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561.
562.
Jaimey D. Tucker C. Alistair Siebert Maryana Escalante Peter G. Adams John D. Olsen Cees Otto David L. Stokes C. Neil Hunter 《Molecular microbiology》2010,76(4):833-847
The purple phototrophic bacteria synthesize an extensive system of intracytoplasmic membranes (ICM) in order to increase the surface area for absorbing and utilizing solar energy. Rhodobacter sphaeroides cells contain curved membrane invaginations. In order to study the biogenesis of ICM in this bacterium mature (ICM) and precursor (upper pigmented band – UPB) membranes were purified and compared at the single membrane level using electron, atomic force and fluorescence microscopy, revealing fundamental differences in their morphology, protein organization and function. Cryo‐electron tomography demonstrates the complexity of the ICM of Rba. sphaeroides. Some ICM vesicles have no connection with other structures, others are found nearer to the cytoplasmic membrane (CM), often forming interconnected structures that retain a connection to the CM, and possibly having access to the periplasmic space. Near‐spherical single invaginations are also observed, still attached to the CM by a ‘neck’. Small indents of the CM are also seen, which are proposed to give rise to the UPB precursor membranes upon cell disruption. ‘Free‐living’ ICM vesicles, which possess all the machinery for converting light energy into ATP, can be regarded as bacterial membrane organelles. 相似文献
563.
564.
Krijn Baptist Trimbos Joyce Broekman Rosemarie Kentie Cees J. M. Musters Geert R. de Snoo 《Journal of Ornithology》2009,150(4):915-920
In the context of population genetic research, a faster and less invasive method of DNA sampling would allow large-scale assessments
of genetic diversity and genetic differentiation with the help of volunteer observers. The aim of this study was to investigate
the usefulness of eggshell membranes as a DNA source for population genetic research, by addressing eggshell membrane DNA
quality, degeneration and cross-contamination. To this end, a comparison was made with blood-derived DNA samples. We have
demonstrated 100% successful DNA extraction from post-hatched Black-tailed Godwit (Limosa limosa) eggshell membranes as well as from blood samples. Using 11 microsatellite loci, DNA amplification success was 99.1% for
eggshell membranes and 97.7% for blood samples. Genetic information within eggshell membrane DNA in comparison to blood DNA
was not affected (F
ST = −0.01735, P = 0.999) by degeneration or possible cross-contamination. Furthermore, neither degeneration nor cross-contamination was apparent
in total genotypic comparison of eggshell membrane DNA and blood sample DNA. Our research clearly illustrates that eggshell
membranes can be used for population genetic research. 相似文献
565.
Cees J. N. Buisman Alfons J. M. Stams Hans Meijer Gatze Lettinga 《Applied microbiology and biotechnology》1989,32(3):363-370
Summary Sulphide production rates of sulphur-and sulphate-reducing bacteria up to 50 mg per biomass support particle per day were observed in an aerated sulphide-removal reactor with polyurethane (PUR) foam as carrier material. The optimal pH and temperature for the sulphide-producing bacteria were 8.0 and 30°C respectively. Raschig rings and four types of cube-shaped PUR particles were tested as carrier materials. When using PUR particles, the sulphide production rate was always between 3% and 4% of the sulphide removal rate, dependent on the dimensions and pore size of the polyurethane support particles. With the Raschig rings this ratio was only 2% and for reactors in which no carrier materials were present it was even lower (0.6%). Media containing different mixtures of acetate, propionate, sulphur and sulphate inoculated under anoxic conditions with sludge from the aerated reactor showed the presence of acetate-degrading sulphur-reducing, but not of acetate-degrading sulphate-reducing, bacteria. With propionate as sole electron donor no degradation occurred in the presence of sulphur within 2 weeks, whereas sulphate-dependent propionate oxidation started after 5–6 days incubation. Bacteria were isolated and resembled Desulfuromonas acetoxidans and Desulfobulbus propionicus morphologically and physiologically. 相似文献
566.
Results from previous studies suggest that sucrose and NaClsolutions have an equal perceived taste intensity when the molarconcentration of sucrose is 1.51.75 times the molar concentrationof NaCl. However, according to other studies, sucrose and NaClsolutions taste equally strong when their molar concentrationsare about equal. This issue was further pursued using the methodof constant stimuli, where subjects matched the perceived tasteintensity of NaCl solutions to five sucrose references and viceversa. The results concur with previous findings that sucroseand NaCl solutions have equal perceived taste intensities whenthe molar concentration of sucrose is 1.51.75 times themolar concentration of NaCl. 相似文献
567.
568.
Cees Haringa 《Engineering in Life Science》2023,23(1):e2100159
Euler-Lagrange CFD simulations, where the biotic phase is represented by computational particles (parcels), provide information on environmental gradients inside bioreactors from the microbial perspective. Such information is highly relevant for reactor scale-down and process optimization. One of the major challenges is the computational intensity of CFD simulations, especially when resolution of dynamics in the flowfield is required. Lattice-Boltzmann large-eddy simulations (LB-LES) form a very promising approach for simulating accurate, dynamic flowfields in stirred reactors, at strongly reduced computation times compared to finite volume approaches. In this work, the performance of LB-LES in resolving substrate gradients in large-scale bioreactors is explored, combined with the inclusion of a Lagrangian biotic phase to provide the microbial perspective. In addition, the hydrodynamic performance of the simulations is confirmed by verification of hydrodynamic characteristics (radial velocity, turbulent kinetic energy, energy dissipation) in the impeller discharge stream of a 29 cm diameter stirred tank. The results are compared with prior finite volume simulation results, both in terms of hydrodynamic and biokinetic observations, and time requirements. 相似文献
569.
Hoi Fei Kwok Peter Jurica Antonino Raffone Cees van Leeuwen 《Cognitive neurodynamics》2007,1(1):39-51
Spontaneous activity in biological neural networks shows patterns of dynamic synchronization. We propose that these patterns
support the formation␣of a small-world structure—network connectivity␣optimal for distributed information processing. We␣present
numerical simulations with connected Hindmarsh–Rose neurons in which, starting from random connection distributions, small-world
networks evolve as a result of applying an adaptive rewiring rule. The rule connects pairs of neurons that tend fire in synchrony,
and disconnects ones that fail to synchronize. Repeated application of the rule leads to small-world structures. This mechanism
is robustly observed for bursting and irregular firing regimes. 相似文献