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2.
Hong Kong Med J ; 25(3): 228-234, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-31178442

RESUMO

Peanut allergy is the commonest cause of food-induced anaphylaxis in the world, and it can be fatal. There have been many recent improvements to achieve safe methods of peanut desensitisation, one of which is to use a combination of anti-immunoglobulin E and oral immunotherapy. We have treated 27 patients with anti-immunoglobulin E and oral immunotherapy, and report on the outcomes and incidence of adverse reactions encountered during treatment. The dose of peanut protein tolerated increased from a median baseline of 5 to 2000 mg after desensitisation, which is substantially more than would be encountered through accidental ingestion. The incidence of adverse reactions during the escalation phase of oral immunotherapy was 1.8%, and that during the maintenance phase was 0.6%. Most adverse reactions were mild; three episodes were severe enough to warrant withdrawal from oral immunotherapy, but none required epinephrine injection. Preliminary data suggest that unresponsiveness is lost when daily ingestion of peanuts is stopped after the maintenance period.


Assuntos
Alérgenos/administração & dosagem , Arachis/imunologia , Dessensibilização Imunológica/métodos , Hipersensibilidade a Amendoim/terapia , Administração Oral , Adolescente , Alérgenos/imunologia , Criança , Dessensibilização Imunológica/efeitos adversos , Epinefrina/uso terapêutico , Feminino , Antagonistas dos Receptores Histamínicos H1/uso terapêutico , Humanos , Fatores Imunológicos/efeitos adversos , Masculino , Hipersensibilidade a Amendoim/imunologia
3.
Hong Kong Med J ; 20(4): 325-30, 2014 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-24948668

RESUMO

Peanut allergy is one of the commonest food hypersensitivities causing fatal or near-fatal reactions. There is, currently, no preventive treatment and the incidence of severe allergic reactions during peanut desensitisation has limited its clinical use. Anti-immunoglobulin E therapy has been shown to be effective in preventing peanut-induced reactions but it does not result in long-term tolerance. Two important advances have recently been reported. One involves gradual oral introduction of peanut protein to desensitise, whereas the other approach uses a combination of anti-immunoglobulin E and oral peanut immunotherapy. Both approaches could offer a way to desensitise with a far greater margin of safety than has, hitherto, been reported. This article provides an overview of the literature on peanut immunotherapy and describes the experience in a small group of children in Hong Kong who were treated successfully using anti-immunoglobulin E combined with oral peanut desensitisation.


Assuntos
Dessensibilização Imunológica/métodos , Imunoterapia/métodos , Hipersensibilidade a Amendoim/terapia , Administração Oral , Arachis/imunologia , Criança , Feminino , Hong Kong , Humanos , Imunoglobulina E/imunologia , Masculino , Hipersensibilidade a Amendoim/imunologia
4.
Hong Kong Med J ; 18(5): 407-11, 2012 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-23018068

RESUMO

OBJECTIVES. To clarify the use of ultrasonography by determining the frequency of developmental dysplasia of the hip among breech-presented Chinese neonates in Hong Kong. DESIGN. Prospective case series. SETTING. Regional hospital, Hong Kong. PATIENTS. All breech-presented Chinese neonates born during January 2008 to June 2009 were included (except premature neonates). They were examined clinically from birth till the age of 1 year. Ultrasound of the hips was performed at the age of 2 weeks, and X-ray of the pelvis at the age of 1 year. RESULTS. A total of 209 breech-presented neonates were born during the study period; 110 neonates completed all necessary investigations and follow-up. Among the latter, there were three neonates with developmental dysplasia of the hip warranting treatment, which amounted to a frequency of 2.7%. CONCLUSION. Developmental dysplasia of the hip among breech-presented Chinese babies is only slightly less common than in corresponding populations in other regions in the world. Since early diagnosis is important, ultrasonography screening in high-risk cases such as those with breech presentation may be useful.


