Scent‐Mark Identification and Scent‐Marking Behaviour in African Wild Dogs (Lycaon pictus)

Scent‐marking is common in mammals, but where signals are carried by urine and faeces, distinguishing between scent‐marking and mere elimination is problematic. To do so, we documented behaviours and context variables associated with urination and defecation in free‐ranging endangered African wild dogs (Lycaon pictus) and tested whether these were related to the responses of other dogs to deposits. We found that distinct postures were almost uniquely associated with deposits by dominant wild dogs, were more common during urination than defecation, and increased the likelihood that these deposits would be investigated by other wild dogs. The likelihood of investigation depended on the sex and dominance status of the depositor, the type of deposit and the substrate. Urine from dominant females was more likely to be investigated by other wild dogs than any other deposits, and deposits placed on vegetation were more likely to be investigated than those on bare ground. The likelihood that a deposit would be overmarked was affected by the deposit type and the sex and dominance status of the last depositor. Collectively, these results suggest that dominant wild dog urine is of greatest interest to other dogs. Our results show that some deposits by African wild dogs are not scent‐marks and that detailed observations of behaviours and context variables during elimination events can be used to distinguish deposits that are likely to be of communication value.     

Human stick balancing: an intermittent control explanation

There are two issues in balancing a stick pivoting on a finger tip (or mechanically on a moving cart): maintaining the stick angle near to vertical and maintaining the horizontal position within the bounds of reach or cart track. The (linearised) dynamics of the angle are second order (although driven by pivot acceleration), and so, as in human standing, control of the angle is not, by itself very difficult. However, once the angle is under control, the position dynamics are, in general, fourth order. This makes control quite difficult for humans (and even an engineering control system requires careful design). Recently, three of the authors have experimentally demonstrated that humans control the stick angle in a special way: the closed-loop inverted pendulum behaves as a non-inverted pendulum with a virtual pivot somewhere between the stick centre and tip and with increased gravity. Moreover, they suggest that the virtual pivot lies at the radius of gyration (about the mass centre) above the mass centre. This paper gives a continuous-time control-theoretical interpretation of the virtual-pendulum approach. In particular, by using a novel cascade control structure, it is shown that the horizontal control of the virtual pivot becomes a second-order problem which is much easier to solve than the generic fourth-order problem. Hence, the use of the virtual pivot approach allows the control problem to be perceived by the subject as two separate second-order problems rather than a single fourth-order problem, and the control problem is therefore simplified. The theoretical predictions are verified using the data previously presented by three of the authors and analysed using a standard parameter estimation method. The experimental data indicate that although all subjects adopt the virtual pivot approach, the less expert subjects exhibit larger amplitude angular motion and poorly controlled translational motion. It is known that human control systems are delayed and intermittent, and therefore, the continuous-time strategy cannot be correct. However, the model of intermittent control used in this paper is based on the virtual pivot continuous-time control scheme, handles time delays and moreover masquerades as the underlying continuous-time controller. In addition, the event-driven properties of intermittent control can explain experimentally observed variability.     

MuPIT interactive: webserver for mapping variant positions to annotated, interactive 3D structures

Mutation position imaging toolbox (MuPIT) interactive is a browser-based application for single-nucleotide variants (SNVs), which automatically maps the genomic coordinates of SNVs onto the coordinates of available three-dimensional (3D) protein structures. The application is designed for interactive browser-based visualization of the putative functional relevance of SNVs by biologists who are not necessarily experts either in bioinformatics or protein structure. Users may submit batches of several thousand SNVs and review all protein structures that cover the SNVs, including available functional annotations such as binding sites, mutagenesis experiments, and common polymorphisms. Multiple SNVs may be mapped onto each structure, enabling 3D visualization of SNV clusters and their relationship to functionally annotated positions. We illustrate the utility of MuPIT interactive in rationalizing the impact of selected polymorphisms in the PharmGKB database, somatic mutations identified in the Cancer Genome Atlas study of invasive breast carcinomas, and rare variants identified in the exome sequencing project. MuPIT interactive is freely available for non-profit use at http://mupit.icm.jhu.edu.     

Matching roots to their environment

Background

Plants form the base of the terrestrial food chain and provide medicines, fuel, fibre and industrial materials to humans. Vascular land plants rely on their roots to acquire the water and mineral elements necessary for their survival in nature or their yield and nutritional quality in agriculture. Major biogeochemical fluxes of all elements occur through plant roots, and the roots of agricultural crops have a significant role to play in soil sustainability, carbon sequestration, reducing emissions of greenhouse gasses, and in preventing the eutrophication of water bodies associated with the application of mineral fertilizers.

