Mitochondrial echoes of first settlement and genetic continuity in El Salvador

Background: From Paleo-Indian times to recent historical episodes, the Mesoamerican isthmus played an important role in the distribution and patterns of variability all around the double American continent. However, the amount of genetic information currently available on Central American continental populations is very scarce. In order to shed light on the role of Mesoamerica in the peopling of the New World, the present study focuses on the analysis of the mtDNA variation in a population sample from El Salvador. Methodology/Principal Findings: We have carried out DNA sequencing of the entire control region of the mitochondrial DNA (mtDNA) genome in 90 individuals from El Salvador. We have also compiled more than 3,985 control region profiles from the public domain and the literature in order to carry out inter-population comparisons. The results reveal a predominant Native American component in this region: by far, the most prevalent mtDNA haplogroup in this country (at ~90%) is A2, in contrast with other North, Meso- and South American populations. Haplogroup A2 shows a star-like phylogeny and is very diverse with a substantial proportion of mtDNAs (45%; sequence range 16090–16365) still unobserved in other American populations. Two different Bayesian approaches used to estimate admixture proportions in El Salvador shows that the majority of the mtDNAs observed come from North America. A preliminary founder analysis indicates that the settlement of El Salvador occurred about 13,400±5,200 Y.B.P.. The founder age of A2 in El Salvador is close to the overall age of A2 in America, which suggests that the colonization of this region occurred within a few thousand years of the initial expansion into the Americas. Conclusions/Significance: As a whole, the results are compatible with the hypothesis that today's A2 variability in El Salvador represents to a large extent the indigenous component of the region. Concordant with this hypothesis is also the observation of a very limited contribution from European and African women (~5%). This implies that the Atlantic slave trade had a very small demographic impact in El Salvador in contrast to its transformation of the gene pool in neighbouring populations from the Caribbean facade

Localization and broadband follow-up of the gravitational-wave transient GW150914

A gravitational-wave (GW) transient was identified in data recorded by the Advanced Laser Interferometer Gravitational-wave Observatory (LIGO) detectors on 2015 September 14. The event, initially designated G184098 and later given the name GW150914, is described in detail elsewhere. By prior arrangement, preliminary estimates of the time, significance, and sky location of the event were shared with 63 teams of observers covering radio, optical, near-infrared, X-ray, and gamma-ray wavelengths with ground- and space-based facilities. In this Letter we describe the low-latency analysis of the GW data and present the sky localization of the first observed compact binary merger. We summarize the follow-up observations reported by 25 teams via private Gamma-ray Coordinates Network circulars, giving an overview of the participating facilities, the GW sky localization coverage, the timeline, and depth of the observations. As this event turned out to be a binary black hole merger, there is little expectation of a detectable electromagnetic (EM) signature. Nevertheless, this first broadband campaign to search for a counterpart of an Advanced LIGO source represents a milestone and highlights the broad capabilities of the transient astronomy community and the observing strategies that have been developed to pursue neutron star binary merger events. Detailed investigations of the EM data and results of the EM follow-up campaign are being disseminated in papers by the individual teams

Localization and broadband follow-up of the gravitational-wave transient GW150914

A gravitational-wave transient was identified in data recorded by the Advanced LIGO detectors on 2015 September 14. The event candidate, initially designated G184098 and later given the name GW150914, is described in detail elsewhere. By prior arrangement, preliminary estimates of the time, significance, and sky location of the event were shared with 63 teams of observers covering radio, optical, near-infrared, X-ray, and gamma-ray wavelengths with ground- and space-based facilities. In this Letter we describe the low-latency analysis of the gravitational wave data and present the sky localization of the first observed compact binary merger. We summarize the follow-up observations reported by 25 teams via private Gamma-ray Coordinates Network Circulars, giving an overview of the participating facilities, the gravitational wave sky localization coverage, the timeline and depth of the observations. As this event turned out to be a binary black hole merger, there is little expectation of a detectable electromagnetic signature. Nevertheless, this first broadband campaign to search for a counterpart of an Advanced LIGO source represents a milestone and highlights the broad capabilities of the transient astronomy community and the observing strategies that have been developed to pursue neutron star binary merger events. Detailed investigations of the electromagnetic data and results of the electromagnetic follow-up campaign will be disseminated in the papers of the individual teams