Assuntos
Apresentação Pélvica , Luxação Congênita de Quadril/epidemiologia , Triagem Neonatal/métodos , Feminino , Seguimentos , Luxação Congênita de Quadril/diagnóstico por imagem , Hong Kong/epidemiologia , Humanos , Lactente , Recém-Nascido , Masculino , Gravidez , Estudos Prospectivos , Ultrassonografia
6.
Lett Appl Microbiol ; 45(4): 398-404, 2007 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-17897382

RESUMO

AIM: To assess potential function of each two-component signal transduction system in the expression of Streptococcus mutans virulence properties. METHODS AND RESULTS: For each two-component system (TCS), the histidine kinase-encoding gene was inactivated by a polymerase chain reaction (PCR)-based deletion strategy and the effects of gene disruption on the cell's ability to form biofilms, become competent, and tolerate acid, osmotic, and oxidative stress conditions were tested. Our results demonstrated that none of the mutations were lethal for S. mutans. The TCS-2 (CiaRH) is involved in biofilm formation and tolerance to environmental stresses, the TCS-3 (ScnRK-like) participates in the survival of cells at acidic pH, and the TCS-9 affects the acid tolerance response and the process of streptococcal competence development. CONCLUSIONS: Our results confirmed the physiological role of the TCS in S. mutans cellular function, in particular the SncRK-like TCS and TCS-9 as they may represent new regulatory systems than can be involved in S. mutans pathogenesis. SIGNIFICANCE AND IMPACT OF THE STUDY: Multiple TCS govern important biological parameters of S. mutans enabling its survival and persistence in the biofilm community.


Assuntos
Biofilmes/crescimento & desenvolvimento , Transdução de Sinais , Streptococcus mutans/fisiologia , Streptococcus mutans/patogenicidade , Deleção de Genes , Mutagênese Insercional , Streptococcus mutans/genética , Virulência
7.
Environ Microbiol ; 5(12): 1309-27, 2003 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-14641576

RESUMO

A new gene cluster, designated sepABC and a divergently transcribed sepR, was found downstream of the two-component todST phosphorelay system that regulates toluene degradation (the tod pathway) in Pseudomonas putida F1 (PpF1). The deduced amino acid sequences encoded by sepABC show a high homology to bacterial proteins known to be involved in solvent efflux or multidrug pumps. SepA, SepB and SepC are referred to be periplasmic, inner membrane and outer membrane efflux proteins respectively. Effects on growth of various PpF1 mutants compared to that of the wild type in the presence of toluene indicated a possible protective role of the solvent efflux system in a solvent-stressed environment. Growth tests with the complemented mutants confirmed the involvement of the Sep proteins in conferring solvent tolerance. The sepR gene encodes a 260-residue polypeptide that is a member of the E. coli IclR repressor protein family. The repressor role of SepR was established by conducting tests with a sep-lacZ transcriptional fusion in Escherichia coli and PpF1, expression of SepR as a maltose-binding fusion protein in a DNA binding assay, and mRNA analysis. Southern hybridization experiments and analysis of the P. putida KT2440 genome sequence indicated that sepR is a relatively rare commodity compared to homologues of the sepABC genes. We developed a whole-cell bioluminescent biosensor, PpF1G4, which contains a chromosomally based sep-lux transcriptional fusion. The biosensor showed significant induction of the sepABC genes by a wide variety of aromatic molecules, including benzene, toluene, ethylbenzene, and all three isomers of xylene (BTEX), naphthalene, and complex mixtures of aliphatic and aromatic hydrocarbons. PpF1G4 represents a second-generation biosensor that is not based on a catabolic promoter but is nonetheless inducible by aromatic pollutants and moreover functional under nutrient-rich conditions.


