The sequence and structure of snake gourd (Trichosanthes anguina) seed lectin, a three-chain nontoxic homologue of type II RIPs

The sequence and structure of snake gourd seed lectin (SGSL), a nontoxic homologue of type II ribosome-inactivating proteins (RIPs), have been determined by mass spectrometry and X-ray crystallography, respectively. As in type II RIPs, the molecule consists of a lectin chain made up of two beta-trefoil domains. The catalytic chain, which is connected through a disulfide bridge to the lectin chain in type II RIPs, is cleaved into two in SGSL. However, the integrity of the three-dimensional structure of the catalytic component of the molecule is preserved. This is the first time that a three-chain RIP or RIP homologue has been observed. A thorough examination of the sequence and structure of the protein and of its interactions with the bound methyl-alpha-galactose indicate that the nontoxicity of SGSL results from a combination of changes in the catalytic and the carbohydrate-binding sites. Detailed analyses of the sequences of type II RIPs of known structure and their homologues with unknown structure provide valuable insights into the evolution of this class of proteins. They also indicate some variability in carbohydrate-binding sites, which appears to contribute to the different levels of toxicity exhibited by lectins from various sources.

Waiting for Gajah: an elephant mutualist's contingency plan for an endangered megafaunal disperser

Large animals are disproportionately likely to go extinct, and the effects of this on ecosystem processes are unclear. Megaherbivores (weighing over 1000kg) are thought to be particularly effective seed dispersers, yet only a few plant species solely or predominantly adapted for dispersal by megaherbivores have been identified. The reasons for this paradox may be elucidated by examining the ecology of so-called megafaunal fruiting species in Asia, where large-fruited species have been only sparsely researched. We conducted focal tree watches, camera trapping, fruit ageing trials, dung seed counts and germination trials to understand the ecology of Dillenia indica, a large-fruited species thought to be elephant-dispersed, in a tropical moist forest (Buxa Tiger Reserve, India). We find that the initial hardness of the fruit of D.indica ensures that its small (6mm) seeds will primarily be consumed and dispersed by elephants and perhaps other megaherbivores. Elephants removed 63.3% of camera trap-monitored fruits taken by frugivores. If the fruit of D.indica is not removed by a large animal, the seeds of D.indica become available to successively smaller frugivores as its fruits soften. Seeds from both hard and soft fruits are able to germinate, meaning these smaller frugivores may provide a mechanism for dispersal without megaherbivores.Synthesis. Dillenia indica's strategy for dispersal allows it to realize the benefits of dispersal by megaherbivores without becoming fully reliant on these less abundant species. This risk-spreading dispersal behaviour suggests D.indica will be able to persist even if its megafaunal disperser becomes extinct.

Examining the Effectiveness of Discriminant Function Analysis and Cluster Analysis in Species Identification of Male Field Crickets Based on Their Calling Songs

Traditional taxonomy based on morphology has often failed in accurate species identification owing to the occurrence of cryptic species, which are reproductively isolated but morphologically identical. Molecular data have thus been used to complement morphology in species identification. The sexual advertisement calls in several groups of acoustically communicating animals are species-specific and can thus complement molecular data as non-invasive tools for identification. Several statistical tools and automated identifier algorithms have been used to investigate the efficiency of acoustic signals in species identification. Despite a plethora of such methods, there is a general lack of knowledge regarding the appropriate usage of these methods in specific taxa. In this study, we investigated the performance of two commonly used statistical methods, discriminant function analysis (DFA) and cluster analysis, in identification and classification based on acoustic signals of field cricket species belonging to the subfamily Gryllinae. Using a comparative approach we evaluated the optimal number of species and calling song characteristics for both the methods that lead to most accurate classification and identification. The accuracy of classification using DFA was high and was not affected by the number of taxa used. However, a constraint in using discriminant function analysis is the need for a priori classification of songs. Accuracy of classification using cluster analysis, which does not require a priori knowledge, was maximum for 6-7 taxa and decreased significantly when more than ten taxa were analysed together. We also investigated the efficacy of two novel derived acoustic features in improving the accuracy of identification. Our results show that DFA is a reliable statistical tool for species identification using acoustic signals. Our results also show that cluster analysis of acoustic signals in crickets works effectively for species classification and identification.

