Tubulin-mediated anatomical and functional changes caused by Ca2+ in human erythrocytes

In previous research, we observed that tubulin can be found in three fractions within erythrocytes, i.e., attached to the membrane, as a soluble fraction, or as part of a structure that can be sedimented by centrifugation. Given that its differential distribution within these fractions may alter several hemorheological properties, such as erythrocyte deformability, the present work studied how this distribution is in turn affected by Ca2+, another key player in the regulation of erythrocyte cytoskeleton stability. The effect of Ca2+ on some hemorheological parameters was also assessed. The results showed that when Ca2+ concentrations increased in the cell, whether by the addition of ionophore A23187, by specific plasma membrane Ca2 + _ATPase (PMCA) inhibition, or due to arterial hypertension, tubulin translocate to the membrane, erythrocyte deformability decreased, and phosphatidylserine exposure increased. Moreover, increased Ca2+ was associated with an inverse correlation in the distribution of tubulin and spectrin, another important cytoskeleton protein. Based on these findings, we propose the existence of a mechanism of action through which higher Ca2+ concentrations in erythrocytes trigger the migration of tubulin to the membrane, a phenomenon that results in alterations of rheological and molecular aspects of the membrane itself, as well as of the integrity of the cytoskeleton. (AU)

New lipid-dependent Malassezia species from parrots / Nuevas especies lipodependientes del género Malassezia procedentes de loros

Background. All the currently recognized Malassezia species have been isolated from mammals. However, only a few of them have been isolated from birds. In fact, birds have been less frequently studied as carriers of Malassezia yeasts than mammals. Aim. In this study we describe two new taxa, Malassezia brasiliensis sp. nov. and Malassezia psittaci sp. nov. Methods. The isolates studied in this publication were isolated from pet parrots from Brazil. They were characterized using the current morphological and physiological identification scheme. DNA sequencing and analysis of the D1/D2 regions of the 26S rRNA gene, the ITS-5.8S rRNA gene sequences and the β-tubulin gene were also performed. Results. The strains proposed as new species did not completely fit the phenotypic profiles of any the described species. The validation of these new species was supported by analysis of the genes studied. The multilocus sequence analysis of the three loci provides robust support to delineate these species. Conclusions. These studies confirm the separation of these two new species from the other species of the genus Malassezia, as well as the presence of lipid-dependent Malassezia yeasts on parrots (AU)

Antecedentes. Todas las especies del género Malassezia actualmente identificadas se han aislado de mamíferos. Sin embargo, tan solo unas pocas de ellas se han aislado de aves. De hecho, las aves han sido estudiadas con menos frecuencia como portadoras de estas levaduras que los mamíferos. Objetivos. En este estudio describimos dos nuevas especies del género Malassezia: Malassezia brasiliensis sp. nov. y Malassezia psittaci sp. nov. Métodos. Las cepas estudiadas en esta publicación se aislaron de loros utilizados como animales de compañía en Brasil. Las cepas se caracterizaron mediante los criterios morfológicos y fisiológicos actualmente utilizados para la identificación de estas levaduras. También se llevó a cabo la secuenciación y el análisis de los fragmentos génicos D1/D2 26S e ITS-5.8S del ADN ribosómico y del gen de la β-tubulina. Resultados. Los perfiles fenotípicos de las cepas propuestas como nuevas especies no encajaron completamente con los de las especies descritas en este género. Además, el análisis de los genes estudiados respaldó la validez de las nuevas especies. El análisis multilocus de secuencias de los tres loci estudiados reforzó con mayor firmeza la definición de las nuevas especies. Conclusiones. Todos estos estudios confirman la separación de estas dos nuevas especies del resto de las especies descritas del género Malassezia, así como la existencia de especies dependientes de lípidos del género Malassezia en loros (AU)

Caracterización fisiológica y molecular de aislamientos de Phytophthora infestans de la región andina central colombiana / Physiological and molecular characterization of Phytophthora infestans isolates from the Central Colombian Andean Region

Antecedentes. El tizón tardío, causado por Phytophthora infestans, es una enfermedad devastadora de la papa y el tomate a nivel mundial, y en Colombia también ataca otros cultivos como la uchuva y el tomate de árbol. El conocimiento de la población del patógeno es determinante para el diseño efectivo de estrategias de control. Objetivos. Determinar las características fisiológicas y moleculares de aislamientos colombianos de P. infestans. Métodos. El nivel de resistencia al mefenoxam y al cimoxamil fue evaluado en aislamientos de Cundinamarca y Boyacá. Se estimó su virulencia y se determinó la producción y viabilidad de oosporas en diferentes sustratos con cruces entre aislamientos A1 y el aislamiento colombiano A2. Además, se determinó la diversidad molecular en el gen de avirulencia Avr3a, el gen de la β-tubulina y otros dos genes de copia única con motivo RXLR. Resultados. Los aislamientos colombianos tuvieron la posibilidad de reproducirse sexualmente. Encontramos todos los niveles de sensibilidad al mefenoxam, con el 48% de los aislamientos resistentes. Se detectó una diversidad de razas y a nivel genético la población fue clonal. Conclusiones. Estos resultados ayudarán a optimizar el uso de fungicidas y reducir la resistencia como estrategias de control, además de contribuir al conocimiento de la diversidad de este patógeno(AU)

