72 research outputs found
Redating the earliest evidence of the mid-Holocene relative sea-level highstand in Australia and implications for global sea-level rise.
Reconstructing past sea levels can help constrain uncertainties surrounding the rate of change, magnitude, and impacts of the projected increase through the 21st century. Of significance is the mid-Holocene relative sea-level highstand in tectonically stable and remote (far-field) locations from major ice sheets. The east coast of Australia provides an excellent arena in which to investigate changes in relative sea level during the Holocene. Considerable debate surrounds both the peak level and timing of the east coast highstand. The southeast Australian site of Bulli Beach provides the earliest evidence for the establishment of a highstand in the Southern Hemisphere, although questions have been raised about the pretreatment and type of material that was radiocarbon dated for the development of the regional sea-level curve. Here we undertake a detailed morpho- and chronostratigraphic study at Bulli Beach to better constrain the timing of the Holocene highstand in eastern Australia. In contrast to wood and charcoal samples that may provide anomalously old ages, probably due to inbuilt age, we find that short-lived terrestrial plant macrofossils provide a robust chronological framework. Bayesian modelling of the ages provide improved dating of the earliest evidence for a highstand at 6,880±50 cal BP, approximately a millennium later than previously reported. Our results from Bulli now closely align with other sea-level reconstructions along the east coast of Australia, and provide evidence for a synchronous relative sea-level highstand that extends from the Gulf of Carpentaria to Tasmania. Our refined age appears to be coincident with major ice mass loss from Northern Hemisphere and Antarctic ice sheets, supporting previous studies that suggest these may have played a role in the relative sea-level highstand. Further work is now needed to investigate the environmental impacts of regional sea levels, and refine the timing of the subsequent sea-level fall in the Holocene and its influence on coastal evolution
Microsurgical and tractographic anatomical study of insular and transsylvian transinsular approach
This study is to define the operative anatomy of the insula with emphasis on the transsylvian transinsular approach. The anatomy was studied in 15 brain specimens, among five were dissected by use of fiber dissection technique; diffusion tensor imaging of 10 healthy volunteers was obtained with a 1.5-T MR system. The temporal stem consists mainly of the uncinate fasciculus, inferior occipitofrontal fasciculus, Meyer’s loop of the optic radiation and anterior commissure. The transinsular approach requires an incision of the inferior limiting sulcus. In this procedure, the fibers of the temporal stem can be interrupted to various degrees. The fiber dissection technique is a very relevant and reliable method for neurosurgeons to study the details of brain anatomic features. The DTI fiber tracking technique can identify the fiber tracts of the temporal stem. Moreover, it will also help further functional study of human insula
Towards improving the safety and diagnostic yield of stereotactic biopsy in a single centre
Background: Previously, we reported on our single centre results regarding the diagnostic yield of stereotactic needle biopsies of brain lesions. The yield then (1996-2006) was 89.4%. In the present study, we review and evaluate our experience with intraoperative frozen-section histopathologic diagnosis on-demand in order to improve the diagnostic yield. Methods:
Species difference in ANP32A underlies influenza A virus polymerase host restriction.
