DNA extraction as a didactic strategy to learn about the cell in primary and secondary education

Today’s society is widely influenced by the great scientific and technological advances that have been developed since the last century. This implies that citizens face in their daily problematic situations that require the implementation of scientific skills, establishing the importance of the development of scientific literacy, which allows reflection, reasoning and the establishment of connections to solve them satisfactorily. In this sense, practical work is an optimal tool in the classroom, since they place students at the center of the teaching-learning process, seeking solutions to facts that are part of their daily lives through observation and manipulation, transforming them into school scientific facts and thus acquiring new knowledge. Therefore, this work analyzes a practical experience: DNA extraction. To this end, the structure of DNA is presented, the steps that are usually carried out in any process of extraction of this macromolecule are analyzed and a proposal is designed for Primary Education and another for Compulsory Secondary Education in which students extract DNA from everyday material and acquire knowledge about its structure following the scientific method. As results, both proposals have been validated through an expert judgment, highlighting that they are innovative and attractive to students. In conclusion, it is recommended to implement the proposals as well as to take into account the time needed for their development and the importance of the number of students present in the classroom.La sociedad actual está ampliamente influenciada por los grandes adelantos científicos y tecnológicos que se han desarrollado desde el siglo pasado. Esto implica que la ciudadanía se enfrenta diariamente a situaciones problemáticas que requieren la puesta en marcha de competencias científicas, estableciendo la importancia del desarrollo de la alfabetización científica, que permite la reflexión, el razonamiento y el establecimiento de conexiones para resolverlas de manera satisfactoria. En este sentido, los trabajos de tipo práctico suponen una herramienta óptima en las aulas, puesto que sitúan al alumnado en el centro del proceso de enseñanza-aprendizaje, buscando soluciones a hechos que forman parte de su vida cotidiana mediante la observación y la manipulación, transformándolos en hechos científicos escolares y adquiriendo así nuevos conocimientos. Por todo ello, en este trabajo se analiza una experiencia práctica: la extracción de ADN. A tal efecto, se presenta la estructura de ADN, se analizan los pasos que suelen llevarse a cabo en cualquier proceso de extracción de esta macromolécula y se diseña una propuesta para Educación Primaria y otra para Educación Secundaria Obligatoria en las que los estudiantes extraen ADN de material cotidiano y adquieren conocimientos sobre su estructura siguiendo el método científico. Como resultados, ambas propuestas han sido validadas a través de un juicio de expertos destacando que son innovadoras y atractivas para los alumnos. Como conclusión se recomienda implementar las propuestas, así como tener en cuenta el tiempo necesario para su desarrollo y la importancia del número de alumnos presentes en el aula

Isolation of Bacteria with Antifungal Activity against the Phytopathogenic Fungi Stenocarpella maydis and Stenocarpella macrospora

Stenocarpella maydis and Stenocarpella macrospora are the causal agents of ear rot in corn, which is one of the most destructive diseases in this crop worldwide. These fungi are important mycotoxin producers that cause different pathologies in farmed animals and represent an important risk for humans. In this work, 160 strains were isolated from soil of corn crops of which 10 showed antifungal activity against these phytopathogens, which, were identified as: Bacillus subtilis, Pseudomonas spp., Pseudomonas fluorescens, and Pantoea agglomerans by sequencing of 16S rRNA gene and the phylogenetic analysis. From cultures of each strain, extracellular filtrates were obtained and assayed to determine antifungal activity. The best filtrates were obtained in the stationary phase of B. subtilis cultures that were stable to the temperature and extreme pH values; in addition they did not show a cytotoxicity effect against brine shrimp and inhibited germination of conidia. The bacteria described in this work have the potential to be used in the control of white ear rot disease

Aplicaciones de la biología molecular: identificación del basidiomiceto Trametes sp. I-62 y Expresión heteróloga del gen cglcc1 en Kluyveromyces lactis y Yarrowia lipolytica

Tesis doctoral inédita leída en la Universidad Autónoma de Madrid, Departamento de Biología Molecular. Fecha de lectura: 24-01-200

Satisfacción del alumnado de Educación Superior a distancia ante el diseño de actividades colaborativas

La proliferación de la modalidad online en la educación superior es una tendencia en alza tanto en España como en el resto de Europa (Lima & Siebra, 2021; Money & Dean, 2019; Stone, 2017). Estos entornos de aprendizaje poseen muchas ventajas en la gestión del tiempo y el espacio para el estudio, pero presentan ciertas dificultades en lo que respecta a la participación de los estudiantes en diseños de instrucción colaborativa en la impartición de las sesiones de clase, sobre todo por la irregularidad de la presencia de los asistentes (Smith et al., 2011), lo que hace de los trabajos de aprendizaje colaborativos en la educación online un reto a afrontar por parte de los docentes

Emociones y adquisición de conocimiento sobre la luz y los colores mediante un aprendizaje basado en proyectos en educación primaria

