Alpha-synuclein (α-syn) is localized in cellular organelles of most neurons, but many of its physiological functions are only partially understood. α-syn accumulation is associated with Parkinson's ...disease, dementia with Lewy bodies, and multiple system atrophy as well as other synucleinopathies; however, the exact pathomechanisms that underlie these neurodegenerative diseases remain elusive. In this review, we describe what is known about α-syn function and pathophysiological changes in different cellular structures and organelles, including what is known about its behavior as a prion-like protein. We summarize current knowledge of α-syn and its pathological forms, covering its effect on each organelle, including aggregation and toxicity in different model systems, with special interest on the mitochondria due to its relevance during the apoptotic process of dopaminergic neurons. Moreover, we explore the effect that α-syn exerts by interacting with chromatin remodeling proteins that add or remove histone marks, up-regulate its own expression, and resume the impairment that α-syn induces in vesicular traffic by interacting with the endoplasmic reticulum. We then recapitulate the events that lead to Golgi apparatus fragmentation, caused by the presence of α-syn. Finally, we report the recent findings about the accumulation of α-syn, indirectly produced by the endolysosomal system. In conclusion, many important steps into the understanding of α-syn have been made using
and
models; however, the time is right to start integrating observational studies with mechanistic models of α-syn interactions, in order to look at a more complete picture of the pathophysiological processes underlying α-synucleinopathies.
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•Dispersal of alien species is a global problem threatening native biodiversity.•The microsymbiotic community was rich in native amphipods and poor in invasive hosts.•Host species and ...locality are key drivers shaping the structure of microsymbionts.•Habitat condition was a stronger determinant of richness than geographic distance.•Random distribution of microsymbiotic species richness was common in gammarids.
Dispersal of alien species is a global problem threatening native biodiversity. Co-introduction of non-native parasites and pathogens adds to the severity of this threat, but this indirect impact has received less attention. To shed light on the key factors determining the richness of microorganisms in native and invasive host species, we compared symbiotic (parasitic and epibiotic) communities of gammarids across different habitats and localities along the Baltic coast of Poland. Seven gammarid species, two native and five invasive, were sampled from 16 freshwater and brackish localities. Sixty symbiotic species of microorganisms of nine phyla were identified. This taxonomically diverse species assemblage of symbionts allowed us to assess the effect of host translocation and regional ecological determinants driving assembly richness in the gammarid hosts. Our results revealed that (i) the current assemblages of symbionts of gammarid hosts in the Baltic region are formed by native and co-introduced species; (ii) species richness of the symbiotic community was higher in the native Gammarus pulex than in the invasive hosts, probably reflecting a process of species loss by invasive gammarids in the new area and the distinct habitat conditions occupied by G. pulex and invasive hosts; (iii) both host species and locality were key drivers shaping assembly composition of symbionts, whereas habitat condition (freshwater versus brackish) was a stronger determinant of communities than geographic distance; (iv) the dispersion patterns of the individual species richness of symbiotic communities were best described by Poisson distributions; in the case of an invasive host, the dispersion of the rich species diversity may switch to a right-skewed negative binomial distribution, suggesting a host-mediated regulation process. We believe this is the first analysis of the symbiotic species richness in native and invasive gammarid hosts in European waters based on original field data and a broad range of taxonomic groups including Microsporidia, Choanozoa, Ciliophora, Apicomplexa, Platyhelminthes, Nematoda, Nematomorha, Acanthocephala and Rotifera, to document the patterns of species composition and distribution.
