Most-cited articles · 2016

The 50 most-cited articles in PeerJ, 2016

Ranked by OpenAlex citation count on 29 October 2026, out of 1,299 eligible articles PeerJ published in 2016. Ranks are frozen; this page will not change. Number one, with 10,764 citations: VSEARCH: a versatile open source tool for metagenomics.

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  1. 1
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    VSEARCH: a versatile open source tool for metagenomics

    Torbjørn Rognes, Tomáš Flouri, Ben Nichols, Christopher Quince, Frédéric Mahé

    10,764 citationsOpen access (CC-BY)doi:10.7717/peerj.2584OpenAlex

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    BACKGROUND: VSEARCH is an open source and free of charge multithreaded 64-bit tool for processing and preparing metagenomics, genomics and population genomics nucleotide sequence data. It is designed as an alternative to the widely used USEARCH tool (Edgar, 2010) for which the source code is not publicly available, algorithm details are only rudimentarily described, and only a memory-confined 32-bit version is freely available for academic use. METHODS: When searching nucleotide sequences, VSEARCH uses a fast heuristic based on words shared by the query and target sequences in order to quickly identify similar sequences, a similar strategy is probably used in USEARCH. VSEARCH then performs optimal global sequence alignment of the query against potential target sequences, using full dynamic programming instead of the seed-and-extend heuristic used by USEARCH. Pairwise alignments are computed in parallel using vectorisation and multiple threads. RESULTS: ), dereplication (full length or prefix), pairwise alignment, reverse complementation, sorting, and subsampling. VSEARCH also…

  2. 2
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    AMAS: a fast tool for alignment manipulation and computing of summary statistics

    Marek L. Borowiec

    909 citationsOpen access (CC-BY)doi:10.7717/peerj.1660OpenAlex

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    The amount of data used in phylogenetics has grown explosively in the recent years and many phylogenies are inferred with hundreds or even thousands of loci and many taxa. These modern phylogenomic studies often entail separate analyses of each of the loci in addition to multiple analyses of subsets of genes or concatenated sequences. Computationally efficient tools for handling and computing properties of thousands of single-locus or large concatenated alignments are needed. Here I present AMAS (Alignment Manipulation And Summary), a tool that can be used either as a stand-alone command-line utility or as a Python package. AMAS works on amino acid and nucleotide alignments and combines capabilities of sequence manipulation with a function that calculates basic statistics. The manipulation functions include conversions among popular formats, concatenation, extracting sites and splitting according to a pre-defined partitioning scheme, creation of replicate data sets, and removal of taxa. The statistics calculated include the number of taxa, alignment length, total count of matrix…

  3. 3
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    The phylogenetic relationships of basal archosauromorphs, with an emphasis on the systematics of proterosuchian archosauriforms

    Martín D. Ezcurra

    414 citationsOpen access (CC-BY)doi:10.7717/peerj.1778OpenAlex

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    The early evolution of archosauromorphs during the Permo-Triassic constitutes an excellent empirical case study to shed light on evolutionary radiations in deep time and the timing and processes of recovery of terrestrial faunas after a mass extinction. However, macroevolutionary studies of early archosauromorphs are currently limited by poor knowledge of their phylogenetic relationships. In particular, one of the main early archosauromorph groups that need an exhaustive phylogenetic study is "Proterosuchia," which as historically conceived includes members of both Proterosuchidae and Erythrosuchidae. A new data matrix composed of 96 separate taxa (several of them not included in a quantitative phylogenetic analysis before) and 600 osteological characters was assembled and analysed to generate a comprehensive higher-level phylogenetic hypothesis of basal archosauromorphs and shed light on the species-level interrelationships of taxa historically identified as proterosuchian archosauriforms. The results of the analysis using maximum parsimony include a polyphyletic "Prolacertiformes"…

  4. 4
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    Green synthesis of silver nanoparticles in aloe vera plant extract prepared by a hydrothermal method and their synergistic antibacterial activity

    Patcharaporn Tippayawat, Nutthakritta Phromviyo, Parichart Boueroy, Apiwat Chompoosor

    402 citationsOpen access (CC-BY)doi:10.7717/peerj.2589OpenAlex

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    Background There is worldwide interest in silver nanoparticles (AgNPs) synthesized by various chemical reactions for use in applications exploiting their antibacterial activity, even though these processes exhibit a broad range of toxicity in vertebrates and invertebrates alike. To avoid the chemical toxicity, biosynthesis (green synthesis) of metal nanoparticles is proposed as a cost-effective and environmental friendly alternative. Aloe vera leaf extract is a medicinal agent with multiple properties including an antibacterial effect. Moreover the constituents of aloe vera leaves include lignin, hemicellulose, and pectins which can be used in the reduction of silver ions to produce as AgNPs@aloe vera (AgNPs@AV) with antibacterial activity. Methods AgNPs were prepared by an eco-friendly hydrothermal method using an aloe vera plant extract solution as both a reducing and stabilizing agent. AgNPs@AV were characterized using XRD and SEM. Additionally, an agar well diffusion method was used to screen for antimicrobial activity. MIC and MBC were used to correlate the concentration of…

  5. 5
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    Leopard (Panthera pardus) status, distribution, and the research efforts across its range

    Andrew P. Jacobson, Peter J. Gerngross, Joseph Lemeris, Rebecca F. Schoonover, Corey Anco and 9 more

    378 citationsOpen access (CC-BY)doi:10.7717/peerj.1974OpenAlex

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    The leopard's (Panthera pardus) broad geographic range, remarkable adaptability, and secretive nature have contributed to a misconception that this species might not be severely threatened across its range. We find that not only are several subspecies and regional populations critically endangered but also the overall range loss is greater than the average for terrestrial large carnivores. To assess the leopard's status, we compile 6,000 records at 2,500 locations from over 1,300 sources on its historic (post 1750) and current distribution. We map the species across Africa and Asia, delineating areas where the species is confirmed present, is possibly present, is possibly extinct or is almost certainly extinct. The leopard now occupies 25-37% of its historic range, but this obscures important differences between subspecies. Of the nine recognized subspecies, three (P. p. pardus, fusca, and saxicolor) account for 97% of the leopard's extant range while another three (P. p. orientalis, nimr, and japonensis) have each lost as much as 98% of their historic range. Isolation, small patch…

  6. 6
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    Phage on tap–a quick and efficient protocol for the preparation of bacteriophage laboratory stocks

    Natasha Bonilla, María Isabel Rojas, Giuliano Netto Flores Cruz, Shr-Hau Hung, Forest L. Rohwer and 1 more

    358 citationsOpen access (CC-BY)doi:10.7717/peerj.2261OpenAlex

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    A major limitation with traditional phage preparations is the variability in titer, salts, and bacterial contaminants between successive propagations. Here we introduce the Phage On Tap (PoT) protocol for the quick and efficient preparation of homogenous bacteriophage (phage) stocks. This method produces homogenous, laboratory-scale, high titer (up to 10(10-11) PFU·ml(-1)), endotoxin reduced phage banks that can be used to eliminate the variability between phage propagations and improve the molecular characterizations of phage. The method consists of five major parts, including phage propagation, phage clean up by 0.22 μm filtering and chloroform treatment, phage concentration by ultrafiltration, endotoxin removal, and the preparation and storage of phage banks for continuous laboratory use. From a starting liquid lysate of > 100 mL, the PoT protocol generated a clean, homogenous, laboratory phage bank with a phage recovery efficiency of 85% within just two days. In contrast, the traditional method took upwards of five days to produce a high titer, but lower volume phage stock with…

  7. 7
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    Continent-wide survey reveals massive decline in African savannah elephants

