Ultrathin Co3O4 Layers with Large Contact Area on Carbon Fibers as High‐Performance Electrode for Flexible Zinc–Air Battery Integrated with Flexible Display

A facile and binder‐free method is developed for the in situ and horizontal growth of ultrathin mesoporous Co₃O₄ layers on the surface of carbon fibers in the carbon cloth (ultrathin Co₃O₄/CC) as high‐performance air electrode for the flexible Zn–air battery. In particular, the ultrathin Co₃O₄ layers have a maximum contact area on the conductive support, facilitating the rapid electron transport and preventing the aggregation of ultrathin layers. The ultrathin feature of Co₃O₄ layers is characterized by the transmission electron microscopy, Raman spectra, and X‐ray absorption fine structure spectroscopy. Benefiting from the high utilization degree of active materials and rapid charge transport, the mass activity for oxygen reduction and evolution reactions of the ultrathin Co₃O₄/CC electrode is more than 10 times higher than that of the carbon cloth loaded with commercial Co₃O₄ nanoparticles. Compared to the commercial Co₃O₄/CC electrode, the flexible Zn–air battery using ultrathin Co₃O₄/CC electrode exhibits excellent rechargeable performance and high mechanical stability. Furthermore, the flexible Zn–air battery is integrated with a flexible display unit. The whole integrated device can operate without obvious performance degradation under serious deformation and even during the cutting process, which makes it highly promising for wearable and roll‐up optoelectronics.     

Synthesis, antiproliferative, and vasorelaxing evaluations of coumarin alpha-methylene-gamma-butyrolactones

Certain coumarin alpha-methylene-gamma-butyrolactones were synthesized and evaluated for antiproliferative and vasorelaxing activities. These compounds were synthesized via alkylation of hydroxycoumarins 2a-f followed by oxidation and the Reformatsky-type condensation. The results of this study are as follows (1) for the vasorelaxing activity, coumarin-7-yl alpha-methylene-gamma-butyrolactone 6d, with an IC50 value of 9.4 microM against pig coronary arterial contraction induced by KCl, is a more active vasorelaxant than its coumarin-4-yl counterpart 6a and its gamma-methyl congener 1. A methyl group substituted at C-4 of the coumarin-7-yl moiety reduced the vasorelaxing effect (6d vs 6e) while the 3,4,8-trimethyl derivative 6f was inactive. (2) For the antiproliferative activity, coumarin-4-yl alpha-methylene-gamma-butyrolactone 6a, which exhibited the most potent antiproliferative activity on the growth of MCF7, NCI-H460, and SF-268 with IC50 values of 6.97, 14.68, and 8.36 microM, respectively, is more cytotoxic than its coumarin-7-yl counterpart 6d and the 6,7-dimethyl derivative 6b. For the coumarin-7-yl derivatives, 6d is more active than its gamma-methyl congener 1, indicating that substitution at the gamma-position decreased cytotoxicity.     

Site-directed gene replacement of the phytopathogen Xanthomonas axonopodis pv. citri

In this work we defined experimental conditions for site-directed gene replacement of the Xanthomonas axonopodis pv. citri (Xac), an economically relevant pathogen of citrus plants. The procedure involved, first, optimizing the electrotransformation conditions of the Xac 306 strain and, second, constructing non-replicative suicide vectors carrying knockout copies of the target gene. Using specific experimental conditions, transformation efficiencies of Xac were at least 100 fold higher than those achieved with electroporation protocols previously designed for X. campestris transformation. Successful gene replacement events were achieved with a suicide vector derived from R6K plasmid (pWR-SS) but not with those with ColE1 replication origin. We have chosen the oppA as a target gene, encoding the binding component (OppA) of the major oligopeptide uptake system found in the genome of the Xac 306 strain, although not in X. campestris pv. campestris (Xcc). Defining the experimental conditions, which allow for the specific mutagenesis of the Xac 306 strain, represents a step in the understanding of both genetics and physiology of this economically important bacterial species.     

The molybdate-binding protein (ModA) of the plant pathogen Xanthomonas axonopodis pv. citri

The modABC operon of phytopathogen Xanthomonas axonopodis pv. citri (X. citri) encodes a putative ABC transporter involved in the uptake of the molybdate and tungstate anions. Sequence analyses showed high similarity values of ModA orthologs found in X. campestris pv. campestris (X. campestris) and Escherichia coli. The X. citri modA gene was cloned in pET28a and the recombinant protein, expressed in the E. coli BL21 (DE3) strain, purified by immobilized metal affinity chromatography. The purified protein remained soluble and specifically bound molybdate and tungstate with K(d) 0.29+/-0.12 microM and 0.58+/-0.14 microM, respectively. Additionally binding of molybdate drastically enhanced the thermal stability of the recombinant ModA as compared to the apoprotein. This is the first characterization of a ModA ortholog expressed by a phytopathogen and represents an important tool for functional, biochemical and structural analyses of molybdate transport in Xanthomonas species.     

