Estructura, biogénesis y dependencia nutritiva de los esclerocios de Paxillus ammoniavirescens (Boletales, Paxillaceae)

The objective of this work was to study the structure, composition, and biogenesis of Paxillus ammoniavirescens sclerotia, as well as their possible use as inoculum for birch mycorrhizae. By means of histochemical stains, a change of the composition and internal organization of these structures during their maturation was observed. The formation of sclerotia begins with a clustering of hyphae that gives rise to a structure with pseudoparenchyma in the central part; these immature sclerotia develop to form, at maturity, a pseudoparenchymatic outer cortex of 6 or 7 layers of hyphae around an inner medulla. The hyphae of mature sclerotia have a large number of protein bodies in contrast to scarce lipid accumulations. The formation of sclerotia is influenced by the characteristics of the culture medium and the temperature. The greatest number of sclerotia was obtained by reducing the concentration of the diammonium phosphate to 0.94 mM in the MMN medium, and maintaining the cultures at 8 °C for 2 weeks. Finally it was shown that the sclerotia of this species can be used directly as inoculum, both to generate mycelium in the culture media and to initiate mycorrhizae in birch plants in vitro.El objetivo de este trabajo ha sido estudiar la estructura, composición y biogénesis de los esclerocios de Paxillus ammoniavirescens, así como su posible utilización como inóculo en la micorrización de abedul. Por medio de tinciones histoquímicas se ha observado un cambio de la composición y organización interna de estas estructuras durante su maduración. La formación del esclerocio se inicia con un agrupamiento de hifas que da lugar a una estructura con pseudoparénquima en la parte central; estos esclerocios inmaduros se desarrollan hasta que, en la madurez, se forma una corteza externa pseudoparenquimática de 6 o 7 capas de hifas y una médula en su interior. Las hifas de los esclerocios maduros presentan una gran cantidad de cuerpos proteicos, en contraste con escasos acúmulos lipídicos. La formación de esclerocios está influenciada por las características del medio de cultivo y la temperatura. El mayor número de esclerocios se obtuvo reduciendo la concentración del fosfato diamónico a 0,94 mM en el medio MMN y manteniendo los cultivos a 8 °C durante 2 semanas. Finalmente se ha demostrado que los esclerocios de esta especie pueden ser utilizados directamente como inóculo, tanto para generar micelio en los medios de cultivo como para micorrizar in vitro plantas de abedul

Estructura, biogénesis y dependencia nutritiva de los esclerocios de Paxillus ammoniavirescens (Boletales, Paxillaceae) = Structure, biogenesis and nutricional dependence of Paxillus ammoniavirescens sclerotia (Boletales, Paxillaceae)

The objective of this work was to study the structure, composition, and biogenesis of Paxillus ammoniavirescens sclerotia, as well as their possible use as inoculum for birch mycorrhizae. By means of histochemical stains, a change of the composition and internal organization of these structures during their maturation was observed. The formation of sclerotia begins with a clustering of hyphae that gives rise to a structure with pseudoparenchyma in the central part; these immature sclerotia develop to form, at maturity, a pseudoparenchymatic outer cortex of 6 or 7 layers of hyphae around an inner medulla. The hyphae of mature sclerotia have a large number of protein bodies in contrast to scarce lipid accumulations. The formation of sclerotia is influenced by the characteristics of the culture medium and the temperature. The greatest number of sclerotia was obtained by reducing the concentration of the diammonium phosphate to 0.94 mM in the MMN medium, and maintaining the cultures at 8 °C for 2 weeks. Finally it was shown that the sclerotia of this species can be used directly as inoculum, both to generate mycelium in the culture media and to initiate mycorrhizae in birch plants in vitro

The effect of temperature and water stress on laboratory germination of Eucalyptus globulus Labill. seeds of different sizes

Germination rate and germination capacity of Eucalyptus globulus Labill. increased significantly with increasing temperature (13o to 33 oC) for all seed sizes to an optimum at 28 oC, then decreased. Biggest seeds generally germinated best at all temperatures. Germination was also very sensitive to water potential (0 to $-0.75$ MPa), with no germination occuring at potentials below $-0.25$ MPa.Effet de la température et du stress hydrique sur la germination en laboratoire de graines d'Eucalyptus globulus Labill de différentes tailles. On a étudié l'influence sur la germination des graines d'Eucalyptus globulus Labill de températures constantes comprises entre 13o et 33 oC et de potentiels hydriques compris entre 0 et $-0,75$ MPa. La germination était significativement influencée par la température et la taille des graines. La vitesse et le taux de germination augmentaient avec la température pour atteindre un optimum à 28 oC et ensuite diminuaient. Quand la germination était effectuée en conditions de stress on observait une diminution du taux de germination entre $-0,01$ et $-0,75$ MPa. Plus aucune graine ne germait à $-0,25$ MPa et au-delà

Influencia de las condiciones culturales en el crecimiento de diferentes hongos ectomicorricicos

Se estudió la capacidad de crecimiento de 12 especies de hongos ectomicorrícicos en cuatro medios de cultivo (MMN, MFM, BAF y MEPA) que difieren considerablemente en contenido mineral, fuentes de carbono y vitaminas. Los resultados obtenidos permiten determinar la existencia de diferencias significativas en el crecimiento de diferentes especies de hongos ectomicorrícicos en cultivo puro

Risk of thrombosis according to need of phlebotomies in patients with polycythemia vera treated with hydroxyurea.

Hematocrit control below 45% is associated with a lower rate of thrombosis in polycythemia vera. In patients receiving hydroxyurea, this target can be achieved with hydroxyurea alone or with the combination of hydroxyurea plus phlebotomies. However, the clinical implications of phlebotomy requirement under hydroxyurea therapy are unknown. The aim of this study was to evaluate the need for additional phlebotomies during the first five years of hydroxyurea therapy in 533 patients with polycythemia vera. Patients requiring 3 or more phlebotomies per year (n=85, 16%) showed a worse hematocrit control than those requiring 2 or less phlebotomies per year (n=448, 84%). There were no significant differences between the two study groups regarding leukocyte and platelet counts. Patients requiring 3 or more phlebotomies per year received significantly higher doses of hydroxyurea than the remaining patients. A significant higher rate of thrombosis was found in patients treated with hydroxyurea plus 3 or more phlebotomies per year compared to hydroxyurea with 0-2 phlebotomies per year (20.5% vs. 5.3% at 3 years; P<0.0001). In multivariate analysis, independent risk factors for thrombosis were phlebotomy dependency (HR: 3.3, 95%CI: 1.5-6.9; P=0.002) and thrombosis at diagnosis (HR: 4.7, 95%CI: 2.3-9.8; P<0.0001). The proportion of patients fulfilling the European LeukemiaNet criteria of resistance/intolerance to hydroxyurea was significantly higher in the group requiring 3 or more phlebotomies per year (18.7% vs. 7.1%; P=0.001) mainly due to extrahematologic toxicity. In conclusion, phlebotomy requirement under hydroxyurea therapy identifies a subset of patients with increased proliferation of polycythemia vera and higher risk of thrombosis.This work was supported by a grant from the Instituto de Salud Carlos III, Spanish Health Ministry, PI13/00557, PI1300393. The GEMFIN received a grant from Novartis for the development of the Spanish Registry of Polycythemia Vera and for conducting the present project