Relationship between ocean velocity and motionally induced electrical signals: 1. in the presence of horizontal velocity gradients

Motionally induced electric fields and electric currents in the ocean depend to first order solely on the vertical dimension. We investigate the significance of two-dimensional (2-D) perturbations that arise in the presence of horizontal velocity gradients. The full electric response is calculated for two schematic geometries that contain horizontal velocity gradients, have a two-layer ocean with a layer of sediment beneath, and are described by four nondimensional parameters. When considered over the realistic ranges of oceanic aspect ratio (the ratio of water depth to the width of velocity), sediment thickness, and sediment conductivity, velocity errors arising from 2-D perturbations are found to be less than a few percent of the dominant one-dimensional (1-D) signal. All errors depend on the aspect ratio to the power of 1.9 (1) for signals induced by the vertical (horizontal) component of the Earth's magnetic field. Depth-uniform velocity errors are proportional to the 1-D sediment conductance ratio, whereas depth-varying velocity errors are independent of sediment thickness or conductivity. Errors are weakly (proportionally) dependent on the jet depth for signals induced by the vertical (horizontal) component of the magnetic field. Two-dimensional perturbations decay away from the forcing region with a half width of 0.2-1 times the 1-D effective water depth. This study extends the first-order theory to the maximum expected aspect ratios for oceanic flow and finds small perturbations with simple dependencies on the nondimensional parameters

Relationship between ocean velocity and motionally induced electrical signals: 2. in the presence of sloping topography

Motionally induced electric fields and electric currents in the ocean depend to first order solely on the vertical dimension. We investigate the significance of two-dimensional (2-D) perturbations that arise in the presence of sloping topography. The full electric response is calculated for a schematic geometry that contains a topographic slope, has a two-layer ocean with a layer of sediment beneath, and is described by five nondimensional parameters. When considered over the realistic ranges of topographic aspect ratio (the ratio of mean water depth to topographic width), topographic relief, sediment thickness, and sediment conductivity, velocity errors arising from 2-D perturbations are found to be less than a few percent of the dominant one-dimensional (1-D) signal. All errors depend on the topographic aspect ratio to the power of 1.9 and have linear dependence on topographic relief and the depth of the surface jet. Depth-uniform velocity errors are roughly proportional to the 1-D sediment conductance ratio, whereas depth-varying velocity errors are independent of sediment thickness or conductivity. Two-dimensional perturbations decay with a half width of 0.2–1 times the 1-D effective water depth. The magnitude of estimated errors is consistent with those found at a measurement location with strong 2-D perturbations. This study extends the first-order theory to the maximum expected aspect ratios for topography and finds small perturbations with simple dependencies. Overall, the 1-D approximation is found to be adequate for interpreting observations at all but the most extreme locations

A vertical-mode decomposition to investigate low-frequency internal motion across the Atlantic at 26° N

Hydrographic data from full-depth moorings maintained by the Rapid/\-MOCHA project and spanning the Atlantic at 26° N are decomposed into vertical modes in order to give a dynamical framework for interpreting the observed fluctuations. Vertical modes at each mooring are fit to pressure perturbations using a Gauss-Markov inversion. Away from boundaries, the vertical structure is almost entirely described by the first baroclinic mode, as confirmed by high correlation between the original signal and reconstructions using only the first baroclinic mode. These first baroclinic motions are also highly coherent with altimetric sea surface height (SSH). Within a Rossby radius (45 km) of the western and eastern boundaries, however, the decomposition contains significant variance at higher modes, and there is a corresponding decrease in the agreement between SSH and either the original signal or the first baroclinic mode reconstruction. Compared to the full transport signal, transport fluctuations described by the first baroclinic mode represent <25 km of the variance within 10 km of the western boundary, in contrast to 60 km at other locations. This decrease occurs within a Rossby radius of the western boundary. At the eastern boundary, a linear combination of many baroclinic modes is required to explain the observed vertical density profile of the seasonal cycle, a result that is consistent with an oceanic response to wind-forcing being trapped to the eastern boundary

Kálium ion-csatornák szerepének vizsgálata szívizomsejtekben a génkifejeződés RNS interferencia révén történő blokkolásával = Investigation of the role of potassium ion channels of heart muscle cells by means of RNA interference-mediated blocking of gene expression

