Application of young maize plant residues alters the microbiome composition and its functioning in a soil under conservation agriculture: a metagenomics study.

To increase our knowledge on how application of organic material alters soil microbial populations and functionality, shotgun metagenomic sequencing was used to determine the microbial communities and their potential functionality in an arable soil amended with young maize plants (Zea mays L.) in a laboratory experiment after 3 days. The relative abundance of bacterial and viral groups was strongly affected by organic material application, whereas that of the archaeal, protist and fungal groups was less affected. Cellulose degraders with copiotrophic lifestyle (e.g., Betaproteobacteria) were enriched in the amended soil, whereas the groups with slow growing oligotrophic and chemolithoautotrophic metabolism within Bacteria and Archaea were greater in the unamended than in the amended soil. The soil viral structure and richness were also affected. Caudovirales was the dominant viral family, with members of Siphoviridae enriched in the amended soil and members of Myoviridae in the unamended soil. More specialized metabolic traits related to both the degradation of complex C compounds and denitrification related genes were enriched in the young maize plant amended soil than in the unamended soil, whereas nitrification related genes were enriched in the latter. Copiotrophic life-style bacterial groups were enriched in the amended soil, whereas oligotrophic life-style bacterial groups in the unamended soil. Many bacterial and viral phylotypes were affected by the application of young maize plants, but the number of soil fungi, archaea and protists affected was smaller. Metabolic functionality was affected by the application of organic material as the relative abundance of genes involved in the denitrification process was higher in the maize plant amended soil than in the unamended soil and those involved in the nitrification process was higher in the unamended soil.

Application of ammonium to a N limited arable soil enriches a succession of bacteria typically found in the rhizosphere.

Crop residue management and tillage are known to affect the soil bacterial community, but when and which bacterial groups are enriched by application of ammonium in soil under different agricultural practices from a semi-arid ecosystem is still poorly understood. Soil was sampled from a long-term agronomic experiment with conventional tilled beds and crop residue retention (CT treatment), permanent beds with crop residue burned (PBB treatment) or retained (PBC) left unfertilized or fertilized with 300 kg urea-N ha-1 and cultivated with wheat (Triticum durum L.)/maize (Zea mays L.) rotation. Soil samples, fertilized or unfertilized, were amended or not (control) with a solution of (NH4)2SO4 (300 kg N ha-1) and were incubated aerobically at 25 ± 2 °C for 56 days, while CO2 emission, mineral N and the bacterial community were monitored. Application of NH4+ significantly increased the C mineralization independent of tillage-residue management or N fertilizer. Oxidation of NH4+ and NO2- was faster in the fertilized soil than in the unfertilized soil. The relative abundance of Nitrosovibrio, the sole ammonium oxidizer detected, was higher in the fertilized than in the unfertilized soil; and similarly, that of Nitrospira, the sole nitrite oxidizer. Application of NH4+ enriched Pseudomonas, Flavisolibacter, Enterobacter and Pseudoxanthomonas in the first week and Rheinheimera, Acinetobacter and Achromobacter between day 7 and 28. The application of ammonium to a soil cultivated with wheat and maize enriched a sequence of bacterial genera characterized as rhizospheric and/or endophytic independent of the application of urea, retention or burning of the crop residue, or tillage.

Bacterial Communities in Alkaline Saline Soils Amended with Young Maize Plants or Its (Hemi)Cellulose Fraction.

We studied three soils of the former lake Texcoco with different electrolytic conductivity (1.9 dS m-1, 17.3 dS m-1, and 33.4 dS m-1) and pH (9.3, 10.4, and 10.3) amended with young maize plants and their neutral detergent fibre (NDF) fraction and aerobically incubated in the laboratory for 14 days while the soil bacterial community structure was monitored by means of 454-pyrosequencing of their 16S rRNA marker gene. We identified specific bacterial groups that showed adaptability to soil salinity, i.e., Prauseria in soil amended with young maize plants and Marinobacter in soil amended with NDF. An increase in soil salinity (17.3 dS m-1, 33.4 dS m-1) showed more bacterial genera enriched than soil with low salinity (1.9 dS m-1). Functional prediction showed that members of Alfa-, Gamma-, and Deltaproteobacteria, which are known to adapt to extreme conditions, such as salinity and low nutrient soil content, were involved in the lignocellulose degradation, e.g., Marinimicrobium and Pseudomonas as cellulose degraders, and Halomonas and Methylobacterium as lignin degraders. This research showed that the taxonomic annotation and their functional prediction both highlighted keystone bacterial groups with the ability to degrade complex C-compounds, such as lignin and (hemi)cellulose, in the extreme saline-alkaline soil of the former Lake of Texcoco.

