Diversidad del picoplancton eucariótico marino mediante métodos moleculares

Consultable des del TDXTítol obtingut de la portada digitalitzadaLos picoeucariontes que, junto con los procariontes heterotróficos y fototróficos, forman el picoplancton, pueden constituir una parte importante de la biomasa del mismo e incluso de todo el sistema. Su contribución a la producción primaria del ecosistema es también muy significativa. Pero hasta el momento la diversidad de la fracción eucariótica que forma la comunidad picoplanctónica marina era muy desconocida. La identificación de la fracción eucariótica del picoplancton en comunidades naturales es a menudo una tarea difícil, debido a su similar morfología y pequeño tamaño (< 5 mm). Algunos de ellos pueden ser discriminados a nivel de Clase mediante microscopía electrónica o cromatografía líquida de alta resolución (HPLC), pero en la mayoría de los casos no es posible hacer una identificación a más bajos niveles taxonómicos. Por otro lado, solo un pequeño porcentaje de estas especies picoplanctónicas puede crecer en cultivo, y además no hay garantía de que estos organismos aislados en cultivo sean los dominantes en la comunidad natural. La aproximación por técnicas moleculares basadas en análisis filogenéticos de secuencias de rRNA tales como la clonación y secuenciación, y técnicas de fingerprinting como la Denaturing Gradient Gel Electrophoresis (DGGE) o la Terminal Restriction Fragemnt Length Polymorphism (T-RFLP), han sido una alternativa que nos ha permitido caracterizar con más detalle la diversidad del picoplancton eucariótico en muestras naturales de diferentes sistemas marinos. Se ha muestreado una gran variedad de sistemas, desde mar abierto a zonas costeras, gracias a diferentes campañas oceanográficas: Mar de Weddel-Scotia (campaña DOVETAIL; Paso Drake (campaña DHARMA); Atlántico Norte (campaña ACSOE-NAE); Mar de Alborán (campaña MATER'97, 98 y 99). En ellas se obtuvieron muestras que abarcaban tanto la variabilidad espacial como la variabilidad temporal de las comunidades del picoplancton eucariótico marino. Gracias a la realización de bibliotecas genéticas de algunas de estas muestras (pertenecientes a la Antártida, al Mar de Alborán y al Atlántico Norte), mediante secuenciación y comparación con el banco de datos, se obtuvo información acerca de la diversidad de los grupos filogenéticos presentes en estos diferentes ambientes. Los resultados mostraron una elevada diversidad filogenética incluyendo muchos grupos taxónomicos diferentes y miembros de grupos filogenéticos distantes. La mayoría de estos grupos taxónomicos se afiliaban a organismos conocidos del picoplancton eucariótico fototrófico como las prasinofíceas, que fueron las más representadas, así como también las primnesiofíceas. Otra fracción, menos frecuente, pudo afiliarse a grupos claramente heterotróficos tales como ciliados, algunas crisofíceas, cercomonadales y hongos. Pero también apareció otro elevado número de secuencias distintas a cualquier secuencia conocida y que correspondían a nuevos linajes tales como los nuevos estramenópilos y los nuevos alveolados. Estos nuevos linajes aparecieron ampliamente distribuidos tanto filogenética como geográficamente. Algunos de ellos pueden constituir una fracción importante de los microorganismos heterotróficos y jugar un papel crucial en la red trófica microbiana. Técnicas de fingerprinting como la DGGE y la T-RFLP, fueron usadas para el estudio en paralelo de la diversidad de picoeucariontes en estas muestras marinas. Gracias a la optimización de la DGGE usando cebadores específicos para amplificar un fragmento del gen rRNA 18S de eucariontes, se pudo estudiar la diversidad y variabilidad a gran escala, de una manera detallada, de las comunidades del picoplancton eucariótico marino presentes en muestras de la Antártida y del Mar de Alborán. Esto nos permitió observar cambios en su distribución y composición no sólo a lo largo de gradientes verticales, sino en relación con escalas espaciales y temporales.Picoeukaryotes together with the heterotrophic and phototrophic prokaryotes, constitute the picoplankton. Picoeukaryotes can contribute an important part the picoplankton biomass and even to the total biomas of the system. Also, their contribution to the primary productivity of the ecosystem is very significant. However, very little is known about the diversity of the eukaryotic fraction of the marine picoplanktonic assemblages. The identification of picoeukaryotes in natural communities is difficult, principally due at their similar morphology and small size (< 5 mm). Some of them can be discriminated at the Class taxonomic level by electron microscopy or by HPLC pigment analyses, but most of them cannot be identified at lower taxonomic levels. Also, only a small percentage of the picoeukaryotes species grow in culture, and there is no guaranty that organisms currently available in pure culture are dominant in natural communities. The approximation with molecular techniques offers a promising alternative. The phylogenetic analyses of the rRNA sequences uses techniques such as cloning and sequencing, and/or fingerprinting techniques such as Denaturing Gradient Gel Electrophoresis (DGGE) and Terminal Restriction Fragment Length Polymorphism (T-RFLP). With these techniques I have characterized the diversity of eukaryotic picoplankton in natural samples from different marine systems. A wide variety of systems had been sampled from coast to open sea in different oceanographic cruises: Weddel-Scotia Sea (cruise DOVETAIL); Drake Passage (cruise DHARMA); North Atlantic Ocean (cruise ACSOE-NAE); Alborán Sea (cruises MATER'97, 98 y 99). Samples to study spatial and temporal variability of the marine eukaryotic picoplankton were obtained in all these cruises. Five genetic libraries were generated (two from the Southern Ocean, two from the North Atlantic Ocean and one from the Alborán Sea). By sequencing and comparison with the database I obtained information about the diversity of the phylogenetic groups present in the different marine systems. Results showed a high phylogenetic diversity. Most of these taxonomic groups were affiliated with known phototrophic picoeukaryotes such as prasinophytes (the most frequently represented) and prymnesiophytes. Other clones could be assigned to the heterotropic organisms such as ciliates, some crysophytes, cercomonads and fungi. But a significant number of sequences in the libraries did not show a close affiliation with any know class of organisms and formed two novel lineages: novel stramenopiles and novel alveolates. These novel lineages were abundant and widely distributed. Some of them may account for a large fraction of the heterotrophic microorganisms in the sea and could play an important role in the marine food webs. Fingerprinting techniques such as DGGE and T-RFLP were used to study de diversity of picoeukaryotes in these same samples. With the optimization of DGGE by using specific primers to amplify the 18S rRNA from eukaryotes we studied diversity and variability of the marine eukaryotic picoplankton assemblages present in samples from the Southern Ocean and the Alborán Sea. With these studies we obtained information about changes in their distribution and composition along the vertical gradient but also at larger spatial and temporal scales

