1,008 research outputs found

    A new and morphologically distinct population of cavernicolous Poecilia mexicana (Poeciliidae: Teleostei)

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    The cave molly, Poecilia mexicana, from the Cueva del Azufre, a sulfur cave in Tabasco, Mexico, ranks among the best-studied cave fishes worldwide, despite being known from a single population only. Here we describe a newly discovered second population of cave-dwelling P. mexicana from a nearby, but mostly non-sulfidic cave (Luna Azufre). Despite apparent similarities between the two populations (such as reduced eye diameter and reduced pigmentation), a geometric morphometric analysis revealed pronounced morphological differentiation between the two cave form

    Sex-specific local life-history adaptation in surface- and cave-dwelling Atlantic mollies (Poecilia mexicana)

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    Cavefishes have long been used as model organisms showcasing adaptive diversification, but does adaptation to caves also facilitate the evolution of reproductive isolation from surface ancestors? We raised offspring of wild-caught surface- and cave-dwelling ecotypes of the neotropical fish Poecilia mexicana to sexual maturity in a 12-month common garden experiment. Fish were raised under one of two food regimes (high vs. low), and this was crossed with differences in lighting conditions (permanent darkness vs. 12:12 h light:dark cycle) in a 2 × 2 factorial design, allowing us to elucidate potential patterns of local adaptation in life histories. Our results reveal a pattern of sex-specific local life-history adaptation: Surface molly females had the highest fitness in the treatment best resembling their habitat of origin (high food and a light:dark cycle), and suffered from almost complete reproductive failure in darkness, while cave molly females were not similarly affected in any treatment. Males of both ecotypes, on the other hand, showed only weak evidence for local adaptation. Nonetheless, local life-history adaptation in females likely contributes to ecological diversification in this system and other cave animals, further supporting the role of local adaptation due to strong divergent selection as a major force in ecological speciation

    A simple genetic basis of adaptation to a novel thermal environment results in complex metabolic rewiring in Drosophila

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    BACKGROUND:Population genetic theory predicts that rapid adaptation is largely driven by complex traits encoded by many loci of small effect. Because large-effect loci are quickly fixed in natural populations, they should not contribute much to rapid adaptation. RESULTS:To investigate the genetic architecture of thermal adaptation - a highly complex trait - we performed experimental evolution on a natural Drosophila simulans population. Transcriptome and respiration measurements reveal extensive metabolic rewiring after only approximately 60 generations in a hot environment. Analysis of genome-wide polymorphisms identifies two interacting selection targets, Sestrin and SNF4Aγ, pointing to AMPK, a central metabolic switch, as a key factor for thermal adaptation. CONCLUSIONS:Our results demonstrate that large-effect loci segregating at intermediate allele frequencies can allow natural populations to rapidly respond to selection. Because SNF4Aγ also exhibits clinal variation in various Drosophila species, we suggest that this large-effect polymorphism is maintained by temporal and spatial temperature variation in natural environments.François Mallard, Viola Nolte, Ray Tobler, Martin Kapun and Christian Schlöttere

    Overexpression of the p73 gene is a novel finding in high-risk B-cell chronic lymphocytic leukemia

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    The p73 protein shares structural and functional similarities with the tumour-suppressor p53, but its role in neoplastic transformation is unknown. Alternative splicing leads to the expression of at least nine p73 C-terminal mRNA splice variants (α β γ δ ε ξ η ηl θ). In this survey, we analyse the expression of p73 by real-time quantitative RT-PCR, its known C-terminal variants with an RT-PCR-Southern tech nique and by Western blot in samples of 51 patients with B-CLL, normal B lymphocytes from eight individuals, and five haematopoetic cell lines. p73α protein expression positively correlated with higher risk B-CLL stages (P=0.046). Total p73 mRNA expression was higher (P= 0.01) and p73α protein more frequently detected (P=0.008) in B-CLL compared with normal CD19+—B-lymphocytes. p73 C-terminal mRNA variants were expressed both in B-CLL and in normal B-lymphocytes, but their expression was biased since the γ (P=0.041), the θ (P ≪ 0.001), and the η variant (P=0.033) prevailed in normal B-lymphocytes. In summary, we conclude that the accumulation of p73, the expression pattern of particular p73 variants and its link to progression may play a distinct role in the molecular pathology B-CL

    WiseEye: next generation expandable and programmable camera trap platform for wildlife research

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    Funding: The work was supported by the RCUK Digital Economy programme to the dot.rural Digital Economy Hub; award reference: EP/G066051/1. The work of S. Newey and RJI was part funded by the Scottish Government's Rural and Environment Science and Analytical Services (RESAS). Details published as an Open Source Toolkit, PLOS Journals at: http://dx.doi.org/10.1371/journal.pone.0169758Peer reviewedPublisher PD

    Swiss Adult Congenital HEart disease Registry (SACHER) - rationale, design and first results.

