The Annual Cycle of Nutrients and Phytoplankton Dynamics in a Shallow Monomictic Lake in Scotland (Loch Rusky)

Loch Rusky showed monomictic characteristics, with thermal stratification occurring through the summer. Dissolved oxygen was depleted in the hypolimnion in the late summer but remained near saturation levels through the seasons of water mixing. Changes in the nutrient concentrations in the water (such as nitrate, phosphate and silicate) were related to phytoplankton community changes (e. g. Diatom spring increase), external supply (e.g. nitrate, sulphate, chloride, COD) and dissolved oxygen levels (e.g. phosphate). The seasonal phytoplankton community started to increase its biomass in April, reaching a single summer peak in July and later a small autumnal peak before falling to lower population numbers after November. The spring community was dominatted by diatoms such as Asterionella formosa and Melosira italica , the summer by Cryptomanadales such as cryptomonas ovata and Rhodomonas minuta var nanoplanctica which attained a very rapid maximum in biomass in mid-summer and by colonial Cyanobacteria in the autumn. The primary production was correlated with the phytoplankton standing crop only in early spring, showing small peaks in mid-summer and winter months. An analysis of variance in the method on the routine Carbon-14 method showed fairly low variance for the whole method although, cell rupture during filtration particularly affecting nanoplankton, could mask the production results in summer. The diversity calculated by the Shannon-Weaver index was strongly influenced by the relative abundance of few species. The maximum phytoplankton diversity was registered in winter. The seasonal succession pattern of the zooplankton population was dominated by Rotifera such as Keratella cochlearis and Polyarthra remata and the copepod Diaptomus qracilis which occurred mainly in the epilimnion during summer. Cladocera was insignif icantly represented in the zooplankton. Some degree of trophic relationship was observed between nannoflagellates and rotifers seasonal populations

Seroprevalencia al virus adipogénico Adenovirus-36 y su asociación con la obesidad y la concentración sérica de colesterol en adultos del noreste de México: estudio piloto