Book 7 of Ibn al-Nafīs’s commentary on the Hippocratic Aphorisms

The interest in plant virus evolution can be dated to the late 1920s, when it was shown that plant virus populations were genetically heterogeneous, and that Ihcir composition changed according to the experimental conditions. Many important ideas were generated prior to the era of molecular virology, such as the role of hostand vector-associated selection in virus evolution, and also that small populations, gene coadaptation and evolutionary trade-offs could limit the efficiency of selection. The analysis of viral genomes in the 1980s and 1990s established the quasispecieslike structure of their populations and allowed extensive analyses of the relationships among vims strains and species. The concept that vims populations had huge sizes and high rates of adaptive mutations became prevalent in this period, with selection mostly invoked as explaining observed patterns of population structure and evolution. In recent times vims evolution has been coming into line with evolutionary biology, and a more complex scenario has emerged. Population bottlenecks during host colonization, during host-to-host transmission or during host population fluctuations may result in smaller population sizes, and genetic drift has been recognized as an important evolutionary factor. Also, particularities of viral genomes such as low levels of neutrality, multifunctionality of coding and encoded sequences or strong epistasis could constrain the plasticity of viral genomes and hinder their response to selection. Exploring the complexities of plant vims evolution will continue to be a challenge for the future, particularly as it affects host, vector and ecosystem dynamics

Effects of various polyolefin copolymers on the interfacial interaction, microstructure and physical properties of cyclic olefin copolymer(COC)/graphite composites

In this study, effects of various types of functional polyolefin copolymers (FPOCs), poly(isobutylene-alt-maleic anhydride), poly(maleic anhydride-alt-1-octadecene) and poly(ethylene-graft-maleic anhydride), on the microstructure formation, interfacial interaction and physical properties of cyclic olefin copolymer (COC)/graphite composites were investigated. The COC/graphite composites were prepared in a lab. scale twin screw extruder. Microstructural features of samples were studied in a field emission scanning electron microscopy (FESEM). Viscoelastic properties of samples, obtained from the rheology tests in melt state and the dynamic mechanical analysis in solid state were used to quantify interfacial interactions between the COC and graphite depending on the types of FPOC. The average aspect ratio (A(f)) values of graphite flakes in the COC phase were determined about 40-65 by SEM observation and image analysis study on the samples prepared with different types of FPOC. Based on the gas permeability measurements, tortuous diffusion model suggested that the A(f) values of graphite flakes varied between 40 and 80 depending on the amount of graphite. It was shown that the poly(isobutylene-alt-maleic anhydride) copolymer provided relatively higher interfacial interaction between the COC and graphite flakes than the other FPOCs

Caveolae as plasma membrane sensors, protectors and organizers

Caveolae are submicroscopic, plasma membrane pits that are abundant in many mammalian cell types. The past few years have seen a quantum leap in our understanding of the formation, dynamics and functions of these enigmatic structures. Caveolae have now emerged as vital plasma membrane sensors that can respond to plasma membrane stresses and remodel the extracellular environment. Caveolae at the plasma membrane can be removed by endocytosis to regulate their surface density or can be disassembled and their structural components degraded. Coat proteins, called cavins, work together with caveolins to regulate the formation of caveolae but also have the potential to dynamically transmit signals that originate in caveolae to various cellular destinations. The importance of caveolae as protective elements in the plasma membrane, and as membrane organizers and sensors, is highlighted by links between caveolae dysfunction and human diseases, including muscular dystrophies and cancer