Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 54
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Biodivers Data J ; 9: e67616, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34316271

RESUMO

Background: The herbarium of the South-Siberian Botanical Garden of Altai State University (ALTB) houses the largest collection of plants from the Altai Mountain Country (AMC), an area that extends across Russia, Kazakhstan, Mongolia and China. The collection of ALTB includes more than 450,00 specimens, making it the seventh largest in Russia and the fourth largest amongst Russian university herbaria. Altai State University (ASU), the home of ALTB, is one of the most important centres of academic education and research in Siberia and the Russian Far East. It is a sociocultural centre that provides a distinguished learning environment for undergraduate and graduate students in many scholarly and professional fields, meeting the needs of today's knowledge-based post-industrial society and contributing to regional development. It actively promotes international cooperation and strategic collaboration amongst countries of the AMC in the fields of science, education and culture. In particular, the activities of the South-Siberian Botanical Garden include: development of measures to protect rare and endangered plant species, research on the flora and vegetation of the AMC, preparation and publication of a multi-volume work "Flora Altaica", monographic study of individual plant groups, conducting laboratory classes, summer practicals and special courses. The main purpose of this article is to attract the attention of the scientific community to the botanical research of transboundary territory of the Altai Mountain Country (Russia, Kazakhstan, China and Mongolia) and to the future development of digital plant collections in partnership with Global Biodiversity Information Facility (GBIF). New information: The Virtual Herbarium ALTB (Russian interface - altb.asu.ru) is the largest digital collection of plants from the transboundary territory of the Altai Mountain Country and the main source of primary material for the "Flora Altaica" project (http://altaiflora.asu.ru/en/). Since 2017, when Altai State University became a GBIF data publisher, data from the Virtual Herbarium ALTB has been exported to the dataset "Virtual Herbarium ALTB (South-Siberian Botanical Garden)" in GBIF. Currently, it includes images and data from 22,466 vascular plants, of which 67% have geographic coordinates (accessed on 30.03.2021). Most of the specimens have been collected since 1977, with the most intensive collecting years being 1995-2008. In 2019, the label-data table of the Virtual Herbarium ALTB was modified to bring it into conformity with the Darwin Core specification (http://altb.asu.ru/). This effectively solved the major impediment to sharing plant diversity data from the AMC and adjacent regions in a multilingual environment.

2.
Nat Commun ; 12(1): 2624, 2021 05 11.
Artigo em Inglês | MEDLINE | ID: mdl-33976143

RESUMO

The etiology of ulcerative colitis is poorly understood and is likely to involve perturbation of the complex interactions between the mucosal immune system and the commensal bacteria of the gut, with cytokines acting as important cross-regulators. Here we use IFN receptor-deficient mice in a dextran sulfate sodium (DSS) model of acute intestinal injury to study the contributions of type I and III interferons (IFN) to the initiation, progression and resolution of acute colitis. We find that mice lacking both types of IFN receptors exhibit enhanced barrier destruction, extensive loss of goblet cells and diminished proliferation of epithelial cells in the colon following DSS-induced damage. Impaired mucosal healing in double IFN receptor-deficient mice is driven by decreased amphiregulin expression, which IFN signaling can up-regulate in either the epithelial or hematopoietic compartment. Together, these data underscore the pleiotropic functions of IFNs and demonstrate that these critical antiviral cytokines also support epithelial regeneration following acute colonic injury.


Assuntos
Colite Ulcerativa/imunologia , Interferons/metabolismo , Mucosa Intestinal/patologia , Reepitelização/imunologia , Animais , Colite Ulcerativa/induzido quimicamente , Colite Ulcerativa/patologia , Sulfato de Dextrana/administração & dosagem , Sulfato de Dextrana/toxicidade , Modelos Animais de Doenças , Células Epiteliais , Feminino , Humanos , Mucosa Intestinal/efeitos dos fármacos , Mucosa Intestinal/imunologia , Masculino , Camundongos , Camundongos Knockout , Receptor de Interferon alfa e beta/genética , Receptor de Interferon alfa e beta/metabolismo , Receptores de Interferon/genética , Receptores de Interferon/metabolismo , Transdução de Sinais/genética , Transdução de Sinais/imunologia , Organismos Livres de Patógenos Específicos
3.
PLoS One ; 15(8): e0231560, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32822353