Assuntos
Proteínas de Bactérias/genética , Técnicas Biossensoriais , Hidrocarbonetos Aromáticos/farmacologia , Proteínas de Membrana Transportadoras/genética , Pseudomonas putida/genética , Proteínas Repressoras/genética , Solventes/farmacologia , Proteínas de Bactérias/química , Proteínas de Bactérias/metabolismo , Sequência de Bases , DNA Bacteriano/química , DNA Bacteriano/isolamento & purificação , Poluentes Ambientais/análise , Poluentes Ambientais/metabolismo , Deleção de Genes , Regulação Bacteriana da Expressão Gênica , Genes Bacterianos , Genes Reporter , Teste de Complementação Genética , Hidrocarbonetos Aromáticos/análise , Hidrocarbonetos Aromáticos/metabolismo , Óperon Lac , Medições Luminescentes , Proteínas de Membrana Transportadoras/metabolismo , Dados de Sequência Molecular , Regiões Promotoras Genéticas , Pseudomonas putida/metabolismo , Proteínas Repressoras/metabolismo , Análise de Sequência de DNA , Homologia de Sequência , Solventes/análise , Solventes/metabolismo , Tolueno/metabolismo , Tolueno/farmacologia , beta-Galactosidase/metabolismo
8.
Cryobiology ; 46(2): 146-52, 2003 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-12686204

RESUMO

We report on microbial contamination of embryos and semen cryopreserved in sealed plastic straws and stored for 6-35 years in liquid nitrogen. There were 32 bacterial and 1 fungal species identified from randomly drawn liquid nitrogen, frozen semen, and embryos samples stored in 8 commercial and 8 research facility liquid nitrogen (LN) tanks. The identified bacteria represented commensal or environmental microorganisms and some, such as Escherichia coli, were potential or opportunistic pathogens for humans and animals. Stenotrophomonas maltophilia was the most common contaminant identified from the samples and was further shown to significantly suppress fertilization and embryonic development in vitro. Analysis of the strains by pulsed field gel electrophoresis revealed restriction patterns with no relatedness indicating that there was no apparent cross-contamination of S. maltophilia strains between the germplasm and liquid nitrogen samples. In addition, no transmission of bovine viral diarrhea virus (BVDV) and bovine herpesvirus-1 (BHV-1) from infected semen and embryos straws to clean germplasm stored in the same LN tanks or LN was detected.


Assuntos
Criopreservação , Embrião de Mamíferos/microbiologia , Contaminação de Equipamentos , Sêmen/microbiologia , Bancos de Tecidos , Animais , Bovinos , Vírus da Diarreia Viral Bovina/isolamento & purificação , Herpesvirus Bovino 1/isolamento & purificação , Nitrogênio , Motilidade dos Espermatozoides , Stenotrophomonas maltophilia/isolamento & purificação
9.
Biotechniques ; 33(3): 526-31, 2002 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-12238762

RESUMO

Using a new method based on a combination of bisulfite reaction, the repair enzyme uracil-DNA glycosylase, and synthetic oligodeoxyribonucleotides, the methylation site of DNA-methyltransferase NlaX (M.NlaX) from Neisseria lactamica was established to be the inner cytosine in the double-stranded pentanucleotide recognition sequence 5'-CCNGG-3' (where N = any nucleoside). 5-Methylcytosine (m5C) type modification by M-N1aX was confirmed by the use of oligonucleotide substrates that contain 5-fluoro-2'-deoxycytidine.


Assuntos
Técnicas de Química Analítica/métodos , DNA Glicosilases , Metilação de DNA , Metilases de Modificação do DNA/química , N-Glicosil Hidrolases/química , Reagentes de Ligações Cruzadas/química , Metilases de Modificação do DNA/isolamento & purificação , DNA Bacteriano/química , Desoxirribonucleases de Sítio Específico do Tipo II/química , Neisseria/química , Neisseria/enzimologia , Neisseria/genética , Sulfitos/química , Uracila-DNA Glicosidase
10.
Br J Radiol ; 74(886): 932-7, 2001 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-11675311

