Heat-shock response in a yeast tps1 mutant deficient in trehalose synthesis

AbstractExponential cells of the Saccharomyces cerevisiae tps1 mutant underwent a rapid loss of viability upon a non-lethal heat exposure (from 28 to 42°C). However, a further more severe heat stress (52.5°C 5 min) induced an increase in the fraction of viable cells. This mutant can not synthesize trehalose either at 28° C or at 42°C due to the lack of a functional trehalose-6P synthase complex. In control experiments carried out with the wild-type W303-1 B, heat-stressed exponential phase cultures grown on YPgal at 28°C acquired thermotolerance to a higher extent than identical cultures grown on YPD, although in both cultures the level of stored trehalose was negligible. These data suggest that the bulk of trehalose accumulated in yeast upon mild heat treaments is not sufficient to account for the acquisition of thermotolerance

LOS MICROBIOS Y EL PREMIO NOBEL DE MEDICINA EN 1908 (EHRLICH Y MECHNIKOV).

Since its launch in 1901, the first designations of the Nobel Prize for Physiology or Medicine, have recognized essential advances in our understanding of the role of microscopic organisms as causative agents of infectious diseases. With the nomination of P. Ehrlich and I. Mechnikov in 1908, the Swedish Karolinska Institute extended this policy by distinguishing the outstanding research on the nature of the defensive responses mounted by the human body against aggressions triggered by microbes and foreign particles. These discoveries were the basis of a new discipline: Immunology.Desde su promulgación inicial en 1901, las primeras designaciones del denominado Premio Nobel en Fisiología o Medicina, reconocieron avances capitales en la función de los organismos microscópicos como agentes causales de las enfermedades infecciosas. Con la concesión a Paul Ehrlich e Ilya Mechnikov en 1908, el Instituto Karolinska de Suecia consolidó su propio criterio, galardonando la investigación trascendental sobre la naturaleza de las respuestas defensivas elaboradas por el cuerpo humano contra las agresiones provocadas por los microbios y las partículas extrañas. Estos descubrimientos constituyeron la base sobre la que ha emergido una nueva disciplina esencial: La Inmunología

Strong correlation between the antifungal effect of amphotericin B and its inhibitory action on germ-tube formation in a Candida albicans URA+ strain

The hypothetical capacity of amphotericin B to suppress the formation of germ-tubes, which is the first step of yeast-to-hypha conversion in Candida albicans, has been investigated in the wild-type strain CEY.1 (CAI.4-URA+). Exponential cells exposed to concentrations of amphotericin B below or around the MIC90, exhibited a weak reduction in the percentage of human serum-induced germ-tube formation at 37ºC compared with a non-exposed control. However, the dimorphic transition was drastically suppressed after addition of potentially lethal doses of amphotericin B, which also caused severe cell killing. In contrast, an identical experimental approach carried out with the fungistatic compound 5-fluorocytosine had no significant effect on the level of the germ-tube formation. Together, these results strongly point to a close correlation between the fungicidal action of amphotericin B and its ability to impair morphogenetic conversion in C. albicans. [Int Microbiol 2015; 18(1):25-31]Keywords: Candida albicans · amphotericin B · 5-fluorocytosine · germ-tube · cell killin

Critical examination of chemically modified hybrid thermosets: Synthesis, characterization and mechanical behavior in the plateau regime of polyaminosiloxane-nitrile-DGEBA

Poly(3-aminopropylmethylsiloxane) has been modified with acrylonitrile via aza Michael addition and a broad range of modified oligomers have been prepared with CN:NH₂ ratio ranging between 0.1 and 1. NMR and FTnIR analysis reveals that acrylonitrile modification proceeds without formation of tertiary amines. Modified oligomers have been characterized by DSC and analysis of Tg reveals that the adducts are self-associated probably due to weak hydrogen bonding and dipole interactions. The modified oligomers with a modification degree higher than 0.4 were miscible with DGEBA. The low and high temperature relaxations of the cured thermosets have been measured by DMTA. In addition to the commonly observed β₂ relaxation, a new β₁ process linked by an isosbestic point to β₂ has been found. β₁ is attributed to an extended segment comprising the pendant propionitrile group as well as the aminopropyl segment that connects tertiary amines to the polysiloxane backbone. Elastic modulus as well as the α relaxation can be tuned from high Tg and high rubbery modulus to low Tg and high damping thermosets changing the nitrile content. The experimental network structure obtained from elastic measurements and the Tg were related through well established structure-property relations.Authors wish to thank Spanish Ministerio de Economía y Competitividad for funding this work under grant MAT2010-17091

Respuesta del cultivo del melón (cucumis melo l.) a diferentes dosis y épocas de aplicación de nitrógeno en suelos de la región de Sevilla, Magdalena

el objetivo de la presente investigación es determinar la dosis y época crítica para la aplicación de nitrógeno en el cultivo del melón (Cucumis melo, L.) en suelos de la región de Sevilla, Magdalena