RESUMEN
Class 1 integrase intI1 has been considered as a good proxy for anthropogenic pollution because of being linked to genes conferring resistance to antibiotics. The gene cassettes of class 1 integrons could carry diverse antibiotic resistance genes (ARGs) and conduct horizontal gene transfer among microorganisms. The present study applied high-throughput sequencing technique combined with an intI1 database and genome assembly to quantify the abundance of intI1 in 64 environmental samples from 8 ecosystems, and to investigate the diverse arrangements of ARG-carrying gene cassettes (ACGCs) carried by class 1 integrons. The abundance of detected intI1 ranged from 3.83 × 10-4 to 4.26 × 10° intI1/cell. High correlation (Pearson's r = 0.852) between intI1 and ARG abundance indicated that intI1 could be considered as an important indicator of ARGs in environments. Aminoglycoside resistance genes were most frequently observed on gene cassettes, carried by 57% assembled ACGCs, followed by trimethoprim and beta-lactam resistance genes. This study established the pipeline for broad monitoring of intI1 in various environmental samples and scanning the ARGs carried by integrons. These findings supplemented our knowledge on the distribution of class 1 integrons and ARGs carried on mobile genetic elements, benefiting future studies on horizontal gene transfer of ARGs.
Asunto(s)
Antibacterianos , Farmacorresistencia Microbiana/genética , Integrones , Bacterias/genética , Ambiente , Monitoreo del Ambiente , Humanos , PrevalenciaRESUMEN
Sexual reproduction of heterothallic clavicipitaceous fungus Villosiclava virens (anamorph: Ustilaginoidea virens) generates ascospores, which is considered as primary infection source of rice false smut disease. However, little is known about the molecular underpinnings of sexual reproduction in V. virens. In this study, transcriptomes of V. virens in fruiting body (FB) and sporulating mycelia (SM) were compared using Illumina paired-end sequencing technology. A total of 33,384,588 and 23,765,275 clean reads of FB and SM transcriptome profiles could be used to map cDNA of V. virens, respectively. We evaluated the gene expression variations between FB and SM, a total of 488 genes therein were significantly higher expressed in FB than SM, and 342 genes were significantly higher expressed genes in SM than FB. These differentially expressed genes were annotated using Kyoto Encyclopedia of Genes and Genomes and Gene Ontology databases. Several genes were found to specifically function in sexual reproduction, involving in mating type, pheromone synthesis, signaling transduction, transcription factors, and meiosis; additionally, a few of genes were presumed to function in conidia sporulation and infection. Comparative transcriptome analysis of V. virens during FB and SM provided an overview of gene expression profiles at the transcriptional level and provided hints to better understand the molecular mechanisms of sexual development. Additionally, the data presented here also proved benefit for mining of essential genes contributing to sexual conidiation and infection.
Asunto(s)
Ascomicetos/fisiología , Cuerpos Fructíferos de los Hongos , Perfilación de la Expresión Génica , Regulación Fúngica de la Expresión Génica , Genes Fúngicos , Micelio , Transcriptoma , Biología Computacional , Ontología de Genes , Secuenciación de Nucleótidos de Alto Rendimiento , Anotación de Secuencia MolecularRESUMEN
Ascospores of Villosiclava virens are a primary infection source of rice false smut. This phytopathogenic fungus exists in heterothallic form, and mating compatibility is regulated by mating-type locus 1 (MAT1). However, the MAT1 locus structure remains unknown. The MAT1-1 and MAT1-2 idiomorphs of V. virens were characterized and annotated on the basis of cDNA sequencing. A multiplex polymerase chain reaction (PCR) method was developed to identify the mating types of hyphae and sclerotia. The MAT1-1 locus of V. virens contains three mating-type genes: MAT1-1-1, MAT1-1-2 and MAT1-1-3, and a pseudogene similar to MAT1-2-1. The MAT1-2 locus harbors the MAT1-2-1 gene and a new mating-type gene MAT1-2-8. The mRNA of MAT1-1-1, MAT1-1-3 and MAT1-2-1, but not MAT1-1-2, was detectible by reverse transcription PCR in vegetative mycelia. However, the mRNA of MAT1-1-2 was detectible in the stroma, which is a sexual reproduction structure of V. virens. A multiplex PCR detection method was developed for the identification of the MAT1-1 and MAT1-2 idiomorphs. All 20 wild-type strains harbored either the MAT1-1 or MAT1-2 idiomorphs. Sclerotia that harbored both the MAT1-1 and MAT1-2 idiomorphs had potential to form fertile stromata, whereas those that harbored only the MAT1-1 idiomorph could not form mature stromata.
