Similarities and differences in interaction of K+ and Na+ with condensed ordered DNA. A molecular dynamics computer simulation study

Four 20 ns molecular dynamics simulations have been performed with two counterions, K⁺ or Na⁺, at two water contents, 15 or 20 H₂O per nucleotide. A hexagonal simulation cell comprised of three identical DNA decamers [d(5′-ATGCAGTCAG) × d(5′-TGACTGCATC)] with periodic boundary condition along the DNA helix was used. The simulation setup mimics the DNA state in oriented DNA fibers or in crystals of DNA oligomers. Variation of counterion nature and water content do not alter averaged DNA structure. K⁺ and Na⁺ binding to DNA are different. K⁺ binds to the electronegative sites of DNA bases in the major and the minor grooves, while Na⁺ interacts preferentially with the phosphate groups. Increase of water causes a shift of both K⁺ and Na⁺ from the first hydration shell of O1P/O2P and of the DNA bases in the minor groove with lesser influence for the cation binding to the bases in the major groove. Mobility of both water and cations in the K–DNA systems is faster than in the Na–DNA systems: Na⁺ organizes and immobilizes water structure around itself and near DNA while for K⁺ water is less organized and more dynamic.     

Photoluminescence and thermoluminescence properties of pure and rare-earth-doped ZrO2 prepared by Pechini-type sol–gel

In this article, photoluminescence (PL) and thermoluminescence (TL) properties of ZrO₂, ZrO₂:Dy³⁺, ZrO₂:Dy³⁺–Gd³⁺, ZrO₂:Dy³⁺–Yb³⁺, ZrO₂:Dy³⁺–Er³⁺, and ZrO₂:Dy³⁺–Sm³⁺ phosphors synthesized by the Pechini method were investigated. The crystal structure, thermal properties, morphology, PL and TL properties were investigated using X-ray powder diffraction (XRD), differential thermal analysis/thermogravimetric analysis (DTA/TGA), scanning electron microscopy (SEM), PL and TL, respectively. The room temperature emission bands corresponding to ⁴F_9/2 → ⁶H_J (J = 9/2, 11/2, 13/2 and 15/2) transitions of Dy³⁺ ions were measured. The phosphors were analysed using T_m–T_STOP, variable dose, and computerized glow curve fitting methods. Reusability, dose–response, and fading characteristics were investigated. The phosphors have a natural TL emission that vanished by heating treatment. Moreover, new peaks with similar properties to the natural emissions were observed after high-dose irradiation and long-term fading experiments. The glow curves of the phosphors have 13 individual peaks and many low- and high-temperature satellite peaks. The origin of the peaks is ZrO₂ host material and doping with rare-earth ions (Gd³⁺, Dy³⁺, Yb³⁺, Er³⁺ and Sm³⁺) does not lead to a new glow peak. The dopants cause drastic changes in individual peak intensities of ZrO₂.The initial fading rates of all the phosphors are relatively fast, but they slow down as time goes on.     

A Discriminant Analysis of Trace Elements in Scalp Hair of Healthy Controls and Stage-IIIB Non-small Cell Lung Cancer (NSCLC) Patients

Our work aimed at extending the search for the trace elements (TE) abnormalities in patients with lung cancer and in healthy controls who smoke, and also for evidence of a possible association between lung cancer and TE. The analysis of the hair from patients with Stage-IIIB non-small cell lung cancer (group 1) and healthy controls (group 2) were analyzed using the inductively coupled plasma mass spectrometry technique in order to obtain information on the correlation between the lung cancer patients and healthy controls. Sixty-seven one-hair samples in group 1 were individually collected before chemoradiotherapy. For comparison, 74 hair samples were collected from group 2. In group 1, the trace elements present at the highest levels were measured to be Ca, Zn, Sn, Na and Mg, respectively, and they were quantified as 68.2, 53.2, 33.9, 23.3, and 28.9?μg.kg(-1), respectively. In group 2, the trace elements present at the highest levels were Zn, Mg, Ca, Fe, and Se, respectively, and they were quantified as 109.7, 31.9, 30.8, 25.0, and 20.1?μg.kg(-1). In group 1, the highest levels of Ca, Sn, and Na were 2.03, 1.06, and 1.01 times higher, respectively, compared with group 2. In group 2, Zn, Mg, Fe, and Se were 2, 1.01, 2.7, and 1.6 times higher, respectively, compared with group 1. When the levels of trace elements were compared between groups 1 and 2 using Student's t test, the levels of Ag, Au, Be, Bi, Ca, Cd, Ce, Co, Cr, Cu, Fe, Ga, Hg, K, Ni, Rb, Rh, Sb, Sc, Ti, V, and Zn were found to be statistically different (p?相似文献   

Effect of lysophosphatidylcholine on the NADH-ferricyanide reductase activity associated with the plasma membranes of corn roots

Plasma membranes from corn roots (Zea mays L.) were isolated by aqueous two-phase partitioning. A fraction enriched in a vanadate-sensitive ATPase showed characteristics of a plasma membrane ATPase. The sidedness of these vesicles was 89% right-side-out, as evaluated by the ATPase latency. A NADH-ferricyanide reductase was associated with these plasma membrane vesicles. The rate of ferricyanide reduction was 1.3 μmol · min⁻¹·mg⁻¹ protein and was strongly enhanced by the addition of lysophosphatidylcholine (LPC). The effect of this detergent on membrane solubilization and reductase activity was particularly studied. This type of detergent treatment revealed two pH optima (7.0 and 5.0) for the reductase activity, which exhibited biphasic kinetics in the absence or presence of the detergent. These data suggest that two or more reductases could be involved. In addition, membrane vesicle solubilization and determination of ATPase and reductase latency were simultanously studied. From these experiments, it is postulated that the reductase, which exhibits an optimum pH at 7.0 and is slightly stimulated by LPC, could be located on the external side of the plasmalemma. In contrast, the reductase at pH 5.0 strongly stimulated by the detergent treatment, is probably located on the internal side of the membrane, such as the catalytic site of ATPase. Finally, a possible direct action of LPC on the enzymes, is discussed.     