Environmental DNA: A promising factor for tuberculosis risk assessment in multi-host settings

[EN] Attaining and maintaining the Official Tuberculosis Free status continues to be a challenge when several domestic and wild hosts contribute to the maintenance of the Mycobacterium tuberculosis complex (MTC). Local tuberculosis hotspots are sometimes identified in cattle in low-prevalence regions. We have, therefore, studied one such hotspot in depth in order to produce an epidemiological diagnosis. Host population size and MTC prevalence were estimated in selected wildlife and in livestock, while on-cattle environmental DNA detection was additionally used as a proxy for risk of exposure at the farm (herd) level. Positive skin test reactors were found on16 of the 24 cattle farms studied in the period 2012-2016. Although all goats tested negative to the skin test during this period, MTC was confirmed in four sheep at slaughter, thus indicating an unknown prevalence of infection in this host species. With regard to wildlife, the prevalence of MTC infection based on culture was 8.8% in the case of wild boar (Sus scrofa), and the only road-killed badger (Meles meles) submitted for culture tested positive. Two criteria were employed to divide the cattle farms into higher or lower risk: tuberculosis testing results and environmental DNA detection. Environmental MTC DNA detection yielded significant differences regarding "use of regional pastures" and "proximity to woodland". This study suggests that on-animal environmental DNA sampling may help when assessing contact risk as regards MTC in livestock at the herd level. This tool opens up new avenues of epidemiological research in complex multi-host settingsSIThis work was supported by the Programa de Tecnologı´as Avanzadas en Vigilancia Sanitaria (TAVS) from the Comunidad de Madrid (ref. S2013/ABI-2747). JMG holds a FPI predoctoral scholarship (BES-2015- 072206), funded by MINECO. This is a contribution to MINECO grant CGL2017-89866 WildDriver and EU-FEDER. This is also a contribution to Valle de Alcudia pilot project SG-2019-02 from PDR-CLM, and to GOSTU project EU-FEADER (AEIAGRI-PNDR-MAPA, ref. 20190020007521). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscrip

Colorectal cancer, sun exposure and dietary vitamin D and calcium intake in the MCC-Spain study

Objectives: To explore the association of colorectal cancer with environmental solar radiation and sun exposure behavior, considering phenotypic variables (eye color, hair color and skin phenotype), dietary intake of vitamin D and calcium, and socio-demographic factors. Study design: Multicenter population-based frequency matched case-control study in Spain (MCC-Spain), with 2140 CRC cases and 3950 controls. Methods: Data were obtained through personal interviews using a structured epidemiological questionnaire that included socio-demographic data, residential history, environmental exposures, behavior, phenotypic and dietary information. An environmental-lifetime sun exposure score was constructed combining residential history and average daily solar radiation, direct and diffuse. Logistic regression was used to explore the association between different variables. A structural equation model was used to verify the associations of the conceptual model. Results: We found a lower risk of CRC in subjects frequently exposed to sunlight during the previous summer and skin burning due to sun exposure. No association was observed in relation to the residential solar radiation scores. Subjects with light eye or light hair colors had a lower risk of CRC that those with darker colors. Dietary calcium and vitamin D were also protective factors, but not in the multivariate model. The structural equation model analysis suggested that higher sun exposure was associated with a decreased risk of CRC, as well as dietary intake of calcium and vitamin D, and these factors are correlated among themselves and with environmental solar radiation and skin phenotypes. Conclusion: The results agree with previous observations that sun exposure, dietary vitamin D and calcium intake, and serum 25(OH)D concentration reduce the risk of CRC and indicate that these factors may be relevant for cancer prevention

