REDI - Digital Repository of the National Agency of Research and Innovation
Not a member yet
4796 research outputs found
Sort by
Leptospira yasudae sp. nov. and Leptospira stimsonii sp. nov., two new species of the pathogenic group isolated from environmental sources.
No full textABSTRACT: Four spirochetes (F1T, B21, YaleT and AMB6-RJ) were isolated from environmental sources: F1T and B21 from soils of an urban slum community in Salvador (Brazil), YaleT from river water in New Haven, Connecticut (USA) and AMB6-RJ from a pond in a horse farm in Rio de Janeiro (Brazil). Isolates were helix-shaped, aerobic, highly motile and non-virulent in a hamster model of infection. Draft genomes of the strains were obtained and analysed to determine the relatedness to other species of the genus Leptospira . The analysis of 498 core genes showed that strains F1T/B21 and YaleT/AMB6-RJ formed two distinct phylogenetic clades within the ?Pathogens? group (group I). The average nucleotide identity (ANI) values of strains F1T/B21 and YaleT/AMB6-RJ to other previously described Leptospira species were below <84?%?and <82?%, respectively, which confirmed that these isolates should be classified as representatives of two novel species. Therefore, we propose Leptospira yasudae sp. nov. and Leptospira stimsonii sp. nov. as new species in the genus Leptospira . The type strains are F1T (=ATCC-TSD-163=KIT0259=CLEP00287) and YaleT (=ATCC-TDS-162=KIT0258=CLEP00288), respectively
Mycorrhizal fungi compromise production of endophytic alkaloids, increasing plant susceptibility to an aphid herbivore.
No full textABSTRACT.- Symbiosis plays a critical role in plant biology. Temperate grasses often associate with several symbiotic fungi simultaneously, including Epichloë endophytes and arbuscular mycorrhizal (AM) fungi, in shoots and roots, respectively. These symbionts often modulate plant-herbivore interactions by influencing nutritional traits (i.e. AM fungi-mediated nutrient uptake) and/or the secondary chemistry (i.e. endophytic alkaloids) of their host plant. Moreover, such grasses also accumulate large amounts of silicon (Si) from the soil, which can be deposited in tissues to act as a physical anti-herbivore defence. Recent evidence suggests that both endophytes and AM fungi independently facilitate Si uptake. However, the consequences of their interactions with piercing-sucking insects (i.e. aphids), or whether Si supply, endophytes, and AM fungi interact in this regard, are currently unknown. While Si deposition may be less effective against aphids than other herbivores (i.e. chewing caterpillars), Si supply can also alter plant secondary metabolite defences, which could affect sucking insects. In a factorial greenhouse experiment, we evaluated whether these components, acting alone or in combination, altered (1) foliar primary chemistry, (2) Si and symbiont-chemical (endophytic alkaloids) defences, as well as (3) performance of the bird cherry-oat aphid (Rhopalosiphum padi) feeding on tall fescue (Festuca arundinacea). Endophytes decreased all aphid performance parameters, including population growth and reproduction by 40%, but their impact was reversed by the presence of AM fungi, leading to a 52% increase in aphid performance compared with plants solely hosting endophytes. This improvement in performance was associated with reduced loline alkaloid levels and higher shoot nitrogen in AM-endophytic plants. Endophytes and AM fungi exhibited antagonism, with endophytes reducing AM colonization by 34% and AM presence decreasing endophyte loline alkaloids by 44%. While both fungi jointly increased Si accumulation by 39% under Si-supplied conditions, Si had no noticeable effects on aphids. Moreover, although Si supply had no identifiable effects on AM colonization, it reduced endophyte peramine alkaloids by 24%. Synthesis. Our findings indicate that symbiotic fungal partnerships and silicon provision may benefit plants but could weaken anti-herbivore defences when combined. Revealing the complex interactions among diverse fungal symbionts and showcasing their effects on different anti-herbivore defences (chemical and physical) and herbivore performance for the first time. © 2024 The Author(s). Journal of Ecology published by John Wiley & Sons Ltd on behalf of British Ecological Society
Efecto de herbicidas residuales aplicados en verano sobre diferentes especies sembradas en otoño en un argiudol típico de Uruguay. [abstract]
No full textRESUMEN.- La necesidad de manejar malezas resistentes a significado un aumento importante en el uso de herbicidas con persistencia en el suelo, con el consecuente riesgo para las especies susceptibles que siguen en la rotación. El objetivo de este trabajo ha sido el de evaluar el potencial daño de ocho herbicidas utilizados en soja y maíz sobre 6 especies sembradas en el otoño siguiente. -------- SUMMARY.- The need to manage herbicide-resistant weeds has led to a significant increase in the use of soil-persistent herbicides, posing a consequent risk to susceptible species in therotation. The objective of this study was to evaluate the potential damage of eight herbicides commonly used in soybean and corn crops on six species planted in the following autumn
Grazing intensity drives plant diversity but does not affect forage production in a natural grassland dominated by the tussock-forming grass Andropogon lateralis Nees.
