Analysis of the role of the two flagella of Bradyrhizobium japonicum in competition for nodulation of soybean

Bradyrhizobium japonicum has two types of flagella. One has thin filaments consisting of the 33-kDa flagellins FliCI and FliCII (FliCI-II) and the other has thick filaments consisting of the 65-kDa flagellins FliC1, FliC2, FliC3, and FliC4 (FliC1-4). To investigate the roles of each flagellum in competition for nodulation, we obtained mutants deleted in fliCI-II and/or fliC1-4 in the genomic backgrounds of two derivatives from the reference strain USDA 110: the streptomycin-resistant derivative LP 3004 and its more motile derivative LP 3008. All mutations diminished swimming motility. When each mutant was co-inoculated with the parental strain on soybean plants cultivated in vermiculite either at field capacity or flooded, their competitiveness differed according to the flagellin altered. ΔfliCI-II mutants were more competitive, occupying 64-80% of the nodules, while ΔfliC1-4 mutants occupied 45-49% of the nodules. Occupation by the nonmotile double mutant decreased from 55% to 11% as the water content of the vermiculite increased from 85% to 95% field capacity to flooding. These results indicate that the influence of motility on competitiveness depended on the water status of the rooting substrate.Instituto de Biotecnologia y Biologia Molecula

Analysis of the role of the two flagella of Bradyrhizobium japonicum in competition for nodulation of soybean

Bradyrhizobium japonicum has two types of flagella. One has thin filaments consisting of the 33-kDa flagellins FliCI and FliCII (FliCI-II) and the other has thick filaments consisting of the 65-kDa flagellins FliC1, FliC2, FliC3, and FliC4 (FliC1-4). To investigate the roles of each flagellum in competition for nodulation, we obtained mutants deleted in fliCI-II and/or fliC1-4 in the genomic backgrounds of two derivatives from the reference strain USDA 110: the streptomycin-resistant derivative LP 3004 and its more motile derivative LP 3008. All mutations diminished swimming motility. When each mutant was co-inoculated with the parental strain on soybean plants cultivated in vermiculite either at field capacity or flooded, their competitiveness differed according to the flagellin altered. ΔfliCI-II mutants were more competitive, occupying 64-80% of the nodules, while ΔfliC1-4 mutants occupied 45-49% of the nodules. Occupation by the nonmotile double mutant decreased from 55% to 11% as the water content of the vermiculite increased from 85% to 95% field capacity to flooding. These results indicate that the influence of motility on competitiveness depended on the water status of the rooting substrate.Instituto de Biotecnologia y Biologia Molecula

Sesgos y falacias en la interpretación de procesos argumentativos en el programa Pensamiento Crítico de la Escuela Nacional de Estudios Superiores (UNAM)

This article aims to highlight how cognitive biases influence the perception and interpretation of fallacies in argumentative processes on the assumption that, if biases can be detected and there is conscious training, it is feasible to correct these situations in the interpretation. This article intends to answer the question: How do biases affect the interpretation of fallacies in students? The results from a test inserted in an academic project during four semesters are discussed and compared among group of students enrolled in different degrees at Escuela Nacional de Estudios Superiores, Unidad Morelia, from the Universidad Nacional Autónoma de México. Additionally, these results are compared with the results obtained for the same test by a group of lawyers, all active in their professional field, with the intention of recognizing shared traits with a population that is not associated on a daily basis with the university academic context. The results show that for the interlocutor to detect fallacies in argumentative writing, it is necessary to make biases visible, otherwise, fallacies would be left unnoticed. Additional research seems to be necessary at different levels to further contribute to the interpretation of argumentative texts from its constituting elements such as biases, heuristics, argumentative strategies and fallacies.El objetivo es analizar cómo los sesgos cognitivos influyen en la percepción e interpretación de falacias en textos argumentativos para elucidar una metodología que permita subsanar estas situaciones en la interpretación. Así, para explorar la pregunta ¿de qué forma los sesgos inciden en la identificación e interpretación de falacias en estudiantes? se discuten los resultados de una prueba inserta en un proyecto académico que, a lo largo de cuatro semestres, ha permitido confrontar resultados entre grupos de estudiantes de las distintas licenciaturas de la Escuela Nacional de Estudios Superiores, unidad Morelia, de la Universidad Nacional Autónoma de México. Adicionalmente, los resultados se comparan con una aplicación de la misma prueba a un grupo de juristas activos en su ámbito profesional, con la intención de reconocer rasgos compartidos con una población que no está asociada cotidianamente al contexto académico universitario. Los resultados muestran que evidenciar los sesgos es necesario para que el interlocutor de un texto argumentativo sea capaz de detectar las falacias que, de otra manera, pasan desapercibidas.  Es pertinente el desarrollo de investigaciones adicionales en distintos niveles educativos y ambientes profesionales que permitieran obtener resultados que contribuyan a la interpretación de los textos argumentativos desde los distintos elementos que inciden en ellos: sesgos, heurísticas, estrategias argumentativas y falacias