Background. Late blight, caused by Phytophthora infestans, is one of the most devastating diseases found in potato and tomato crops worldwide. In Colombia it also attacks other important crops: cape gooseberry and tree tomato. The knowledge of the pathogen population is determinant to effectively design control strategies. Aims. To determine the physiological and molecular characteristics of a set of Colombian P. infestans isolates. Methods. Strains isolated from Cundinamarca and Boyacá were examined for the level of resistance to mefenoxam and cymoxanil. Virulence was tested for all strains and crosses between A1 mating type, from different hosts, and the Colombian A2 mating type were tested for the production and viability of oospores in different substrates. Additionally, the molecular diversity of the avirulence gene Avr3a, the β-tubulin gene, and two single copy genes showing RxLR motif, was assessed. Results. We found all levels of mefenoxam sensitivity, with 48% of the strains resistant. A high diversity of races was detected and the population was genetically clonal. Colombian strains had the possibility of sexual reproduction. Conclusions. These results will help in optimizing the use of fungicides and deployment of resistance as control strategies and will contribute to broader studies on diversity of this pathogen(AU)

Molecular phylogeny of asexual entomopathogenic fungi with special reference to Beauveria bassiana and Nomuraea rileyi

Basándose en el análisis de las secuencias de regiones parciales de los genes Beta-tubulina y ARN ribosómicosse estudió la filogenia, la taxonomía y las interrelaciones de importantes géneros de hongos entomopatógenosasexuales. Se estudio también la estructura de las especis Beauveria bassiana y Nomuraea rileyi. Seanalizó un total de 174 entradas fúngicas que representaban 94 especies. El análisis filogenético demostróque todas las especies de hongos entomopatogénicos asexuales incluidas en el estudio pertenecían a la familiaClavicipitaceae, del orden Hypocreales de los Ascomycota. Se observaron diferentes linajes dentro deB. bassiana, lo que demostró la complejidad de dicha especie. Algunos de los aislamientos de dicha especiedemostraron estar filogenéticamente más separados que determinados géneros morfológicos. Dentro de laespecie N. rileyi se pudo observar también la presencia de especiación críptica. Se concluye que los hongosasexuales entomopatogénicos han evolucionado de un linaje simple dentro de la familia Clavicipitaceae(AU)

The phylogenetic lineage, taxonomic affiliation and interrelationships of important asexualentomopathogenic fungal genera were studied using the sequences of partial regions of Beta-tubulin andrRNA genes. The species structures of Beauveria bassiana and Nomuraea rileyi were also investigated. Atotal of 147 fungal entries covering 94 species were analysed. Phylogenetic analysis placed all the asexualentomopathogenic fungal species analysed, in the family Clavicipitaceae of the order Hypocreales ofAscomycota. Deep phylogenetic lineages were observed in B. bassiana iterating the complex nature of thisspecies. Some of the isolates assigned to this species separated out more distinctly than morphologicallydistinguishable genera. Cryptic speciation was also evident in N. rileyi. It is concluded that the asexualfungi with entomopathogenic habit arose from a single lineage in sexual Clavicipitaceae(AU)

Pigment chemistry, taxonomy and phylogeny of the Hypoxyloideae (Xylariaceae)

The Hypoxyloideae (Xylariaceae with Nodulisporium-like anamorphs) were evaluated by a morphological and HPLC-based chemotaxonomic survey of more than 2000 specimens and cultures. Conspecificity of recent records with ancient type specimens were established in many cases by HPLC, since their characteristic metabolites may remain stable for over 200 years. Most constitute novel natural products that were identified in the course of concurrent "mycochemical" studies. A comparison of HPLC profiles considering relationships within the Hypoxyloideae as inferred from the biogenesis of these pigments agreed fairly with concurrent molecular phylogenetic studies, based on sequences of actin, beta-tubulin, and 5.8S/ITS nrDNA genes. Anamorphic morphology and secondary metabolism of cultures agreed well at generic level and above. A combination of chemical and morphological traits is favored over PCR-based approaches for species discrimination, if only relatively few taxa of these diverse genera have been sequenced. An overview on the chemical structures and biological activities of the characteristic metabolites is provided, their ecological importance is discussed, and the utility of chemotaxonomy to support and predict phylogenetic relationships in the Hypoxyloidae is demonstrated. A polythetic approach is most useful to elucidate the phylogeny of the Xylariaceae. Chemotaxonomy to assess fungal biodiversity has considerable utility(AU)

Therapeutic opportunities to control tumor cell cycles

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Tumor cell proliferation is frequently associated togenetic or epigenetic alterations in key cell cycleregulators. Most human tumors deregulate thispathway to sustain proliferation with independenceof external mitogenic factors. In addition, the alterationof cell cycle proteins may confer genomic instabilitythat results in additional mutations inthese tumor cells. The frequent alteration of the cellcycle in tumor cells has launched the identificationfor critical cell cycle regulators as anticancer targets.The inhibition of some cell cycle kinases suchas cyclin-dependent kinases (CDKs) or the Auroraand Polo mitotic kinases is currently under study inseveral preclinical and clinical trials. Similarly, theclinical success of microtubule poisons such as taxolhas promoted new applied research in mitosisregulation. Recent investigations have suggestednew targets of interest including additional kinases,phosphatases and other mitotic regulators such asmicrotubule motor proteins (kinesins). Currrent researchin this area will undoubtedly result in newand improved targeted therapies for cancer treatment