Factores que controlan la variabilidad morfológica de Pediastrum tetras bajo diferentes condiciones experimentales

Morphological variability and plasticity in phytoplankton populations are important for taxonomy, systematic, and evolutionary studies and are key characteristics for ecological plankton processes. The green algae Pediastrum tetras (Ehrenberg) Ralfs was studied to describe the variation in its population size structure and its response to changes in biotic (presence of Daphnia magna (Straus) and its info-chemicals) and abiotic factors (nutrient concentration). The results indicated that the nutrient supply could affect the coenobium population structure (diminishing the most common coenobium, the 8-celled one). D. magna significantly reduced P. tetras population density, because depredation affected it by significantly decreasing the biggest coenobium's density. In addition, info-chemicals induced a lower increase of the biggest coenobium when compared to the controls (rate of change was 45 % lower than in control cultures). Our study suggests that P. tetras coenobium size is subjected to a possible compromise (trade-off) in their natural environment: P. tetras population would tend to increase their size for a better use of nutrients and to decrease it when big herbivores are present.La plasticidad y variabilidad morfológica en poblaciones de fitoplancton son importantes para estudios de taxonomía, sistemática y evolución y son características clave para procesos ecológicos del plancton. Se ha estudiado el alga verde Pediastrum tetras (Ehrenberg) Ralfs para describir la variación en la estructura de tamaños de la población y su respuesta frente a factores bióticos (presencia de Daphnia magna (Straus) y sus info-químicos) y abióticos (concentración de nutrientes). Los resultados indicaron que el suministro de nutrientes podría afectar la estructura de los cenobios de la población (disminuyendo el cenobio más común, el de 8 células). D. magna redujo significativamente la densidad de la población de P. tetras ya que la depredación le afectaba disminuyendo significativamente la densidad de los cenobios más grandes. Además, los info-químicos indujeron un menor incremento de los cenobios más grandes comparados con el control (la tasa de cambio fue un 45 % menor que en los cultivos control). Nuestro estudio sugiere que el tamaño del cenobio de P. tetras está sometido a un posible compromiso (trade-off) en su medio natural: la población de P. tetras tendería a incrementar su tamaño para una mejor asimilación de los nutrientes y a disminuirlo cuando grandes herbívoros están presentes

Evolución del fitoplancton en el Parque Nacional de las Tablas de Daimiel (Ciudad Real, 1996-2002)

El Parque Nacional de Las Tablas de Daimiel (PNTD) es un humedal semiárido situado en la Llanura Manchega (Ciudad Real). En este artículo se expone la dinámica del fitoplancton desde 1996 hasta 2002, examinando las continuidades y divergencias que se observan en el espacio y el tiempo. Tres puntos del humedal (PG: entrada al Parque; MM y PN: salida en zona media y final) se muestrearon mensualmente desde Marzo 1996 a Diciembre 2002. El biovolumen total del fitoplancton del PNTD fue muy variable tanto en el tiempo como en el espacio, el valor mínimo y el máximo se presentaron en PG (0.06 mm3/l en mayo de 1996, y 775 mm3/l en septiembre de 2001). Se observa un marcado incremento del promedio de biovolumen de todo el humedal a lo largo del tiempo, de 11 ± 3 mm3/l en 1996 a 40 ± 9 mm3/l en 2002. La contribución relativa de los grupos taxonómicos al biovolumen total de fitoplancton mostró también cambios a corto y largo plazo, y fueron distintos en cada una de las tablas muestreadas. Hemos encontrado algunas especies de algas que son indicadoras de cierto grado de salinidad en el agua, ellas son: Chaetoceros muelleri, Urosolenia sp. y Katodinium fungiforme. Así como un aumento en el número de especies y densidad de las euglenofitas. Esta larga serie de datos nos permite extraer una serie de conclusiones sobre el funcionamiento de los productores primarios planctónicos en un humedal somero: a) a la escala espacial de todo el humedal el biovolumen de fitoplancton responde al clima local; b) la tendencia de eutrofización es claramente detectada en todo el humedal; c) las fluctuaciones hidrológicas provocan variaciones a corto plazo, permitiendo una serie continua de estados alternantes y no cíclicos de la comunidad; d) la heterogeneidad espacial de este sistema de islas y tablazos permite una amplia riqueza en el conjunto del humedal.Las Tablas de Daimiel National Park (TDNP) is a wetland located in La Mancha Plain (Ciudad Real, Central Spain). Our study reports 1996-2002 phytoplankton dynamics, examining spatio-temporal patterns of continuity and divergence. Three wetland sites (PG-main inlet, MM and PN-main outlets) were sampled monthly from March 1996 to December, 2002. Overall phytoplankton biovolume were very variable in space and time. Extreme values occurred in PG in May, 1996 (0.06 mm3/l) and September, 2001 (775 mm3/l). Average values of phytoplankton biovolume experienced aa marked increment over timefrom 11±3 mm3/l in 1996 () to 40±9 mm3/l in 2002. The relative contribution to the total biovolume of the taxonomic groups also showed short and long-term changes and they were different in each of the sampled sites. Some species indicating increasing salinity, such as Chaetoceros muelleri, Urosolenia sp. and Katodinium fungiforme, were recorded. Species numbers and density of euglenoids increased as well. This long-term dataset enabled us to draw some conclusions over planktonic primary producers functioning in a shallow wetland: a) at the wetland scale phytoplankton biovolum responds to local climate, b) a eutrophication trend is clearly detected in the whole wetland, c) hydrologic fluctuations are responsible for a short-term variability, thus allowing a variety of non-cyclic assemblage' s alternate states, d) spatial heterogeneity arising from the distribution of water tables and islands results in a remarkable species richness at the wetland scale

