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Search Results: 1 - 10 of 7099 matches for " Daniela Reichenbach "
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NOD2-C2 - a novel NOD2 isoform activating NF-κB in a muramyl dipeptide-independent manner
Marcel Kramer, Janne Boeck, Daniela Reichenbach, Christoph Kaether, Stefan Schreiber, Matthias Platzer, Philip Rosenstiel, Klaus Huse
BMC Research Notes , 2010, DOI: 10.1186/1756-0500-3-224
Abstract: Here, we report a novel alternative transcript of the NOD2 gene, which codes for a truncated tandem CARD only protein, called NOD2-C2. The transcript isoform is highest expressed in leucocytes, a natural barrier against pathogen invasion, and is strictly linked to promoter usage as well as predominantly to one allele of the single nucleotide polymorphism rs2067085. Contrary to a previously identified truncated single CARD NOD2 isoform, NOD2-S, NOD2-C2 is able to activate NF-κB in a dose dependent manner independently of muramyl dipeptide (MDP). On the other hand NOD2-C2 competes with MDPs ability to activate the NOD2-driven NF-κB signaling cascade.NOD2 transcripts having included an alternative exon downstream of exon 3 (exon 3a) are the endogenous equivalents of a previously described in vitro construct with the putative protein composed of only the two N-terminal CARDs. This protein form (NOD2-C2) activates NF-κB independent of an MDP stimulus and is a potential regulator of NOD2 signaling.The innate immune system uses several molecules that sense pathogen-associated molecular patterns (PAMPs) including Toll-like, RIG-1 (retinoic acid inducible gene protein 1)-like and the NOD (nucleotide-binding and oligomerization domain)-like receptors (NLRs) to trigger a protective response against intracellular danger signals, e.g. cytoinvasive pathogens. The NLRs family consists of more than 20 related members defined by a tripartite structure consisting of: (i) a variable N-terminal protein-protein interaction domain, defined by the caspase recruitment domain (CARD), pyrin domain (PYD), or the baculovirus inhibitor domain (BIR); (ii) a centrally located NOD domain facilitating self-oligomerization during activation [1], and (iii) a C-terminal leucine-rich repeat (LRR) responsible for binding/detecting of PAMPs. The N-terminal effector binding domains are essential elements of the NLRs to elicit a signal subsequent to NLR activation. In case of NOD1 and NOD2 (CARD15), the N-
Tissue-Specific and Minor Inter-Individual Variation in Imprinting of IGF2R Is a Common Feature of Bos taurus Concepti and Not Correlated with Fetal Weight
Daniela Bebbere, Stefan Bauersachs, Rainer W. Fürst, Horst-Dieter Reichenbach, Myriam Reichenbach, Ivica Medugorac, Susanne E. Ulbrich, Eckhard Wolf, Sergio Ledda, Stefan Hiendleder
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0059564
Abstract: The insulin-like growth factor 2 receptor (IGF2R) is essential for prenatal growth regulation and shows gene dosage effects on fetal weight that can be affected by in-vitro embryo culture. Imprinted maternal expression of murine Igf2r is well documented for all fetal tissues excluding brain, but polymorphic imprinting and biallelic expression were reported for IGF2R in human. These differences have been attributed to evolutionary changes correlated with specific reproductive strategies. However, data from species suitable for testing this hypothesis are lacking. The domestic cow (Bos taurus) carries a single conceptus with a similar gestation length as human. We identified 12 heterozygous concepti informative for imprinting studies among 68 Bos taurus fetuses at Day 80 of gestation (28% term) and found predominantly maternal IGF2R expression in all fetal tissues but brain, which escapes imprinting. Inter-individual variation in allelic expression bias, i.e. expression of the repressed paternal allele relative to the maternal allele, ranged from 4.6?8.9% in heart, 4.3?10.2% in kidney, 6.1?11.2% in liver, 4.6?15.8% in lung and 3.2?12.2% in skeletal muscle. Allelic bias for mesodermal tissues (heart, skeletal muscle) differed significantly (P<0.05) from endodermal tissues (liver, lung). The placenta showed partial imprinting with allelic bias of 22.9?34.7% and differed significantly (P<0.001) from all other tissues. Four informative fetuses were generated by in-vitro fertilization (IVF) with embryo culture and two individuals displayed fetal overgrowth. However, there was no evidence for changes in imprinting or DNA methylation after IVF, or correlations between allelic bias and fetal weight. In conclusion, imprinting of Bos taurus IGF2R is similar to mouse except in placenta, which could indicate an effect of reproductive strategy. Common minor inter-individual variation in allelic bias and absence of imprinting abnormalities in IVF fetuses suggest changes in IGF2R expression in overgrown fetuses could be modulated through other mechanisms than changes in imprinting.
