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Search Results: 1 - 10 of 23758 matches for " Fernando Baquero "
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Evolution and the nature of time
Baquero,Fernando;
International Microbiology , 2005,
Abstract: the concept of time is critical in evolutionary thought, but rarely has it been considered as an object of theoretical research by evolutionary biologists. evolution is an organism's possibility of access to the future; in other words, evolutionary reward is paid out as increased time. replicating entities are granted time, but for them, time only serves to allow replication and evolution, and to further expand the frontier of time. the present review discusses the possible influence of considering time not as a pure dimension (or an a priori intuitive condition of human experience) but as an object in itself. at least as a metaphor, time can be considered as a self-replicating entity rooted in physical (including biological) beings, with the result of producing dimensional time. time self-replication forces beings to replicate, which, in turn, further sustains the replication of time. in that sense, time-replication may constitute the driving force, i.e., the basic engine, providing directional energy to the evolutionary process. the philosophical roots, caveats, and perspectives of this hypothesis are presented here. the metaphor of replicating-time plays with the possibility of viewing time not as a merely regulatory component of scientific inquiry but instead, as a real and creative constituent of nature and, for this reason, an object worthy of research in the natural sciences.
Eukaryotic microorganisms in cold environments: examples from Pyrenean glaciers
Fernando Baquero,Cristina Cid
Frontiers in Microbiology , 2013, DOI: 10.3389/fmicb.2013.00055
Abstract: Little is known about the viability of eukaryotic microorganisms preserved in icy regions. Here we report on the diversity of microbial eukaryotes in ice samples derived from four Pyrenean glaciers. The species composition of eukaryotic communities in these glaciers is unknown mostly because of the presence of a multi-year ice cap, and it is not clear whether they harbor the same populations. The recent deglaciation of these areas is allowing an easy access to glacial layers that correspond to the “Little Ice Age” although some isolated deposits are attributed to previous glacial cycles. In this study, we use molecular 18S rRNA-based approaches to characterize some of the microbial eukaryotic populations associated with Pyrenean glaciers. Firstly, we performed a chemical and microscopical characterization of ice samples. Secondly, molecular analyses revealed interesting protist genetic diversity in glaciers. In order to understand the microbial composition of the ice samples the eukaryotic communities resident in the glacial samples were examined by amplifying community DNA and constructing clone libraries with 18S rRNA primers. After removal of potential chimeric sequences and dereplication of identical sequences, phylogenetic analysis demonstrated that several different protists could be identified. Protist diversity was more phylum rich in Aneto and Monte Perdido glaciers. The dominant taxonomic groups across all samples (>1% of all sequences) were Viridiplantae and Rhizaria. Significant variations in relative abundances of protist phyla between higher and lower glaciers were observed. At the genus level, significant differences were also recorded for the dominant genera Chloromonas, Raphidonema, Heteromita, Koliella, and Bodomorpha. In addition, protist community structure showed significant differences between glaciers. The relative abundances of protist groups at different taxonomic levels correlated with the altitude and area of glaciers and with pH of ice, but little or no relationships to other chemical characteristics were found.
Intelligibility in microbial complex systems: Wittgenstein and the score of life
Fernando Baquero,Andrés Moya
Frontiers in Cellular and Infection Microbiology , 2012, DOI: 10.3389/fcimb.2012.00088
Abstract: Knowledge in microbiology is reaching an extreme level of diversification and complexity, which paradoxically results in a strong reduction in the intelligibility of microbial life. In our days, the “score of life” metaphor is more accurate to express the complexity of living systems than the classic “book of life.” Music and life can be represented at lower hierarchical levels by music scores and genomic sequences, and such representations have a generational influence in the reproduction of music and life. If music can be considered as a representation of life, such representation remains as unthinkable as life itself. The analysis of scores and genomic sequences might provide mechanistic, phylogenetic, and evolutionary insights into music and life, but not about their real dynamics and nature, which is still maintained unthinkable, as was proposed by Wittgenstein. As complex systems, life or music is composed by thinkable and only showable parts, and a strategy of half-thinking, half-seeing is needed to expand knowledge. Complex models for complex systems, based on experiences on trans-hierarchical integrations, should be developed in order to provide a mixture of legibility and imageability of biological processes, which should lead to higher levels of intelligibility of microbial life.
