Análisis de la adaptación de la fase endosimbiótica de Rhizobium leguminosarum bv. viciae a diferentes hospedadores

Los rizobios son alfa-proteobacterias capaces de infectar las raíces de las leguminosas e inducir en las mismas la formación de un nuevo órgano, el nódulo radicular. En dicho nódulo las células bacterianas, diferenciadas en bacteroides especializados en la fijación de nitrógeno, están rodeadas de una membrana peribacteroidal a través de cual la planta controla el intercambio de nutrientes hacia y desde el bacteroide. La adaptación de las bacterias al estilo de vida simbiótico es el resultado de un proceso de co-evolución entre ambos socios en el que se produce el intercambio de fuentes carbonadas y nitrógeno fijado en forma de amonio. En el proceso de establecimiento de la simbiosis se han descrito compuestos de diversa naturaleza química (flavonoides, lipoquitooligosacáridos, EPS) que median un reconocimiento específico entre el rizobio y la leguminosa.1 Sin embargo, el intercambio de señales no termina con la formación del nódulo. El funcionamiento de la simbiosis Rhizobium-leguminosa supone el ajuste metabólico de ambos componentes simbióticos en proceso cuyos detalles aún se desconocen. Uno de los objetivos de nuestro laboratorio se centra en el estudio de la adaptación de Rhizobium a la simbiosis analizando cómo la bacteria responde al ambiente nodular proporcionado por la planta. Recientemente se ha descrito que en el caso de las leguminosas que inducen nódulos indeterminados (con actividad meristemática persistente) como Medicago, Pisum, o Vicia, la planta envía al bacteroide una batería de múltiples péptidos denominados NCR (Nodule-specific Cystein-Rich). de los que no se conoce la función concreta, aunque se ha demostrado que algunos de ellos son capaces de inducir modificaciones en células en cultivo similares a las descritas en bacteroides (inhibición de la división celular, endorreduplicación y alteraciones en la permeabilidd de la membrana).2 La hipótesis actual es que la acción combinada de los NCR controla parcial o totalmente la fisiología de la bacteria induciendo su diferenciación en bacteroide y convirtiéndole en algo similar a un ?esclavo metabólico? cuya función esencial es la fijación de nitrógeno para su aporte a la planta, interfiriendo con múltiples procesos fisiológicos. En el caso de rizobios capaces de establecer simbiosis con distintas leguminosas, como es el caso de Rhizobium leguminosarum bv viciae con Pisum, Lens, Vicia y Lathyrus, es de esperar que los bacteroides inducidos en cada planta encuentren un hábitat intracelular distinto si cada planta aporta un complemento de péptidos diferente. En esas condiciones el estudio de la respuesta de la bacteria a cada uno de esos hábitats podría aportar información relevante sobre los caracteres que permiten la adaptación de Rhizobium al estilo de vida intracelular en los nódulos de las leguminosas. En este trabajo se trata de evaluar la importancia de caracteres de adaptación al hospedador en la asociación simbiótica entre Rhizobium leguminosarum bv viciae (Rlv) y plantas leguminosas. Para ello se ha realizado la comparación de los perfiles proteómicos de células endosimbióticas de Rlv UPM791 inducidas en nódulos de lenteja (Lens culinaris) y guisante (Pisum sativum). Dichos perfiles se obtuvieron mediante análisis LC-MS de extractos de bacteroides, complementado con marcaje diferencial empleando la metodología iTRAQ. Este análisis ha revelado la existencia de diferencias en la expresión de un número significativo de proteínas codificadas en distintas partes del genoma bacteriano. Entre estas proteínas se han identificado proteínas de respuesta a estrés, un regulador transcripcional de tipo GntR, y otras proteínas que podrían tener un papel en el metabolismo de C/N en el bacteroide. Estos datos sugieren que las bacterias encuentran ambientes distintos en distintos hospedadores induciendo respuestas de adaptación diferenciales. Dos de las proteínas identificadas, denominadas DABA y AMYDO, se encuentran codificadas en el plásmido simbiótico de la bacteri

Senescence-associated proteolysis induced by abiotic and biotic stresses in barley leaves

Leaf senescence is a recycling process characterized by a massive degradation of macromolecules to relocalize nutrients from leaves to growing or storage tissues. Our aim is to identify and analyze the C1A Cysteine ‐Protease (CysProt) family members from barley (35 cathepsin L‐,3B‐,1Hand3F‐like) involved in leaf senescence, to study their modulation by their specific inhibitors (cystatins) and to determine their roles mediated by abiotic (darkness and N starvation) and biotic (pathogens and pest) stresses