Influencia de la concentración de nutrientes y la herviboría sobre la estructura y la función de una comunidad algal

Un mismo conjunto de algas puede generar diferentes ensamblados finales estables en función del ambiente (lago, laguna, etc.) en que se desarrollen. En este trabajo se pretende averiguar qué mecanismos están afectando simultáneamente al conjunto de especies para que se produzca una selección de ellas apropiada a cada ambiente acuático, y cómo la variabilidad de la respuesta se ve reflejada en la estructura y función de la comunidad (biomasa total, fotosíntesis y respiración). Se ha ensayado la formación de una comunidad algal a partir de la disposición simultánea de 8 especies de algas cosmopolitas de agua dulce de morfología bien distinta (Cosmarium contractum, Cryptomonas ovata, Euglena gracilis, Limnothrix redekei, Monoraphidium contortum, Pediastrum tetras, Planktothrix agardhii y Scenedesmus acutus) en distintos tipos de medio de cultivo. Los tratamientos han sido cuatro: mayor y menor concentración de nutrientes (N y P) y presencia o no de Daphnia magna, Keratella cochlearis y Brachionus calicyflorus. Se han ensayado, además, sistemas de competencia entre algas y se ha averiguado la viabilidad de estas especies como inóculos tras un período de senescencia. La presencia de herbívoros (depredación) y la concentración de nutrientes (competencia), son los mecanismos que aislada o sin enérgicamente afectan al ensamblado de microalgas determinando diferentes estados alternativos desde un mismo conjunto de microalgas. Pero el efecto de estos mecanismos es a su vez diferente en función de las propiedades de las microalgas implicadas como son su tamaño, su tasa de crecimiento y la viabilidad de cada especie como inóculo. La presencia de herbívoros y la oligotrofia reducen la biomasa de productores primarios pero aumentan la diversidad relajando la competencia y aumentando la incertidumbre sobre el final alcanzado. Se demuestra además que las variaciones en la estructura de la comunidad se reflejan directamente en su función, afectando en última instancia a la producción primaria y la respiración.The same pool of algae can generate different final stable assemblages depending on the environment (lake, lagoon, etc.) where they develop. In this work we attempt to ascertain the mechanisms that simultaneously affect the species to appropriately select them for each aquatic environment, and how the variability in the response is reflected in the community structure and function (total biomass, photosynthesis and respiration). An algal community has been formed assembling 8 species of freshwater cosmopolite algae which have quite different morphologies (Cosmarium contractum, Cryptomonas ovata, Euglena gracilis, Limnothrix redekei, Monoraphidium contortum, Pediastrum tetras, Planktothrix agardhii and Scenedesmus acutus) using several kinds of culture media. The treatments were four: low and high nutrient concentrations (N and P) and presence and absence of Daphnia magna, Keratella cochlearis, and Brachionus calicyflorus. The competition between pairs of algae has been studied and also the viability of the species as inoculum after a senescence period. The presence of herbivores (predation) and the nutrient concentration (competition) are the mechanisms that by themselves or sinergically affect the microalgae assemblages originating different alternative states from the same pool of species. But the effect of these mechanisms is different depending on the algal properties such as size, growth rate, and viability as inoculum. The presence of herbivores and the oligotrophic conditions reduce the primary producers' biomass but increase diversity due to relaxation of competition and increase the uncertainty of final states. It is also shown that the variations in the community structure are directly reflected on the function, affecting primary production and respiration