Mahogany seed - a step forward in deciphering autorotation

This article presents an experimental approach for evaluating the various flight characteristics of a mahogany seed in its autorotative descent. Analytical formulae proposed by Yasuda and Azuma are used to interpret the results. The findings are used in the development of a sophisticated blade element computational model, primarily to analyse planar autorotating systems. This approximate computational approach is then used to predict the flight performance of mahogany seeds and the results are compared with experimental data. The potential use of the computational model in the design of autorotating systems is then brought to light.

Influence of seed layer orientation on the growth and physical properties of SnS nanostructures

Stoichiometric tin (II) sulfide (SnS) nano-structures were synthesized on SnS(010)/glass substrates using a simple and low-temperature chemical solution method, and their physical properties were investigated. The as-synthesized SnS nanostructures exhibited orthorhombic crystal structure and most of the nanocrystals are preferentially oriented along the <010> direction. These nanostructures showed p-type electrical conductivity and high electrical resistivity of 93 Omega cm. SnS nanostructures exhibited a direct optical band gap of 1.43 eV. While increasing the surrounding temperature from 20 to 150 degrees C, the electrical resistivity of the structures decreased and exhibited the activation energy of 0.28 eV.

Parasites exert conflicting selection pressures to affect reproductive asynchrony of their host plant in an obligate pollination mutualism

1. Plant reproductive phenology is generally viewed as an individual's strategy to maximize gamete exchange and propagule dispersal and is often considered largely dependent on patterns of floral initiation. Reproductive phenology, however, can be affected by proximate responses to pollinators, parasites and herbivores which could influence floral longevity or fruit development time. 2. We examined the influence of insect interactants on within-plant reproductive phenology in the fig-fig wasp nursery pollination mutualism in Ficus racemosa (Moraceae). Most figs support a wasp community comprised of a mutualistic pollinator, with several host-plant-specific non-pollinating herbivorous gallers and parasitoids. These wasps reproduce within enclosed inflorescences called syconia, which develop into fruit after pollination. While different wasp species oviposit into syconia at varying times during its ontogeny, all wasp progeny are constrained to exit syconia simultaneously just prior to fruit ripening. Developing larvae of early-ovipositing wasps may hasten syconium ontogeny through formation of earlier and larger nutrient sinks, whereas larvae of late-arriving parasites may lengthen syconium ontogeny to complete their development successfully. Seeds are also important nutrient sinks. The number of seeds and the type and number of developing wasps may therefore be expected to influence syconium development times, thereby affecting the reproductive synchrony of syconia on a plant. 3. Observations on naturally pollinated and parasitized syconia indicated that their seed and wasp content affected syconium development time. Experimental manipulations of syconia to produce only seeds or various combinations of wasps confirmed this finding. Early-ovipositing galler progeny reduced syconium development times, while gallers ovipositing concurrently with pollinators had no effect on syconium development. Late-ovipositing parasitoid progeny, the presence of only seeds within the syconium, or delayed pollination increased syconium development time. The differential development of syconia, which was influenced by mutualistic or parasitic progeny, accordingly contributed to within-tree reproductive asynchrony. 4. Synthesis. Individual reproductive units in fig trees called syconia, which also function as brood sites for pollinating and parasitic fig wasps, have plastic development durations dependent on pollination timing and species of wasps developing within them. Syconium development times are a likely compromise between conflicting demands from developing seeds and different wasp species.

