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1.
Br Poult Sci ; : 1-9, 2024 May 08.
Artigo em Inglês | MEDLINE | ID: mdl-38717314

RESUMO

1. Epidemiological surveillance of Salmonella spp. serves as a primary tool for maintaining the health of poultry flocks. Characterising circulating serotypes is crucial for implementing control and prevention measures. This study conducted phenotypic and molecular characterisation of S. enterica Pullorum, S. enterica Heidelberg, and S. enterica Corvalis isolated from broiler chickens during slaughtering.2. All strains were susceptible to gentamicin, neomycin and norfloxacin. However, resistance rates exceeded 50% for ciprofloxacin and tiamulin, irrespective of the serotype. Approximately 64% of strains were classified as multidrug-resistant, with S. enterica Heidelberg strains exhibiting significantly higher overall resistance. The isolates demonstrated the ability to adhere and produce biofilm at a minimum of three temperatures, with S. enterica Pullorum capable of biofilm production at all temperatures encountered during poultry rearing.3. Each strain possessed between two and seven different virulence-associated genes. Genetic similarity, as indicated by pulsed field gel electrophoresis, exceeded 90% for all three serotypes and strains were classified in the R5 ribotype by PCR, regardless of serotype. Sequencing revealed high similarity among all strains, with homology ranging from 99.61 to 100% and all were classified to a single cluster.4. The results suggested a clonal relationship among the strains, indicating the possible circulation of a unique clonal group of S. enterica Pullorum in the southern region of Brazil.

2.
medRxiv ; 2024 May 03.
Artigo em Inglês | MEDLINE | ID: mdl-38746357

RESUMO

Importance: Understanding antidepressant mechanisms could help design more effective and tolerated treatments. Objective: Identify DNA methylation (DNAm) changes associated with antidepressant exposure. Design: Case-control methylome-wide association studies (MWAS) of antidepressant exposure were performed from blood samples collected between 2006-2011 in Generation Scotland (GS). The summary statistics were tested for enrichment in specific tissues, gene ontologies and an independent MWAS in the Netherlands Study of Depression and Anxiety (NESDA). A methylation profile score (MPS) was derived and tested for its association with antidepressant exposure in eight independent cohorts, alongside prospective data from GS. Setting: Cohorts; GS, NESDA, FTC, SHIP-Trend, FOR2107, LBC1936, MARS-UniDep, ALSPAC, E-Risk, and NTR. Participants: Participants with DNAm data and self-report/prescription derived antidepressant exposure. Main Outcomes and Measures: Whole-blood DNAm levels were assayed by the EPIC/450K Illumina array (9 studies, N exposed = 661, N unexposed = 9,575) alongside MBD-Seq in NESDA (N exposed = 398, N unexposed = 414). Antidepressant exposure was measured by self- report and/or antidepressant prescriptions. Results: The self-report MWAS (N = 16,536, N exposed = 1,508, mean age = 48, 59% female) and the prescription-derived MWAS (N = 7,951, N exposed = 861, mean age = 47, 59% female), found hypermethylation at seven and four DNAm sites (p < 9.42x10 -8 ), respectively. The top locus was cg26277237 ( KANK1, p self-report = 9.3x10 -13 , p prescription = 6.1x10 -3 ). The self-report MWAS found a differentially methylated region, mapping to DGUOK-AS1 ( p adj = 5.0x10 -3 ) alongside significant enrichment for genes expressed in the amygdala, the "synaptic vesicle membrane" gene ontology and the top 1% of CpGs from the NESDA MWAS (OR = 1.39, p < 0.042). The MPS was associated with antidepressant exposure in meta-analysed data from external cohorts (N studies = 9, N = 10,236, N exposed = 661, f3 = 0.196, p < 1x10 -4 ). Conclusions and Relevance: Antidepressant exposure is associated with changes in DNAm across different cohorts. Further investigation into these changes could inform on new targets for antidepressant treatments. 3 Key Points: Question: Is antidepressant exposure associated with differential whole blood DNA methylation?Findings: In this methylome-wide association study of 16,536 adults across Scotland, antidepressant exposure was significantly associated with hypermethylation at CpGs mapping to KANK1 and DGUOK-AS1. A methylation profile score trained on this sample was significantly associated with antidepressant exposure (pooled f3 [95%CI]=0.196 [0.105, 0.288], p < 1x10 -4 ) in a meta-analysis of external datasets. Meaning: Antidepressant exposure is associated with hypermethylation at KANK1 and DGUOK-AS1 , which have roles in mitochondrial metabolism and neurite outgrowth. If replicated in future studies, targeting these genes could inform the design of more effective and better tolerated treatments for depression.

