263 research outputs found

    Background Light in Potential Sites for the ANTARES Undersea Neutrino Telescope

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    The ANTARES collaboration has performed a series of {\em in situ} measurements to study the background light for a planned undersea neutrino telescope. Such background can be caused by 40^{40}K decays or by biological activity. We report on measurements at two sites in the Mediterranean Sea at depths of 2400~m and 2700~m, respectively. Three photomultiplier tubes were used to measure single counting rates and coincidence rates for pairs of tubes at various distances. The background rate is seen to consist of three components: a constant rate due to 40^{40}K decays, a continuum rate that varies on a time scale of several hours simultaneously over distances up to at least 40~m, and random bursts a few seconds long that are only correlated in time over distances of the order of a meter. A trigger requiring coincidences between nearby photomultiplier tubes should reduce the trigger rate for a neutrino telescope to a manageable level with only a small loss in efficiency.Comment: 18 pages, 8 figures, accepted for publication in Astroparticle Physic

    DNA Barcoding Bromeliaceae: Achievements and Pitfalls

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    <div><h3>Background</h3><p>DNA barcoding has been successfully established in animals as a tool for organismal identification and taxonomic clarification. Slower nucleotide substitution rates in plant genomes have made the selection of a DNA barcode for land plants a much more difficult task. The Plant Working Group of the Consortium for the Barcode of Life (CBOL) recommended the two-marker combination <em>rbcL</em>/<em>matK</em> as a pragmatic solution to a complex trade-off between universality, sequence quality, discrimination, and cost.</p> <h3>Methodology/Principal Findings</h3><p>It is expected that a system based on any one, or a small number of plastid genes will fail within certain taxonomic groups with low amounts of plastid variation, while performing well in others. We tested the effectiveness of the proposed CBOL Plant Working Group barcoding <em>markers</em> for land plants in identifying 46 bromeliad species, a group rich in endemic species from the endangered Brazilian Atlantic Rainforest. Although we obtained high quality sequences with the suggested primers, species discrimination in our data set was only 43.48%. Addition of a third marker, <em>trnH–psbA</em>, did not show significant improvement. This species identification failure in Bromeliaceaecould also be seen in the analysis of the GenBank's <em>matK</em> data set. Bromeliaceae's sequence divergence was almost three times lower than the observed for Asteraceae and Orchidaceae. This low variation rate also resulted in poorly resolved tree topologies. Among the three Bromeliaceae subfamilies sampled, Tillandsioideae was the only one recovered as a monophyletic group with high bootstrap value (98.6%). Species paraphyly was a common feature in our sampling.</p> <h3>Conclusions/Significance</h3><p>Our results show that although DNA barcoding is an important tool for biodiversity assessment, it tends to fail in taxonomy complicated and recently diverged plant groups, such as Bromeliaceae. Additional research might be needed to develop markers capable to discriminate species in these complex botanical groups.</p> </div

    Persistence on prostaglandin ocular hypotensive therapy: an assessment using medication possession and days covered on therapy

