Influence of telomerase activity and initial distribution on human follicular aging: Moving from a discrete to a continuum model

Producción CientíficaA discrete model is proposed for the temporal evolution of a population of cells sorted according to their telomeric length. This model assumes that, during cell division, the distribution of the genetic material to daughter cells is asymmetric, i.e. chromosomes of one daughter cell have the same telomere length as the mother, while in the other daughter cell telomeres are shorter. Telomerase activity and cell death are also taken into account. The continuous model is derived from the discrete model by introducing the generational age as a continuous variable in , being the Hayflick limit, i.e. the number of times that a cell can divide before reaching the senescent state. A partial differential equation with boundary conditions is obtained. The solution to this equation depends on the initial telomere length distribution. The initial and boundary value problem is solved exactly when the initial distribution is of exponential type. For other types of initial distributions, a numerical solution is proposed. The model is applied to the human follicular growth from preantral to preovulatory follicle as a case study and the aging rate is studied as a function of telomerase activity, the initial distribution and the Hayflick limit. Young, middle and old cell-aged initial normal distributions are considered. In all cases, when telomerase activity decreases, the population ages and the smaller the value, the higher the aging rate becomes. However, the influence of these two parameters is different depending on the initial distribution. In conclusion, the worst-case scenario corresponds to an aged initial telomere distribution.Ministerio de Ciencia e Innovación (PGC2018-101443-B-I00)CDTI and FEDER (IDI-20190160 and IDI-20181240)Instituto de Salud Carlos III (Spanish Government) (PI20/00252)FINOX through FORWARD 2018-6 to E.V. and J.A.G.V. and by IVIRMA (2004-FIVI-041-MV; 1711-FIVI-111-MV; 1707-FIVI-084-MV; 1711-FIVI-112-MV; 2207-MAD-093-MV)

High dark CO2 fixation rates by active chemolithoautotrophic microbes along the water column (100-5000m) off Galicia (NW Iberian margin)

Poster communicationOur results provide evidence for the significant contribution to chemolithotrophy by specific archaeal and bacterial groups in the dark ocean

Diversity and abundance of planktonic communities in the deep waters off the galician coast (NW Spain)

Comunicación oralPlanktonic communities play pivotal roles within marine ecosystems, affecting their structure, functioning and services. Although they have been extensively studied in the epipelagic ocean, the knowledge about these communities in the dark ocean is rather short. In this study, we explored patterns of abundance and biomass of a wide variety of taxonomic groups from the prokaryotes to mesozooplankton in the epi-, meso- and bathypelagic waters off the Galician coast. As expected, ciliate and zooplankton abundances are depleted in the bathypelagic waters relative to abundances of prokaryotes and nanoflagellates. The rate of decrease of zooplankton biomass with depth is twice as that of prokaryotes and nanoflagellates, indicating that relative contribution of mesozooplancton to the total plankton biomass decreases with depth. Overall, the diversity of prokaryotes in the dark ocean is almost as high as in the epipelagic layer, although the phylotypes are different. The major fraction of epipelagic ciliates belongs to alloricate genera, whereas tintinnids dominate the deep ciliate populations. Small copepods were dominant in the epi- and meso-pelagic zone. By contrast, foraminiferans, big copepods and myctophic fishes were more abundant in the deep ocean

Interface barriers for flux motion in high-temperature superconducting superlattices

We study angular dependent magnetoresistance in the vortex-liquid phase of epitaxial YBa2Cu3O7 thin films and YBa_2Cu_3O_7/PrBa_2Cu_3O_7 superlattices. Superlattices were grown with different PrBa_2Cu_3O_7 thickness in order to tune coupling between YBa_2Cu_3O_7 layers. While dissipation of single film and coupled superlattices is scaled with the anisotropic three-dimensional model in the whole angular range, decoupling through PrBa_2Cu_3O_7 spacer breaks down the scaling and yields strong reduction of the dissipation when the magnetic fields are applied up to ±20degrees around the interface direction. Bean-Livingston barriers at the interface are the mechanism which governs this behavior

Changes in bacterial activity and community composition in response to water mass mixing