RESUMO

The dehydroshikimate dehydratase (DSD) from Corynebacterium glutamicum encoded by the qsuB gene is related to the previously described QuiC1 protein (39.9% identity) from Pseudomonas putida. Both QuiC1 and QsuB are two-domain bacterial DSDs. The N-terminal domain provides dehydratase activity, while the C-terminal domain has sequence identity with 4-hydroxyphenylpyruvate dioxygenase. Here, the QsuB protein and its N-terminal domain (N-QsuB) were expressed in the T7 system, purified and characterized. QsuB was present mainly in octameric form (60%), while N-QsuB had a predominantly monomeric structure (80%) in aqueous buffer. Both proteins possessed DSD activity with one of the following cofactors (listed in the order of decreasing activity): Co2+, Mg2+, Mn2+. The Km and kcat values for the QsuB enzyme (Km ~ 1 mM, kcat ~ 61 s-1) were two and three times higher than those for N-QsuB. 3,4-DHBA inhibited QsuB (Ki ~ 0.38 mM, Ki' ~ 0.96 mM) and N-QsuB (Ki ~ 0.69 mM) enzymes via mixed and noncompetitive inhibition mechanism, respectively. E. coli MG1655ΔaroEPlac‒qsuB strain produced three times more 3,4-DHBA from glucose in test tube fermentation than the MG1655ΔaroEPlac‒n-qsuB strain. The C-terminal domain activity towards 3,4-DHBA was not established in vitro. This domain was proposed to promote protein oligomerization for maintaining structural stability of the enzyme. The dimer formation of QsuB protein was more predictable (ΔG = ‒15.8 kcal/mol) than the dimerization of its truncated version N-QsuB (ΔG = ‒0.4 kcal/mol).


Assuntos
Biotecnologia , Corynebacterium glutamicum/enzimologia , Hidroliases/metabolismo , Hidroxibenzoatos/metabolismo , Corynebacterium glutamicum/genética , DNA Recombinante/genética , Escherichia coli/metabolismo , Hidroliases/química , Hidroliases/genética , Concentração de Íons de Hidrogênio , Modelos Moleculares , Domínios Proteicos , Multimerização Proteica , Estrutura Quaternária de Proteína
4.
Biochem Biophys Res Commun ; 506(4): 1013-1018, 2018 12 02.
Artigo em Inglês | MEDLINE | ID: mdl-30404736

RESUMO

Advanced glycation end-products (AGEs) play a pivotal role in macro- and micro-vascular diabetic complications. We investigated the mechanism by which methylglyoxal (an endogenous generator of AGEs) affects vascular contractility using the isolated artery technique. Contractile responses to vasoconstrictors phenylephrine (PE), angiotensin II (Ang II), vasopressin (VP) and KCl were measured in the isolated rat aorta following one-our exposure to methylglyoxal (50-200 µM). The perfused rat kidney was employed to confirm the effect of methylglyoxal on microvessels. Methylglyoxal-induced changes in cytosolic calcium were measured in the smooth muscle layer of the aorta with the calcium-sensing fluorophore Fluo-4 AM. Methylglyoxal significantly increased maximal contraction of the rat aorta to PE, Ang II and VP. Similar results were seen in response to the depolarizing vasoconstrictor KCl in macro and micro vessels. The methylglyoxal-induced increases in aortic contraction mediated by the agonist and KCl were endothelium independent. Methylglyoxal-induced increases in KCl-dependent aortic contraction were abolished after the removal of extracellular calcium or in the presence of the calcium channel blocker nifedipine. Incubation with the antioxidant N-acetyl-l-cysteine (NAC), apocynin (a nonselective NADPH oxidase (NOX) inhibitor) or chelerythrine (a protein kinase C (PKC) inhibitor) prior to methylglyoxal pre-treatment reversed the methylglyoxal-induced increases in the rat aortic contractility. In conclusion, the formation of AGEs increases vasoconstriction of both macro- and micro-vessels by increasing the voltage-activated calcium entry in vascular smooth muscles in a NOX and PKC dependent manner.