Propósito y método del estudio: El virus Adenovirus-36 (Ad-36) induce adipogénesis en modelos animales, aumenta la acumulación de lípidos en adipocitos y disminuye la concentración sérica de colesterol, siendo considerado como posible factor de riesgo para desarrollar obesidad. La seroprevalencia al Ad-36 se ha reportado hasta en el 30% en adultos con obesidad en diferentes partes del mundo. En México no se ha establecido si existe asociación entre la seroprevalencia al Ad-36 y la obesidad en adultos. Objetivo: Determinar la seroprevalencia al Ad-36 y su asociación con la obesidad y la concentración sérica de colesterol en adultos del Noreste de México. Material y Método: Estudio aprobado por el Comité de Investigación, Ética y Bioseguridad de la Facultad de Salud Pública y Nutrición y registrado como 17- FaSPyN-SA-09.TP. Se reclutó de septiembre 2017 a marzo 2018 a 263 voluntarios de 18-70 años de edad, residentes del Noreste de México quienes firmaron el consentimiento informado. Se evaluó el estado nutricio utilizando medidas antropométricas (peso, estatura, circunferencia de cintura y cadera), se calcularon índices asociados a la obesidad y se midió el % de grasa corporal por absorciometría dual de rayos X (Lunar iDxa). Se realizó venopunción, se almacenó el suero a -80°C, hasta su uso para determinar la seropositividad de anticuerpos contra Ad-36 utilizando un método inmunoenzimático (ELISA) y se evaluó el colesterol sérico utilizando el método colesterol oxidasa-peroxidasa. El análisis de los datos se realizó con el software SPSS versión 21.0 Contribuciones y conclusiones: De acuerdo al índice de masa corporal (IMC), el 44.6% corresponde al grupo de peso normal, el 32.8% tiene sobrepeso y el 20.5% obesidad. La seroprevalencia al Ad-36 en peso normal fue de 14.6%, mientras que en sobrepeso y obesidad fue de 9.08% y 8.6%, respectivamente. La seroprevalencia total al Ad-36 fue del 32.8%. La seropositividad se asoció con la circunferencia de cintura (OR=1.930, P=0.17). No se encontró asociación entre la seroprevalencia al Ad-36 y la obesidad ni con la concentración sérica de colesterol. Se encontró que existe una asociación entre la seropositividad al Ad-36 y la circunferencia de cintura en una población de adultos del noreste de México. ABSTRACT Purpose and method of the study: Adenovirus-36 (Ad-36) infection induces adipogenesis in animal models and accumulation of lipids in adipocytes, decreases serum concentration colesterol, therefore it is considered as a possible risk factor to develop obesity. Seroprevalence to Ad-36 antibodies was 30% in obese subjects in different parts of the world. In Mexico is unknown if association between seroprevalence to Ad-36 and obesity in adults. Objective: To determine the seroprevalence of Ad-36 and its association with obesity and colesterol serum concentration in adults of Northeast Mexico. Material and Method: Study approved by the Research, Ethics and Biosafety Committee of the School of Public Health and Nutrition registered as 17-FaSPyN-SA-09.TP. From September 2017 to March 2018, 263 volunteers aged 18-70 years, residents of Northeast Mexico who signed informed consent were recruited. Nutritional status was evaluated using anthropometric measures (weight, height, waist and hip circumferences), indexes associated with obesity were calculated and % body fat was measured by dual X-ray absorptiometry (Lunar iDxa). Blood samples were collected, the serum was stored at -80 ° C, until its use to determine the seropositivity of antibodies against Ad-36 by immunoenzymatic method (ELISA) and cholesterol serum was evaluated by cholesterol oxidaseperoxidase method. Data analysis was performed using the software SPSS version 21.0 Contributions and conclusions: According to the body mass index (BMI), 44.6% corresponds to normal weight group (BMI 18.5-24.9 kg/m2 ), 32.8% is overweight (BMI 25-30kg/m2 ) and 20.5% was obese (BMI >30kg/m2 ). The seroprevalence to Ad-36 in normal weight was 14.6%, while in overweight and obesity it was 9.08% and 8.6%, respectively. The total seroprevalence to Ad-36 was 32.8%. Seropositivity was associated with waist circumference (OR = 1.930, P = 0.17). No association was found between seroprevalence to Ad-36 and obesity or with cholesterol serum concentration. It was found that there is an association between seropositivity to Ad-36 and waist circumference in a population of adults in northeastern Mexico

Fitoplancton de dos lagunas de los humedalesde Xeresa y Xeraco (Valencia, España).

[email protected] [email protected] ha estudiado la composición fitoplanctónica de dos lagunas costeras mediterráneas, que corresponden a los marjales de Xeresa y Xeraco (Valencia). Estas zonas húmedas de la Comunidad Valenciana poseen un importante valor ecológico y botánico para nuestra Península, aunque actualmente se encuentran amenazadas por transformaciones de tipo turístico o agrícola. Las lagunas estudiadas se caracterizan por ser someras (Zmax: 3 m), oligohalinas, de aguas transparentes y mesotróficas, y por encontrarse sobre lechos de turba y con praderas de macrófitos sumergidos. El fitoplancton observado destaca por presentar una composición similar para ambas lagunas, con especies cosmopolitas y abundancia de microalgales de pequeño tamaño. Esta estructura de tamaño resulta importante para mantener las complejas redes tróficas de estos lagos someros. El grupo algal más diverso, en ambas lagunas, fue el de las clorofíceas. Sin embargo, la abundancia y biomasa algal fue acaparada por las cianofíceas filamentosas en la laguna de Xeresa, mientras que las clorofíceas y criptofíceas dominaron en la laguna de Cap de Terme.Phytoplankton composition from two Mediterranean Coastal lakes located in Xeresa and Xeraco wetlands (Valencia, Spain) were studied. These wetlands from the Comunidad Valenciana have an important ecological and botanical value for the Iberian Peninsula, although nowadays they are threatened by turistic and agriculture development. The study lakes are characterized to be shallow (Zmax: 3 m), oligohaline, water transparent, mesotrophic and peat lakes, which are covered by sumerged macrophytes. The phytoplankton observed was similar in both lakes, with cosmopolitan species and abundant small-size microalgae. This size structure is relevant for the maintenance of the complex food-webs of these shallow lakes. The most diverse algal group, in both study lakes, corresponded to chlorophytes. However, the algal abundance and biomasa was overwhelmed by cyanophytes in the lake of Xeresa, but by chlorophytes and cryptophytes in the lake of Cap de Terme

