Dielectric and dynamic mechanical study of the mobility of poly(t-butylacrylate) chains in diblock copolymers: polystyrene-b-poly(t-butylacrylate)

A calorimetric, dielectric and dynamic-mechanical study of the dynamics of the poly(t-butyl acrylate) (PtBa) chains has been carried out in a PtBa homopolymer and two polystyrene (PS)-b-PtBa block copolymers with different PtBa chain lengths. The DSC results show that the size of the cooperative rearranging regions is similar in the homopolymers and the copolymers, both for the PtBa rich- and the PS-rich regions. Therefore, no significant contributions are found arising from composition fluctuations in the copolymers. The relaxation map obtained from dielectric relaxation indicates that there are no differences in the temperature dependence of the α-relaxation of the PtBa block in the three samples studied. However, there are larger differences for the values obtained from DMTA experiments. Contrary to the α-relaxation, the relaxation map for the β-transition shows that the characteristic times for the PtBa blocks are smaller in the homopolymer than in the copolymers. In principle, these are unexpected results because the β-relaxations have a more local character than the α-ones. The width of the α-relaxation increases with T for all the samples, and it is slightly larger for the copolymers. The intensity of the α-relaxation is larger (between 3 and 4 times) for the homopolymer. Considering the molecular weights of the PtBa blocks, this effect has to be ascribed to the existence of frozen amorphous PtBa due to the existence of the glassy PS domains in the microphase separated copolymers. Molecular Dynamic Simulations (MDSs) for different sequences of the polymers under study were carried out. The conformational analysis was carried out between 1000 and 1700 K. The analysis of the variation of angles 1 and 2 of the ester group of PtBa points out the existence of a correlation between the conformational changes of the side group of the polymer chains and their relaxational behaviour

Fijación de invertebrados en tres tipos de substratos artificiales en el estero de Sabancuy, Campeche, Golfo de México

For sessile invertebrate, the settlement larval behavior and the selection of the fixation substrate is critical to the subsequent development of the adult organism. A comparative analysis of two spawn season in 2018 and three substrate types (two plastic and one biogenic) for the settlement and growth of benthic organism, in the inlet of the Sabancuy Estuary of the Terminos Lagoon, Campeche, Gulf of Mexico was carried out.  The comparisons between the length and breadth of the shell of Crassostrea virginica as an expression of growth for those seasons and those types of substrate were provided because the commercial importance of this specie. The most efficient substratum in the established context, was the biogenic one (46.78 % of all attachments), as well as the sites two in both spawn seasons (>1000 attachment); getting improves outputs in the second season (August). The group more opportunists were of the Cirripedian crustaceans in both seasons.  The group that presented biggest fluctuations in their relative frequency was the sponges. In both seasons, the same pattern was observed for Crassostrea with sizes a wide range of variation, therefore it is likely that the gradual attachment of post- larvae favors and allows the establishment of small size and the subsequent growth of existing ones.Para los invertebrados sésiles, el comportamiento del asentamiento larval y la selección del substrato final para su fijación es crítico para el posterior desarrollo del organismo adulto. En el presente trabajo se realizó un análisis comparativo de dos temporadas en 2018, y de tres tipos de substratos artificiales: dos de plástico y uno biogénico para la fijación de larvas de organismos en la boca del Estero de Sabancuy de la Laguna de Términos, Campeche. Se realizaron comparaciones entre la longitud y amplitud de la concha de Crassostrea virginica como expresión de crecimiento para esas temporadas y para esos tipos de substrato dada su importancia comercial. El substrato más eficiente en el contexto establecido fue el tipo biogénico (46,78 % del total de las fijaciones), así como la estación dos en ambas épocas (>1000 fijaciones), obteniendo mejores resultados en la segunda época (agosto).  El grupo más oportunista fue el de los crustáceos Cirripedios en ambas temporadas.  El grupo que presentó mayores fluctuaciones en su frecuencia relativa fueron las esponjas. En ambas temporadas se observó un patrón de tallas semejante para Crassostrea, solo que con un intervalo amplio de variación; por consiguiente, es probable que se favorezca la fijación progresiva de post  larvas y permita el establecimiento de tallas pequeñas y el sucesivo crecimiento de las ya existente