Assuntos
Cálcio/metabolismo , NADPH Oxidases/metabolismo , Proteína Quinase C/metabolismo , Aldeído Pirúvico/farmacologia , Vasoconstrição , Acetofenonas/farmacologia , Acetilcisteína/farmacologia , Animais , Aorta/efeitos dos fármacos , Aorta/metabolismo , Benzofenantridinas/farmacologia , Endotélio Vascular/efeitos dos fármacos , Endotélio Vascular/metabolismo , Ativação Enzimática/efeitos dos fármacos , Rim/efeitos dos fármacos , Masculino , Cloreto de Potássio/farmacologia , Inibidores de Proteínas Quinases/farmacologia , Ratos Wistar , Vasoconstrição/efeitos dos fármacos
5.
J Immunol ; 201(7): 2082-2093, 2018 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-30111632

RESUMO

Crystal structure of the ternary complex of human IL-24 with two receptors, IL-22R1 and IL-20R2, has been determined at 2.15 Å resolution. A crystallizable complex was created by a novel approach involving fusing the ligand with a flexible linker to the presumed low-affinity receptor, and coexpression of this construct in Drosophila S2 cells together with the presumed high-affinity receptor. This approach, which may be generally applicable to other multiprotein complexes with low-affinity components, was necessitated by the instability of IL-24 expressed by itself in either bacteria or insect cells. Although IL-24 expressed in Escherichia coli was unstable and precipitated almost immediately upon its refolding and purification, a small fraction of IL-24 remaining in the folded state was shown to be active in a cell-based assay. In the crystal structure presented here, we found that two cysteine residues in IL-24 do not form a predicted disulfide bond. Lack of structural restraint by disulfides, present in other related cytokines, is most likely reason for the low stability of IL-24. Although the contact area between IL-24 and IL-22R1 is larger than between the cytokine and IL-20R2, calculations show the latter interaction to be slightly more stable, suggesting that the shared receptor (IL-20R2) might be the higher-affinity receptor.


Assuntos
Interleucinas/metabolismo , Complexos Multiproteicos/metabolismo , Receptores de Interleucina/metabolismo , Animais , Linhagem Celular , Cristalografia por Raios X , Citocinas , Drosophila , Humanos , Ligação Proteica , Conformação Proteica , Domínios Proteicos/genética , Receptores de Interleucina/genética , Transdução de Sinais
6.
Appl Microbiol Biotechnol ; 102(6): 2867-2884, 2018 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-29392386

RESUMO

A dual-component Mu-transposition system was modified for the integration/amplification of genes in Corynebacterium. The system consists of two types of plasmids: (i) a non-replicative integrative plasmid that contains the transposing mini-Mu(LR) unit bracketed by the L/R Mu ends or the mini-Mu(LER) unit, which additionally contains the enhancer element, E, and (ii) an integration helper plasmid that expresses the transposition factor genes for MuA and MuB. Efficient transposition in the C. glutamicum chromosome (≈ 2 × 10-4 per cell) occurred mainly through the replicative pathway via cointegrate formation followed by possible resolution. Optimizing the E location in the mini-Mu unit significantly increased the efficiency of Mu-driven intramolecular transposition-amplification in C. glutamicum as well as in gram-negative bacteria. The new C. glutamicum genome modification strategy that was developed allows the consequent independent integration/amplification/fixation of target genes at high copy numbers. After integration/amplification of the first mini-Mu(LER) unit in the C. glutamicum chromosome, the E-element, which is bracketed by lox-like sites, is excised by Cre-mediated fashion, thereby fixing the truncated mini-Mu(LR) unit in its position for the subsequent integration/amplification of new mini-Mu(LER) units. This strategy was demonstrated using the genes for the citrine and green fluorescent proteins, yECitrine and yEGFP, respectively.


Assuntos
Bacteriófago mu , Cromossomos Bacterianos , Corynebacterium glutamicum/genética , Elementos de DNA Transponíveis , Edição de Genes/métodos , Genética Microbiana/métodos , Dosagem de Genes , Vetores Genéticos , Plasmídeos , Recombinação Genética
8.
PLoS Pathog ; 12(4): e1005600, 2016 04.
Artigo em Inglês | MEDLINE | ID: mdl-27128797

