Structure and Nucleotide Polymorphisms in Pig Uncoupling Protein 2 and 3 Genes

Uncoupling proteins (UCPs) are mitochondrial membrane transporters, acting as an uncoupler in oxidative phosphorylation. In this study, we designed 11 primer sets based on the human and mouse UCP2, UCP3 sequences and successfully amplified full regions of porcine UCP2 and UCP3 by polymerase chain reactions (PCR). Comparison of the UCP2 and UCP3 genic structures revealed a highly conservative region was putatively presented, showing the second transmembrane domain may be the UCPs' cardinal function region. Altogether 23 nucleotide polymorphisms of UCP2 and UCP3 genes were discovered in Yorkshire, Wuzhishan, and Lepinghua pigs. These polymorphisms included 3 missense mutations, 16 intronic substitutions, and 4 intronic deletions. The substitution of Ala-55-Val in UCP2 is actually the most common mutation in human. We also calculated genotypic frequencies of five polymorphisms in three pig breeds.     

Direct numerical simulation of a 2D-stented aortic heart valve at physiological flow rates

We study the nonlinear interaction of an aortic heart valve, composed of hyperelastic corrugated leaflets of finite density attached to a stented vessel under physiological flow conditions. In our numerical simulations, we use a 2D idealised representation of this arrangement. Blood flow is caused by a time-varying pressure gradient that mimics that of the aortic valve and corresponds to a peak Reynolds number equal to 4050. Here, we fully account for the shear-thinning behaviour of the blood and large deformations and contact between the leaflets by solving the momentum and mass balances for blood and leaflets. The mixed finite element/Galerkin method along with linear discontinuous Lagrange multipliers for coupling the fluid and elastic domains is adopted. Moreover, a series of challenging numerical issues such as the finite length of the computational domain and the conditions that should be imposed on its inflow/outflow boundaries, the accurate time integration of the parabolic and hyperbolic momentum equations, the contact between the leaflets and the non-conforming mesh refinement in part of the domain are successfully resolved. Calculations for the velocity and the shear stress fields of the blood reveal that boundary layers appear on both sides of a leaflet. The one along the ventricular side transfers blood with high momentum from the core region of the vessel to the annulus or the sinusoidal expansion, causing the continuous development of flow instabilities. At peak systole, vortices are convected in the flow direction along the annulus of the vessel, whereas during the closure stage of the valve, an extremely large vortex develops in each half of the flow domain.     

New head models extracted from thermal infrared (IR) images for dosimetry computations

In electromagnetic dosimetry, anatomical human models are commonly obtained by segmentation of magnetic resonance imaging or computed tomography scans. In this paper, a human head model extracted from thermal infrared images is examined in terms of its applicability to specific absorption rate (SAR) calculations. Since thermal scans are two-dimensional (2D) representation of surface temperature, this allows researchers to overcome the extensive computational demand associated with 3D simulation. The numerical calculations are performed using the finite-difference time-domain method with mesh sizes of 2 mm at 900 MHz plane wave irradiation. The power density of the incident plane wave is assumed to be 10 W/m². Computations were compared with a realistic anatomical head model. The results show that although there were marked differences in the local SAR distribution in the various tissues in the two models, the 1 g peak SAR values are approximately similar in the two models.     

The Synthesis and Biology of Fluorinated Prostacyclins

Abstract

Clostridium thermocellum produces a highly active cellulase system that consists of a high-M_r multienzyme complex termed cellulosome. Hydrolytic components of the cellulosome are organized around a large, noncatalytic glycoprotein termed CipA that acts both as a scaffolding component and a cellulose-binding factor. Catalytic subunits of the cellulosome bear conserved, noncatalytic subdomains, termed dockerin domains, which bind to receptor domains of CipA, termed cohesin domains. CipA includes nine cohesin domains, a cellulose-binding domain, and a specialized dockerin domain. Proteins of the cell envelope carrying cohesin domains that specifically bind the dockerin domain of CipA have been identified. These proteins may mediate anchoring of the cellulosomes to the cell surface. Cellulase complexes similar to the cellulosome of C. thermocellum are produced by several cellulolytic clostridia. High-Mr multienzyme complexes have also been identified in anaerobic rumen fungi. The architecture of the fungal complexes also seems to rely on the interaction of conserved, noncatalytic docking domains with a scaffolding component. However, the sequence of the fungal docking domains bears no resemblance to the clostridial dockerin domains, suggesting that the fungal and clostridial complexes arose independently.     

