Fluctuations and differential contraction during regeneration of Hydra vulgaris tissue toroids

We studied regenerating bilayered tissue toroids dissected from Hydra vulgaris polyps and relate our macroscopic observations to the dynamics of force-generating mesoscopic cytoskeletal structures. Tissue fragments undergo a specific toroid–spheroid folding process leading to complete regeneration towards a new organism. The time scale of folding is too fast for biochemical signalling or morphogenetic gradients, which forced us to assume purely mechanical self-organization. The initial pattern selection dynamics was studied by embedding toroids into hydro-gels, allowing us to observe the deformation modes over longer periods of time.We found increasing mechanical fluctuations which break the toroidal symmetry, and discuss the evolution of their power spectra for various gel stiffnesses. Our observations are related to singlecell studies which explain the mechanical feasibility of the folding process. In addition, we observed switching of cells from a tissue bound to a migrating state after folding failure as well as in tissue injury. We found a supra-cellularactin ring assembled along the toroid’s inner edge. Its contraction can lead to the observed folding dynamics as we could confirm by finite element simulations. This actin ring in the inner cell layer is assembled by myosin-driven length fluctuations of supra-cellular F-actin bundles (myonemes) in the outer cell layer

Caracterización limnológica del agua, las algas y los barros utilizados en el Complejo Termal Copahue (Neuquén, Argentina)

We carried out the physicochemical characterization of extreme environments of acidic geothermal springs of the Copahue Thermal Complex, and isolated and cultivated algae used for therapeutic and medicinal purposes. Ecophysiological aspects, algal photosynthetic responses and potential toxicity of sediments were analysed. At the 15 sampling sites (pH: 2.0-6.7, conductivity: 283-3230 µS/cm, temperature: 22-60°C), 11 Cyanobacteria species of a total of 24 algae were identified. The species richness was low with true inhabitants of highly acidic waters: Cyanidium caldarium, Euglena mutabilis, Chlamydomonas acidophila, Achnanthidium minutissimum, and Eunotia exigua, and cosmopolitan species of thermal springs: Mastigocladus laminosus, Leptolyngbia boryana and Phormidium tergestinum. All the species were well adapted to low light levels (15-55 µmol photon.m-2.s-1), and photosynthetic responses were similar to those in comparable environments. pH and temperature were important factors in algal distribution, and N:P relationship suggests that P is the limiting nutrient for algal growth. Fractions controlling P availability in the muds were those bound to organic matter, and Fe/Al oxyhydroxides. Healing muds have the ability to precipitate metals and would not be toxic. Cadmium and other potentially toxic metals were in very low concentrations and pose no risk for the human use as healing muds and bathing.Se realizó la caracterización físico-química de los ambientes extremos (aguas termales y barros) del Complejo Termal Copahue, y se aislaron y cultivaron algas empleadas con propósitos medicinales y terapéuticos. Se analizaron aspectos ecofisiológicos de las especies y sus respuestas fotosintéticas, así como la potencial toxicidad de los barros. En los 15 sitios muestreados (pH: 2.0-6.7, conductividad: 283-3230 µS/cm, temperatura: 22-60 °C) se identificaron 11 especies de cianobacterias de un total de 24 especies algales. La riqueza específica fue baja, con especies representativas de ambientes ácidos: Cyanidium caldarium, Euglena mutabilis, Chlamydomonas acidophila, Achnanthidium minutissimum y Eunotia exigua, y especies cosmopolitas de aguas termales: Mastigocladus laminosus, Leptolyngbia boryana y Phormidium tergestinum. Todas las especies mostraron estar bien adaptadas a bajas intensidades lumínicas (15-55 µmol fotones.m-2.s-1) y sus respuestas fotosintéticas resultaron comparables a las de ambientes similares. El pH y la temperatura fueron factores importantes en la distribución de las algas, y la alta relación N:P sugiere que el P es el nutriente limitante del crecimiento algal. Las fracciones que controlaron la disponibilidad de P en los sedimentos fueron las de materia orgánica y de oxihidróxidos de Fe/Al. Los barros terapéuticos mostraron capacidad para precipitar los metales y no serían tóxicos. El Cd y otros metales potencialmente tóxicos estuvieron presentes en muy bajas concentraciones y no representarían un riesgo para uso humano como barros curativos y baños.Fil: Flores Melo, Elizabeth Ximena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; ArgentinaFil: de la Rosa, Iris Nadia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; ArgentinaFil: Baffico, Gustavo Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; ArgentinaFil: Temporetti, Pedro Felix. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; ArgentinaFil: Wenzel, María T.. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental; ArgentinaFil: Cabrera, Juan Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; ArgentinaFil: Pedrozo, Fernando Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; ArgentinaFil: Diaz, Monica Mabel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; Argentin

Fluctuations and differential contraction during regeneration of Hydra vulgaris tissue toroids