    Michael J. Chase, Scott Schlossberg, Curtice R. Griffin, Philippe Bouché, Sintayehu Workeneh Dejene and 9 more

    344 citationsOpen access (CC-BY)doi:10.7717/peerj.2354OpenAlex

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    African elephants (Loxodonta africana) are imperiled by poaching and habitat loss. Despite global attention to the plight of elephants, their population sizes and trends are uncertain or unknown over much of Africa. To conserve this iconic species, conservationists need timely, accurate data on elephant populations. Here, we report the results of the Great Elephant Census (GEC), the first continent-wide, standardized survey of African savannah elephants. We also provide the first quantitative model of elephant population trends across Africa. We estimated a population of 352,271 savannah elephants on study sites in 18 countries, representing approximately 93% of all savannah elephants in those countries. Elephant populations in survey areas with historical data decreased by an estimated 144,000 from 2007 to 2014, and populations are currently shrinking by 8% per year continent-wide, primarily due to poaching. Though 84% of elephants occurred in protected areas, many protected areas had carcass ratios that indicated high levels of elephant mortality. Results of the GEC show the…

  8. 8
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    The relationship between mobile phone location sensor data and depressive symptom severity

    Sohrab Saeb, Emily G. Lattie, Stephen Matthew Schueller, Konrad Paul Kording, David C. Mohr

    314 citationsOpen access (CC-BY)doi:10.7717/peerj.2537OpenAlex

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    BACKGROUND: Smartphones offer the hope that depression can be detected using passively collected data from the phone sensors. The aim of this study was to replicate and extend previous work using geographic location (GPS) sensors to identify depressive symptom severity. METHODS: We used a dataset collected from 48 college students over a 10-week period, which included GPS phone sensor data and the Patient Health Questionnaire 9-item (PHQ-9) to evaluate depressive symptom severity at baseline and end-of-study. GPS features were calculated over the entire study, for weekdays and weekends, and in 2-week blocks. RESULTS: -values < .05). We also found that these relationships were stronger when GPS features were calculated from weekend, compared to weekday, data. Although the correlation between baseline PHQ-9 scores with 2-week GPS features diminished as we moved further from baseline, correlations with the end-of-study scores remained significant regardless of the time point used to calculate the features. DISCUSSION: Our findings were consistent with past research demonstrating that…

  9. 9
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    Spider phylogenomics: untangling the Spider Tree of Life

    Nicole L. Garrison, Juanita Rodríguez, Ingi Agnarsson, Jonathan A. Coddington, Charles E. Griswold and 5 more

    308 citationsOpen access (CC-BY)doi:10.7717/peerj.1719OpenAlex

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    Spiders (Order Araneae) are massively abundant generalist arthropod predators that are found in nearly every ecosystem on the planet and have persisted for over 380 million years. Spiders have long served as evolutionary models for studying complex mating and web spinning behaviors, key innovation and adaptive radiation hypotheses, and have been inspiration for important theories like sexual selection by female choice. Unfortunately, past major attempts to reconstruct spider phylogeny typically employing the "usual suspect" genes have been unable to produce a well-supported phylogenetic framework for the entire order. To further resolve spider evolutionary relationships we have assembled a transcriptome-based data set comprising 70 ingroup spider taxa. Using maximum likelihood and shortcut coalescence-based approaches, we analyze eight data sets, the largest of which contains 3,398 gene regions and 696,652 amino acid sites forming the largest phylogenomic analysis of spider relationships produced to date. Contrary to long held beliefs that the orb web is the crowning achievement of…

  10. 10
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    Characterisation of the human uterine microbiome in non-pregnant women through deep sequencing of the V1-2 region of the 16S rRNA gene

    Hans Verstraelen, Ramiro Vilchez‐Vargas, Fabian Desimpel, Ruy Jáuregui, Nele Vankeirsbilck and 5 more

    308 citationsOpen access (CC-BY)doi:10.7717/peerj.1602OpenAlex

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    Background. It is widely assumed that the uterine cavity in non-pregnant women is physiologically sterile, also as a premise to the long-held view that human infants develop in a sterile uterine environment, though likely reflecting under-appraisal of the extent of the human bacterial metacommunity. In an exploratory study, we aimed to investigate the putative presence of a uterine microbiome in a selected series of non-pregnant women through deep sequencing of the V1-2 hypervariable region of the 16S ribosomal RNA (rRNA) gene. Methods. Nineteen women with various reproductive conditions, including subfertility, scheduled for hysteroscopy and not showing uterine anomalies were recruited. Subjects were highly diverse with regard to demographic and medical history and included nulliparous and parous women. Endometrial tissue and mucus harvesting was performed by use of a transcervical device designed to obtain endometrial biopsy, while avoiding cervicovaginal contamination. Bacteria were targeted by use of a barcoded Illumina MiSeq paired-end sequencing method targeting the 16S rRNA…

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    Identification of Salmonella for public health surveillance using whole genome sequencing

    Philip Ashton, Satheesh Nair, Tansy M. Peters, Janet A. Bale, David G. Powell and 8 more

    254 citationsOpen access (CC-BY)doi:10.7717/peerj.1752OpenAlex

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    In April 2015, Public Health England implemented whole genome sequencing (WGS) as a routine typing tool for public health surveillance of Salmonella, adopting a multilocus sequence typing (MLST) approach as a replacement for traditional serotyping. The WGS derived sequence type (ST) was compared to the phenotypic serotype for 6,887 isolates of S. enterica subspecies I, and of these, 6,616 (96%) were concordant. Of the 4% (n = 271) of isolates of subspecies I exhibiting a mismatch, 119 were due to a process error in the laboratory, 26 were likely caused by the serotype designation in the MLST database being incorrect and 126 occurred when two different serovars belonged to the same ST. The population structure of S. enterica subspecies II-IV differs markedly from that of subspecies I and, based on current data, defining the serovar from the clonal complex may be less appropriate for the classification of this group. Novel sequence types that were not present in the MLST database were identified in 8.6% of the total number of samples tested (including S. enterica subspecies I-IV and…

  12. 12
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    Sequencing 16S rRNA gene fragments using the PacBio SMRT DNA sequencing system

    Patrick D. Schloss, Matthew L. Jenior, Charles C. Koumpouras, Sarah L. Westcott, Sarah K. Highlander

    226 citationsOpen access (CC-BY)doi:10.7717/peerj.1869OpenAlex

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    Over the past 10 years, microbial ecologists have largely abandoned sequencing 16S rRNA genes by the Sanger sequencing method and have instead adopted highly parallelized sequencing platforms. These new platforms, such as 454 and Illumina's MiSeq, have allowed researchers to obtain millions of high quality but short sequences. The result of the added sequencing depth has been significant improvements in experimental design. The tradeoff has been the decline in the number of full-length reference sequences that are deposited into databases. To overcome this problem, we tested the ability of the PacBio Single Molecule, Real-Time (SMRT) DNA sequencing platform to generate sequence reads from the 16S rRNA gene. We generated sequencing data from the V4, V3-V5, V1-V3, V1-V5, V1-V6, and V1-V9 variable regions from within the 16S rRNA gene using DNA from a synthetic mock community and natural samples collected from human feces, mouse feces, and soil. The mock community allowed us to assess the actual sequencing error rate and how that error rate changed when different curation methods were…

  13. 13
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    Towards quantitative viromics for both double-stranded and single-stranded DNA viruses

    Simon Roux, Natalie Solonenko, Vinh T. Dang, Bonnie T. Poulos, Sarah M. Schwenck and 4 more

    214 citationsOpen access (CC-BY)doi:10.7717/peerj.2777OpenAlex

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    Background Viruses strongly influence microbial population dynamics and ecosystem functions. However, our ability to quantitatively evaluate those viral impacts is limited to the few cultivated viruses and double-stranded DNA (dsDNA) viral genomes captured in quantitative viral metagenomes (viromes). This leaves the ecology of non-dsDNA viruses nearly unknown, including single-stranded DNA (ssDNA) viruses that have been frequently observed in viromes, but not quantified due to amplification biases in sequencing library preparations (Multiple Displacement Amplification, Linker Amplification or Tagmentation). Methods Here we designed mock viral communities including both ssDNA and dsDNA viruses to evaluate the capability of a sequencing library preparation approach including an Adaptase step prior to Linker Amplification for quantitative amplification of both dsDNA and ssDNA templates. We then surveyed aquatic samples to provide first estimates of the abundance of ssDNA viruses. Results Mock community experiments confirmed the biased nature of existing library preparation methods for…

  14. 14
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    Consumer grade EEG devices: are they usable for control tasks?

