RNA polymerases in strict endosymbiont bacteria with extreme genome reduction show distinct erosions that might result in limited and differential promoter recognition.

Strict endosymbiont bacteria present high degree genome reduction, retain smaller proteins, and in some instances, lack complete functional domains compared to free-living counterparts. Until now, the mechanisms underlying these genetic reductions are not well understood. In this study, the conservation of RNA polymerases, the essential machinery for gene expression, is analyzed in endosymbiont bacteria with extreme genome reductions. We analyzed the RNA polymerase subunits to identify and define domains, subdomains, and specific amino acids involved in precise biological functions known in Escherichia coli. We also perform phylogenetic analysis and three-dimensional models over four lineages of endosymbiotic proteobacteria with the smallest genomes known to date: Candidatus Hodgkinia cicadicola, Candidatus Tremblaya phenacola, Candidatus Tremblaya Princeps, Candidatus Nasuia deltocephalinicola, and Candidatus Carsonella ruddii. We found that some Hodgkinia strains do not encode for the RNA polymerase α subunit. The rest encode genes for α, ß, ß', and σ subunits to form the RNA polymerase. However, 16% shorter, on average, respect their orthologous in E. coli. In the α subunit, the amino-terminal domain is the most conserved. Regarding the ß and ß' subunits, both the catalytic core and the assembly domains are the most conserved. However, they showed compensatory amino acid substitutions to adapt to changes in the σ subunit. Precisely, the most erosive diversity occurs within the σ subunit. We identified broad amino acid substitution even in those recognizing and binding to the -10-box promoter element. In an overall conceptual image, the RNA polymerase from Candidatus Nasuia conserved the highest similarity with Escherichia coli RNA polymerase and their σ70. It might be recognizing the two main promoter elements (-10 and -35) and the two promoter accessory elements (-10 extended and UP-element). In Candidatus Carsonella, the RNA polymerase could recognize all the promoter elements except the -10-box extended. In Candidatus Tremblaya and Hodgkinia, due to the α carboxyl-terminal domain absence, they might not recognize the UP-promoter element. We also identified the lack of the ß flap-tip helix domain in most Hodgkinia's that suggests the inability to bind the -35-box promoter element.

Germylene-ß-sulfoxide Hemilabile Ligand in Coordination Chemistry.

We describe herein the synthesis of a germylene-ß-sulfoxide ligand, 1, and its abilities in coordination chemistry. Treatment of 1 with metal complexes [W(cod)(CO)4], [Mo(nbd)(CO)4] and [Ni(cod)2] afforded the corresponding (1)-chelated metal complexes (1)-W(CO)4 (2a), (1)-Mo(CO)4 (2b), and (1)-Ni(cod) (4a), clearly showing a bidentate ligation of the metal by the germanium(II) and sulfur centers. Coordination with [Ru(PPh3)3Cl2] afforded an unprecedented bridged bis(ruthenium) complex 3b. In the case of 4a, the hemilability of the bidentate ligand 1 was demonstrated by sulfoxide substitution by a CO ligand.

Iridium complexes featuring a tridentate SiPSi ligand: from dimeric to monomeric 14, 16 or 18-electron species.

In the solid state, the dinuclear iridium complex [µ-Cl-Ir(SiMe2CH2-o-C6H4)2PPh]2, 1, is shown by X-ray diffraction to bear dibenzylsilylphosphine ligands in SiPSi tridentate coordination modes as well as chloride bridges. In C6D6 solution, 1 dissociates into the 14-electron species [IrCl(SiMe2CH2-o-C6H4)2PPh] prone to coordinate one or two L-type ligands such as PR3 (R = Cy, Ph, OEt), CO and CH3CN giving rise to the corresponding mononuclear 16- or 18-electron complexes [IrCl(SiMe2CH2-o-C6H4)2PPh(L)x] (x = 1, 2) as evidenced by X-ray and NMR studies. The dinuclear structure is retained upon reaction with Et3SiH which results in the formation of [µ-Cl,µ-H-Ir2{(SiMe2CH2-o-C6H4)2PPh}2] with a bridging hydride. On the basis of NMR studies, the reaction of the triphenylphosphine complex [IrCl(SiMe2CH2-o-C6H4)2PPh(PPh3)] with LiBHEt3 leads to the hydride complex [IrH(SiMe2CH2-o-C6H4)(η2-H-SiMe2CH-o-C6H4)PPh(PPh3)] in which one SiPSi ligand has been transformed and is now bonded to iridium in a tetradentate mode via P, Si, an agostic Si-H bond, and C of a methine as a result of the activation of one methylene group.

