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Search Results: 1 - 10 of 283722 matches for " Maria C Montealegre "
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The hylEfm gene in pHylEfm of Enterococcus faecium is not required in pathogenesis of murine peritonitis
Diana Panesso, Maria C Montealegre, Sandra Rincón, Maria F Mojica, Louis B Rice, Kavindra V Singh, Barbara E Murray, Cesar A Arias
BMC Microbiology , 2011, DOI: 10.1186/1471-2180-11-20
Abstract: Five mutants of the hylEfm-region of pHylEfmTX16 from the sequenced endocarditis strain (TX16 [DO]) were obtained using an adaptation of the PheS* system and were evaluated in a commensal strain TX1330RF to which pHylEfmTX16 was transferred by mating; these include i) deletion of hylEfm only; ii) deletion of the gene downstream of hylEfm (down) of unknown function; iii) deletion of hylEfm plus down; iv) deletion of hylEfm-down and two adjacent genes; and v) a 7,534 bp deletion including these four genes plus partial deletion of two others, with replacement by cat. The 7,534 bp deletion did not affect virulence of TX16 in peritonitis but, when pHylEfmTX16Δ7,534 was transferred to the TX1330RF background, the transconjugant was affected in in vitro growth versus TX1330RF(pHylEfmTX16) and was attenuated in virulence; however, neither hylEfm nor hylEfm-down restored wild type function. We did not observe any in vivo effect on virulence of the other deletions of the hylEfm-regionThe four genes of the hylEfm region (including hylEfm) do not mediate the increased virulence conferred by pHylEfmTX16 in murine peritonitis. The use of the markerless counterselection system PheS* should facilitate the genetic manipulation of E. faecium in the future.Enterococcus faecium is a common enterococcal species increasingly isolated from hospital-associated infections in the USA [1]. Compelling evidence suggests that this substantial increase in E. faecium nosocomial infections is due to the worldwide occurrence of a genetic subcluster (designated clonal cluster 17, CC17) which encompasses clones that appear to have evolved independently [2-4]. Several genes have been associated with CC17 E. faecium including i) espEfm, encoding a surface protein which has been associated with increased biofilm formation and urinary tract infection (UTI) [4-6]; ii) some fms genes (two of which are also designated pilA and pilB), encoding putative microbial surface components recognizing adhesive matrix
Alternative Splicing and Subfunctionalization Generates Functional Diversity in Fungal Proteomes
Alexandra N. Marshall equal contributor,Maria Camila Montealegre equal contributor,Claudia Jiménez-López,Michael C. Lorenz,Ambro van Hoof
PLOS Genetics , 2013, DOI: 10.1371/journal.pgen.1003376
Abstract: Alternative splicing is commonly used by the Metazoa to generate more than one protein from a gene. However, such diversification of the proteome by alternative splicing is much rarer in fungi. We describe here an ancient fungal alternative splicing event in which these two proteins are generated from a single alternatively spliced ancestral SKI7/HBS1 gene retained in many species in both the Ascomycota and Basidiomycota. While the ability to express two proteins from a single SKI7/HBS1 gene is conserved in many fungi, the exact mechanism by which they achieve this varies. The alternative splicing was lost in Saccharomyces cerevisiae following the whole-genome duplication event as these two genes subfunctionalized into the present functionally distinct HBS1 and SKI7 genes. When expressed in yeast, the single gene from Lachancea kluyveri generates two functionally distinct proteins. Expression of one of these proteins complements hbs1, but not ski7 mutations, while the other protein complements ski7, but not hbs1. This is the first known case of subfunctionalization by loss of alternative splicing in yeast. By coincidence, the ancestral alternatively spliced gene was also duplicated in Schizosaccharomyces pombe with subsequent subfunctionalization and loss of splicing. Similar subfunctionalization by loss of alternative splicing in fungi also explains the presence of two PTC7 genes in the budding yeast Tetrapisispora blattae, suggesting that this is a common mechanism to preserve duplicate alternatively spliced genes.
