Current Status and Future Strategy in \u3ci\u3eMegathyrsus maximus\u3c/i\u3e Breeding Program at the Alliance Bioversity - CIAT

Megathyrsus maximus (Jacq.) B.K. Simon & S.W.L. Jacobs is one of the most important grass species cultivated for cattle production in cut and carry systems. There is a need to search for superior hybrids with high potential for mitigation and adaptation to climate change. A big proportion of the M. maximus germplasm, preserved in the CIAT GeneBank has been agronomically characterized and genotypes with desirable traits such as high drought tolerance, high BNI potential (Biological nitrification inhibition), high nutritional quality (biomass production, dry matter, crude protein, acid detergent fiber, neutral detergent fiber and dry matter digestibility) and high seed production have been identified. The Megathyrsus maximus breeding program at the alliance Bioversity-CIAT (Alliance) started in 2016 following simultaneously two breeding schemes (Recurrent Selection based on Specific Combining Ability (RS-SCA) and Reciprocal Recurrent selection (RRS)). To start of RS-SCA scheme, a highly diverse, synthetic, sexual population was created, followed by the establishment of a factorial design using nine apomictic male testers and 30 sexual mothers. The aim of the factorial design was not only to estimate various genetic parameters, but also to identify the best possible apomictic tester with the best Combining Ability. Simultaneously, in order to start the breeding scheme of RRS, two open pollination blocks were established independently, following the heterotic pattern revealed by a population structure study using SSR markers. In the future, we aim to apply simulation based R packages to predict the genetic gain in both scenarios, followed by the validation of the predictions with measurement of genetic gain based on field data, when considering the allocation of resources and logistics required in each scenario

Desarrollo de pensamiento científico por medio de la experimentación

Este trabajo presenta aproximaciones de respuestas a la pregunta ¿Qué habilidades de pensamiento científico se pueden desarrollar por medio de la experimentación en procesos de enseñanza y aprendizaje de las ciencias?. La investigación se ha desarrollado durante los últimos cinco años en el marco de los seminarios de didáctica de la física del programa de Licenciatura en Física de la Universidad Distrital Francisco José de Caldas. Para ello se ha tomado como referente principal una perspectiva de Didáctica de las Ciencias en torno a las dimensiones disciplinar, sociocultural y de interacción, propuesta por la autora de este trabajo, y se ha aplicado una metodología de investigación cualitativa centrada en la intervención docente, tomando la experimentación como objeto de estudio de la didáctica

Host association of cryptosporidium parvum populations infecting domestic ruminants in Spain

A stock of 148 Cryptosporidium parvum DNA extracts from lambs and goat kids selected from a previous study examining the occurrence of Cryptosporidium species and GP60 subtypes in diarrheic lambs and goat kids in northeastern Spain was further characterized by a multilocus fragment typing approach with six mini- and microsatellite loci. Various degrees of polymorphism were seen at all but the MS5 locus, although all markers exhibited two major alleles accounting for more than 75% of isolates. A total of 56 multilocus subtypes (MLTs) from lambs (48 MLTs) and goat kids (11 MLTs) were identified. Individual isolates with mixed MLTs were detected on more than 25% of the farms, but most MLTs (33) were distinctive for individual farms, revealing the endemicity of cryptosporidial infections on sheep and goat farms. Comparison with a previous study in calves in northern Spain using the same six-locus subtyping scheme showed the presence of host-associated alleles, differences in the identity of major alleles, and very little overlap in MLTs between C. parvum isolates from lambs and those from calves (1 MLT) or isolates from lambs and those from goat kids (3 MLTs). The Hunter-Gaston index of the multilocus technique was 0.976 (95% confidence interval [CI], 0.970 to 0.982), which supports its high discriminatory power for strain typing and epidemiological tracking. Population analyses revealed the presence of two host-associated subpopulations showing epidemic clonality among the C. parvum isolates infecting calves and lambs/goat kids, respectively, although evidence of genetic flow between the two subpopulations was also detected

Concepciones alternativas de los estudiantes de la Escuela Normal Superior Distrital María Montessori del grado 902 en torno al concepto de ecosistema