A family of rhodium and iridium complexes with semirigid benzylsilyl phosphines: from bidentate to tetradentate coordination modes.

The synthesis of a new trisbenzylsilanephosphine P{(o-C6H4CH2)SiMe2H}3 (1) is shown to proceed with high yields from P(o-tolyl)3. Compound 1 coordinates to the Rh and Ir dimers [MCl(COD)]2 (M = Rh, Ir) in a tetradentate or tridentate fashion, depending on the strict exclusion of water. The dimeric compounds [ClM(SiMe2CH2-o-C6H4)2P(o-C6H4-CH2SiMe2H)]2, 2Rh and 2Ir, feature a tetradentate coordination of the starting ligand with P and two Si atoms as well as a non-classical agostic Si-H group. The presence of adventitious water in the solvents leads to the formation of two new complexes [(µ2-Cl)2M2(SiMe2CH2-o-C6H4)2P(o-C6H4-CH2SiMe2OSiMe2CH2-o-C6H4-)P(SiMe2CH2-o-C6H4)2], 3Rh and 3Ir, which feature a siloxane bridge through Si-H bond breaking in 2. Reaction of [RhCl(COD)]2 with the bisbenzylsilanephosphine PhP{(o-C6H4CH2)SiMe2H}2 leads to the formation of compound 4Rh which features also a dimeric structure with the SiPSi ligand coordinated through the two silicon atoms, one of which occupies the apical position of a square-pyramidal geometry in the solid state, while the second is disposed equatorially trans to π-donor Cl. Finally, bidentate coordination of a PSi ligand is achieved by reaction of [RhCl(COD)]2 with Ph2P{(o-C6H4CH2)SiMe2H} which leads to the monometallic species [RhCl(SiMe2CH2-o-C6H4-PPh2)2], 5Rh, incorporating two chelating PSi ligands and maintaining a Cl ligand.

Consensus architecture of promoters and transcription units in Escherichia coli: design principles for synthetic biology.

Genetic information in genomes is ordered, arranged in such a way that it constitutes a code, the so-called cis regulatory code. The regulatory machinery of the cell, termed trans-factors, decodes and expresses this information. In this way, genomes maintain a potential repertoire of genetic programs, parts of which are executed depending on the presence of active regulators in each condition. These genetic programs, executed by the regulatory machinery, have functional units in the genome delimited by punctuation-like marks. In genetic terms, these informational phrases correspond to transcription units, which are the minimal genetic information expressed consistently from initiation to termination marks. Between the start and final punctuation marks, additional marks are present that are read by the transcriptional and translational machineries. In this work, we look at all the experimentally described and predicted genetic elements in the bacterium Escherichia coli K-12 MG1655 and define a comprehensive architectural organization of transcription units to reveal the natural genome-design and to guide the construction of synthetic genetic programs.

Efecto del consumo de jugo de tomate de árbol (Cyphomandra betacea) sobre el perfil lipídico y las concentraciones de glucosa en adultos con hiperlipidemia, ecuador / Effect of consumption of tree tomato juice (Cyphomandra betacea) on lipid profile and glucose concentrations in adults with hyperlipidemia, ecuador

