202 research outputs found

    Is sex necessary?

    Get PDF
    Fungal sexual reproductive modes have markedly high diversity and plasticity, and asexual species have been hypothesized to arise frequently from sexual fungal species. A recent study on the red yeasts provides further support for the notion that sexual ancestors may give rise to shorter-lived asexual species. However, presumed asexual species may also be cryptically sexual, as revealed by other recent studies

    Recovery and nonrecovery of freshwater food webs from the effects of acidification

    Get PDF
    Many previous attempts to understand how ecological networks respond to and recover from environmental stressors have been hindered by poorly resolved and unreplicated food web data. Few studies have assessed how the topological structure of large, replicated collections of food webs recovers from perturbations. We analysed food web data taken from 23 UK freshwaters, sampled repeatedly over 24 years, yielding a collection of 442 stream and lake food webs. Our main goal was to determine the effect of acidity on food web structure and to analyse the way food web structure recovered from the effects of acidity over time. Long-term monotonic reversals of acidification were evident at many of the sites, but the ecological responses were generally far less evident than chemical changes, or absent. Across the acidity gradient, food web linkage density and network efficiency declined with increasing acidity, while node redundancy (i.e. trophic similarity among species within a web) increased. Within individual sites, connectance, linkage density, trophic height, resource vulnerability and network efficiency tended to increase over time as sites recovered from acidification, while consumer generality and node redundancy tended to decrease. There was evidence for a lag in biological recovery, as those sites showing a recovery in both their biology and their chemistry were a nested subset of those which only showed a chemistry trend. These findings support the notion that food web structure is fundamentally altered by acidity, and that inertia within the food web may be hindering biological recovery. This suggestion of lagged recovery highlights the importance of long-term monitoring when assessing the impacts of anthropogenic stressors on the natural world. This temporal dimension, and recognition that species interactions can shape community dynamics, is missing from most national biomonitoring schemes, which often rely on space-for-time proxies

    Foreign body ingestion mimicking irritable bowel syndrome: a case report

    Get PDF
    <p>Abstract</p> <p>Introduction</p> <p>Foreign body ingestion is associated with a variety of symptoms and complications, often mimicking various diseases. This case report describes an unusual presentation following foreign body ingestion.</p> <p>Case presentation</p> <p>A 56-year-old Greek Caucasian woman presented to a primary care setting, in rural Crete, Greece, with complaints of abdominal pain, cramping and bloating, for the last four months. Alternating constipation and diarrhea was reported. The patient had unknowingly ingested a foreign body that resulted in an irritable bowel syndrome-like presentation.</p> <p>Conclusions</p> <p>This case report emphasizes the need for a high index of suspicion from physicians for a wide differential in their approach to abdominal complaints, as well as the importance of an individualized approach to patients in the setting of clinical medicine.</p

    Weighting and indirect effects identify keystone species in food webs

    Get PDF
    Species extinctions are accelerating globally, yet the mechanisms that maintain local biodiversity remain poorly understood. The extinction of species that feed on or are fed on by many others (i.e. ‘hubs’) has traditionally been thought to cause the greatest threat of further biodiversity loss. Very little attention has been paid to the strength of those feeding links (i.e. link weight) and the prevalence of indirect interactions. Here, we used a dynamical model based on empirical energy budget data to assess changes in ecosystem stability after simulating the loss of species according to various extinction scenarios. Link weight and/or indirect effects had stronger effects on food‐web stability than the simple removal of ‘hubs’, demonstrating that both quantitative fluxes and species dissipating their effects across many links should be of great concern in biodiversity conservation, and the potential for ‘hubs’ to act as keystone species may have been exaggerated to date

    Future sea level change from Antarctica's Lambert-Amery glacial system

    Get PDF
    Future global mean sea level (GMSL) change is dependent on the complex response of the Antarctic ice sheet to ongoing changes and feedbacks in the climate system. The Lambert-Amery glacial system has been observed to be stable over the recent period yet is potentially at risk of rapid grounding line retreat and ice discharge given that a significant volume of its ice is grounded below sea level, making its future contribution to GMSL uncertain. Using a regional ice sheet model of the Lambert-Amery system, we find that under a range of future warming and extreme scenarios, the simulated grounding line remains stable and does not trigger rapid mass loss from grounding line retreat. This allows for increased future accumulation to exceed the mass loss from ice dynamical changes. We suggest that the Lambert-Amery glacial system will remain stable or gain ice mass and mitigate a portion of potential future sea level rise over the next 500 years, with a range of +3.6 to −117.5 mm GMSL equivalent

    FORUM: Ecological networks: the missing links in biomonitoring science.

    Get PDF
    Monitoring anthropogenic impacts is essential for managing and conserving ecosystems, yet current biomonitoring approaches lack the tools required to deal with the effects of stressors on species and their interactions in complex natural systems.Ecological networks (trophic or mutualistic) can offer new insights into ecosystem degradation, adding value to current taxonomically constrained schemes. We highlight some examples to show how new network approaches can be used to interpret ecological responses.Synthesis and applications. Augmenting routine biomonitoring data with interaction data derived from the literature, complemented with ground-truthed data from direct observations where feasible, allows us to begin to characterise large numbers of ecological networks across environmental gradients. This process can be accelerated by adopting emerging technologies and novel analytical approaches, enabling biomonitoring to move beyond simple pass/fail schemes and to address the many ecological responses that can only be understood from a network-based perspective

    Type-1 Collagen differentially alters β-catenin accumulation in primary Dupuytren's Disease cord and adjacent palmar fascia cells