Influenza pandemics occur unpredictably when zoonotic influenza viruses with novel antigenicity acquire the ability to transmit amongst humans. Host range breaches are limited by incompatibilities between avian virus components and the human host. Barriers include receptor preference, virion stability and poor activity of the avian virus RNA-dependent RNA polymerase in human cells. Mutants of the heterotrimeric viral polymerase components, particularly PB2 protein, are selected during mammalian adaptation, but their mode of action is unknown. We show that a species-specific difference in host protein ANP32A accounts for the suboptimal function of avian virus polymerase in mammalian cells. Avian ANP32A possesses an additional 33 amino acids between the leucine-rich repeats and carboxy-terminal low-complexity acidic region domains. In mammalian cells, avian ANP32A rescued the suboptimal function of avian virus polymerase to levels similar to mammalian-adapted polymerase. Deletion of the avian-specific sequence from chicken ANP32A abrogated this activity, whereas its insertion into human ANP32A, or closely related ANP32B, supported avian virus polymerase function. Substitutions, such as PB2(E627K), were rapidly selected upon infection of humans with avian H5N1 or H7N9 influenza viruses, adapting the viral polymerase for the shorter mammalian ANP32A. Thus ANP32A represents an essential host partner co-opted to support influenza virus replication and is a candidate host target for novel antivirals
Several Distinct Polycomb Complexes Regulate and Co-Localize on the INK4a Tumor Suppressor Locus
Misexpression of Polycomb repressive complex 1 (PRC1) components in human cells profoundly influences the onset of cellular senescence by modulating transcription of the INK4a tumor suppressor gene. Using tandem affinity purification, we find that CBX7 and CBX8, two Polycomb (Pc) homologs that repress INK4a, both participate in PRC1-like complexes with at least two Posterior sex combs (Psc) proteins, MEL18 and BMI1. Each complex contains a single representative of the Pc and Psc families. In primary human fibroblasts, CBX7, CBX8, MEL18 and BMI1 are present at the INK4a locus and shRNA-mediated knockdown of any one of these components results in de-repression of INK4a and proliferative arrest. Sequential chromatin immunoprecipitation (ChIP) reveals that CBX7 and CBX8 bind simultaneously to the same region of chromatin and knockdown of one of the Pc or Psc proteins results in release of the other, suggesting that the binding of PRC1 complexes is interdependent. Our findings provide the first evidence that a single gene can be regulated by several distinct PRC1 complexes and raise important questions about their configuration and relative functions
The Role of bZIP Transcription Factors in Green Plant Evolution: Adaptive Features Emerging from Four Founder Genes
BACKGROUND: Transcription factors of the basic leucine zipper (bZIP) family control important processes in all eukaryotes. In plants, bZIPs are regulators of many central developmental and physiological processes including photomorphogenesis, leaf and seed formation, energy homeostasis, and abiotic and biotic stress responses. Here we performed a comprehensive phylogenetic analysis of bZIP genes from algae, mosses, ferns, gymnosperms and angiosperms. METHODOLOGY/PRINCIPAL FINDINGS: We identified 13 groups of bZIP homologues in angiosperms, three more than known before, that represent 34 Possible Groups of Orthologues (PoGOs). The 34 PoGOs may correspond to the complete set of ancestral angiosperm bZIP genes that participated in the diversification of flowering plants. Homologous genes dedicated to seed-related processes and ABA-mediated stress responses originated in the common ancestor of seed plants, and three groups of homologues emerged in the angiosperm lineage, of which one group plays a role in optimizing the use of energy. CONCLUSIONS/SIGNIFICANCE: Our data suggest that the ancestor of green plants possessed four bZIP genes functionally involved in oxidative stress and unfolded protein responses that are bZIP-mediated processes in all eukaryotes, but also in light-dependent regulations. The four founder genes amplified and diverged significantly, generating traits that benefited the colonization of new environments
Whole-genome sequences of Malawi cichlids reveal multiple radiations interconnected by gene flow.
The hundreds of cichlid fish species in Lake Malawi constitute the most extensive recent vertebrate adaptive radiation. Here we characterize its genomic diversity by sequencing 134 individuals covering 73 species across all major lineages. The average sequence divergence between species pairs is only 0.1-0.25%. These divergence values overlap diversity within species, with 82% of heterozygosity shared between species. Phylogenetic analyses suggest that diversification initially proceeded by serial branching from a generalist Astatotilapia-like ancestor. However, no single species tree adequately represents all species relationships, with evidence for substantial gene flow at multiple times. Common signatures of selection on visual and oxygen transport genes shared by distantly related deep-water species point to both adaptive introgression and independent selection. These findings enhance our understanding of genomic processes underlying rapid species diversification, and provide a platform for future genetic analysis of the Malawi radiation