Alternative concepts are important for the teaching-learning process since they should be taken as a basis for the construction of knowledge in the classroom. The present study was developed with the objective of identifying and categorizing the alternative conceptions of 30 students of grade 902 of the Escuela Normal Superior Distrital María Montessori de Bogotá around the concept of ecosystem from the application of a diagnostic instrument; the alternative conceptions of the students were classified in levels 0, 1, 2 and 3 of complexity. Fifty percent of the definitions were located in level 1 of complexity (additive level) and only 10% of the definitions were identified in level 3 of complexity (complex organizational level). The usefulness of images for the detection of alternative conceptions is also identified.Las concepciones alternativas son importantes para el proceso de enseñanza-aprendizaje ya que deben tomarse como base para la construcción de conocimientos en el aula. El presente estudio se desarrolló con el objetivo de identificar y categorizar las concepciones alternativas de 30 estudiantes del grado 902 de la Escuela Normal Superior Distrital María Montessori de Bogotá alrededor del concepto de ecosistema a partir de la aplicación de un instrumento diagnóstico; las concepciones alternativas de los estudiantes fueron clasificadas en los niveles 0, 1, 2 y 3 de complejidad. El 50% de las definiciones se ubicaron en el nivel 1 de complejidad (nivel aditivo) y sólo el 10% de las definiciones se identificaron en el nivel 3 de complejidad (nivel de organización compleja). Se evidencia la utilidad del uso de imágenes para la detección de concepciones alternativas

Review of \u3ci\u3eUrochloa\u3c/i\u3e Breeder’s Toolbox with the Theory of Change and Stage Gate System Approach

Livestock production in the global south is at crossroads as there is a demand to increase Animal Source Foods to address hunger and pressure to lighten the environmental footprint often associated with livestock production. To satisfy both needs, the use of technologies that improve animal performance, while reducing land use and net Greenhouse Gas emissions produced by animals is essential. One of such technologies are Urochloa forage grasses. Urochloa forage grasses are well known for their rusticity and their ability to grow in soils of low fertility and high aluminum content. These characteristics allow Urochloa to grow in areas temporally or spatially less suitable for crop production, but also have made ruminants production profitable in areas that would not be otherwise. However, productivity and sustainability of ruminant production in these areas is likely to fall within the next decade due to climate change unless action is taken. Despite these known benefits of Urochloa forage species, breeding programs have long delayed initiation due to apomixes and differences in ploidy. In the mid-1980s, the development of suitable sexual germplasm allowed crossings, and therefore favoured the emergence of breeding programs. In recent decades, several advances in biology, molecular biology, phenotyping, population genetics, genomics and transcriptomics have generated a plethora of information that ought to be integrated for its use in a single breeding toolbox. We use the Theory of Change and Stage-Gate systems approach to review these advances in research and the utility of the current and future available tools. Further, we address the remaining lack of information, thus bridging the knowledge gap and enabling us to maximize the genetic gain in the different Urochloa breeding programs. In this way, we identify breeding bottlenecks and help to pinpoint priorities for Urochloa research and development

Genotype-by-Environment Interaction in Interspecific \u3cem\u3eUrochloa\u3c/em\u3e Hybrids Using Factor Analytic Models

Environmental factors can influence plant phenotypes shaping the expression of pastures. The ability to test genotypes in multiple environments is critical in a breeding program because important traits are heavily influenced by the environment. Nutritional quality is critical in forage breeding because it affects the rate of live weight gain in livestock as well as the quality of end products such as milk and meat. However, there is not much information on the environmental effect on agronomic and nutritional quality traits in tropical forages. For this reason, the objective of the present study was to investigate the genotype-by-environment interaction in a breeding population of interspecific Urochloa hybrids evaluated for agronomic and nutritional quality traits across four locations in Colombia, using factor analytic mixed models. Phenotypic correlations among traits ranged from 0.26 (plant area vs dry weight) to 0.93 (fresh weight vs dry weight), indicating a strong interaction in some traits. Genetic correlations among environments showed different ranges depending on the variable evaluated. For example, plant height genetic correlations among environments ranged from 0.16 to 0.9, indicating high genotype-byenvironment interaction. The factor analytic analysis revealed that two factors explained more than 60% of the genetic variance in all traits evaluated and that 80% of the environments were clustered in the first factor. Factor analytic biplot indicates that Llanos location differed strongly from other locations evaluated. Based on the results obtained, the factor analytic analysis is a useful tool to stratify environments and identify Urochloa cultivars adapted to different ecological niches

Construcción y análisis de juguetes como estrategia de modelación en enseñanza de la física para grado quinto

Analizamos la construcción y análisis de dos juguetes: el paracaidista y el equilibrista, en el desarrollo de modelos explicativos y procedimientos tecnológicos de niños de grado quinto, en torno a conceptos de física. Se desarrolló una intervención planeada conjuntamente entre un Grupo de investigación universitario, un estudiante de licenciatura en física y la profesora titular de un colegio público de Bogotá. Destacamos el crecimiento de la profesora al reconocer nuevas formas de interactuar en el aula. Los niños dieron muestras de evolución en la construcción de sus modelos explicativos y el estudiante de licenciatura evidenció comprensión de procesos de formación del pensamiento para el desarrollo de ciencia y tecnología

The type VI secretion system of Xanthomonas phaseoli pv. manihotis is involved in virulence and in vitro motility.