3.
Br Poult Sci ; 61(6): 640-645, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32901508

RESUMO

1. Salmonella Gallinarum (SG) infections cause fowl typhoid, which leads to important economic losses. Multidrug resistance (MDR) and the capacity for bacteria to form biofilms could play an important role in the persistence of SG in poultry flocks resulting in intermittent disease outbreaks. The aim of the following study was to assess the lytic activity of two new bacteriophages (Salmonella phages UPF_BP1 and UPF_BP2) against MDR and biofilm-forming SG. 2. Forty-six strains of SG, isolated in 2015, were characterised by antimicrobial resistance, biofilm formation profiles and susceptibility to two new bacteriophages. 3. Of these strains, 24% were multidrug resistant and more than 80% formed biofilm, with no statistical difference between incubation temperatures (42°C or 22°C). With regard to the lytic activity of the phages, 85% of strains were susceptible to at least one phage. Of these, 74% were lysed by both phages, including MDR and biofilm producing strains. 4. The use of salmonella phages UPF_BP1 and UPF_BP2 were shown to be promising alternatives for the biological control of fowl typhoid.


Assuntos
Bacteriófagos , Doenças das Aves Domésticas , Salmonelose Animal , Salmonella enterica , Animais , Biofilmes , Galinhas , Aves Domésticas
4.
Am J Transplant ; 18(6): 1481-1488, 2018 06.
Artigo em Inglês | MEDLINE | ID: mdl-29286569

RESUMO

The incidence of acute kidney injury (AKI) and its impact on chronic kidney disease (CKD) following pediatric nonkidney solid organ transplantation is unknown. We aimed to determine the incidence of AKI and CKD and examine their relationship among children who received a heart, lung, liver, or multiorgan transplant at the Hospital for Sick Children between 2002 and 2011. AKI was assessed in the first year posttransplant. Among 303 children, perioperative AKI (within the first week) occurred in 67% of children, and AKI after the first week occurred in 36%, with the highest incidence among lung and multiorgan recipients. Twenty-three children (8%) developed CKD after a median follow-up of 3.4 years. Less than 5 children developed end-stage renal disease, all within 65 days posttransplant. Those with 1 AKI episode by 3 months posttransplant had significantly greater risk for developing CKD after adjusting for age, sex, and estimated glomerular filtration rate at transplant (hazard ratio: 2.77, 95% confidence interval, 1.13-6.80, P trend = .008). AKI is common in the first year posttransplant and associated with significantly greater risk of developing CKD. Close monitoring for kidney disease may allow for earlier implementation of kidney-sparing strategies to decrease risk for progression to CKD.


Assuntos
Injúria Renal Aguda/etiologia , Transplante de Órgãos/efeitos adversos , Criança , Pré-Escolar , Estudos de Coortes , Creatinina/sangue , Feminino , Taxa de Filtração Glomerular , Humanos , Masculino , Doadores de Tecidos
5.
Arq. bras. med. vet. zootec. (Online) ; 70(6): 1855-1861, nov.-dez. 2018. tab
Artigo em Inglês | LILACS, VETINDEX | ID: biblio-970582

RESUMO

Fowl Cholera (FC) is a disease caused by Pasteurella multocida. The severity of this disease is partly caused by virulence factors. Genes encoding fimbriae, capsule, sialidases and proteins for iron metabolism may be related to P. multocida's ability to infect the host. Besides to examining DNA for the presence of virulence genes, DNA is essential for the diagnostic and FTA cards are an alternative for genetic material transport. The study aims to evaluate the viability of P. multocida DNA transport using the cards and to detect 14 virulence genes in 27 strains isolated from FC cases in the United States by multiplex-PCR. No growth was observed in any of the FTA cards, which was essential to assess the security. Furthermore, DNA detection was possible in 100% of the samples, independent of the storage period (7 to 35 days) and temperature (4°C and 37°C). ptfA, exbd-tonB, hgbA, nanB, oma87, hyaD-hyaC, sodC, hgbB, sodA, nanH and pfhA genes were detected in more than 80% of the samples. FTA cards have proven to be a viable and safe tool for DNA transport of P. multocida. A majority of genes showed a high frequency, which was similar to strains isolated from FC cases.(AU)


