91 research outputs found

    Fossil Ants (Hymenoptera: Formicidae) of the Middle Eocene Kishenehn Formation

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    A broad range of interesting fossil insects have been discovered recently in Kishenehn Formation shale (middle Eocene, ca. 46 myo) in northwestern Montana, among them a diversity of ant species.  Two hundred forty-nine ant fossils were examined in this study, with 152 them assignable at least to subfamily.  Here, twelve fossil ant species are formally described.  These include a new genus of Dolichoderinae (Ktunaxia, gen. nov.), and the oldest known species from two extant genera: Crematogaster (C. aurora, sp. nov.) and Pseudomyrmex (P. saxulum, sp. nov.).  The Eocene is of particular interest for understanding ant evolution because it is during this period that many present-day speciose and ecologically dominant clades of ants apparently emerged.  In order to understand the evolution of ants, and in particular their march to the terrestrial dominance observed in modern times, it is critical to understand the tempo of ant diversity during the Eocene.  The Kishenehn provides another window into Eocene ant diversity; its relevance to some of the other major Eocene ant fossil deposits is discussed

    A new aneuretine ant from the Paleocene Paskapoo Formation of Canada

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    While ants were present in the Cretaceous they were relatively rare. This changes dramatically from the Eocene onward when ants rise to the levels of global dominance seen in terrestrial ecosystems today. Their prevalence is well documented in various Eocene, Oligocene, and Miocene fossil deposits, but there is a conspicuous absence of ant-bearing fossil deposits around the Cretaceous–Paleogene boundary. In particular, until this study, there were no definitive ant-yielding deposits between 78 million and 55 million years ago, a 23-million-year gap. This gap is significant because, in addition to spanning a time when ant prevalence increases by an order of magnitude, the fossil rich deposits from the Eocene onward reveal a dramatically different ant fauna from that observed in the Mesozoic. The Paleocene Paskapoo Formation in Alberta, Canada has yielded a variety of fossil arthropod specimens, including a single worker ant fossil. Examination of this fossil indicates it is a species belonging to the now monotypic and relictual ant subfamily Aneuretinae. Napakimyrma paskapooensis gen et. sp. nov. is here described, revealing a species exhibiting a number of interesting and unique morphological features. Its placement as an aneuretine is supported by the presence of a long anterior peduncle of the petiole. A total of 11 fossil aneuretine taxa are now known, but for several, their placement within the subfamily is highly uncertain and needs further study. A discussion of all fossil aneuretine taxa is provided. Given the uncertainty of the apomorphies defining the Aneuretinae, and the fact that fossil species suggest a greater historic morphological diversity for the subfamily than is present now in the single, living species, it is important to consider the need for flexibility in defining synapomorphies for Aneuretinae and any such analysis will need to involve reevaluation of the fossil fauna

    Taxonomic review of the ant genus Paratrechina, with a description of a new species from Africa

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    With the recent finding of Paratrechina (broad sense) paraphyly, only Paratrechina longicornis remained in a redefined genus. As one of the most widely distributed ant species due to human transfer around the world, there is much interest in the biology of P. longicornis. One issue concerning P. longicornis has been as to where exactly the species is native, with both African and Asian native ranges being invoked in the literature. Here we report the discovery of a second species within Paratrechina. This species, P. zanjensis, is native to Africa (known from Angola, Mozambique and Tanzania), where it appears to be a dry miombo woodland species. Given the discovery of this new species, a reevaluation of the morphological definition of Paratrechina is provided; also provided is an updated generic level identification key. Given the available distribution information on P. longicornis, we conclude that P. longicornis remains most likely native to southeastern Asia, and that the discovery of a new species native to Africa makes Paratrechina yet another example of an ant genus that possesses an Afro-Asian distribution.This study was supported in part by the National Science Foundation under grants DEB- 0743542 (awarded to JSL).http://www.pensoft.net/journals/jhram201

    Monograph of Nylanderia (Hymenoptera: Formicidae) of the world, Part I : Nylanderia in the Afrotropics

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    The taxonomy of the Afrotropical Nylanderia fauna is revised for the first time. Fourteen native species are revealed, of which eight are described as new: N. boltoni LaPolla and Fisher, N. brevisetula LaPolla and Fisher, N. impolita LaPolla and Fisher, N. luteafra LaPolla and Fisher, N. scintilla LaPolla and Fisher, N. silvula LaPolla and Fisher, N. umbella LaPolla and Fisher, and N. usambarica LaPolla, Hawkes and Fisher. Two species, N. jaegerskioeldi and N. natalensis, have workers that are indistinguishable from each other, and males are the only reliable way to separate these two species. Three non-native Nylanderia species are thought to have been introduced to Africa: N. bourbonica, N. vaga, and N. vividula. An identification key to the worker caste is provided.Funds for JSL to travel to Tanzania were provided in part by the Towson University Office of University Research Services through a faculty development grant. This research was supported by the National Science Foundation under grant no. DEB-0743542 awarded to JSL. Funding in support of this research was provided to BLF by WWF-US and National Science Foundation under Grant No. INT 9998672 and DEB-0344731.http://www.mapress.com/zootaxa/ab201

    Isolation and characterization of Nylanderia fulva virus 1, a positive-sense, single-stranded RNA virus infecting the tawny crazy ant, Nylanderia fulva.