Medicina darwiniana
Carlos de Céspedes Montealegre
Acta Médica Costarricense , 2009,
Abstract:
Genoma humano: perspectivas y realidades
Carlos de Céspedes Montealegre
Acta Médica Costarricense , 2000,
Abstract:
Celebración Darwin 2009
Carlos de Céspedes Montealegre
Acta Médica Costarricense , 2009,
Abstract:
La Facultad de Medicina de la Universidad de Costa Rica frente al nuevo milenio
Carlos de Céspedes Montealegre
Acta Médica Costarricense , 2000,
Abstract:
El enfoque evolucionario: el gran ausente en la medicina The evolutionary approach: the lost dimension of medicine
Carlos de Céspedes-Montealegre
Acta Médica Costarricense , 2013,
Abstract: Los resultados de un metanálisis sobre el uso de suplementos de calcio en mujeres, “sugieren fuertemente un riesgo relativamente modesto de infarto del miocardio y de accidentes vasculares cerebrales. Aunque los autores reconocen las limitaciones inherentes a este tipo de estudios, recomiendan “una reevaluación del rol de los suplementos de calcio en el manejo de la osteoporosis”. Como posibles mecanismos subyacentes se plantea un proceso de calcificación vascular regulado en forma similar a la osteogénesis y la posibilidad de que un exceso de calcio contribuya al riesgo de formación de trombos arteriales. El presente ensayo no pretende recomendar cambios en el uso clínico de los suplementos de calcio ni profundizar o ampliar en cuanto a los mecanismos mencionados y otros, sino tomar el problema como un ejemplo por analizar de acuerdo con los principios de la medicina darwiniana. Se debe tener en cuenta que el enfoque evolucionario trata de explicar la vulnerabilidad a la enfermedad del homo sapiens como especie. Aunque es indudable que existen susceptibilidades individuales a prácticamente todas las enfermedades, las expectativas del Proyecto del Genoma Humano -en cuanto a ejemplos y peso de genes predisponentes- con muy escasas excepciones, han estado lejos de cumplirse. Es razonable suponer que el interés por esta dimensión olvidada en la biomedicina -del todo ignorada en el artículo de marras- podría ayudar a entender mejor el origen de problemas médicos como este, e inclusive a orientar la investigación y aplicación de esa “medicina personalizada”. The results of a meta-analysis on the use of calcium supplements by women, “strongly suggest a relatively modest risk of myocardial infarction and stroke”. Although the authors acknowledge the inherent limitations in such studies, they recommend “a reassessment of the role of calcium supplements in the management of osteoporosis.” As possible underlying mechanisms, they suggest that a regulated vascular calcification process similar to osteogenesis occurs, and the possibility that excess calcium contributes to the risk of arterial thrombus formation. This essay is not intended to recommend changes in the clinical use of calcium supplements or to suggest a deeper analysis of the mentioned and other mechanisms. It seeks to analyze the problem according to the principles of Darwinian medicine. It is important to bear in mind that the evolutionary approach tries to explain the vulnerability to disease of Homo sapiens as a species. Although there is no doubt that individual susceptibilities to virtually all d
Minimal Lagrangian submanifolds in the complex hyperbolic space
I. Castro,C. R. Montealegre,F. Urbano
Mathematics , 2001,
Abstract: In this paper we construct new examples of minimal Lagrangian submanifolds in the complex hyperbolic space with large symmetry groups, obtaining three 1-parameter families with cohomegeneity one. We characterize them as the only minimal Lagrangian submanifolds in CH^n foliated by umbilical hypersurfaces of Lagrangian subspaces RH^n of CH^n. Several suitable generalizations of the above construction allow us to get new families of minimal Lagrangian submanifolds in CH^n from curves in CH^1 and (n-1)-dimensional minimal Lagrangian submanifolds of the complex space forms CP^n-1, CH^n-1 and C^n-1. Similar constructions are made in the complex projective space.
Derecho, fines y medios: la declinación del concurso de arquitectura
Montealegre,Alberto;
ARQ (Santiago) , 2007, DOI: 10.4067/S0717-69962007000300013
Abstract: the play of power that favors promoters over competitors in regulated competitions is ultimately part and parcel of an ideological context in which freedom is equated with market. the crisis of the neoliberal paradigm requires rethinking these conditions and encouraging a different context, in which the competition process takes on a new meaning, reducing existing asymmetries.
Derecho, fines y medios: la declinación del concurso de arquitectura
Alberto Montealegre
ARQ , 2007,
Abstract: El juego de poderes que favorece a los promotores sobre los concursantes en los concursos reglamentados responde, en definitiva, a un contexto ideológico en el que la libertad se identifica con el mercado. La crisis del paradigma neoliberal obliga a repensar esas condiciones y promover otro contexto donde la competencia adquiera un nuevo significado, reduciendo las asimetrías existentes. The play of power that favors promoters over competitors in regulated competitions is ultimately part and parcel of an ideological context in which freedom is equated with market. The crisis of the neoliberal paradigm requires rethinking these conditions and encouraging a different context, in which the competition process takes on a new meaning, reducing existing asymmetries.
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