RESUMO

CT is an advanced imaging modality, but the imaging parameters are normally selected subjectively. For standard head examinations, most of the parameters used are consistent amongst different centres, with the exception of large variations in the selection of the tube current-exposure time product (mAs). As a result, CT images may contain unacceptable levels of noise, or the patient may receive excessive radiation. In this study, the maximum anteroposterior diameter (MAPD) was shown to be a good criterion for mAs selection, and could be measured in a pilot view. 200 paediatric brain CT studies were randomly selected to determine the MAPD at the mid brain level. With knowledge of MAPD distribution, a phantom study was performed to determine the relationship between MAPD and the mAs required for consistent and acceptable image noise. It was found that the required mAs increased linearly with MAPD. Assuming the manufacturer's recommended value is "appropriate" for the average MAPD, the appropriate mAs value could be estimated. Using this method, appropriate mAs values were calculated retrospectively for a group of 240 randomly selected paediatric brain CT studies and compared with the actual mAs subjectively determined by the radiographer. Although their average values were similar, the difference between the calculated and actual values deviated markedly in some cases. When the actual mAs was smaller than the calculated value, higher image noise was observed. However, reduction of image noise was barely observed when the applied mAs was larger than the calculated value. Thus, this method is more objective and appropriate for determination of the mAs value for paediatric brain CT than the traditional subjective method.


Assuntos
Encefalopatias/diagnóstico por imagem , Encéfalo/diagnóstico por imagem , Protocolos Clínicos , Crânio/patologia , Tomografia Computadorizada por Raios X/métodos , Encefalopatias/patologia , Criança , Pré-Escolar , Eletrônica , Humanos , Lactente , Imagens de Fantasmas , Doses de Radiação , Tomografia Computadorizada por Raios X/instrumentação
11.
Appl Microbiol Biotechnol ; 55(3): 321-5, 2001 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-11341314

RESUMO

p-Cymene monooxygenase (CMO) from Pseudomonas putida F1 consists of a hydroxylase (CymA1) and a reductase component (CymA2) which initiate pcymene (p-isopropyltoluene) catabolism by oxidation of the methyl group to p-isopropylbenzyl alcohol (p-cumic alcohol). To study the possible diverse range of substrates catalyzed by CMO, the cymA1A2 genes were cloned in an Escherichia coli pT7-5 expression system and the cells were used in transformation experiments. The tested substrates include different substituents on the aromatic ring at the 2 (ortho), 3 (meta) or 4 (para) position relative to the methyl moiety. As a result, a distinct preference was observed for substrates containing at least an alkyl or heteroatom substituent at the para-position of toluene. The conversion rate of 4-chlorotoluene or 4-methylthiotoluene to the corresponding benzyl alcohol was found to be as good as the canonical substrate, p-cymene. But 3-chlorotoluene, 4-fluorotoluene and 4-nitrotoluene were relatively poor substrates. CMO is also capable of producing styrene oxide from styrene. However, the oxidation of 4-chlorostyrene to 4-chlorostyrene oxide was by far the fastest among the substrates used in this study. The various biotransformation products were identified by a combined solid phase microextraction/gas chromatographic-mass spectrometric analytical technique.


Assuntos
Proteínas de Bactérias , Oxirredutases/metabolismo , Pseudomonas putida/enzimologia , Tolueno/análogos & derivados , Álcool Benzílico/análise , Biotransformação , Clonagem Molecular , Compostos de Epóxi/análise , Escherichia coli/genética , Cromatografia Gasosa-Espectrometria de Massas , Oxirredutases/genética , Estireno/farmacologia , Especificidade por Substrato , Tolueno/farmacologia
12.
J Bacteriol ; 183(3): 897-908, 2001 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-11208787