An important question in the study of phenotypic evolution is whether characters are independent of each other or behave and evolve as integrated modules. Morphological integration and modularity ...provide a powerful framework for the analysis of the evolution of morphological traits. We used geometric morphometrics and phylogenetically independent contrasts (PIC) to test four different modularity hypotheses in the haptoral anchors of 14 monogenean species of
Ligophorus
. Integration between the modular units identified was further evaluated with two-block partial least squares analysis. Roots and points represented two modules in the dorsal and ventral anchors, but modularity was not statistically supported when parasite phylogeny was accounted for, which may indicate convergent evolution related to host characteristics and gill morphology. In contrast, PIC revealed medial and lateral modules in ventral anchors only. Moreover, we found evidence for ventral and dorsal anchor pairs forming two modules, supporting the notion that they play different functional roles. Integration between all identified modules was strong. We conclude that there is modular structure in the anchors of
Ligophorus
spp., accounted by adaptive and phylogenetic factors acting at different levels, and ventral and dorsal anchors evolve as integrated modules with specific roles in attachment.
Photocatalytic activity of TiO2 was studied in two types of calcium aluminate cement (CAC) under two different curing regimes. The effect of the TiO2 addition on the setting time, consistency and ...mechanical properties of the CACs was evaluated. The abatement of gaseous pollutants (NOx) under UV irradiation was also assessed. These cementitious matrices were found to successfully retain NO2: more abundant presence of aluminates in white cement (w-CAC, iron-lean) helped to better adsorb NO2, thus improving the conversion performance of the catalyst resulting in a larger NOx removal under UV irradiation. As evidenced by XRD, SEM, EDAX and zeta potential analyses, the presence of ferrite in dark cement (d-CAC, iron-reach) induced a certain chemical interaction with TiO2. The experimental findings suggest the formation of new iron titanate phases, namely pseudobrookite. The reduced band-gap energy of these compounds compared with that of TiO2 accounts for the photocatalytic activity of these samples.
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A method based on object kinetic Monte Carlo that can account for segregation and precipitation in metallic alloys in the presence of both vacancies and self-interstitials is ...presented. Here the model has been applied specifically to FeCr alloys, but could be used for other alloys with proper parametrization. The model is based on the division of the simulation box into cells where only the local concentration of the alloy is considered and not the explicit location of each alloy atom, in a mean field type of approach. This concentration, together with those of neighboring cells, is used to bias defect migration taking into account the proper thermodynamics of the alloy at hand and the stiffness coefficient to include neighboring effects. The novelty of this implementation is, among other things, the explicit description of mixed pairs of point defects with the alloy element: vacancy-Cr (VCr) and self-interstitial-Cr (ICr) whenever necessary. This explicit description allows the temperature dependence of defect evolution to be correctly reproduced. In this paper we present the model in detail for the particular case of processes that take place in the presence of vacancies, to show the robustness and applicability of this method.
•A precipitation reduced scenario did not affect soil respiration rates.•Plant cover type of a semiarid grassland imposed differences in soil respiration.•Soil water content was the main driver of ...soil respiration rates.•Grasslands conserving the key species were less sensitive to environmental changes.
Examination of the effects of altered precipitation and atmospheric temperature patterns on ecosystem processes are an active area of research. Influences of these climate factors may change when plant cover and species composition are disturbed as a consequence of land use change altering ecosystem processes, such as soil respiration. We addressed the following question: how does experimentally manipulated reduction in the size of each precipitation event influence soil respiration fluxes (Rs) in a tropical semiarid grassland with different plant cover and species composition? Rainout shelters were installed over eight yr old planted monospecific plots (4m2) of Bouteloua gracilis, the keystone species of the grassland biome, and over mixed grassland plots in sites that recovered from abandoned agricultural land, allowing full or a 50% reduction of ambient precipitation. Soil respiration rates as well soil temperature (Tsoil) and soil water content (SWC), as controlling factors, were monitored. Overall, SWC was the most important control for Rs explaining ∼70% of its variability, followed by Tsoil which explained ∼25% and plant cover type having a minor effect (3%) explaining Rs variability. Still, Rs exhibited differential responses when comparing plant cover types; SWC in the mixed grassland had up to 90% relative influence on Rs as compared to 10% by Tsoil. In contrast, Rs rates in monospecific B. gracilis plots exhibited less overall variability considering SWC (55–60%) and Tsoil (40–45%), suggesting that grasslands dominated by the keystone species are more resilient and better buffer the effects of extreme climatic drought conditions on ecosystem processes.