Criterios para la determinación del número de cucharas en una turbina Pelton
Jaramillo Valencia Octavio,Baquero Herrera José Fernando
Ingeniería e Investigación , 1985,
Abstract: Los criterios descritos en el presente artículo se aplican en los programas de computador del proyecto de grado "Comportamiento Hidráulico de Cucharas Pelton", calificado con la distinción de meritorio, en el cual a partir de la altura neta, el caudal y la velocidad angular, se determina la geometria de las cucharas. Forma parte del programa de investigación que la Facultad de Ingeniería está llevando a cabo con el propósito de desarrollar turbinas Pelton de baja potencia con la financiación de Colciencias y bajo la dirección del Ingeniero Alvaro Rey Romero.
Bacterias con alta tasa de mutación: los riesgos de una vida acelerada
GALáN,JUAN CARLOS; BAQUERO,MARíA ROSARIO; MOROSINI,MARíA ISABEL; BAQUERO,FERNANDO;
Infectio , 2006,
Abstract: the potential of producing genetic variability, either by mutation or by recombination, is the driving force of evolution in a living organism. genetic variability is a quite regulated process in which bacteria tend to maintain a low mutation rate. however, a variable proportion of bacteria with a higher mutation rate than that of the modal is always present in any population. moreover, a direct relationship exists between the proportion of mutator strains and environmental stress. in chronic infectious diseases, due to prolonged antibiotic regimens, nearly 50% of the population may be represented by mutating bacteria. such a positive selection is due to the capacity of this type of strains to develop antibiotic resistance (100 fold higher than normal bacteria) this trait has been used as an accelerated evolution model to predict the ease of certain resistant variants to emerge as well as to infer which targets are more prone to be modified and the concomitant cost that such variability would imply to the organism. the microbiology laboratory might then do an effort to detect mutating strains before the appearance of resistance mechanisms that may lead to therapeutic failures.
Bacterias con alta tasa de mutación: los riesgos de una vida acelerada High mutation rate bacteria: Risks of a high-speed life
JUAN CARLOS GALáN,MARíA ROSARIO BAQUERO,MARíA ISABEL MOROSINI,FERNANDO BAQUERO
Infectio , 2006,
Abstract: El proceso evolutivo de un ser vivo se acelera cuanto mayor sea su capacidad para producir variabilidad genética, bien por mutación, bien por recombinación. Sin embargo, cuanto mayor sea esta capacidad, mayor también será el riesgo de acumular mutaciones del etéreas. La variabilidad genética es, por tanto, un proceso altamente regulado, de tal manera que las bacterias tienden a mantener una baja tasa de mutación. En diferentes poblaciones bacterianas analizadas hay siempre un porcentaje variable de cepas con una tasa de mutación superior a la frecuencia modal del resto de la población. Existe una relación directa entre la proporción de cepas que mutan y el grado de estrés del ambiente. Así, en los procesos infecciosos crónicos, en los que el tratamiento antibiótico es constante durante períodos prolongados, se observan los mayores porcentajes de bacterias que mutan, cercano al 50% de la población. Esta selección positiva de bacterias que mutan es debida al enorme potencial que presentan para desarrollar resistencia antibiótica (100 veces superior a una bacteria normal). Esta capacidad ha sido explotada, en algunos centros de investigación, como un modelo natural de evolución acelerada para predecir la facilidad con la que determinadas variantes resistentes pueden aparecer, saber qué posiciones serán las más susceptibles a los cambios y cuál será el costo para la bacteria. El laboratorio de microbiología debe hacer un esfuerzo por detectar estas cepas mutadoras antes de que desarrollen mecanismos de resistencia e induzcan el fracaso terapéutico. The potential of producing genetic variability, either by mutation or by recombination, is the driving force of evolution in a living organism. Genetic variability is a quite regulated process