No full textAbstract: Andropogon lateralis is a tall and highly plastic tussock-forming grass native from southern South America. It is a frequent component of Campos and Subtropical highland grasslands that often becomes dominant under lax grazing regimes. The aim of this work was to analyze the response of species diversity and forage production of a natural grassland dominated by A. lateralis to a wide range of grazing intensity. We hypothesized that species diversity and forage production would both peak at the intermediate canopy heights determined by grazing regimes of moderate intensity. A grazing experiment was conducted in a highland grassland with mesothermal humid climate at 922 masl (Atlantic Forest biome, Santa Catarina state, Brazil) that comprised 87 species from 20 families but had 50% of its standing biomass accounted by A. lateralis. Four pre-/post-grazing canopy heights?12/7, 20/12, 28/17, and 36/22 cm (measured on A. lateralis)?were arranged in a complete randomized block design with four replications, and intermittently stocked with beef heifers from October 2015 to October 2017. Andropogon lateralis cover decreased (from 75 to 50%), and species richness increased (15?25 species m?2) as canopy height decreased. Grazing intensity did not affect annual forage production (4.2 Mg DM ha?1). This natural grassland dominated by A. lateralis had a high capacity to adjust to grazing regimes of contrasting intensity, maintaining forage production stable over a wide range of canopy heights. However, to prevent losses in floristic diversity, such grassland should not be grazed at canopy heights higher than 28 c
El engramillamiento de los mejoramientos de campo: ¿afecta el carbono orgánico del suelo en el largo plazo?.
No full textEste artículo pone el foco en los cambios observados en el carbono orgánico del suelo bajo campo natural, al pasar a una situación de mejoramiento de campo con engramillamiento de largo plazo
Signal-sensing triggers the shutdown of HemKR, regulating heme and iron metabolism in the spirochete Leptospira biflexa.
No full textABSTRACT.- Heme and iron metabolic pathways are highly intertwined, both compounds being essential for key biological processes, yet becoming toxic if overabundant.Their concentrations are exquisitely regulated, including via dedicated two-component systems (TCSs) that sense signals and regulate adaptive responses.HemKR is a TCS present in both saprophytic and pathogenic Leptospira species, involved in the control of heme metabolism.However, the molecular means by which HemKR is switched on/off in a signal-dependent way, are still unknown.Moreover, a comprehensive list of HemKR-regulated genes, potentially overlapped with iron-responsive targets, is also missing. © 2024 Imelio et al
Coxiella burnetii y Neospora caninum como factores de riego para pérdidas gestacionales en un rodeo de cría. [Coxiella burnetii and Neospora caninum as risk factors for pregnancy losses in a beef cattle herd].
No full textRESUMEN.- Coxiella burnetii es una bacteria intracelular de gran trasmisibilidad, baja dosis infectiva y distribución mundial que produce la zoonosis Fiebre Q (coxielosis). En rumiantes produce trastornos reproductivos, incluidos abortos, retención de placenta, metritis e infertilidad. Se han realizado numerosos estudios sobre abortos en pequeños rumiantes y su prevalencia en el ganado, sin embargo, pocos estudios han explorado la asociación entre C. burnetii y las pérdidas reproductivas bovinas. ................. ABSTRACT.- Coxiella burnetii is a highly transmissible intracellular bacterium that causes Q fever, a notifiable zoonotic disease distributed worldwide. This bacterium can lead to reproductive disorders in ruminants, including abortion, retained placenta, metritis and infertility. Although numerous studies have been conducted on abortions in small ruminants and the prevalence in cattle, fewer studies have formally explored the association between C. burnetii and reproductive losses in cattle
Efecto de dos niveles de energía en la dieta durante el último tercio de gestación de vacas para carne sobre características de la placenta y la descendencia al nacimiento.[Effect of two energy levels in the diet during the last third of gestation of beef cows on characteristics of the placenta and offspring at birth].