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    We report the discovery of Nylanderia fulva virus 1 (NfV-1), the first virus identified and characterized from the ant, Nylanderia fulva. The NfV-1 genome (GenBank accession KX024775) is 10,881 nucleotides in length, encoding one large open reading frame (ORF). Helicase, protease, RNA-dependent RNA polymerase, and jelly-roll capsid protein domains were recognized within the polyprotein. Phylogenetic analysis placed NfV-1 in an unclassified clade of viruses. Electron microscopic examination of negatively stained samples revealed particles with icosahedral symmetry with a diameter of 28.7±1.1nm. The virus was detected by RT-PCR in larval, pupal, worker and queen developmental stages. However, the replicative strand of NfV-1 was only detected in larvae. Vertical transmission did not appear to occur, but horizontal transmission was facile. The inter-colonial field prevalence of NfV-1 was 52±35% with some local infections reaching 100%. NfV-1 was not detected in limited samples of other Nylanderia species or closely related ant species.JSL was supported by the National Science Foundation under Grant DEB-0743542. AEF is supported by the Wellcome Trust (Grant no. [106207]) and the European Research Council (ERC) under the European Union׳s Horizon 2020 research and innovation programme (Grant agreement no. [646891]).This is the final version of the article. It first appeared from Elsevier at https://doi.org/10.1016/j.virol.2016.06.014

    Planck pre-launch status: calibration of the Low Frequency Instrument flight model radiometers

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    The Low Frequency Instrument (LFI) on-board the ESA Planck satellite carries eleven radiometer subsystems, called Radiometer Chain Assemblies (RCAs), each composed of a pair of pseudo-correlation receivers. We describe the on-ground calibration campaign performed to qualify the flight model RCAs and to measure their pre-launch performances. Each RCA was calibrated in a dedicated flight-like cryogenic environment with the radiometer front-end cooled to 20K and the back-end at 300K, and with an external input load cooled to 4K. A matched load simulating a blackbody at different temperatures was placed in front of the sky horn to derive basic radiometer properties such as noise temperature, gain, and noise performance, e.g. 1/f noise. The spectral response of each detector was measured as was their susceptibility to thermal variation. All eleven LFI RCAs were calibrated. Instrumental parameters measured in these tests, such as noise temperature, bandwidth, radiometer isolation, and linearity, provide essential inputs to the Planck-LFI data analysis.Comment: 15 pages, 18 figures. Accepted for publication in Astronomy and Astrophysic

    An ant genus-group ( Prenolepis ) illuminates the biogeography and drivers of insect diversification in the Indo-Pacific

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    The Malay Archipelago and the tropical South Pacific (hereafter the Indo-Pacific region) are considered biodiversity hotspots, yet a general understanding of the origins and diversification of species-rich groups in the region remains elusive. We aimed to test hypotheses for the evolutionary processes driving insect species diversity in the Indo-Pacific using a higher-level and comprehensive phylogenetic hypothesis for an ant clade consisting of seven genera. We estimated divergence times and reconstructed the biogeographical history of ant species in the Prenolepis genus-group (Formicidae: Formicinae: Lasiini). We used a fossil-calibrated phylogeny to infer ancestral geographical ranges utilizing a biogeographic model that includes founder-event speciation. Ancestral state reconstructions of the ants\u27 ecological preferences, and diversification rates were estimated for selected Indo-Pacific clades. Overall, we report that faunal interchange between Asia and Australia has occurred since at least 20–25 Ma, and early dispersal to the Fijian Basin happened during the early and mid-Miocene (ca. 10–20 Ma). Differences in diversification rates across Indo-Pacific clades may be related to ecological preference breadth, which in turn may have facilitated geographical range expansions. Ancient dispersal routes suggested by our results agree with the palaeogeography of the region. For this particular group of ants, the rapid orogenesis in New Guinea and possibly subsequent ecological shifts may have promoted their rapid diversification and widespread distribution across the Indo-Pacific

    Evaluation of the impact of universal testing for gestational diabetes mellitus on maternal and neonatal health outcomes: a retrospective analysis