We studied regenerating bilayered tissue toroids dissected from Hydra vulgaris polyps and relate our macroscopic observations to the dynamics of force-generating mesoscopic cytoskeletal structures. Tissue fragments undergo a specific toroid-spheroid folding process leading to complete regeneration towards a new organism. The time scale of folding is too fast for biochemical signalling or morphogenetic gradients which forced us to assume purely mechanical self-organization. The initial pattern selection dynamics was studied by embedding toroids into hydro-gels allowing us to observe the deformation modes over longer periods of time. We found increasing mechanical fluctuations which break the toroidal symmetry and discuss the evolution of their power spectra for various gel stiffnesses. Our observations are related to single cell studies which explain the mechanical feasibility of the folding process. In addition, we observed switching of cells from a tissue bound to a migrating state after folding failure as well as in tissue injury. We found a supra-cellular actin ring assembled along the toroid's inner edge. Its contraction can lead to the observed folding dynamics as we could confirm by finite element simulations. This actin ring in the inner cell layer is assembled by myosin- driven length fluctuations of supra-cellular {\alpha}-actin structures (myonemes) in the outer cell-layer.Comment: 19 pages and 8 figures, submitted to New Journal of Physic

Cianobacterias ácido-termófilas del complejo termal copahue, Neuquén, Argentina

El objetivo de este trabajo fue identificar las especies de cianobacterias ácido-termófilas que, junto con las aguas, microalgas y fangos, son importantes recursos termales utilizados con fines terapéuticos en el Complejo Termal Copahue. El trabajo presenta descripciones, comentarios e ilustraciones de las 11 especies identificadas pertenecientes a nueve géneros: Chroococcidiopsis, Chroococcus, Kamptonema, Komvophoron, Leptolyngbya, Mastigocladus, Oscillatoria, Phormidium y Spirulina recolectadas en diez sitios de muestreo. Cinco especies: Chroococcus membraninus, Chroococcidiopsis thermalis, Spirulina gracilis, Phormidium thermobium y Komvophoron jovis, son citadas por primera vez para la Argentina. Además, se aislaron y mantuvieron en cultivo unialgal cuatro especies: Chroococcus membraninus, Chroococcidiopsis thermalis, Kamptonema animale y Mastigocladus laminosus. M. laminosus resultó ser la especie encontrada con mayor frecuencia en el área, ya que se la registró en ocho de los diez sitios. La Laguna Los Callos fue el sitio con mayor diversidad, donde se registró el mayor número de especies, ocho en total. Todas las especies de cianobacterias estudiadas en el presente trabajo son utilizadas, ya sea mediante la aplicación directa de las matas o por la utilización de sus componentes activos, en las aguas y en los fangosThe objective of this work was to identify the species of acid-thermophilic cyanobacteria which,together with the waters, microalgae and mud, are important thermal resources used for therapeuticpurposes in the Copahue Thermal Complex. The work presents descriptions, comments, and illustrationsof the 11 identified species belonging to nine genera: Chroococcidiopsis, Chroococcus, Kamptonema,Komvophoron, Leptolyngbya, Mastigocladus, Oscillatoria, Phormidium and Spirulina, collected inten sampling sites. Five species: Chroococcus membraninus, Chroococcidiopsis thermalis, Spirulinagracilis, Phormidium thermobium, and Komvophoron jovis, are cited for the first time for Argentina. In addition, four species were isolated and maintained in unialgal culture: Chroococcus membraninus, Chroococcidiopsis thermalis, Kamptonema animale and Mastigocladus laminosus. M. laminosus was the most frequently encountered species of the area, since it was found in eight of the ten sites. The Laguna Los Callos was the most diverse site, with the largest number of species, eight in total. All the species of cyanobacteria studied in the present work are used, either through the direct application of themats or through the use of their active components in water, and mud.Fil: Flores Melo, Elizabeth Ximena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; ArgentinaFil: de la Rosa, Iris Nadia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; ArgentinaFil: Wenzel, Maria Teresa. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental; ArgentinaFil: Diaz, Monica Mabel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; Argentin

Reexamination of a Meta-Analysis of the Effect of Antioxidant Supplementation on Mortality and Health in Randomized Trials