Niche Partitioning of Feather Mites within a Seabird Host, Calonectris borealis

According to classic niche theory, species can coexist in heterogeneous environments by reducing interspecific competition via niche partitioning, e.g. trophic or spatial partitioning. However, support for the role of competition on niche partitioning remains controversial. Here, we tested for spatial and trophic partitioning in feather mites, a diverse and abundant group of arthropods. We focused on the two dominant mite species, Microspalax brevipes and Zachvatkinia ovata, inhabiting flight feathers of the Cory's shearwater, Calonectris borealis. We performed mite counts across and within primary and tail feathers on free-living shearwaters breeding on an oceanic island (Gran Canaria, Canary Islands). We then investigated trophic relationships between the two mite species and the host using stable isotope analyses of carbon and nitrogen on mite tissues and potential host food sources. The distribution of the two mite species showed clear spatial segregation among feathers; M. brevipes showed high preference for the central wing primary feathers, whereas Z. ovata was restricted to the two outermost primaries. Morphological differences between M. brevipes and Z. ovata support an adaptive basis for the spatial segregation of the two mite species. However, the two mites overlap in some central primaries and statistical modeling showed that Z. ovata tends to outcompete M. brevipes. Isotopic analyses indicated similar isotopic values for the two mite species and a strong correlation in carbon signatures between mites inhabiting the same individual host suggesting that diet is mainly based on shared host-associated resources. Among the four candidate tissues examined (blood, feather remains, skin remains and preen gland oil), we conclude that the diet is most likely dominated by preen gland oil, while the contribution of exogenous material to mite diets is less marked. Our results indicate that ongoing competition for space and resources plays a central role in structuring feather mite communities. They also illustrate that symbiotic infracommunities are excellent model systems to study trophic ecology, and can improve our understanding of mechanisms of niche differentiation and species coexistence

'More Than Meets the Eye': cryptic diversity and contrasting patterns of host-specificity in feather mites inhabiting seabirds

Feather mites are useful models for studying speciation due to their high diversity and strong degree of host specialization. However, studies to date have focused on the evolution of higher-level mite taxa while much hidden diversity likely occurs at the level of host genera and species. In this study, we examined the diversity and evolution of feather mites infesting six sympatric seabird species from six genera, breeding in the Cape Verde archipelago. We report 32 feather mite morphospecies categorized into 10 genera and three families, of which nine correspond to new, undescribed species. Molecular data corroborated morphological species descriptions, except for two morphologically-cryptic, but genetically distinct mite lineages related to Zachvatkinia oceanodromae and Laminalloptes simplex. Using these communities, we then applied a co-structure approach to test the contribution of ectosymbiont and host factors in driving feather mite evolution. Most seabird species hosted specific and unique feather mite species, even under sympatric conditions, and in general, feather mite species exhibited strong host-driven genetic structure. However, patterns of genetic differentiation were variable. That is, some mite species are more generalist than others and mite lineages/haplotypes can be shared by related seabird species. Interestingly, host-specific mites (e.g., Zachvatkinia spp.) tend to display much higher intra-specific diversity compared to more generalist mites (e.g., Microspalax and Plicatalloptes spp.). We discuss ectosymbiont and host life-history traits that might generate these patterns, such as host dispersal and breeding behavior and/or mite spatial and trophic specialization. Our findings highlight both the vast and largely unrecognized diversity of avian feather mites on seabirds, and the intrinsic complexity of the ecological processes underlying the evolution of these ectosymbionts

Seabirds and the circulation of Lyme borreliosis bacteria in the North Pacific

Seabirds act as natural reservoirs to Lyme borreliosis spirochetes and may play a significant role in the global circulation of these pathogens. While Borrelia burgdorferi sensu lato (Bbsl) has been shown to occur in ticks collected from certain locations in the North Pacific, little is known about interspecific differences in exposure within the seabird communities of this region. We examined the prevalence of anti-Bbsl antibodies in 805 individuals of nine seabird species breeding across the North Pacific. Seroprevalence varied strongly among species and locations. Murres (Uria spp.) showed the highest antibody prevalence and may play a major role in facilitating Bbsl circulation at a worldwide scale. Other species showed little or no signs of exposure, despite being present in multispecific colonies with seropositive birds. Complex dynamics may be operating in this wide scale, natural hostparasite system, possibly mediated by the host immune system and host specialization of the tick vector

