2,060 research outputs found

    Genetic analysis and phenotypic characterization of three novel genes of Rhizobium tropici CIAT899 involved in symbiotic interactions with Phaseolus vulgaris

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    Rhizobium tropici CIAT899 is highly tolerant to many environmental stresses and a good competitor for nodule occupancy of Phaseolus vulgaris. Random transposon mutagenesis was performed with the aim to identify novel genes of this strain involved in symbiosis and stress tolerance. The analysis of the locus disrupted by the Tn5 insertion in mutants 899-PV9 and 899-PV4 led the discovery of three novel genes required for and efficient symbiotic interaction with beans plants. The first gene (syc1) bears significant similarity to voltage-gated chloride channels. A non-polar deletion in this gene caused serious deficiencies for nodule establishment, nodulation competitiveness and N2 fixation, probably due to its reduced ability to invade plant cells and to form stable symbiosomes, as judged by electron transmission microscopy. A second gene (olsC) found downstream of the former was shown to be homologous with aspartyl/asparaginyl β-hydroxylases and involved in the modification of two species of ornithine-containing lipids, presumably by a hydroxylation. A mutant carrying a non-polar deletion in olsC was symbiotically defective, whereas over-expressed OlsC in the complemented strain was related with an acid-sensitive phenotype. The third gene (sigE) codes for a putative σE factor. Analysis performed on the mutant carrying a deletion in this gene also revealed serious deficiencies for nodule development, nodulation competitiveness and N2 fixation when inoculated on bean plants. These three different bacterial activities have not been previously reported as required for the symbiotic interaction of rhizobia with its legume host

    Presence of Adult Companion Goats Favors the Rumen Microbial and Functional Development in Artificially Reared Kids

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    Newborn dairy ruminants are usually separated from their dams after birth and fed on milk replacer. This lack of contact with adult animals may hinder the rumen microbiological and physiological development. This study evaluates the effects of rearing newborn goat kids in contact with adult companions on the rumen development. Thirty-two newborn goat kids were randomly allocated to two experimental groups which were reared either in the absence (CTL) or in the presence of non-lactating adult goats (CMP) and weaned at 7 weeks of age. Blood and rumen samples were taken at 5, 7, and 9 weeks of age to evaluate blood metabolites and rumen microbial fermentation. Next-generation sequencing was carried out on rumen samples collected at 7 weeks of age. Results showed that CTL kids lacked rumen protozoa, whereas CMP kids had an abundant and complex protozoal community as well as higher methanogen abundance which positively correlated with the body weight and blood beta-hydroxybutyrate as indicators of the physiological development. CMP kids also had a more diverse bacterial community (+132 ASVs) and a different structure of the bacterial and methanogen communities than CTL kids. The core rumen bacterial community in CMP animals had 53 more ASVs than that of CTL animals. Furthermore, the number of ASVs shared with the adult companions was over 4-fold higher in CMP kids than in CTL kids. Greater levels of early rumen colonizers Proteobacteria and Spirochaetes were found in CTL kids, while CMP kids had higher levels of Bacteroidetes and other less abundant taxa (Veillonellaceae, Cyanobacteria, and Selenomonas). These findings suggest that the presence of adult companions facilitated the rumen microbial development prior to weaning. This accelerated microbial development had no effect on the animal growth, but CMP animals presented higher rumen pH and butyrate (+45%) and ammonia concentrations than CTL kids, suggesting higher fibrolytic and proteolytic activities. CMP kids also had higher blood beta-hydroxybutyrate (+79%) and lower blood glucose concentrations (-23%) at weaning, indicating an earlier metabolic development which could favor the transition from pre-ruminant to ruminant after the weaning process. Further research is needed to determine the effects of this intervention in more challenging farm conditions

    Anaerobic digestion of road-side-green-cuttings as a poten-tial phytoremediator with different lead concentrations