Mental Health Disturbance after a Major Earthquake in Northern Peru: A Preliminary, Cross-Sectional Study

Little has been studied in Peru on the mental health repercussions after a major earthquake.We aimed to explore the factors associated with depressive and anxiety symptoms in people whoexperienced a 6.1 magnitude earthquake in Piura, Peru, on 30 July 2021. A preliminary cross-sectional study was conducted in the general population between August–September 2021. An onlinequestionnaire was provided using PHQ-9, GAD-7, and other relevant measures. Generalized linearmodels were applied. Of the 177 participants, the median age was 22 years, the majority were female(56%), and many experienced depressive (52%) or anxiety symptoms (52%). Presence of depressivesymptoms was associated with a personal history of mental disorder, moderate housing damage,social/material support from politicians, moderate food insecurity, and insomnia. Presence of anxietysymptoms was associated with physical injury caused by the earthquake, mild food insecurity, andinsomnia. The development of depressive and anxiety symptoms following the 2021 earthquakeexperienced in Piura depended on multiple individual and socioeconomic factors. Additional studiesshould reinforce the factors identified here given the methodological limitations, such as the studydesign, sampling method, and sample size. This would lead to effective intervention measures tomitigate the impact of earthquakes on mental health

Lactic Acid Yield Using Different Bacterial Strains, Its Purification, and Polymerization through Ring-Opening Reactions

Laboratory-scale anaerobic fermentation was performed to obtain lactic acid from lactose, using five lactic acid bacteria: Lactococcus lactis, Lactobacillus bulgaricus, L. delbrueckii, L. plantarum, and L. delbrueckii lactis. A yield of 0.99 g lactic acid/g lactose was obtained with L. delbrueckii, from which a final concentration of 80.95 g/L aqueous solution was obtained through microfiltration, nanofiltration, and inverse osmosis membranes. The lactic acid was polymerized by means of ring-opening reactions (ROP) to obtain poly-DL-lactic acid (PDLLA), with a viscosity average molecular weight (Mv) of 19,264 g/mol

Boro-nitriding coating on pure iron by powder-pack boriding and nitriding processes

To alleviate spallation and crack difficulties exhibited by a borided metallic surface when it is subjected to a normal, heavy and sliding load under dry conditions, a boron nitride coating was produced on pure iron in two stages: boriding the iron surface at 950 °C for 6 h and then nitriding the pre-borided iron at 550 °C for 6 h. The powder-pack technique was used in both stages. XRD measurements confirmed that the grown layers were nitrides and duplex borides. The produced diffusion of the layers reached 240 µm in depth as measured by SEM images. The measured microhardness across the case favoured the interphase cohesion between the iron nitrides and iron borides layers. Consequently, the multicomponent coating exhibited superior wear resistance to an applied normal load under dry sliding contact conditions in comparison to borided iron

Accelerated inbreeding depression suggests synergistic epistasis for deleterious mutations in Drosophila melanogaster

Epistasis may have important consequences for a number of issues in quantitative genetics and evolutionary biology. In particular, synergistic epistasis for deleterious alleles is relevant to the mutation load paradox and the evolution of sex and recombination. Some studies have shown evidence of synergistic epistasis for spontaneous or induced deleterious mutations appearing in mutation-accumulation experiments. However, many newly arising mutations may not actually be segregating in natural populations because of the erasing action of natural selection. A demonstration of synergistic epistasis for naturally segregating alleles can be achieved by means of inbreeding depression studies, as deleterious recessive allelic effects are exposed in inbred lines. Nevertheless, evidence of epistasis from these studies is scarce and controversial. In this paper, we report the results of two independent inbreeding experiments carried out with two different populations of Drosophila melanogaster. The results show a consistent accelerated inbreeding depression for fitness, suggesting synergistic epistasis among deleterious alleles. We also performed computer simulations assuming different possible models of epistasis and mutational parameters for fitness, finding some of them to be compatible with the results observed. Our results suggest that synergistic epistasis for deleterious mutations not only occurs among newly arisen spontaneous or induced mutations, but also among segregating alleles in natural populationsWe acknowledge the support by Uvigo Marine Research Centre funded by the “Excellence in Research (INUGA)” Programme from the Regional Council of Culture, Education and Universities, with co-funding from the European Union through the ERDF Operational Programme Galicia 2014-2020. This work was funded by Agencia Estatal de Investigación (AEI) (CGL2016-75904-C2-1-P), Xunta de Galicia (ED431C 2016-037) and Fondos Feder: “Unha maneira de facer Europa.” SD was founded by a predoctoral (FPI) grant from Ministerio de Economía y Competitividad, SpainS

7th Drug hypersensitivity meeting: part two

No abstract availabl