A Kunitz-type serine protease inhibitor from Butea monosperma seed and its influence on developmental physiology of Helicoverpa armigera

A protease inhibitor from the seeds of Butea monosperma (BmPI) was purified, characterized and studied for its influence on developmental physiology of Helicover-pa armigera. BmPI on two-dimensional separations indicated the presence of a 14 kDa protein with an isoelectric point in the acidic region (pl 5.6). Multiple Sequence Analysis data suggested that the BmPI contains a sequence motif which is conserved in various trypsin and chymotrypsin inhibitors of Kunitz-type. The inhibitor exhibited trypsin inhibitory activity in a broad range of pH (4-10) and temperature (10-80 degrees C). The enzyme kinetic studies revealed BmPI as a competitive inhibitor with a K-i value of 1.2 x 10(-9) M. In vitro studies with BmPI indicated measurable inhibitory activity on total gut proteolytic enzymes of H. armigera (IC(50)2.0 mu g/ml) and bovine trypsin. BmPI supplemented artificial diet caused dose dependent mortality and reduction in growth and weight. The fertility and fecundity of H. armigera, declined whereas the larval-pupal duration of the insect life cycle extended. These detrimental effects on H. armigera suggest the usefulness of BmPl in insect pest management of food crops. (C) 2014 Elsevier Ltd. All rights reserved.

An Evaluation of the Effectiveness of a Charged Bilayered Conducting Fine Mesh as a Dust Filter

Aim: To develop a mesh meant to be mounted on a windowpane that will act as a barrier for dust, while allowing wind to pass freely. Materials and Methods: Two small metal meshes separated at 1 cm, connected to an electrostatic generator and holding opposite charges are used. A videographic analysis has been performed. Results: The charged bilayered mesh was able to prevent a large portion of dust from passing through. Conclusion: The device is a simple, economical, and reliable way of reducing the entry of dust into a room, easing the need for periodic cleaning, and thus creating a healthier environment for the inhabitants of the building. It also has potential space applications.

Stress-strain fields and the effectiveness shear properties for three-phase composites with imperfect interface

Based on the 'average stress in the matrix' concept of Mori and Tanaka (:Mori, T., Tanaka, K., 1973. Average stress in matrix and average elastic energy of materials with misfitting inclusion. Acta Metall. 21, 571-580) a micromechanical model is presented for the prediction of the elastic fields in coated inclusion composites with imperfect interfaces. The solutions of the effective elastic moduli for this kind of composite are also obtained. In two kinds of composites with coated particulates and fibers, respectively, the interface imperfections are takes to the assumption that the interface displacement discontinues are linearly related to interface tractions like a spring layer of vanishing thickness. The resulting effective shear modulus for each material and the stress fields in the composite are presented under a transverse shear loading situation.

Evaluation of the Effectiveness of Representative Methods for Determining Young's Modulus and Hardness from Instrumented Indentation Data

The effectiveness of Oliver & Pharr's (O&P's) method, Cheng & Cheng's (C&C's) method, and a new method developed by our group for estimating Young's modulus and hardness based on instrumented indentation was evaluated for the case of yield stress to reduced Young's modulus ratio (sigma(y)/E-r) >= 4.55 x 10(-4) and hardening coefficient (n) <= 0.45. Dimensional theorem and finite element simulations were applied to produce reference results for this purpose. Both O&P's and C&C's methods overestimated the Young's modulus under some conditions, whereas the error can be controlled within +/- 16% if the formulation was modified with appropriate correction functions. Similar modification was not introduced to our method for determining Young's modulus, while the maximum error of results was around +/- 13%. The errors of hardness values obtained from all the three methods could be even larger and were irreducible with any correction scheme. It is therefore suggested that when hardness values of different materials are concerned, relative comparison of the data obtained from a single standard measurement technique would be more practically useful. It is noted that the ranges of error derived from the analysis could be different if different ranges of material parameters sigma(y)/E-r and n are considered.

