285 research outputs found

    The discovery of <i>Isocrinus</i> cf. <i>robustus</i> from the Lias Group (Lower Jurassic) near Dunrobin Castle, Sutherland, Scotland

    Get PDF
    A single stem section (pluricolumnal) belonging to a post-Palaeozoic crinoid (sea lily) is reported from a small outcrop of Lower Jurassic Lias Group strata exposed in low cliff near Dunrobin Castle. This is the first Jurassic crinoid recorded from Eastern Scotland and the small fragment has enough diagnostic characters to be assigned to the species Isocrinus cf. robustus; a crinoid found commonly in the Lower Jurassic of England. The Scottish form collected has unusual morphology that is atypical of the genus

    Comments on the ophiuroid family Protasteridae and description of a new genus from the Lower Devonian of the Fox Bay Formation, Falkland Islands

    Get PDF
    Asterozoan fossils are comparatively rare in Gondwana compared with Laurentia, especially in the Devonian. We examined the only fossil ophiuroid yet known from the Falkland Islands and assess its significance for the evolution of the clade. This ophiuroid, herein distinguished as a new genus and species, Darwinaster coleenbiggsae, belongs to the same suprageneric group as Protaster, which was established on a series of Middleā€“Upper Ordovician taxa and persisted into the late Palaeozoic remarkably little changed in morphology. This single example is part of a much wider fauna that includes fossils from the Bokkeveld Group, South Africa and the Precordillera of Argentina. Existing palaeobiogeographic reconstructions confirm that these faunas once existed on contiguous terranes and characterized a distinct suite of similar palaeoenvironments within the Malvinokaffric Realm. This study reviews the existing record of Devonian asterozoans and revises Protasteridae

    A new genus of Protasteridae (Ophiuridea) from the Lower Devonian Bokkeveld Group of South Africa

    Get PDF
    Gamiroaster tempestatis, a new genus and species of Palaeozoic ophiuroid, is described from four specimens identified in the Lower DevonianVoorstehoek Formation (Ceres Subgroup, Bokkeveld Group) of SouthAfrica. This ophiuroid belongs the family Protaseridae, a Middleā€“Late Ordovician taxon that continued into the late Palaeozoic. This new ophiuroid forms part of a much wider fauna of the Malvinokaffric Realm, a biogeographical termused to denote the cool- to cold-water, high-latitude endemic, benthic marine, Devonian faunas of southwestern Gondwana, which also includes the invertebrate fossil assemblages of the Argentine Precordillera and the Fox Bay Formation of the Falkland Islands. The specimens were collected from an obrution deposit excavated on Karbonaatjies farm, ~145 km northeast of Cape Town in theWestern Cape. The excavated rock samples contain >700 articulated specimens of Gamiroaster tempestatis that are closely associated with two types of less common mitrate stylophorans. Silicone casts and high-resolution three-dimensional digital models obtained via micro-CT scanning of these mould fossils provided detailed morphological proxies for this taxonomic description.DST-NRF Centre of Excellence, Palaeosciences (CoE-Pal)JNC201

    Developing a selfā€consistent description of Titan's upper atmosphere without hydrodynamic escape

    Full text link
    In this study, we develop a best fit description of Titan's upper atmosphere between 500ā€‰km and 1500 km, using a oneā€dimensional (1ā€D) version of the threeā€dimensional (3ā€D) Titan Global Ionosphereā€Thermosphere Model. For this modeling, we use constraints from several lower atmospheric Cassiniā€Huygens investigations and validate our simulation results against in situ Cassini Ionā€Neutral Mass Spectrometer (INMS) measurements of N 2 , CH 4 , H 2 , 40 Ar, HCN, and the major stable isotopic ratios of 14 N/ 15 N in N 2 . We focus our investigation on aspects of Titan's upper atmosphere that determine the amount of atmospheric escape required to match the INMS measurements: the amount of turbulence, the inclusion of chemistry, and the effects of including a selfā€consistent thermal balance. We systematically examine both hydrodynamic escape scenarios for methane and scenarios with significantly reduced atmospheric escape. Our results show that the optimum configuration of Titan's upper atmosphere is one with a methane homopause near 1000 km and atmospheric escape rates of 1.41ā€“1.47ā€‰Ć—10 11 CH 4 ā€‰m āˆ’2 s āˆ’1 and 1.08ā€‰Ć—10 14 ā€‰H 2 ā€‰m āˆ’2 s āˆ’1 (scaled relative to the surface). We also demonstrate that simulations consistent with hydrodynamic escape of methane systematically produce inferior fits to the multiple validation points presented here. Key Points The methane homopause is most likely near 1000 km altitude Hydrodynamic escape of methane is not required to match INMS Molecular hydrogen is best fit with a methane homopause of 1000 kmPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/108005/1/jgra51076.pd

    Antioxidant Theranostic Copolymer-Mediated Reduction In Oxidative Stress Following Traumatic Brain Injury Improves Outcome In A Mouse Model

    Get PDF
    Following a traumatic brain injury (TBI), excess reactive oxygen species (ROS) and lipid peroxidation products (LPOx) are generated and lead to secondary injury beyond the primary insult. A major limitation of current treatments is poor target engagement, which has prevented success in clinical trials. Thus, nanoparticle-based treatments have received recent attention because of their ability to increase accumulation and retention in damaged brain. Theranostic neuroprotective copolymers (NPC3) containing thiol functional groups can neutralize ROS and LPOx. Immediate administration of NPC3 following injury in a controlled cortical impact (CCI) mouse model provides a therapeutic window in reducing ROS levels at 2.08ā€“20.83 mg kgāˆ’1 in males and 5.52ā€“27.62 mg kgāˆ’1 in females. This NPC3-mediated reduction in oxidative stress improves spatial learning and memory in males, while females show minimal improvement. Notably, NPC3-mediated reduction in oxidative stress prevents the bilateral spread of necrosis in male mice, which is not observed in female mice and likely accounts for the sex-based spatial learning and memory differences. Overall, these findings suggest sex-based differences to oxidative stress scavenger nanoparticle treatments, and a possible upper threshold of antioxidant activity that provides therapeutic benefit in injured brain since female mice benefit from NPC3 treatment to a lesser extent than male mice

