The Helicobacter pylori Genome Project : insights into H. pylori population structure from analysis of a worldwide collection of complete genomes

Helicobacter pylori, a dominant member of the gastric microbiota, shares co-evolutionary history with humans. This has led to the development of genetically distinct H. pylori subpopulations associated with the geographic origin of the host and with differential gastric disease risk. Here, we provide insights into H. pylori population structure as a part of the Helicobacter pylori Genome Project (HpGP), a multi-disciplinary initiative aimed at elucidating H. pylori pathogenesis and identifying new therapeutic targets. We collected 1011 well-characterized clinical strains from 50 countries and generated high-quality genome sequences. We analysed core genome diversity and population structure of the HpGP dataset and 255 worldwide reference genomes to outline the ancestral contribution to Eurasian, African, and American populations. We found evidence of substantial contribution of population hpNorthAsia and subpopulation hspUral in Northern European H. pylori. The genomes of H. pylori isolated from northern and southern Indigenous Americans differed in that bacteria isolated in northern Indigenous communities were more similar to North Asian H. pylori while the southern had higher relatedness to hpEastAsia. Notably, we also found a highly clonal yet geographically dispersed North American subpopulation, which is negative for the cag pathogenicity island, and present in 7% of sequenced US genomes. We expect the HpGP dataset and the corresponding strains to become a major asset for H. pylori genomics

Macro-mineral concentrations in soil and forage in three grassland sites at Zacatecas

Mineral concentration in forage is an important factor for extensive livestock production. Therefore, a study was performed in order to evaluate the soil mineral contents and their relationships with forage mineral concentrations taking into account three grassland sites located at Zacatecas state, México. Soil organic matter (OM) content and pH as well as soil and forage contents of Ca, P, Mg, Na and K were estimated. Soil OM contents were not different (P>0.05) among sites averaging 2.99 %. Soil pH of site 2 was higher (P£0.05) than those of sites 1 and 3. Soil of site 2 had higher P, Ca and Mg concentrations than the minimum contents used as references. Soil contents of Na and K were lower than the reference contents suggesting deficiencies in all three sites. Considering requirements for growing cattle, P, Ca and Na were at insufficient levels in forage from all three sites. Significant correlations (r Pearson) suggest a positive effect of soil P content on forage P and Mg concentrations. Soil P content could affect forage Ca concentration and Ca:P ratio. Other correlations suggest soil Ca negative effects on forage Ca concentration and Ca:P ratio.

Interface effects in the magneto-optical properties of Co nanoparticles in dielectric matrix

3 pages, 3 figures.The authors present a study of the optical and magneto-optical properties of Co nanoparticles embedded in two amorphous dielectric matrices with different refractive indices such as ZrO2 and Al2O3. The nanostructured films were prepared by pulsed laser deposition, and the morphology and structure were studied by different characterization techniques. The optical and magneto-optical (MO) properties of the Co inside the nanoparticles differ from those of the bulk material; in particular, a decrease in the MO constants is found. These properties are found to depend on the nanoparticle size and on the dielectric matrix, due to the different nanoparticle-matrix interfaces appearing in both cases.This work was financed by the Spanish CICYT (MAT2005-06508-C02-01 and MAT2006-03999) and Catalan DURSI (2005SGR00969). Two of the authors (C.C. and J.M.) acknowledge financial support from the MEC through FPI program and from the ESF through I3P program.Peer reviewe

Maíz, potencial productivo y seguridad alimentaria: el caso de San Nicolás de Los Ranchos, Puebla-México

Se expone un modelo tecnológico para aumentar el potencial productivo de maíz de secano, validado con productores de San Nicolás de los Ranchos Puebla-México. Se calculó el Índice de Apropiación de Tecnologías Radicales (IATR) y el Grado de Empleo de Tecnologías Progresivas (GETP); se agruparon a los productores según su rendimiento para diseñar el modelo tecnológico y se estimó la seguridad alimentaria real y potencial. Se encontró que: en el manejo de maíz interaccionan innovaciones radicales y progresivas imperando las segundas; no hay relación directa entre el IATR y rendimientos, pero sí con el GETP; que 29% de los productores son eficientes; el 29% de los productores no poseen seguridad alimentaria y que si los productores de bajo y medio potencial productivo, aplicaran el patrón tecnológico de los productores eficientes, los rendimientos aumentarían, en promedio un 157% y 38%, respectivamente

Calidad de forraje de canola (Brassica napus L.) en floraciones temprana y tardía bajo condiciones de temporal en Zacatecas, México