RESUMO

Type I (IFN-α/ß) and type III (IFN-λ) interferons (IFNs) exert shared antiviral activities through distinct receptors. However, their relative importance for antiviral protection of different organ systems against specific viruses remains to be fully explored. We used mouse strains deficient in type-specific IFN signaling, STAT1 and Rag2 to dissect distinct and overlapping contributions of type I and type III IFNs to protection against homologous murine (EW-RV strain) and heterologous (non-murine) simian (RRV strain) rotavirus infections in suckling mice. Experiments demonstrated that murine EW-RV is insensitive to the action of both types of IFNs, and that timely viral clearance depends upon adaptive immune responses. In contrast, both type I and type III IFNs can control replication of the heterologous simian RRV in the gastrointestinal (GI) tract, and they cooperate to limit extra-intestinal simian RRV replication. Surprisingly, intestinal epithelial cells were sensitive to both IFN types in neonatal mice, although their responsiveness to type I, but not type III IFNs, diminished in adult mice, revealing an unexpected age-dependent change in specific contribution of type I versus type III IFNs to antiviral defenses in the GI tract. Transcriptional analysis revealed that intestinal antiviral responses to RV are triggered through either type of IFN receptor, and are greatly diminished when receptors for both IFN types are lacking. These results also demonstrate a murine host-specific resistance to IFN-mediated antiviral effects by murine EW-RV, but the retention of host efficacy through the cooperative action by type I and type III IFNs in restricting heterologous simian RRV growth and systemic replication in suckling mice. Collectively, our findings revealed a well-orchestrated spatial and temporal tuning of innate antiviral responses in the intestinal tract where two types of IFNs through distinct patterns of their expression and distinct but overlapping sets of target cells coordinately regulate antiviral defenses against heterologous or homologous rotaviruses with substantially different effectiveness.


Assuntos
Interferon Tipo I/imunologia , Interferon gama/imunologia , Intestinos/imunologia , Infecções por Rotavirus/imunologia , Animais , Animais Recém-Nascidos , Modelos Animais de Doenças , Ensaio de Imunoadsorção Enzimática , Humanos , Immunoblotting , Imuno-Histoquímica , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Reação em Cadeia da Polimerase , Rotavirus
9.
Opt Express ; 23(21): 27606-11, 2015 Oct 19.
Artigo em Inglês | MEDLINE | ID: mdl-26480420

RESUMO

We study the radiation build-up in laminar and turbulent generation regimes in quasi-CW Raman fiber laser. We found the resulted spectral shape and generation type is defined by the total spectral broadening/narrowing balance over laser cavity round-trip, which is substantially different in different regimes starting from first round-trips of the radiation build-up. In turbulent regime, the steady-state is reached only after a few round-trips, while in the laminar regime the laser approaches the equilibrium spectrum shape asymptotically.

10.
Nat Prod Commun ; 10(3): 417-9, 2015 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-25924518

RESUMO

A flavonoid was isolated from the fronds of Asplenium ruta-muraria and A. altajense (Aspleniaceae) collected in the Altai Mountains and adjacent area. The compound was identified as kaempferol 3-O-ß-[(6'''-E-caffeoylglucopyranosyl)-(1-->3)-glucopyranoside]-7-O-ß-glucopyranoside (1) by UV, 1H and 13C NMR spectroscopy, LC-MS, and acid and alkaline hydrolyses. Another flavonoid (2) was isolated from A. altajense, as a minor compound, together with 1 and identified as deacylated compound 1, i.e. kaempferol 3-O-laminaribioside-7-O-glucoside. They were found in nature for the first time.


Assuntos
Quempferóis/química , Estrutura Molecular
11.
Cardiovasc Res ; 106(1): 121-30, 2015 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-25661082

RESUMO

AIMS: Sphingosylphosphorylcholine (SPC) elicits vasoconstriction at micromolar concentrations. At lower concentrations (≤1 µmol/L), however, it does not constrict intrapulmonary arteries (IPAs), but strongly potentiates vasoreactivity. Our aim was to determine whether this also occurs in a systemic artery and to delineate the signalling pathway. METHODS AND RESULTS: Rat mesenteric arteries and IPAs mounted on a myograph were challenged with ∼25 mmol/L [K+] to induce a small vasoconstriction. SPC (1 µmol/L) dramatically potentiated this constriction in all arteries by ∼400%. The potentiation was greatly suppressed or abolished by inhibition of phospholipase C (PLC; U73122), PKCε (inhibitory peptide), Src (PP2), and NADPH oxidase (VAS2870), and also by Tempol (superoxide scavenger), but not by inhibition of Rho kinase (Y27632). Potentiation was lost in mesenteric arteries from p47(phox-/-), but not NOX2(-/-), mice. The intracellular superoxide generator LY83583 mimicked the effect of SPC. SPC elevated reactive oxygen species (ROS) in vascular smooth muscle cells, and this was blocked by PP2, VAS2870, and siRNA knockdown of PKCε. SPC (1 µmol/L) significantly reduced the EC50 for U46619-induced vasoconstriction, an action ablated by Tempol. In patch-clamped mesenteric artery cells, SPC (200 nmol/L) enhanced Ba2+ current through L-type Ca2+ channels, an action abolished by Tempol but mimicked by LY83583. CONCLUSION: Our results suggest that low concentrations of SPC activate a PLC-coupled and NOX1-mediated increase in ROS, with consequent enhancement of voltage-gated Ca2+ entry and thus vasoreactivity. We speculate that this pathway is not specific for SPC, but may also contribute to vasoconstriction elicited by other G-protein coupled receptor and PLC-coupled agonists.