Estimación de la edad de Swietenia macrophylla (Meliaceae) a partir del diámetro normal en poblaciones del sureste mexicano

Introducción: Swietenia macrophylla King ("caoba") es la especie arbórea de mayor importancia comercial en el sureste mexicano y utilizada como guía en el manejo forestal, por lo que conocer su edad y tasas de crecimiento es fundamental para la sostenibilidad de los aprovechamientos maderables. Objetivos: Estimar laedad (E t ) a partir del método del 'tiempo de paso' (Tp) y calcular las tasas de crecimiento absoluto (TCA) y relativo (TCR) para Swietenia macrophylla en Quintana Roo, México. Métodos: Se ajustaron ecuaciones para calcular TCA y TCR con remediciones periódicas durante 15 años del diámetro normal (d) en 403 árboles de S. macrophylla en Felipe Carrillo Puerto, Quintana Roo, México; también, se determinaron el Tp y la E t para el cálculo del incremento corriente anual (ICA) e incremento medio anual (IMA), y definir así los turnos comercial y técnico. Resultados: La máxima TCR se alcanzó a los 28 cm de d (0.015 cm año-1) (aplicación de aclareos), mientras que la mayor TCA (0.69 cm año-1) y menor Tp (3.5 años) a los 55 cm de d (turno comercial). El máximo ICA al considerar la E t fue de 1.43 cm en la categoría diamétrica de 50 cm, con un IMA de 0.67 cm año-1 a una edad de 75 años, mientras que el turno técnico (ICA = IMA) se alcanzó a los 96 años (incrementos de 0.78 cm año-1). Conclusiones: A través de mediciones periódicas del diámetro normal en S. macrophylla es posible obtener su edad, además los resultados pueden ser utilizados para elaborar programas de manejo y ejecutar prácticas silvícolas que propicien el incremento diamétrico en Quintana Roo.

Introduction: Swietenia macrophylla King (Mahogany) is the most commercially important tree species in Southeastern of Mexico and is used as a guide in forest management. Therefore, knowing its age and growth rates is essential for the sustainability of timber harvest. Objective: Estimate the age (Et) from the 'step time' (Tp) method and calculate the absolute (TCA) and relative (TCR) growth rates for Swietenia macrophylla in Quintana Roo, Mexico. Methods: Equations were adjusted to calculate TCA and TCR with periodic re-measured for 15 years of the normal diameter (d) in 403 S. macrophylla trees in Felipe Carrillo Puerto, Quintana Roo, Mexico. Tp and Et were determined for the calculation of the annual current increase (ICA) and average annual increase (IMA), to define the commercial and technical shifts. Results: The maximum TCR was reached at 28 cm of d (0.015 cm year-1) (thinning application), whereas the highest TCA (0.69 cm year-1) and lower Tp (3.5 years) at 55 cm of d (commercial shift). The maximum ICA when considering Et was 1.43 cm in the 50 cm of diametric category with an IMA of 0.67 cm year-1 at an age of 75 years, while the technical shift (ICA = IMA) was reached at 96 years (increments of 0.78 cm year-1). Conclusions: Through periodic measurements of the normal diameter in S. macrophylla it is possible to obtain its age, these results also can be used to elaborate management programs and apply silvicultural practices that propitiate the diametric increase in Quintana Roo.

Factors associated to infant mortality in Sub-Saharan Africa.

