Brucella microti: the genome sequence of an emerging pathogen

<p>Abstract</p> <p>Background</p> <p>Using a combination of pyrosequencing and conventional Sanger sequencing, the complete genome sequence of the recently described novel <it>Brucella </it>species, <it>Brucella microti</it>, was determined. <it>B. microti </it>is a member of the genus <it>Brucella </it>within the <it>Alphaproteobacteria</it>, which consists of medically important highly pathogenic facultative intracellular bacteria. In contrast to all other <it>Brucella </it>species, <it>B. microti </it>is a fast growing and biochemically very active microorganism with a phenotype more similar to that of <it>Ochrobactrum</it>, a facultative human pathogen. The atypical phenotype of <it>B. microti </it>prompted us to look for genomic differences compared to other <it>Brucella </it>species and to look for similarities with <it>Ochrobactrum</it>.</p> <p>Results</p> <p>The genome is composed of two circular chromosomes of 2,117,050 and 1,220,319 base pairs. Unexpectedly, we found that the genome sequence of <it>B. microti </it>is almost identical to that of <it>Brucella suis </it>1330 with an overall sequence identity of 99.84% in aligned regions. The most significant structural difference between the two genomes is a bacteriophage-related 11,742 base pairs insert only present in <it>B. microti</it>. However, this insert is unlikely to have any phenotypical consequence. Only four protein coding genes are shared between <it>B. microti </it>and <it>Ochrobactrum anthropi </it>but impaired in other sequenced <it>Brucella</it>. The most noticeable difference between <it>B. microti </it>and other <it>Brucella </it>species was found in the sequence of the 23S ribosomal RNA gene. This unusual variation could have pleiotropic effects and explain the fast growth of <it>B. microti</it>.</p> <p>Conclusion</p> <p>Contrary to expectations from the phenotypic analysis, the genome sequence of <it>B. microti </it>is highly similar to that of known <it>Brucella </it>species, and is remotely related to the one of <it>O. anthropi</it>. How the few differences in gene content between <it>B. microti </it>and <it>B. suis </it>1330 could result in vastly different phenotypes remains to be elucidated. This unexpected finding will complicate the task of identifying virulence determinants in the <it>Brucella </it>genus. The genome sequence of <it>B. microti </it>will serve as a model for differential expression analysis and complementation studies. Our results also raise some concerns about the importance given to phenotypical traits in the definition of bacterial species.</p

Copper phosphoramidite-catalyzed enantioselective desymmetrization of meso-cyclic allylic bisdiethyl phosphates

A highly regio-, diastereo-, and enantioselective desymmetrization of five-, six-, and seven-membered meso-cyclic allylic bis-diethyl phosphates (2a, 2b, and 2c, respectively) was obtained with diethylzinc, using catalytic amounts of [Cu(OTf)](2).C6H6 and phosphoramidite ligands 5. Enantiomeric excesses of up to 87, 94, and >98% were obtained for the addition of diethylzinc to cyclopentene, cyclohexene, and cycloheptene bis-diethyl phosphates, respectively

Contenidos hepáticos y renales de hierro y cobre en ratas tratadas con cadmio y zinc

