Introduction of exogenous AMF species alters the biological diversity and functionality of AMF communities associated with cowpea

The salinity in arid and semi-arid areas of the world is rapidly expanding due to climate change and anthropogenic activities. The use of inoculants containing beneficial microbes (e.g. arbuscular mycorrhizal fungi (AMF) and rhizobia) is a promising alternative to improve plant production in these regions. Here, we investigated the effect of common agricultural practices such as the use of beneficial microbes as inoculum and crop rotation on cowpea growth and on its association with soil microbes under non- and salt-stressed conditions. Plant experiments were carried out using non-sterilized soil (supplemented or not with NaCl) under greenhouse conditions. Bradyrhizobium yuanmingense BR 3267 strain and a commercial mixture of AMF (Endoplant Riego) were used as inoculants. In parallel, we assessed cowpea growth following succession of buffelgrass (Cenchrus ciliaris) with or without prior soil disturbance. Plant and symbiotic parameters, nutrient content in leaves and AMF and root nodule communities through DNA metabarcoding were evaluated. Under non-stressed conditions, inoculation with AMF and/or BR 3267 strain led to significant increase of cowpea biomass production and higher N or P content in leaves. The imposed saline condition affected the cowpea growth although without significantly affecting the symbiotic parameters. Moreover, the increase of AMF propagules available in the soil at buffelgrass sowing through the inoculation of commercial AMF was a determining factor to mitigate the effects of soil tillage and salinity on cowpea growth. The bacterial communities in the root nodules were affected by AMF communities rather by rhizobia inoculation. Benefits of commercial AMF could be explained by changes in the biological and functionality of the AMF communities associated with cowpea. This study reveals that microbial inoculation and crop rotation are effective practices for improvement of cowpea growth and on mitigating the harmful effects of salt

Dupla inoculação (rizóbio e fungos micorrízicos arbusculares) mitigam efeitos nocivos da salinidade no crescimento do feijão-caupi

A salinidade em áreas áridas e semiáridas do mundo está a expandir rapidamente devido às alterações climáticas e atividades humanas. O uso de inóculos contendo microrganismos benéficos, como fungos micorrízicos arbusculares (FMA) e bactérias simbióticas fixadoras de azoto, aliado ao manejo adequado do solo e das culturas, é uma alternativa promissora para melhorar a produção vegetal nessas regiões. Aqui, investigámos o efeito de práticas agrícolas comuns, nomeadamente a utilização de microrganismos benéficos como inóculo e a perturbação do solo entre a rotação de culturas, no crescimento do feijão-caupi e na sua associação com micróbios do solo sob condições salinas e não salinas. A estirpe Bradyrhizobium yuanmingense BR 3267, e uma mistura comercial de FMA (Endoplant Riego) foram utilizados como inóculos. Paralelamente, avaliámos o crescimento do feijão-caupi, após sucessão ao capim-buffel com ou sem perturbação prévia do solo. Ensaios de plantas em solo não-esterilizado (suplementado ou não com NaCl) foram realizados em dois ciclos de 75 dias em estufa. Parâmetros vegetais e simbióticos e o teor de nutrientes nas folhas foram determinados, bem como a diversidade bacteriana e de FMA em raízes e nódulos de feijão-caupi por meio de sequenciamento DNA metabarcode. Os nossos dados revelaram que os parâmetros simbióticos (número de nódulos e/ou taxa de colonização) foram melhorados no feijão-caupi inoculado com Bradyrhizobium e/ou FMA comercial, o que consequentemente resultou em maior teor de N ou P nas folhas. A salinidade imposta afetou negativamente o crescimento do feijão, porém sem afetar significativamente os parâmetros simbióticos analisados. O aumento de propágulos de FMA disponíveis no solo através da inoculação de FMA comercial foi um fator determinante para mitigar os efeitos do manejo do solo no crescimento do feijão. A perturbação do solo mostrou impacto negativo nos parâmetros vegetais e simbióticos, exceto para o número de nódulos. Além disso, os efeitos positivos do uso de FMA comercial no crescimento do feijão-caupi, em condições controlo ou de salinidade podem ser explicados pelas mudanças na funcionalidade das comunidades de FMA associadas ao feijão-caupi. Por outro lado, as comunidades bacterianas em nódulos ou raízes do feijão não foram afetadas pela inoculação de FMA ou de rizóbios. Este estudo revela que a dupla inoculação (mistura de rizóbio e FMA) e a rotação de culturas, sem a perturbação do solo, são práticas eficazes para melhorar o crescimento do feijão-caupi e mitigar os efeitos nocivos do sal no seu crescimento. Mais, estes resultados também sugerem que os efeitos sinérgicos entre rizóbios e FMA dependem principalmente de um estabelecimento bem-sucedido da simbiose entre FMA e a planta hospedeira e não da comunidade de FMA em si

Evaluation of cytotoxicity, antimicrobial activity and physicochemical properties of a calcium aluminate-based endodontic material

A calcium aluminate-based endodontic material, EndoBinder, has been developed in order to reduce MTA negative characteristics, preserving its biological properties and clinical applications. OBJECTIVES: The aim of this study was to evaluate the cytotoxicity, antimicrobial activity, pH, solubility and water sorption of EndoBinder and to compare them with those of white MTA (WMTA). MATERIAL AND METHODS: Cytotoxicity was assessed through a multiparametric analysis employing 3T3 cells. Antimicrobial activity against Enterococcus faecalis (ATCC 29212), Staphylococcus aureus. (ATCC 25923) and Candida albicans (ATCC 10556) was determined by the agar diffusion method. pH was measured at periods of 3, 24, 72 and 168 hours. Solubility and water sorption evaluation were performed following ISO requirements. Data were statistically analyzed by ANOVA and Tukey`s test with a significance level of 5%. RESULTS: EndoBinder and WMTA were non-cytotoxic in all tested periods and with the different cell viability parameters. There was no statistical differences between both materials (P>.05). All tested materials were inhibitory by direct contact against all microbial strains tested. EndoBinder and WMTA presented alkaline pH in all tested times with higher values of pH for WMTA (P<.05). Both materials showed values complying with the solubility minimum requirements. However, EndoBinder showed lower solubility than WMTA (P<.05). No statistical differences were observed regarding water sorption (P>.05). CONCLUSION: Under these experimental conditions, we concluded that the calcium aluminate-based endodontic material EndoBinder demonstrated suitable biological and physicochemical properties, so it can be suggested as a material of choice in root resorption, perforations and root-end filling

Conference highlights of the 15th international conference on human retrovirology: HTLV and related retroviruses, 4-8 june 2011, Leuven, Gembloux, Belgium

The June 2011 15th International Conference on Human Retrovirology: HTLV and Related Viruses marks approximately 30 years since the discovery of HTLV-1. As anticipated, a large number of abstracts were submitted and presented by scientists, new and old to the field of retrovirology, from all five continents. The aim of this review is to distribute the scientific highlights of the presentations as analysed and represented by experts in specific fields of epidemiology, clinical research, immunology, animal models, molecular and cellular biology, and virology