Asteropeia and Physena (Caryophyllales): A case study in comparative wood anatomy

Previous analyses ofAsteropeia andPhysena have not compared the wood anatomy of these genera to those of Caryophyllales s.l. Molecular evidence shows that the two genera from a clade that is a sister group of the core Caryophyllales. Synapomorphies of theAsteropeia-Physena clade include small circular alternate pits on vessels, presence of vasicentric tracheids plus fiber-tracheids, presence of abaxial-confluent plus diffuse axial parenchyma, and presence of predominantly uniseriate rays. These features are analyzed with respect to habit and ecology of the two genera. Solitary vessels, present in both genera, are related to the presence of vasicentric tracheids. Autapomorphies in the two genera seem related to adaptations byPhysena as a shrub of moderately dry habitats (e.g., narrower vessel elements, abundant vasicentric tracheids, square to erect cells in rays) as compared to alternate character expressions that seem related to the arboreal habit and humid forest ecology ofAsteropeia. The functional significance of vasicentric tracheids and fiber-tracheids in dicotyledons is briefly reviewed in the light of wood anatomy of the two genera.     

Long-Range Effects of Familial Hypertrophic Cardiomyopathy Mutations E180G and D175N on the Properties of Tropomyosin

Cardiac α-tropomyosin (Tm) single-site mutations D175N and E180G cause familial hypertrophic cardiomyopathy (FHC). Previous studies have shown that these mutations increase both Ca(2+) sensitivity and residual contractile activity at low Ca(2+) concentrations, which causes incomplete relaxation during diastole resulting in hypertrophy and sarcomeric disarray. However, the molecular basis for the cause and the difference in the severity of the manifested phenotypes of disease are not known. In this work we have (1) used ATPase studies using reconstituted thin filaments in solution to show that these FHC mutants result in an increase in Ca(2+) sensitivity and an increased residual level of ATPase, (2) shown that both FHC mutants increase the rate of cleavage at R133, ～45 residues N-terminal to the mutations, when free and bound to actin, (3) shown that for Tm-E180G, the increase in the rate of cleavage is greater than that for D175N, and (4) shown that for E180G, cleavage also occurs at a new site 53 residues C-terminal to E180G, in parallel with cleavage at R133. The long-range decreases in dynamic stability due to these two single-site mutations suggest increases in flexibility that may weaken the ability of Tm to inhibit activity at low Ca(2+) concentrations for D175N and to a greater degree for E180G, which may contribute to differences in the severity of FHC.     

A theoretical study of polymorphism in VQIVYK fibrils

The VQIVYK fragment from the Tau protein, also known as PHF6, is essential for aggregation of Tau into neurofibrillary lesions associated with neurodegenerative diseases. VQIVYK itself forms amyloid fibrils composed of paired β-sheets. Therefore, the full Tau protein and VQIVYK fibrils have been intensively investigated. A central issue in these studies is polymorphism, the ability of a protein to fold into more than one structure. Using all-atom molecular simulations, we generate five stable polymorphs of VQIVYK fibrils, establish their relative free energy with umbrella sampling methods, and identify the side chain interactions that provide stability. The two most stable polymorphs, which have nearly equal free energy, are formed by interdigitation of the mostly hydrophobic VIY “face” sides of the β-sheets. Another stable polymorph is formed by interdigitation of the QVK “back” sides. When we turn to examine structures from cryo-electron microscopy experiments on Tau filaments taken from diseased patients or generated in vitro, we find that the pattern of side chain interactions found in the two most stable face-to-face as well as the back-to-back polymorphs are recapitulated in amyloid structures of the full protein. Thus, our studies suggest that the interactions stabilizing PHF6 fibrils explain the amyloidogenicity of the VQIVYK motif within the full Tau protein and provide justification for the use of VQIVYK fibrils as a test bed for the design of molecules that identify or inhibit amyloid structures.     