Structural coupling of the EF hand and C‐terminal GTPase domains in the mitochondrial protein Miro

Miro is a highly conserved calcium‐binding GTPase at the regulatory nexus of mitochondrial transport and autophagy. Here we present crystal structures comprising the tandem EF hand and carboxy terminal GTPase (cGTPase) domains of Drosophila Miro. The structures reveal two previously unidentified ‘hidden’ EF hands, each paired with a canonical EF hand. Each EF hand pair is bound to a helix that structurally mimics an EF hand ligand. A key nucleotide‐sensing element and a Pink1 phosphorylation site both lie within an extensive EF hand–cGTPase interface. Our results indicate structural mechanisms for calcium, nucleotide and phosphorylation‐dependent regulation of mitochondrial function by Miro.     

Rab35: GEFs,GAPs and Effectors

Rabs are the largest family of small GTPases and are master regulators of membrane trafficking. Following activation by guanine‐nucleotide exchange factors (GEFs), each Rab binds a specific set of effector proteins that mediate the various downstream functions of that Rab. Then, with the help of GTPase‐activating proteins, the Rab converts GTP to GDP, terminating its function. There are over 60 Rabs in humans and only a subset has been analyzed in any detail. Recently, Rab35 has emerged as a key regulator of cargo recycling at endosomes, with an additional role in regulation of the actin cytoskeleton. Here, we will focus on the regulation of Rab35 activity by the connecdenn/DENND1 family of GEFs and the TBC1D10/EPI64 family of GTPase‐activating proteins. We will describe how analysis of these proteins, as well as a plethora of Rab35 effectors has provided insights into Rab35 function. Finally, we will describe how Rab35 provides a novel link between the Rab and Arf family of GTPases with implications for tumor formation and invasiveness .      

Integrating frugivory and animal movement: a review of the evidence and implications for scaling seed dispersal

General principles about the consequences of seed dispersal by animals for the structure and dynamics of plant populations and communities remain elusive. This is in part because seed deposition patterns emerge from interactions between frugivore behaviour and the distribution of food resources, both of which can vary over space and time. Here we advocate a frugivore‐centred, process‐based, synthetic approach to seed dispersal research that integrates seed dispersal ecology and animal movement across multiple spatio‐temporal scales. To guide this synthesis, we survey existing literature using paradigms from seed dispersal and animal movement. Specifically, studies are discussed with respect to five criteria: selection of focal organisms (animal or plant); measurement of animal movement; characterization of seed shadow; animal, plant and environmental factors included in the study; and scales of the study. Most studies focused on either frugivores or plants and characterized seed shadows directly by combining gut retention time with animal movement data or indirectly by conducting maternity analysis of seeds. Although organismal traits and environmental factors were often measured, they were seldom used to characterize seed shadows. Multi‐scale analyses were rare, with seed shadows mostly characterized at fine spatial scales, over single fruiting seasons, and for individual dispersers. Novel animal‐ and seed‐tracking technologies, remote environmental monitoring tools, and advances in analytical methods can enable effective implementation of a hierarchical mechanistic approach to the study of seed dispersal. This kind of mechanistic approach will provide novel insights regarding the complex interplay between the factors that modulate animal behaviour and subsequently influence seed dispersal patterns across spatial and temporal scales.     

Endogenous electromagnetic fields in plant leaves: a new hypothesis for vascular pattern formation

Electromagnetic (EM) phenomena have long been implicated in biological development, but few detailed, practical mechanisms have been put forth to connect electromagnetism with morphogenetic processes. This work describes a new hypothesis for plant leaf veination, whereby an endogenous electric field forming as a result of a coherent Frohlich process, and corresponding to an EM resonant mode of the developing leaf structure, is capable of instigating leaf vascularisation. In order to test the feasibility of this hypothesis, a three-dimensional, EM finite-element model (FEM) of a leaf primordium was constructed to determine if suitable resonant modes were physically possible for geometric and physical parameters similar to those of developing leaf tissue. Using the FEM model, resonant EM modes with patterns of relevance to developing leaf vein modalities were detected. On account of the existence of shared geometric signatures in a leaf's vascular pattern and the electric field component of EM resonant modes supported by a developing leaf structure, further theoretical and experimental investigations are warranted. Significantly, this hypothesis is not limited to leaf vascular patterning, but may be applicable to a variety of morphogenetic phenomena in a number of living systems.