Genomic Mining for Aspergillus Natural Products

SummaryThe genus Aspergillus is renowned for its ability to produce a myriad of bioactive secondary metabolites. Although the propensity of biosynthetic genes to form contiguous clusters greatly facilitates assignment of putative secondary metabolite genes in the completed Aspergillus genomes, such analysis cannot predict gene expression and, ultimately, product formation. To circumvent this deficiency, we have examined Aspergillus nidulans microarrays for expressed secondary metabolite gene clusters by using the transcriptional regulator LaeA. Deletion or overexpression of laeA clearly identified numerous secondary metabolite clusters. A gene deletion in one of the clusters eliminated the production of the antitumor compound terrequinone A, a metabolite not described, from A. nidulans. In this paper, we highlight that LaeA-based genome mining helps decipher the secondary metabolome of Aspergilli and provides an unparalleled view to assess secondary metabolism gene regulation

High Pressure Assisted Coronary Stent Implantation Accomplished Without Intravascular Ultrasound Guidance and Subsequent Anticoagulation

AbstractObjectives. The purpose of this study was to determine the efficacy of treatment with antiplatelet therapy and no anticoagulation after high pressure assisted coronary stent implantation performed without intravascular ultrasound (IVUS) guidance.Background. Previous studies have shown that during IVUS-guided Palmaz-Schatz coronary stenting, it is safe to withhold anticoagulation when stent expansion has been optimized by high pressure balloon dilation.Methods. Patients that had successful coronary stenting without IVUS guidance were treated with ticlopidine, 500 mg/day, and aspirin, 325 mg/day, for 1 month and then received only aspirin, 325 mg/day, indefinitely. Patients were not treated with warfarin (Coumadin) or heparin after successful stenting. Clinical and angiographic events were assessed at 1 month.Results. A total of 201 intracoronary stents were implanted in 127 patients with 137 lesions. The average number of stents per lesion was 1.4 ± 0.8, and the average number of stents per patient was 1.6 ± 1.1. Stent deployment was performed for elective indications in 79% of procedures and for emergency indications in 21%. There were four stent thrombosis events for a per patient event rate of 3.1% and a per lesion event rate of 2.9%.Conclusions. After high pressure assisted stenting performed without IVUS guidance, there was an acceptable incidence of 3.1% of stent thrombosis with the combination of short-term ticlopidine and aspirin therapy and no anticoagulation. Although the study involved only 127 patients, the results support the relative safety of stenting without IVUS guidance and with antiplatelet therapy only in comparison to historical trials on stenting performed with postprocedure anticoagulation.(J Am Coll Cardiol 1977;29:21–7)

On detectability of Zeeman broadening in optical spectra of F- and G-dwarfs

We investigate the detectability of Zeeman broadening in optical Stokes I spectra of slowly rotating sun-like stars. To this end, we apply the LTE spectral line inversion package SPINOR to very-high quality CES data and explore how fit quality depends on the average magnetic field, Bf . One-component (OC) and two-component (TC) models are adopted. In OC models, the entire surface is assumed to be magnetic. Under this assumption, we determine formal 3{\sigma} upper limits on the average magnetic field of 200 G for the Sun, and 150 G for 61 Vir (G6V). Evidence for an average magnetic field of ~ 500 G is found for 59 Vir (G0V), and of ~ 1000 G for HD 68456 (F6V). A distinction between magnetic and non-magnetic regions is made in TC models, while assuming a homogeneous distribution of both components. In our TC inversions of 59 Vir, we investigate three cases: both components have equal temperatures; warm magnetic regions; cool magnetic regions. Our TC model with equal temperatures does not yield significant improvement over OC inversions for 59 Vir. The resulting Bf values are consistent for both. Fit quality is significantly improved, however, by using two components of different temperatures. The inversions for 59 Vir that assume different temperatures for the two components yield results consistent with 0 - 450 G at the formal 3{\sigma} confidence level. We thus find a model dependence of our analysis and demonstrate that the influence of an additional temperature component can dominate over the Zeeman broadening signature, at least in optical data. Previous comparable analyses that neglected effects due to multiple temperature components may be prone to the same ambiguities.Comment: 18 pages, 11 figures, accepted for publication in Astronomy & Astrophysic