A Case Study: Fecal Corticosteroid and Behavior as Indicators of Welfare During Relocation of an Asian Elephant

This study was a preliminary investigation of an enzyme immunoassay for measuring fecal glucocorticoid metabolites in a male Asian elephant (Elephas maximus) by investigating changes in behavior and cortisol metabolite excretion associated with a putative stressful event. The study collected fecal samples for 10 days prior to, and 10 days after, 24-hr transport and relocation of the elephant to a new herd. The study measured cortisol metabolites using 2 enzyme immunoassays indicating a 389% and 340% increase in cortisol metabolite excretion following relocation. Maximal cortisol metabolite excretion occurred 2 days after relocation and remained elevated during establishment of the new herd. Stereotypic behavior increased approximately 400% after relocation. The relocation disturbed sleep patterns, the elephant spent less time sleeping during the night, and the elephant slept standing up. These results provide preliminary evidence that noninvasive monitoring of fecal cortisol metabolites can be used to investigate adrenal activity in Asian elephants and may be a safe, practical, and accurate welfare indicator.     

Theoretical models for coronary vascular biomechanics: progress & challenges

A key aim of the cardiac Physiome Project is to develop theoretical models to simulate the functional behaviour of the heart under physiological and pathophysiological conditions. Heart function is critically dependent on the delivery of an adequate blood supply to the myocardium via the coronary vasculature. Key to this critical function of the coronary vasculature is system dynamics that emerge via the interactions of the numerous constituent components at a range of spatial and temporal scales. Here, we focus on several components for which theoretical approaches can be applied, including vascular structure and mechanics, blood flow and mass transport, flow regulation, angiogenesis and vascular remodelling, and vascular cellular mechanics. For each component, we summarise the current state of the art in model development, and discuss areas requiring further research. We highlight the major challenges associated with integrating the component models to develop a computational tool that can ultimately be used to simulate the responses of the coronary vascular system to changing demands and to diseases and therapies.     

Shared antigenicity between the polar filaments of myxosporeans and other Cnidaria

Nematocysts containing coiled polar filaments are a distinguishing feature of members of the phylum Cnidaria. As a first step to characterizing the molecular structure of polar filaments, a polyclonal antiserum was raised in rabbits against a cyanogen bromide-resistant protein extract of mature cysts containing spores of Myxobolus pendula. The antiserum reacted only with proteins associated with extruded polar filaments. Western blot and whole-mount immunohistochemical analyses indicated a conservation of polar filament epitopes between M. pendula and 2 related cnidarians, i.e., the anthozoan, Nematostella vectensis, and the hydrozoan, Hydra vulgaris. This conservation of polar filament epitopes lends further support to a shared affinity between Myxozoa and cnidarians.     

Mitochondrial DNA offers unique insights into invasion history of the common starling

Mitochondrial DNA (mtDNA) can be a powerful genetic marker for tracing origins and history of invasive populations. Here, we use mtDNA to address questions relevant to the understanding of invasion pathways of common starlings (Sturnus vulgaris) into Western Australia (WA) and discuss the utility of this marker to provide information useful to invasive species management. Mitochondrial sequence data indicate two geographically restricted genetic groups within Australia. Evidence of dispersal from genetically distinct sources outside the sampled range of starlings in Australia suggests increased vigilance by management agencies may be required to prevent further incursions from widely separated localities. Overall, genetic diversity in Australia was lower than in samples from the native range. Within Australia, genetic diversity was lowest in the most recently colonized area in the west, indicating that demographic bottlenecks have occurred in this area. Evidence of restricted dispersal between localities on the edge of the range expansion (ERE) in WA and other Australian sampling localities suggests that localized control within the ERE may be effective in preventing further range expansion. Signatures of spatial and demographic expansion are present in mismatch analyses from sampling localities located at the ERE, but neutrality indices did not support this finding, suggesting that the former may be more sensitive to recent expansion. Additionally, mismatch analyses support the presence of admixture, which is likely to have occurred pre-introduction. We compare our findings with those from a microsatellite study of the same samples and discuss how the mtDNA analyses used here offer valuable and unique insights into the invasion history of introduced species.