Identification of candidate pelagic marine protected areas through a seabird seasonal-, multispecific- and extinction risk-based approach

With increasing pressure on the oceans from environmental change, there has been a global call for improved protection of marine ecosystems through the implementation of marine protected areas (MPAs). Here, we used species distribution modelling (SDM) of tracking data from 14 seabird species to identify key marine areas in the southwest Atlantic Ocean, valuing areas based on seabird species occurrence, seasonality and extinction risk. We also compared overlaps between the outputs generated by the SDM and layers representing important human threats (fishing intensity, ship density, plastic and oil pollution, ocean acidification), and calculated loss in conservation value using fishing and ship density as cost layers. The key marine areas were located on the southern Patagonian Shelf, overlapping extensively with areas of high fishing activity, and did not change seasonally, while seasonal areas were located off south and southeast Brazil and overlapped with areas of high plastic pollution and ocean acidification. Non-seasonal key areas were located off northeast Brazil on an area of high biodiversity, and with relatively low human impacts. We found support for the use of seasonal areas depending on the seabird assemblage used, because there was a loss in conservation value for the seasonal compared to the non-seasonal approach when using ‘cost’ layers. Our approach, accounting for seasonal changes in seabird assemblages and their risk of extinction, identified additional candidate areas for incorporation in the network of pelagic MPAs

Projected distributions of Southern Ocean albatrosses, petrels and fisheries as a consequence of climatic change

Given the major ongoing influence of environmental change on the oceans, there is a need to understand and predict the future distributions of marine species in order to plan appropriate mitigation to conserve vulnerable species and ecosystems. In this study we use tracking data from seven large seabird species of the Southern Ocean (black-browed albatross Thalassarche melanophris, grey-headed albatross T. chrysostoma, northern giant petrel Macronectes halli, southern giant petrel M. giganteus, Tristan albatross Diomedea dabbenena, wandering albatross D. exulans and white-chinned petrel Procellaria aequinoctialis, and on fishing effort in two types of fisheries (characterised by low or high-bycatch rates), to model the associations with environmental variables (bathymetry, chlorophyll-a concentration, sea surface temperature and wind speed) through ensemble species distribution models. We then projected these distributions according to four climate change scenarios built by the Intergovernmental Panel for Climate Change for 2050 and 2100. The resulting projections were consistent across scenarios, indicating that there is a strong likelihood of poleward shifts in distribution of seabirds, and several range contractions (resulting from a shift in the northern, but no change in the southern limit of the range in four species). Current trends for southerly shifts in fisheries distributions are also set to continue under these climate change scenarios at least until 2100; some of these may reflect habitat loss for target species that are already over-fished. It is of particular concern that a shift in the distribution of several highly threatened seabird species would increase their overlap with fisheries where there is a high-bycatch risk. Under such scenarios, the associated shifts in distribution of seabirds and increases in bycatch risk will require much-improved fisheries management in these sensitive areas to minimise impacts on populations in decline

"Click & collect" para una rápida adaptación de la docencia práctica presencial a online en grados universitarios de Ciencias de la Salud

La obligada adaptación del proceso enseñanza/aprendizaje a entornos no presenciales, debido a la expansión del virus SARS-COV-2, ha motivado el diseño y ejecución de herramientas de aprendizaje basadas en TICs, que integren, además de los contenidos indispensables para la adquisición de competencias profesionales, un entorno atractivo para el aprendizaje autónomo de los alumnos. Mediante un paquete informático de implementación rápida ("click & collect") en plataformas virtuales de diferentes universidades, adaptado al nivel medio de conocimientos informáticos del profesorado en Ciencias de la Salud, se han diseñado unas clases prácticas de la asignatura Farmacognosia y Fitoterapia correspondiente a los Grados de Farmacia y Farmacia y Nutricion Humana y Dietética de la UCM y las Universidades CEU San Pablo y CEU Cardenal Herrera. Se han incluido presentaciones ppsx interactivas y micro-vídeos de prácticas reales, incluyendo aciertos y fallos más comunes. En una primera evaluación de su eficacia se han observado resultados muy positivos tanto en el grado de aceptación por los alumnos como por el profesorado. La herramienta diseñada no sólo permitirá una adaptación rápida de la docencia presencial a online, sino que podrá ser empleada para favorecer el aprendizaje presencial y para la formación de postgrado