Soybean Lectin Enhances Biofilm Formation by Bradyrhizobium japonicum in the Absence of Plants

Soybean lectin (SBL) purified from soybean seeds by affinity chromatography strongly bound to Bradyrhizobium japonicum USDA 110 cell surface. This lectin enhanced biofilm formation by B. japonicum in a concentration-dependent manner. Presence of galactose during biofilm formation had different effects in the presence or absence of SBL. Biofilms were completely inhibited in the presence of both SBL and galactose, while in the absence of SBL, galactose was less inhibitory. SBL was very stable, since its agglutinating activity of B. japonicum cells as well as of human group A+ erythrocytes was resistant to preincubation for one week at 60°C. Hence, we propose that plant remnants might constitute a source of this lectin, which might remain active in soil and thus favor B. japonicum biofilm formation in the interval between soybean crop seasons

Soybean lectin enhances biofilm formation by Bradyrhizobium japonicum in the absence of plants

Soybean lectin (SBL) purified fromsoybean seeds by affinity chromatography strongly bound to Bradyrhizobium japonicum USDA 110 cell surface. This lectin enhanced biofilm formation by B. japonicum in a concentration-dependent manner. Presence of galactose during biofilm formation had different effects in the presence or absence of SBL. Biofilms were completely inhibited in the presence of both SBL and galactose, while in the absence of SBL, galactose was less inhibitory. SBL was very stable, since its agglutinating activity of B. japonicum cells as well as of human group A+ erythrocytes was resistant to preincubation for one week at 60°C. Hence, we propose that plant remnants might constitute a source of this lectin, which might remain active in soil and thus favor B. japonicum biofilm formation in the interval between soybean crop seasons.Facultad de Ciencias ExactasInstituto de Biotecnologia y Biologia Molecula

Analysis of the role of the two flagella of Bradyrhizobium japonicum in competition for nodulation of soybean

Bradyrhizobium japonicum has two types of flagella. One has thin filaments consisting of the 33-kDa flagellins FliCI and FliCII (FliCI-II) and the other has thick filaments consisting of the 65-kDa flagellins FliC1, FliC2, FliC3, and FliC4 (FliC1-4). To investigate the roles of each flagellum in competition for nodulation, we obtained mutants deleted in fliCI-II and/or fliC1-4 in the genomic backgrounds of two derivatives from the reference strain USDA 110: the streptomycin-resistant derivative LP 3004 and its more motile derivative LP 3008. All mutations diminished swimming motility. When each mutant was co-inoculated with the parental strain on soybean plants cultivated in vermiculite either at field capacity or flooded, their competitiveness differed according to the flagellin altered. ΔfliCI-II mutants were more competitive, occupying 64-80% of the nodules, while ΔfliC1-4 mutants occupied 45-49% of the nodules. Occupation by the nonmotile double mutant decreased from 55% to 11% as the water content of the vermiculite increased from 85% to 95% field capacity to flooding. These results indicate that the influence of motility on competitiveness depended on the water status of the rooting substrate.Instituto de Biotecnologia y Biologia Molecula

Technological Development in the Use of <em>Allium sativum</em> Aqueous Extracts in the Agricultural Field