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    In 2013, a prospective registry for adults with congenital heart disease (CHD) was established in Switzerland, providing detailed data on disease characteristics and outcomes: Swiss Adult Congenital HEart disease Registry (SACHER). Its aim is to improve the knowledge base of outcomes in adults with CHD. The registry design and baseline patient characteristics are reported. All patients with structural congenital heart defects or hereditary aortopathies, followed-up at dedicated adult CHD clinics, are asked to participate in SACHER. Data of participants are pseudonymised and collected in an electronic, web-based, database (secuTrial®). Collected data include detailed diagnosis, type of repair procedures, previous complications and adverse outcomes during follow-up. From May 2014 to December 2016, 2836 patients (54% male, mean age 34 ± 14 years), with a wide variety of congenital heart lesions, have been enrolled into SACHER. Most prevalent were valve lesions (25%), followed by shunt lesions (22%), cyanotic and other complex congenital heart disease (16%), diseases affecting the right heart, i.e., tetralogy of Fallot or Ebstein anomaly (15%), and diseases of the left ventricular outflow tract (13%); 337 patients (12%) had concomitant congenital syndromes. The majority had undergone previous repair procedures (71%), 47% of those had one or more reinterventions. SACHER collects multicentre data on adults with CHD. Its structure enables prospective data analysis to assess detailed, lesion-specific outcomes with the aim to finally improve long-term outcomes

    FACT -- The G-APD revolution in Cherenkov astronomy

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    Since two years, the FACT telescope is operating on the Canary Island of La Palma. Apart from its purpose to serve as a monitoring facility for the brightest TeV blazars, it was built as a major step to establish solid state photon counters as detectors in Cherenkov astronomy. The camera of the First G-APD Cherenkov Telesope comprises 1440 Geiger-mode avalanche photo diodes (G-APD), equipped with solid light guides to increase the effective light collection area of each sensor. Since no sense-line is available, a special challenge is to keep the applied voltage stable although the current drawn by the G-APD depends on the flux of night-sky background photons significantly varying with ambient light conditions. Methods have been developed to keep the temperature and voltage dependent response of the G-APDs stable during operation. As a cross-check, dark count spectra with high statistics have been taken under different environmental conditions. In this presentation, the project, the developed methods and the experience from two years of operation of the first G-APD based camera in Cherenkov astronomy under changing environmental conditions will be presented.Comment: Proceedings of the Nuclear Science Symposium and Medical Imaging Conference (IEEE-NSS/MIC), 201

    FACT - The First G-APD Cherenkov Telescope: Status and Results

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    The First G-APD Cherenkov telescope (FACT) is the first telescope using silicon photon detectors (G-APD aka. SiPM). It is built on the mount of the HEGRA CT3 telescope, still located at the Observatorio del Roque de los Muchachos, and it is successfully in operation since Oct. 2011. The use of Silicon devices promises a higher photon detection efficiency, more robustness and higher precision than photo-multiplier tubes. The FACT collaboration is investigating with which precision these devices can be operated on the long-term. Currently, the telescope is successfully operated from remote and robotic operation is under development. During the past months of operation, the foreseen monitoring program of the brightest known TeV blazars has been carried out, and first physics results have been obtained including a strong flare of Mrk501. An instantaneous flare alert system is already in a testing phase. This presentation will give an overview of the project and summarize its goals, status and first results

    The Affective Impact of Financial Skewness on Neural Activity and Choice

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    Few finance theories consider the influence of “skewness” (or large and asymmetric but unlikely outcomes) on financial choice. We investigated the impact of skewed gambles on subjects' neural activity, self-reported affective responses, and subsequent preferences using functional magnetic resonance imaging (FMRI). Neurally, skewed gambles elicited more anterior insula activation than symmetric gambles equated for expected value and variance, and positively skewed gambles also specifically elicited more nucleus accumbens (NAcc) activation than negatively skewed gambles. Affectively, positively skewed gambles elicited more positive arousal and negatively skewed gambles elicited more negative arousal than symmetric gambles equated for expected value and variance. Subjects also preferred positively skewed gambles more, but negatively skewed gambles less than symmetric gambles of equal expected value. Individual differences in both NAcc activity and positive arousal predicted preferences for positively skewed gambles. These findings support an anticipatory affect account in which statistical properties of gambles—including skewness—can influence neural activity, affective responses, and ultimately, choice
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