Coassembly of K(V)LQT1 and minK (IsK) proteins to form cardiac I(Ks) potassium channel

The slowly activating delayed-rectifier K+ current, I(Ks), modulates the repolarization of cardiac action potentials. The molecular structure of the I(Ks) channel is not known, but physiological data indicate that one component of the I(Ks), channel is minK, a 130-amino-acid protein with a single putative transmembrane domain. The size and structure of this protein is such that it is unlikely that minK alone forms functional channels. We have previously used positional cloning techniques to define a new putative K+-channel gene, KVLQT1. Mutations in this gene cause long-QT syndrome, an inherited disorder that increases the risk of sudden death from cardiac arrhythmias. Here we show that KVLQT1 encodes a K+ channel with biophysical properties unlike other known cardiac currents. We considered that K(V)LQT1 might coassemble with another subunit to form functional channels in cardiac myocytes. Coexpression of K(V)LQT1 with minK induced a current that was almost identical to cardiac I(Ks). Therefore, K(V)LQT1 is the subunit that coassembles with minK to form I(Ks) channels and I(Ks) dysfunction is a cause of cardiac arrhythmia.     

Effects of Vegetation Cover on the Radar Sensitivity to Soil Moisture

Measurements of the backscattering coefficient ?°, made for bare and vegetation-covered fields, are used in conjunction with a simple backscattering model to evaluate the effects of vegetation cover on the estimation accuracy of soil moisture when derived from radar observations. The results indicate that for soil moisture values below 50 percent of field capacity, the backscatter contribution of the vegetation cover limits the radar's ability to predict soil moisture with an acceptable degree of accuracy. However, for moisture values in the range between 50 and 150 percent of field capacity, the measured ?° is dominated by the soil contribution and the effects of vegetation cover become secondary in importance. It is estimated that in this upper soil moisture range, which is the primary range of interest in hydrology and agriculture, a radar soil moisture prediction algorithm would predict soil moisture with an error of less than ±15 percent of field capacity in 90 percent of the cases.     

The effects of substitution on the eletrochemical reduction of dihydroxynaphtacenequinone in N,N-dimethylformamide

The electrochemical reduction of 6,11-dihydroxy-5,12-naphthacenequinone (DHNQ) in N,N- dimethylformamide was investigated. Under polarographic conditions, DHNQ behaves like a simple aromatic quinone with reduction occuring in two successive one-electron steps followed by protonation in the aprotic system and a single two-electron irreversible in the protic medium. The substituent inductive effects in several DHNQ derivatives were noted. The electron withdrawing groups, chloro and phenylsulfonyl, enhance the oxidation potentials, and the eletron-releasing groups, methyl and methoxy, make the reduction more difficult. The strength of the substituents follows the order: C₆H₅SO₂ ? Cl ? CH₃ ? CH₃O. A linear Hammett relationship exists in this series when the averaged value of σ_meta and σ_para are used as substitution constants.     

The fast removal of low concentration of cadmium(II) from aqueous media by chelating polymers with salicylaldehyde units

Poly[4-(4-vinylbenzyloxy)-2-hydrobenzaldehyde], PVBH, a salicylaldehyde chelating functional group-based polymer has been found to be capable of the removal of low concentration of cadmium metal ion in ppb level from aqueous media. The adsorption fits best with the Langmuir model, indicating the monolayer coverage of the metal ion on the surface of chelating polymer. The R_L values have indicated the favorable adsorption in the range of all the ppb concentrations studied. The kinetic study has revealed a very fast adsorption process with the rate following the pseudo-second-order.     