    Rytis Maskeliūnas, Robertas Damaševičius, Ignas Martišius, Mindaugas Vasiljevas

    211 citationsOpen access (CC-BY)doi:10.7717/peerj.1746OpenAlex

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    We present the evaluation of two well-known, low-cost consumer-grade EEG devices: the Emotiv EPOC and the Neurosky MindWave. Problems with using the consumer-grade EEG devices (BCI illiteracy, poor technical characteristics, and adverse EEG artefacts) are discussed. The experimental evaluation of the devices, performed with 10 subjects asked to perform concentration/relaxation and blinking recognition tasks, is given. The results of statistical analysis show that both devices exhibit high variability and non-normality of attention and meditation data, which makes each of them difficult to use as an input to control tasks. BCI illiteracy may be a significant problem, as well as setting up of the proper environment of the experiment. The results of blinking recognition show that using the Neurosky device means recognition accuracy is less than 50%, while the Emotiv device has achieved a recognition accuracy of more than 75%; for tasks that require concentration and relaxation of subjects, the Emotiv EPOC device has performed better (as measured by the recognition accuracy) by ∼9%.…

  15. 15
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    Ecological solutions to reef degradation: optimizing coral reef restoration in the Caribbean and Western Atlantic

    Diego Lirman, Stephanie A. Schopmeyer

    210 citationsOpen access (CC-BY)doi:10.7717/peerj.2597OpenAlex

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    Reef restoration activities have proliferated in response to the need to mitigate coral declines and recover lost reef structure, function, and ecosystem services. Here, we describe the recent shift from costly and complex engineering solutions to recover degraded reef structure to more economical and efficient ecological approaches that focus on recovering the living components of reef communities. We review the adoption and expansion of the coral gardening framework in the Caribbean and Western Atlantic where practitioners now grow and outplant 10,000's of corals onto degraded reefs each year. We detail the steps for establishing a gardening program as well as long-term goals and direct and indirect benefits of this approach in our region. With a strong scientific basis, coral gardening activities now contribute significantly to reef and species recovery, provide important scientific, education, and outreach opportunities, and offer alternate livelihoods to local stakeholders. While challenges still remain, the transition from engineering to ecological solutions for reef…

  16. 16
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    A horizon scan of future threats and opportunities for pollinators and pollination

    Mark J. F. Brown, Lynn V. Dicks, Robert J. Paxton, Katherine C. R. Baldock, Andrew B. Barron and 12 more

    198 citationsOpen access (CC-BY)doi:10.7717/peerj.2249OpenAlex

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    Background. Pollinators, which provide the agriculturally and ecologically essential service of pollination, are under threat at a global scale. Habitat loss and homogenisation, pesticides, parasites and pathogens, invasive species, and climate change have been identified as past and current threats to pollinators. Actions to mitigate these threats, e.g., agri-environment schemes and pesticide-use moratoriums, exist, but have largely been applied post-hoc. However, future sustainability of pollinators and the service they provide requires anticipation of potential threats and opportunities before they occur, enabling timely implementation of policy and practice to prevent, rather than mitigate, further pollinator declines. Methods.Using a horizon scanning approach we identified issues that are likely to impact pollinators, either positively or negatively, over the coming three decades. Results.Our analysis highlights six high priority, and nine secondary issues. High priorities are: (1) corporate control of global agriculture, (2) novel systemic pesticides, (3) novel RNA viruses,…

  17. 17
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    Job satisfaction and intention to quit: an empirical analysis of nurses in Turkey

    Abdul Kadar Muhammad Masum, Md. Abul Kalam Azad, Kazi Enamul Hoque, Loo‐See Beh, Peter Wänke and 1 more

    195 citationsOpen access (CC-BY)doi:10.7717/peerj.1896OpenAlex

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    The aim of this study was to identify the facets influencing job satisfaction and intention to quit of nurses employed in Turkey. Using a non-probability sampling technique, 417 nurses from six large private hospitals were surveyed from March 2014 to June 2014. The nurses' demographic data, their job-related satisfaction and turnover intentions were recorded through a self-administered questionnaire. In this study, descriptive and bivariate analyses were used to explore data, and multivariate analysis was performed using logistic regression. Nurses' job satisfaction was found at a moderate level with 61% of the nurses intended to quit. Nevertheless, nurses reported a high satisfaction level with work environment, supervisor support, and co-workers among the selected nine facets of job satisfaction. They also reported a low satisfaction level with contingent reward, fringe benefits, and pay. The impact of demographic characteristics on job satisfaction and intention to quit was also examined. The study revealed a negative relationship between job satisfaction and intention to quit…

  18. 18
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    Region-of-interest analyses of one-dimensional biomechanical trajectories: bridging 0D and 1D theory, augmenting statistical power

    Todd C. Pataky, Mark A. Robinson, Jos Vanrenterghem

    193 citationsOpen access (CC-BY)doi:10.7717/peerj.2652OpenAlex

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    One-dimensional (1D) kinematic, force, and EMG trajectories are often analyzed using zero-dimensional (0D) metrics like local extrema. Recently whole-trajectory 1D methods have emerged in the literature as alternatives. Since 0D and 1D methods can yield qualitatively different results, the two approaches may appear to be theoretically distinct. The purposes of this paper were (a) to clarify that 0D and 1D approaches are actually just special cases of a more general region-of-interest (ROI) analysis framework, and (b) to demonstrate how ROIs can augment statistical power. We first simulated millions of smooth, random 1D datasets to validate theoretical predictions of the 0D, 1D and ROI approaches and to emphasize how ROIs provide a continuous bridge between 0D and 1D results. We then analyzed a variety of public datasets to demonstrate potential effects of ROIs on biomechanical conclusions. Results showed, first, that a priori ROI particulars can qualitatively affect the biomechanical conclusions that emerge from analyses and, second, that ROIs derived from exploratory/pilot analyses…

  19. 19
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    Evaluation of unmanned aerial vehicle shape, flight path and camera type for waterfowl surveys: disturbance effects and species recognition

    John F. McEvoy, Graham P. Hall, Paul G. McDonald

    185 citationsOpen access (CC-BY)doi:10.7717/peerj.1831OpenAlex

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    The use of unmanned aerial vehicles (UAVs) for ecological research has grown rapidly in recent years, but few studies have assessed the disturbance impacts of these tools on focal subjects, particularly when observing easily disturbed species such as waterfowl. In this study we assessed the level of disturbance that a range of UAV shapes and sizes had on free-living, non-breeding waterfowl surveyed in two sites in eastern Australia between March and May 2015, as well as the capability of airborne digital imaging systems to provide adequate resolution for unambiguous species identification of these taxa. We found little or no obvious disturbance effects on wild, mixed-species flocks of waterfowl when UAVs were flown at least 60m above the water level (fixed wing models) or 40m above individuals (multirotor models). Disturbance in the form of swimming away from the UAV through to leaving the water surface and flying away from the UAV was visible at lower altitudes and when fixed-wing UAVs either approached subjects directly or rapidly changed altitude and/or direction near animals.…

