Mechanism for ESCPE-1 mediated membrane remodelling and cargo selection in endosomal

iii, 159 p.El reciclaje de proteínas es fundamental para mantener la homeostasis celular. Este trabajo se enfoca en el reciclaje de proteínas que llegan a los endosomas. Allí, las proteínas transmembrana (receptores) son recicladas en un sistema de membranas tubulares (conocido como ¿tubular endosomal network¿) que emergen de los endosomas y se distribuyen por la célula, en concreto hacia el aparato de Golgi y la membrana plasmática. Usando un enfoque multidisciplinar que implica distintas técnicas bioquímicas y de biología estructural, hemos caracterizado uno de los complejos involucrados en la selección de proteínas a reciclar y la deformación de membranas. En concreto, usando cristalografía y difracción de rayos X, hemos resuelto parte de la estructura de este complejo. Por otro lado, diversas técnicas bioquímicas nos han servido para observar la interacción de dicho complejo con una de las proteínas que recicla. Por último, usando la última tecnología en microscopía electrónica (conocida como crio-tomografía electrónica y promedio del sub-tomograma, o "cryo-electron tomography and sub-tomogram averaging"), hemos visto cómo dicho complejo se sitúa en la membrana y es capaz de formar tubos a partir de vesículas artificiales, o liposomas. Nuestro trabajo ayuda a la comprensión de los mecanismos de reciclaje celular, contribuyen a entender el sistema de membranas que emerge de los endosomas

Pre-inflation from the multiverse: Can it solve the quadrupole problem in the cosmic microwave background?

We analyze a quantized toy model of a universe undergoing eternal inflation using a quantum-field-theoretical formulation of the Wheeler-DeWitt equation. This so-called third quantization method leads to the picture that the eternally inflating universe is converted to a multiverse in which sub-universes are created and exhibit a distinctive phase in their evolution before reaching an asymptotic de Sitter phase. From the perspective of one of these sub-universes, we can thus analyze the pre-inflationary phase that arises naturally. Assuming that our observable universe is represented by one of those sub-universes, we calculate how this pre-inflationary phase influences the power spectrum of the cosmic microwave background (CMB) anisotropies and analyze whether it can explain the observed discrepancy of the power spectrum on large scales, i.e. the quadrupole issue in the CMB. While the answer to this question is negative in the specific model analyzed here, we point out a possible resolution of this issue.Comment: 15 pages, 9 figures. Correction of typos, one figure added. Accepted for publication in European Physical Journal

Niche divergence and limits to expansion in the high polyploid Dianthus broteri complex

Niche evolution in plant polyploids remains controversial and evidence for alternative patterns has been reported. Using the autopolyploid Dianthus broteri complex (2×, 4×, 6× and 12×) as a model, we aimed to integrate three scenarios – competitive exclusion, recurrent origins of cytotypes and niche filling – into a single framework of polyploid niche evolution. We hypothesized that high polyploids would tend to evolve towards extreme niches when low ploidy cytotypes have nearly filled the niche space. We used several ecoinformatics and phylogenetic comparative analyses to quantify differences in the ecological niche of each cytotype and to evaluate alternative models of niche evolution. Each cytotype in this complex occupied a distinct ecological niche. The distributions were mainly constrained by soil characteristics, temperature and drought stress imposed by the Mediterranean climate. Tetraploids had the highest niche breadth and overlap due to their multiple origins, whereas the higher ploidy cytotypes were found in different, restricted, nonoverlapping niches. Niche evolution analyses suggested a scenario with one niche optimum for each ploidy, including the two independent tetraploid lineages.Our results suggest that the fate of nascent polyploids could not be predicted without accounting for phylogenetic relatedness, recurrent origins or the niche occupied by ancestors.Aridos La Melera S.L. (FIUS project 2234/0724

What if? - Exploring the Multiverse through Euclidean wormholes

We present Euclidean wormhole solutions describing possible bridges within the multiverse. The study is carried out in the framework of the third quantization. The matter content is modelled through a scalar field which supports the existence of a whole collection of universes. The instanton solutions describe Euclidean solutions that connect baby universes with asymptotically de Sitter universes. We compute the tunnelling probability of these processes. Considering the current bounds on the energy scale of inflation and assuming that all the baby universes are nucleated with the same probability, we draw some conclusions about what are the universes more likely to tunnel and therefore undergo a standard inflationary era.Comment: 12 pages, 5 figures. Explanations improved. Version accepted in EPJ