Drosophila Perilipin/ADRP homologue Lsd2 regulates lipid metabolism

Many cells store neutral lipids, as triacylglycerol and sterol esters, in droplets. PAT-domain proteins form a conserved family of proteins that are localized at the surface of neutral lipid droplets. Two mammalian members of this family, Perilipin and adipose differentiation-related protein, are involved in lipid storage and regulate lipolysis. Here, we describe the Drosophila PAT-family member Lsd2. We showed that Lsd2 is predominantly expressed in tissues engaged in high levels of lipid metabolism, the fat body and the germ line of females. Ultrastructural analysis in the germ line showed that Lsd2 localizes to the surface of lipid droplets. We have generated an Lsd2 mutant and described its phenotype. Mutant adults have a reduced level of neutral lipid content compared to wild type, showing that Lsd2 is required for normal lipid storage. In addition, ovaries from Lsd2 mutant females exhibit an abnormal pattern of accumulation of neutral lipids from mid-oogenesis, which results in reduced deposition of lipids in the egg. Consistent with its expression in the female germ line, we showed that Lsd2 is a maternal effect gene that is required for normal embryogenesis. This work demonstrates that Lsd2 has an evolutionarily conserved function in lipid metabolism and establishes Drosophila melanogaster as a new in vivo model for studies on the PAT-family of proteins.     

Lysogenic Streptococcus suis Isolate SS2-4 Containing Prophage SMP Showed Increased Mortality in Zebra Fish Compared to the Wild-Type Isolate

Streptococcus suis (S. suis) infection is considered to be a major problem in the swine industry worldwide. Based on the capsular type, 33 serotypes of S. suis have been described, with serotype 2 (SS2) being the most frequently isolated from diseased piglets. Little is known, however, about the pathogenesis and virulence factors of S. suis. Research on bacteriophages highlights a new area in S. suis research. A S. suis serotype 2 bacteriophage, designated SMP, has been previously isolated in our laboratory. Here, we selected a lysogenic isolate in which the SMP phage was integrated into the chromosome of strain SS2-4. Compared to the wild-type isolate, the lysogenic strain showed increased mortality in zebra fish. Moreover the sensitivity of the lysogenic strain to lysozyme was seven times higher than that of the wild-type.     

Silencing Mutant Ataxin-3 Rescues Motor Deficits and Neuropathology in Machado-Joseph Disease Transgenic Mice

Machado-Joseph disease (MJD) or spinocerebellar ataxia type 3 (SCA3) is an autosomal dominantly-inherited neurodegenerative disorder caused by the over-repetition of a CAG codon in the MJD1 gene. This expansion translates into a polyglutamine tract that confers a toxic gain-of-function to the mutant protein – ataxin-3, leading to neurodegeneration in specific brain regions, with particular severity in the cerebellum. No treatment able to modify the disease progression is available. However, gene silencing by RNA interference has shown promising results. Therefore, in this study we investigated whether lentiviral-mediated allele-specific silencing of the mutant ataxin-3 gene, after disease onset, would rescue the motor behavior deficits and neuropathological features in a severely impaired transgenic mouse model of MJD. For this purpose, we injected lentiviral vectors encoding allele-specific silencing-sequences (shAtx3) into the cerebellum of diseased transgenic mice expressing the targeted C-variant of mutant ataxin-3 present in 70% of MJD patients. This variation permits to discriminate between the wild-type and mutant forms, maintaining the normal function of the wild-type allele and silencing only the mutant form. Quantitative analysis of rotarod performance, footprint and activity patterns revealed significant and robust alleviation of gait, balance (average 3-fold increase of rotarod test time), locomotor and exploratory activity impairments in shAtx3-injected mice, as compared to control ones injected with shGFP. An important improvement of neuropathology was also observed, regarding the number of intranuclear inclusions, calbindin and DARPP-32 immunoreactivity, fluorojade B and Golgi staining and molecular and granular layers thickness. These data demonstrate for the first time the efficacy of gene silencing in blocking the MJD-associated motor-behavior and neuropathological abnormalities after the onset of the disease, supporting the use of this strategy for therapy of MJD.     

Analysis of FGF-Dependent and FGF-Independent Pathways in Otic Placode Induction

The inner ear develops from a patch of thickened cranial ectoderm adjacent to the hindbrain called the otic placode. Studies in a number of vertebrate species suggest that the initial steps in induction of the otic placode are regulated by members of the Fibroblast Growth Factor (FGF) family, and that inhibition of FGF signaling can prevent otic placode formation. To better understand the genetic pathways activated by FGF signaling during otic placode induction, we performed microarray experiments to estimate the proportion of chicken otic placode genes that can be up-regulated by the FGF pathway in a simple culture model of otic placode induction. Surprisingly, we find that FGF is only sufficient to induce about 15% of chick otic placode-specific genes in our experimental system. However, pharmacological blockade of the FGF pathway in cultured chick embryos showed that although FGF signaling was not sufficient to induce the majority of otic placode-specific genes, it was still necessary for their expression in vivo. These inhibitor experiments further suggest that the early steps in otic placode induction regulated by FGF signaling occur through the MAP kinase pathway. Although our work suggests that FGF signaling is necessary for otic placode induction, it demonstrates that other unidentified signaling pathways are required to co-operate with FGF signaling to induce the full otic placode program.     

Nitric oxide and cell death in liver cancer cells

Nitric oxide (NO) is a lipophillic, highly diffusible, and short-lived physiological messenger which regulates a variety of physiopathological responses. NO may exert its cellular action through cGMP-dependent and cGMP-independent pathways which includes different postranslational modifications. The effect of NO in cancer depends on the activity and localization of NOS isoforms, concentration and duration of NO exposure, cellular sensitivity, and hypoxia/re-oxygenation process. NO regulates critical factors such as the hypoxia inducible factor-1 (HIF-1) and p53 generally leading to growth arrest, apoptosis or adaptation. NO sensitizes hepatoma cells to chemotherapeutic compounds probably through increased p53 and cell death receptor expressions.