RESUMO

Streptococcus mutans is a bacterium that has evolved to be dependent upon a biofilm "lifestyle" for survival and persistence in its natural ecosystem, dental plaque. We initiated this study to identify the genes involved in the development of genetic competence in S. mutans and to assay the natural genetic transformability of biofilm-grown cells. Using genomic analyses, we identified a quorum-sensing peptide pheromone signaling system similar to those previously found in other streptococci. The genetic locus of this system comprises three genes, comC, comD, and comE, that encode a precursor to the peptide competence factor, a histidine kinase, and a response regulator, respectively. We deduced the sequence of comC and its active pheromone product and chemically synthesized the corresponding 21-amino-acid competence-stimulating peptide (CSP). Addition of CSP to noncompetent cells facilitated increased transformation frequencies, with typically 1% of the total cell population transformed. To further confirm the roles of these genes in genetic competence, we inactivated them by insertion-duplication mutagenesis or allelic replacement followed by assays of transformation efficiency. We also demonstrated that biofilm-grown S. mutans cells were transformed at a rate 10- to 600-fold higher than planktonic S. mutans cells. Donor DNA included a suicide plasmid, S. mutans chromosomal DNA harboring a heterologous erythromycin resistance gene, and a replicative plasmid. The cells were optimally transformed during the formation of 8- to 16-h-old biofilms primarily consisting of microcolonies on solid surfaces. We also found that dead cells in the biofilms could act as donors of a chromosomally encoded antibiotic resistance determinant. This work demonstrated that a peptide pheromone system controls genetic competence in S. mutans and that the system functions optimally when the cells are living in actively growing biofilms.


Assuntos
Proteínas de Bactérias/genética , Biofilmes , Precursores de Proteínas/genética , Streptococcus mutans/genética , Transformação Bacteriana/genética , Sequência de Aminoácidos , DNA Bacteriano , Histidina Quinase , Concentração de Íons de Hidrogênio , Dados de Sequência Molecular , Proteínas Quinases , Transdução de Sinais , Fatores de Tempo
13.
Biochemistry (Mosc) ; 66(12): 1356-60, 2001 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-11812241

RESUMO

A method for determination of a non-methylated deoxycytidine (dC) residue in the recognition site of 5-cytosine DNA-methyltransferases is suggested. The method is based on treatment of methylated DNA by sodium bisulfite and successive reaction of the thus modified DNA with a repair enzyme, uracil-DNA glycosylase. This method was successfully applied to identify NlaX methyltransferase specificity.


Assuntos
DNA Glicosilases , Metilases de Modificação do DNA/metabolismo , DNA/metabolismo , Desoxicitidina/metabolismo , Sítios de Ligação , Metilação de DNA , N-Glicosil Hidrolases/metabolismo , Neisseria/enzimologia , Proteínas Recombinantes/metabolismo , Sulfitos/química , Uracila-DNA Glicosidase
14.
FEMS Microbiol Lett ; 190(2): 185-90, 2000 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-11034277

RESUMO

A bacterial strain KU-7, identified as a Pseudomonas fluorescens by 16S rDNA sequencing, was one of the 12 new isolates that are able to grow on 2-nitrobenzoate as a sole source of carbon, nitrogen, and energy. Resting cells of KU-7 were found to accumulate ammonia in the medium indicating that degradation of 2-NBA proceeds through a reductive route. Metabolite analyses by thin layer chromatography and high pressure liquid chromatography indicated that 3-hydroxyanthranilate is an intermediate of 2-nitrobenzoate metabolism in KU-7 cells. This offers an alternative route to 2-nitrobenzoate metabolism since anthranilate (2-aminobenzoate) or catechol were detected as intermediates in other bacteria. Crude extracts of KU-7 cells converted 2-nitrobenzoate to 3-hydroxyanthranilate with oxidation of 2 mol of NADPH. Ring cleavage of 3-hydroxyanthranilate produced a transient yellow product, identified as 2-amino-3-carboxymuconic 6-semialdehyde, that has a maximum absorbance at 360 nm. The initial enzymes of the 2-nitrobenzoate degradation pathway were found to be inducible since succinate-grown cells produced very low enzyme activities. A pathway for 2-nitrobenzoate degradation in KU-7 was proposed.


Assuntos
Ácido 3-Hidroxiantranílico/metabolismo , Nitrobenzoatos/metabolismo , Pseudomonas fluorescens/metabolismo , Biodegradação Ambiental , Meios de Cultura , Petróleo , Pseudomonas fluorescens/crescimento & desenvolvimento , Pseudomonas fluorescens/isolamento & purificação , Microbiologia do Solo , Microbiologia da Água , Poluição da Água
15.
Appl Environ Microbiol ; 65(11): 5158-62, 1999 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-10543838