Cólera aviária (CA) é uma doença causada pela bactéria Pasteurella multocida e a severidade dos casos é em parte justificada por fatores de virulência. Genes codificando fímbrias, cápsulas, sialidases, dismutases e proteínas do metabolismo férrico podem ser relacionados à capacidade do agente em infectar o hospedeiro. Além da obtenção do DNA para pesquisa de genes de virulência, o material genético é fundamental para o diagnóstico, e os cartões FTA seriam uma alternativa no transporte de microrganismos. Os objetivos da presente pesquisa foram avaliar a viabilidade do transporte de DNA de P. multocida através dos cartões e detectar 14 genes de virulência em 27 cepas isoladas de CA nos Estados Unidos, por meio de multiplex-PCR. Nenhuma das amostras para análise microbiológica da segurança dos cartões apresentou crescimento. Foi possível a detecção do DNA em 100% das amostras, independentemente do tempo de estocagem (sete a 35 dias) e das temperaturas (4°C e 37°C) avaliadas. Genes ptfA, exbd-tonB, hgbA, nanB, oma87, hyaD-hyaC, sodC, hgbB, sodA, nanH e pfhA foram detectados em mais de 80% das amostras. Os cartões FTA demonstraram ser uma ferramenta viável e segura para o transporte do DNA de P. multocida. A maioria dos genes apresentou uma alta frequência, compatível com isolados de CA.(AU)


Assuntos
Pasteurella multocida/genética , Pasteurella multocida/patogenicidade , Fatores de Virulência/isolamento & purificação
6.
Arq. bras. med. vet. zootec ; 68(2): 257-264, mar.-abr. 2016. tab, graf
Artigo em Inglês | LILACS | ID: lil-779790

RESUMO

Salmonella Enteritidis and Salmonella Typhimurium are responsible for causing huge economic loses in aviculture, as they lead young broiler chicks to develop clinical disease and thus increase mortality. Salmonella's pathogenicity is considered complex and multifactorial, demanding more studies that could elucidate the interaction between host and pathogen. The present study aims to evaluate the virulence of 130S. Enteritidis isolates and 70S. Typhimurium inoculated in one-day-old chicks through the establishment of a pathogenicity index. For each strain, 10 commercial chicks from the Cobb lineage were used. Then, 200µL of a solution containing 2x108 CFU of S. Enteritidis or S. Typhimurium were inoculated in the birds by intraperitoneal via. Mortality and presence of lesions such as aerosaculitis (A), perihepatitis (Ph), pericarditis (Pc), peritonitis (Pt), onfalitis (O) and cellulitis (C) were registered daily for seven days. From the second to the seventh day there was a proportional decrease in the punctuation of the time of death (TD) for each day that the bird had survived. The pathogenicity index was calculated using the following formula: PI = (TD x 5) + A + Ph + Pc + Pt + O + C. The obtainment of the PI of each bacterial sample was achieved by calculating the rate of the ten inoculated birds. Based on the obtained results, it was possible to attribute the pathogenicity value for each strain, which enabled us to classify them in groups of low (27/200), intermediate (95/200) and high (78/200) pathogenicity. The utilization of standards like time of death and presence of septicemic lesions made it possible to determine the pathogenicity rate for each strain. Besides that, the proposed model has presented dramatic differences between the high, intermediate and low pathogenicity groups, which makes this mechanism useful for further classification of strains isolated in poultry farms.