Instability of spatial patterns and its ambiguous impact on species diversity
Tobias Reichenbach,Erwin Frey
Physics , 2008, DOI: 10.1103/PhysRevLett.101.058102
Abstract: Self-arrangement of individuals into spatial patterns often accompanies and promotes species diversity in ecological systems. Here, we investigate pattern formation arising from cyclic dominance of three species, operating near a bifurcation point. In its vicinity, an Eckhaus instability occurs, leading to convectively unstable "blurred" patterns. At the bifurcation point, stochastic effects dominate and induce counterintuitive effects on diversity: Large patterns, emerging for medium values of individuals' mobility, lead to rapid species extinction, while small patterns (low mobility) promote diversity, and high mobilities render spatial structures irrelevant. We provide a quantitative analysis of these phenomena, employing a complex Ginzburg-Landau equation.
Cochlear-bone wave can yield a hearing sensation as well as otoacoustic emission
T. Tchumatchenko,T. Reichenbach
Quantitative Biology , 2014, DOI: 10.1038/ncomms5160
Abstract: A hearing sensation arises when the elastic basilar membrane inside the cochlea vibrates. The basilar membrane is typically set into motion through airborne sound that displaces the middle ear and induces a pressure difference across the membrane. A second, alternative pathway exists, however: stimulation of the cochlear bone vibrates the basilar membrane as well. This pathway, referred to as bone conduction, is increasingly used in the construction of headphones that bypass the ear canal and the middle ear. Furthermore, otoacoustic emissions, sounds generated inside the ear and measured in the ear canal, may not involve the usual wave on the basilar membrane, suggesting that additional cochlear structures are involved in their propagation. Here we describe a novel propagation mode that emerges through deformation of the cochlear bone. Through a mathematical and computational approach we demonstrate that this wave can explain bone conduction as well as numerous properties of otoacoustic emissions.
Discrimination of Low-Frequency Tones Employs Temporal Fine Structure
Tobias Reichenbach, A. J. Hudspeth
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0045579
Abstract: An auditory neuron can preserve the temporal fine structure of a low-frequency tone by phase-locking its response to the stimulus. Apart from sound localization, however, much about the role of this temporal information for signal processing in the brain remains unknown. Through psychoacoustic studies we provide direct evidence that humans employ temporal fine structure to discriminate between frequencies. To this end we construct tones that are based on a single frequency but in which, through the concatenation of wavelets, the phase changes randomly every few cycles. We then test the frequency discrimination of these phase-changing tones, of control tones without phase changes, and of short tones that consist of a single wavelet. For carrier frequencies below a few kilohertz we find that phase changes systematically worsen frequency discrimination. No such effect appears for higher carrier frequencies at which temporal information is not available in the central auditory system.
Preface "Methods and strategies to evaluate landslide hazard and risk"
P. Reichenbach,A. Günther
Natural Hazards and Earth System Sciences (NHESS) & Discussions (NHESSD) , 2010, DOI: 10.5194/nhess-10-2197-2010
Abstract: No abstract available.
