Ruiz-Mirazo K.,University of the Basque Country |
Briones C.,CSIC - National Institute of Aerospace Technology |
De La Escosura A.,Autonomous University of Madrid
Chemical Reviews | Year: 2014
In order to explain how the first organisms might have appeared on Earth, or elsewhere, it is necessary to develop chemistries that enable the synthesis of information-bearing polymers, protometabolic networks, and protocellular compartments under compatible prebiotic conditions. In this direction, the first step would be the synthesis of the monomeric units that constitute peptides, nucleic acids or their analogue polymers, and vesicle membranes. Some of these building blocks could have been delivered to Earth from extraterrestrial sources, while their endogenous synthesis on our planet is another feasible option. Catalysis, in particular organocatalysis and organometallic catalysis, could have enlarged and diversified the set of compounds potentially present in different prebiotic scenarios. Vesicles composed of mixtures of simple amphiphilic molecules and surfactants, on the other hand, have shown the required stability and permeability for encapsulation of nucleic acids and peptides.
Alves J.,University of Vienna |
Bouy H.,CSIC - National Institute of Aerospace Technology
Astronomy and Astrophysics | Year: 2012
Aims. The aim of this work is to characterize the stellar population between Earth and the Orion A molecular cloud where the well-known star formation benchmark Orion nebula cluster (ONC) is embedded. Methods. We used the denser regions the Orion A cloud to block optical background light, effectively isolating the stellar population in front of it. We then used a multi-wavelength observational approach to characterize the cloud's foreground stellar population. Results. We find that there is a rich stellar population in front of the Orion A cloud, from B-stars to M-stars, with a distinct 1) spatial distribution; 2) luminosity function; and 3) velocity dispersion from the reddened population inside the Orion A cloud. The spatial distribution of this population peaks strongly around NGC 1980 (iota Ori) and is, in all likelihood, the extended stellar content of this poorly studied cluster. We infer an age of ∼4-5 Myr for NGC 1980 and estimate a cluster population of about 2000 stars, which makes it one of the most massive clusters in the entire Orion complex. This newly found population overlaps significantly with what is currently assumed to be the ONC and the L1641N populations, and can make up for more than 10-20% of the ONC population (30-60% if the Trapezium cluster is excluded from consideration). What is currently taken in the literature as the ONC is then a mix of several intrinsically different populations, namely 1) the youngest population, including the Trapezium cluster and ongoing star formation in the dense gas inside the nebula; 2) the foreground population, dominated by the NGC 1980 cluster; and 3) the poorly constrained population of foreground and background Galactic field stars. Conclusions. Our results support a scenario where the ONC and L1641N are not directly associated with NGC 1980, i.e., they are not the same population emerging from its parental cloud, but are instead distinct overlapping populations. The nearest massive star formation region and the template for massive star-and cluster formation models is then substantially contaminated by the foreground stellar population of the massive NGC 1980 cluster, formed about 4-5 Myr ago in a different, but perhaps related, event in the larger Orion star formation complex. This result calls for a revision of most of the observables in the benchmark ONC region (e.g., ages, age spread, cluster size, mass function, disk frequency, etc.). © 2012 ESO.
Mendez J.,CSIC - Institute of Materials Science |
Lopez M.F.,CSIC - Institute of Materials Science |
Martin-Gago J.A.,CSIC - Institute of Materials Science |
Martin-Gago J.A.,CSIC - National Institute of Aerospace Technology
Chemical Society Reviews | Year: 2011
Creating or connecting together large organic molecules, as polycyclic aromatic hydrocarbons (PAH), by chemical reactions readily on surfaces is the first step to a true advance in the field of molecular electronics. On-surface synthesis can be regarded as an efficient means to build new molecular species by using bottom-up strategies. Recently, a collection of different reactions leading to large tailor-made organic molecules on single-crystal metal surfaces has been reported. The fundamental mechanisms controlling these reactions can be investigated from a surface science perspective. This discipline skillfully combines the use of characterization techniques at the nanoscale, with single-crystal metallic surfaces able to catalyse these reactions. We present a tutorial review that highlights the relevance of the new bottom up strategies and classifies most of the different molecular on-surface reactions involving aromatic organic molecules that have been published up to date. © 2011 The Royal Society of Chemistry.
Smith A.B.,Natural History Museum in London |
Zamora S.,Natural History Museum in London |
Alvaro J.J.,CSIC - National Institute of Aerospace Technology
Nature Communications | Year: 2013
The earliest fossil echinoderms have, until now, come almost exclusively from North America and are represented by few taxa, all of which have a radiate body plan. Here we report the discovery of two new echinoderm faunas from the early part of the Cambrian of Morocco (West Gondwana). The former represents the oldest echinoderm fauna from Gondwana, approximately equivalent in age to those from North America, and the latter the oldest diversified fauna from Gondwana. In both cases, the appearance of well-preserved echinoderms coincides with a change in palaeogeographic regime. The presence of four markedly different echinoderm body plans in these earliest faunas indicates that considerable diversification had already taken place by 510 Ma. Yet all share the same distinctive biomineralized skeleton that, based on the fossil record and ocean geochemistry, probably evolved just 10-15 my earlier. This suggests that a rapid rate of morphological divergence took place during the initial stages of echinoderm evolution. © 2013 Macmillan Publishers Limited. All rights reserved.
Gonzalez-Pastor J.E.,CSIC - National Institute of Aerospace Technology
FEMS Microbiology Reviews | Year: 2011
A social behavior named cannibalism has been described during the early stages of sporulation of the Gram-positive Bacillus subtilis. This phenomenon is based on the heterogeneity of sporulating populations, constituted by at least two cell types: (1) sporulating cells, in which the master regulator of sporulation Spo0A is active, and (2) nonsporulating cells, in which Spo0A is inactive. Sporulating cells produce two toxins that act cooperatively to kill the nonsporulating sister cells. The nutrients released by the dead cells into the starved medium are used for growth by the sporulating cells that are not yet fully committed to sporulate, and as a result, sporulation is arrested. This review outlines the molecular mechanisms of the killing and immunity to the toxins, the regulation of their production and other examples of killing of siblings in microorganisms. The biological significance of this behavior is discussed. © 2010 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd.