The discovery of CRISPR in archaea and bacteria

CRISPR-Cas are self-/nonself-discriminating systems found in prokaryotic cells. They represent a remarkable example of molecular memory that is hereditarily transmitted. Their discovery can be considered as one of the first fruits of the systematic exploration of prokaryotic genomes. Although this genomic feature was serendipitously discovered in molecular biology studies, it was the availability of multiple complete genomes that shed light about their role as a genetic immune system. Here we tell the story of how this discovery originated and was slowly and painstakingly advanced to the point of understating the biological role of what initially was just an odd genomic feature.FJMM is funded by the Spanish Ministerio de Economía y Competitividad (BIO2014-53029P) and the European Commission/Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (291815 Era-Net ANIHWA). FR-V is funded by projects MEDIMAX BFPU2013-48007-P from the Spanish Ministerio de Economía y Competitividad, MaCuMBA Project 311975 of the European Commission FP7 and PROMETEO II/2014/012 project AQUAMET from the Generalitat Valenciana

Infinite Factorial Finite State Machine for Blind Multiuser Channel Estimation

New communication standards need to deal with machine-to-machine communications, in which users may start or stop transmitting at any time in an asynchronous manner. Thus, the number of users is an unknown and time-varying parameter that needs to be accurately estimated in order to properly recover the symbols transmitted by all users in the system. In this paper, we address the problem of joint channel parameter and data estimation in a multiuser communication channel in which the number of transmitters is not known. For that purpose, we develop the infinite factorial finite state machine model, a Bayesian nonparametric model based on the Markov Indian buffet that allows for an unbounded number of transmitters with arbitrary channel length. We propose an inference algorithm that makes use of slice sampling and particle Gibbs with ancestor sampling. Our approach is fully blind as it does not require a prior channel estimation step, prior knowledge of the number of transmitters, or any signaling information. Our experimental results, loosely based on the LTE random access channel, show that the proposed approach can effectively recover the data-generating process for a wide range of scenarios, with varying number of transmitters, number of receivers, constellation order, channel length, and signal-to-noise ratio.Comment: 15 pages, 15 figure

Metodología didáctica para mejorar el rendimiento del alumnado dentro del aula en las unidades de dibujo técnico de ESO

El presente trabajo pretende dar respuesta a un bajo nivel de rendimiento por parte de los alumnos de la ESO, en las unidades didácticas de dibujo técnico, en la asignatura de Educación Plástica, Visual y Audiovisual. Observada esta carencia en el periodo de prácticas; se analiza en función de las motivaciones y carencias actuales dentro del aula, y se busca una solución aplicando técnicas actuales como el aula invertida, y la teoría del autoaprendizaje y el uso de las TICs para crear un clima de trabajo en el horario de clase, y fomentar el esfuerzo por parte del alumnado

Radiography of internet autonomous systems interconnection in Latin America and the Caribbean.

Lots of studies about the Internet Autonomous System (AS) level topology have been carried out during the last twenty years, most of them analyzing this topology on a world-wide scale, a lot of them based on routing information from the Border Gateway Protocol (BGP). However, studies focusing on a specific region and making comparisons between regions are not that popular and in fact, most world-wide studies are not valid in some particular regions. This work is targeting this particular problem of the regional or country topology analysis by enhancing regular AS-level graphs where to apply different connectivity metrics. The focus is set on Latin America and the Caribbean (the LAC region) which exhibits appropriate conditions for this type of analysis and where we show that a basic metric comparison may not be good enough so as to realize that there is a connectivity problem in the region. After concluding that the situation in the LAC region in terms of interconnection is even worse than expected, we perform some country-level studies finding correlations between graph characteristics and some socioeconomic indicators. We then use these correlations to identify countries in which it would be worth pushing for the deployment of an Internet Exchange Point (IXP), as simulating the creation of an IXP there has a great impact on the interconnection level and on the robustness of the regional Internet.The work done by Francisco Valera has been partially granted by the European Commission project LEONE (From local measurements to global management, grant number FP7-317647). The work done by Sofía Silva has been partially funded by IMDEA Networks.Publicad

