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  • Differential effects of reactive nitrogen species on DNA base excision repair initiated by the alkyladenine DNA glycosylase. 19864471

    Chronic generation of reactive nitrogen species (RNS) can cause DNA damage and may also directly modify DNA repair proteins. RNS-modified DNA is repaired predominantly by the base excision repair (BER) pathway, which includes the alkyladenine DNA glycosylase (AAG). The AAG active site contains several tyrosines and cysteines that are potential sites for modification by RNS. In vitro, we demonstrate that RNS differentially alter AAG activity depending on the site and type of modification. Nitration of tyrosine 162 impaired 1,N(6)-ethenoadenine (epsilonA)-excision activity, whereas nitrosation of cysteine 167 increased epsilonA excision. To understand the effects of RNS on BER in vivo, we examined intestinal adenomas for levels of inducible nitric oxide synthase (iNOS) and AAG. A striking correlation between AAG and iNOS expression was observed (r = 0.76, P = 0.00002). Interestingly, there was no correlation between changes in AAG levels and enzymatic activity. We found AAG to be nitrated in human adenomas, suggesting that this RNS modification is relevant in the human disease. Expression of key downstream components of BER, apurinic/apyrimidinic endonuclease 1 (APE1) and DNA polymerase beta (POLbeta), was also examined. POLbeta protein was increased in nearly all adenomas compared with adjacent non-tumor tissues, whereas APE1 expression was only increased in approximately half of the adenomas and also was relocalized to the cytoplasm in adenomas. Collectively, the results suggest that BER is dysregulated in colon adenomas. RNS-induced posttranslational modification of AAG is one mechanism of BER dysregulation, and the type of modification may define the role of AAG during carcinogenesis.
    Tipo de documento:
    Referencia
    Referencia del producto:
    06-284
    Nombre del producto:
    Anti-Nitrotyrosine Antibody

  • High nitrogen insensitive 9 (HNI9)-mediated systemic repression of root NO3- uptake is associated with changes in histone methylation. 21788519

    In plants, root nitrate uptake systems are under systemic feedback repression by the N satiety of the whole organism, thus adjusting the N acquisition capacity to the N demand for growth; however, the underlying molecular mechanisms are largely unknown. We previously isolated the Arabidopsis high nitrogen-insensitive 9-1 (hni9-1) mutant, impaired in the systemic feedback repression of the root nitrate transporter NRT2.1 by high N supply. Here, we show that HNI9 encodes Arabidopsis INTERACT WITH SPT6 (AtIWS1), an evolutionary conserved component of the RNA polymerase II complex. HNI9/AtIWS1 acts in roots to repress NRT2.1 transcription in response to high N supply. At a genomic level, HNI9/AtIWS1 is shown to play a broader role in N signaling by regulating several hundred N-responsive genes in roots. Repression of NRT2.1 transcription by high N supply is associated with an HNI9/AtIWS1-dependent increase in histone H3 lysine 27 trimethylation at the NRT2.1 locus. Our findings highlight the hypothesis that posttranslational chromatin modifications control nutrient acquisition in plants.
    Tipo de documento:
    Referencia
    Referencia del producto:
    Múltiplo
    Nombre del producto:
    Múltiplo

  • Impaired transcriptional activity of Nrf2 in age-related myocardial oxidative stress is reversible by moderate exercise training. 23029187

    Aging promotes accumulation of reactive oxygen/nitrogen species (ROS/RNS) in cardiomyocytes, which leads to contractile dysfunction and cardiac abnormalities. These changes may contribute to increased cardiovascular disease in the elderly. Inducible antioxidant pathways are regulated by nuclear erythroid 2 p45-related factor 2 (Nrf2) through antioxidant response cis-elements (AREs) and are impaired in the aging heart. Whereas acute exercise stress (AES) activates Nrf2 signaling and promotes myocardial antioxidant function in young mice (~2 months), aging mouse (greater than 23 months) hearts exhibit significant oxidative stress as compared to those of the young. The purpose of this study was to investigate age-dependent regulation of Nrf2-antioxidant mechanisms and redox homeostasis in mouse hearts and the impact of exercise. Old mice were highly susceptible to oxidative stress following high endurance exercise stress (EES), but demonstrated increased adaptive redox homeostasis after moderate exercise training (MET; 10m/min, for 45 min/day) for ~6 weeks. Following EES, transcription and protein levels for most of the ARE-antioxidants were increased in young mice but their induction was blunted in aging mice. In contrast, 6-weeks of chronic MET promoted nuclear levels of Nrf2 along with its target antioxidants in the aging heart to near normal levels as seen in young mice. These observations suggest that enhancing Nrf2 function and endogenous cytoprotective mechanisms by MET, may combat age-induced ROS/RNS and protect the myocardium from oxidative stress diseases.
    Tipo de documento:
    Referencia
    Referencia del producto:
    AB9485
    Nombre del producto:
    Anti-Somatostatin Receptor Type 1 Antibody