3D double sided detector fabrication at IMB-CNM Pellegrini, G.; Balbuena, J.P.; Bassignana, D. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
01/2013, Volume:
699
Journal Article
Peer reviewed
Open access
The Large Hadron Collider (LHC) recorded its first collisions during the last months of 2009. By 2020 a two-stage upgrade of the accelerator complex, the High Luminosity LHC (HL-LHC), will increase ...the instantaneous luminosities up to a factor of ten compared to the current design. The particle fluxes at ATLAS will increment substantially with special impact on the inner tracking detector which will be subjected to large occupancies and radiation damage. In order to cope with the higher instantaneous luminosities ATLAS will upgrade its current Inner Detector (ID) in two phases, first by introducing a new pixel layer (IBL) mounted directly on the beam pipe, and later by completely replacing the current ID with several layers of semiconductor detectors (pixels and strips). The upgrades to the ATLAS ID require the development of new silicon technologies, since the current planar pixel sensors are not suitable for the expected radiation doses at small radii. For these inner detector layers, the most promising technology is the so-called 3D sensor, while improved planar sensors are considered for the external layers. Silicon detectors with cylindrical electrodes offer advantages over standard planar sensors mainly because they are more radiation hard. 3D detectors with the double sided geometry have been fabricated at IMB-CNM clean room facilities. The layouts fits the new pixelated readout chip FE-I4 developed by the ATLAS collaboration.
Semiarid grasslands are water‐limited ecosystems where precipitation (PPT) controls the onset and duration of the growing season; however, this variable does not fully explain interannual variability ...of productivity at temporal scales. We examined the relationship between PPT and carbon (C) fluxes in a semiarid grassland at both seasonal and interannual scales, as well as the role of lagged effects of PPT and asymmetric sensitivities of net ecosystem carbon exchange to PPT and its components (gross ecosystem exchange GEE and ecosystem respiration ER). Six years of continuous net ecosystem C exchange data measured with the eddy covariance technique and GEE estimated with 15 years of enhanced vegetation index and the gross primary productivity of Moderate Resolution Imaging Spectroradiometer were used. The semiarid grassland was a C source and a C sink among contrasting PPT years (114 to −107 g C·m−2·year−1). At seasonal scale, PPT relationship with the 15 years of GEE derived from enhanced vegetation index and gross primary productivity was sigmoidal. Moreover, PPT legacies of the previous dry season determined the C balance of the grassland by affecting the C uptake and ecosystem respiration of the following growing season, but productivity was more sensitive to PPT changes than respiration. Models of climate change for semiarid grasslands in North America predict up to 30% reduction of winter‐spring PPT and slight summer PPT decrease. Thus, our results suggest that future changes in PPT may have a strong impact on the C uptake capacity of this ecosystem due to weakened legacy effects in summer C uptake.