Salmonella Enteritidis e Salmonella Typhimurium são responsáveis por imensos prejuízos econômicos ao setor avícola, podendo levar ao desenvolvimento de doença clínica e ao aumento da mortalidade em aves jovens. A patogenicidade de Salmonella é considerada complexa e multifatorial, necessitando de estudos que possam esclarecer a interação entre patógeno e hospedeiro. O presente trabalho teve por objetivo avaliar a virulência de 130 isolados de S. Enteritidis e 70 de S.Typhimurium, inoculadas em pintos de um dia de idade, por meio do estabelecimento de um índice de patogenicidade. Para cada cepa, foram utilizados 10 pintos comerciais da linhagem Cobb. As aves foram inoculadas com 200µL de uma solução contendo 2x108 UFC de S. Enteritidis ou S. Typhimurium, por via intraperitoneal. A mortalidade e a presença de lesões como aerossaculite (A), peri-hepatite (Ph), pericardite (Pc), peritonite (Pt), onfalite (O) e celulite (C) foram registradas diariamente durante sete dias. Do segundo ao sétimo dia, houve uma diminuição proporcional da pontuação no tempo de morte (TM) a cada dia em que o animal sobrevivia. O cálculo do índice de patogenicidade de cada pintinho inoculado (IP) obedeceu à seguinte fórmula: IP = (TMx5) + A + Ph + Pc + Pt + O + C. Para obtenção do IP de cada amostra, foi realizada a média do IP obtido com as 10 aves inoculadas. Com base nos resultados observados, foi possível atribuir um valor de patogenicidade a cada uma das cepas, permitindo classificá-las em grupos de baixa (27/200), intermediária (95/200) e alta patogenicidade (78/200). A utilização de critérios, como tempo de morte e presença de lesões septicêmicas, permitiu a determinação de um índice de patogenicidade para cada cepa. Além disso, o modelo proposto apresentou diferença significativa entre os grupos de alta, intermediária e baixa patogenicidade, permitindo, assim, a sua aplicação para classificação futura das cepas isoladas em granjas avícolas.


Assuntos
Animais , Aves Domésticas , Salmonella enteritidis/patogenicidade , Salmonella typhimurium/patogenicidade , Salmonelose Animal/patologia , Interações Hospedeiro-Patógeno , Fatores de Virulência
7.
Arq. bras. med. vet. zootec ; 64(2): 286-294, abr. 2012. tab
Artigo em Português | LILACS | ID: lil-622479

RESUMO

Os eventos isquêmicos em cães são incomuns, porém podem estar sendo subnotificados. Avaliou-se o infarto agudo do miocárdio (IAM) clinicamente, por meio de eletrocardiografia (ECG), eletrocardiografia contínua (EC), ecocardiografia (ECO), enzima creatina quinase (CK), enzima creatina quinase fração MB (CK-MB) e anátomo-histologicamente em cães sem raça definida, e observou-se a ocorrência de arritmias após injeção intramiocárdia por EC. O IAM foi obtido após a ligadura da coronária descendente anterior. Os animais apresentaram ao ECO dilatação da câmara esquerda e aumento do índice de desempenho miocárdico. Ao ECG houve desnivelamento de ST nas derivações pré-cordiais V1 e V2. No EC observaram-se arritmias ventriculares graves e supradesnivelamento de ST. As enzimas CK e CK-MB aumentaram significativamente, sendo que os picos de CK-MB e de CK ocorreram seis horas e 12 horas, respectivamente, após o IAM. Na análise histológica constatou-se infarto da parede inferior do ventrículo esquerdo e substituição do tecido muscular por tecido fibroso. Avaliou-se a injeção intramiocárdica por EC que pode servir como via terapêutica cardíaca, não sendo observado aumento das arritmias ventriculares após a injeção no miocárdio infartado. O infarto em cães pode ser detectado pelos exames cardíacos disponíveis, e a injeção intramiocárdica é uma via terapêutica cardíaca possível.


Ischemic events in dogs are uncommon; however, this may be under-reported. The myocardial infarction was created by left anterior descending coronary ligation in healthy mongrel dogs in clinical and laboratorial exams. These dogs were evaluated clinically, electrocardiography (ECG), through ambulatory electrocardiography (AE), echocardiography (ECO), creatine kinase enzyme (CK), creatine kinase MB fraction enzyme (CK-MB) and histopathologically. Even in these animals we observed the occurrence of arrhythmia after intramyocardial injection by AE. The animals exhibited left ventricular chamber enlargement and increase in myocardial performance index at ECO. In ECG, there were deviations in ST segment in the precordial leads V1 and V2. CK and CK-MB showed high increase, CK and CK-MB peaks occurred six and 12 hours after infarction, respectively. Histopathology of the infarction in the inferior wall of the left ventricle and replacement of muscle tissue by fibrous tissue were seen. Furthermore, intramyocardial injection that may be used for therapeutic purposes was evaluated by AE, which demonstrated no increase in the ventricular arrhythmias. Therefore, myocardial infarction in dogs can be detected with the tests available and intramyocardial injection can be used as a therapeutic way.