Las Euglenófitas en las Tablas de Daimiel como ejemplo de las limitaciones de los indicadores biológicos de la degradación ambiental

Las Tablas de Daimiel National Park is a semiarid, hypertrophic wetland located in La Mancha (Ciudad Real, Central Spain). During the period 1996-2002 we carried out monthly samplings at three sites of Las Tablas. Thirty five taxa of Euglenophytes of the genera Astasia (1 taxon), Euglena (15), Lepocinclis (6), Phacus (9), and Trachelomonas (4) were identified. Six taxa are new records for Spain. Abundance, species richness, species groups and absolute and relative biomass of Euglenophytes widely fluctuated spatio-temporally in Las Tablas, without any statistically significant relationship (P > 0.05) with organic carbon (either particulate or dissolved), which has been long considered the main factor controlling the occurrence and abundance of Euglenophytes. The same lack of relationship was observed for other nutrients, such as ammonia, soluble reactive phosphorus and total nitrogen and phosphorus. Our results challenge the role of Euglenophytes for assessing environmental degradation in hypertrophic ecosystems, a topic of increasing interest in view of the newly implemented European Water Framework Directive and its proposals for biological monitoring. However, these results might invigorate ecological studies on Euglenophytes, still in its infancy unlike in other algal groups.El Parque Nacional Las Tablas de Daimiel es un humedal semiárido hipertrófico, situado en la llanura manchega (Ciudad Real). Entre 1996 y 2002 se realizaron muestreos mensuales en tres lugares representativos del Parque, en los que se identificaron 35 táxones diferentes de Euglenófitas: 1 del género Astasia, 15 de Euglena, 6 de Lepocinclis, 9 de Phacus y 4 de Trachelomonas, de los cuales 6 son citas nuevas para España. En este trabajo se ofrecen la descripción y una amplia iconografía de los mismos. Densidad, riqueza específica, grupos de especies y biovolúmenes absoluto y relativo fluctuaron mucho espacial y temporalmente en el humedal, sin manifestar relación alguna estadísticamente significativa (P > 0,05) con el carbono orgánico (tanto particulado como disuelto) presente en el agua, considerado desde antiguo como el principal factor que condiciona la presencia y la abundancia de las Euglenófitas, ni con otros nutrientes (amonio, ortofosfato, nitrógeno y fósforo totales). Estos resultados limitan en buena medida el uso de estos organismos como indicadores de la degradación ambiental en ecosistemas hipertróficos, de renovado interés por la puesta en marcha de la Directiva Europea del Agua, que contempla también la calidad biológica, y podrían contribuir a impulsar el estudio ecológico de las Euglenófitas, aún por desarrollar, a diferencia del de otros grupos de algas

Nigral and striatal connectivity alterations in asymptomatic LRRK2 mutation carriers: A magnetic resonance imaging study

Background. The study of the functional connectivity by means of magnetic resonance imaging (MRI) in asymptomatic LRRK2 mutation carriers could contribute to the characterization of the prediagnostic phase of LRRK2 associated Parkinson's disease (PD). Objective. To characterize MRI functional patterns during resting state in asymptomatic LRRK2 mutation carriers. Methods. We acquired structural and functional MRI data of 18 asymptomatic LRRK2 mutation carriers and 18 asymptomatic LRRK2 mutation noncarriers, all first-degree relatives of LRRK2-PD patients. Starting from resting state data, we analyzed the functional connectivity of the striatocortical and the nigrocortical circuitry. Structural brain data was analyzed by voxel based morphometry, cortical thickness and volumetric measures. Results: Asymptomatic LRRK2 mutation carriers had functional connectivity reductions between the caudal motor part of the left striatum and ipsilateral precuneus and superior parietal lobe. Connectivity in these regions correlated with subcortical gray matter volumes in mutation carriers. Asymptomatic carriers also showed increased connectivity between the right substantia nigra and bilateral occipital cortical regions (occipital pole and cuneus bilaterally, and right lateral occipital cortex). No intergroup differences in structural MRI measures were found. In LRRK2 mutation carriers, age and functional connectivity correlated negatively with striatal volumes. Additional analyses including only subjects with the G2019S mutation revealed similar findings. Conclusion: Asymptomatic LRRK2 mutation carriers showed functional connectivity changes in striatocortical and nigrocortical circuits compared with noncarriers. These findings support the concept that altered brain connectivity precedes the onset of classical motor features in a genetic form of PD

