Structural Geology and Finite Strain Analysis of the Precambrian Thunderhead Sandstone Along the Greenbrier Fault and the Roundtop Klippe: Great Smoky Mountains, Tennessee

The Precambrian Thunderhead Sandstone, along the Greenbrier Fault and the Roundtop Klippe, records strain from two distinct episodes of deformation. The first strains are generally related to the emplacement of the Greenbrier Fault. These strains are probably due to simple shear along the base of the fault, and appear similar to the strain fabrics within in the Cades Sandstone to the southwest. This strain fabric is characterized by principle strain axes which lie subparallel to the orientation of the Greenbrier Fault. These strains were later effected by strains related to the emplacement of the Sinks Fault, a high angle thrust which displaced the Greenbrier Thrust Sheet. This fabric is probably also the result of simple shear on the Sinks and is similarly characterized by the subparallelism of the principal extension axes and the Sinks Fault plane. Finite strains were calculated for 17 samples of Thunderhead Sandstone, using the Rf/o and Fry methods. Twelve samples show that uniaxial extension is dominant over flattening within the Thunderhead. In five samples flattening is dominant over uniaxial extension. The Greenbrier main sheet shows less strain in the same orientations than that seen in the Roundtop Klippe. King (1964, 1968) shows two interpretations of the area, one with the Sinks as a folded part of the Greenbrier and one with the Sinks as a later fault. Superposed strain patterns suggest that both are correct

Monodisperse self-assembly in a model with protein-like interactions

We study the self-assembly behaviour of patchy particles with `protein-like' interactions that can be considered as a minimal model for the assembly of viral capsids and other shell-like protein complexes. We thoroughly explore the thermodynamics and dynamics of self assembly as a function of the parameters of the model and find robust assembly of all target structures considered. Optimal assembly occurs in the region of parameter space where a free energy barrier regulates the rate of nucleation, thus preventing the premature exhaustion of the supply of monomers that can lead to the formation of incomplete shells. The interactions also need to be specific enough to prevent the assembly of malformed shells, but whilst maintaining kinetic accessibility. Free-energy landscapes computed for our model have a funnel-like topography guiding the system to form the target structure, and show that the torsional component of the interparticle interactions prevents the formation of disordered aggregates that would otherwise act as kinetic traps.Comment: 11 pages; 10 figure

Prophylactic zoledronic acid therapy to prevent or modify Paget’s disease of bone progression in adults with SQSTM1 mutations: the ZiPP RCT

Background:Paget’s disease of bone is characterised by focal abnormalities of bone turnover resulting in various complications. It often presents at an advanced stage with irreversible bone damage. At this point, the symptomatic benefits of treatment are blunted. Paget’s disease of bone has a strong genetic component and the most important susceptibility gene is SQSTM1. Carriers of SQSTM1 mutations have more severe disease with an earlier age of onset than non-carriers and about 80% develop Paget’s disease of bone by the seventh decade.Objectives:The primary objective was to determine if zoledronic acid could prevent new Paget’s disease of bone-like bone lesions in SQSTM1 mutation carriers. Secondary objectives were to assess if zoledronic acid could: modify existing Paget’s disease of bone lesions, markers of bone turnover, quality of life, bone pain, anxiety, depression or the risk of complications.Design:This was a multicentre, double-blind placebo-controlled trial. Genetic screening of the SQSTM1 gene was offered to people with a family history of Paget’s disease of bone, identifying 222 mutation carriers who consented to participate. At baseline, a radionuclide bone scan was performed; biochemical markers of bone turnover were measured and questionnaires on pain, quality of life and mental health were completed. Participants completed annual biochemical markers measurements and questionnaires. Adverse events were recorded on a continuous basis. At the end of study, the bone scan was repeated, along with biochemical markers and questionnaires.Setting:This was a multicentre trial that was conducted at 27 secondary care referral centres for bone disease in 7 countries. All the visits were conducted within a secondary healthcare setting.Participants Interventions:Participants were randomly allocated to receive a single infusion of the bisphosphonate zoledronic acid 5 mg or an identical placebo.Main outcome measures:The study’s primary outcome measure was defined as the total number of participants who developed new bone lesions on radionuclide bone scans with the characteristics of PDB between the baseline visit and the final end-of-study visit. The secondary outcomes included the number of new PDB bone lesions on radionuclide bone scans, change in the activity of existing PDB bone lesions at the end of study assessed by radionuclide scans; changes in plasma type I collagen C-telopeptides (CTX); plasma procollagen type I amino-terminal propeptide (PINP); serum bone-specific alkaline phosphatase (BAP); quality of life assessed by SF-36, BPI, HADS questionnaires; the presence and severity of localized bone pain assessed by the BPI pain manikin; and the development of PDB-related skeletal events (PDRSE) in SQSTM1 mutation carriers including new lesions, complications (fractures, deformity), or the need for treatment of PDB.Methods:This was a multicentre, double-blind placebo-controlled trial. Genetic screening of the SQSTM1 gene was offered to people with a family history of Paget’s disease of bone, identifying 222 mutation carriers who consented to participate. At baseline, a radionuclide bone scan was performed; biochemical markers of bone turnover were measured and questionnaires on pain, quality of life and mental health were completed. Participants were randomly allocated to receive a single infusion of the bisphosphonate zoledronic acid 5 mg or an identical placebo. Participants completed annual biochemical markers measurements and questionnaires. Adverse events were recorded on a continuous basis. At the end of study, the bone scan was repeated, along with biochemical markers and questionnaires.Results:At baseline, 21/222 individuals (9.5%) had evidence of Paget’s disease of bone on bone scans. In the placebo group, 2/90 individuals (2.2%) developed new bone lesions compared with 0/90 (0%) in the zoledronic acid group (odds ratio 0.41, 95% confidence interval 0.00 to 3.43; p = 0.25). Eight participants in the placebo group had a poor outcome (new/unchanged/progressing lesions) compared with none in the zoledronic acid group (odds ratio 0.08, 95% confidence interval 0.00 to 0.42; p = 0.003). With placebo, 1/29 (3.4%) lesions disappeared compared with 13/15 (86.6%) with zoledronic acid (p &lt; 0.0001). One participant allocated to placebo required treatment with zoledronic acid due to a complication of Paget’s disease of bone. Significant reductions were observed for serum C-terminal telopeptide (p &lt; 0.0001), bone-specific alkaline phosphatase (p = 0.0003) and N-terminal propeptide of type I procollagen (p &lt; 0.0001) in the zoledronic acid group compared with placebo. There was no significant difference between groups in quality of life, pain, anxiety or depression.Conclusion:Genetic testing for SQSTM1 mutations coupled with bone scan examination can detect early Paget’s disease of bone in those with a family history of the disorder and zoledronic acid treatment can favourably modify its evolution.The study had some limitations. First, 9.5% of participants already had Paget’s disease of bone, reducing power. Second, only two participants developed new lesions compared to the 15% expected. The small number of events meant the study was underpowered for the primary outcome and we were unable to adjust analyses for co-variates or family clustering.An extended follow-up in the zoledronic acid in the prevention of Paget’s disease – long-term extension study is in progress and will provide valuable information on the duration of effects of a single zoledronic acid infusion. It will be important to consider a health economic analysis to model the effects of genetic testing, scanning and zoledronic acid treatment, to evaluate long-term clinical and symptomatic benefits.<br/

