Connexin36 knockout mice display increased sensitivity to pentylenetetrazol-induced seizure-like behaviors

Large-scale synchronous firing of neurons during seizures is modulated by electrotonic coupling between neurons via gap junctions. To explore roles for connexin36 (Cx36) gap junctions in seizures, we examined the seizure threshold of connexin36 knockout (Cx36KO) mice using a pentylenetetrazol (PTZ) model

Antiapoptotic Actions of Methyl Gallate on Neonatal Rat Cardiac Myocytes Exposed to H 2

Reactive oxygen species trigger cardiomyocyte cell death via increased oxidative stress and have been implicated in the pathogenesis of cardiovascular diseases. The prevention of cardiomyocyte apoptosis is a putative therapeutic target in cardioprotection. Polyphenol intake has been associated with reduced incidences of cardiovascular disease and better overall health. Polyphenols like epigallocatechin gallate (EGCG) can reduce apoptosis of cardiomyocytes, resulting in better health outcomes in animal models of cardiac disorders. Here, we analyzed whether the antioxidant N-acetyl cysteine (NAC) or polyphenols EGCG, gallic acid (GA) or methyl gallate (MG) can protect cardiomyocytes from cobalt or H2O2-induced stress. We demonstrate that MG can uphold viability of neonatal rat cardiomyocytes exposed to H2O2 by diminishing intracellular ROS, maintaining mitochondrial membrane potential, augmenting endogenous glutathione, and reducing apoptosis as evidenced by impaired Annexin V/PI staining, prevention of DNA fragmentation, and cleaved caspase-9 accumulation. These findings suggest a therapeutic value for MG in cardioprotection

Does pyrite act as an important host for molybdenum in modern and ancient euxinic sediments?

Molybdenum (Mo) is a popular paleoproxy for tracking the spatiotemporal pattern of euxinic (anoxic and sulfidic) conditions in the ancient ocean, yet surprisingly little is known about the processes leading to its fixation under sulfidic conditions. Pyrite has been proposed to be the main host phase for Mo sequestration. To clarify the role played by pyrite, and thus to refine the utility of this paleoproxy, modern and ancient samples from six different study sites were analyzed, all representing euxinic conditions, using laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). Although pyrite often shows substantial enrichments relative to average crust and even matrix samples of similar size, our results show that most of the Mo in euxinic muds and shales is found in the non-pyrite matrix (80–100%) and not in the pyrite grains (0–20%)—simply because the volume of matrix dominates the bulk sediments/rocks. A relationship between the percent of Mo hosted by pyrite and the sulfur isotope composition of that pyrite is observed and can be linked to post-depositional alteration. Specifically, the oldest, typically most altered samples, show the highest δ^(34)S values because of limited sulfate availability at the time of their formation in the early ocean. In these old samples, the relatively small amount of Mo sequestered initially within pyrite is more likely to have been released to the matrix during the strong recrystallization overprints that these rocks have disproportionately suffered. Despite the universal importance of appreciable H_2S availability during Mo uptake, we conclude that pyrite should be viewed as a nontrivial sink for Mo but clearly not the primary host in most euxinic shales and rather suggest that other burial pathways should be emphasized in future studies of the mechanisms of Mo sequestration in such settings

Localized retroprocessing as a model of intron loss in the plant mitochondrial genome

Loss of introns in plant mitochondrial genes is commonly explained by retroprocessing. Under this model, an mRNA is reverse transcribed and integrated back into the genome, simultaneously affecting the contents of introns and edited sites. To evaluate the extent to which retroprocessing explains intron loss, we analyzed patterns of intron content and predicted RNA editing for whole mitochondrial genomes of 30 species in the monocot order Alismatales. In this group, we found an unusually high degree of variation in the intron content, even expanding the hitherto known variation among angiosperms. Some species have lost some two-third of the cis-spliced introns. We found a strong correlation between intron content and editing frequency, and detected 27 events in which intron loss is consistent with the presence of nucleotides in an edited state, supporting retroprocessing. However, we also detected seven cases of intron loss not readily being explained by retroprocession. Our analyses are also not consistent with the entire length of a fully processed cDNA copy being integrated into the genome, but instead indicate that retroprocessing usually occurs for only part of the gene. In some cases, several rounds of retroprocessing may explain intron loss in genes completely devoid of introns. A number of taxa retroprocessing seem to be very common and a possibly ongoing process. It affects the entire mitochondrial genome