Half of the 10 million children who die annually in the world are from Sub-Saharan Africa (SSA). The reasons are known, but lack of will and resources avoid the development of sustainable policies. Associated factors to the high infant mortality rate (IMR) in SSA have been investigated in this research. An ecological multi-group study was designed comparing rates within SSA. The dependent variable is the IMR and health services, economic and development indicators are the independent variables. Information and data sources were WHO, World Bank, UNICEF and UNDP (1997-2007). IMR mean value is 92.2 (per 1000 live births) and a relationship with several of the factors could be observed. In the bi-variate analysis direct relationship was observed with maternal mortality rate and an inverse relationship was observed with prenatal care coverage, births assisted by skilled health personnel, gross national income per capita, per capita government expenditure on health, social security expenditure, adult literacy rate, net primary school enrolment rate, population with access to safe drinking water (in urban and rural areas) and with population with access to basic sanitation in rural areas. In the multi-variate analysis IMR had an inverse relationship with children under 5 years with diarrhoea who receive oral re-hydration, with social security expenditure as percentage of general government expenditure on health and with per capita government expenditure on health. The situation in SSA would change if their inhabitants received education and information to demand more equitable polices and better investments from their governments.

Factors Associated to Infant Mortality in Sub-Saharan Africa

Half of the 10 million children who die annually in the world are from Sub-Saharan Africa (SSA). The reasons are known; but lack of will and resources avoid the development of sustainable policies. Associated factors to the high infant mortality rate (IMR) in SSA have been investigated in this research. An ecological multi-group study was designed comparing rates within SSA. The dependent variable is the IMR and health services; economic and development indicators are the independent variables. Information and data sources were WHO; World Bank; UNICEF and UNDP (1997-2007). IMR mean value is 92.2 (per 1000 live births) and a relationship with several of the factors could be observed. In the bi-variate analysis direct relationship was observed with maternal mortality rate and an inverse relationship was observed with prenatal care coverage; births assisted by skilled health personnel; gross national income per capita; per capita government expenditure on health; social security expenditure; adult literacy rate; net primary school enrolment rate; population with access to safe drinking water (in urban and rural areas) and with population with access to basic sanitation in rural areas. In the multi-variate analysis IMR had an inverse relationship with children under 5 years with diarrhoea who receive oral re-hydration; with social security expenditure as percentage of general government expenditure on health and with per capita government expenditure on health. The situation in SSA would change if their inhabitants received education and information to demand more equitable polices and better investments from their governments

Factors associated with maternal mortality in Sub-Saharan Africa: an ecological study.

BACKGROUND: Maternal health is one of the major worldwide health challenges. Currently, the unacceptably high levels of maternal mortality are a common subject in global health and development discussions. Although some countries have made remarkable progress, half of the maternal deaths in the world still take place in Sub-Saharan Africa where little or no progress has been made. There is no single simple, straightforward intervention that will significantly decrease maternal mortality alone; however, there is a consensus on the importance of a strong health system, skilled delivery attendants, and women's rights for maternal health. Our objective was to describe and determine different factors associated with the maternal mortality ratio in Sub-Saharan countries. METHODS: An ecological multi-group study compared variables between many countries in Sub-Saharan Africa using data collected between 1997 and 2006. The dependent variable was the maternal mortality ratio, and Health care system-related, educational and economic indicators were the independent variables. Information sources included the WHO, World Bank, UNICEF and UNDP. RESULTS: Maternal mortality ratio values in Sub-Saharan Africa were demonstrated to be high and vary enormously among countries. A relationship between the maternal mortality ratio and some educational, sanitary and economic factors was observed. There was an inverse and significant correlation of the maternal mortality ratio with prenatal care coverage, births assisted by skilled health personnel, access to an improved water source, adult literacy rate, primary female enrolment rate, education index, the Gross National Income per capita and the per-capita government expenditure on health. CONCLUSIONS: Education and an effective and efficient health system, especially during pregnancy and delivery, are strongly related to maternal death. Also, macro-economic factors are related and could be influencing the others.

Plasma homocysteine in adolescents depends on the interaction between methylenetetrahydrofolate reductase genotype, lipids and folate: a seroepidemiological study.