Modification of the Ehrlich ascites tumor cell nuclear lipids

The fatty acid composition of Ehrilich ascites tumor cell nuclei was differend when the tumor-bearing mice were fed diets rich in either coconut or sunflower oil. When coconut oil was fed, the monoenoic fatty acid content of many of the nuclear lipids was increased and their polyenoic fatty acid content was reduced as compared with the sunflower oil diet. By contrast, only small changes were produced in the saturated fatty acid contents of the nuclear lipids. The nuclear membrane choline phospholipid, ethanolamine phospholipid and combined serine phospholipid plus inositol phospholipid fractions exhibited statistically significant changes in fatty acid composition, but the sphingomyelins were not altered appreciably by dietary lipid modification. The fatty acid composition of the small quantity of phospholipids associated with the chromatin was much more resistant to diet-induced mosification. Except for sphingomyelin, the fatty acid composition of the chromatin phospholipids was different from that of the corresponding nuclear membrane phospholipids, containing much larger amounts of fatty acids having less than 16 carbon atoms. The fatty acid compositons of the nuclear triaclglycerols and cholesterol esters, which were associated almost entirely with the chromatin, were modified by the dietary lipid modifications. There were no changes in the DNA, RNA or lipid content of these nuclei. Therefore, this experimental system can be used to prepare mamalian nuclei that differ appreciably only in their fatty acyl composition.     

Processes affecting oxygen isotope ratios of atmospheric and ecosystem sulfate in two contrasting forest catchments in Central Europe

Sulfate aerosols are harmful as respirable particles. They also play a role as cloud condensation nuclei and have radiative effects on global climate. A combination of delta18O-SO4 data with catchment sulfur mass balances was used to constrain processes affecting S cycling in the atmosphere and spruce forests of the Czech Republic. Extremely high S fluxes via spruce throughfall and runoff were measured at Jezeri (49 and 80 kg S ha(-1) yr(-1), respectively). The second catchment, Na Lizu, was 10 times less polluted. In both catchments, delta18O-SO4 decreased in the following order: open-area precipitation > throughfall > runoff. The delta18O-SO4 values of throughfall exhibited a seasonal pattern at both sites, with maxima in summer and minima in winter. This seasonal pattern paralleled delta18O-H2O values, which were offset by -18 per thousand. Sulfate in throughfall was predominantly formed by heterogeneous (aqueous) oxidation of SO2. Wet-deposited sulfate in an open area did not show systematic delta18O-SO4 trends, suggesting formation by homogeneous (gaseous) oxidation and/or transport from large distances. The percentage of incoming S that is organically cycled in soil was similar under the high and the low pollution. High-temperature 18O-rich sulfate was not detected, which contrasts with North American industrial sites.     

Chorda tympani nerve transection, but not amiloride, increases the KCl taste detection threshold in rats.

Water-restricted rats were trained to press one lever after KCl presentation and the other lever after distilled water. Water reinforcement was given after each correct response, and a time-out followed each incorrect response. Rats were trained and tested on KCl stimuli of varying concentrations. Threshold was defined as the KCl concentration corresponding to ? the maximum asymptote of performance for each rat. The geometric mean KCl detection threshold for all rats was 0.033 M KCl. Rats that had the chorda tympani nerve (ChT) bilaterally transected showed an average increase in KCl threshold of approximately 0.60 log?? units, whereas sham-operated rats showed no change. Control rats retested with 100 μM amiloride added to all KCl concentrations and water displayed no change in threshold. These results suggest that although the ChT contributes significantly to the rat's sensitivity to KCl, amiloride-sensitive taste transduction pathways do not. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Behavioral mechanisms for active maternal potentiation of isolation calling in rat pups.

The ultrasonic vocalization (USV) response of the isolated infant rat is a promising model for studying the neurobiology of an early anxiety state, and potentiation of the USV response after brief maternal encounters is a newly discovered behavioral regulator of this state. Using experimental variations in the contexts and patterns of maternal behavior during pup encounters and manual simulations of maternal behavior, we have identified several specific mother–pup interactions that cause potentiation. When one of these, pup carrying, was manually simulated, potentiation followed only if a characteristic postural transport response had been fully expressed by the pup. These behavioral mechanisms and other data suggest hypotheses for the development and adaptive role of maternal potentiation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)