Molecular genetics of naringenin biosynthesis, a typical plant secondary metabolite produced by Streptomyces clavuligerus

Background: Some types of flavonoid intermediates seemed to be restricted to plants. Naringenin is a typical plant metabolite, that has never been reported to be produced in prokariotes. Naringenin is formed by the action of a chalcone synthase using as starter 4-coumaroyl-CoA, which in dicotyledonous plants derives from phenylalanine by the action of a phenylalanine ammonia lyase. Results: A compound produced by Streptomyces clavuligerus has been identified by LC-MS and NMR as naringenin and coelutes in HPLC with a naringenin standard. Genome mining of S. clavuligerus revealed the presence of a gene for a chalcone synthase (ncs), side by side to a gene encoding a P450 cytochrome (ncyP) and separated from a gene encoding a Pal/Tal ammonia lyase (tal). Deletion of any of these genes results in naringenin non producer mutants. Complementation with the deleted gene restores naringenin production in the transformants. Furthermore, naringenin production increases in cultures supplemented with phenylalanine or tyrosine. Conclusion: This is the first time that naringenin is reported to be produced naturally in a prokariote. Interestingly three non-clustered genes are involved in naringenin production, which is unusual for secondary metabolites. A tentative pathway for naringenin biosynthesis has been proposedThis work was supported by Grant BIO2012-34723 from the Spanish Ministry of Economy and Competitivity. R. Álvarez-Álvarez received a FPU fellowship from the Spanish Ministry of Education, Culture and Sport

Comunidades de hongos endófitos en plantaciones de pino y robledales del norte de España

Replacement of native forest with plantations of other species can have important consequences over the ecosystem. Some of these changes have been widely studied, but very little information is available about what happen with fungal communities and specifically with endophyte species living there. In this work endophyte assemblages of pine plantations (Pinus sylvestris, P. nigra and P. pinaster) are compared with those found in the original oak forest (Quercus pyrenaica) of the study area (north of Palencia province, Spain). For this purpose, samples of needles/leaves and twigs from three trees in each one of the three plots sampled per host species, were first collected and later processed in the lab to detect all endophyte species living there. Besides an intensive data compilation was realized in the twelve sites studied to analyze the environmental, crown condition, dendrometric and soil variables involved in the distribution of the fungi. Endophyte assemblages of P. nigra and P. sylvestris resulted to be closer, and at the same time separated from the ones of P. pinaster and Q. pyrenaica. In addition, some variables were found to be related to the endophyte communities’ distribution. Finally, a change in the endophyte communities was detected due to the deterioration and replacement of native oak forests with pine plantations.La sustitución de los bosques autóctonos por plantaciones de otras especies puede tener importantes consecuencias sobre el ecosistema. Algunos de esos cambios ya han sido ampliamente estudiados, pero hasta el momento hay muy poca información acerca de lo que ocurre con las comunidades fúngicas y en especial con las de los endófitos que ahí viven. En este trabajo se analizaron las agrupaciones de endófitos existentes en las plantaciones de pino (Pinus sylvestris, P. nigra y P. pinaster) y bosques nativos de rebollo (Quercus pyrenaica) en el norte de la provincia de Palencia (España). Para ello se recogieron muestras de acículas/hojas y ramillos de cada una de las especies estudiadas que fueron procesadas en laboratorio para determinar qué especies de hongos endófitos portaban. Además se realizó una exhaustiva toma de datos en las doce parcelas estudiadas para analizar las variables ambientales, del estado fitosanitario de la copa, dendrométricas y edáficas implicadas en la distribución de los hongos. Las comunidades de endófitos encontradas en P. sylvestris y P. nigra resultaron ser similares entre sí, y al mismo tiempo diferentes de las de P. pinaster. Los endófitos aparecidos sobre Q. pyrenaica resultaron estar alejados de los del resto de los hospedantes, por lo que la conservación de los robledales es importante para evitar la pérdida de la diversidad fúngica. Finalmente se encontraron algunas variables ambientales relacionadas con la distribución de las comunidades de endófitos

Learning methodology based on weld virtual models in the mechanical engineering classroom

13 pp.Welding inspection activities within engineering degree programs are usable in practice. The competences acquired through these are usually contextualized in laboratory environments, using for its physical samples of welds, which used to be are scarce and expensive. In this study, a new methodology based on threedimensional macro‐photogrammetric models of welds is designed and actively implemented in the classroom, with students of mechanical engineering to evaluate different aspects about the suitability and learning performance of this novel methodology. To obtain the research conclusions, the activities have been chosen to evaluate four important aspects of it: usability, learning, motivation, and scalability. Results demonstrate that the adequate acceptation of the novel methodology studied, making possible new approaches for the acquisition of the competences related the welding inspection in the engineering education contextS