Design, characterization and application of an erbium-doped fiber laser for the study of cancer cells

This project is a continuation of the work “Design, characterization and application of an erbium-doped fiber laser for the study of cancer cells” started last year by A. Cabedo, C. Pericas, S. Sempere and A. Silva-Santisteban. The already working laser has been tuned up in order to enhance its performance. Its characteristic behaviour has been studied both by developing a numerical model and through experimental measures in the lab. In addition, a MATLAB software has been developed so the generated pulses can be easily controlled.2015/201

First record of Synedropsis roundii (Bacillariophyta, Fragilariaceae) in the Mediterranean region

[EN] Populations of the fragilarioid diatom Synedropsis roundii are described from the phytoplankton of the Albufera of Valencia, a large and shallow eutrophic lagoon in the Spanish Mediterranean coast. The specimens collected are described and illustrated with light and scanning electron microscopy. This is the first documented record of this species since its description, and the first illustrated record of the genus in the Mediterranean region. The Albufera lagoon and the type locality of the species (Imboassica Lagoon, SE Brazil) are similar in some ecological features. The ecological and biogeographical implications of this finding are briefly discussedSISEM images were kindly provided by A. Olenici at the Electronic Microscopy Unit of the University of Jaén (Spain). We are very grateful to Dr. Juan Soria from the University of Valencia (Spain) for his inestimable help during sampling in the Albufera lagoo

Tendencias del fitoplancton en el lago de la Albufera de Valencia e implicaciones para su ecología, gestión y recuperación