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    BACKGROUND:Prior research has demonstrated that medication persistence (continued acquisition of therapy over time) is far from optimal among patients with glaucoma. The purpose of the present study was to evaluate persistence with prostaglandin analogs among glaucoma patients in the first therapy year using a modification of a previously published technique.METHODS:This retrospective analysis of medical and pharmacy claims database included treatment-naive patients dispensed bimatoprost, latanoprost, or travoprost between 1/1/04-12/31/04. "Index agent" was defined as the first agent filled; "index date" was defined as the fill date. Follow-up continued for 358 days. Persistence measures for first therapy year were: (1) whether last fill had sufficient days supply to achieve medication possession at year's end, and (2) number of days for which the index agent was available (days covered). Associations between index agent and medication possession (logistic regression) and days covered (linear regression) were evaluated. Models were adjusted for gender, age, and previous ocular hypertension diagnosis.RESULTS:7873 patients met inclusion criteria (bimatoprost, n = 1464; latanoprost, n = 4994; travoprost, n = 1415). Medication possession was 28% and days covered was 131 when using the unadjusted (pharmacy-reported) days supply estimates and rose to 47-48% and days covered to 228-236 days when days supply was imputed. Compared to latanoprost, odds of achieving medication possession at first year's end were 26-34% lower for bimatoprost and 34-36% lower for travoprost (p [less than or equal to] 0.001 for all comparisons). Days covered in the first year were 21-29 days lower for bimatoprost and 33-42 days lower for travoprost (p [less than or equal to] 0.001 for all comparisons). Failure to refill the index agent within the initial 90 days was a strong predictor of poor persistence. CONCLUSIONS:Persistence with ocular prostaglandin therapy remains a problem. Latanoprost users had greater odds of achieving medication possession and had more days covered during the first therapy year.The results of this study were presented in part at the Annual Meeting of the Association for Research in Vision and Ophthalmology, April 27 to May 1, 2008, in Fort Lauderdale, Florida, USA and at the International Society for Pharmacoeconomics and Outcomes Research 13th Annual International Meeting, May 3 to May 7, 2008, in Toronto, Canada. The research was supported by Pfizer Inc, New York, New York, USA. Assistance in styling the paper for journal submission was provided by Jane G. Murphy, PhD, of Zola Associates and was funded by Pfizer Inc, New York, New York, USA. Sonali Shah, BS Pharm, RPh, MPH provided the impetus and helpful support and advice for design of this study

    Diversity and linkage disequilibrium analysis within a selected set of cultivated tomatoes

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    Within the Dutch genomics initiative the “Centre for Biosystems Genomics” (CBSG) a major research effort is directed at the identification and unraveling of processes and mechanisms affecting fruit quality in tomato. The basis of this fruit quality program was a diverse set of 94 cultivated tomato cultivars, representing a wide spectrum of phenotypes for quality related traits. This paper describes a diversity study performed on these cultivars, using information of 882 AFLP markers, of which 304 markers had a known map position. The AFLP markers were scored as much as possible in a co-dominant fashion. We investigated genome distribution and coverage for the mapped markers and conclude that it proved difficult to arrive at a dense and uniformly distributed coverage of the genome with markers. Mapped markers and unmapped markers were used to investigate population structure. A clear substructure was observed which seemed to coincide with a grouping based on fruit size. Finally, we studied amount and decay of linkage disequilibrium (LD) along the chromosomes. LD was observed over considerable (genetic) distances. We discuss the feasibility of marker-trait association studies and conclude that the amount of genetic variation in our set of cultivars is limited, but that there exists scope for association studies

    Versatile Aggressive Mimicry of Cicadas by an Australian Predatory Katydid

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    Background: In aggressive mimicry, a predator or parasite imitates a signal of another species in order to exploit the recipient of the signal. Some of the most remarkable examples of aggressive mimicry involve exploitation of a complex signal-response system by an unrelated predator species. Methodology/Principal Findings: We have found that predatory Chlorobalius leucoviridis katydids (Orthoptera: Tettigoniidae) can attract male cicadas (Hemiptera: Cicadidae) by imitating the species-specific wing-flick replies of sexually receptive female cicadas. This aggressive mimicry is accomplished both acoustically, with tegminal clicks, and visually, with synchronized body jerks. Remarkably, the katydids respond effectively to a variety of complex, species-specific Cicadettini songs, including songs of many cicada species that the predator has never encountered. Conclusions/Significance: We propose that the versatility of aggressive mimicry in C. leucoviridis is accomplished by exploiting general design elements common to the songs of many acoustically signaling insects that use duets in pairformation. Consideration of the mechanism of versatile mimicry in C. leucoviridis may illuminate processes driving the evolution of insect acoustic signals, which play a central role in reproductive isolation of populations and the formation of species

    Characterisation of the Trichinella spiralis deubiquitinating enzyme, TsUCH37, an evolutionarily conserved proteasome interaction partner.