in which bacteria tend to maintain a low mutation rate. However, a variable proportion of bacteria with a higher mutation rate than that of the modal is always present in any population. Moreover, a direct relationship exists between the proportion of mutator strains and environmental stress. In chronic infectious diseases, due to prolonged antibiotic regimens, nearly 50% of the population may be represented by mutating bacteria. Such a positive selection is due to the capacity of this type of strains to develop antibiotic resistance (100 fold higher than normal bacteria) This trait has been used as an accelerated evolution model to predict the ease of certain resistant variants to emerge as well as to infer which targets are more prone to be modified and the concomitant cost that such variability would imply to the organis
Effect of an Oxadiazoline and a Lignan on Mycolic Acid Biosynthesis and Ultrastructural Changes of Mycobacterium tuberculosis
Eduard Baquero,Wiston Qui?ones,Wellman Ribon,Maria Leonor Caldas,Ladys Sarmiento,Fernando Echeverri
Tuberculosis Research and Treatment , 2011, DOI: 10.1155/2011/986409
Abstract: Tuberculosis (TB) is an important disease that causes thousands of deaths around the world. Resistance against antitubercular available drugs has been reported; so, research on new effective antimycobacterial molecules is needed. Antimycobacterial activity of three lignans and two synthetic hydrazones was assessed against Mycobacterium tuberculosis H37Rv by antimycobacterial microdilution assay (TEMA). An oxadiazoline (AC451) and a lignan (ethoxycubebin) were the most active compounds (MIC 6.09 and 62.4?μM, resp.). Several changes in mycolic acid profile of treated bacteria were detected with both compounds by mass spectrometry analysis. Additionally, the level of reduction of mycolic acids in ethoxycubebin treatment was correlated to disruption in bacterial morphology. 1. Introduction Approximately 33% of the human population is infected with Mycobacterium tuberculosis, and every day 4,200 people die of tuberculosis around the world. Several facts have been considered as main factors for pandemic progress [1]. Antituberculosis drugs were discovered more than 40 years ago, [2, 3] resistant strains have emerged due to lengthy treatments, and latent and persistent infections have spread all over the world as population migration has increased. In addition and as it has been described recently, “HIV/AIDS continues to fuel tuberculosis epidemic, especially in Africa” [4]. Under these circumstances, there is an urgent need to search for new antimycobacterial substances to be used as templates for drug development so that the current situation of the disease can be tackled. Moreover, studies on the mechanism of action of new molecules can be useful to design more effective antimycobacterial compounds. Species of Mycobacterium and related genus synthesize mycolic acids (MAs), which are important lipid components of the cell wall (CW), are related to the protection of M. tuberculosis against dehydration, chemical injury, host immune system, and entry of hydrophilic antibiotics [5]. Therefore, MAs metabolism is an important target for Mycobacterium growth inhibition, for example, isoniazid is a first line antitubercular drug that inhibits MAs biosynthesis [6]. In this paper, we report the antimycobacterial activity of three lignans and two oxadiazoline derivatives against M. tuberculosis H37Rv analyzed by mass spectrometry and transmission electronic microscopy to assess the effect of the most active molecules on MAs biosynthesis and the ultrastructural changes of this pathogen. 2. Materials and Methods 2.1. Plant Material and Compounds Leaves of Virola flexuosa
Mitochondrial dysfunction in Trypanosoma cruzi: the role of Serratia marcescens prodigiosin in the alternative treatment of Chagas disease
Carlos Genes, Eduard Baquero, Fernando Echeverri, Juan D Maya, Omar Triana
Parasites & Vectors , 2011, DOI: 10.1186/1756-3305-4-66
