Methane undergoes highly facile C-H bond cleavage on the stoichiometric IrO(110) surface. From temperature-programmed reaction spectroscopy experiments, we found that methane molecularly adsorbed as a strongly bound σ complex on IrO(110) and that a large fraction of the adsorbed complexes underwent C-H bond cleavage at temperatures as low as 150 kelvin (K). The initial dissociation probability of methane on IrO(110) decreased from 80 to 20% with increasing surface temperature from 175 to 300 K. We estimate that the activation energy for methane C-H bond cleavage is 9.5 kilojoule per mole (kJ/mol) lower than the binding energy of the adsorbed precursor on IrO(110), and equal to a value of ~28.5 kJ/mol. Low-temperature activation may avoid unwanted side reactions in the development of catalytic processes to selectively convert methane to value-added products.

Early biochemical studies of viral replication suggested that most viruses produce double-stranded RNA (dsRNA), which is essential for the induction of the host immune response. However, it was reported in 2006 that dsRNA could be detected by immunofluorescence antibody staining in double-stranded DNA and positive-strand RNA virus infections but not in negative-strand RNA virus infections. Other reports in the literature seemed to support these observations. This suggested that negative-strand RNA viruses produce little, if any, dsRNA or that more efficient viral countermeasures to mask dsRNA are mounted. Because of our interest in the use of dsRNA antibodies for virus discovery, particularly in pathological specimens, we wanted to determine how universal immunostaining for dsRNA might be in animal virus infections. We have detected the in situ formation of dsRNA in cells infected with vesicular stomatitis virus, measles virus, influenza A virus, and Nyamanini virus, which represent viruses from different negative-strand RNA virus families. dsRNA was also detected in cells infected with lymphocytic choriomeningitis virus, an ambisense RNA virus, and minute virus of mice (MVM), a single-stranded DNA (ssDNA) parvovirus, but not hepatitis B virus. Although dsRNA staining was primarily observed in the cytoplasm, it was also seen in the nucleus of cells infected with influenza A virus, Nyamanini virus, and MVM. Thus, it is likely that most animal virus infections produce dsRNA species that can be detected by immunofluorescence staining. The apoptosis induced in several uninfected cell lines failed to upregulate dsRNA formation. IMPORTANCEAn effective antiviral host immune response depends on recognition of viral invasion and an intact innate immune system as a first line of defense. Double-stranded RNA (dsRNA) is a viral product essential for the induction of innate immunity, leading to the production of type I interferons (IFNs) and the activation of hundreds of IFN-stimulated genes. The present study demonstrates that infections, including those by ssDNA viruses and positive-and negative-strand RNA viruses, produce dsRNAs detectable by standard immunofluorescence staining. While dsRNA staining was primarily observed in the cytoplasm, nuclear staining was also present in some RNA and DNA virus infections. The nucleus is unlikely to have pathogen-associated molecular pattern (PAMP) receptors for dsRNA because of the presence of host dsRNA molecules. Thus, it is likely that most animal virus infections produce dsRNA species detectable by immunofluorescence staining, which may prove useful in viral discovery as well.A n effective antiviral host response depends on recognition of viral invasion and an intact innate immune system as a first line of defense. Although the mammalian innate immune system responds to other pathogens, the emphasis here is on animal viruses. Double-stranded RNA (dsRNA) is a viral product essential in the induction of innate immunity, leading to the production of type I interferons (IFNs...

We investigated the oxidation of CH4 on oxygen-pre-covered IrO2(110) surfaces using temperature-programmed reaction spectroscopy (TPRS) and density functional theory (DFT). Our TPRS results show that on-top oxygen (Oot) species hinder CH4 adsorption, providing evidence that CH4 adsorbs on coordinatively unsaturated Ir atoms. We also find that the fractional yield of adsorbed CH4 that reacts during TPRS remains constant at ∼70% as the Oot-coverage increases to about 0.5 monolayer for saturation CH4 coverage, demonstrating that O-rich IrO2(110) surfaces are highly active in promoting CH4 C–H bond cleavage. Our results show that Oot atoms promote CH4 oxidation to CO2 as well as H2O formation while suppressing CO and recombinative CH4 desorption, as evidenced by an increase in the fractional yield of CO2 produced during TPRS and a downshift of CO2 and H2O TPRS peak maxima with increasing Oot-coverage. DFT predicts that initial CH4 bond cleavage is highly facile on both stoichiometric and O-rich IrO2(110) and can occur by either H-transfer to an Oot or a bridging O-atom of the surface. Our calculations also predict that oxidation of the CH x species that result from CH4 activation is more facile on O-rich compared with stoichiometric IrO2(110), and that complete oxidation is strongly favored on the O-rich surface, in good agreement with our experimental findings. According to the calculations, key steps in the CH4 oxidation pathway have significantly lower-energy barriers on O-rich vs stoichiometric IrO2(110) because these steps involve reaction with Oot atoms initially present on the surface rather than the abstraction of more strongly bound Obr species. High coverages of O-atoms also enable adsorbed intermediates to oxidize extensively on O-rich IrO2(110), without the intermediates needing to overcome diffusion barriers to access reactive O-atoms. Our results provide insights for understanding CH4 oxidation on IrO2(110) surfaces under reaction conditions at which Oot atoms and adsorbed CH4 can co-exist.