The advance in agricultural technology could increase their commercialization, being the agronomic management for each crop an alternative. The management of natural products is a relevant and responsible need, in order to improve the quality and production of food, and to protect the agro-ecosystem biodiversity. Therefore, the aim of this chapter is to present our five-year study advances in mango and rambutan agronomic management with aqueous extract of Allium sativum and the use of natural adherent such as Melipona solani honey that improves the function of the components in the biological processes of the crop. Our results showed that this aqueous extract promotes the emission of vegetative and floral shoots, increases flower development, works as an attractant for pollinators, promotes fruit set, stimulates fruit growth, acts as an insecticide to control thrips and mealybugs and stimulates the production of defense metabolites, such as polyphenol compounds. The use of stingless bee honey as an adherent and the aqueous extract of A. sativum could be a key to potentiate the function of its components in leaves, panicles, flowers and fruits

Strain selection for improvement of Bradyrhizobium japonicum competitiveness for nodulation of soybean

A Bradyrhizobium japonicum USDA 110-derived strain able to produce wider halos in soft-agar medium than its parental strain was obtained by recurrent selection. It was more chemotactic than the wild type towards mannitol and three amino acids. When cultured in minimal medium with mannitol as a single carbon-source, it had one thick subpolar flagellum as the wild type, plus several other flagella that were thinner and sinusoidal. Root adsorption and infectivity in liquid media were 50-100% higher for the selected strain, but root colonization in water-unsaturated vermiculite was similar to the wild type. A field experiment was then carried out in a soil with a naturalized population of 1.8 × 105 soybean-nodulating rhizobia g of soil -1. Bradyrhizobium japonicum strains were inoculated either on the soybean seeds or in the sowing furrows. Nodule occupation was doubled when the strains were inoculated in the sowing furrows with respect to seed inoculation (significant with P<0.05). On comparing strains, nodule occupation with seed inoculation was 6% or 10% for the wild type or selected strains, respectively, without a statistically significant difference, while when inoculated in the sowing furrows, nodule occupation increased to 12% and 22%, respectively (differences significant with P<0.05).Instituto de Biotecnologia y Biologia Molecula

Strain selection for improvement of Bradyrhizobium japonicum competitiveness for nodulation of soybean

A Bradyrhizobium japonicum USDA 110-derived strain able to produce wider halos in soft-agar medium than its parental strain was obtained by recurrent selection. It was more chemotactic than the wild type towards mannitol and three amino acids. When cultured in minimal medium with mannitol as a single carbon-source, it had one thick subpolar flagellum as the wild type, plus several other flagella that were thinner and sinusoidal. Root adsorption and infectivity in liquid media were 50-100% higher for the selected strain, but root colonization in water-unsaturated vermiculite was similar to the wild type. A field experiment was then carried out in a soil with a naturalized population of 1.8 × 105 soybean-nodulating rhizobia g of soil -1. Bradyrhizobium japonicum strains were inoculated either on the soybean seeds or in the sowing furrows. Nodule occupation was doubled when the strains were inoculated in the sowing furrows with respect to seed inoculation (significant with P<0.05). On comparing strains, nodule occupation with seed inoculation was 6% or 10% for the wild type or selected strains, respectively, without a statistically significant difference, while when inoculated in the sowing furrows, nodule occupation increased to 12% and 22%, respectively (differences significant with P<0.05).Instituto de Biotecnologia y Biologia Molecula

Soybean lectin enhances biofilm formation by Bradyrhizobium japonicum in the absence of plants

Soybean lectin (SBL) purified fromsoybean seeds by affinity chromatography strongly bound to Bradyrhizobium japonicum USDA 110 cell surface. This lectin enhanced biofilm formation by B. japonicum in a concentration-dependent manner. Presence of galactose during biofilm formation had different effects in the presence or absence of SBL. Biofilms were completely inhibited in the presence of both SBL and galactose, while in the absence of SBL, galactose was less inhibitory. SBL was very stable, since its agglutinating activity of B. japonicum cells as well as of human group A+ erythrocytes was resistant to preincubation for one week at 60°C. Hence, we propose that plant remnants might constitute a source of this lectin, which might remain active in soil and thus favor B. japonicum biofilm formation in the interval between soybean crop seasons.Facultad de Ciencias ExactasInstituto de Biotecnologia y Biologia Molecula