BACKGROUND: The type VI protein secretion system (T6SS) is important in diverse cellular processes in Gram-negative bacteria, including interactions with other bacteria and with eukaryotic hosts. In this study we analyze the evolution of the T6SS in the genus Xanthomonas and evaluate its importance of the T6SS for virulence and in vitro motility in Xanthomonas phaseoli pv. manihotis (Xpm), the causal agent of bacterial blight in cassava (Manihot esculenta). We delineate the organization of the T6SS gene clusters in Xanthomonas and then characterize proteins of this secretion system in Xpm strain CIO151. RESULTS: We describe the presence of three different clusters in the genus Xanthomonas that vary in their organization and degree of synteny between species. Using a gene knockout strategy, we also found that vgrG and hcp are required for maximal aggressiveness of Xpm on cassava plants while clpV is important for both motility and maximal aggressiveness. CONCLUSION: We characterized the T6SS in 15 different strains in Xanthomonas and our phylogenetic analyses suggest that the T6SS might have been acquired by a very ancient event of horizontal gene transfer and maintained through evolution, hinting at their importance for the adaptation of Xanthomonas to their hosts. Finally, we demonstrated that the T6SS of Xpm is functional, and significantly contributes to virulence and motility. This is the first experimental study that demonstrates the role of the T6SS in the Xpm-cassava interaction and the T6SS organization in the genus Xanthomonas

VOLUMEN 18, NÚMERO 32 (1989)

MODELO PRELIMINAR DE SEDIMENTACIÓN ACTUAL EN EL GRABEN COLOMBO - ECUATORIANO. Padilla, L. E.; León, L. A.ASPECTOS GEOLÓGICOS Y GEOMORFOLÓGICOS DE COMO EL RÍO CAUCA CORRÍA HACIA EL SUR. Padilla, L. E.; León, L. A.ESTUDIO TEXTURAL Y COMPOSICIONAL DE SEDIMENTOS ACTIVOS DEL RÍO MAGDALENA, ENTRE NEIVA Y BOCAS DE CENIZA. Castiblanco, C. R.; Lombana, P. E.APPLICATION OF SCANNING ELECTRON MICROSCOPE AND X-RAY MICROANALYSIS TECHNIQUES IN THE EVALUATION OF RESERVOIR QUALITY AND PETROLEUM PRODUCTION PROBLEMS. Reyes, R.; Pinzón, P.TÉCNICAS DE EVALUACIÓN DE PROYECTOS CARBONÍFEROS. Ortega, C

Chemical Chaperones Curcumin and 4-Phenylbutyric Acid Improve Secretion of Mutant Factor H R127H by Fibroblasts from a Factor H-Deficient Patient

Factor H (FH) is one of the most important regulatory proteins of the alternative pathway of the complement system. Patients with FH deficiency have a higher risk for development of infections and kidney diseases because of the uncontrolled activation and subsequent depletion of the central regulatory component C3 of the complement system. In this study, we investigated the consequences of the Arg(127)His mutation in FH (FHR127H) previously described in an FH-deficient patient, on the secretion of this protein by skin fibroblasts in vitro. We observed that, although the patient cells stimulated with IFN-gamma were able to synthesize FHR127H, the mutant protein was largely retained within the endoplasmic reticulum (ER), whereas normal human fibroblasts stimulated with IFN-gamma secrete FH without retention in the ER. Moreover, the retention of FHR127H provoked enlargement of ER cisterns after treatment with IFN-gamma. A similar ER retention was observed in Cos-7 cells expressing the mutant FHR127H protein. Despite this deficiency in secretion, we show that the FHR127H mutant is capable of functioning as a cofactor in the Factor I-mediated cleavage of C3. We then evaluated whether a treatment could increase the secretion of FH, and observed that the patient's fibroblasts treated with the chemical chaperones 4-phenylbutiric acid or curcumin increased the secretion rate of FH. We propose that these chemical chaperones could be used as alternative therapeutic agents to increase FH plasma levels in FH-deficient patients caused by secretion delay of this regulatory protein. The Journal of Immunology, 2012, 189: 3242-3248.Fundacao de Amparo a Pesquisa do Estado de Sao PauloFundacao de Amparo a Pesquisa do Estado de Sao PauloConselho Nacional de Pesquisa e Desenvolvimento Cientifico, BrazilConselho Nacional de Pesquisa e Desenvolvimento Cientifico, Brazi