Oakleaf: an S locus-linked mutation of Primula vulgaris that affects leaf and flower development

•In Primula vulgaris outcrossing is promoted through reciprocal herkogamy with insect-mediated cross-pollination between pin and thrum form flowers. Development of heteromorphic flowers is coordinated by genes at the S locus. To underpin construction of a genetic map facilitating isolation of these S locus genes, we have characterised Oakleaf, a novel S locus-linked mutant phenotype. •We combine phenotypic observation of flower and leaf development, with classical genetic analysis and next-generation sequencing to address the molecular basis of Oakleaf. •Oakleaf is a dominant mutation that affects both leaf and flower development; plants produce distinctive lobed leaves, with occasional ectopic meristems on the veins. This phenotype is reminiscent of overexpression of Class I KNOX-homeodomain transcription factors. We describe the structure and expression of all eight P. vulgaris PvKNOX genes in both wild-type and Oakleaf plants, and present comparative transcriptome analysis of leaves and flowers from Oakleaf and wild-type plants. •Oakleaf provides a new phenotypic marker for genetic analysis of the Primula S locus. We show that none of the Class I PvKNOX genes are strongly upregulated in Oakleaf leaves and flowers, and identify cohorts of 507 upregulated and 314 downregulated genes in the Oakleaf mutant

The self-assembly and evolution of homomeric protein complexes

We introduce a simple "patchy particle" model to study the thermodynamics and dynamics of self-assembly of homomeric protein complexes. Our calculations allow us to rationalize recent results for dihedral complexes. Namely, why evolution of such complexes naturally takes the system into a region of interaction space where (i) the evolutionarily newer interactions are weaker, (ii) subcomplexes involving the stronger interactions are observed to be thermodynamically stable on destabilization of the protein-protein interactions and (iii) the self-assembly dynamics are hierarchical with these same subcomplexes acting as kinetic intermediates.Comment: 4 pages, 4 figure

Nerve Agent Hydrolysis Activity Designed into a Human Drug Metabolism Enzyme

Organophosphorus (OP) nerve agents are potent suicide inhibitors of the essential neurotransmitter-regulating enzyme acetylcholinesterase. Due to their acute toxicity, there is significant interest in developing effective countermeasures to OP poisoning. Here we impart nerve agent hydrolysis activity into the human drug metabolism enzyme carboxylesterase 1. Using crystal structures of the target enzyme in complex with nerve agent as a guide, a pair of histidine and glutamic acid residues were designed proximal to the enzyme's native catalytic triad. The resultant variant protein demonstrated significantly increased rates of reactivation following exposure to sarin, soman, and cyclosarin. Importantly, the addition of these residues did not alter the high affinity binding of nerve agents to this protein. Thus, using two amino acid substitutions, a novel enzyme was created that efficiently converted a group of hemisubstrates, compounds that can start but not complete a reaction cycle, into bona fide substrates. Such approaches may lead to novel countermeasures for nerve agent poisoning

Thyroid hormone regulates distinct paths to maturation in pigment cell lineages

Thyroid hormone (TH) regulates diverse developmental events and can drive disparate cellular outcomes. In zebrafish, TH has opposite effects on neural crest derived pigment cells of the adult stripe pattern, limiting melanophore population expansion, yet increasing yellow/orange xanthophore numbers. To learn how TH elicits seemingly opposite responses in cells having a common embryological origin, we analyzed individual transcriptomes from thousands of neural crest-derived cells, reconstructed developmental trajectories, identified pigment cell-lineage specific responses to TH, and assessed roles for TH receptors. We show that TH promotes maturation of both cell types but in distinct ways. In melanophores, TH drives terminal differentiation, limiting final cell numbers. In xanthophores, TH promotes accumulation of orange carotenoids, making the cells visible. TH receptors act primarily to repress these programs when TH is limiting. Our findings show how a single endocrine factor integrates very different cellular activities during the generation of adult form