Assuntos
Canais de Cálcio/efeitos dos fármacos , Artérias Mesentéricas/fisiologia , NADH NADPH Oxirredutases/fisiologia , Fosforilcolina/análogos & derivados , Artéria Pulmonar/fisiologia , Espécies Reativas de Oxigênio/metabolismo , Esfingosina/análogos & derivados , Vasoconstrição/efeitos dos fármacos , Animais , Canais de Cálcio/fisiologia , Óxidos N-Cíclicos/farmacologia , Relação Dose-Resposta a Droga , Glicoproteínas de Membrana/deficiência , Glicoproteínas de Membrana/genética , Glicoproteínas de Membrana/fisiologia , Artérias Mesentéricas/efeitos dos fármacos , Camundongos , Camundongos Knockout , Modelos Animais , NADPH Oxidase 1 , NADPH Oxidase 2 , NADPH Oxidases/deficiência , NADPH Oxidases/genética , NADPH Oxidases/farmacologia , NADPH Oxidases/fisiologia , Fosforilcolina/farmacologia , Proteína Quinase C-épsilon/farmacologia , Artéria Pulmonar/efeitos dos fármacos , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/fisiologia , Esfingosina/farmacologia , Marcadores de Spin , Fosfolipases Tipo C/farmacologia , Vasoconstrição/fisiologia
12.
J Biol Chem ; 289(37): 25750-63, 2014 Sep 12.
Artigo em Inglês | MEDLINE | ID: mdl-25074926

RESUMO

TYRO3, AXL, and MER receptors (TAMs) are three homologous type I receptor-tyrosine kinases that are activated by endogenous ligands, protein S (PROS1) and growth arrest-specific gene 6 (GAS6). These ligands can either activate TAMs as soluble factors, or, in turn, opsonize phosphatidylserine (PS) on apoptotic cells (ACs) and serve as bridging molecules between ACs and TAMs. Abnormal expression and activation of TAMs have been implicated in promoting proliferation and survival of cancer cells, as well as in suppressing anti-tumor immunity. Despite the fact that TAM receptors share significant similarity, little is known about the specificity of interaction between TAM receptors and their ligands, particularly in the context of ACs, and about the functional diversity of TAM receptors. To study ligand-mediated activation of TAMs, we generated a series of reporter cell lines expressing chimeric TAM receptors. Using this system, we found that each TAM receptor has a unique pattern of interaction with and activation by GAS6 and PROS1, which is also differentially affected by the presence of ACs, PS-containing lipid vesicles and enveloped virus. We also demonstrated that γ-carboxylation of ligands is essential for the full activation of TAMs and that soluble immunoglobulin-like TAM domains act as specific ligand antagonists. These studies demonstrate that, despite their similarity, TYRO3, AXL, and MER are likely to perform distinct functions in both immunoregulation and the recognition and removal of ACs.