Asunto(s)
Genes del Tipo Sexual de los Hongos , Sitios Genéticos , Hypocreales/genética , Oryza/microbiología , Hypocreales/fisiología , Reacción en Cadena de la Polimerasa , Reproducción , Alineación de Secuencia , Análisis de Secuencia de ADN , Esporas Fúngicas/genética , Esporas Fúngicas/fisiología , Ustilaginales/genéticaRESUMEN
The herbicide isoproturon is widely used for controlling weed/grass in agricultural practice. However, the side effect of isoproturon as contaminants on crops is unknown. In this study, we investigated isoproturon-induced oxidative stress in wheat ( Triticum aestivum). The plants were grown in soils with isoproturon at 0-20 mg/kg and showed negative biological responses. The growth of wheat seedlings with isoproturon was inhibited. Chlorophyll content significantly decreased at the low concentration of isoproturon (2 mg/kg), suggesting that chlorophyll was rather sensitive to isoproturon exposure. The level of thiobarbituric acid reactive substances (TBARS), an indicator of cellular peroxidation, showed an increase, indicating oxidative damage to plants. The isoproturon-induced oxidative stress resulted in a substantial change in activities of the majority of antioxidant enzymes, including superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX). Activities of the antioxidant enzymes showed a general increase at low isoproturon concentrations and a decrease at high isoproturon concentrations. Activities of CAT in leaves showed progressive suppression under the isoproturon exposure. Analysis of nondenaturing polyacrylamide gel electrophoresis (PAGE) confirmed these results. We also tested the activity of glutathione S-transferase (GST) and observed the activity stimulated by isoproturon at 2-10 mg/kg.
Asunto(s)
Herbicidas/farmacología , Compuestos de Fenilurea/farmacología , Triticum/efectos de los fármacos , Triticum/crecimiento & desarrollo , Antioxidantes/análisis , Catalasa/antagonistas & inhibidores , Catalasa/metabolismo , Clorofila/análisis , Estrés Oxidativo , Peroxidasa/antagonistas & inhibidores , Peroxidasa/metabolismo , Plantones/química , Plantones/efectos de los fármacos , Plantones/crecimiento & desarrollo , Superóxido Dismutasa/antagonistas & inhibidores , Superóxido Dismutasa/metabolismo , Sustancias Reactivas al Ácido Tiobarbitúrico/análisis , Triticum/químicaRESUMEN
Chlorotoluron is a phenylurea herbicide that is widely used for controlling grass weeds in the land of cereal, cotton and fruit production. However, extensive use of this herbicide may lead to its accumulation in ecosystems, thus inducing the toxicity to crops and vegetables. To assess chlorotoluron-induced toxicity in plants, we performed the experiment focusing on the metabolic adaptation of wheat plants (Triticum aestivum) to the chlorotoluron-induced oxidative stress. The wheat plants were cultured in the soils with chlorotoluron at concentrations of 0-25mg/kg. Chlorotoluron accumulation in plants was positively correlated with the external chlorotoluron concentrations, but negatively with the plant growth. Treatment with chlorotoluron induced the accumulation of O(2)(-) and H(2)O(2) in leaves and resulted in the peroxidation of plasma membrane lipids in the plant. We measured the endogenous proline level and found that it accumulated significantly in chlorotoluron-exposed roots and leaves. To understand the biochemical responses to the herbicide, activities of the antioxidant enzymes, such as superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX) were assayed. Analysis of SOD activity by non-denaturing polyacrylamide gel electrophoresis (PAGE) revealed that there were three isoforms in the roots and leaves, but the isoforms in the tissues showed different patterns. Also, using the native PAGE, 6 isoforms of root POD and 10 in leaves were detected. The total activity of POD in roots was significantly enhanced. Activities of APX in roots and leaves showed a similar pattern. The CAT activities were generally suppressed under the chlorotoluron exposure.