En este trabajo se evaluó el efecto del consumo del jugo de tomate de árbol (Cyphomandra betacea) sobre parámetros nutricionales y bioquímicos en 54 voluntarios (44 mujeres y 10 hombres) con edades 45±8 años de Ecuador. Al inicio se les realizó una evaluación nutricional y bioquímica, luego se les invitó a consumir el jugo (100g de fruto en 150 ml de agua) diariamente durante 6 semanas. Finalizado este tiempo, se procedió a realizar la evaluación nutricional y bioquímica nuevamente. La evaluación nutricional determinó 67% de obesidad abdominal. Disminuyendo a 53% después del consumo del jugo de tomate de árbol. El 87% de los voluntarios antes del tratamiento, mostraron hipercolesterolemia; 40,7% y 46,3% tenían los triglicéridos y el LDL elevados y 18,5% valores de glucosa entre 98-130mg/dL. Valores que disminuyeron significativamente en este grupo después de la toma del jugo En general, tanto en voluntarios con y sin sobrepeso se observó disminución significativa de colesterol total, LDL y glucosa; sin cambios significativos en los valores de HDL. El consumo del jugo no afectó la actividad de las enzimas alanina-aminotransferasa ni aspartato-aminotransferasa, tampoco las concentraciones de creatinina, urea y ácido úrico; ni la presión arterial, demostrando que no afecta la función hepática ni renal. Estos resultados indican que el consumo del jugo de tomate de árbol, durante seis semanas, parece ejercer un efecto hipolipemiante y moduladora en el metabolismo de la glucosa y colocan a C betacea como uno de los frutos andinos con alto potencial nutraceutico. Sin embargo, estos aspectos deben ser investigados con más detalles(AU)

In this work the effect of consumption of tree tomato juice (Cyphomandra betacea) was evaluated on nutritional and biochemical parameters in 54 volunteers (44 women and 10 men) aged 45 ± 8 years-Ecuador. A nutritional and biochemical evaluation was performed in volunteers; then they were invited to drink tree tomato juice (100g of fruit in 150 ml of water) daily for 6 weeks. Finished these 6 weeks, volunteers were nutritional and biochemical evaluated again. 67% abdominal obesity was found, decreasing at 53% after drinking the established dosage of juice. 87% of the volunteers before treatment, showed hypercholesterolemia, 40.7% and 46.3% had hypertriglyceridemia and elevated LDL, respectively and 18.5% glucose concentrations between 98-130 mg/dL. These values decrease significantly in this group after drinking tomato juice. In general, Total Cholesterol, LDL and glucose concentrations decrease significantly after drinking tree tomato juice in all the voluntaries with or without overweight. There is no change in HDL concentrations. The consumption of tree tomato juice did not affect the activity of alanine aminotransferase or aspartate aminotransferase enzymes either creatinine, urea and uric acid concentrations, neither blood pressure suggesting that does not affect renal or liver function. These results indicate that consumption of tree tomato juice for six weeks appears to have a lipid-lowering and modulating effect on glucose metabolism, suggesting C betacea as one of the high Andean fruits nutraceutical potential. However, this issue should be investigated in more detail(AU)

Phosphinodi(benzylsilane) PhP{(o-C6H4CH2)SiMe2H}2: a versatile "PSi2Hx" pincer-type ligand at ruthenium.

The synthesis of the new phosphinodi(benzylsilane) compound PhP{(o-C6H4CH2)SiMe2H}2 (1) is achieved in a one-pot reaction from the corresponding phenylbis(o-tolylphosphine). Compound 1 acts as a pincer-type ligand capable of adopting different coordination modes at Ru through different extents of Si-H bond activation as demonstrated by a combination of X-ray diffraction analysis, density functional theory calculations, and multinuclear NMR spectroscopy. Reaction of 1 with RuH2(H2)2(PCy3)2 (2) yields quantitatively [RuH2{[η(2)-(HSiMe2)-CH2-o-C6H4]2PPh}(PCy3)] (3), a complex stabilized by two rare high order ε-agostic Si-H bonds and involved in terminal hydride/η(2)-Si-H exchange processes. A small free energy of reaction (ΔrG298 = +16.9 kJ mol(-1)) was computed for dihydrogen loss from 3 with concomitant formation of the 16-electron species [RuH{[η(2)-(HSiMe2)-CH2-o-C6H4]PPh[CH2-o-C6H4SiMe2]}(PCy3)] (4). Complex 4 features an unprecedented (29)Si NMR decoalescence process. The dehydrogenation process is fully reversible under standard conditions (1 bar, 298 K).