RESUMO

We identified chnR, a gene encoding an AraC-XylS type of transcriptional activator that regulates the expression of chnB, the structural gene for cyclohexanone monooxygenase (CHMO) in Acinetobacter sp. strain NCIMB 9871. The gene sequence of chnE, which encodes an NADP(+)-linked 6-oxohexanoate dehydrogenase, the enzyme catalyzing the fifth step of cyclohexanol degradation, was also determined. The gene arrangement is chnB-chnE-chnR. The predicted molecular masses of the three polypeptides were verified by radiolabeling by using the T7 expression system. Inducible expression of cloned chnB in Escherichia coli depended upon the presence of chnR. A transcriptional chnB::lacZ fusion experiment revealed that cyclohexanone induces chnB expression in E. coli, in which a 22-fold increase in activity was observed.


Assuntos
Acinetobacter/enzimologia , Acinetobacter/genética , Aldeído Oxirredutases/genética , Aldeído Oxirredutases/metabolismo , Proteínas de Bactérias , Regulação Bacteriana da Expressão Gênica , Genes Bacterianos , Transativadores/genética , Transativadores/metabolismo , Sequência de Aminoácidos , Sequência Consenso , Escherichia coli/enzimologia , Escherichia coli/genética , Regulação Enzimológica da Expressão Gênica , Dados de Sequência Molecular , Oxigenases/genética , Mapeamento por Restrição , Alinhamento de Sequência , Homologia de Sequência de Aminoácidos
16.
Pediatr Radiol ; 29(10): 770-5, 1999 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-10525786

RESUMO

BACKGROUND: There is no consensus about the optimal milliamperage-second (mAs) settings for computed tomography (CT). Most operators follow the recommended settings of the manufacturers, but these may not be the most appropriate settings. OBJECTIVE: To determine whether a lower radiation dose technique could be used in CT of the paediatric brain without jeopardising the diagnostic accuracy of the images. MATERIALS AND METHODS: A randomised prospective trial. A group of 53 children underwent CT using manufacturer's default levels of 200 or 250 mAs; 47 underwent scanning at 125 or 150 mAs. Anatomical details and the confidence level in reaching a diagnosis were evaluated by two radiologists in a double-blinded manner using a 4-point scoring system. RESULTS: For both readers there was no statistically significant difference in the confidence level for reaching a diagnosis between the two groups. The 95 % confidence intervals and P values were -0.9-1.1 and 0.13 (reader 1) and -1.29-1.37 and 0.70 (reader 2), respectively. Reliability tests showed the results were consistent. CONCLUSIONS: The recommended level may not be the optimum setting. Dose reduction of 40 % is possible on our system in paediatric brain CT without affecting the diagnostic quality of the images.


Assuntos
Encéfalo/diagnóstico por imagem , Tomografia Computadorizada por Raios X , Criança , Pré-Escolar , Método Duplo-Cego , Humanos , Lactente , Variações Dependentes do Observador , Imagens de Fantasmas , Estudos Prospectivos , Doses de Radiação , Reprodutibilidade dos Testes
17.
Environ Sci Technol ; 33(5): 124A-8A, 1999 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-21657760

RESUMO

New molecular tools and an improved understanding of biodegradative processes are slowly increasing prospects for successful technology deployment.

18.
Appl Environ Microbiol ; 64(11): 4363-7, 1998 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-9797291

RESUMO

The replication region of a 100-kb desulfurization plasmid (pSOX) from Rhodococcus sp. strain X309 was localized to a 4-kb KpnI fragment, and its sequence was determined. The amino acid sequence of one of the predicted open reading frames (ORFs) was related to the putative replication (Rep) protein sequences of the mycobacterial pLR7 family of plasmids. Three of the five predicted ORF products were identified by radiolabelling with the Escherichia coli T7 polymerase/promoter system. In E. coli, the Rep protein of pSOX was apparently synthesized in a shortened form, 21.3 kDa instead of the predicted 41.3 kDa, as a result of an internal initiation. This situation is reminescent of that for some bacterial Rep proteins. A shuttle plasmid was constructed with the pSOX origin, pBluescript II KS-, and the chloramphenicol resistance (Cmr) gene from pRF29. This new shuttle plasmid was used to demonstrate expression of the Bacillus subtilis sacB gene in a strain of Rhodococcus, rendering it sensitive to the presence of sucrose.