Evaluating the Potential of Polygenic Risk Score to Improve Colorectal Cancer Screening

Background: Colorectal cancer has high incidence and associ-ated mortality worldwide. Screening programs are recommended for men and women over 50. Intermediate screens such as fecal immunochemical testing (FIT) select patients for colonoscopy with suboptimal sensitivity. Additional biomarkers could improve the current scenario. Methods: We included 2,893 individuals with a positive FIT test. They were classified as cases when a high-risk lesion for colorectal cancer was detected after colonoscopy, whereas the control group comprised individuals with low-risk or no lesions. 65 colorectal cancer risk genetic variants were geno-typed. Polygenic risk score (PRS) and additive models for risk prediction incorporating sex, age, FIT value, and PRS were generated. Results: Risk score was higher in cases compared with controls [per allele OR = 1.04; 95% confidence interval (CI), 1.02-1.06; P = 65), compared with those in the first decile (<= 54; OR = 2.22; 95% CI, 1.59-3.12; P < 0.0001). The model combining sex, age, FIT value, and PRS reached the highest accuracy for identifying patients with a high-risk lesion [cross-validated area under the ROC curve (AUROC): 0.64; 95% CI, 0.62-0.66]. Conclusions: This is the first investigation analyzing PRS in a two-step colorectal cancer screening program. PRS could improve current colorectal cancer screening, most likely for higher at-risk subgroups. However, its capacity is limited to predict colorectal cancer risk status and should be complemented by additional biomarkers.Impact: PRS has capacity for risk stratification of colorectal cancer suggesting its potential for optimizing screening strategies alongside with other biomarkers

Formación en Nuevas Tecnologías e Intercambio de Experiencias Innovadoras en la Facultad de Geografía e Historia

Con este Proyecto de Innovación y Mejora de la Calidad Docente, de carácter institucional, se pretende dar continuidad a la etapa de innovación y formación docente que se inició el pasado Curso 2018-2019 en la Facultad de Geografía e Historia de la Universidad Complutense de Madrid. Así como a las anteriores iniciativas de la Facultad de Geografía e Historia en materia de nuevas tecnologías. El objetivo de este proyecto, siguiendo la metodología del año anterior, ha pretendido promover en nuestra Facultad una formación en el ámbito de la innovación educativa y de las nuevas tecnologías basada en: (i) la formación del Profesorado, del Personal de Administración y Servicios, y del Alumnado de nuestro Centro y (ii) en el intercambio de experiencias innovadoras entre representantes de estos colectivos, para poder hacer uso de las mismas en su desempeño docente, administrativo y formativo, respectivamente. El Proyecto, dirigido por el Vicedecano de Innovación, Nuevas Tecnologías y Comunicación de la Facultad, se adecua a las líneas prioritarias de la convocatoria Innova-Gestión Calidad, puesto que ha servido para profundizar en la innovación y en la mejora de la calidad docente-investigadora a través de programas formativos que, en la actualidad, constituyen objetivos prioritarios de la Estrategia UCM2020 de Investigación

Elaboración de listas de verificación para la realización, tutorización y evaluación de Trabajos Fin de Grado

Memoria ID-10 Ayudas de la Universidad de Salamanca para la innovación docente, curso 2020-2021

Space and time in the tectonic evolution of the northwestern Iberian Massif: Implications for the Variscan belt.

Recent advances in geochemical studies of igneous rocks, isotopic age data for magmatism and metamorphism, quantitative pressure-temperature (P-T) estimates of metamorphic evolution, and structural geology in the northwestern Iberian Massif are integrated into a synthesis of the tectonic evolution that places the autochthonous and allochthonous terranes in the framework of Paleozoic plate tectonics. Because northwestern Iberia is free from strike-slip faults of continental scale, it is retrodeformable and preserves valuable information about the orthogonal component of convergence of Gondwana with Laurentia and/or Baltica, and the opening and closure of the Rheic Ocean. The evolution deduced for northwest Iberia is extended to the rest of the Variscan belt in an attempt to develop a three-dimensional interpretation that assigns great importance to the transcurrent components of convergence. Dominant Carboniferous dextral transpression following large Devonian and Early Carboniferous thrusting and recumbent folding is invoked to explain the complexity of the belt without requiring a large number of peri-Gondwanan terranes, and its ophiolites and highpressure allochthonous units are related to a single oceanic closure. Palinspastic reconstruction of the Variscan massifs and zones cannot be achieved without restoration of terrane transport along the colliding plate margins. A schematic reconstruction is proposed that involves postcollisional strike-slip displacement of ~3000 km between Laurussia and Gondwana during the Carboniferous

Aula itinerante de Patrimonio Cultural II

Memoria final del PIMCD UCM 2020/2021 número 31

Herramientas de aprendizaje para estudiantes de secundaria: Aplicación de la Genética a una situación real

Depto. de Genética, Fisiología y MicrobiologíaFac. de Ciencias BiológicasFALSEsubmitte