Resumen
Los pastizales semiáridos son ecosistemas deficientes en agua, en donde la precipitación (PPT) controla tanto el inicio como la duración de la estación de crecimiento; a pesar de eso, la precipitación no puede explicar en su totalidad la variabilidad interanual de su productividad. En este estudio, examinamos la relación entre PPT y los flujos de carbono (C) de un pastizal semiárido a escalas estacionales e interanuales, así como el papel de efectos de legado de la precipitación y la sensibilidad asimétrica del intercambio de carbono neto del ecosistema (NEE) y sus componentes (intercambio neto del ecosistema (GEE) y respiracién del ecosistema (ER)). Se emplearon seis años de datos continuos de NEE obtenidos por medio de la técnica de flujos turbulentos covariados y GEE estimados con 15 años de índice mejorado de la vegetación así como la productividad primaria bruta derivada de las imágenes del espectro radiómetro de resolución moderada. El pastizal semiárido funcionó como un almacén o una fuente de C entre años contrastantes de precipitación (114 to –107 g C•m–2•year–1). A escalas estacionales, la relación de PPT con el GEE derivado de 15 años de índice mejorado de la vegetación, así como con la producción primaria bruta fueron de tipo sigmoidal. Además, los legados de la PPT de la temporada de estiaje definió el balance de C del pastizal en la temporada de crecimiento siguiente a través de sus efectos en la asimilación de C y respiración del ecosistema, resultando la productividad más sensible a los cambios de precipitación que la respiración. Los modelos de cambio climático para el pastizal semiárido en Norte América predicen un decremento hasta del 30% de la precipitación durante el estiaje (invierno/primavera) mientras el declive de PPT en el verano será mucho menor. De esta manera, nuestros resultados sugieren que cambios futuros de la PPT tendrán un fuerte impacto en la capacidad de asimilación de C en el pastizal semiárido, debido a un efecto de legado debilitado para la asimilación de C en el verano.
Plain language summary
Precipitation is the main driver of productivity in semiarid ecosystems; however, annual precipitation does not fully explain interannual variability of productivity. Semiarid grasslands influenced by monsoonal precipitation regimes exhibit 6 to 8 months of drought with less than 20% of annual precipitation. This small amount of rain when vegetation is dormant would seem to be unimportant in terms of imposing control on productivity or carbon (C) fluxes. Using ecosystem flux data, we tested whether this small precipitation amount in the dry season had a role in controlling C fluxes and productivity and how much this affects the annual C uptake. We demonstrated for a semiarid grassland with summer prevailing rains that the small dry‐season precipitation highly determines the carbon balance of both the humid growing season and the annual C balance. Also, we found that dry seasons with large amounts of precipitation enhanced productivity more than ecosystem respiration in summer. Our study highlights the importance of the dry‐season precipitation on the productivity of semiarid grasslands where it is forecasted a greater proportion of precipitation reduction for winter than for summer at the end of this century. In this sense, our study highlights possible impacts of climate change on the vulnerability of semiarid ecosystems.
Key Points
We examined the lagged effects of precipitation, as this factor may explain interannual variability of carbon flux in semiarid grasslands
Dry‐season precipitation exerted larger effects on gross ecosystem productivity than ecosystem respiration in the following growing season
Semiarid grasslands of central Mexico are likely to be carbon sources in the face of drier winters predicted at the end of this century
We applied a combined molecular and morphological approach to resolve the taxonomic status of Saccocoelium spp. parasitizing sympatric mullets (Mugilidae) in the Mediterranean. Eight morphotypes of ...Saccocoelium were distinguished by means of multivariate statistical analyses: 2 of Saccocoelium obesum ex Liza spp.; 4 of S. tensum ex Liza spp.; and 2 (S. cephali and Saccocoelium sp.) ex Mugil cephalus. Sequences of the 28S and ITS2 rRNA gene regions were obtained for a total of 21 isolates of these morphotypes. Combining sequence data analysis with a detailed morphological and multivariate morphometric study of the specimens allowed the demonstration of cryptic diversity thus rejecting the hypothesis of a single species of Saccocoelium infecting sympatric mullets in the Mediterranean. Comparative sequence analysis revealed 4 unique genotypes, thus corroborating the distinct species status of Saccocoelium obesum, S. tensum and S. cephali and a new cryptic species ex Liza aurata and L. saliens recognized by its consistent morphological differentiation and genetic divergence. However, in spite of their sharp morphological difference the 2 morphotypes from M. cephalus showed no molecular differentiation and 4 morphotypes of S. tensum were genetically identical. This wide intraspecific morphological variation within S. tensum and S. cephali suggests that delimiting species of Saccocoelium using solely morphological criteria will be misleading.
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