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    The utilization of roadside-green-cuttings (grass) for anaerobic digestion increases provides an additional possible source of organic waste for use as a renewable energy source. Grass can be used as a substrate to increase biogas yield. Nevertheless, the anaerobic digestion of this kind of waste can be limited due to the fact that it could be contaminated with heavy metals, in particular from traffic emissions and industrial activity. For this reason the biogas production of grass from a busy road was assessed. Samples of roadside-grass were washed with an organosulphide, which is used for the removal of heavy metals from wastewater. A comparison of the anaerobic digestion of washed and unwashed roadside grass was performed. Results showed that the anaerobic digestion of the unwashed grass was much more effective than the washed grass. A second experiment was carried out and co-fermentation of manure and farm-grass was prepared for anaerobic digestion. Lead was added in the concentrations 500, 1000 and 2000 mg Pb2+/kg. The results showed that the higher the lead concentration, the lower the inhibition of the biogas yield. The grass could be acting as phytoremediator for high lead concentrations. The grass could contain organic compounds, which can as-similate heavy metals

    El efecto magnus en el futbol del alto nivel en el Perú y el mundo

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    The title of our article is very suggestive and motivated to understand that the Magnus effect is a property of rotating bodies that move through a fluid, in this case a soccer ball in the air, which has an effect immersed in it. of rotation of the ball which makes it turn in one duration (Roberto Carlos) or in another (Teófilo Cubillas) and this allows it to escape from the view of the goalkeepers, who in both cases remained static for a while. very high internal inhibition process, the Magnus effect also applies to Olympic goals and corner means, but not to the execution of penalty kicks, which is why we can affirm that science governs our actions but that they do not have a clear explanation by Some of the talented players who manage to affirm, in a very empirical way, I hit the ball and he doubled.El título de nuestro artículo es muy  sugerente y motivados para poder entender que El efecto Magnus es una propiedad de los cuerpos en rotación que se trasladan a través de un fluido en este caso un balón de futbol en el aire , el cual lleva inmerso un efecto de rotación del balón el cual hace que este mismo, gire en una duración ( Roberto Carlos) o en otra( Teófilo Cubillas) y ello permita que escape el mismo de la vista de los porteros, que en los dos casos se quedaron estáticos  en un proceso de inhibición interna muy alto,  el efecto Magnus también se aplica a los goles olímpicos y   a los medios córner no así a la  ejecución de tiros de penal es por ello que podemos afirmar que la ciencia gobierna nuestras acciones pero que no tienen una clara explicación por parte de los jugadores talentosos que logra afirmar, en una forma muy empírica yo le pegue al balón y él se  dobló

    The glyoxal budget and its contribution to organic aerosol for Los Angeles, California, during CalNex 2010

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    Recent laboratory and field studies have indicated that glyoxal is a potentially large contributor to secondary organic aerosol mass. We present in situ glyoxal measurements acquired with a recently developed, high sensitivity spectroscopic instrument during the CalNex 2010 field campaign in Pasadena, California. We use three methods to quantify the production and loss of glyoxal in Los Angeles and its contribution to organic aerosol. First, we calculate the difference between steady state sources and sinks of glyoxal at the Pasadena site, assuming that the remainder is available for aerosol uptake. Second, we use the Master Chemical Mechanism to construct a two-dimensional model for gas-phase glyoxal chemistry in Los Angeles, assuming that the difference between the modeled and measured glyoxal concentration is available for aerosol uptake. Third, we examine the nighttime loss of glyoxal in the absence of its photochemical sources and sinks. Using these methods we constrain the glyoxal loss to aerosol to be 0-5 × 10-5 s-1 during clear days and (1 ± 0.3) × 10-5 s-1 at night. Between 07:00-15:00 local time, the diurnally averaged secondary organic aerosol mass increases from 3.2 μg m-3 to a maximum of 8.8 μg m -3. The constraints on the glyoxal budget from this analysis indicate that it contributes 0-0.2 μg m-3 or 0-4% of the secondary organic aerosol mass. Copyright 2011 by the American Geophysical Union
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