Revealing potential functions of hypothetical proteins induced by genistein in the symbiosis island of Bradyrhizobium japonicum commercial strain SEMIA 5079 (= CPAC 15).

BACKGROUND: Bradyrhizobium japonicum strain SEMIA 5079 (= CPAC 15) is a nitrogen-fixing symbiont of soybean broadly used in commercial inoculants in Brazil. Its genome has about 50% of hypothetical (HP) protein-coding genes, many in the symbiosis island, raising questions about their putative role on the biological nitrogen fixation (BNF) process. This study aimed to infer functional roles to 15 HP genes localized in the symbiosis island of SEMIA 5079, and to analyze their expression in the presence of a nod-gene inducer. RESULTS: A workflow of bioinformatics tools/databases was established and allowed the functional annotation of the HP genes. Most were enzymes, including transferases in the biosynthetic pathways of cobalamin, amino acids and secondary metabolites that may help in saprophytic ability and stress tolerance, and hydrolases, that may be important for competitiveness, plant infection, and stress tolerance. Putative roles for other enzymes and transporters identified are discussed. Some HP proteins were specific to the genus Bradyrhizobium, others to specific host legumes, and the analysis of orthologues helped to predict roles in BNF. CONCLUSIONS: All 15 HP genes were induced by genistein and high induction was confirmed in five of them, suggesting major roles in the BNF process.

Occurrence, quantification, pulse types, and antimicrobial susceptibility of Salmonella sp. isolated from chicken meat in the state of Paraná, Brazil.

The aim of this work was to verify the occurrence, quantification, pulse types, and antimicrobial susceptibility profiles of Salmonella sp. isolated from chicken meat produced and marketed in the state of Paraná, considered to be the state with the highest production of poultry meat in Brazil. Ninety-five of 300 (31.5%) frozen cuts of chicken were found to contain Salmonella sp., and 98 different isolates of Salmonella sp. were cultured from the positive samples. Quantification showed low Salmonella sp. loading, ranging from 0.12 to 6.4 MPN/g. The antimicrobial resistance test was performed against 16 agents from 6 different classes. All isolates were sensitive to meropenem, imipenem, chloramphenicol, and amikacin. The highest resistance rates were observed for nalidixic acid (95%), tetracycline (94%), doxycycline (94%), ampicillin (87%), amoxicillin with clavulanic acid (84%), ceftriaxone (79%), and ciprofloxacin (76%). A total of 84 (85.7%) of the isolates were identified with a multidrug resistant profile, 13 of which were found to have encoding genes extended-spectrum beta-lactamase (ESBL), especially blaCTX-M-2 e blaTEM-1. The major serovars identified were S. Typhimurium (43%) and S. Heidelberg (39%). The third most isolated serovar was S. Ndolo (6%), without previous reports of its presence in poultry meat in Brazil. Molecular characterization of S. Typhimurium and S. Heidelberg isolates by pulsed field gel electrophoresis (PFGE) showed a clonal relationship between all isolates of the same serovar (genetic similarity greater than 80%). Isolates of S. Typhimurium and S. Heidelberg with 100% similarity were found in up to five different geographic regions of the state, showing the potential for the spread of this pathogen in the Paraná poultry chain. Epidemiological surveys like this are important to understand the dynamics of dissemination and to monitor the prevalence of pathogens in the final products of poultry chains. In addition, to know the resistance profile of strains of Salmonella sp. present in food that contributes to the adoption of faster and more effective therapeutic measures, when necessary.

Identification of a mutation in the spike protein cleavage site in Brazilian strains of wild-type bovine coronavirus

The spike (S) protein of coronaviruses, a type I membrane glycoprotein, is primarily responsible for entry into susceptible cells by binding with specific receptors on cells and mediating subsequent virus-cell fusion. The bovine coronavirus (BCoV) S protein is cleaved into two subunits, the N-terminal S1 and the C-terminal S2. The proteolytic cleavage site of S protein is highly conserved among BCoV strains and is located between amino acids 763 and 768 (KRRSRR). This study describes a single mutation in the S protein cleavage site of three Brazilian strains of BCoV detected in diarrheic fecal samples from calves naturally infected. The sequenced PCR products revealed that amino acid sequence of the cleavage site of our strains was KRRSSR, indicating a mutation at amino acid position 767 (R ® S). This amino acid substitution occurred due to a single nucleotide substitution in the sequence of DNA corresponding to the proteolytic cleavage site, CGT to AGT. This is the first description of this nucleotide mutation (C to A), which resulted in the substitution of arginine to serine in the S cleavage site. In this study we speculated the probable effects of this mutation in the proteolytic cleavage site using the murine hepatitis coronavirus (MHV) as a comparative model.

A proteína da espícula (S), uma glicoproteína de membrana do tipo I, é primariamente responsável pela entrada do vírus em células susceptíveis por meio da interação inicial com receptores celulares específicos e subseqüente mediação da fusão vírus-célula. A proteína S do coronavírus bovino (BCoV) é clivada em duas subunidades: a S1, na região N-terminal e a S2, na região C-terminal. O sítio de clivagem proteolítica da proteína S é altamente conservado entre as estirpes de BCoV e está situado entre os aminoácidos 763-768 (KRRSRR). Este estudo descreve uma mutação no sítio de clivagem da proteína S de três estirpes do BCoV detectadas em amostras fecais diarréicas de bezerros naturalmente infectados no Brasil. O seqüenciamento dos produtos de PCR identificou a seqüência de aminoácidos KRRSSR no sítio de clivagem de nossas amostras, indicando uma mutação na posição 767 (R->S). Esta mutação ocorreu devido a uma única substituição de nucleotídeo no sítio de clivagem proteolítica, alterando o códon CGT para AGT. Esta é a primeira descrição desta mutação de nucleotídeo (C para A), que resultou na substituição do aminoácido arginina por serina no sítio de clivagem da proteína S. Neste estudo também são sugeridos os prováveis efeitos desta mutação no sitio de clivagem proteolítica utilizando o coronavírus da hepatite dos camundongos (MHV) como um modelo comparativo.

G and P genotypes of group A rotavirus strains circulating in calves in Brazil, 1996-1999.

Fifty fecal samples from calves with diarrhea, positive for group A rotavirus by enzyme immunoassay (EIA) and polyacrylamide gel electrophoresis (PAGE) were analyzed by a nested multiplex reverse transcription/polymerase chain reaction (Nested multiplex/RT-PCR) for identification of P and G genotypes. Samples were collected between 1996 and 1999 from eight dairy and/or beef cattle herds located in the Mato Grosso do Sul, São Paulo, Goiás and Paraná States, Brazil. Complete genotyping was possible in 44 (88%) of the calf fecal samples. The VP7 gene could not be identified in six (12%) of the samples. Whilst the VP4 (P) gene was identified in 100% of samples. The genotypes of 35 (70%) samples corresponded to the NCDV-like (12%), UK-like (40%), B223-like (16%) and KN-4 (2%) reference rotavirus strains, which are commonly found in cattle. Mixed infections were detected in seven (14%) samples, and genotypes observed in two (4%) samples presented unusual combinations, carrying VP4 and VP7 gene of the bovine group A rotavirus (P[11],G8), in other one carrying a VP4 gene of bovine origin (P[1]) and a VP7 gene of swine origin (G5).