  20. 20
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    Estimating and comparing microbial diversity in the presence of sequencing errors

    Chun‐Huo Chiu, Anne Chao

    178 citationsOpen access (CC-BY)doi:10.7717/peerj.1634OpenAlex

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    Estimating and comparing microbial diversity are statistically challenging due to limited sampling and possible sequencing errors for low-frequency counts, producing spurious singletons. The inflated singleton count seriously affects statistical analysis and inferences about microbial diversity. Previous statistical approaches to tackle the sequencing errors generally require different parametric assumptions about the sampling model or about the functional form of frequency counts. Different parametric assumptions may lead to drastically different diversity estimates. We focus on nonparametric methods which are universally valid for all parametric assumptions and can be used to compare diversity across communities. We develop here a nonparametric estimator of the true singleton count to replace the spurious singleton count in all methods/approaches. Our estimator of the true singleton count is in terms of the frequency counts of doubletons, tripletons and quadrupletons, provided these three frequency counts are reliable. To quantify microbial alpha diversity for an individual…

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    Ship noise extends to frequencies used for echolocation by endangered killer whales

    Scott R. Veirs, Val R. Veirs, JASON D. WOOD

    173 citationsOpen access (CC-BY)doi:10.7717/peerj.1657OpenAlex

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    Combining calibrated hydrophone measurements with vessel location data from the Automatic Identification System, we estimate underwater sound pressure levels for 1,582 unique ships that transited the core critical habitat of the endangered Southern Resident killer whales during 28 months between March, 2011, and October, 2013. Median received spectrum levels of noise from 2,809 isolated transits are elevated relative to median background levels not only at low frequencies (20-30 dB re 1 µPa(2)/Hz from 100 to 1,000 Hz), but also at high frequencies (5-13 dB from 10,000 to 96,000 Hz). Thus, noise received from ships at ranges less than 3 km extends to frequencies used by odontocetes. Broadband received levels (11.5-40,000 Hz) near the shoreline in Haro Strait (WA, USA) for the entire ship population were 110 ± 7 dB re 1 µPa on average. Assuming near-spherical spreading based on a transmission loss experiment we compute mean broadband source levels for the ship population of 173 ± 7 dB re 1 µPa 1 m without accounting for frequency-dependent absorption. Mean ship speed was 7.3 ± 2.0 m/s…

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    Whole genome sequencing of Streptococcus pneumoniae : development, evaluation and verification of targets for serogroup and serotype prediction using an automated pipeline

    Georgia Kapatai, Carmen L. Sheppard, Ali Al‐Shahib, David J. Litt, Anthony P. Underwood and 2 more

    170 citationsOpen access (CC-BY)doi:10.7717/peerj.2477OpenAlex

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    Streptococcus pneumoniae typically express one of 92 serologically distinct capsule polysaccharide (cps) types (serotypes). Some of these serotypes are closely related to each other; using the commercially available typing antisera, these are assigned to common serogroups containing types that show cross-reactivity. In this serotyping scheme, factor antisera are used to allocate serotypes within a serogroup, based on patterns of reactions. This serotyping method is technically demanding, requires considerable experience and the reading of the results can be subjective. This study describes the analysis of the S. pneumoniae capsular operon genetic sequence to determine serotype distinguishing features and the development, evaluation and verification of an automated whole genome sequence (WGS)-based serotyping bioinformatics tool, PneumoCaT (Pneumococcal Capsule Typing). Initially, WGS data from 871 S. pneumoniae isolates were mapped to reference cps locus sequences for the 92 serotypes. Thirty-two of 92 serotypes could be unambiguously identified based on sequence similarities within…

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    Isolation of an antimicrobial compound produced by bacteria associated with reef-building corals

    Jean‐Baptiste Raina, Dianne M. Tapiolas, Cherie Ann Motti, Sylvain Forêt, Torsten Seemann and 3 more

    170 citationsOpen access (CC-BY)doi:10.7717/peerj.2275OpenAlex

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    Bacterial communities associated with healthy corals produce antimicrobial compounds that inhibit the colonization and growth of invasive microbes and potential pathogens. To date, however, bacteria-derived antimicrobial molecules have not been identified in reef-building corals. Here, we report the isolation of an antimicrobial compound produced by Pseudovibrio sp. P12, a common and abundant coral-associated bacterium. This strain was capable of metabolizing dimethylsulfoniopropionate (DMSP), a sulfur molecule produced in high concentrations by reef-building corals and playing a role in structuring their bacterial communities. Bioassay-guided fractionation coupled with nuclear magnetic resonance (NMR) and mass spectrometry (MS), identified the antimicrobial as tropodithietic acid (TDA), a sulfur-containing compound likely derived from DMSP catabolism. TDA was produced in large quantities by Pseudovibrio sp., and prevented the growth of two previously identified coral pathogens, Vibrio coralliilyticus and V. owensii, at very low concentrations (0.5 μg/mL) in agar diffusion assays.…

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    Enzymatically crosslinked gelatin hydrogel promotes the proliferation of adipose tissue-derived stromal cells

    Gang Yang, Zhenghua Xiao, Xiaomei Ren, Haiyan Long, Hong Qian and 2 more

    165 citationsOpen access (CC-BY)doi:10.7717/peerj.2497OpenAlex

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    Gelatin hydrogel crosslinked by microbial transglutaminase (mTG) exhibits excellent performance in cell adhesion, proliferation, and differentiation. We examined the gelation time and gel strength of gelatin/mTG hydrogels in various proportions to investigate their physical properties and tested their degradation performances in vitro . Cell morphology and viability of adipose tissue-derived stromal cells (ADSCs) cultured on the 2D gel surface or in 3D hydrogel encapsulation were evaluated by immunofluorescence staining. Cell proliferation was tested via Alamar Blue assay. To investigate the hydrogel effect on cell differentiation, the cardiac-specific gene expression levelsof Nkx2.5, Myh6, Gja1, and Mef2c in encapsulated ADSCs with or without cardiac induction medium were detected by real-time RT-PCR. Cell release from the encapsulated status and cell migration in a 3D hydrogel model were assessed in vitro . Results show that the gelatin/mTG hydrogels are not cytotoxic and that their mechanical properties are adjustable. Hydrogel degradation is related to gel concentration and the…

  25. 25
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    Testing the potential of a ribosomal 16S marker for DNA metabarcoding of insects

    Vasco Elbrecht, Pierre Taberlet, Tony Déjean, Alice Valentini, Philippe Usseglio‐Polatera and 4 more

    164 citationsOpen access (CC-BY)doi:10.7717/peerj.1966OpenAlex

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    Cytochrome c oxidase I (COI) is a powerful marker for DNA barcoding of animals, with good taxonomic resolution and a large reference database. However, when used for DNA metabarcoding, estimation of taxa abundances and species detection are limited due to primer bias caused by highly variable primer binding sites across the COI gene. Therefore, we explored the ability of the 16S ribosomal DNA gene as an alternative metabarcoding marker for species level assessments. Ten bulk samples, each containing equal amounts of tissue from 52 freshwater invertebrate taxa, were sequenced with the Illumina NextSeq 500 system. The 16S primers amplified three more insect species than the Folmer COI primers and amplified more equally, probably due to decreased primer bias. Estimation of biomass might be less biased with 16S than with COI, although variation in read abundances of two orders of magnitudes is still observed. According to these results, the marker choice depends on the scientific question. If the goal is to obtain a taxonomic identification at the species level, then COI is more…