Peer teaching and information retrieval: the role of the NICE Evidence search student champion scheme in enhancing students’ confidence

Background This research reports on the NICE Evidence search (ES) student champion scheme (SCS) first five years of activity (2011–2016) in terms of its impact on health care undergraduate students’ information search skills and search confidence. Objectives A review of students’ evaluation of the scheme was carried out to chart the changes in attitude towards NICE Evidence search as an online health care information source and to monitor students’ approach to information seeking. Methods This study is based on the results of questionnaires distributed to students before and after attending a training session on NICE Evidence search delivered by their own peers. The exercise was implemented in health related universities in England over a period of five consecutive academic years. Results (i) Students’ search confidence improved considerably after the training; (ii) ES was perceived as being an increasingly useful resource of evidence based information for their studies; (iii) the training helped students develop discerning search skills and use evidence based information sources more consistently and critically. Conclusions The NICE SCS improves confidence in approaching information tasks amongst health care undergraduate students. Future developments could involve offering the training at the onset of a course of study and adopting online delivery formats to expand its geographical reach

Diversity and dispersal of a ubiquitous protein family: acyl-CoA dehydrogenases

Acyl-CoA dehydrogenases (ACADs), which are key enzymes in fatty acid and amino acid catabolism, form a large, pan-taxonomic protein family with at least 13 distinct subfamilies. Yet most reported ACAD members have no subfamily assigned, and little is known about the taxonomic distribution and evolution of the subfamilies. In completely sequenced genomes from approximately 210 species (eukaryotes, bacteria and archaea), we detect ACAD subfamilies by rigorous ortholog identification combining sequence similarity search with phylogeny. We then construct taxonomic subfamily-distribution profiles and build phylogenetic trees with orthologous proteins. Subfamily profiles provide unparalleled insight into the organisms’ energy sources based on genome sequence alone and further predict enzyme substrate specificity, thus generating explicit working hypotheses for targeted biochemical experimentation. Eukaryotic ACAD subfamilies are traditionally considered as mitochondrial proteins, but we found evidence that in fungi one subfamily is located in peroxisomes and participates in a distinct β-oxidation pathway. Finally, we discern horizontal transfer, duplication, loss and secondary acquisition of ACAD genes during evolution of this family. Through these unorthodox expansion strategies, the ACAD family is proficient in utilizing a large range of fatty acids and amino acids—strategies that could have shaped the evolutionary history of many other ancient protein families

Absolute oxygen-guided radiation therapy improves tumor control in three preclinical tumor models

BackgroundClinical attempts to find benefit from specifically targeting and boosting resistant hypoxic tumor subvolumes have been promising but inconclusive. While a first preclinical murine tumor type showed significant improved control with hypoxic tumor boosts, a more thorough investigation of efficacy from boosting hypoxic subvolumes defined by electron paramagnetic resonance oxygen imaging (EPROI) is necessary. The present study confirms improved hypoxic tumor control results in three different tumor types using a clonogenic assay and explores potential confounding experimental conditions.Materials and methodsThree murine tumor models were used for multi-modal imaging and radiotherapy: MCa-4 mammary adenocarcinomas, SCC7 squamous cell carcinomas, and FSa fibrosarcomas. Registered T2-weighted MRI tumor boundaries, hypoxia defined by EPROI as pO2 ≤ 10 mmHg, and X-RAD 225Cx CT boost boundaries were obtained for all animals. 13 Gy boosts were directed to hypoxic or equal-integral-volume oxygenated tumor regions and monitored for regrowth. Kaplan–Meier survival analysis was used to assess local tumor control probability (LTCP). The Cox proportional hazards model was used to assess the hazard ratio of tumor progression of Hypoxic Boost vs. Oxygenated Boost for each tumor type controlling for experimental confounding variables such as EPROI radiofrequency, tumor volume, hypoxic fraction, and delay between imaging and radiation treatment.ResultsAn overall significant increase in LTCP from Hypoxia Boost vs. Oxygenated Boost treatments was observed in the full group of three tumor types (p < 0.0001). The effects of tumor volume and hypoxic fraction on LTCP were dependent on tumor type. The delay between imaging and boost treatments did not have a significant effect on LTCP for all tumor types.ConclusionThis study confirms that EPROI locates resistant tumor hypoxic regions for radiation boost, increasing clonogenic LTCP, with potential enhanced therapeutic index in three tumor types. Preclinical absolute EPROI may provide correction for clinical hypoxia images using additional clinical physiologic MRI