A recent meta-analysis of selected randomized clinical trials (RCTs), in which population groups of differing ages and health status were supplemented with various doses of β-carotene, vitamin A, and/or vitamin E, found that these interventions increased all-cause mortality. However, this meta-analysis did not consider the rationale of the constituent RCTs for antioxidant supplementation, none of which included mortality as a primary outcome. As the rationale for these trials was to test the hypothesis of a potential benefit of antioxidant supplementation, an alternative approach to a systematic evaluation of these RCTs would be to evaluate this outcome relative to the putative risk of greater total mortality. Thus, we examined these data based on the primary outcome of the 66 RCTs included in the meta-analysis via a decision analysis to identify whether the results provided a positive (i.e., benefit), null or negative (i.e., harm) outcome. Our evaluation indicated that of these RCTs, 24 had a positive outcome, 39 had a null outcome, and 3 had a negative outcome. We further categorized these interventions as primary (risk reduction in healthy populations) or secondary (slowing pathogenesis or preventing recurrent events and/or cause-specific mortality) prevention or therapeutic (treatment to improve quality of life, limit complications, and/or provide rehabilitation) studies, and determined positive outcomes in 8 of 20 primary prevention studies, 10 of 34 secondary prevention studies, and 6 out of 16 therapeutic studies. Seven of the eight RCTs with a positive outcome in primary prevention included participants in a population where malnutrition is frequently described. These results suggest that analyses of potential risks from antioxidant supplementation should be placed in the context of a benefit/risk ratio

Diverse molecular causes of unsolved autosomal dominant tubulointerstitial kidney diseases

Autosomal Dominant Tubulointerstitial Kidney Disease (ADTKD) is caused by mutations in one of at least five genes and leads to kidney failure usually in mid adulthood. Throughout the literature, variable numbers of families have been reported, where no mutation can be found and therefore termed ADTKD-not otherwise specified. Here, we aim to clarify the genetic cause of their diseases in our ADTKD registry. Sequencing for all known ADTKD genes was performed, followed by SNaPshot minisequencing for the dupC (an additional cytosine within a stretch of seven cytosines) mutation of MUC1. A virtual panel containing 560 genes reported in the context of kidney disease (nephrome) and exome sequencing were then analyzed sequentially. Variants were validated and tested for segregation. In 29 of the 45 registry families, mutations in known ADTKD genes were found, mostly in MUC1. Sixteen families could then be termed ADTKD-not otherwise specified, of which nine showed diagnostic variants in the nephrome (four in COL4A5, two in INF2 and one each in COL4A4, PAX2, SALL1 and PKD2). In the other seven families, exome sequencing analysis yielded potential disease associated variants in novel candidate genes for ADTKD; evaluated by database analyses and genome-wide association studies. For the great majority of our ADTKD registry we were able to reach a molecular genetic diagnosis. However, a small number of families are indeed affected by diseases classically described as a glomerular entity. Thus, incomplete clinical phenotyping and atypical clinical presentation may have led to the classification of ADTKD. The identified novel candidate genes by exome sequencing will require further functional validation

Fluctuations and differential contraction during regeneration of Hydra vulgaris tissue toroids

We studied regenerating bilayered tissue toroids dissected from Hydra vulgaris polyps and relate our macroscopic observations to the dynamics of force-generating mesoscopic cytoskeletal structures. Tissue fragments undergo a specific toroid–spheroid folding process leading to complete regeneration towards a new organism. The time scale of folding is too fast for biochemical signalling or morphogenetic gradients, which forced us to assume purely mechanical self-organization. The initial pattern selection dynamics was studied by embedding toroids into hydro-gels, allowing us to observe the deformation modes over longer periods of time.We found increasing mechanical fluctuations which break the toroidal symmetry, and discuss the evolution of their power spectra for various gel stiffnesses. Our observations are related to singlecell studies which explain the mechanical feasibility of the folding process. In addition, we observed switching of cells from a tissue bound to a migrating state after folding failure as well as in tissue injury. We found a supra-cellularactin ring assembled along the toroid’s inner edge. Its contraction can lead to the observed folding dynamics as we could confirm by finite element simulations. This actin ring in the inner cell layer is assembled by myosin-driven length fluctuations of supra-cellular F-actin bundles (myonemes) in the outer cell layer

Fluctuations and differential contraction during regeneration of Hydra vulgaris tissue toroids

We studied regenerating bilayered tissue toroids dissected from Hydra vulgaris polyps and relate our macroscopic observations to the dynamics of force-generating mesoscopic cytoskeletal structures. Tissue fragments undergo a specific toroid–spheroid folding process leading to complete regeneration towards a new organism. The time scale of folding is too fast for biochemical signalling or morphogenetic gradients, which forced us to assume purely mechanical self-organization. The initial pattern selection dynamics was studied by embedding toroids into hydro-gels, allowing us to observe the deformation modes over longer periods of time.We found increasing mechanical fluctuations which break the toroidal symmetry, and discuss the evolution of their power spectra for various gel stiffnesses. Our observations are related to singlecell studies which explain the mechanical feasibility of the folding process. In addition, we observed switching of cells from a tissue bound to a migrating state after folding failure as well as in tissue injury. We found a supra-cellularactin ring assembled along the toroid’s inner edge. Its contraction can lead to the observed folding dynamics as we could confirm by finite element simulations. This actin ring in the inner cell layer is assembled by myosin-driven length fluctuations of supra-cellular F-actin bundles (myonemes) in the outer cell layer