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    Spatio-temporal monitoring of deep-sea communities using metabarcoding of sediment DNA and RNA

    Magdalena Guardiola, Owen Simon Wangensteen, Pierre Taberlet, Éric Coissac, María Jesús Uriz and 1 more

    157 citationsOpen access (CC-BY)doi:10.7717/peerj.2807OpenAlex

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    We assessed spatio-temporal patterns of diversity in deep-sea sediment communities using metabarcoding. We chose a recently developed eukaryotic marker based on the v7 region of the 18S rRNA gene. Our study was performed in a submarine canyon and its adjacent slope in the Northwestern Mediterranean Sea, sampled along a depth gradient at two different seasons. We found a total of 5,569 molecular operational taxonomic units (MOTUs), dominated by Metazoa, Alveolata and Rhizaria. Among metazoans, Nematoda, Arthropoda and Annelida were the most diverse. We found a marked heterogeneity at all scales, with important differences between layers of sediment and significant changes in community composition with zone (canyon vs slope), depth, and season. We compared the information obtained from metabarcoding DNA and RNA and found more total MOTUs and more MOTUs per sample with DNA (ca. 20% and 40% increase, respectively). Both datasets showed overall similar spatial trends, but most groups had higher MOTU richness with the DNA template, while others, such as nematodes, were more diverse in the…

  27. 27
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    The potential effects of climate change on amphibian distribution, range fragmentation and turnover in China

    Renyan Duan, Xiaoquan Kong, Min-Yi Huang, Sara Varela, Xiang Ji

    147 citationsOpen access (CC-BY)doi:10.7717/peerj.2185OpenAlex

    Show abstract

    Many studies predict that climate change will cause species movement and turnover, but few have considered the effect of climate change on range fragmentation for current species and/or populations. We used MaxEnt to predict suitable habitat, fragmentation and turnover for 134 amphibian species in China under 40 future climate change scenarios spanning four pathways (RCP2.6, RCP4.5, RCP6 and RCP8.5) and two time periods (the 2050s and 2070s). Our results show that climate change may cause a major shift in spatial patterns of amphibian diversity. Amphibians in China would lose 20% of their original ranges on average; the distribution outside current ranges would increase by 15%. Suitable habitats for over 90% of species will be located in the north of their current range, for over 95% of species in higher altitudes (from currently 137-4,124 m to 286-4,396 m in the 2050s or 314-4,448 m in the 2070s), and for over 75% of species in the west of their current range. Also, our results predict two different general responses to the climate change: some species contract their ranges while…

  28. 28
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    Hairiness: the missing link between pollinators and pollination

    Jamie R. Stavert, G. Liñán, Jacqueline Rae Beggs, Brad G. Howlett, David E. Pattemore and 1 more

    138 citationsOpen access (CC-BY)doi:10.7717/peerj.2779OpenAlex

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    Background Functional traits are the primary biotic component driving organism influence on ecosystem functions; in consequence, traits are widely used in ecological research. However, most animal trait-based studies use easy-to-measure characteristics of species that are at best only weakly associated with functions. Animal-mediated pollination is a key ecosystem function and is likely to be influenced by pollinator traits, but to date no one has identified functional traits that are simple to measure and have good predictive power. Methods Here, we show that a simple, easy to measure trait (hairiness) can predict pollinator effectiveness with high accuracy. We used a novel image analysis method to calculate entropy values for insect body surfaces as a measure of hairiness. We evaluated the power of our method for predicting pollinator effectiveness by regressing pollinator hairiness (entropy) against single visit pollen deposition (SVD) and pollen loads on insects. We used linear models and AIC C model selection to determine which body regions were the best predictors of SVD and…

  29. 29
    top 2.3%

    A comprehensive investigation of mesophotic coral ecosystems in the Hawaiian Archipelago

    Richard L. Pyle, Raymond C. Boland, Holly Bolick, Brian W. Bowen, Christina J. Bradley and 11 more

    137 citationsOpen access (CC-BY)doi:10.7717/peerj.2475OpenAlex

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    Although the existence of coral-reef habitats at depths to 165 m in tropical regions has been known for decades, the richness, diversity, and ecological importance of mesophotic coral ecosystems (MCEs) has only recently become widely acknowledged. During an interdisciplinary effort spanning more than two decades, we characterized the most expansive MCEs ever recorded, with vast macroalgal communities and areas of 100% coral cover between depths of 50–90 m extending for tens of km 2 in the Hawaiian Archipelago. We used a variety of sensors and techniques to establish geophysical characteristics. Biodiversity patterns were established from visual and video observations and collected specimens obtained from submersible, remotely operated vehicles and mixed-gas SCUBA and rebreather dives. Population dynamics based on age, growth and fecundity estimates of selected fish species were obtained from laser-videogrammetry, specimens, and otolith preparations. Trophic dynamics were determined using carbon and nitrogen stable isotopic analyses on more than 750 reef fishes. MCEs are associated…

  30. 30
    top 2.4%

    Similarities between decapod and insect neuropeptidomes

    Jan A. Veenstra

    137 citationsOpen access (CC-BY)doi:10.7717/peerj.2043OpenAlex

    Show abstract

    Background. Neuropeptides are important regulators of physiological processes and behavior. Although they tend to be generally well conserved, recent results using trancriptome sequencing on decapod crustaceans give the impression of significant differences between species, raising the question whether such differences are real or artefacts. Methods. The BLAST+ program was used to find short reads coding neuropeptides and neurohormons in publicly available short read archives. Such reads were then used to find similar reads in the same archives, and the DNA assembly program Trinity was employed to construct contigs encoding the neuropeptide precursors as completely as possible. Results. The seven decapod species analyzed in this fashion, the crabs Eriocheir sinensis, Carcinus maenas and Scylla paramamosain, the shrimp Litopenaeus vannamei, the lobster Homarus americanus, the fresh water prawn Macrobrachium rosenbergii and the crayfish Procambarus clarkii had remarkably similar neuropeptidomes. Although some neuropeptide precursors could not be assembled, in many cases individual…

  31. 31
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    Article processing charges for open access publication—the situation for research intensive universities in the USA and Canada

    David Solomon, Bo‐Christer Björk

    134 citationsOpen access (CC-BY)doi:10.7717/peerj.2264OpenAlex

    Show abstract

    Background. Open access (OA) publishing via article processing charges (APCs) is growing as an alternative to subscription publishing. The Pay It Forward (PIF) Project is exploring the feasibility of transitioning from paying subscriptions to funding APCs for faculty at research intensive universities. Estimating of the cost of APCs for the journals authors at research intensive universities tend to publish is essential for the PIF project and similar initiatives. This paper presents our research into this question. Methods. We identified APC prices for publications by authors at the 4 research intensive United States (US) and Canadian universities involved in the study. We also obtained APC payment records from several Western European universities and funding agencies. Both data sets were merged with Web of Science (WoS) metadata. We calculated the average APCs for articles and proceedings in 13 discipline categories published by researchers at research intensive universities. We also identified 41 journals published by traditionally subscription publishers which have recently…

  32. 32
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    Prevention of necrotizing enterocolitis with probiotics: a systematic review and meta-analysis

    Sonja C. Sawh, Santosh Deshpande, Sandy Jansen, Christopher J. Reynaert, Philip M. Jones