Canola forage could be an option for diversify crops grown under rainfed conditions and to improve quality forage produced. The objective was to evaluate nutritional composition of canola under rainfed conditions at two plant-growing stages. Fourty eight (48) randomly samples of forage in early bloom (5 % bloom, n= 24) and late bloom (90 % bloom, n= 24) were used within 1 ha plot located in semi-temperate climate at North of Mexico. All samples were dry at 65 °C during 48 h; bromatological and nutritional evaluation were performed using standard methods. Differences (P<0.05) were observed in all variables, averaging 26 vs 12 % crude protein, 47 vs 60 % neutral detergent fiber, 28 vs 52 % acid detergent fiber, 2.56 vs 1.99 % dry matter intake (%BW), 67 vs 48 % DMS, and 133 vs 72 relative forage value, 1.52 vs 0.86 net energy for maintenance (Mcal/kg), respectively for early and late bloom. It is concluded that early bloom canola forage represents better quality because of its protein content and fiber fraction. Estimated energetic value is 1.8 times greater in early bloom compared with late bloom (1.52 vs 0.86 Mcal ENm/kg); and early bloom energetic value is compared with sudan grass.  El objetivo fue evaluar la composición nutricional y el potencial forrajero de la canola en condiciones de temporal, durante dos etapas de crecimiento. Se utilizaron 48 muestras seleccionadas al azar de forraje en floración temprana (5 % floración, n= 24) y tardía (90 % floración, n= 24), recolectadas de una parcela (1 ha) situada en el municipio de Calera de Víctor Rosales, Zacatecas, México, caracterizado por ser un clima semi-templado. Todas las muestras se secaron a 65 °C durante 48 h; las evaluaciones nutricionales y bromatológicas se realizaron utilizando métodos estándar. Se observaron diferencias (P<0.05) en todas las variables estudiadas; la proteína cruda (%) promedió 26 vs 12, fibra detergente neutro (% base seca) 47 vs 60, fibra detergente ácido (% base seca) 28 vs 52, consumo esperado (DMI, % PV) 2.56 vs 1.99, digestibilidad de la materia seca (% base seca) 67 vs 48, valor relativo del forraje 133 vs 72, y la energía neta de mantenimiento (Mcal/kg materia seca) 1.52 vs 0.86, respectivamente para la floración temprana y tardía. Se concluye que el forraje de la canola en la fase de floración temprana presenta una mayor calidad como resultado de sus contenidos de proteína cruda y de la fracción fibra. Comparado con la floración tardía, el valor energético estimado resultó 1.8 veces mayor (1.52 vs 0.86 Mcal ENm/kg) para la floración temprana, este valor energético estimado es similar al del pasto sudán

Eficiencia energética y económica del cultivo de maíz en la zona de amortiguamiento de la Reserva de la Biosfera "La Sepultura", Chiapas, México

Abstract: Energy balance, production capacity of protein-energy and, economic feasibility of three maize production systems were studied: poly-culture maize intercropped with beans (SPM-1), production of landrace maize (SPM-2) and, production of improved maize (SPM-3), located in the ejido California within the Biosphere Reserve "La Sepultura" in the State of Chiapas, Mexico. Derived from a detailed description of production systems, analysis of energy inputs to the system, physical flows and inputs used to produce material (Meul et al., 2007) and analysis of energy efficiency (Funes, 2009) it was found that the production system of landrace maize intercropped with beans showed the highest energy efficiency with 1. 12 Mcal produced, compared to the systems of landrace maize in monoculture and improved maize, which had efficiency ratings of 1.07 and 0.99, respectively. Similarly, the SPM-1 showed the highest energy and protein, capable of meeting the requirements of9 and 23 individuals ha-1 year1, respectively potential. The biggest benefit/cost corresponded to the production system with improved varieties SPM-3. Among the energy and economic factors that increase the cost of production is high dependence on chemical inputs and the use of hired labour. Keywords: Zea mays, food, energy balance, production systemsResumen Se estudió el balance energético, la capacidad de producción de proteína-energía, y la factibilidad económica de tres sistemas de producción de maíz: policultivo maíz intercalado con frijol (SPM-1), producción de maíz criollo (SPM-2) y producción de maíz mejorado (SPM-3), ubicados en el ejido California dentro de la Reserva de la Biosfera "La Sepultura" en el estado de Chiapas, México. Derivado de una detallada descripción de los sistemas productivos, del análisis de ingresos de energía al sistema, flujos de materia física e insumos utilizados para la producción (Meul et al., 2007) y del análisis de la eficiencia energética (Funes, 2009), se encontró que el sistema de producción de maíz criollo intercalado con frijol mostró la mayor eficiencia energética con 1.12 Mcal producida, en comparación a los sistemas de maíz criollo en monocultivo y maíz mejorado, los cuales tuvieron índices de eficiencia de 1.07 y 0.99, respectivamente. De igual forma, el SPM-1 mostró el mayor potencial energético y proteico, capaz de satisfacer los requerimientos de 9 y 23 personas ha-1 año-1, respectivamente. El mayor beneficio/costo correspondió al sistema de producción con variedades mejoradas SPM-3. Entre los factores energéticos y económicos que más encarecen la producción, está la alta dependencia de insumos agroquímicos y el empleo de mano de obra contratada. Palabras-clave: Zea mays; alimentación humana; balance energético; sistemas de producció