Abstract: Parasites exposed to prodigiosin altered the mitochondrial function and oxidative phosphorylation could not have a normal course, probably by inhibition of complex III. Prodigiosin did not produce cytotoxic effects in lymphocytes and Vero cells and has better effects than benznidazole. Our data suggest that the action of prodigiosin on the parasites is mediated by mitochondrial structural and functional disruptions that could lead the parasites to an apoptotic-like cell death process.Here, we propose a potentially useful trypanocidal agent derived from knowledge of an important aspect of the natural life cycle of the parasite: the vector-parasite interaction. Our results indicate that prodigiosin could be a good candidate for the treatment of Chagas disease.Chagas disease continues to represent a health threat for an estimated 28 million people, most of them living in Latin America. One of the most important problems in the outcome of Chagas disease is the limitation of existing drugs for treatment [1]. For more than 40 years, only two drugs, nifurtimox and benznidazole, have been available to treat Chagas disease. Both have limited efficacy (about 80% efficacy in the acute phase and lower in the chronic phase), as well as frequent and significant side effects [2]. Other potentially beneficial drugs, such as allopurinol or itraconazole, do not have a high enough degree of clinical efficacy, as compared with nifurtimox or benznidazole; Posaconazole is a promising drug, but expensive [2]. Furthermore, hundreds of natural and synthetic compounds have been tested against the protozoan parasite Trypanosoma cruzi, the causative agent of Chagas disease. However, very few are devoid of cytotoxic activity or have proved more efficacious than nifurtimox and benznidazole, especially against the intracellular amastigotes [3]. Therefore, disease control is mainly based on the elimination of insect vectors. Most species of the Triatominae (Hemiptera-Reduviidae) subfamily are pote
A New Method to prepare an e,e,e Trisadduct of C60 Using a Protection-Deprotection Sequence
Duarte-Ruiz, álvaro;Echegoyen, Luis;Aya, Adriana;Gómez-Baquero, Fernando;
Journal of the Mexican Chemical Society , 2009,
Abstract: a racemic mixture of the e,e,e bingel-trisadduct, tris[di(ethoxycarbonyl)methano][60]fullerene 3 was synthesized by malonate additions (bingel reaction) following by retro diels-alder reactions using a c60 tris-e,e,e adduct of anthracene 1 as precursor. using this approach, the anthracenes act as protective groups and help orient the new additions so that poly-adducts with particular geometries are obtained. from the e,e,e anthracene-trisadduct 1 we also obtained the mono[di(ethoxycarbonyl)methano][60]fullerene 6 and bis [di(ethoxycarbonyl)methano][60]fullerene 7. this approach exhibits a total yield of 4,2 % for the e,e,e tris malonate adduct, gives rise to less complex reaction mixtures and makes it easier to separate and characterize the compounds than other methods. the compounds obtained where characterized by uv/vis, ft-ir, 1h nmr, and maldi-tof.
Síntesis de un compuesto de polimetacrilato de metilo con nanotubos de carbono de pared múltiple a escala de laboratorio
Méndez,Yuly; Zú?iga,Camilo; Gómez-Baquero,Fernando; Duarte Ruiz,álvaro;
Revista de Ingeniería , 2009,
Abstract: the purpose of the current work was the lab-scale synthesis and thermal characterization of a poly(methyl methacrylate)-multi-walled carbon nanotube (pmmamwnts) composite. the pmma-mwnts composite was produced by mass in-situ polymerization, using benzoyl peroxide (bpo) as initiator. as a previous step to the polymerization, a bpo-mwnts reaction was performed to trigger the formation of free radicals in the surface of the mwnts. the mwnt concentration in the composite was varied to produce samples of 0%, 0.1% and 0.5% w/w of mwnts in pmma. the produced composites show an adequate dispersion and different thermal properties than the pmma blank, suggesting a property transfer from the nanoparticles. the proposed production method is simple, of relatively low cost and easily applicable in a variety of industrial applications.
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