The lake of Albufera de Valencia, with 2320 ha, is the largest shallow, oligohaline lake of the Spanish coast. It is located within the Natural Park of the Albufera de Valencia, which is mainly formed by rice fields. This important Spanish wetland is subjected to different environmental impacts. The Albufera Lake has been eutrophic since the 1970s. Even though a diversion plan for nutrients entering the lake mainly from the north and northwest started in 1991, its effects on the system's quality have been limited. Since 1985, a continuous monitoring of the lake's phytoplankton has been carried out, which represents one the largest temporal data set for shallow Mediterranean lakes. In this study, phytoplankton trends in the lake of the Albufera de Valencia are analysed, as well as its implications for the ecology, management, restoration, and conservation of the lake and its surrounding related wetlands. A 30% nutrient diversion has not decreased the dominance of cyanobacteria in the lake's phytoplankton, although it has contributed to a change in species composition, with a trend to a decrease in filamentous cyanobacteria and an increase of chroococcal cyanobacteria. The filamentous cyanobacteria Planktothrix agardhii, has been a good indicator species of the nutrient enrichment periods in the lake. The hydrological cycle of the lake was closely related to the phytoplankton ecology and the lake food webs. The reduction of the lake water inputs has produced higher algal biomasses and the increase of algal species with adaptation strategies towards more stable water columns. The increase of Microcystis aeuroginosa and Cylindrospermopsis raciborski in the lake implies an additional risk due to their capacity to produce cyanotoxins. Data analysis leads us to conclude that the reduction in the external nutrient loading was insufficient to revert the lake's trophic state towards an improvement of its water quality, which nowadays can be classified as "bad" according to the European Water Framework Directive. Some measures are suggested in order to manage and improve the water quality of the Albufera de Valencia lake.El lago de la Albufera de Valencia, con una extensión de 2320 ha, es el lago somero y oligohalino más extenso de nuestro litoral. Se encuentra englobado dentro del Parque Natural de la Albufera de Valencia, en su mayor parte formado por arrozales. Esta importante zona húmeda de España recibe diferentes impactos ambientales. El lago de la Albufera se encuentra en estado eutrófico desde los años 1970 hasta nuestros días y aunque en 1991 se inició un plan de desvío de los nutrientes que confluían en el lago, principalmente por su zona norte y noroeste, sus efectos sobre la calidad del sistema han sido limitados. Desde 1985 hasta el presente se ha realizado un seguimiento del fitoplancton del lago de la Albufera, lo que constituye una de las series temporales más largas que existen para los lagos someros de la cuenca mediterránea. En esta contribución se analizan las tendencias del fitoplancton en el lago de la Albufera de Valencia y sus implicaciones para la ecología, gestión, recuperación y conservación del mismo, y de sus zonas húmedas asociadas. El desvío de un 30% del aporte de nutrientes al lago no ha disminuido la dominante presencia de cianobacterias en su fitoplancton, aunque ha contribuido a un cambio en la composición de especies, con una tendencia de disminución de las cianobacterias filamentosas y un aumento de las cianobacterias croococales. La cianobacteria filamentosa Planktothrix agardhii ha sido una buena indicadora de los periodos de incrementos de nutrientes en el lago. El ciclo hidrológico del lago se relacionó estrechamente con la ecología del fitoplancton y la de sus redes tróficas. La reducción de la entrada de caudales al lago ha dado lugar a un aumento de la biomasa algal y de las especies algales con estrategias de adaptación a columnas de agua más estables. El aumento en el lago de Microcystis aeuroginosa y Cylindrospermopsis raciborski supone un riesgo añadido debido a su capacidad para producir cianotoxinas. El análisis de los datos nos hace concluir que la reducción en la carga externa de nutrientes fue insuficiente para revertir el estado trófico del lago hacia un estado de mejor calidad, que puede catalogarse de "malo" según la Directiva Marco del Agua. Se recomiendan una serie de medidas que permitan mejorar y gestionar el lago de la Albufera de Valencia

Ephippial and subitaneous egg abortion: relevance for an obligate parthenogenetic Daphnia population

We experimentally analysed the importance of egg abortion in the reproduction strategies of Daphnia pulicaria (Forbes) in Lake Río Seco, a high mountain lake. Adult animals were exposed to different treatments under continuous or dynamic conditions (temperature and photoperiod) to test whether the simulation of field conditions, with changing temperature and photoperiod, induces differences in their reproductive traits in comparison to continuous conditions, with the aim of extrapolating results to the lake. Continuous conditions were the photoperiod and temperature values recorded in the lake at the time when ephippial reproduction is induced. Dynamic conditions were the changing values in the field from the continuous conditions until autumn. The number of healthy ephippial eggs per ephippium was also recorded by using sediment traps in the lake. Our results show that subitaneous and ephippial egg abortion has a major influence on an obligate parthenogenetic Daphnia population in both the laboratory and field. The total number of healthy ephippial eggs per ephippium (mean ± SE; 0.52 ± 0.12) and the proportion of released empty ephippia obtained in the sediment traps (0.73 ± 0.05) were similar to those experimentally obtained under dynamic conditions (healthy eggs per ephippium: 0.29 ± 0.16; proportion of released empty ephippia: 0.79 ± 0.11), suggesting that ephippial egg abortion and empty ephippia production are frequent in nature. This is the first study to describe Daphnia ephippial egg abortion and compare subitaneous and ephippial egg abortion between experimental and field conditions. This approach is recommended for future research into Daphnia or cladoceran reproduction.Financial support was obtained from CICYT Project CGL2004-03031/BOS and MMA Projects 129B/2003 and 87/2007

Ictiofauna del Lago de la Albufera de Valencia: evolución histórica y situación actual