    133 citationsOpen access (CC-BY)doi:10.7717/peerj.2429OpenAlex

    Show abstract

    CONTEXT: Necrotizing enterocolitis (NEC) is the most frequent gastrointestinal emergency in neonates. The microbiome of the preterm gut may regulate the integrity of the intestinal mucosa. Probiotics may positively contribute to mucosal integrity, potentially reducing the risk of NEC in neonates. OBJECTIVE: To perform an updated systematic review and meta-analysis on the efficacy and safety of probiotics for the prevention of NEC in premature infants. DATA SOURCES: Structured searches were performed in: Medline, Embase, and the Cochrane Central Register of Controlled Trials (all via Ovid, from 2013 to January 2015). Clinical trial registries and electronically available conference materials were also searched. An updated search was conducted June 3, 2016. STUDY SELECTION: Randomized trials including infants less than 37 weeks gestational age or less than 2,500 g on probiotic vs. standard therapy. DATA EXTRACTION: Data extraction of the newly-identified trials with a double check of the previously-identified trials was performed using a standardized data collection tool. RESULTS: =…

  33. 33
    top 2.6%

    MOST: a modified MLST typing tool based on short read sequencing

    Rediat Tewolde, Timothy J. Dallman, Ulf Schaefer, Carmen L. Sheppard, Philip Ashton and 5 more

    130 citationsOpen access (CC-BY)doi:10.7717/peerj.2308OpenAlex

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    Multilocus sequence typing (MLST) is an effective method to describe bacterial populations. Conventionally, MLST involves Polymerase Chain Reaction (PCR) amplification of housekeeping genes followed by Sanger DNA sequencing. Public Health England (PHE) is in the process of replacing the conventional MLST methodology with a method based on short read sequence data derived from Whole Genome Sequencing (WGS). This paper reports the comparison of the reliability of MLST results derived from WGS data, comparing mapping and assembly-based approaches to conventional methods using 323 bacterial genomes of diverse species. The sensitivity of the two WGS based methods were further investigated with 26 mixed and 29 low coverage genomic data sets from Salmonella enteridis and Streptococcus pneumoniae. Of the 323 samples, 92.9% (n = 300), 97.5% (n = 315) and 99.7% (n = 322) full MLST profiles were derived by the conventional method, assembly- and mapping-based approaches, respectively. The concordance between samples that were typed by conventional (92.9%) and both WGS methods was 100%. From the…

  34. 34
    top 2.7%

    Proficient brain for optimal performance: the MAP model perspective

    Maurizio Bertollo, Selenia di Fronso, Edson Filho, Silvia Conforto, Maurizio Schmid and 3 more

    124 citationsOpen access (CC-BY)doi:10.7717/peerj.2082OpenAlex

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    Background. The main goal of the present study was to explore theta and alpha event-related desynchronization/synchronization (ERD/ERS) activity during shooting performance. We adopted the idiosyncratic framework of the multi-action plan (MAP) model to investigate different processing modes underpinning four types of performance. In particular, we were interested in examining the neural activity associated with optimal-automated (Type 1) and optimal-controlled (Type 2) performances. Methods. Ten elite shooters (6 male and 4 female) with extensive international experience participated in the study. ERD/ERS analysis was used to investigate cortical dynamics during performance. A 4 × 3 (performance types × time) repeated measures analysis of variance was performed to test the differences among the four types of performance during the three seconds preceding the shots for theta, low alpha, and high alpha frequency bands. The dependent variables were the ERD/ERS percentages in each frequency band (i.e., theta, low alpha, high alpha) for each electrode site across the scalp. This analysis…

  35. 35
    top 2.7%

    Localization and segmentation of optic disc in retinal images using Circular Hough transform and Grow Cut algorithm

    Muhammad Abdullah, Muhammad Moazam Fraz, Sarah Ann Barman

    121 citationsOpen access (CC-BY)doi:10.7717/peerj.2003OpenAlex

    Show abstract

    Automated retinal image analysis has been emerging as an important diagnostic tool for early detection of eye-related diseases such as glaucoma and diabetic retinopathy. In this paper, we have presented a robust methodology for optic disc detection and boundary segmentation, which can be seen as the preliminary step in the development of a computer-assisted diagnostic system for glaucoma in retinal images. The proposed method is based on morphological operations, the circular Hough transform and the grow-cut algorithm. The morphological operators are used to enhance the optic disc and remove the retinal vasculature and other pathologies. The optic disc center is approximated using the circular Hough transform, and the grow-cut algorithm is employed to precisely segment the optic disc boundary. The method is quantitatively evaluated on five publicly available retinal image databases DRIVE, DIARETDB1, CHASE_DB1, DRIONS-DB, Messidor and one local Shifa Hospital Database. The method achieves an optic disc detection success rate of 100% for these databases with the exception of 99.09%…

  36. 36
    top 2.8%

    Evidence for a trophic cascade on rocky reefs following sea star mass mortality in British Columbia

    Jessica Schultz, Ryan N. Cloutier, Isabelle M. Côté

    117 citationsOpen access (CC-BY)doi:10.7717/peerj.1980OpenAlex

    Show abstract

    Echinoderm population collapses, driven by disease outbreaks and climatic events, may be important drivers of population dynamics, ecological shifts and biodiversity. The northeast Pacific recently experienced a mass mortality of sea stars. In Howe Sound, British Columbia, the sunflower star Pycnopodia helianthoides-a previously abundant predator of bottom-dwelling invertebrates-began to show signs of a wasting syndrome in early September 2013, and dense aggregations disappeared from many sites in a matter of weeks. Here, we assess changes in subtidal community composition by comparing the abundance of fish, invertebrates and macroalgae at 20 sites in Howe Sound before and after the 2013 sea star mortality to evaluate evidence for a trophic cascade. We observed changes in the abundance of several species after the sea star mortality, most notably a four-fold increase in the number of green sea urchins, Strongylocentrotus droebachiensis, and a significant decline in kelp cover, which are together consistent with a trophic cascade. Qualitative data on the abundance of sunflower stars…

  37. 37
    top 2.9%

    Fibroblast growth factors as tissue repair and regeneration therapeutics

    Quentin M Nunes, Yong Li, Changye Sun, Tarja K Kinnunen, David Garth Fernig

    117 citationsOpen access (CC-BY)doi:10.7717/peerj.1535OpenAlex

    Show abstract

    Cell communication is central to the integration of cell function required for the development and homeostasis of multicellular animals. Proteins are an important currency of cell communication, acting locally (auto-, juxta-, or paracrine) or systemically (endocrine). The fibroblast growth factor (FGF) family contributes to the regulation of virtually all aspects of development and organogenesis, and after birth to tissue maintenance, as well as particular aspects of organism physiology. In the West, oncology has been the focus of translation of FGF research, whereas in China and to an extent Japan a major focus has been to use FGFs in repair and regeneration settings. These differences have their roots in research history and aims. The Chinese drive into biotechnology and the delivery of engineered clinical grade FGFs by a major Chinese research group were important enablers in this respect. The Chinese language clinical literature is not widely accessible. To put this into context, we provide the essential molecular and functional background to the FGF communication system…

  38. 38
    top 3%

    The (mis)measurement of the Dark Triad Dirty Dozen: exploitation at the core of the scale

    Petri Kajonius, Björn N. Persson, Patricia Rosenberg, Danilo Garcia

    116 citationsOpen access (CC-BY)doi:10.7717/peerj.1748OpenAlex

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    Background. The dark side of human character has been conceptualized in the Dark Triad Model: Machiavellianism, psychopathy, and narcissism. These three dark traits are often measured using single long instruments for each one of the traits. Nevertheless, there is a necessity of short and valid personality measures in psychological research. As an independent research group, we replicated the factor structure, convergent validity and item response for one of the most recent and widely used short measures to operationalize these malevolent traits, namely, Jonason's Dark Triad Dirty Dozen. We aimed to expand the understanding of what the Dirty Dozen really captures because the mixed results on construct validity in previous research. Method. We used the largest sample to date to respond to the Dirty Dozen (N = 3,698). We firstly investigated the factor structure using Confirmatory Factor Analysis and an exploratory distribution analysis of the items in the Dirty Dozen. Secondly, using a sub-sample (n = 500) and correlation analyses, we investigated the Dirty Dozen dark traits…