Assuntos
Apoptose/genética , Proteínas Proto-Oncogênicas/genética , Receptores Proteína Tirosina Quinases/genética , Proteínas Sanguíneas/metabolismo , Feminino , Regulação Neoplásica da Expressão Gênica , Humanos , Peptídeos e Proteínas de Sinalização Intercelular/metabolismo , Células Jurkat , Proteína S , Proteínas Proto-Oncogênicas/metabolismo , Receptores Proteína Tirosina Quinases/metabolismo , Transdução de Sinais , Estomatite Vesicular/genética , c-Mer Tirosina Quinase
13.
Opt Express ; 22(1): 1058-64, 2014 Jan 13.
Artigo em Inglês | MEDLINE | ID: mdl-24515065

RESUMO

For the first time we report the results of both numerical simulation and experimental observation of second-harmonic generation as an example of non-linear frequency conversion of pulses generated by passively mode-locked fiber master oscillator in different regimes including conventional (stable) and double-scale (partially coherent and noise-like) ones. We show that non-linear frequency conversion efficiency of double-scale pulses is slightly higher than that of conventional picosecond laser pulses with the same energy and duration despite strong phase fluctuations of double-scale pulses.

14.
Opt Express ; 21(18): 21236-41, 2013 Sep 09.
Artigo em Inglês | MEDLINE | ID: mdl-24103997

RESUMO

For the first time we report full numerical NLSE-based modeling of generation properties of random distributed feedback fiber laser based on Rayleigh scattering. The model which takes into account the random backscattering via its average strength only describes well power and spectral properties of random DFB fiber lasers. The influence of dispersion and nonlinearity on spectral and statistical properties is investigated. The evidence of non-gaussian intensity statistics is found.

15.
BMC Syst Biol ; 7: 56, 2013 Jul 05.
Artigo em Inglês | MEDLINE | ID: mdl-23826972

RESUMO

BACKGROUND: Celiac disease (CD) is an autoimmune disorder that occurs in genetically predisposed people and is caused by a reaction to the gluten protein found in wheat, which leads to intestinal villous atrophy. Currently there is no drug for treatment of CD. The only known treatment is lifelong gluten-free diet. The main aim of this work is to develop a mathematical model of the immune response in CD patients and to predict the efficacy of a transglutaminase-2 (TG-2) inhibitor as a potential drug for treatment of CD. RESULTS: A thorough analysis of the developed model provided the following results:1. TG-2 inhibitor treatment leads to insignificant decrease in antibody levels, and hence remains higher than in healthy individuals.2. TG-2 inhibitor treatment does not lead to any significant increase in villous area.3. The model predicts that the most effective treatment of CD would be the use of gluten peptide analogs that antagonize the binding of immunogenic gluten peptides to APC. The model predicts that the treatment of CD by such gluten peptide analogs can lead to a decrease in antibody levels to those of normal healthy people, and to a significant increase in villous area. CONCLUSIONS: The developed mathematical model of immune response in CD allows prediction of the efficacy of TG-2 inhibitors and other possible drugs for the treatment of CD: their influence on the intestinal villous area and on the antibody levels. The model also allows to understand what processes in the immune response have the strongest influence on the efficacy of different drugs. This model could be applied in the pharmaceutical R&D arena for the design of drugs against autoimmune small intestine disorders and on the design of their corresponding clinical trials.


Assuntos
Imunidade Adaptativa/efeitos dos fármacos , Doença Celíaca/tratamento farmacológico , Doença Celíaca/imunologia , Inibidores Enzimáticos/farmacologia , Imunidade Inata/efeitos dos fármacos , Modelos Imunológicos , Anticorpos/sangue , Anticorpos/imunologia , Células Apresentadoras de Antígenos/efeitos dos fármacos , Células Apresentadoras de Antígenos/imunologia , Doença Celíaca/sangue , Doença Celíaca/enzimologia , Inibidores Enzimáticos/uso terapêutico , Proteínas de Ligação ao GTP/antagonistas & inibidores , Proteínas de Ligação ao GTP/imunologia , Glutens/química , Humanos , Interleucina-15/imunologia , Intestino Delgado/imunologia , Fragmentos de Peptídeos/química , Fragmentos de Peptídeos/farmacologia , Reprodutibilidade dos Testes , Transglutaminases/antagonistas & inibidores , Transglutaminases/imunologia
16.
Microbiologyopen ; 2(3): 471-81, 2013 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-23554367