A new spin-anisotropic harmonic honeycomb iridate

The physics of Mott insulators underlies diverse phenomena ranging from high temperature superconductivity to exotic magnetism. Although both the electron spin and the structure of the local orbitals play a key role in this physics, in most systems these are connected only indirectly --- via the Pauli exclusion principle and the Coulomb interaction. Iridium-based oxides (iridates) open a further dimension to this problem by introducing strong spin-orbit interactions, such that the Mott physics has a strong orbital character. In the layered honeycomb iridates this is thought to generate highly spin-anisotropic interactions, coupling the spin orientation to a given spatial direction of exchange and leading to strongly frustrated magnetism. The potential for new physics emerging from such interactions has driven much scientific excitement, most recently in the search for a new quantum spin liquid, first discussed by Kitaev \cite{kitaev_anyons_2006}. Here we report a new iridate structure that has the same local connectivity as the layered honeycomb, but in a three-dimensional framework. The temperature dependence of the magnetic susceptibility exhibits a striking reordering of the magnetic anisotropy, giving evidence for highly spin-anisotropic exchange interactions. Furthermore, the basic structural units of this material suggest the possibility of a new family of structures, the `harmonic honeycomb' iridates. This compound thus provides a unique and exciting glimpse into the physics of a new class of strongly spin-orbit coupled Mott insulators.Comment: 12 pages including bibliography, 5 figure

Mitochondrial genome evolution in Alismatales: Size reduction and extensive loss of ribosomal protein genes

<div><p>The order Alismatales is a hotspot for evolution of plant mitochondrial genomes characterized by remarkable differences in genome size, substitution rates, RNA editing, retrotranscription, gene loss and intron loss. Here we have sequenced the complete mitogenomes of <i>Zostera marina</i> and <i>Stratiotes aloides</i>, which together with previously sequenced mitogenomes from <i>Butomus</i> and <i>Spirodela</i>, provide new evolutionary evidence of genome size reduction, gene loss and transfer to the nucleus. The <i>Zostera</i> mitogenome includes a large portion of DNA transferred from the plastome, yet it is the smallest known mitogenome from a non-parasitic plant. Using a broad sample of the Alismatales, the evolutionary history of ribosomal protein gene loss is analyzed. In <i>Zostera</i> almost all ribosomal protein genes are lost from the mitogenome, but only some can be found in the nucleus.</p></div

Spatial and Functional Relationships Among Pol V-Associated Loci, Pol IV-Dependent siRNAs, and Cytosine Methylation in the \u3cem\u3eArabidopsis\u3c/em\u3e Epigenome

Multisubunit RNA polymerases IV and V (Pols IV and V) mediate RNA-directed DNA methylation and transcriptional silencing of retrotransposons and heterochromatic repeats in plants. We identified genomic sites of Pol V occupancy in parallel with siRNA deep sequencing and methylcytosine mapping, comparing wild-type plants with mutants defective for Pol IV, Pol V, or both Pols IV and V. Approximately 60% of Pol V-associated regions encompass regions of 24-nucleotide (nt) siRNA complementarity and cytosine methylation, consistent with cytosine methylation being guided by base-pairing of Pol IV-dependent siRNAs with Pol V transcripts. However, 27% of Pol V peaks do not overlap sites of 24-nt siRNA biogenesis or cytosine methylation, indicating that Pol V alone does not specify sites of cytosine methylation. Surprisingly, the number of methylated CHH motifs, a hallmark of RNA-directed de novo methylation, is similar in wild-type plants and Pol IV or Pol V mutants. In the mutants, methylation is lost at 50%–60% of the CHH sites that are methylated in the wild type but is gained at new CHH positions, primarily in pericentromeric regions. These results indicate that Pol IV and Pol V are not required for cytosine methyltransferase activity but shape the epigenome by guiding CHH methylation to specific genomic sites

Folded cavity SOI microring sensors for high sensitivity and real time measurement of biomolecular binding.

We demonstrate folded waveguide ring resonators for biomolecular sensing. We show that extending the ring cavity length increases the resonator quality factor, and thereby enhances the sensor resolution and minimum level of detection, while at the same time relaxing the tolerance on the coupling conditions to provide stable and large resonance contrast. The folded spiral path geometry allows a 1.2 mm long ring waveguide to be enclosed in a 150 microm diameter sensor area. The spiral cavity resonator is used to monitor the streptavidin protein binding with a detection limit of approximately 3 pg/mm(2), or a total mass of approximately 5 fg. The real time measurements are used to analyze the kinetics of biotin-streptavidin binding

Nucleation of PP-Branes and Fundamental Strings

We construct a solution to the low-energy string equations of motion in five dimensions that describes a circular loop of fundamental string exponentially expanding in a background electric $H$-field. Euclideanising this gives an instanton for the creation of a loop of fundamental string in a background $H$-field, and we calculate the rate of nucleation. Solutions describing magnetically charged strings and $p$-branes, where the gauge field comes from Kaluza-Klein reduction on a circle, are also constructed. It is known that a magnetic flux tube in four (reduced) spacetime dimensions is unstable to the pair creation of Kaluza-Klein monopoles. We show that in $(4+p)$ dimensions, magnetic $(p+1)$ ``fluxbranes" are unstable to the nucleation of a magnetically charged spherical $p$-brane. In ten dimensions the instanton describes the nucleation of a Ramond-Ramond magnetically charged six-brane in type IIA string theory. We also find static solutions describing spherical charged $p$-branes or fundamental strings held in unstable equilibrium in appropriate background fields. Instabilities of intersecting magnetic fluxbranes are also discussed.Comment: 28 pages, harvmac (b), reference added, typos correcte