Investigating the hydrothermal growth of zinc oxide nanostructures through seed layer control

Controlling the growth of ZnO nanostructures for photovoltaic applications will ensure greater device efficiency and parameter control. This paper reports on methods to engineer the morphology and tailor the nanostructure growth direction through the hydrothermal synthesis method. Effective control is achieved through the use of a sputtered zinc layer together with modifications of the growth solution. These nanostructures have been developed with a view to incorporation into excitonic solar cells, and methods to improve surface stability using a fully aqueous synthesis method will be discussed. © by Oldenbourg Wissenschaftsverlag, München.

Finding space to mental health : promoting mental health in adolescents (12 to 14 year olds): preliminary results of the intervention's effectiveness

Resumen: La salud mental y el bienestar son fundamentales para nuestra capacidad colectiva y individual como seres humanos de pensar, de exteriorizar los sentimientos, de establecer y mantener relaciones, para estudiar, para perseguir las actividades de ocio, para tomar decisiones diarias y para disfrutar de una vida plena. Una adolescencia saludable es un prerrequisito para una vida adulta saludable. Sin embargo, la realidad actual presenta un panorama preocupante. La formación del capital mental individual y colectivo - especialmente en las primeras etapas de la vida - está siendo retenida por una serie de riesgos evitables para la salud mental (World Health Organization [WHO], 2013). Los adolescentes del sur de Europa (región que ha sido más severamente afectada por la crisis financiera; e.g., Portugal) son señalados como un grupo extremadamente vulnerable, ya que su salud mental fácilmente podría ser influenciada por las dificultades económicas de sus padres y la escasez de solidaridad social (European Parliament, 2012). La promoción de la salud mental de los adolescentes es considerada como una preocupación fundamental (WHO, 2005a, 2013). En este ámbito, las intervenciones centradas en la promoción de la literacía de la salud mental han revelado importantes ventajas en la prevención, reconocimiento, intervención precoz y la reducción del estigma (Pinfold, Stuart, Thornicroft & Arboleda-Florez, 2005; Pinfold, Toulmin, Thornicroft, Huxley, Farmer & Graham, 2003; Schulze, Richter-Werling, Matschinger & Angermeyer, 2003; Stuart, 2006). En consonancia con los marcos de promoción de la salud mentales propuestos por la Organización Mundial de la Salud (2005a), tenemos que involucrar a jóvenes en los ambientes donde interactúan (Burns, 2011). Las escuelas son implícitamente uno de los locales más importantes para la promoción de la salud mental de los adolescentes (Barry, Clarke, Jenkins & Patel, 2013; WHO, 2001). El proyecto “Abrir Espacio para la Salud Mental – Promoción de la salud mental en adolescentes (12-14 años)” tiene como objetivo incrementar literacía de la salud mental en los jóvenes. En el primer año se ha desarrollado un instrumento de evaluación - Mental Health Literacy questionnaire (MHLq) - y la intervención para la promoción de la salud mental. La intervención consiste en 2 sesiones, 90 minutos cada una, implementadas con intervalo de una semana. Siguen una metodología interactiva, utilizando dinámicas de grupo, videos, música y discusión. El estudio de la eficacia de la intervención se lleva a cabo mediante un análisis pre y pos-test con el MHLq, utilizando un grupo experimental y un grupo de control. Este artículo presenta los resultados preliminares de la eficacia de la intervención de promoción de la salud mental en una muestra de 100 adolescentes portugueses (12-14 años). El pos-test mostró un incremento de los niveles de conocimientos de salud mental y estrategias de autoayuda. Los resultados sugieren que la intervención desarrollada parece ser adecuada al objetivo propuesto y refuerzan la creencia de que intervenciones escolares, sistemáticas y sostenibles, para la promoción de la salud mental con jóvenes, es un enfoque prometedor para la promoción de la literacía de la salud mental (Schulze et al., 2003; Rickwood et al., 2005; Corrigan et al., 2007; WHO, 2010).