Scope

This article provides the context for a Special Issue of Annals of Botany on ‘Matching Roots to Their Environment’. It first examines how land plants and their roots evolved, describes how the ecology of roots and their rhizospheres contributes to the acquisition of soil resources, and discusses the influence of plant roots on biogeochemical cycles. It then describes the role of roots in overcoming the constraints to crop production imposed by hostile or infertile soils, illustrates root phenotypes that improve the acquisition of mineral elements and water, and discusses high-throughput methods to screen for these traits in the laboratory, glasshouse and field. Finally, it considers whether knowledge of adaptations improving the acquisition of resources in natural environments can be used to develop root systems for sustainable agriculture in the future.     

Hydrodynamic multibead modeling: problems, pitfalls and solutions. 3. Comparison of new approaches for improved predictions of translational properties

Modeling simple and complex biopolymers in solution requires the shapes of these molecules to be approximated by bead modeling procedures, primarily for the prediction of hydrodynamic and scattering quantities. Though several bead modeling strategies (strict, shell and filling models) and a variety of computer programs (preferably the HYDRO suite by the García de la Torre group) are available, several subtle questions remain to be answered, in particular concerning the appropriate volume correction for intrinsic viscosity computations. In this context, various versions of the HYDRO programs and different types of volume corrections, as well as the novel, alternative program ZENO of the Mansfield group, were applied to a plethora of thoroughly designed multibead models of spherical, ellipsoidal, cylindrical and prismatic shapes. A critical comparison of the results obtained reveals a variety of new aspects, useful for many future applications. Among these, application of our recently suggested “reduced volume correction” (RVC) together with specially adapted HYDRO versions and use of ZENO turned out to be highly effective, in particular when aiming at filling model strategies and using high bead numbers, a domain not fully supported by the recent HYDRO++ versions. By our approaches, the values of translational properties (diffusion coefficients, D, and intrinsic viscosities, [η]) of all multibead models applied were anticipated correctly.     

The barley MATE gene,HvAACT1, increases citrate efflux and Al3+ tolerance when expressed in wheat and barley

Background and Aims

Aluminium is toxic in acid soils because the soluble Al³⁺ inhibits root growth. A mechanism of Al³⁺ tolerance discovered in many plant species involves the release of organic anions from root apices. The Al³⁺-activated release of citrate from the root apices of Al³⁺-tolerant genotypes of barley is controlled by a MATE gene named HvAACT1 that encodes a citrate transport protein located on the plasma membrane. The aim of this study was to investigate whether expressing HvAACT1 with a constitutive promoter in barley and wheat can increase citrate efflux and Al³⁺ tolerance of these important cereal species.

Methods HvAACT1

was over-expressed in wheat (Triticum aestivum) and barley (Hordeum vulgare) using the maize ubiquitin promoter. Root apices of transgenic and control lines were analysed for HvAACT1 expression and organic acid efflux. The Al³⁺ tolerance of transgenic and control lines was assessed in both hydroponic solution and acid soil.

Key Results and Conclusions

Increased HvAACT1 expression in both cereal species was associated with increased citrate efflux from root apices and enhanced Al³⁺ tolerance, thus demonstrating that biotechnology can complement traditional breeding practices to increase the Al³⁺ tolerance of important crop plants.     

Cardiomyocyte-specific perilipin 5 overexpression leads to myocardial steatosis and modest cardiac dysfunction

Presence of ectopic lipid droplets (LDs) in cardiac muscle is associated to lipotoxicity and tissue dysfunction. However, presence of LDs in heart is also observed in physiological conditions, such as when cellular energy needs and energy production from mitochondria fatty acid β-oxidation are high (fasting). This suggests that development of tissue lipotoxicity and dysfunction is not simply due to the presence of LDs in cardiac muscle but due at least in part to alterations in LD function. To examine the function of cardiac LDs, we obtained transgenic mice with heart-specific perilipin 5 (Plin5) overexpression (MHC-Plin5), a member of the perilipin protein family. Hearts from MHC-Plin5 mice expressed at least 4-fold higher levels of plin5 and exhibited a 3.5-fold increase in triglyceride content versus nontransgenic littermates. Chronic cardiac excess of LDs was found to result in mild heart dysfunction with decreased expression of peroxisome proliferator-activated receptor (PPAR)α target genes, decreased mitochondria function, and left ventricular concentric hypertrophia. Lack of more severe heart function complications may have been prevented by a strong increased expression of oxidative-induced genes via NF-E2-related factor 2 antioxidative pathway. Perilipin 5 regulates the formation and stabilization of cardiac LDs, and it promotes cardiac steatosis without major heart function impairment.