9.
Arq. bras. med. vet. zootec ; 58(2): 184-189, abr. 2006. tab
Artigo em Português | LILACS | ID: lil-432669

RESUMO

Avaliaram-se os aspectos clínicos do entrópio de desenvolvimento em filhotes de cães da raça Shar Pei. Utilizaram-se 50 animais com idades entre 18 e 128 dias, que apresentavam graus variáveis de inversão palpebral e lesões oculares, as quais foram classificadas de acordo com um modelo específico proposto. As lesões encontradas foram fotofobia, epífora, inversão da margem palpebral, blefarospasmo, conjuntivite, quemose, edema, erosão e vascularização da córnea e phthisis bulbi.


Assuntos
Animais , Cães , Entrópio/diagnóstico , Entrópio/prevenção & controle , Entrópio/veterinária
12.
J Biol Chem ; 276(28): 25929-38, 2001 Jul 13.
Artigo em Inglês | MEDLINE | ID: mdl-11340067

RESUMO

The GluR1 glutamate receptor subunit is expressed in most brain areas and plays a major role in excitatory synaptic transmission. We cloned and sequenced 5 kilobase pairs of the rat GluR1 promoter and identified multiple transcriptional start sites between -295 and -202 (relative to the first ATG). Similar to other glutamate receptor subunit promoters, the GluR1 promoter lacks TATA and CAAT elements in that region but binds Sp1 proteins at two sites. Promoter activity of GluR1 fragments cloned into pGL3 was assessed by immunocytochemistry and by measuring luciferase activity after transfection into primary cultures of rat cortical neurons and glia. GluR1 promoter activity was stronger in neurons, with neuronal specificity appearing to reside mainly within the neuronal expression-enhancing regions, -1395 to -743 and -253 to -48. The latter region contains 4 sites that bound recombinant cAMP-response element-binding proteins and a glial silencing region between -253 and -202. In both neurons and glia, promoter activity was increased by a 64-base pair GA repeat upstream of the initiation sites and reduced by a 57-base pair region that contained an N box. In contrast to the GluR2 promoter the regulatory regions are mainly located outside of the GluR1 initiation region.


Assuntos
Receptores de AMPA/genética , Animais , Sequência de Bases , Clonagem Molecular , Dados de Sequência Molecular , Regiões Promotoras Genéticas/genética , Ratos , Ratos Wistar , Análise de Sequência de DNA
14.
FEMS Microbiol Lett ; 195(1): 79-83, 2001 Feb 05.
Artigo em Inglês | MEDLINE | ID: mdl-11166999

RESUMO

We have previously shown that beta-galactosidase activity expressed in Thermotoga neapolitana cells grown on lactose is subject to repression by glucose when they are grown on both substrates whereas beta-galactosidase and beta-glucosidase activities observed in cells grown on cellobiose are not repressed by growth on both glucose and cellobiose. To examine the differential expression of bgalA, bgalB, bglA and bglB in T. neapolitana, total RNA was isolated from cells growing on either glucose, lactose or cellobiose as the sole source of carbon and transcripts encoding these genes were quantitated by Northern blot analyses. BglA expression was induced by cellobiose while bglB was expressed under all three conditions at a lower level. Expression of the beta-galactosidase genes, bgalA and bgalB, was detected only in lactose-grown cells. beta-Glucosidase enzyme activity was only found in cell extracts of cellobiose-grown cells while beta-galactosidase activity was found in both lactose- and cellobiose-grown cell extracts. Our results show that in cellobiose-grown cells, the high beta-glucosidase activity is likely due to expression of bglA and that neither bgalA nor bgalB is responsible for the beta-galactosidase activity.