BACKGROUND: Many publications link high homocysteine levels to cardiovascular disease. In Spain there is little information on the prevalence of hyperhomocysteinaemia and associated vitamin factors among the general population, and less still among children. Cardiovascular risk factors in the childhood population may be related to the appearance of cardiovascular disease at adult age. The aim of this study is to establish a definition of hyperhomocysteinaemia in adolescents and to analyze the influence of vitamin and metabolic factors in homocysteine levels in this population group. METHODS: Descriptive, cross-sectional epidemiological study to estimate serum homocysteine, vitamin B12 and folate levels, as well as plasma total, HDL- and LDL- cholesterol in a schoolgoing population aged 13 to 17 years in Madrid, Spain.Spearman correlation analysis was performed to ascertain quantitative comparison, Pearson's chi2 test (frequency < 5, Fisher) was used for comparison of prevalences, Mann-Whitney U and Kruskal-Wallis test were used for comparison of means and Bonferroni correction was used for post-hoc tests. A multivariate logistic regression model was performed in the multivariate analysis. RESULTS: Based on the classic values for definition of hyperhomocysteinaemia in adults, prevalence of hyperhomocysteinaemia in the study population was: 1.26% for 15 mumol/L; and 2.52% for 12 mumol/L.Deficits in HDL cholesterol and serum folate levels yielded adjusted Odds Ratios (OR) for hyperhomocysteinemia of 2.786, 95% CI (1.089-7.126), and 5.140, 95% CI (2.347-11.256) respectively. Mutation of the methylenetetrahydrofolate reductase (MTHFR) C677T genotype also raises the risk of hyperhomocysteinaemia (CC-->CT: OR = 2.362; 95% CI (1.107-5.042) CC-->TT: OR = 6.124, 95% CI (2.301-16.303)) CONCLUSION: A good definition of hyperhomocysteinaemia in adolescents is the 90th percentile, equivalent to 8.23 mumol/L. Risk factors for hyperhomocysteinaemia are cHDL and folate deficiency, and the MTHFR C677T mutant genotype. No significant effect could be assessed for vitamin B12. Coexistence of all three factors increases the risk of suffering from hyperhomocysteinaemia 87-fold.

[Serum folate levels in adolescent population in Madrid, Spain]. / Folato sérico en población adolescente de la Comunidad de Madrid.

BACKGROUND AND OBJECTIVE: Serum folate concentrations in children are essential to establish values which allow to compare different regions or countries, and raise the possibility of fortifying diet with group B vitamins and folic acid as a secondary prevention against cardiovascular diseases. SUBJECTS AND METHOD: A cross-sectional epidemiological study was performed to assess serum folate levels in school children, aged 13-15 years, in Madrid. Folate and vitamin B12 determinations were determined in blood samples of fasting children. Genotype C677T of methylentetrahydrofolate reductase (MTHFR) enzyme was determined by polymerase chain reaction. RESULTS: Average folate levels obtained in our study were 7.83 nmol/l (95% confidence interval, 7.42 to 8.23 nmol/l). Median was 6.89 nmol/l (interquartilic range: 5.30 to -9.30 nmol/l). No statistically significant differences were found by gender, age or presence of menstruation. Serum folate concentration decreased significantly with the mutation of the C677T genotype for MTHFR. Prevalence of deficits of folate (< 5.3 nmol/l) was 23.8% and raised significantly with the mutation of the C677T genotype for MTHFR: 18.8% for CC, 20.4% for CT, and 46.7% for TT. This effect was mainly observed in girls after menstruation. CONCLUSIONS: Homozygosis mutation in C677T genotype of the enzyme MTHFR induces lower folate levels, mainly in girls after menstruation. 5.3 nmol/l is proposed as a threshold to define deficient serum folate levels in the Spanish adolescent population.

Folato sérico en población adolescente de la Comunidad de Madrid / Serum folate levels in adolescent population in Madrid, Spain