The influence of the Cd intraperitoneal (ip), and Cd (ip) + Zn subcutaneous (sc) administration on the Cu and Fe concentrations in liver and kidneys was studied. After five weeks, both Cd and Cd+Zn groups showed an abnormally low liver mass with respect to total body mass. The groups of rats treated with Cd alone presented Fe levels in both liver and kidneys lower than those levels observed in the control group. The levels of Cu in liver maintain approximatelly constant during the time of treatment while the Cu content in kidneys significantly increased after five weeks of treatment. With respect to the animals treated with Cd and Zn, the hepatic content of Fe decreased in the first week but tend to be normal after five weeks which suggest the protector role of Zn against to the hepatic depletion of Fe induced by Cd. Renal Fe as well as renal and hepatic Cu presented a similar behaviour. Significant decreases and significant increases were observed after one and five weeks respectively, which could be related with a higher synthesis of metallothioneins and abnormal redistriibution of essential metals.Se realizó un estudio de la influencia de la administración de Cd vía intraperitoneal (ip), y de Cd (ip) y Zn vía subcutánea (sc) sobre los niveles de Fe y Cu en hígado y riñones. Después de cinco semanas ambos grupos de tratamiento (Cd y Cd+Zn) mostraron pesos de hígados anormalmente bajos con respecto al peso corporal total. Los grupos de ratas tratados sólo con Cd presentaron niveles de Fe en ambos órganos (hígados y riñones) menores que los observado en el grupo control. Los niveles de Cu en hígados permanecen practicamente constantes en función del tiempo de tratamiento mientras que el contenido renal de Cu se incrementó significativamente después de cinco semanas de tratamiento. Con respecto a los grupos de animales tratados con Cd+Zn, el contenido hepático de Fe disminuye durante la primera semana pero tiende a normalizarse después de cinco semanas, lo cual sugiere el papel protector del Zn frente a la depleción hepática de Fe inducida por Cd. El Fe renal así como el Cu renal y hepático presentaron un comportamiento similar. Se observan disminuciones e incrementos significativos después de una y cinco semanas respectivamente, lo cual se relaciona con una mayor síntesis de metalotioneínas y redistribución anómala de los metales esenciales

Multiple technology approach based on stable isotope ratio analysis, Fourier transform infrared spectrometry and thermogravimetric analysis to ensure the fungal origin of the chitosan

Chitosan is a natural polysaccharide which has been authorized for oenological practices for the treatment of musts and wines. This authorization is limited to chitosan of fungal origin while that of crustacean origin is prohibited. To guarantee its origin, a method based on the measurement of the stable isotope ratios (SIR) of carbon δ13C, nitrogen δ15N, oxygen δ18O and hydrogen δ2H of chitosan has been recently proposed without indicating the threshold authenticity limits of these parameters which, for the first time, were estimated in this paper. In addition, on part of the samples analysed through SIR, Fourier transform infrared spectrometry (FTIR) and thermogravimetric analysis (TGA) were performed as simple and rapid discrimination methods due to limited technological resources. Samples having δ13C values above -14.2‱ and below -125.1‱ can be considered as authentic fungal chitosan without needing to analyse other parameters. If the δ13C value falls between -25.1‱ and -24.9‱, it is necessary to proceed further with the evaluation of the parameter δ15N, which must be above +2.7‱. Samples having δ18O values lower than +25.3‱ can be considered as authentic fungal chitosan. The combination of maximum degradation temperatures (obtained using TGA) and peak areas of Amide I and NH2/Amide II (obtained using FTIR) also allows the discrimination between the two origins of the polysaccharide. Hierarchical cluster analysis (HCA) and principal component analysis (PCA) based on TGA, FTIR and SIR data successfully distributed the tested samples into informative clusters. Therefore, we present the technologies described as part of a robust analytical strategy for the correct identification of chitosan samples from crustaceans or fung

Low energy measurement of the 7Be(p,gamma)8B cross section

We have measured the cross section of the 7Be(p,gamma)8B reaction for E_cm = 185.8 keV, 134.7 keV and 111.7 keV using a radioactive 7Be target (132 mCi). Single and coincidence spectra of beta^+ and alpha particles from 8B and 8Be^* decay, respectively, were measured using a large acceptance spectrometer. The zero energy S factor inferred from these data is 18.5 +/- 2.4 eV b and a weighted mean value of 18.8 +/- 1.7 eV b (theoretical uncertainty included) is deduced when combining this value with our previous results at higher energies.Comment: Accepted for publication in Phys. Rev. Let

Laser-induced nonresonant nuclear excitation in muonic atoms

Coherent nuclear excitation in strongly laser-driven muonic atoms is calculated. The nuclear transition is caused by the time-dependent Coulomb field of the oscillating charge density of the bound muon. A closed-form analytical expression for electric multipole transitions is derived and applied to various isotopes; the excitation probabilities are in general very small. We compare the process with other nuclear excitation mechanisms through coupling with atomic shells and discuss the prospects to observe it in experiment.Comment: 7 pages, 5 figure