Assuntos
Bactérias Anaeróbias Gram-Negativas/crescimento & desenvolvimento , Bactérias Anaeróbias Gram-Negativas/genética , Northern Blotting , Celobiose/metabolismo , Meios de Cultura , Regulação Bacteriana da Expressão Gênica/genética , Glucose/metabolismo , Lactose/metabolismo , beta-Galactosidase/genética , beta-Galactosidase/metabolismo , beta-Glucosidase/genética , beta-Glucosidase/metabolismo
15.
Arch Microbiol ; 172(2): 95-101, 1999 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-10415170

RESUMO

An extremely thermophilic, sulfur-dependent archaeon, strain WT1, was isolated from a freshwater hot spring in the Lake Taupo area of North Island, New Zealand. The cells are flagellated, strictly anaerobic cocci that grow optimally at 85 degrees C and 5.4 g NaCl l(-1). The strain grows heterotrophically on complex proteinaceous substrates or on appropriate salts plus amino acid mixtures and is also able to utilize maltose, starch, and pyruvate. Elemental sulfur could be replaced by cystine or thioglycollate. The range of temperatures allowing growth is from 60 to 90 degrees C; the pH supporting growth ranges from 5 to 8 (optimum, pH 7). Strain WT1 grew in a defined medium containing amino acids as the sole carbon and energy sources. The required amino acids were: Arg, His, Ile, Leu, Phe, Ser, Thr, Trp, Tyr, and Val. Strain WT1 showed sensitivity to rifampicin. DNA G+C content was 50.4 mol%. Phylogenetic analysis of the sequence encoding the 16S rRNA gene indicated that this isolate is a member of the Thermococcales. DNA/DNA hybridization studies revealed no similarity to several species of Thermococcus and Pyrococcus, with the exception of Thermococcus zilligii. Based on the reported results, we propose strain WT1 as a new species to be named Thermococcus waiotapuensis sp. nov.


Assuntos
Thermococcus/isolamento & purificação , Microbiologia da Água , Técnicas de Tipagem Bacteriana , DNA Bacteriano/genética , DNA Ribossômico/genética , Temperatura Alta , Dados de Sequência Molecular , Filogenia , RNA Ribossômico 16S/genética , Thermococcus/classificação , Thermococcus/genética , Thermococcus/ultraestrutura
16.
Annu Rev Pharmacol Toxicol ; 39: 221-41, 1999.
Artigo em Inglês | MEDLINE | ID: mdl-10331083

RESUMO

Transcriptional and translational regulation of glutamate receptor expression determines one of the key phenotypic features of neurons in the brain--the properties of their excitatory synaptic receptors. Up- and down-regulation of various glutamate receptor subunits occur throughout development, following ischemia, seizures, repetitive activation of afferents, or chronic administration of a variety of drugs. The promoters of the genes that encode the NR1, NR2B, NR2C, GluR1, GluR2, and KA2 subunits share several characteristics that include multiple transcriptional start sites within a CpG island, lack of TATA and CAAT boxes, and neuronal-selective expression. In most cases, the promoter regions include overlapping Sp1 and GSG motifs near the major initiation sites, and a silencer element, to guide expression in neurons. Manipulating the levels of glutamate receptors in vivo by generating transgenic and knockout mice has enhanced understanding of the role of specific glutamate receptor subunits in long-term potentiation and depression, learning, seizures, neural pattern formation, and survival. Neuron-specific glutamate receptor promoter fragments may be employed in the design of novel gene-targeting constructs to deliver future experimental transgene and therapeutic agents to selected neurons in the brain.


Assuntos
Regulação da Expressão Gênica , Canais Iônicos/genética , Receptores de Glutamato/genética , Animais , Humanos , Canais Iônicos/biossíntese , Camundongos , Camundongos Knockout , Camundongos Transgênicos , Biossíntese de Proteínas , Receptores de Glutamato/biossíntese , Transcrição Gênica
19.
J Bacteriol ; 179(5): 1721-6, 1997 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-9045834