Significant linkage disequilibrium between the Huntington disease gene and the loci D4S10 and D4S95 in the Dutch population.

Significant linkage disequilibrium has been found between the Huntington disease (HD) gene and DNA markers located around D4S95 and D4S98. The linkage-disequilibrium studies favor the proximal location of the HD gene, in contrast to the conflicting results of recombination analyses. We have analyzed 45 Dutch HD families with 19 DNA markers and have calculated the strength of linkage disequilibrium. Highly significant linkage disequilibrium has been detected with D4S95, consistent with the studies in other populations. In contrast with most other studies, however, the area of linkage disequilibrium extends from D4S10 proximally to D4S95, covering 1,100 kb. These results confirm that the HD gene most likely maps near D4S95.     

Probing the HIV-1 Genomic RNA Trafficking Pathway and Dimerization by Genetic Recombination and Single Virion Analyses

Once transcribed, the nascent full-length RNA of HIV-1 must travel to the appropriate host cell sites to be translated or to find a partner RNA for copackaging to form newly generated viruses. In this report, we sought to delineate the location where HIV-1 RNA initiates dimerization and the influence of the RNA transport pathway used by the virus on downstream events essential to viral replication. Using a cell-fusion-dependent recombination assay, we demonstrate that the two RNAs destined for copackaging into the same virion select each other mostly within the cytoplasm. Moreover, by manipulating the RNA export element in the viral genome, we show that the export pathway taken is important for the ability of RNA molecules derived from two viruses to interact and be copackaged. These results further illustrate that at the point of dimerization the two main cellular export pathways are partially distinct. Lastly, by providing Gag in trans, we have demonstrated that Gag is able to package RNA from either export pathway, irrespective of the transport pathway used by the gag mRNA. These findings provide unique insights into the process of RNA export in general, and more specifically, of HIV-1 genomic RNA trafficking.     

The brain organization of butterflyfishes

Synopsis The encephalization indices of angelfishes (Pomacanthidae) and butterflyfishes (Chaetodontidae) are typical of advanced perciform fishes: both families lie in the upper part of the polygon of teleost indices. The chaetodontids seem to be a little more encephalized than pomacanthids. The general morphology of the brains in both families is very similar: small olfactory bulbs, large optic tectum and a cerebellum which covers the brain structures in front of it like a cap. This morphology is shared by another family of the coral reef biotope, the Acanthuridae. The histological architecture is also typical of advanced teleosts, with a cortex-like pallium, a laminated nucleus geniculatus (= pretectalis superficialis), a complex valvula cerebelli and a corpus glomerulosum with a clear neuropile centre. The quantitative analysis of the main subdivisions of the brain, either from relative volumes or from indices, shows small olfactory bulbs (microsmy) but important telencephalic and diencephalic centres, large tectal centres (vision) and large cerebellum (precise locomotion). Many of these peculiarities are shared by other fishes inhabiting coral reefs. The differences between the two families seem to be primarily correlated with food habits: the angelfishes, which are sponge-feeders and may have an overweight due to the ballast of the sponge-skeleton in their digestive tract, and which do not need either such good vision or such precise locomotion to pick up their prey, could be a little less encephalized than the butterflyfishes.     

Maternal Filaggrin Mutations Increase the Risk of Atopic Dermatitis in Children: An Effect Independent of Mutation Inheritance

Epidemiological studies suggest that allergy risk is preferentially transmitted through mothers. This can be due to genomic imprinting, where the phenotype effect of an allele depends on its parental origin, or due to maternal effects reflecting the maternal genome''s influence on the child during prenatal development. Loss-of-function mutations in the filaggrin gene (FLG) cause skin barrier deficiency and strongly predispose to atopic dermatitis (AD). We investigated the 4 most prevalent European FLG mutations (c.2282del4, p.R501X, p.R2447X, and p.S3247X) in two samples including 759 and 450 AD families. We used the multinomial and maximum-likelihood approach implemented in the PREMIM/EMIM tool to model parent-of-origin effects. Beyond the known role of FLG inheritance in AD (R1_{meta-analysis} = 2.4, P = 1.0 x 10⁻³⁶), we observed a strong maternal FLG genotype effect that was consistent in both independent family sets and for all 4 mutations analysed. Overall, children of FLG-carrier mothers had a 1.5-fold increased AD risk (S1 = 1.50, P_{meta-analysis} = 8.4 x 10⁻⁸). Our data point to two independent and additive effects of FLG mutations: i) carrying a mutation and ii) having a mutation carrier mother. The maternal genotype effect was independent of mutation inheritance and can be seen as a non-genetic transmission of a genetic effect. The FLG maternal effect was observed only when mothers had allergic sensitization (elevated allergen-specific IgE antibody plasma levels), suggesting that FLG mutation-induced systemic immune responses in the mother may influence AD risk in the child. Notably, the maternal effect reported here was stronger than most common genetic risk factors for AD recently identified through genome-wide association studies (GWAS). Our study highlights the power of family-based studies in the identification of new etiological mechanisms and reveals, for the first time, a direct influence of the maternal genotype on the offspring’s susceptibility to a common human disease.