1,720,959 research outputs found
Estudios de evolución rápida en microorganismos bajo condiciones selectivas y de cambio global: algunos modelos y aplicaciones en biología
Get PDFTesis inédita de la Universidad Complutense de Madrid, Facultad de Veterinaria, Departamento de Producción Animal, leída el 05-06-2017.Los microorganismos son organismos modelo para el estudio de la evolución. Entender los procesos que operan modificando los microorganismos en el tiempo y como estos han transformado los organismos hasta la actualidad, pueden permitirnos abordar la problemática actual de pérdida de diversidad o ayudarnos a entender la complejidad de los organismos contemporáneos. Dentro de los trabajos enmarcados en esta tesis, hemos capitalizado la versatilidad de la evolución experimental como marco de investigación para abordar diferentes cuestiones adaptativas y evolutivas en microrganismos. Frente al desafío que representa la problemática del Cambio Global, hemos realizado diferentes experimentos de adaptación frente a estresantes antropogénicos (incremento de la temperatura, osmio, berilio y charcas minería de uranio) en el fitoplancton, a lo que se ha sumado un trabajo de revisión del estado actual del conocimiento. Las especies dentro del fitoplancton presentan una capacidad de adaptación diferencial, sin relación directa con el grupo taxonómico o el nicho ecológico. Los resultados obtenidos frente a presiones selectivas intensas, que implica una reducción drástica de la población, indican que la adaptación puede tener lugar gracias a mutantes presentes por azar dentro de las poblaciones naturales. Por tanto, en relación a los efectos del Cambio Global, la diversidad fitoplanctónica puede verse reducida, alterando la biogeografía futura de las poblaciones y favoreciendo a las especies con mayor plasticidad. Por otro lado, investigamos una transición evolutiva, como es el origen de la multicelularidad, bajo diferentes condiciones ecológicas. Por medio de una selección por sedimentación en S. cerevisiae, obtuvimos el fenotipo multicelular snowflake yeast a partir de su ancestro unicelular. La restricción nutricional no resultó limitante a la hora de obtener por selección fenotipo snowflake, ni implica una reversión hacia la unicelularidad a partir de un fenotipo snowflake. Sin embargo, la complejidad de las interacciones entre los organismos y su ambiente, pueden facilitar la persistencia de subpoblaciones (el fenotipo unicelular), así como la expansión de metapoblaciones (persistencia de poblaciones mixtas)...Globally, microorganisms play a key role in the maintenance of biogeochemical cycles and the status of ecosystems, particularly in aquatic environments where they act as primary producers. Microorganisms serve as model organisms for the study of evolution, they present an inherent importance due to its ecological role, ubiquity, its adaptive antecedents and preponderance throughout evolution. Understanding the processes that operate by modifying microorganisms over time and how they have modify living organisms until today, would enable as to tackle the current rate of loss of biological diversity or help us understand the complexity of contemporary organisms. Evolutionary processes can be address via experimental evolution, by means of controlled field or laboratory experiments. Evolution experiments make use of different organisms, often microorganisms, to examine evolutionary hypothesis, study adaptive processes and approach populations dynamics. Taking advantage of this methodology we can approach the issue of global change or to address evolutionary questions. Anthropogenic activities have reshaped and modified the ecosystems and the biosphere globally, becoming the current driving evolutionary force. In particular, is of primarily importance to study the effect of anthropogenic stressors in aquatic ecosystems. Phytoplankton is the base of the aquatic ecosystems, responsible of a significant amount of the atmospheric oxygen and plays an essential part in the “biological pump”, regenerating the atmospheric composition. Temperature increase and acidification, both in marine and freshwater environments, is a direct threaten to the aquatic ecosystems and indirectly to all the living forms on earth. Also the release of stressors, especially heavy metals, in aquatic environments result in a direct hazard to living forms, entailing a serious risk for the environments and human health. Phytoplankton is the base of the aquatic ecosystems, responsible of a significant amount of the atmospheric oxygen and plays an essential part in the “biological pump”, regenerating the atmospheric composition. Approaching this nowadays problem form the phytoplankton perspective is useful to address the problematic of anthropogenic...Depto. de Producción AnimalFac. de VeterinariaTRUEunpu
Microbial biominers: Sequential bioleaching and biouptake of metals from electronic scraps