Subakute transversale Myelitis mit unterschiedlichen Lyme-Profilen
Introduction: Transverse myelitis is a very rare neurologic syndrome with an incidence per year of 1-5 per million population. We are presenting an interesting case of subacute transverse myelitis with its MRI (magnetic resonance imaging) and CSF (cerebrospinal fluid) findings. Case: A 46-year-old African-American woman presented with decreased sensation in the lower extremities which started three weeks ago when she had a 36-hour episode of sore throat. She reported numbness up to the level just below the breasts. Lyme disease antibodies total IgG (immunoglobulin G) and IgM (immunoglobulin M) in the blood was positive. Antinuclear antibody profile was within normal limits. MRI of the cervical spine showed swelling in the lower cervical cord with contrast enhancement. Cerebrospinal fluid was clear with negative Borrelia Burgdorferi IgG and IgM. Herpes simplex, mycoplasma, coxiella, anaplasma, cryptococcus and hepatitis B were all negative. No oligoclonal bands were detected. Quick improvement ensued after she was given IV Ceftriaxone for 7 days. The patient was discharged on the 8th day in stable condition. She continued on doxycycline for 21 days. Conclusions: Transverse myelitis should be included in the differential diagnosis of any patient presenting with acute or subacute myelopathy in association with localized contrast enhancement in the spinal cord especially if flu-like prodromal symptoms were reported. Lyme disease serology is indicated in patients with neurological symptoms keeping in mind that dissociation in Lyme antibody titers between the blood and the CSF is possible.Einleitung: Die transversale Myelitis ist eine seltene neurologische Erkrankung mit einer Häufigkeit von 1-5 pro 1 Mio. Bevölkerung und Jahr. Wir stellen einen interessanten Fall einer subakuten transversalen Myelitis zusammen mit Magnetresonanztomographie und Liquorbefunden vor. Fallbeschreibung: Eine 46-jährige Frau afrikanisch-amerikanischer Herkunft beklagte eine verminderte Sensibilität in den unteren Extremitäten, die drei Wochen vorher entstanden war, nachdem eine 36-stündige Phase mit trockenem Hals vorausgegangen war. Sie berichtete über Gefühllosigkeit bis hinauf im Brustbereich. Die Lyme-Antikörper IgG und IgM waren im Blut positiv. Die antinucleären Antikörper lagen im normalen Bereich. Die Magnetresonanztomographie des zervikalen Rückenmarks zeigte eine Anschwellung im unteren zervikalen Rückenmarkbereich mit erhöhtem Kontrast. Der Liquor war klar, der Test auf Borrelia Burgdorferi IgG und IgM war negativ. Herpes simplex-, Mycoplasma-, Coxiella-, Anaplasma-, Cryptococcus- und Hepatits B-Tests waren alle negativ. Oligoklonale Banden konnten nicht nachgewiesen werden. Eine rasche Besserung erfolgte, als sie 7 Tage lang Ceftriaxon intravenös erhielt. Die Patientin wurde am 8. Tag entlassen in stabilisiertem Zustand. Über weitere 21 Tage nahm sie Doxycycline ein. Schlussfolgerung: Die transversale Myelitis sollte in die Differenzialdiagnose bei Patienten einbezogen werden, die akute oder subakute Myelopathien in Verbindung mit lokalisierter Kontrastverstärkung im Rückenmark aufweisen, insbesondere wenn auch von grippeähnlichen Symptomen berichtet wird. Die Lyme-Serologie ist bei Patienten mit neurologischen Symptomen angezeigt, wobei zu bedenken ist, dass bei den Lyme-Antikörper-Titern Unterschiede zwischen Blut und Liquor auftreten können
Marine carbon reservoir variability in Torres Strait: preliminary results of AMS dating of live-collected shell specimens.
Despite routine dating of marine shell by Quaternary scientists in the Torres Strait region, no systematic evaluation of the applicability of the recommended DeltaR value has been undertaken. This value can be shown to be problematic. It is based on only three samples from Torres Strait and two from the west coast of Cape York Peninsula, together spanning 125±60 to -14±60 years; the samples are from different oceanographic provinces; the dated taxa are not amongst those commonly dated by contemporary researchers; and all of the dates were obtained over 20 years ago before the advent of high precision AMS dating. This project attempts to address this deficiency through the dating of a suite of well-provenanced live-collected shell specimens using the high precision ANTARES AMS facilities at ANSTO. Dated samples are largely derived from a unique assemblage of well-documented live-collected shell specimens in the Australian Museum from Murray Island and Albany Passage collected by Charles Hedley in August-October 1907, supplemented by smaller collections from elsewhere in Torres Strait. Sample selection focused on suspension-feeders (Arcidae, Mesodesmatidae, Veneridae), although carnivores (Volutidae), herbivores/omnivores (Neritidae) and algae grazers (Trochidae) were included to examine inter-taxa variability. Preliminary results help establish more robust regional DeltaR values for the region based on shellfish commonly dated by Quaternary scientists and allow examination of localised variability in DeltaR values. These findings have broad implications for refining chronologies in coastal archaeology and geomorphology in the Torres Strait region, including studies of sea-level change, reef and coral cay development, coastal dune sequences, storm event frequency and archaeological trends.International Union for Quaternary Researc
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