Epithelial tubes are the functional units of many organs, but little is known about how tube sizes are established. Using the Drosophila tracheal system as a model, we previously showed that mutations in varicose (vari) cause tubes to become elongated without increasing cell number. Here we show vari is required for accumulation of the tracheal size-control proteins Vermiform and Serpentine in the tracheal lumen. We also show that vari is an essential septate junction (SJ) gene encoding a membrane associated guanylate kinase (MAGUK). In vivo analyses of domains important for MAGUK scaffolding functions demonstrate that while the Vari HOOK domain is essential, the L27 domain is dispensable. Phylogenetic analyses reveal that Vari helps define a new MAGUK subgroup that includes mammalian PALS2. Importantly, both Vari and PALS2 are basolateral, and the interaction of Vari with the cell-adhesion protein Neurexin IV parallels the interaction of PALS2 and another cell-adhesion protein, Necl-2. Vari therefore bolsters the similarity between Drosophila and vertebrate epithelial basolateral regions, which had previously been limited to the common basolateral localization of Scrib, Dlg and Lgl, proteins required for epithelial polarization at the beginning of embryogenesis. However, by contrast to Scrib, Dlg and Lgl, Vari is not required for cell polarity but rather is part of a cell-adhesion complex. Thus, Vari fundamentally extends the similarity of Drosophila and vertebrate basolateral regions from sharing only polarity complexes to sharing both polarity and cell-adhesion complexes.

We investigated the adsorption and oxidation of H 2 on O-rich IrO 2 (110) using temperature programmed reaction spectroscopy (TPRS) and density functional theory (DFT) calculations. Our results show that H 2 dissociation occurs efficiently on O-rich IrO 2 (110) at low temperature and initiates from an adsorbed H 2 σ-complex on the coordinatively-unsaturated Ir atoms (Ir cus ). We find that on-top oxygen atoms (O ot ), adsorbed on the Ir cus sites, promote the desorption-limited evolution of H 2 O during subsequent oxidation of the adsorbed hydrogen on IrO 2 ( 110) while suppressing reaction-limited production of H 2 O via the recombination of bridging HO groups (HO br ) (~500 to 750 K) during TPRS. The desorption-limited TPRS peak of H 2 O shifts from~490 to 550 K with increasing O ot coverage, demonstrating that O ot atoms stabilize adsorbed OH and H 2 O species. DFT predicts that molecularly-adsorbed H 2 dissociates on O-rich IrO 2 (110) at low temperature and that the resulting H-atoms redistribute to produce a mixture of HO br and HO ot groups, with equilibrium favouring HO ot groups. Our calculations further predict that subsequent H 2 O evolution occurs through the recombination of HO br /HO ot and HO ot /HO ot pairs, and that these reactions represent desorption-limited pathways because the dissociative chemisorption of H 2 O is favoured over molecular adsorption on IrO 2 (110). The higher stability of HO ot groups and their preferred formation causes the higher-barrier HO ot /HO ot recombination reaction to become the dominant pathway for H 2 O formation with increasing O ot coverage, consistent with the experimentally-observed upshift in the H 2 O TPRS peak temperature.

The Cardiovirus genus of the family Picornaviridae includes two distinct species, Encephalomyocarditis virus and Theilovirus. We now report the complete nucleotide sequences of three Theiler's murine encephalomyelitis virus ( Encephalomyocarditis virus (EMCV) and Theilovirus are two distinct species in the Cardiovirus genus of the family Picornaviridae (52). The EMCVs comprise a single serotype and have a wide host range (64), while the Theilovirus species, until recently, included two serotypes, Theiler's murine encephalomyelitis virus (TMEV) and Vilyuisk human encephalomyelitis virus (VHEV), which appear to have much narrower host ranges than EMCV. The nucleotides of the RNA genomes of EMCV and TMEV are ϳ58% identical, and the amino acids of their polyproteins are ϳ50% identical. The amino acids of the capsid regions of TMEV and EMCV show the highest level of identity (ϳ62%), resulting in their cross-reactivity in serological tests measuring broad antigenicity (complement fixation [CF] and enzyme-linked immunosorbent assays) but not in virus neutralization (VN) assays.TMEVs were originally isolated from mice (54) and later from rats (18). Serological studies indicate that the feral house mouse Mus musculus is the natural host for TMEV (10, 29). In the early 1930s, TMEVs were isolated from colony-bred mice that developed spontaneous paralysis (54, 55). Based on the flaccid paralysis observed, indicative of the involvement of anterior horn cells or motor neurons, and on the revealed pathological changes of degenerating anterior horn cells, accompanied by microglial proliferation, these viruses were originally referred to as mouse polioviruses (41). In contrast to the strict motor neuron-trophic nature of human poliovirus in mice (21) and humans, TMEVs target both the anterior (motor) and posterior (sensory) neurons in the gray matter of the spinal cord (2, 27, 50). However, TMEVs are enteric pathogens that cause primarily asymptomatic infections of the digestive tract in colony-bred (nonbarrier) mice, and the spread of the virus to the mouse central nervous system (CNS) is rare.

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We report new w À fluorescent balancers scorable from stage 13 through adulthood that bear a nuclearlocalized yellow fluorescent protein marker directly driven by dfd and GMR enhancer elements. The utility of this marker is enhanced by identification of an anti-GFP/yellow fluorescent protein (YFP) serum that is compatible with heat fixation.