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    Background: Gestational diabetes (GDM) affects a substantial proportion of women in pregnancy and is associated with increased risk of adverse perinatal and long term outcomes. Treatment seems to improve perinatal outcomes, the relative effectiveness of different strategies for identifying women with GDM however is less clear. This paper describes an evaluation of the impact of a change in policy from selective risk factor based offering, to universal offering of an oral glucose tolerance test (OGTT) to identify women with GDM on maternal and neonatal outcomes. Methods: Retrospective six year analysis of 35,674 births at the Women’s and Newborn unit, Bradford Royal Infirmary, United Kingdom. Results: The proportion of the whole obstetric population diagnosed with GDM increased almost fourfold following universal offering of an OGTT compared to selective offering of an OGTT; Rate Ratio (RR) 3.75 (95% CI 3.28 to 4.29), the proportion identified with severe hyperglycaemia doubled following the policy change; 1.96 (1.50 to 2.58). The case detection rate however, for GDM in the whole population and severe hyperglycaemia in those with GDM reduced by 50-60%; 0.40 (0.35 to 0.46) and 0.51 (0.39 to 0.67) respectively. Universally offering an OGTT was associated with an increased induction of labour rate in the whole obstetric population and in women with GDM; 1.43 (1.35 to 1.50) and 1.21 (1.00 to1.49) respectively. Caesarean section, macrosomia and perinatal mortality rates in the whole population were similar. For women with GDM, rate of caesarean section; 0.70 (0.57 to 0.87), macrosomia; 0.22 (0.15 to 0.34) and perinatal mortality 0.12 (0.03 to 0.46) decreased following the policy change. Conclusions: Universally offering an OGTT was associated with increased identification of women with GDM and severe hyperglycaemia and with neonatal benefits for those with GDM. There was no evidence of benefit or adverse effects in neonatal outcomes in the whole obstetric population

    Biogeography of mutualistic fungi cultivated by leafcutter ants

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    Leafcutter ants propagate co-evolving fungi for food. The nearly 50 species of leafcutter ants (Atta, Acromyrmex) range from Argentina to the United States, with the greatest species diversity in southern South America. We elucidate the biogeography of fungi cultivated by leafcutter ants using DNA sequence and microsatellite-marker analyses of 474 cultivars collected across the leafcutter range. Fungal cultivars belong to two clades (Clade-A and Clade-B). The dominant and widespread Clade-A cultivars form three genotype clusters, with their relative prevalence corresponding to southern South America, northern South America, Central and North America. Admixture between Clade-A populations supports genetic exchange within a single species, Leucocoprinus gongylophorus. Some leafcutter species that cut grass as fungicultural substrate are specialized to cultivate Clade-B fungi, whereas leafcutters preferring dicot plants appear specialized on Clade-A fungi. Cultivar sharing between sympatric leafcutter species occurs frequently such that cultivars of Atta are not distinct from those of Acromyrmex. Leafcutters specialized on Clade-B fungi occur only in South America. Diversity of Clade-A fungi is greatest in South America, but minimal in Central and North America. Maximum cultivar diversity in South America is predicted by the Kusnezov–Fowler hypothesis that leafcutter ants originated in subtropical South America and only dicot-specialized leafcutter ants migrated out of South America, but the cultivar diversity becomes also compatible with a recently proposed hypothesis of a Central American origin by postulating that leafcutter ants acquired novel cultivars many times from other nonleafcutter fungus-growing ants during their migrations from Central America across South America. We evaluate these biogeographic hypotheses in the light of estimated dates for the origins of leafcutter ants and their cultivars

    Twelve-month observational study of children with cancer in 41 countries during the COVID-19 pandemic

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    Introduction Childhood cancer is a leading cause of death. It is unclear whether the COVID-19 pandemic has impacted childhood cancer mortality. In this study, we aimed to establish all-cause mortality rates for childhood cancers during the COVID-19 pandemic and determine the factors associated with mortality. Methods Prospective cohort study in 109 institutions in 41 countries. Inclusion criteria: children <18 years who were newly diagnosed with or undergoing active treatment for acute lymphoblastic leukaemia, non-Hodgkin's lymphoma, Hodgkin lymphoma, retinoblastoma, Wilms tumour, glioma, osteosarcoma, Ewing sarcoma, rhabdomyosarcoma, medulloblastoma and neuroblastoma. Of 2327 cases, 2118 patients were included in the study. The primary outcome measure was all-cause mortality at 30 days, 90 days and 12 months. Results All-cause mortality was 3.4% (n=71/2084) at 30-day follow-up, 5.7% (n=113/1969) at 90-day follow-up and 13.0% (n=206/1581) at 12-month follow-up. The median time from diagnosis to multidisciplinary team (MDT) plan was longest in low-income countries (7 days, IQR 3-11). Multivariable analysis revealed several factors associated with 12-month mortality, including low-income (OR 6.99 (95% CI 2.49 to 19.68); p<0.001), lower middle income (OR 3.32 (95% CI 1.96 to 5.61); p<0.001) and upper middle income (OR 3.49 (95% CI 2.02 to 6.03); p<0.001) country status and chemotherapy (OR 0.55 (95% CI 0.36 to 0.86); p=0.008) and immunotherapy (OR 0.27 (95% CI 0.08 to 0.91); p=0.035) within 30 days from MDT plan. Multivariable analysis revealed laboratory-confirmed SARS-CoV-2 infection (OR 5.33 (95% CI 1.19 to 23.84); p=0.029) was associated with 30-day mortality. Conclusions Children with cancer are more likely to die within 30 days if infected with SARS-CoV-2. However, timely treatment reduced odds of death. This report provides crucial information to balance the benefits of providing anticancer therapy against the risks of SARS-CoV-2 infection in children with cancer
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