  39. 39
    top 3.1%

    An extensive comparison of species-abundance distribution models

    Elita Baldridge, David J. Harris, Xiao Xiao, Ethan P. White

    115 citationsOpen access (CC-BY)doi:10.7717/peerj.2823OpenAlex

    Show abstract

    A number of different models have been proposed as descriptions of the species-abundance distribution (SAD). Most evaluations of these models use only one or two models, focus on only a single ecosystem or taxonomic group, or fail to use appropriate statistical methods. We use likelihood and AIC to compare the fit of four of the most widely used models to data on over 16,000 communities from a diverse array of taxonomic groups and ecosystems. Across all datasets combined the log-series, Poisson lognormal, and negative binomial all yield similar overall fits to the data. Therefore, when correcting for differences in the number of parameters the log-series generally provides the best fit to data. Within individual datasets some other distributions performed nearly as well as the log-series even after correcting for the number of parameters. The Zipf distribution is generally a poor characterization of the SAD.

  40. 40
    top 3.1%

    A review and meta-analysis of the enemy release hypothesis in plant–herbivorous insect systems

    Kim Meijer, Menno Schilthuizen, Leo W. Beukeboom, Christian Smit

    115 citationsOpen access (CC-BY)doi:10.7717/peerj.2778OpenAlex

    Show abstract

    A suggested mechanism for the success of introduced non-native species is the enemy release hypothesis (ERH). Many studies have tested the predictions of the ERH using the community approach (native and non-native species studied in the same habitat) or the biogeographical approach (species studied in their native and non-native range), but results are highly variable, possibly due to large variety of study systems incorporated. We therefore focused on one specific system: plants and their herbivorous insects. We performed a systematic review and compiled a large number (68) of datasets from studies comparing herbivorous insects on native and non-native plants using the community or biogeographical approach. We performed a meta-analysis to test the predictions from the ERH for insect diversity (number of species), insect load (number of individuals) and level of herbivory for both the community and biogeographical approach. For both the community and biogeographical approach insect diversity was significantly higher on native than on non-native plants. Insect load tended to be…

  41. 41
    top 3.2%

    Proteogenomic analyses indicate bacterial methylotrophy and archaeal heterotrophy are prevalent below the grass root zone

    Cristina N. Butterfield, Zhou Li, Peter F Andeer, Susan E. Spaulding, Brian C. Thomas and 8 more

    114 citationsOpen access (CC-BY)doi:10.7717/peerj.2687OpenAlex

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    . However, understanding of the microbiology of this process is limited because most culture-independent methods cannot link metabolic processes to the organisms present, and this link to causative agents is necessary to predict the results of perturbations on the system. We collected soil samples at two sub-root depths (10-20 cm and 30-40 cm) before and after a rainfall-driven nutrient perturbation event in a Northern California grassland that experiences a Mediterranean climate. From ten samples, we reconstructed 198 metagenome-assembled genomes that represent all major phylotypes. We also quantified 6,835 proteins and 175 metabolites and showed that after the rain event the concentrations of many sugars and amino acids approach zero at the base of the soil profile. Unexpectedly, the genomes of novel members of the Gemmatimonadetes and Candidate Phylum Rokubacteria phyla encode pathways for methylotrophy. We infer that these abundant organisms contribute substantially to carbon turnover in the soil, given that methylotrophy proteins were among the most abundant proteins in the…

  42. 42
    top 3.3%

    PhyloPythiaS+: a self-training method for the rapid reconstruction of low-ranking taxonomic bins from metagenomes

    Ivan Gregor, Johannes Dröge, Melanie Schirmer, Christopher Quince, Alice Carolyn McHardy

    114 citationsOpen access (CC-BY)doi:10.7717/peerj.1603OpenAlex

    Show abstract

    Background. Metagenomics is an approach for characterizing environmental microbial communities in situ, it allows their functional and taxonomic characterization and to recover sequences from uncultured taxa. This is often achieved by a combination of sequence assembly and binning, where sequences are grouped into 'bins' representing taxa of the underlying microbial community. Assignment to low-ranking taxonomic bins is an important challenge for binning methods as is scalability to Gb-sized datasets generated with deep sequencing techniques. One of the best available methods for species bins recovery from deep-branching phyla is the expert-trained PhyloPythiaS package, where a human expert decides on the taxa to incorporate in the model and identifies 'training' sequences based on marker genes directly from the sample. Due to the manual effort involved, this approach does not scale to multiple metagenome samples and requires substantial expertise, which researchers who are new to the area do not have. Results. We have developed PhyloPythiaS+, a successor to our PhyloPythia(S)…

  43. 43
    top 3.4%

    How smartphone usage correlates with social anxiety and loneliness

    Yusong Gao, Ang Li, Tingshao Zhu, Xiaoqian Liu, Xingyun Liu

    112 citationsOpen access (CC-BY)doi:10.7717/peerj.2197OpenAlex

    Show abstract

    INTRODUCTION: Early detection of social anxiety and loneliness might be useful to prevent substantial impairment in personal relationships. Understanding the way people use smartphones can be beneficial for implementing an early detection of social anxiety and loneliness. This paper examines different types of smartphone usage and their relationships with people with different individual levels of social anxiety or loneliness. METHODS: A total of 127 Android smartphone volunteers participated in this study, all of which have agreed to install an application (MobileSens) on their smartphones, which can record user's smartphone usage behaviors and upload the data into the server. They were instructed to complete an online survey, including the Interaction Anxiousness Scale (IAS) and the University of California Los Angeles Loneliness Scale (UCLA-LS). We then separated participants into three groups (high, middle and low) based on their scores of IAS and UCLA-LS, respectively. Finally, we acquired digital records of smartphone usage from MobileSens and examined the differences in 105…

  44. 44
    top 3.4%

    Tree phyllosphere bacterial communities: exploring the magnitude of intra- and inter-individual variation among host species

    Isabelle Laforest‐Lapointe, Christian Messier, Steven W. Kembel

    111 citationsOpen access (CC-BY)doi:10.7717/peerj.2367OpenAlex

    Show abstract

    BACKGROUND: The diversity and composition of the microbial community of tree leaves (the phyllosphere) varies among trees and host species and along spatial, temporal, and environmental gradients. Phyllosphere community variation within the canopy of an individual tree exists but the importance of this variation relative to among-tree and among-species variation is poorly understood. Sampling techniques employed for phyllosphere studies include picking leaves from one canopy location to mixing randomly selected leaves from throughout the canopy. In this context, our goal was to characterize the relative importance of intra-individual variation in phyllosphere communities across multiple species, and compare this variation to inter-individual and interspecific variation of phyllosphere epiphytic bacterial communities in a natural temperate forest in Quebec, Canada. METHODS: We targeted five dominant temperate forest tree species including angiosperms and gymnosperms: Acer saccharum, Acer rubrum, Betula papyrifera, Abies balsamea and Picea glauca. For one randomly selected tree of…

  45. 45
    top 3.5%

    ProbioticBacillus coagulansGBI-30, 6086 reduces exercise-induced muscle damage and increases recovery

    Ralf Jäger, Kevin A. Shields, Ryan P. Lowery, Eduardo O. De Souza, Jeremy M. Partl and 3 more