RESUMO

The reverse gyrase gene rgy from the hyperthermophilic archaeon Pyrococcus furiosus was cloned and sequenced. The gene is 3,642 bp (1,214 amino acids) in length. The deduced amino acid sequence has relatively high similarity to the sequences of the Methanococcus jannaschii reverse gyrase (48% overall identity), the Sulfolobus acidocaldarius reverse gyrase (41% identity), and the Methanopynrus kandleri reverse gyrase (37% identity). The P. furiosus reverse gyrase is a monomeric protein, containing a helicase-like module and a type I topoisomerase module, which resembles the enzyme from S. acidocaldarius more than that from M. kandleri, a heterodimeric protein encoded by two separate genes. The control region of the P. furiosus rgy gene contains a typical archaeal putative box A promoter element which is located at position -26 from the transcription start identified by primer extension experiments. The initiating ATG codon is preceded by a possible prokaryote-type ribosome-binding site. Purified P. furiosus reverse gyrase has a sedimentation coefficient of 6S, suggesting a monomeric structure for the native protein. The enzyme is a single polypeptide with an apparent molecular mass of 120 kDa, in agreement with the gene structure. The sequence of the N terminus of the protein corresponded to the deduced amino acid sequence. Phylogenetic analysis indicates that all known reverse gyrase topoisomerase modules form a subgroup inside subfamily IA of type I DNA topoisomerases (sensu Wang [J. C. Wang, Annu. Rev. Biochem. 65:635-692, 1996]). Our results suggest that the fusion between the topoisomerase and helicase modules of reverse gyrase occurred before the divergence of the two archaeal phyla, Crenoarchaeota and Euryarchaeota.


Assuntos
Archaea/enzimologia , DNA Topoisomerases Tipo II/química , DNA Topoisomerases Tipo II/genética , DNA Topoisomerases Tipo I , Sequência de Aminoácidos , Archaea/genética , Sequência de Bases , Clonagem Molecular , DNA Helicases/genética , DNA Topoisomerases Tipo II/metabolismo , Evolução Molecular , Genes Bacterianos , Dados de Sequência Molecular , Peso Molecular , Filogenia , Regiões Promotoras Genéticas , Conformação Proteica
20.
J Neurosci Res ; 42(4): 579-93, 1995 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-8568944

RESUMO

AMPA/kainate receptor activation in cultured oligodendrocyte precursor cells from embryonic mouse cortex leads to a blockade of delayed rectifying K+ currents. In the present study, we provide evidence using the patch-clamp technique in the whole-cell configuration that the mechanism linking kainate receptor activation and K+ conductance blockade is due to the receptor-mediated Na+ entry: 1) The blockade was not observed in Na(+)-free bathing solution nor when intracellular [Na+] was elevated by dialzying the cell with a pipette solution containing high [Na+]. 2) Elevation of intracellular [Na+] alone led to a blockade of outward currents in contrast to cells dialyzed by sucrose. High [Li+]i also reduced the outward currents, and in Li(+)-containing bathing solution the kainate-induced blockade of K+ channels was more pronounced. Probably, Li+ accumulates intracellularly after permeation through the receptor pore due to slower extrusion mechanisms. Experiments with GTP gamma S or GDP beta S and pertussis toxin indicated that GTP-binding protein-mediated mechanisms were not of importance for the kainate-induced K+ conductance blockade. Our data suggest that in glial precursor cells AMPA/kainate receptor activation leads to an intracellular [Na+] increase which blocks delayed rectifying K+ channels.


Assuntos
Oligodendroglia/ultraestrutura , Bloqueadores dos Canais de Potássio , Receptores de AMPA/agonistas , Receptores de Ácido Caínico/agonistas , Sódio/metabolismo , Animais , Células Cultivadas/fisiologia , Células Cultivadas/ultraestrutura , Eletrofisiologia , Proteínas de Ligação ao GTP/fisiologia , Guanosina 5'-O-(3-Tiotrifosfato)/farmacologia , Guanosina Difosfato/análogos & derivados , Guanosina Difosfato/farmacologia , Camundongos , Camundongos Endogâmicos , Oligodendroglia/fisiologia , Toxina Pertussis , Potássio/metabolismo , Potássio/farmacologia , Sódio/farmacologia , ATPase Trocadora de Sódio-Potássio/fisiologia , Tionucleotídeos/farmacologia , Fatores de Virulência de Bordetella/farmacologia
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