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    Trichinella spiralis is a parasitic nematode that infects mammals indiscriminately. Although the biggest impact of trichinellosis is observed in developing countries, the parasite is found on all continents except Antarctica. In humans, Trichinella infection contributes globally to helminth related morbidity and disability adjusted life years. In animals, infection is implicated as a serious agricultural problem and drug treatment is largely ineffective. During chronic infection, larvae invade skeletal muscle cells, forming a nurse cell complex in which they become encysted. The nurse cell is a product of the severe disruption of the host cell homeostasis. Proteins of the Ub/proteasome pathway are highly conserved throughout evolution, and considering their importance in the regulation of cell homeostasis, provide interesting and novel therapeutic targets for various diseases. In order to target this system in parasites, pathogen proteins that play a role in this pathway must be identified. We report the identification of the first T. spiralis deubiquitinating enzyme, and show evidence that the function of this protein as a proteasome interaction partner has been evolutionarily conserved. We show that members of this enzyme family are important for T. spiralis survival and that the use of inhibitor compounds may help elucidate their role in infection

    Early detection of cryptic memory and glucose uptake deficits in pre-pathological APP mice

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    Earlier diagnosis and treatment of Alzheimer's disease would greatly benefit from the identification of biomarkers at the prodromal stage. Using a prominent animal model of aspects of the disease, we here show using clinically relevant methodologies that very young, pre-pathological PDAPP mice, which overexpress mutant human amyloid precursor protein in the brain, exhibit two cryptic deficits that are normally undetected using standard methods of assessment. Despite learning a spatial memory task normally and displaying normal brain glucose uptake, they display faster forgetting after a long delay following performance to a criterion, together with a strong impairment of brain glucose uptake at the time of attempted memory retrieval. Preliminary observations suggest that these deficits, likely caused by an impairment in systems consolidation, could be rescued by immunotherapy with an anti-β-amyloid antibody. Our data suggest a biomarker strategy for the early detection of β-amyloid-related abnormalities

    Biology and conservation of freshwater bivalves : past, present and future perspectives

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    Freshwater bivalves have been highly threatened by human activities, and recently their global decline has been causing conservational and social concern. In this paper, we review the most important research events in freshwater bivalve biology calling attention to the main scientific achievements. A great bias exists in the research effort, with much more information available for bivalve species belonging to the Unionida in comparison to other groups. The same is true for the origin of these studies, since the publishing pattern does not always correspond to the hotspots of biodiversity but is concentrated in the northern hemisphere mainly in North America, Europe and Russia, with regions such as Africa and Southeast Asia being quite understudied. We also summarize information about past, present and future perspectives concerning the most important research topics that include taxonomy, systematics, anatomy, physiology, ecology and conservation of freshwater bivalves. Finally, we introduce the articles published in this Hydrobiologia special issue related with the International Meeting on Biology and Conservation of Freshwater Bivalves held in 2012 in Braganc¸a, Portugal.We would like to express our gratitude to our sponsors and institutions, especially to the Polytechnic Institute of Braganca for all the logistic support. We acknowledge all keynote speakers, authors, session chairpersons and especially to all attendees whose contributions were fundamental for the success of this meeting. We would also like to thank all referees of this special issue and to Koen Martens, Editor-in-Chief of Hydrobiologia, for all the valuable comments and suggestions. The chronogram was built with the help of the expert opinion of fellow colleagues Rafael Araujo, Arthur Bogan, Kevin Cummings, Dan Graf, Wendell Haag, Karl-Otto Nagel and David Strayer to whom we are very grateful. The authors acknowledge the support provided by Portuguese Foundation for Science and Technology (FCT) and COMPETE funds-projects CONBI (Contract: PTDC/AAC-AMB/117688/2010) and ECO-IAS (Contract: PTDC/AAC-AMB/116685/2010), and by the European Regional Development Fund (ERDF) through the COMPETE, under the project "PEst-C/MAR/LA0015/2011"
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