    111 citationsOpen access (CC-BY)doi:10.7717/peerj.2276OpenAlex

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    Objective. Probiotics have been reported to support healthy digestive and immune function, aid in protein absorption, and decrease inflammation. Further, a trend to increase vertical jump power has been observed following co-administration of protein and probiotics in resistance-trained subjects. However, to date the potential beneficial effect of probiotics on recovery from high intensity resistance exercise have yet to be explored. Therefore, this study examined the effect of co-administration of protein and probiotics on muscle damage, recovery and performance following a damaging exercise bout. Design. Twenty nine (n = 29) recreationally-trained males (mean ± SD; 21.5 ± 2.8 years; 89.7 ± 28.2 kg; 177.4 ± 8.0 cm) were assigned to consume either 20 g of casein (PRO) or 20 g of casein plus probiotic (1 billion CFU Bacillus coagulans GBI-30, 6086, PROBC) in a crossover, diet-controlled design. After two weeks of supplementation, perceptional measures, athletic performance, and muscle damage were analyzed following a damaging exercise bout. Results. The damaging exercise bout…

  46. 46
    top 3.6%

    Pursuing the quest for better understanding the taxonomic distribution of the system of doubly uniparental inheritance of mtDNA

    Arthur Gusman, Sophia Lecomte, Donald T. Stewart, Marco Passamonti, Sophie Breton

    109 citationsOpen access (CC-BY)doi:10.7717/peerj.2760OpenAlex

    Show abstract

    There is only one exception to strict maternal inheritance of mitochondrial DNA (mtDNA) in the animal kingdom: a system named doubly uniparental inheritance (DUI), which is found in several bivalve species. Why and how such a radically different system of mitochondrial transmission evolved in bivalve remains obscure. Obtaining a more complete taxonomic distribution of DUI in the Bivalvia may help to better understand its origin and function. In this study we provide evidence for the presence of sex-linked heteroplasmy (thus the possible presence of DUI) in two bivalve species, i.e., the nuculanoid Yoldia hyperborea (Gould, 1841) and the veneroid Scrobicularia plana (Da Costa , 1778), increasing the number of families in which DUI has been found by two. An update on the taxonomic distribution of DUI in the Bivalvia is also presented.

  47. 47
    top 3.7%

    Breakdown of coevolution between symbiotic bacteria Wolbachia and their filarial hosts

    Emilie Lefoulon, O. Bain, Benjamin L. Makepeace, Cyrille A. D’Haese, Shigehiko Uni and 2 more

    109 citationsOpen access (CC-BY)doi:10.7717/peerj.1840OpenAlex

    Show abstract

    Wolbachia is an alpha-proteobacterial symbiont widely distributed in arthropods. Since the identification of Wolbachia in certain animal-parasitic nematodes (the Onchocercidae or filariae), the relationship between arthropod and nematode Wolbachia has attracted great interest. The obligate symbiosis in filariae, which renders infected species susceptible to antibiotic chemotherapy, was held to be distinct from the Wolbachia-arthropod relationship, typified by reproductive parasitism. While co-evolutionary signatures in Wolbachia-arthropod symbioses are generally weak, reflecting horizontal transmission events, strict co-evolution between filariae and Wolbachia has been reported previously. However, the absence of close outgroups for phylogenetic studies prevented the determination of which host group originally acquired Wolbachia. Here, we present the largest co-phylogenetic analysis of Wolbachia in filariae performed to date including: (i) a screening and an updated phylogeny of Wolbachia; (ii) a co-phylogenetic analysis; and (iii) a hypothesis on the acquisition of Wolbachia…

  48. 48
    top 3.7%

    Meta-analysis reveals that seed-applied neonicotinoids and pyrethroids have similar negative effects on abundance of arthropod natural enemies

    Margaret R. Douglas, John F. Tooker

    108 citationsOpen access (CC-BY)doi:10.7717/peerj.2776OpenAlex

    Show abstract

    Background Seed-applied neonicotinoids are widely used in agriculture, yet their effects on non-target species remain incompletely understood. One important group of non-target species is arthropod natural enemies (predators and parasitoids), which contribute considerably to suppression of crop pests. We hypothesized that seed-applied neonicotinoids reduce natural-enemy abundance, but not as strongly as alternative insecticide options such as soil- and foliar-applied pyrethroids. Furthermore we hypothesized that seed-applied neonicotinoids affect natural enemies through a combination of toxin exposure and prey scarcity. Methods To test our hypotheses, we compiled datasets comprising observations from randomized field studies in North America and Europe that compared natural-enemy abundance in plots that were planted with seed-applied neonicotinoids to control plots that were either (1) managed without insecticides (20 studies, 56 site-years, 607 observations) or (2) managed with pyrethroid insecticides (eight studies, 15 site-years, 384 observations). Using the effect size Hedge’s d…

  49. 49
    top 3.8%

    Adaptive changes in chlorophyll content and photosynthetic features to low light in Physocarpus amurensis Maxim and Physocarpus opulifolius “Diabolo”

    Huihui Zhang, Haixiu Zhong, Jifeng Wang, Xin Sui, Nan Xu

    107 citationsOpen access (CC-BY)doi:10.7717/peerj.2125OpenAlex

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    The present study aims to investigate the differences in leaf pigment content and the photosynthetic characteristics under natural and low light intensities between the Chinese native Physocarpus amurensis Maxim and the imported Physocarpus opulifolius "Diabolo" from North America. We aim to discuss the responses and the adaptive mechanism of these two cultivars of Physocarpus to a low light environment. The results show that the specific leaf area (SLA) and the chlorophyll content were significantly increased in the leaves of both Physocarpus cultivars in response to a low light intensity, and the SLA and chlorophyll content were higher in the leaves of low light-treated P. opulifolius "Diabolo" compared with the leaves of low light-treated P. amurensis Maxim. Moreover, the content of anthocyanin was markedly reduced in the leaves of P. opulifolius "Diabolo" under low light intensity, which allowed for a greater capacity of photon capture under the low light condition. Under natural light, the photosynthetic carbon assimilation capacity was greater in the leaves of P. amurensis…

  50. 50
    top 3.9%

    Aging and serum MCP-1 are associated with gut microbiome composition in a murine model

    Melissa N. Conley, Carmen P. Wong, Kyle M. Duyck, Norman G. Hord, Emily Ho and 1 more

    107 citationsOpen access (CC-BY)doi:10.7717/peerj.1854OpenAlex

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    Introduction. Age is the primary risk factor for major human chronic diseases, including cardiovascular disorders, cancer, type 2 diabetes, and neurodegenerative diseases. Chronic, low-grade, systemic inflammation is associated with aging and the progression of immunosenescence. Immunosenescence may play an important role in the development of age-related chronic disease and the widely observed phenomenon of increased production of inflammatory mediators that accompany this process, referred to as "inflammaging." While it has been demonstrated that the gut microbiome and immune system interact, the relationship between the gut microbiome and age remains to be clearly defined, particularly in the context of inflammation. The aim of our study was to clarify the associations between age, the gut microbiome, and pro-inflammatory marker serum MCP-1 in a C57BL/6 murine model. Results. We used 16S rRNA gene sequencing to profile the composition of fecal microbiota associated with young and aged mice. Our analysis identified an association between microbiome structure and mouse age and…

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The cohort is every article, review and book chapter OpenAlex attributes to PeerJ with publication year 2016, excluding retracted works and paratext such as editorials and errata. The top 50 by citation count are listed; the percentile is the rank divided by the cohort size. 50 of the 50 entries have an abstract in OpenAlex. Counts were read on 29 October 2026 and will not be updated on this page, so a quoted rank stays verifiable. Full rules on the methodology page.

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