No full textAuthor contributions: Camino García-Balboa: conceptualization (lead), data curation (equal), formal analysis (equal), investigation (equal), writing–original draft (supporting), writing–review and editing (equal). Paloma Martínez-Alesón: conceptualization (supporting), formal analysis (supporting), investigation (equal), writing–original draft (supporting), writing–review and editing (equal). Victoria López-Rodas: funding acquisition (lead), supervision (equal), writing–review and editing (equal). Eduardo Costas: funding acquisition (lead), supervision (equal), writing–review and editing (equal). Beatriz Baselga-Cervera: conceptualization (supporting), data curation (equal), formal analysis (equal), funding acquisition (supporting), visualization (lead), writing–original draft (lead), writing–review and editing (lead).Electronic scraps (e‐scraps) represent an attractive raw material to mine demandedmetals, as well as rare earth elements (REEs). A sequential microbial‐mediated pro-cess developed in two steps was examined to recover multiple elements. First, wemade use of an acidophilic bacteria consortium, mainly composed of Acidiphiliummultivorum and Leptospidillum ferriphilum, isolated from acid mine drainages. Theconsortium was inoculated in a dissolution of e‐scraps powder and cultured for15 days. Forty‐five elements were analyzed in the liquid phase over time, includingsilver, gold, and 15 REEs. The bioleaching efficiencies of the consortium were >99%for Cu, Co, Al, and Zn, 53% for Cd, and around 10% for Cr and Li on Day 7. Thesecond step consisted of a microalgae‐mediated uptake from e‐scraps leachate. Thestrains used were two acidophilic extremotolerant microalgae, Euglena sp. (EugVP)and Chlamydomonas sp. (ChlSG) strains, isolated from the same extreme environ-ment. Up to 7.3, 4.1, 1.3, and 0.7 µg by wet biomass (WB) of Zn, Al, Cu, and Mn,respectively, were uptaken by ChlSG biomass in 12 days, presenting higher effi-ciency than EugVP. Concerning REEs, ChlSG biouptake 14.9, 20.3, 13.7, 8.3 ng ofGd, Pr, Ce, La per WB. Meanwhile, EugVP captured 1.1, 1.5, 1.4, and 7.5, respec-tively. This paper shows the potential of a microbial sequential process to revalorizee‐scraps and recover metals and REEs, harnessing extremotolerant microorganismsFundación Alfonso Martín EscuderoDepto. de Producción AnimalFac. de VeterinariaTRUEpu
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Data from: Loss-of-heterozygosity facilitates a fitness valley crossing in experimentally evolved multicellular yeast
No full textThese data sets are generated to investigate a simple evolutionary landscape that arises from underdominance at a single locus where the fitness valley consists of only one less-fit genotype. We make use of an experimental system previous evolved in the laboratory, the Saccharomyces cerevisiae snowflake system. This system was experimentally selected resulting in a significant evolutionary shift, the transition from uni-to-multicellularity in asexual diploid populations. We carried out the phenotypic and fitness characterization of the strains. Additionally, we observed a rapid loss of heterozygosity (LOH) events in the heterozygote strains. Experimental evolution starting with the heterozygote strains suggests that LOH is common both under selection and without selection. LOH event drive adaptation that may enable rapid evolution in diploid yeast.Phenotyping data :
-Raw_data_sizing
-Raw_data_counts_and_total_cells_under_the_microscope
Fitness assays:
-Raw_data_TECAN
-Raw_data_fitness_by_CFUs
Experimental Evolution data:
-Raw_data__Settling_experiment_FlowCam_data_adter_10_passes
-Raw_data__Settling_experiment_plates_CFUsFunding provided by: Fundación Alfonso Martín EscuderoCrossref Funder Registry ID: http://dx.doi.org/10.13039/100008052Award Number: becas 2048Phenotypic characterization of the ancestral wildtype and constructed heterozygous and homozygous recessive strains was conducted in a Coulter Counter Multisizer 4 and FlowCam® 3.0. Replicate populations of different isolated strains were analyzed to obtain the population distributions. Fitness assays were carried out by measuring absorbance with Tecan ® infinite 200pro microplate reader, by Colony formation Units (CFUs) of single strains, and by means of competition assays by replica plating. Cells were also counted under an optic microscope in a Neubauer chamber. Populations during the evolution experiment were monitored by Colony formation Units and imaged with the FlowCam® at the end of the experiment, after 10 cycles of selection.
Data collected by:
-Beckman Coulter Counter Multisizer 4.
-Flow cytometer (FlowCam® 3.0 Fluid Imaging Technologies).
-Tecan ® infinite 200pro microplate reader growth curves data.
-Agar plating Colony formation Units (CFUs).
-Fitness assays were calculated with replica platting
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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