Pangenome Evolution in theMarine Bacterium Alteromonas

Wehave examined a collection of the free-livingmarine bacterium Alteromonas genomeswith cores diverging in average nucleotide identities ranging from 99.98% to 73.35%, i.e., frommicrobes that can be consideredmembers of a natural clone (like in a clinical epidemiological outbreak) to borderline genus level. The genomes were largely syntenic allowing a precise delimitation of the core and flexible regions in each. The core was 1.4Mb (ca. 30% of the typical strain genome size). Recombination rates along the core were high among strains belonging to the same species (37.7–83.7% of all nucleotide polymorphisms) but they decreased sharply between species (18.9–5.1%). Regarding the flexible genome, itsmain expansion occurred within the boundaries of the species, i.e., strains of the same species already have a large and diverse flexible genome. Flexible regions occupy mostly fixed genomic locations. Four large genomic islands are involved in the synthesis of strain-specific glycosydic receptors that we have called glycotypes. These genomic regions are exchanged by homologous recombination within and between species and there is evidence for their import from distant taxonomic units (other genera within the family). In addition, several hotspots for integration of gene cassettes by illegitimate recombination are distributed throughout the genome. They code for features that give each clone specific properties to interact with their ecological niche andmustflowfast throughout thewholegenus as they are found, withnearly identical sequences, in different species. Models for the generation of this genomic diversity involving phage predation are discussed.This work was funded by the Spanish MINECO (Grants BFPU2013-48007-P)This work was funded by the Generalitat Valenciana PROMETEO (Grants II/2014/012

Light as an energy source in continuous cultures of bacteriorhodopsin-containing halobacteria

The role of light as an energy source for slightly aereated cultures of halobac­ teria was studied, using continuous cultures with low nutrient concentrations and a low oxygen supply. A series of experiments were carried out with non­ illuminated and differently illuminated cultures and with ditferent oxygen transfer rates. Under low oxygen availability, light proved to be a decisively important energy source that allowed the populations to reach higher growth rates and much higher population densities. Oxygen inftuenced the growth over only a minimal level, below which neither the illuminated nor the dark cultures were atfected by the oxygen transfer rate. From these results, it appears that the bacteriorhodop­ sin-mediated energy supply could have a very important role for the ecology of halobacteria in their microaerophilic habitats. In the illuminated cultures, cells that originated purple colonies on plates appeared. These cells, which could be bacteriorhodopsin-constitutive mutants, are now being studied

Thermography and Sonic Anemometry to Analyze Air Heaters in Mediterranean Greenhouses

The present work has developed a methodology based on thermography and sonic anemometry for studying the microclimate in Mediterranean greenhouses equipped with air heaters and polyethylene distribution ducts to distribute the warm air. Sonic anemometry allows us to identify the airflow pattern generated by the heaters and to analyze the temperature distribution inside the greenhouse, while thermography provides accurate crop temperature data. Air distribution by means of perforated polyethylene ducts at ground level, widely used in Mediterranean-type greenhouses, can generate heterogeneous temperature distributions inside the greenhouse when the system is not correctly designed. The system analyzed in this work used a polyethylene duct with a row of hot air outlet holes (all of equal diameter) that expel warm air toward the ground to avoid plant damage. We have observed that this design (the most widely used in Almería’s greenhouses) produces stagnation of hot air in the highest part of the structure, reducing the heating of the crop zone. Using 88 kW heating power (146.7 W∙m−2) the temperature inside the greenhouse is maintained 7.2 to 11.2 °C above the outside temperature. The crop temperature (17.6 to 19.9 °C) was maintained above the minimum recommended value of 10 °C

IMS signalling for multiparty services based on network level multicast

3rd EURO-NGI Conference on Next Generation Internet Networks. Norwegian University of Science and Technology, Trondheim, Norway, 21-23 may 2007.The standardization process of the UMTS technology has led to the development of the IP Multimedia Subsystem (IMS). IMS provides a framework that supports the negotiation of the next generation multimedia services with QoS requirements that are envisioned for 3G networks. But even though many of these services involve the participation of multiple users in a multiparty arrangement, the delivery technology at network level is still unicast based. This approach is not optimum, in terms of transmission efficiency. In this paper, a new approach is presented proposing to use a network level multicast delivery technology for the multiparty services that are signalled through IMS. The main advantages and drawbacks related with this new approach are analyzed in the article. Finally, as a starting point in the development of the presented solution, a new SIP signalling dialogue is proposed allowing the negotiation of a generic multiparty service, and supporting at the same time the configuration of the corresponding network level multicast delivery service with QoS requirements that will be used in the user plane.Publicad

Explaining microbial population genomics through phage predation

The remarkable diversity of genes within the pool of prokaryotic genomes belonging to the same species or pan-genome is difficult to reconcile with the widely accepted paradigm which asserts that periodic selection within bacterial populations would regularly purge genomic diversity by clonal replacement. Recent evidence from metagenomics indicates that even within a single sample a large diversity of genomes can be present for a single species. We have found that much of the differential gene content affects regions that are potential phage recognition targets. We therefore propose the operation of Constant-Diversity dynamics in which the diversity of prokaryotic populations is preserved by phage predation. We provide supporting evidence for this model from metagenomics, mathematical analysis and computer simulations. Periodic selection and phage predation dynamics are not mutually exclusive; we compare their predictions to indicate under which ecological circumstances each dynamics could predominate