No full textAbstract. The objective of the present study was to evaluate two energy intake levels during the last third of gestation of beef cows, placental characteristics, ethological and morphometric variables of their female calves were evaluated. Thirty-one British multiparous cows, inseminated at fixed time and carrying females were assigned on Day ?90 (Day 0=delivery) to two levels of energy intake until delivery: i- 125 % of the requirements (ALTA? n=15) and ii- 75 % of the requirements (BAJA? n=16). In the cows, live weight (PV), body condition score (CC),concentration of unesterified fatty acids (AGNE) and insulin were recorded. Placenta (weight, number of cotyledons and placental efficiency) was characterized and morphometric and behavioural measures were evaluated within the first 24 hours of calf life. At calving, BAJA cows had a higher concentration of AGNE (0.45 ± 0.03 vs 0.27 ± 0.03 mmol/L, P<0.01) and lower insulin (8.83 ± 0.73 vs 10.88 ± 0.71 µIU/mL, P<0.03), as well as lower PV (478 ± 15.4 vs 521 ± 11.8 kg, P<0.01) and CC (3.9 ± 0.08 vs 4.5 ± 0.06 u? P<0.01) compared to ALTA cows. The characteristics evaluated in the placentas were not affected by treatments, nor was the PV of the calves at birth. In the same way,none of the morphometric or behavioural variables were significantly affected by the treatments. In the present experiment, the undernourished cows mobilized body reserve during the last third of gestation to protect the integrity of their offspring? this was verified by the absence of differences in the parameters evaluated. Possibly, cows grazing native pastures develop mechanisms of accumulation and mobilization of body reserves that allow them, at least for the conditions of the present study, to overcome periods of forage shortage as an adaptation strategy.Resumen. El objetivo del presente trabajo fue evaluar dos niveles de energía en la dieta de vacas para carne durante el último tercio de gestación, sobre características de la placenta, variables etológicas y morfométricas de sus hijas. Treinta y una vacas británicas multíparas, inseminadas a tiempo fijo y gestando hembras fueron asignadas el Día ?90 (Día 0=parto) a dos niveles de consumo de energía relativo a los requerimientos de mantenimiento hasta el parto: i- 125 % (ALTO? n=15) y ii- 75 % (BAJO? n=16). En las vacas se registró peso vivo(PV), condición corporal (CC), concentración de ácidos grasos no esterificados (AGNE) e insulina. Se caracterizaronlas placentas (peso, número de cotiledones y eficiencia placentaria) y se evaluaron medidas morfométricas y comportamentales de las terneras en sus primeras 24 horas de vida. Al parto, las vacas de BAJO presentaron mayor concentración de AGNE (0.45 ± 0.03 vs 0.27 ± 0.03 mmol/L, P<0.01) y menor de insulina (8.83 ± 0.73 vs 10.88 ±0.71 µIU/mL, P<0.03), así como menor PV (478 ± 15.4 vs 521 ± 11.8 kg, P<0.01) y CC (3.9 ± 0.08 vs 4.5 ± 0.06 u? P<0.01) respecto a las vacas de ALTO. Las características evaluadas en las placentas no fueron afectadas por lostratamientos como tampoco lo fue el PV de las terneras al nacimiento. De la misma forma, ninguna de las variablesmorfométricas ni comportamentales fue afectada significativamente por los tratamientos. En el presente experimento, las vacas subalimentadas movilizaron reserva corporal durante el último tercio de gestación pararesguardar la integridad de sus crías verificado por la ausencia de diferencias en los parámetros evaluados. Posiblemente las vacas pastoreando campo nativo desarrollen mecanismos de acumulación y movilización de reservas corporales que les permite, al menos para las condiciones del presente estudio, sobreponerse a los períodos de escasez de forraje como estrategia de adaptación
Libro de Actas. [en línea]
No full textEl objetivo de este evento fue consolidar un espacio académico-técnico-político a nivel regional para la difusión e intercambio de conocimientos en torno a la restauración ecológica en el Bioma Pampa. ¿Por qué?, básicamente por dos motivos: (1) El Bioma Pampa (o Pastizales del Río de la Plata), endémico de Argentina, Brasil y Uruguay, conforma el mayor complejo de ecosistemas abiertos (pastizales, arbustales y sabanas) en América del Sur. Tiene un alto valor de conservación a nivel global, ya que los pastizales están dentro de los ecosistemas más amenazados y menos conservados del mundo. Se destaca su alta diversidad vegetal y nivel de endemismo (gramíneas en particular). Históricamente, la región ha sufrido una alta presión antrópica, en cada ciclo de expansión e intensificación agropecuaria, a lo que se ha sumado la forestación comercial y la invasión biológica de especies animales y vegetales. Esto ha degradado los ecosistemas (pastizales, bosques, humedales), reducido su biodiversidad y capacidad de brindar bienes y servicios ecosistémicos. (2) Los impactos ambientales derivados traspasan las fronteras nacionales, por lo cual, un enfoque regional sería el más adecuado para comprender y gestionar los procesos de degradación y desarrollar estrategias de conservación y restauración efectivas
Arroz 2023.
No full textLa Serie Técnica 267 resume información tecnológica y científica de los sistemas de producción de arroz, en el marco de un récord de rendimiento en un año de sequía extrema en todo el territorio nacional que provocó severos impactos en el sector agropecuario. La publicación reporta los resultados generados por los equipos de investigación del INIA y de otras instituciones en diversos proyectos conjuntos, para consulta y referencia de productores, profesionales y estudiantes. Durante 2023 se realizaron varias actividades de difusión en el Sistema Arroz-Ganadería. Por un lado, el tradicional taller de análisis tecnológico-productivo de la zafra, por otro lado, el seminario técnico sobre la sostenibilidad ambiental de los sistemas de producción de arroz, los días de campo de arroz y de la Unidad de Producción Arroz-Ganadería (UPAG) y, por último, la tradicional jornada anual de arroz, que se focalizó en las contingencias y previsiones para un probable año "Niño" 2023-2024. La Serie Técnica 267 refleja varios de los contenidos reportados en estas actividades