    Get PDF
    <p>Abstract</p> <p>Background</p> <p>Dupuytren's Disease (DD) is a debilitating contractile fibrosis of the palmar fascia characterised by excess collagen deposition, contractile myofibroblast development, increased Transforming Growth Factor-β levels and β-catenin accumulation. The aim of this study was to determine if a collagen-enriched environment, similar to <it>in vivo </it>conditions, altered β-catenin accumulation by primary DD cells in the presence or absence of Transforming Growth Factor-β.</p> <p>Methods</p> <p>Primary DD and patient matched, phenotypically normal palmar fascia (PF) cells were cultured in the presence or absence of type-1 collagen and Transforming Growth Factor-β1. β-catenin and ι-smooth muscle actin levels were assessed by western immunoblotting and immunofluorescence microscopy.</p> <p>Results</p> <p>DD cells display a rapid depletion of cellular β-catenin not evident in patient-matched PF cells. This effect was not evident in either cell type when cultured in the absence of type-1 collagen. Exogenous addition of Transforming Growth Factor-β1 to DD cells in collagen culture negates the loss of β-catenin accumulation. Transforming Growth Factor-β1-induced ι-smooth muscle actin, a marker of myofibroblast differentiation, is attenuated by the inclusion of type-1 collagen in cultures of DD and PF cells.</p> <p>Conclusion</p> <p>Our findings implicate type-1 collagen as a previously unrecognized regulator of β-catenin accumulation and a modifier of TGF-β1 signaling specifically in primary DD cells. These data have implications for current treatment modalities as well as the design of <it>in vitro </it>models for research into the molecular mechanisms of DD.</p

    Gene processing control loops suggested by sequencing, splicing, and RNA folding

    Get PDF
    Abstract Background Small RNAs are known to regulate diverse gene expression processes including translation, transcription, and splicing. Among small RNAs, the microRNAs (miRNAs) of 17 to 27 nucleotides (nts) undergo biogeneses including primary transcription, RNA excision and folding, nuclear export, cytoplasmic processing, and then bioactivity as regulatory agents. We propose that analogous hairpins from RNA molecules that function as part of the spliceosome might also be the source of small, regulatory RNAs (somewhat smaller than miRNAs). Results Deep sequencing technology has enabled discovery of a novel 16-nt RNA sequence in total RNA from human brain that we propose is derived from RNU1, an RNA component of spliceosome assembly. Bioinformatic alignments compel inquiring whether the novel 16-nt sequence or its precursor have a regulatory function as well as determining aspects of how processing intersects with the miRNA biogenesis pathway. Specifically, our preliminary in silico investigations reveal the sequence could regulate splicing factor Arg/Ser rich 1 (SFRS1), a gene coding an essential protein component of the spliceosome. All 16-base source sequences in the UCSC Human Genome Browser are within the 14 instances of RNU1 genes listed in wgEncodeGencodeAutoV3. Furthermore, 10 of the 14 instances of the sequence are also within a common 28-nt hairpin-forming subsequence of RNU1. Conclusions An abundant 16-nt RNA sequence is sourced from a spliceosomal RNA, lies in a stem of a predicted RNA hairpin, and includes reverse complements of subsequences of the 3'UTR of a gene coding for a spliceosome protein. Thus RNU1 could function both as a component of spliceosome assembly and as inhibitor of production of the essential, spliceosome protein coded by SFRS1. Beyond this example, a general procedure is needed for systematic discovery of multiple alignments of sequencing, splicing, and RNA folding data

    Prognostic significance of a systemic inflammatory response in patients receiving first-line palliative chemotherapy for recurred or metastatic gastric cancer

    Get PDF
    <p>Abstract</p> <p>Background</p> <p>There is increasing evidence that the presence of an ongoing systemic inflammatory response is associated with poor prognosis in patients with advanced cancers. We evaluated the relationships between clinical status, laboratory factors and progression free survival (PFS), and overall survival (OS) in patients with recurrent or metastatic gastric cancer receiving first-line palliative chemotherapy.</p> <p>Methods</p> <p>We reviewed 402 patients with advanced gastric adenocarcinoma who received first-line palliative chemotherapy from June 2004 and December 2009. Various chemotherapy regimens were used. Eastern Cooperative Oncology Group performance status (ECOG PS), C-reactive protein (CRP), albumin, Glasgow prognostic score (GPS), and clinical factors were recorded immediately prior to first-line chemotherapy. Patients with both an elevated CRP (>1.0 mg/dL) and hypoalbuminemia (<3.5 mg/dL) were assigned a GPS of 2. Patients in whom only one of these biochemical abnormalities was present were assigned a GPS of 1, and patients with a normal CRP and albumin were assigned a score of 0. To evaluate the factors that affected PFS and OS, univariate and multivariate analyses were performed.</p> <p>Results</p> <p>According to multivariate analysis, the factors independently associated with PFS were ECOG PS (HR 1.37, 95% CI 1.02-1.84, <it>P </it>= 0.035), bone metastasis (HR 1.74, 95% CI 1.14-2.65, <it>P </it>= 0.009), and CRP elevation (HR 1.64, 95% CI 1.28-2.09, <it>P </it>= 0.001). The factors independently associated with OS were ECOG PS (HR 1.33, 95% CI 1.01-1.76, <it>P </it>= 0.037), bone metastasis (HR 1.61, 95% CI 1.08-2.39, <it>P </it>= 0.017), and GPS ≥ 1 (HR 1.76, 95% CI 1.41-2.19, <it>P </it>= 0.001).</p> <p>Conclusions</p> <p>The results of this study showed that the presence of a systemic inflammatory response as evidenced by the CRP, GPS was significantly associated with shorter PFS and OS in patients with recurrent or metastatic gastric cancer receiving first-line palliative chemotherapy. Bone metastasis and GPS were very useful indicator for survival in patients with recurrent or metastatic gastric cancer receiving palliative chemotherapy.</p
    • …
    corecore