    Theranostic Copolymers Neutralize Reactive Oxygen Species and Lipid Peroxidation Products for the Combined Treatment of Traumatic Brain Injury

    Get PDF
    Traumatic brain injury (TBI) results in the generation of reactive oxygen species (ROS) and lipid peroxidation product (LPOx), including acrolein and 4-hydroxynonenal (4HNE). The presence of these biochemical derangements results in neurodegeneration during the secondary phase of the injury. The ability to rapidly neutralize multiple species could significantly improve outcomes for TBI patients. However, the difficulty in creating therapies that target multiple biochemical derangements simultaneously has greatly limited therapeutic efficacy. Therefore, our goal was to design a material that could rapidly bind and neutralize both ROS and LPOx following TBI. To do this, a series of thiol-functionalized biocompatible copolymers based on lipoic acid methacrylate and polyethylene glycol monomethyl ether methacrylate (FW āˆ¼950 Da) (O950) were prepared. A polymerizable gadolinium-DOTA methacrylate monomer (Gd-MA) was also synthesized starting from cyclen to facilitate direct magnetic resonance imaging and in vivo tracking of accumulation. These neuroprotective copolymers (NPCs) were shown to rapidly and effectively neutralize both ROS and LPOx. Horseradish peroxidase absorbance assays showed that the NPCs efficiently neutralized H2O2, while R-phycoerythrin protection assays demonstrated their ability to protect the fluorescent protein from oxidative damage. 1H NMR studies indicated that the thiol-functional NPCs rapidly form covalent bonds with acrolein, efficiently removing it from solution. In vitro cell studies with SH-SY5Y-differentiated neurons showed that NPCs provide unique protection against toxic concentrations of both H2O2and acrolein. NPCs rapidly accumulate and are retained in the injured brain in controlled cortical impact mice and reduce post-traumatic oxidative stress. Therefore, these materials show promise for improved target engagement of multiple biochemical derangements in hopes of improving TBI therapeutic outcomes

    Pahs, Ionized Gas, and Molecular Hydrogen in Brightest Cluster Galaxies of Cool Core Clusters of Galaxies

    Full text link
    We present measurements of 5-25 {\mu}m emission features of brightest cluster galaxies (BCGs) with strong optical emission lines in a sample of 9 cool-core clusters of galaxies observed with the Infrared Spectrograph on board the Spitzer Space Telescope. These systems provide a view of dusty molecular gas and star formation, surrounded by dense, X-ray emitting intracluster gas. Past work has shown that BCGs in cool-core clusters may host powerful radio sources, luminous optical emission line systems, and excess UV, while BCGs in other clusters never show this activity. In this sample, we detect polycyclic aromatic hydrocarbons (PAHs), extremely luminous, rotationally-excited molecular hydrogen line emission, forbidden line emission from ionized gas ([Ne II] and [Ne III]), and infrared continuum emission from warm dust and cool stars. We show here that these BCGs exhibit more luminous forbidden neon and H2 rotational line emission than star-forming galaxies with similar total infrared luminosities, as well as somewhat higher ratios of 70 {\mu}m / 24 {\mu}m luminosities. Our analysis suggests that while star formation processes dominate the heating of the dust and PAHs, a heating process consistent with suprathermal electron heating from the hot gas, distinct from star formation, is heating the molecular gas and contributing to the heating of the ionized gas in the galaxies. The survival of PAHs and dust suggests that dusty gas is somehow shielded from significant interaction with the X-ray gas.Comment: 27 preprint pages, 18 figures, accepted by Astrophysical Journa

    A practical, bioinformatic workflow system for large data sets generated by next-generation sequencing

    Get PDF
    Transcriptomics (at the level of single cells, tissues and/or whole organisms) underpins many fields of biomedical science, from understanding the basic cellular function in model organisms, to the elucidation of the biological events that govern the development and progression of human diseases, and the exploration of the mechanisms of survival, drug-resistance and virulence of pathogens. Next-generation sequencing (NGS) technologies are contributing to a massive expansion of transcriptomics in all fields and are reducing the cost, time and performance barriers presented by conventional approaches. However, bioinformatic tools for the analysis of the sequence data sets produced by these technologies can be daunting to researchers with limited or no expertise in bioinformatics. Here, we constructed a semi-automated, bioinformatic workflow system, and critically evaluated it for the analysis and annotation of large-scale sequence data sets generated by NGS. We demonstrated its utility for the exploration of differences in the transcriptomes among various stages and both sexes of an economically important parasitic worm (Oesophagostomum dentatum) as well as the prediction and prioritization of essential molecules (including GTPases, protein kinases and phosphatases) as novel drug target candidates. This workflow system provides a practical tool for the assembly, annotation and analysis of NGS data sets, also to researchers with a limited bioinformatic expertise. The custom-written Perl, Python and Unix shell computer scripts used can be readily modified or adapted to suit many different applications. This system is now utilized routinely for the analysis of data sets from pathogens of major socio-economic importance and can, in principle, be applied to transcriptomics data sets from any organism
    • ā€¦
    corecore