El objetivo de este trabajo ha sido analizar el efecto de un aprendizaje basado en proyectos, utilizando el método científico, en la enseñanza de los contenidos sobre la luz y los colores y las emociones experimentadas por el alumnado. En la experiencia participaron 32 alumnos de 5.º y 6.º de educación primaria. Se utilizó una metodología cuantitativa, con un diseño preexperimental pretest y postest. Los resultados muestran que hubo un efecto alto al aumentar los conocimientos adquiridos por los estudiantes tras la implementación de la propuesta. La actividad se ha valorado de forma muy positiva, especialmente en las dimensiones de interacción-colaboración y aprendizaje. Además, ha generado emociones positivas con un efecto alto sin modificación de las emociones negativas. Dichos resultados no se vieron influidos por el sexo o el curso al que pertenecían los estudiantes.The aim of this work has been to analyze the effect of project-based learning, using the scientific method, on improving the learning process of light and colours and on the emotions experienced by the students. Thirty-two 5th and 6th grade primary school students participated in the experience. A quantitative methodology was used, with a pre-experimental pretest and post-test design. The results show that there was a high effect on increasing the knowledge acquired by the students after the implementation of the proposal. They rated the activity very positively, especially in the dimensions of interaction-collaboration and learning. It also generated positive emotions with a high effect without modifying negative emotions. These results were not influenced by gender or the grade to which the students belonged

Biotecnología por colores: impacto en el rendimiento académico del alumnado de Educación Secundaria

La Biotecnología es un área de conocimiento multidisciplinar que proporciona un ejemplo claro para los estudiantes de la aplicación de muchos de los conceptos vistos en ciencias naturales, especialmente en Biología. Desde el siglo XX, la enseñanza y el aprendizaje de las ciencias se ha convertido en materia esencial de investigación educativa. La didáctica de las ciencias presenta un carácter interdisciplinar, al aunar competencias del área de las ciencias, de la historia de la ciencia, de la psicología y de la pedagogía

Use of water hyacinth as a substrate for the production of filamentous fungal hydrolytic enzymes in solid-state fermentation

The objective of the present work was to evaluate the water hyacinth (WH) as a substrate for the production of hydrolytic enzymes (cellulases and hemicellulases) of 100 strains of filamentous fungi under conditions of solid growth. Five fungal strains, identified as Trichoderma harzianum, Trichoderma atroviride, Penicillium griseofulvum, Penicillium commune and Aspergillus versicolor, were selected and studied for their ability to grow on water hyacinth as a substrate and carbon source only, evaluating hydrolytic enzymatic activities (α-l-arabinofuranosidase, cellulase, xylanase and β-d-xylopyranosidase) and extracellular protein per g of water hyacinth dry matter (gdm). The five strains selected were able to produce the four enzymes studied; however, T. harzianum strain PBCA produces the highest xylanase (149.3 ± 14.3 IU/gdm at 108 h), cellulase (16.4 ± 0.6 IU/gdm at 84 h) and β-d-xylopyranosidase (127.7 ± 14.8 IU/gdm at 48 h). In contrast, the fungus with the highest α-l-arabinofuranosidase activity was A. versicolor, with 129.8 ± 13.3 IU/gdm after 108 h. In conclusion, T. harzianum showed the best production of the hydrolytic enzymes studied, using as a matrix and carbon source, water hyacinth. In addition, catalytic activities of arabinofuranosidase and xylopyranosidase were reported for the first time in T. versicolor and T. harzianum.FONCICYT-C002-2008-1 ALA/127249 projec

Effect of Biological and Chemical Pre-treatment on the Hydrolysis of Corn Leaf

Hydrolysis of corn leaf utilizing two treatment sequences was carried out in this study. The first treatment was chemical and involved subjecting the corn leaf to an alkaline pre-treatment and then to a smooth acid hydrolysis. The second consisted of biological delignification using the strain Trametes sp. 44 H88, followed by enzymatic hydrolysis using the enzymatic extract produced by Trichoderma sp. H88. The ligninolytic extract produced by Trametes sp. 44 H88 was used to detoxify the hydrolyzate. The results indicate that biological pre-treatment with delignification is more favorable and improves the subsequent hydrolysis, regardless of whether the hydrolysis is chemical or biological. The chemical treatment sequence obtained 80% conversion of monosaccharides, while the biological treatment sequence resulted in a 87% conversion rate. Finally, the use of the ligninolytic extract for the dephenolization of the hydrolyzate reduced the presence of compounds of phenolic origin by 23%

Use of water hyacinth as a substrate for the production of filamentous fungal hydrolytic enzymes in solid-state fermentation

International audienceThe objective of the present work was to evaluate the water hyacinth (WH) as a substrate for the production of hydrolytic enzymes (cellulases and hemicellulases) of 100 strains of filamentous fungi under conditions of solid growth. Five fungal strains, identified as Trichoderma harzianum, Trichoderma atroviride, Penicillium griseofulvum, Penicillium commune and Aspergillus versicolor, were selected and studied for their ability to grow on water hyacinth as a substrate and carbon source only, evaluating hydrolytic enzymatic activities (α-l-arabinofuranosidase, cellulase, xylanase and β-d-xylopyranosidase) and extracellular protein per g of water hyacinth dry matter (gdm). The five strains selected were able to produce the four enzymes studied; however, T. harzianum strain PBCA produces the highest xylanase (149.3 ± 14.3 IU/gdm at 108 h), cel-lulase (16.4 ± 0.6 IU/gdm at 84 h) and β-d-xylopyranosidase (127.7 ± 14.8 IU/gdm at 48 h). In contrast, the fungus with the highest α-l-arabinofuranosidase activity was A. versicolor, with 129.8 ± 13.3 IU/gdm after 108 h. In conclusion, T. harzi-anum showed the best production of the hydrolytic enzymes studied, using as a matrix and carbon source, water hyacinth. In addition, catalytic activities of arabinofuranosidase and xylopyranosidase were reported for the first time in T. versicolor and T. harzianum