Kutatási témánk a szívizom kálium ioncsatornáinak vizsgálata RNS interferencia technikával. Az RNS interferenciát kiváltó expressziós kazettát Aujeszky-féle vírus (AyV) vektorral juttattuk be a szívizomsejtekbe. A konkrét feladat megoldásához több olyan általános problémát is meg kellett oldanunk, amelyhez modellként egy másik posztmitotikus sejttípust, az idegsejteket is felhasználtuk. A munka első fázisában fluoreszcens markereket kifejező AyV törzseket állítottunk elő. E kísérletek célja a vírus génbeviteli hatékonyságának tesztelése volt. Különböző színű markereket vittünk be posztmitotikus sejtekbe (szívizom, idegsejtek). Tenyésztett felnőtt kutya szívizomsejtekben a génbeviteli hatékonyság, magas vírus titer alkalmazásával, közel 100%-os volt. Megvizsgáltuk azt is, hogy a PRV által bevitt gének működőképesek-e a célsejtekben, ill. hogy a vírus hatással van-e ezekre a sejtekre. Modellként egy fluoreszcens kalcium szenzort, a troponeont használtuk. A troponeon mind szívizomsejtekben, mind neuronokban kiválóan működött. A virulencia csökkentése végett különféle PRV mutánsokat állítottunk elő. A korai fehérje 0, a ribonukleotid reduktáz gének kiütése és az ún. antiszensz promóter inaktiválása olyan vírust eredményezett, amely epitél sejteken (PK-15 sejtvonal, ezen szaporítjuk a vírust) megfelelően szaporodott, szívizomsejtekben azonban avirulensnek bizonyult. Továbbá, kutya Kv4.3 gént csendesítő RNS interferenciát közvetítő vírusokat állítottunk elő. | Our research project is the analysis of cardiac potassium ion channels using RNA interference technique. We used pseudorabies virus (PRV) vectors for the delivery of expression cassettes evoking RNA interference. In the first phase of our work we constructed various fluorescence proteins expressing recombinant viruses. The aim of this work was to test the efficiency of gene delivery by the virus. We delivered fluorescence markers with various colors to cardiomyocytes and neurons. The efficiency of PRV-based gene delivery to canine cardiomyocytes was close to 100% in high titer virus infection. The fluorescent markers were delivered to neurons in vivo using mouse and rat models. The next step was the examination whether the delivered gene retains its functionality in a virus-based system. We have used troponeon, a genetically encoded fluorescence activity marker, as model to test this problem. According to our examinations, troponeon, delivered to both cardiomyocytes and neurons, performed very well in both cell types. We have constructed various mutant PRV strains by the deletion of early protein 0 and ribonucleotide reductase genes, as well as the deleted the putative antisense promoter region of the virus. PRVs containing these triple mutations proved to be ideal gene delivery vectors to cardiomyocytes. Furthermore, we have generated viruses expressing the hairpin RNAs for knocking down Kv4.3 gene expression of the dog cardiomyocytes

Lipid-fehérje kölcsönhatás és dinamika vizsgálata modell és biológiai membránokban. Egy új, nanotechnológiás, membránfehérje vizsgáló rendszer kifejlesztése. = Lipid-protein interactions, and dynamics in model and biological membranes. The development of a new experimental nano-technologic device to study structure and functioning of membrane-proteins.

Összehasonlítva a biológiai membránokban a lipid-, illetve a fehérje-dinamika, illetve a fehérjék másodlagos szerkezetváltozásainak hőmérsékletfüggését, megállapítottuk, hogy alacsony hőmérsékleti stressz körülményei között elsősorban a lipidek, magas hőmérsékleti stressz esetén pedig a fehérjék dinamika/szerkezet változásai a meghatározóak a biológiai membrán viselkedésében. (PMC Biophysics (2009) 2:1, Biochemistry (2009) 48, 10120-10128) Polielektrolitokból készített, tetszőlegesen töltött felszíneken felépített egy-molekula vastagságú kazein rétegek adszorpciójának nyomon követésével meghatároztuk a Ca-foszfát szállításáért felelős kazein micellák kialakulásának mechanizmusát. Megmutattuk, hogy a kazein micellák belsejében levő ?-kazein molekulák foszfoszeril csoportjaihoz kapcsolódnak a Ca-foszfát nanoklaszterek, amikhez a további ?-kazeinek pozitív csoportjaikkal kötődnek. Az ?-kazeinek hidrofób csoportjainak kölcsönhatása révén, kis, kb. 20 nm-es aggregátumok alakulnak ki, amelyeket a Ca-foszfát nanoklaszterek kapcsolnak össze. A micellák felszínére ?-kazein molekulák tapadnak, amik “lágyabb“ szerkezetük révén befedik azokat a pontokat az ?-kazeinek felszínén, amik a további akár ?-kazein, akár Ca-foszfát kötődéshez kellenek, és így a micella képződése befejeződik, felszínét ?-kazein molekulák borítják, amik nem érzékenyek a Ca-ionokra, mint az ?-kazein, így a micellák nem csapódnak ki. ( JBC (2010) 285, 38811-38817, Eur Biophys J(2012) 41:959-968) | Using Attenuated Total Reflection Fourier Transform Infrared (ATR-FTIR) spectroscopy, we have compared lipid and protein dynamics/structural changes as a function of the temperature in biological membranes. It has been shown that among low-temperature stress conditions the changes in the dynamics of the lipids, among high-temperature stress conditions the changes of the protein dynamics and secondary structure are dominant in the behaviour of the membranes. (PMC Biophysics (2009) 2:1, Biochemistry (2009) 48, 10120-10128) By preparing polyelectrolyte films having charged surfaces, and building onto them layer-by-layer aggregated casein-Ca-phosphate complexes, we determined the mechanism of the construction of the casein micelles, the essential components of Ca-phosphate transport in mammals. We have shown that the phosphoseryl residues on the ?-casein molecules are essential for binding the Ca-phosphate. The bound Ca-phosphate nanoclusters bind the next layer of the ?-caseins, as so on. Hydrophobic parts of the amphiphilic molecules organize ?-caseins into about 20 nm diameter aggregates, interconnected by Ca-phosphate nanoclusters. Termination of the micelle formation is achieved via the adsorption of ?-casein onto the micelle surface. Due to its “soft“ secondary structure, ?-casein can cover those parts of the ?-casein molecules, which are essential for Ca-phosphate binding and further aggregation of ?-caseins. (JBC (2010) 285, 38811-38817, Eur Biophys J(2012) 41:959-968