The peroxin PEX14 of Neurospora crassa is essential for the biogenesis of both glyoxysomes and Woronin bodies

In the filamentous fungus Neurospora crassa, glyoxysomes and Woronin bodies coexist in the same cell. Because several glyoxysomal matrix proteins and also HEX1, the dominant protein of Woronin bodies, possess typical peroxisomal targeting signals, the question arises as to how protein targeting to these distinct yet related types of microbodies is achieved. Here we analyzed the function of the Neurospora ortholog of PEX14, an essential component of the peroxisomal import machinery. PEX14 interacted with both targeting signal receptors and was localized to glyoxysomes but was virtually absent from Woronin bodies. Nonetheless, a pex14 Delta mutant not only failed to grow on fatty acids because of a defect in glyoxysomal beta-oxidation but also suffered from cytoplasmic bleeding, indicative of a defect in Woronin body-dependent septal pore plugging. Inspection of pex14 Delta mutant hyphae by fluorescence and electron microscopy indeed revealed the absence of Woronin bodies. When these cells were subjected to subcellular fractionation, HEX1 was completely mislocalized to the cytosol. Expression of GFP-HEX1 in wild-type mycelia caused the staining of Woronin bodies and also of glyoxysomes in a targeting signal-dependent manner. Our data support the view that Woronin bodies emerge from glyoxysomes through import of HEX1 and subsequent fission

Spider-Venom Peptides as Bioinsecticides

Over 10,000 arthropod species are currently considered to be pest organisms. They are estimated to contribute to the destruction of ~14% of the world’s annual crop production and transmit many pathogens. Presently, arthropod pests of agricultural and health significance are controlled predominantly through the use of chemical insecticides. Unfortunately, the widespread use of these agrochemicals has resulted in genetic selection pressure that has led to the development of insecticide-resistant arthropods, as well as concerns over human health and the environment. Bioinsecticides represent a new generation of insecticides that utilise organisms or their derivatives (e.g., transgenic plants, recombinant baculoviruses, toxin-fusion proteins and peptidomimetics) and show promise as environmentally-friendly alternatives to conventional agrochemicals. Spider-venom peptides are now being investigated as potential sources of bioinsecticides. With an estimated 100,000 species, spiders are one of the most successful arthropod predators. Their venom has proven to be a rich source of hyperstable insecticidal mini-proteins that cause insect paralysis or lethality through the modulation of ion channels, receptors and enzymes. Many newly characterized insecticidal spider toxins target novel sites in insects. Here we review the structure and pharmacology of these toxins and discuss the potential of this vast peptide library for the discovery of novel bioinsecticides

The significance of peroxisomes in secondary metabolite biosynthesis in filamentous fungi

Peroxisomes are ubiquitous organelles characterized by a protein-rich matrix surrounded by a single membrane. In filamentous fungi, peroxisomes are crucial for the primary metabolism of several unusual carbon sources used for growth (e.g. fatty acids), but increasing evidence is presented that emphasize the crucial role of these organelles in the formation of a variety of secondary metabolites. In filamentous fungi, peroxisomes also play a role in development and differentiation whereas specialized peroxisomes, the Woronin bodies, play a structural role in plugging septal pores. The biogenesis of peroxisomes in filamentous fungi involves the function of conserved PEX genes, as well as genes that are unique for these organisms. Peroxisomes are also subject to autophagic degradation, a process that involves ATG genes. The interplay between organelle biogenesis and degradation may serve a quality control function, thereby allowing a continuous rejuvenation of the organelle population in the cells