Advancing global health through development and clinical trials partnerships: a randomized, placebo-controlled, double-blind assessment of safety, tolerability, and Immunogenicity of Plasmodium falciparum sporozoites vaccine for malaria in healthy Equatoguinean men

Equatorial Guinea (EG) has implemented a successful malaria control program on Bioko Island. A highly effective vaccine would be an ideal complement to this effort and could lead to halting transmission and eliminating malaria. Sanaria® PfSPZ Vaccine (Plasmodium falciparum sporozoite Vaccine) is being developed for this purpose. To begin the process of establishing the efficacy of and implementing a PfSPZ Vaccine mass vaccination program in EG, we decided to conduct a series of clinical trials of PfSPZ Vaccine on Bioko Island. Because no clinical trial had ever been conducted in EG, we first successfully established the ethical, regulatory, quality, and clinical foundation for conducting trials. We now report the safety, tolerability, and immunogenicity results of the first clinical trial in the history of the country. Thirty adult males were randomized in the ratio 2:1 to receive three doses of 2.7 × 105 PfSPZ of PfSPZ Vaccine (N = 20) or normal saline placebo (N = 10) by direct venous inoculation at 8-week intervals. The vaccine was safe and well tolerated. Seventy percent, 65%, and 45% of vaccinees developed antibodies to Plasmodium falciparum (Pf) circumsporozoite protein (PfCSP) by enzyme-linked immunosorbent assay, PfSPZ by automated immunofluorescence assay, and PfSPZ by inhibition of sporozoite invasion assay, respectively. Antibody responses were significantly lower than responses in U.S. adults who received the same dosage regimen, but not significantly different than responses in young adult Malians. Based on these results, a clinical trial enrolling 135 subjects aged 6 months to 65 years has been initiated in EG; it includes PfSPZ Vaccine and first assessment in Africa of PfSPZ-CVac. ClinicalTrials.gov identifier: NCT02418962

Large scale multifactorial likelihood quantitative analysis of BRCA1 and BRCA2 variants: An ENIGMA resource to support clinical variant classification

The multifactorial likelihood analysis method has demonstrated utility for quantitative assessment of variant pathogenicity for multiple cancer syndrome genes. Independent data types currently incorporated in the model for assessing BRCA1 and BRCA2 variants include clinically calibrated prior probability of pathogenicity based on variant location and bioinformatic prediction of variant effect, co-segregation, family cancer history profile, co-occurrence with a pathogenic variant in the same gene, breast tumor pathology, and case-control information. Research and clinical data for multifactorial likelihood analysis were collated for 1,395 BRCA1/2 predominantly intronic and missense variants, enabling classification based on posterior probability of pathogenicity for 734 variants: 447 variants were classified as (likely) benign, and 94 as (likely) pathogenic; and 248 classifications were new or considerably altered relative to ClinVar submissions. Classifications were compared with information not yet included in the likelihood model, and evidence strengths aligned to those recommended for ACMG/AMP classification codes. Altered mRNA splicing or function relative to known nonpathogenic variant controls were moderately to strongly predictive of variant pathogenicity. Variant absence in population datasets provided supporting evidence for variant pathogenicity. These findings have direct relevance for BRCA1 and BRCA2 variant evaluation, and justify the need for gene-specific calibration of evidence types used for variant classification

Clonal chromosomal mosaicism and loss of chromosome Y in elderly men increase vulnerability for SARS-CoV-2

The pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2, COVID-19) had an estimated overall case fatality ratio of 1.38% (pre-vaccination), being 53% higher in males and increasing exponentially with age. Among 9578 individuals diagnosed with COVID-19 in the SCOURGE study, we found 133 cases (1.42%) with detectable clonal mosaicism for chromosome alterations (mCA) and 226 males (5.08%) with acquired loss of chromosome Y (LOY). Individuals with clonal mosaic events (mCA and/or LOY) showed a 54% increase in the risk of COVID-19 lethality. LOY is associated with transcriptomic biomarkers of immune dysfunction, pro-coagulation activity and cardiovascular risk. Interferon-induced genes involved in the initial immune response to SARS-CoV-2 are also down-regulated in LOY. Thus, mCA and LOY underlie at least part of the sex-biased severity and mortality of COVID-19 in aging patients. Given its potential therapeutic and prognostic relevance, evaluation of clonal mosaicism should be implemented as biomarker of COVID-19 severity in elderly people. Among 9578 individuals diagnosed with COVID-19 in the SCOURGE study, individuals with clonal mosaic events (clonal mosaicism for chromosome alterations and/or loss of chromosome Y) showed an increased risk of COVID-19 lethality