Murphy 《The Journal of cell biology》1998,140(5):1039-1053
A key feature of polarized epithelial cells is the ability to maintain the specific biochemical composition of the apical and basolateral plasma membrane domains while selectively allowing transport of proteins and lipids from one pole to the opposite by transcytosis. The small GTPase, rab17, a member of the rab family of regulators of intracellular transport, is specifically induced during cell polarization in the developing kidney. We here examined its intracellular distribution and function in both nonpolarized and polarized cells. By confocal immunofluorescence microscopy, rab17 colocalized with internalized transferrin in the perinuclear recycling endosome of BHK-21 cells. In polarized Eph4 cells, rab17 associated with the apical recycling endosome that has been implicated in recycling and transcytosis. The localization of rab17, therefore, strengthens the proposed homology between this compartment and the recycling endosome of nonpolarized cells. Basolateral to apical transport of two membrane-bound markers, the transferrin receptor and the FcLR 5-27 chimeric receptor, was specifically increased in Eph4 cells expressing rab17 mutants defective in either GTP binding or hydrolysis. Furthermore, the mutant proteins stimulated apical recycling of FcLR 5-27. These results support a role for rab17 in regulating traffic through the apical recycling endosome, suggesting a function in polarized sorting in epithelial cells. 相似文献
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Trimethylamine N-oxide (TMAO) is a naturally occurring osmolyte that stabilizes proteins, induces folding, and counteracts the denaturing effects of urea, pressure, and ice. To establish the mechanism behind these effects, isotopic substitution neutron-scattering measurements were performed on aqueous solutions of TMAO and 1:1 TMAO-urea at a solute mole fraction of 0.05. The partial pair distribution functions were extracted using the empirical potential structure refinement method. The results were compared with previous results obtained with isosteric tert-butanol, as well as the available data from spectroscopy and molecular-dynamics simulations. In solution, the oxygen atom of TMAO is strongly hydrogen-bonded to, on average, between two and three water molecules, and the hydrogen-bond network is tighter in water than in pure water. In TMAO-urea solutions, the oxygen atom in TMAO preferentially forms hydrogen bonds with urea. This explains why the counteraction is completed at a 2:1 urea/TMAO concentration ratio, independently of urea concentration. These results strongly support models for the effect of TMAO on the stability of proteins based on a modification of the simultaneous equilibria that control hydrogen bonding between the peptide backbone and water or intramolecular sites, without any need for direct interaction between TMAO and the protein. 相似文献