FUNDAMENTO Y OBJETIVO: Conocer los valores séricos de folato en niños es imprescindible para establecerunos percentiles que permitan realizar comparaciones entre regiones o países, asícomo para plantear la suplementación de la dieta con vitaminas del grupo B y ácido fólicocomo prevención secundaria frente a las enfermedades cardiovasculares. El objetivo de este estudioha sido analizar las concentraciones de folatos en adolescentes de la Comunidad de Madrid.SUJETOS Y MÉTODO: Se ha realizado un estudio epidemiológico descriptivo de tipo transversal conel fin de estimar los valores séricos de folato en la población escolar de 13 a 15 años de la Comunidadde Madrid. Se determinaron las concentraciones de folato y vitamina B12 en las muestrasde sangre de 311 adolescentes (141 niños y 170 niñas) obtenidas en ayunas. Se determinóel genotipo C677T de la enzima metilentetrahidrofolato reductasa (MTHFR) por reacción encadena de la polimerasa.RESULTADOS: Los valores medios de folato obtenidos en nuestro estudio fueron de 7,83 nmol/l(intervalo de confianza del 95%, 7,42-8,23 nmol/l) y la mediana fue de 6,89 nmol/l (recorridointercuartílico: 5,30-9,30 nmol/l).No se encontraron diferencias estadísticamente significativas por sexo, edad o presencia o ausenciade menstruación. La concentración sérica de folato disminuyó significativamente con lamutación del genotipo C677T de la enzima MTHFR. La prevalencia de valores deficitarios defolato (< 5,3 nmol/l) fue del 23,8% y aumentó significativamente con el genotipo C677TMTHFR mutado en homocigosis: un 18,8% para CC; un 20,4% para CT, y un 46,7% para TT.Este aumento se produjo en mayor medida en las mujeres a partir de la primera menstruación.CONCLUSIONES: El genotipo mutado C677T en homocigosis de la enzima MTHFR produce déficitde folato, especialmente en mujeres a partir de la pubertad. Se propone el valor de 5,3 nmol/lcomo posible punto de corte para definir el déficit de folato sérico en la población adolescentede nuestro país

BACKGROUND AND OBJECTIVE: Serum folate concentrations in children are essential to establish valueswhich allow to compare different regions or countries, and raise the possibility of fortifyingdiet with group B vitamins and folic acid as a secondary prevention against cardiovascular diseases.SUBJECTS AND METHOD: A cross-sectional epidemiological study was performed to assess serum folatelevels in school children, aged 13-15 years, in Madrid. Folate and vitamin B12 determinationswere determined in blood samples of fasting children. Genotype C677T of methylentetrahydrofolatereductase (MTHFR) enzyme was determined by polimerase chain reaction.RESULTS: Average folate levels obtained in our study were 7.83 nmol/l (95% confidence interval,7.42 to 8.23 nmol/l). Median was 6.89 nmol/l (interquartilic range: 5.30 to –9.30 nmol/l).No statistically significant differences were found by gender, age or presence of menstruation.Serum folate concentration decreased significantly with the mutation of the C677T genotypefor MTHFR. Prevalence of deficits of folate (< 5.3 nmol/l) was 23.8% and raised significantlywith the mutation of the C677T genotype for MTHFR: 18.8% for CC, 20.4% for CT, and46.7% for TT. This effect was mainly observed in girls after menstruation.CONCLUSIONS: Homozygosis mutation in C677T genotype of the enzyme MTHFR induces lowerfolate levels, mainly in girls after menstruation. 5.3 nmol/l is proposed as a threshold to definedeficient serum folate levels in the Spanish adolescent population

Burden of hospital admissions for cervical cancer in Spain during 1999-2002.

Population-based retrospective epidemiological study to estimate the burden of to hospitalizations by cervical cancer in Spain. It was conducted by using hospital discharge data from the national surveillance system for hospital data, Conjunto Mínimo Básico de Datos (CMBD). Records of all patients admitted to hospital with a diagnosis of malignant neoplasm of the cervix (ICD-9-MC codes 180.0-180.9) or carcinoma in situ of cervix (code 233.1) during a four year period (1999-2002), were selected. An annual average of 4,151 hospitalizations with a primary or secondary diagnosis of cervical cancer and 2,761 hospitalizations due to carcinoma in situ were identified. Annually there were 25.5 and 17.0 hospitalizations by cervical cancer and carcinoma in situ per 100,000 women > or =20 years of age, respectively. Hospitalization rate by cervical cancer and carcinoma in situ peaks in between 45 and 59 years of age (39.4 admissions per 100,000 women) and 30 to 44 years of age (32.2 per 100,000 women), respectively. The mean cost of a hospitalization by cervical cancer and carcinoma in situ euro3,098 and euro2,192, respectively. The estimated annual cost of hospitalizations cervical cancer and carcinoma in situ in Spain was 19 million euro.