Assuntos
Escherichia coli/genética , Vetores Genéticos , Fases de Leitura Aberta , Plasmídeos , Replicon , Rhodococcus/genética , Sequência de Aminoácidos , Bacillus subtilis/genética , Bacillus subtilis/metabolismo , Sequência de Bases , Desoxirribonucleases de Sítio Específico do Tipo II , Hexosiltransferases/biossíntese , Hexosiltransferases/genética , Dados de Sequência Molecular , Plasmídeos/biossíntese , Plasmídeos/química , Plasmídeos/genética , Proteínas Recombinantes/biossíntese , Proteínas Recombinantes/química , Mapeamento por Restrição , Alinhamento de Sequência , Homologia de Sequência de Aminoácidos , Sacarose/metabolismo
19.
FEMS Microbiol Lett ; 162(2): 219-26, 1998 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-9627956

RESUMO

An Aroclor 1260 (polychlorinated biphenyl, PCB)-laden soil and one heavily contaminated with polycyclic aromatic hydrocarbons (PAHs) from a secure, engineered landfill site in Québec were analyzed for microbial diversity using a clone library of the 16S rDNA sequences. Phylogenetic analysis revealed that three phyla and their major subdivisions of the domain Bacteria were highly represented in these samples despite the high pollution, particularly by PAHs. None of the 16S rDNA sequences obtained matched known sequences from cultivated bacterial species or from 16S rDNA sequences amplified directly from other environmental samples.


Assuntos
DNA Bacteriano/isolamento & purificação , DNA Ribossômico/isolamento & purificação , Hidrocarbonetos Aromáticos , Microbiologia do Solo , Poluentes do Solo , DNA Bacteriano/genética , DNA Ribossômico/genética , Filogenia , Quebeque , Análise de Sequência
20.
Gene ; 207(1): 9-18, 1998 Jan 19.
Artigo em Inglês | MEDLINE | ID: mdl-9511738

RESUMO

The degradation of 1,2-dichloroethane (DCE) by Xanthobacter autotrophicus GJ10 proceeds via chloroacetaldehyde (CAA), a toxic intermediate in the cells if it is not metabolized further by the NAD(+)-dependent CAA dehydrogenases. Here, we describe the cloning, sequence and expression in Escherichia coli of aldA, a plasmid-located CAA dehydrogenase-encoding gene of GJ10 as well as a chromosomal homolog, designated aldB. The DNA-predicted amino acid (aa) sequences of the two proteins (505 aa in AldA and 506 aa in AldB) are 84% identical. The cloned aldA and aldB genes were verified by their expression in the E. coli T7 polymerase/promoter and the pUC lac promoter systems. The expression level of AldA and its enzymatic activity towards CAA were both higher than those of AldB. In a hybrid construct, the 3'end of aldB was able to complement, although not completely, the corresponding portion of aldA to produce a functional gene. Both AldA and AldB proteins of GJ10 share the highest degree of sequence identity with an acetaldehyde dehydrogenase (ALDH) encoded by acoD of Alcaligenes eutrophus (77.3-78% identity). Together with at least three other ALDHs of prokaryotic origin, these proteins apparently form a special class of ALDHs whose expressions are dependent on RpoN factors. By pulsed-field gel electrophoresis the 225-kb pXAU1 plasmid encoding aldA was shown to be linear.


Assuntos
Aldeído Desidrogenase/genética , Carboxiliases/genética , Bacilos e Cocos Aeróbios Gram-Negativos/genética , Acetaldeído/análogos & derivados , Acetaldeído/metabolismo , Sequência de Aminoácidos , Sequência de Bases , Biodegradação Ambiental , Clonagem Molecular , Escherichia coli/genética , Expressão Gênica , Genes Bacterianos , Dados de Sequência Molecular , Plasmídeos , Regiões Promotoras Genéticas
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