RESUMO

A unique operon structure has been identified in the genomes of several plant- and insect-associated bacteria. The distinguishing feature of this operon is the presence of tandem hilA and hilB genes encoding dioxygenases belonging to the PF13640 and PF10014 (BsmA) Pfam families, respectively. The genes encoding HilA and HilB from Pantoea ananatis AJ13355 were cloned and expressed in Escherichia coli. The culturing of E. coli cells expressing hilA (E. coli-HilA) or both hilA and hilB (E. coli-HilAB) in the presence of l-isoleucine resulted in the conversion of l-isoleucine into two novel biogenic compounds: l-4'-isoleucine and l-4,4'-dihydroxyisoleucine, respectively. In parallel, two novel enzymatic activities were detected in the crude cell lysates of the E. coli-HilA and E. coli-HilAB strains: l-isoleucine, 2-oxoglutarate: oxygen oxidoreductase (4'-hydroxylating) (HilA) and l-4'-hydroxyisoleucine, 2-oxoglutarate: oxygen oxidoreductase (4-hydroxylating) (HilB), respectively. Two hypotheses regarding the physiological significance of C-4(4')-hydroxylation of l-isoleucine in bacteria are also discussed. According to first hypothesis, the l-isoleucine dihydroxylation cascade is involved in synthesis of dipeptide antibiotic in P. ananatis. Another unifying hypothesis is that the C-4(4')-hydroxylation of l-isoleucine in bacteria could result in the synthesis of signal molecules belonging to two classes: 2(5H)-furanones and analogs of N-acyl homoserine lactone.


Assuntos
Dioxigenases/genética , Dioxigenases/metabolismo , Isoleucina/metabolismo , Redes e Vias Metabólicas/genética , Pantoea/enzimologia , Pantoea/metabolismo , Biotransformação , Clonagem Molecular , Escherichia coli/genética , Expressão Gênica
17.
Cardiovasc Res ; 97(2): 293-301, 2013 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-23042470

RESUMO

AIMS: Based on indirect methods, it has been suggested that both L- and T-type Ca(2+) channels mediate signalling in the renal afferent arteriole and that T-type Ca(2+) channels are involved in signalling in the efferent arteriole. However, Ca(2+) currents have never been studied in these two vessels. Our study was initiated to directly determine the type of Ca(2+) channels in these vessels for the first time, using patch clamp. METHODS AND RESULTS: Native myocytes were obtained from individually isolated rat renal afferent and efferent arterioles and from rat tail arteries (TA). TA myocytes, which possess both L- and T-type Ca(2+) currents, served as a positive control. Inward Ca(2+) and Ba(2+) currents (I(Ca) and I(Ba)) were measured in 1.5 mmol/L Ca(2+) and 10 mmol/L Ba(2+), respectively, using the whole-cell configuration. By exploiting known differences in activation and inactivation characteristics and differing sensitivities to nifedipine and kurtoxin, the presence of both L- and T-type Ca(2+) channels in TA myocytes was readily demonstrated. Afferent arteriolar myocytes exhibited relatively large I(Ca) densities (-2.0 ± 0.2 pA/pF) in physiological Ca(2+) and the I(Ba) was 3.6-fold greater. These currents were blocked by nifedipine, but not by kurtoxin, and did not exhibit the activation and inactivation characteristics of T-type Ca(2+) channels. Efferent arteriolar myocytes did not exhibit a discernible voltage-activated I(Ca) in physiological Ca(2+). CONCLUSION: Our findings support the physiological role of L-type Ca(2+) channels in the afferent, but not efferent, arteriole, but do not support the premise that functional T-type Ca(2+) channels are present in either vessel.


Assuntos
Arteríolas/metabolismo , Canais de Cálcio Tipo L/fisiologia , Canais de Cálcio Tipo T/fisiologia , Rim/irrigação sanguínea , Músculo Liso Vascular/metabolismo , Animais , Masculino , Músculo Liso Vascular/citologia , Nifedipino/farmacologia , Técnicas de Patch-Clamp , Ratos , Ratos Sprague-Dawley , Venenos de Escorpião/farmacologia
18.
Appl Microbiol Biotechnol ; 97(6): 2467-72, 2013 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-22584432

RESUMO

L-Leucine 5-hydroxylase (LdoA) previously found in Nostoc punctiforme PCC 73102 is a novel type of Fe(II)/α-ketoglutarate-dependent dioxygenase. LdoA catalyzed regio- and stereoselective hydroxylation of L-leucine and L-norleucine into (2S,4S)-5-hydroxyleucine and (2S)-5-hydroxynorleucine, respectively. Moreover, LdoA catalyzed sulfoxidation of L-methionine and L-ethionine in the same manner as previously described L-isoleucine 4-hydroxylase. Therefore LdoA should be a promising biocatalyst for effective production of industrially useful amino acids.


