| 1. |
- Stöckl, Anna, et al.
(författare)
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Encoding of social signals in all three electrosensory pathways of Eigenmannia virescens.
- 2014
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Ingår i: Journal of Neurophysiology. - : American Physiological Society. - 0022-3077 .- 1522-1598. ; 112:9, s. 2076-2091
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Tidskriftsartikel (refereegranskat)abstract
- Extracting complementary features in parallel pathways is a widely used strategy for a robust representation of sensory signals. Weakly electric fish offer the rare opportunity to study complementary encoding of social signals in all of its electrosensory pathways. Electrosensory information is conveyed in three parallel pathways: two receptor types of the tuberous (active) system and one receptor type of the ampullary (passive) system. Modulations of the fish's own electric field are sensed by these receptors and used in navigation, prey-detection and communication. We studied the neuronal representation of electric communication signals (called chirps) in the ampullary and the two tuberous pathways of Eigenmannia virescens. We first characterized different kinds of chirps observed in behavioral experiments. Since Eigenmannia chirps simultaneously drive all three types of receptors, we studied their responses in in vivo electrophysiological recordings. Our results demonstrate that different electroreceptor types encode different aspects of the stimuli and each appears best suited to convey information about a certain chirp type. A decoding analysis of single neurons and small populations shows that this specialization leads to a complementary representation of information in the tuberous and ampullary receptors. This suggests that a potential readout mechanism should combine information provided by the parallel processing streams to improve chirp detectability.
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| 2. |
- Beranová, Lenka, et al.
(författare)
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Effect of heavy water on phospholipid membranes : experimental confirmation of molecular dynamics simulations
- 2012
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Ingår i: Physical Chemistry, Chemical Physics - PCCP. - : Royal Society of Chemistry. - 1463-9076 .- 1463-9084. ; 14:42, s. 14516-14522
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Tidskriftsartikel (refereegranskat)abstract
- Although there were experimental indications that phospholipid bilayers hydrated with D(2)O express different biophysical properties compared with hydration by ordinary H(2)O, a molecular concept for this behavior difference was only recently proposed by a molecular dynamics simulations study [T. Róg et al., J. Phys. Chem. B, 2009, 113, 2378-2387]. Here we attempt to verify those theoretical predictions by fluorescence measurements on 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) and 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) membranes. Specifically, we determine the water isotope effect on headgroup hydration and mobility, lateral lipid diffusion and lipid backbone packing. Time-dependent fluorescence shift experiments show significantly slower dynamics and lower hydration of the headgroup region for a bilayer hydrated with D(2)O, an observation in good agreement with the calculated predicted differences in duration of lipid-lipid and lipid-water bridges and extent of water penetration into the bilayer, respectively. The water isotope effect on the lipid order parameter of the bilayer core (measured by fluorescence anisotropy) and lateral diffusion of lipid molecules (determined by two-focus fluorescence correlation spectroscopy) is close to the experimental errors of the experiments, however also refers to slightly more rigid organization of phospholipid bilayers in heavy water. This study confirms the view that the water isotope effect can be particularly found in time-resolved physicochemical properties of the membrane. Together with the simulations our experiments provide a comprehensive, molecular view on the effect of D(2)O on phospholipid bilayers.
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| 3. |
- Blahut, Jan, et al.
(författare)
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Proton-detected fast-magic-angle spinning NMR of paramagnetic inorganic solids
- 2021
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Ingår i: RSC Advances. - : Royal Society of Chemistry (RSC). - 2046-2069. ; 11:47, s. 29870-29876
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Tidskriftsartikel (refereegranskat)abstract
- Fast (60 kHz) magic angle spinning solid-state NMR allows very sensitive proton detection in highly paramagnetic organometallic powders. We showcase this technique with the complete assignment of H-1 and C-13 resonances in a high-spin Fe(ii) polymerisation catalyst with less than 2 mg of sample at natural abundance.
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| 4. |
- Šoltésová, Mária, 1984-, et al.
(författare)
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Determination of size of molecular clusters of ethanol by means of diffusion NMR and hydrodynamic calculations
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Microscopic structure of ethanol in liquid state is characterized as dynamic equilibrium of hydrogen bonded clusters of different sizes and topologies. We have developed a novel method for determination of average size of the clusters that combines measurement of diffusion coefficient by means of PFG NMR technique and hydrodynamic simulations. The approach includes the use of HydroNMR [de la Torre 2000] for small molecules, which is attained here by the calibration procedure using dilute solution of tetramethylsilane. It is thus possible to correlate the experimentally determined apparent hydrodynamic radius of ethanol with calculated hydrodynamic radii of the modeled clusters of different sizes. We found that average size of the clusters in 0.16 M solution of ethanol in hexane ranges from monomer above 300 K to hexamer below 200 K. The clusters in the case of 0.44 M are generally slightly larger – from average size of dimer at 320 K to heptamer below 210 K.
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