P. 45-56A pesar de la importancia socioeconómica de las actividades pesqueras que de forma ancestral se vienen realizando en el Lago de la Albufera de Valencia, documentadas al menos desde el siglo XIII, existe un escaso conocimiento acerca de los la evolución temporal, situación actual e importancia ecológica de su fauna piscícola. Los datos de que se dispone son en muchos casos antiguos e incompletos, y principalmente son datos cualitativos sobre la composición de especies o basados en capturas comerciales. El objetivo de este trabajo es determinar el estado actual y los cambios de estas asociaciones de espe-cies desde los primeros registros en 1865, así como estimar su papel en la ecología y la conservación del lago. Para ello, se analizaron de forma exhaustiva los datos recogidos en la literatura, los procedentes de los registros de los pescadores, y ade-más se llevó a cabo un estudio de campo de la ictiofauna presente durante el verano de 2000 y la primavera de 2002. Los resultados permiten constatar que: a) se ha producido un notable descenso en la riqueza de especies de peces en el lago, prin-cipalmente desde la década de 1950 hasta 2002; b) se observa un aumento notable de las poblaciones de especies introduci-das, principalmente Gambusia holbrooki y Lepomis gibbosus, que han desplazado a endemismos como Aphanius iberus, Bar-bus bocagei, Chondrostoma arrigonis y Valencia hispanica; c) desde la década de 1950 las capturas de mugílidos se han incrementado (de 80 a 490 t·año-1), en detrimento de especies como Anguilla anguilla o Dicentrarchus labrax, que han des-cendido significativamente coincidiendo con la eutrofización del lago, la desaparición de la vegetación sumergida y como resultado de su sobrepesca en periodos anteriores; d) se observan ciclos estacionales en la composición especifica de las cap-turas, asociadas a la dinámica poblacional de cada especie (característica de lagos costeros) y a la regulación del flujo hidro-lógico del lago para el cultivo del arroz. Las capturas fueron máximas entre octubre y enero, lo que permitió relajar la presión de depredación sobre el macrozooplancton, con consecuencias en la red trófica y en la transparencia del agua; e) se observó una clara relación entre la fauna piscícola del Lago de la Albufera y sus cambios de estado trófico. El progresivo pro-ceso de eutrofización antropogénica que sufre este ecosistema, la introducción incontrolada de especies exóticas y la escasa conservación y gestión del lago y de sus ecosistemas asociados, así como la de sus recursos pesqueros, se apuntan como algu-nas de las principales causas de los cambios producidos en su ictiofaunaS

Xylem surfactants introduce a new element to the cohesion-tension theory

Vascular plants transport water under negative pressure without constantly creating gas bubbles that would disable their hydraulic systems. Attempts to replicate this feat in artificial systems almost invariably result in bubble formation, except under highly controlled conditions with pure water and only hydrophilic surfaces present. In theory, conditions in the xylem should favor bubble nucleation even more: there are millions of conduits with at least some hydrophobic surfaces, and xylem sap is saturated or sometimes supersaturated with atmospheric gas and may contain surface-active molecules that can lower surface tension. So how do plants transport water under negative pressure? Here, we show that angiosperm xylem contains abundant hydrophobic surfaces as well as insoluble lipid surfactants, including phospholipids, and proteins, a composition similar to pulmonary surfactants. Lipid surfactants were found in xylem sap and as nanoparticles under transmission electron microscopy in pores of intervessel pit membranes and deposited on vessel wall surfaces. Nanoparticles observed in xylem sap via nanoparticle-tracking analysis included surfactant-coated nanobubbles when examined by freeze-fracture electron microscopy. Based on their fracture behavior, this technique is able to distinguish between dense-core particles, liquid-filled, bilayer-coated vesicles/liposomes, and gas-filled bubbles. Xylem surfactants showed strong surface activity that reduces surface tension to low values when concentrated as they are in pit membrane pores. We hypothesize that xylem surfactants support water transport under negative pressure as explained by the cohesion-tension theory by coating hydrophobic surfaces and nanobubbles, thereby keeping the latter below the critical size at which bubbles would expand to form embolisms