Sideband cooling while preserving coherences in the nuclear spin state in group-II-like atoms
Iris Reichenbach,Ivan H. Deutsch
Physics , 2007, DOI: 10.1103/PhysRevLett.99.123001
Abstract: We propose a method for laser cooling group-II-like atoms without changing the quantum state of their nuclear spins, thus preserving coherences that are usually destroyed by optical pumping. As group-II-like atoms have a $^1S_0$ closed-shell ground state, nuclear spin and electronic degrees of freedom are decoupled, allowing for independent manipulation. The hyperfine interaction that couples these degrees of freedom in excited states can be suppressed through the application of external magnetic fields. Our protocol employs resolved-sideband cooling on the forbidden clock transition, $^1S_0 \to {}^3P_0$, with quenching via coupling to the rapidly decaying $^1P_1$ state, deep in the Paschen-Back regime. This makes it possible to laser cool neutral atomic qubits without destroying the quantum information stored in their nuclear spins, as shown in two examples, $^{171}$Yb and $^{87}$Sr.
The physics of hearing: fluid mechanics and the active process of the inner ear
T. Reichenbach,A. J. Hudspeth
Physics , 2014, DOI: 10.1088/0034-4885/77/7/076601
Abstract: Most sounds of interest consist of complex, time-dependent admixtures of tones of diverse frequencies and variable amplitudes. To detect and process these signals, the ear employs a highly nonlinear, adaptive, real-time spectral analyzer: the cochlea. Sound excites vibration of the eardrum and the three miniscule bones of the middle ear, the last of which acts as a piston to initiate oscillatory pressure changes within the liquid-filled chambers of the cochlea. The basilar membrane, an elastic band spiraling along the cochlea between two of these chambers, responds to these pressures by conducting a largely independent traveling wave for each frequency component of the input. Because the basilar membrane is graded in mass and stiffness along its length, however, each traveling wave grows in magnitude and decreases in wavelength until it peaks at a specific, frequency-dependent position: low frequencies propagate to the cochlear apex, whereas high frequencies culminate at the base. The oscillations of the basilar membrane deflect hair bundles, the mechanically sensitive organelles of the ear's sensory receptors, the hair cells. As mechanically sensitive ion channels open and close, each hair cell responds with an electrical signal that is chemically transmitted to an afferent nerve fiber and thence into the brain. In addition to transducing mechanical inputs, hair cells amplify them [...]
Frequency decoding of periodically timed action potentials through distinct activity patterns in a random neural network
Tobias Reichenbach,A. J. Hudspeth
Quantitative Biology , 2012, DOI: 10.1088/1367-2630/14/11/113022
Abstract: Frequency discrimination is a fundamental task of the auditory system. The mammalian inner ear, or cochlea, provides a place code in which different frequencies are detected at different spatial locations. However, a temporal code based on spike timing is also available: action potentials evoked in an auditory-nerve fiber by a low-frequency tone occur at a preferred phase of the stimulus-they exhibit phase locking-and thus provide temporal information about the tone's frequency. In an accompanying psychoacoustic study, and in agreement with previous experiments, we show that humans employ this temporal information for discrimination of low frequencies. How might such temporal information be read out in the brain? Here we demonstrate that recurrent random neural networks in which connections between neurons introduce characteristic time delays, and in which neurons require temporally coinciding inputs for spike initiation, can perform sharp frequency discrimination when stimulated with phase-locked inputs. Although the frequency resolution achieved by such networks is limited by the noise in phase locking, the resolution for realistic values reaches the tiny frequency difference of 0.2% that has been measured in humans.
Dual contribution to amplification in the mammalian inner ear
Tobias Reichenbach,A. J. Hudspeth
Quantitative Biology , 2010, DOI: 10.1103/PhysRevLett.105.118102
Abstract: The inner ear achieves a wide dynamic range of responsiveness by mechanically amplifying weak sounds. The enormous mechanical gain reported for the mammalian cochlea, which exceeds a factor of 4,000, poses a challenge for theory. Here we show how such a large gain can result from an interaction between amplification by low-gain hair bundles and a pressure wave: hair bundles can amplify both their displacement per locally applied pressure and the pressure wave itself. A recently proposed ratchet mechanism, in which hair-bundle forces do not feed back on the pressure wave, delineates the two effects. Our analytical calculations with a WKB approximation agree with numerical solutions.
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