PosterMixing zones and boundaries between different water masses are "hot spots" of marine biodiversity and activity. We aimed to investigate the effects of water mass mixing in the dark-ocean microbial communities by collecting and incubating natural bacterial communities from the Mediterranean Water (MW; at 1000 m depth), the Subpolar Modal Water (SPMW, 500m) and the Labrador Sea Water (LSW, 1800 m), and comparing them with artificially mixed communities. Mixing experiment 1 consisted of incubating at in sity conditions the original LSW and MW communities, plus a mixture of both (MIX1, dilution 1:1), whereas the Mixing experiment 2 included the original prokaryotic communities from SPMW and MW and a mixture of both (MIX2, dilution 1:1). Bacterial abundance and activity was monitored every 24 h over 8 days, while bacterial community composition and DOM characterization were assessed at the beginning (day 0), middle (day 4) and at the end of the experiment (day 8). Live prokaryotic cell abundance was higher in the MIX1 and MIX2 treatments as compared to the original communities. Moreover, MIX bacteria showed slightly higher leucine incorporation rates than MW or LSW. These metabolic responses were accompanied by changes in the optical properties of DOM, suggesting a change in the dynamics of the organic matter. Taken together, our results indicate differences in the bio-reactvity of the organic matter after mixing as compared to the original water masses that could influence the composition and activity of the bacterial community

Changes in activity and community composition shape bacterial responses to size-fraccionated marine DOM

To study the response of bacteria to different size-fractions of naturally occurring dissolved organic matter (DOM), a natural prokaryotic community from North Atlantic mesopelagic waters (1000 m depth) was isolated and grown in (i) 0.1-µm filtered seawater (CONTROL), (ii) the low-molecular-weight (<1 kDa) DOM fraction (L-DOM), and (iii) the recombination of high- (>1 kDa) and low-molecular-weight DOM fractions (H + L-DOM), to test the potential effect of ultrafiltration on breaking the DOM size continuum. Prokaryotic abundance and leucine incorporation were consistently higher in the H + L-DOM niche than in the L-DOM and CONTROL treatments, suggesting a different interaction with each DOM fraction and the disruption of the structural DOM continuum by ultrafiltration, respectively. Rhodobacterales (Alphaproteobacteria) and Flavobacteriales (Bacteroidetes) were particularly enriched in L-DOM and closely related to the colored DOM (CDOM) fraction, indicating the tight link between these groups and changes in DOM aromaticity. Conversely, some other taxa that were rare or undetectable in the original bacterial community were enriched in the H + L-DOM treatment (e.g., Alteromonadales belonging to Gammaproteobacteria), highlighting the role of the rare biosphere as a seed bank of diversity against ecosystem disturbance. The relationship between the fluorescence of protein-like CDOM and community composition of populations in the H + L-DOM treatment suggested their preference for labile DOM. Conversely, the communities growing on the L-DOM niche were coupled to humic-like CDOM, which may indicate their ability to degrade more reworked DOM and/or the generation of refractory substrates (as by-products of the respiration processes). Most importantly, L- and/or H + L-DOM treatments stimulated the growth of unique bacterial amplicon sequence variants (ASVs), suggesting the potential of environmental selection (i.e., changes in DOM composition and availability), particularly in the light of climate change scenarios. Taken together, our results suggest that different size-fractions of DOM induced niche-specialization and differentiation of mesopelagic bacterial communities.Versión del edito

Artificially induced reduction of the dissipation anisotropy in high-temperature superconductors

Bi_2Sr_2CaCu_2O_8, RBa_2Cu_3O_7 (R=Y, Eu) thin films and RBa_2Cu_3O_7/PrBa_2Cu_3O_7 superlattices have been fabricated by sputtering technique. The anisotropic dissipation was measured close to the critical temperatures with high applied magnetic fields rotating from parallel to perpendicular to the substrate. In multilayers, in a large magnetic field interval, the dissipation anisotropy is reduced as much as 60% in comparison with the most anisotropic system (Bi_2Sr_2CaCu_2O_8) and at least 50% at 30 kOe in comparison with 123 films. This strong anisotropy reduction is discussed taking into account the role played by the superlattice modulation lengths on magnetic matching effects and coupling between the superconducting layers

El macrobentos y su relación con las fluctuaciones de salinidad en ríos y esteros del Chaco Oriental (Argentina)