  • High-performance liquid chromatography–ultrasonic nebulizer high-power nitrogen microwave-induced plasma mass spectrometry, real-time on-line coupling for selenium specia ... 15296393

    The coupling of a high-power nitrogen (N2) microwave-induced plasma (MIP) mass spectrometry – (MS) (1.3 kW) with high-performance liquid chromatography, connected with concentric nebulizer (CN), ultrasonic nebulizer (USN) and a hydride generation (HG) systems, for the optimization and determination of selenium compounds, has been carried out. The MIP-MS system fulfils the ideal requirement being an on-line real-time chromatographic detector for Se speciation analysis. Interchanging of MIP-MS system fabricated nebulizer (concentric) with an ultrasonic nebulizer increases about 3.4–12 (peak height) and 6.5–10 (peak area) times ion signals for the selenium compounds. The detection limits for selenate, selenite, trimethylselenonium ion (TmSe), selenomethionine (Semet) and selenoethionine (Seet) (in Milli-Q-water) obtained with the optimized HPLC–USN-N2MIP-MS system are 0.11, 0.14, 0.09, 0.14 and 0.10 µg L-1, respectively, about 12–48 times lower than the HPLC–CN-MIP-MS and 1.5–4.4 (peak height) times lower compared to the HPLC–CN-inductively coupled plasma (ICP)–MS coupling. Considering peak area, the repeatability (R.S.D. for three successive analyses) and intermediate precision (R.S.D. for three successive analyses performed on three different days), achieved for five Se compounds are 0.8–5.6, and 1.1–5.9%, comparable with the HPLC–CN-ICP-MS, HPLC–HG-MIP-MS and HPLC–CN-MIP-MS systems. The combined HPLC–USN-N2MIP-MS has been adequately applied for the determination of Se compounds in certified National Institute for Environmental studies human urine CRM No. 18. The results reasonably agree with the HPLC–CN-ICP-MS values. This encouraging combination may be an alternative ion source of mass spectrometry for coming generation in regard to the selenium speciation analysis.
    Tipo de documento:
    Referencia
    Referencia del producto:
    Múltiplo

  • Nucleosome positioning and histone H3 acetylation are independent processes in the Aspergillus nidulans prnD-prnB bidirectional promoter. 18296621

    In Aspergillus nidulans, proline can be used as a carbon and nitrogen source, and its metabolism requires the integration of three signals, including proline induction and nitrogen and carbon metabolite derepression. We have previously shown that the bidirectional promoter in the prnD-prnB intergenic region undergoes drastic chromatin rearrangements such that proline induction leads to the loss of positioned nucleosomes, whereas simultaneous carbon and nitrogen metabolite repression results in the partial repositioning of these nucleosomes. In the proline cluster, the inhibition of deacetylases by trichostatin A leads to partial derepression and is associated with a lack of nucleosome positioning. Here, we investigate the effect of histone acetylation in the proline cluster using strains deleted of essential components of putative A. nidulans histone acetyltransferase complexes, namely, gcnE and adaB, the orthologues of the Saccharomyces cerevisiae GCN5 and ADA2 genes, respectively. Surprisingly, GcnE and AdaB are not required for transcriptional activation and chromatin remodeling but are required for the repression of prnB and prnD and for the repositioning of nucleosomes in the divergent promoter region. Chromatin immunoprecipitation directed against histone H3 lysines K9 and K14 revealed that GcnE and AdaB participate in increasing the acetylation level of at least one nucleosome in the prnD-prnB intergenic region during activation, but these activities do not determine nucleosome positioning. Our results are consistent with a function of GcnE and AdaB in gene repression of the proline cluster, probably an indirect effect related to the function of CreA, the DNA-binding protein mediating carbon catabolite repression in A. nidulans.
    Tipo de documento:
    Referencia
    Referencia del producto:
    06-599
    Nombre del producto:
    Anti-acetyl-Histone H3 Antibody

  • Branched-chain amino acids and neurotransmitter metabolism: expression of cytosolic branched-chain aminotransferase (BCATc) in the cerebellum and hippocampus. 15329886