Assuntos
Dioxigenases/isolamento & purificação , Dioxigenases/metabolismo , Ferro/metabolismo , Ácidos Cetoglutáricos/metabolismo , Leucina/análogos & derivados , Leucina/metabolismo , Nostoc/enzimologia , Etionina/metabolismo , Metionina/metabolismo , Norleucina/metabolismo , Safrol/análogos & derivados , Safrol/metabolismo
19.
FEMS Microbiol Lett ; 331(2): 97-104, 2012 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-22448874

RESUMO

L-isoleucine-4-hydroxylase (IDO) is a recently discovered member of the Pfam family PF10014 (the former DUF 2257 family) of uncharacterized conserved bacterial proteins. To uncover the range of biochemical activities carried out by PF10014 members, eight in silico-selected IDO homologues belonging to the PF10014 were cloned and expressed in Escherichia coli. L-methionine, L-leucine, L-isoleucine and L-threonine were found to be catalysed by the investigated enzymes, producing L-methionine sulfoxide, 4-hydroxyleucine, 4-hydroxyisoleucine and 4-hydroxythreonine, respectively. An investigation of enzyme kinetics suggested the existence of a novel subfamily of bacterial dioxygenases within the PF10014 family for which free L-amino acids could be accepted as in vivo substrates. A hypothesis regarding the physiological significance of hydroxylated l-amino acids is also discussed.


Assuntos
Aminoácidos/metabolismo , Bactérias/enzimologia , Dioxigenases/metabolismo , Escherichia coli/enzimologia , Bactérias/classificação , Bactérias/genética , Clonagem Molecular , Dioxigenases/classificação , Dioxigenases/genética , Escherichia coli/genética , Hidroxilação , Isoleucina/metabolismo , Cinética , Leucina/metabolismo , Metionina/metabolismo , Especificidade por Substrato , Treonina/metabolismo
20.
Analyst ; 137(7): 1604-10, 2012 Apr 07.
Artigo em Inglês | MEDLINE | ID: mdl-22337290

RESUMO

Modern analytical chemistry of industrial products is in need of rapid, robust, and cheap analytical methods to continuously monitor product quality parameters. For this reason, spectroscopic methods are often used to control the quality of industrial products in an on-line/in-line regime. Vibrational spectroscopy, including mid-infrared (MIR), Raman, and near-infrared (NIR), is one of the best ways to obtain information about the chemical structures and the quality coefficients of multicomponent mixtures. Together with chemometric algorithms and multivariate data analysis (MDA) methods, which were especially created for the analysis of complicated, noisy, and overlapping signals, NIR spectroscopy shows great results in terms of its accuracy, including classical prediction error, RMSEP. However, it is unclear whether the combined NIR + MDA methods are capable of dealing with much more complex interpolation or extrapolation problems that are inevitably present in real-world applications. In the current study, we try to make a rather general comparison of linear, such as partial least squares or projection to latent structures (PLS); "quasi-nonlinear", such as the polynomial version of PLS (Poly-PLS); and intrinsically non-linear, such as artificial neural networks (ANNs), support vector regression (SVR), and least-squares support vector machines (LS-SVM/LSSVM), regression methods in terms of their robustness. As a measure of robustness, we will try to estimate their accuracy when solving interpolation and extrapolation problems. Petroleum and biofuel (biodiesel) systems were chosen as representative examples of real-world samples. Six very different chemical systems that differed in complexity, composition, structure, and properties were studied; these systems were gasoline, ethanol-gasoline biofuel, diesel fuel, aromatic solutions of petroleum macromolecules, petroleum resins in benzene, and biodiesel. Eighteen different sample sets were used in total. General conclusions are made about the applicability of ANN- and SVM-based regression tools in the modern analytical chemistry. The effectiveness of different multivariate algorithms is different when going from classical accuracy to robustness. Neural networks, which are capable of producing very accurate results with respect to classical RMSEP, are not able to solve interpolation problems or, especially, extrapolation problems. The chemometric methods that are based on the support vector machine (SVM) ideology are capable of solving both classical regression and interpolation/extrapolation tasks.


Assuntos
Técnicas de Química Analítica , Análise Multivariada , Espectroscopia de Luz Próxima ao Infravermelho , Biocombustíveis/análise , Gasolina/análise
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...