In the area comprised between the Pilcomayo river (Formosa province) and the Amores river (Santa Fe province) 17 streams and rivers, and 4 swamps ("esteros") were studied in their lower reaches during low and high water periods. The salinity was high in some of them, specially during low water. Samples were taken with a Dietz-LaFond and modified Drzycimski dredges, according to the substrate characteristics, and filteres through a 500μm mesh size. Relative abundance and density (ind. m-2) were analized in relation with the main environmental factors, as current speed, conductivity, dissolved oxigen and sediment granulometry. The benthic macrofauna occurring in the streams and rivers showed important differences in their composition and density, being oligochaetes (Naididae and Tubificidae), chironomids (Chironominae) and molluscs (Hydrobiidae),&nbsp;the main groups.The swamp bottom fauna was rather poor, with abundance of oligochaetes, which could be due to the scarcity of dissolved oxygen and the high proportion of organic matter. The well oxigenated lotic environments, with moderate conductivity values, showed the richest and most abundant macrofauna, in contrast with those of high salinity, specially when the water level decreased. Conductivity was negatively correlated with the species number ( P &lt; 0,01) and abundance (P&lt; 0,01).In the area comprised between the Pilcomayo river (Formosa province) and the Amores river (Santa Fe province) 17 streams and rivers, and 4 swamps ("esteros") were studied in their lower reaches during low and high water periods. The salinity was high in some of them, specially during low water. Samples were taken with a Dietz-LaFond and modified Drzycimski dredges, according to the substrate characteristics, and filteres through a 500μm mesh size. Relative abundance and density (ind. m-2) were analized in relation with the main environmental factors, as current speed, conductivity, dissolved oxigen and sediment granulometry. The benthic macrofauna occurring in the streams and rivers showed important differences in their composition and density, being oligochaetes (Naididae and Tubificidae), chironomids (Chironominae) and molluscs (Hydrobiidae),&nbsp;the main groups.The swamp bottom fauna was rather poor, with abundance of oligochaetes, which could be due to the scarcity of dissolved oxygen and the high proportion of organic matter. The well oxigenated lotic environments, with moderate conductivity values, showed the richest and most abundant macrofauna, in contrast with those of high salinity, specially when the water level decreased. Conductivity was negatively correlated with the species number ( P &lt; 0,01) and abundance (P&lt; 0,01)

Entrevista al arquitecto Renato Bocchi

El entrevistado reflexiona sobre las relaciones entre arquitectura y paisaje desarrollando el concepto de 'landmark'.Facultad de Arquitectura y Urbanism

El Bentos del Parana Media en el tramo Corrientes-Esquina

Quali-quantitative variations of the benthos from the Middle Paraná river course, were studied. Spatial and temporal distribution was analyzed in relation with the main environmental factors. Studies were monthly carried out during March 1981-March 1982 in four stations near the localities of Comentes, Bella Vista, Coya and Esquina. In each of them, four sampling points were stablished in the cross sections of the river. Samples were obtained with a Dietz-LaFond dredge and fíltered through 500 and 150 µm mesh opening screens. The predominant sandy bottoms are inhabited by a specialized psammophilous fauna. The community structure was similar along all the studied stretch. Abundánce was very fluctuant, with maximun valúes of 160.000 ind/m2 with a strong numerical dominance of a species of Oligochaeta: Narapa bonettoi Correlations análysis showed a positive association between the mean grain size and the total abundance. These coeflcients were signiñcatives in all the stations for microturbellarians but only in Goya and Esquina for N. bonettoi Clay bank substraía from the river margins had a richer but less abundant fauna (maximun valúes of 29.000 ind/m2) with predominance of Xenochironomus sp. The benthos of the soft silty bottoms was the least diversé and abundant. Seasonal changes in the abundance were observed. There was an increment in spring and the early summer with a tendency to decrease during summer floods. This pattem was similar in the thxee kinds of bottoms, but more evident in the soft silty ones.Quali-quantitative variations of the benthos from the Middle Paraná river course, were studied. Spatial and temporal distribution was analyzed in relation with the main environmental factors. Studies were monthly carried out during March 1981-March 1982 in four stations near the localities of Comentes, Bella Vista, Coya and Esquina. In each of them, four sampling points were stablished in the cross sections of the river. Samples were obtained with a Dietz-LaFond dredge and fíltered through 500 and 150 µm mesh opening screens. The predominant sandy bottoms are inhabited by a specialized psammophilous fauna. The community structure was similar along all the studied stretch. Abundánce was very fluctuant, with maximun valúes of 160.000 ind/m2 with a strong numerical dominance of a species of Oligochaeta: Narapa bonettoi Correlations análysis showed a positive association between the mean grain size and the total abundance. These coeflcients were signiñcatives in all the stations for microturbellarians but only in Goya and Esquina for N. bonettoi Clay bank substraía from the river margins had a richer but less abundant fauna (maximun valúes of 29.000 ind/m2) with predominance of Xenochironomus sp. The benthos of the soft silty bottoms was the least diversé and abundant. Seasonal changes in the abundance were observed. There was an increment in spring and the early summer with a tendency to decrease during summer floods. This pattem was similar in the thxee kinds of bottoms, but more evident in the soft silty ones