The same but different : equally megadiverse but taxonomically variant spider communities along an elevational gradient

Spatial variation in biodiversity is one of the key pieces of information for the delimitation and prioritisation of protected areas. This information is especially important when the protected area includes different climatic and habitat conditions and communities, such as those along elevational gradients. Here we test whether the megadiverse communities of spiders along an elevational gradient change according to two diversity models - a monotonic decrease or a hump-shaped pattern in species richness. We also measure compositional variation along and within elevations, and test the role of the preference of microhabitat (vegetation strata) and the functional (guild) structure of species in the changes. We sampled multiple spider communities using standardised and optimised sampling in three forest types, each at a different elevation along a climatic gradient. The elevational transects were at increasing horizontal distances (between 0.1 and 175 km) in the Udzungwa Mountains, Eastern Arc Mountains, Tanzania. The number of species was similar between plots and forest types, and therefore the pattern did not match either diversity model. However, species composition changed significantly with a gradual change along elevations. Although the number of species per microhabitat and guild also remained similar across elevations, the number of individuals varied, e.g. at higher elevations low canopy vegetation was inhabited by more spiders, and the spiders belonging to guilds that typically use this microhabitat were more abundant. Our findings reflex the complex effects of habitat-microhabitat interactions on spider communities at the individual, species and guild levels. If we aim to understand and conserve some of the most diverse communities in the world, researchers and managers may need to place more attention to small scale and microhabitat characteristics upon which communities depend.Peer reviewe

Continuous estimate of Atlantic oceanic freshwater flux at 26.5°N

The first continuous estimates of freshwater flux across 26.5°N are calculated using observations from the RAPID–MOCHA–Western Boundary Time Series (WBTS) and Argo floats every 10 days between April 2004 and October 2012. The mean plus or minus the standard deviation of the freshwater flux (FW) is −1.17 ± 0.20 Sv (1 Sv ≡ 106 m3 s−1; negative flux is southward), implying a freshwater divergence of −0.37 ± 0.20 Sv between the Bering Strait and 26.5°N. This is in the sense of an input of 0.37 Sv of freshwater into the ocean, consistent with a region where precipitation dominates over evaporation. The sign and the variability of the freshwater divergence are dominated by the overturning component (−0.78 ± 0.21 Sv). The horizontal component of the freshwater divergence is smaller, associated with little variability and positive (0.35 ± 0.04 Sv). A linear relationship, describing 91% of the variance, exists between the strength of the meridional overturning circulation (MOC) and the freshwater flux (−0.37 − 0.047 Sv of FW per Sverdrups of MOC). The time series of the residual to this relationship shows a small (0.02 Sv in 8.5 yr) but detectable decrease in the freshwater flux (i.e., an increase in the southward freshwater flux) for a given MOC strength. Historical analyses of observations at 24.5°N are consistent with a more negative freshwater divergence from −0.03 to −0.37 Sv since 1974. This change is associated with an increased southward freshwater flux at this latitude due to an increase in the Florida Straits salinity (and therefore the northward salinity flux)

Altered Potassium Ion Homeostasis in Hearing Loss

Connexins, Kv-type ion channels, and pannexins have a dominant role in maintaining the potassium ion homeostasis in the cochlea. The cellular background currents are sustained by Kir2.1 ion channels; however, their involvement in the hearing system is less clear. In this study, the mutations of gap junction proteins beta 2 (GJB2), beta 3 (GJB3) and beta 6 (GJB6) were screened in the white Caucasian population in Hungary using gene mapping and immunofluorescence methods from translated proteins of these genes—connexins on blood cells. Expression of connexins and Kir2.1 ion channels was investigated in the blood cells of deaf patients prior to cochlear implantation, and the results show significantly decreased amounts of connexin26 and connexin43. In addition, the coexpression of Kir2.1 ion channels with synapse-associated 97 proteins was partially impaired. Our investigation revealed a reduced level of Kir2.1 channels in deaf patients indicating a crucial role for the functional Shaker superfamily of K+ channels in the non-diseased hearing system