    In the brain, catabolism of the branched-chain amino acids (BCAAs) provides nitrogen for the synthesis of glutamate and glutamine. Glutamate is formed through transfer of an amino group from BCAA to alpha-ketoglutarate in reaction catalyzed by branched-chain aminotransferases (BCAT). There are two isozymes of BCAT: cytosolic BCATc, which is found in the nervous system, ovary, and placenta, and mitochondrial BCATm, which is found in all organs except rat liver. In cell culture systems, BCATc is found only in neurons and developing oligodendrocytes, whereas BCATm is the isoform in astroglia. In this study, we used immunohistochemistry to examine the distribution of BCATc in the rat brain, focusing on the well-known neural architecture of the cerebellum and hippocampus. We show that BCATc is expressed only in neurons in the adult rat brain. In glutamatergic neurons such as granule cells of the cerebellar cortex and of the dentate gyrus, BCATc is localized to axons and nerve terminals. In contrast, in GABAergic neurons such as cerebellar Purkinje cells and hippocampal pyramidal basket cells, BCATc is concentrated in cell bodies. A common function for BCATc in these neurotransmitter systems may be to modulate amounts of glutamate available either for release as neurotransmitter or for use as precursor for synthesis of GABA. Particularly striking in our findings is the strong expression of BCATc in the mossy fiber pathway of the hippocampal formation. This result is discussed in light of the effectiveness of the anticonvulsant drug gabapentin, which is a specific inhibitor of BCATc.
    Tipo de documento:
    Referencia
    Referencia del producto:
    MAB5406
    Nombre del producto:
    Anti-GAD67 Antibody, clone 1G10.2

  • Doxycycline loaded poly(ethylene glycol) hydrogels for healing vesicant-induced ocular wounds. 19853296

    Half mustard (CEES) and nitrogen mustard (NM) are commonly used surrogates and vesicant analogs of the chemical warfare agent sulfur mustard. In the current study, in situ forming poly(ethylene glycol) (PEG)-based doxycycline hydrogels are developed and evaluated for their wound healing efficacy in CEES and NM-exposed rabbit corneas in organ culture. The hydrogels, characterized by UV-Vis spectrophotometry, rheometry, and swelling kinetics, showed that the hydrogels are optically transparent, have good mechanical strength and a relatively low degree of swelling (<7%). In vitro doxycycline release from the hydrogel disks (0.25% w/v) was found to be biphasic with release half times of approximately 12 and 72h, respectively, with 80-100% released over a 7-day period. Permeation of doxycycline through vesicant wounded corneas was found to be 2.5 to 3.4 fold higher than non-wounded corneas. Histology and immunofluorescence studies showed a significant reduction of matrix metalloproteinase-9 (MMP-9) and improved healing of vesicant-exposed corneas by doxycycline hydrogels compared to a similar dose of doxycycline delivered in phosphate buffered saline (PBS, pH 7.4). In conclusion, the current studies demonstrate that the doxycycline-PEG hydrogels accelerate corneal wound healing after vesicant injury offering a therapeutic option for ocular mustard injuries.
    Tipo de documento:
    Referencia
    Referencia del producto:
    MAB3309

  • Apc10 and Ste9/Srw1, two regulators of the APC-cyclosome, as well as the CDK inhibitor Rum1 are required for G1 cell-cycle arrest in fission yeast. 9736616

    Many eukaryotic cells arrest the cell cycle at G1 phase upon nutrient deprivation. In fission yeast, during nitrogen starvation, cells divide twice and arrest at G1. We have isolated a novel type of sterile mutant, which undergoes one additional S phase upon starvation and, as a result, arrests at G2. Three loci (apc10, ste9/srw1 and rum1) were identified. The apc10 mutants, previously unidentified, show, in addition to sterility, temperature-sensitive growth with defects in chromosome segregation. apc10(+) is essential for viability, encodes a conserved protein (a homologue of budding yeast Apc10/Doc1) and is required for ubiquitination and degradation of mitotic B-type cyclins. Apc10 does not co-sediment with the 20S APC-cyclosome, a ubiquitin ligase for B-type cyclins, and in the apc10 mutant the 20S complex is intact, suggesting that it is a novel regulator for this complex. A subpopulation of Apc10 does co-immunoprecipitate with the anaphase-promoting complex (APC). A second gene, ste9(+)/srw1(+), encodes a member of the fizzy-related family, also regulators of the APC. Finally, Rum1 is a cyclin-dependent kinase (CDK) inhibitor which exists only in G1. The results suggest that dual downregulation of CDK, one via the APC and the other via the CDK inhibitor, is a universal mechanism that is used to arrest cell cycle progression at G1.
    Tipo de documento:
    Referencia
    Referencia del producto:
    MAB1510