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.

Stress states in individual Si particles of a cast Al-Si alloy: Micro-Raman analysis and microstructure based modeling

The stress states in Si particles of cast Al-Si based alloys depend on its morphology and the heat treatment given to the alloy. The Si particles fracture less on modification and fracture more in the heat treated condition. An attempt has been made in this work to study the effect of heat treatment and Si modification on the stress states of the particles. Such understanding will be valuable for predicting the ductility of the alloy. The stress states of Si particles are estimated by Raman technique and compared with the microstructure-based FEM simulations. Combination of Electron Back-Scattered Diffraction (EBSD) and frequency shift, polarized micro-Raman technique is applied to determine the stress states in Si particles with (111) orientations. Stress states are measured in the as-received state and under uniaxial compression. The residual stress, the stress in the elastic-plastic regime and the stress which causes fracture of the particles is estimated by Raman technique. FEM study demonstrates that the stress distribution is uniform in modified Si, whereas the unmodified Si shows higher and more complex stress states. The onset of plastic flow is observed at sharp corners of the particles and is followed by localization of strain between particles. Clustering of particles generates more inhomogeneous plastic strain in the matrix. Particle stress estimated by Raman technique is in agreement with FEM calculations. (C) 2014 Elsevier B.V. All rights reserved.

Novel multimeric IL-1 receptor antagonist for the treatment of rheumatoid arthritis

Protein therapeutics targeting inflammatory mediators have shown great promise for the treatment of autoimmunities such as rheumatoid arthritis (RA). However, a significant challenge in this area has been their low in vivo stability and consequently their severely compromised therapeutic efficacy. One such therapeutic molecule IL-1 receptor antagonist (IL-1ra), used in the treatment of rheumatoid arthritis, has displayed only modest efficacy in human clinical trials owing to its short biological half-life. Herein, we report a novel approach to conglomerate individual protein entities into a drug depot by incorporation of an amyloidogenic motif Lys-Phe-Phe-Glu (KFFE) thereby dramatically improving their systemic persistence and in turn their therapeutic efficacy in a mice model of autoimmune arthritis. (C) 2014 Elsevier Ltd. All rights reserved.

Individual and combined additions of calcium and antimony on microstructure and mechanical properties of squeeze-cast AZ91D magnesium alloy

The effects of combined additions of Ca and Sb on the microstructure and tensile properties of AZ91D alloy fabricated by squeeze-casting have been investigated. For comparison, the same has also been studied with and without individual additions of Ca and Sb. The results indicate that both individual and combined additions refine the grain size and beta-Mg17Al12 phase, which is more pronounced with combined additions. Besides alpha-Mg and beta-Mg17Al12 phases, a new reticular Al2Ca and rod-shaped Mg3Sb2 phases are formed following individual additions of Ca and Sb in the AZ91D alloy. With combined additions, an additional Ca2Sb phase is formed suppressing Mg3Sb2 phase. Additions of both Ca and Sb increase yield strength (YS) at both ambient and elevated temperatures up to 200 degrees C. However, both ductility and ultimate tensile strength (UTS) decrease first up to 150 degrees C and then increase at 200 degrees C. The increase in YS is attributed to the refinement of grain size, whereas, ductility and UTS are deteriorated by the presence of brittle Al2Ca, Mg3Sb2 and Ca2Sb phases. The best tensile properties are obtained in the AZXY9110 alloy owing to the presence of lesser amount of brittle Al2Ca and Ca2Sb phases resulted from the optimum content of 1.0Ca and 0.3Sb (wt%). The fracture surface of the tensile specimen tested at ambient temperature reveals cleavage failure that changes to quasi-cleavage at 200 degrees C. The squeeze-cast alloys exhibited better tensile properties as compared to that of the gravity-cast alloys nullifying the detrimental effects of Ca and/or Sb additions. (C) 2014 Elsevier B.V. All rights reserved.

Piezoelectric properties of individual nanocrystallites of Ba0.85Ca0.15Zr0.1Ti0.9O3 obtained by oxalate precursor route

Nanocrystalline Ba0.85Ca0.15Zr0.1Ti0.9O3 (BCZT) powder was synthesized via the complex oxalate precursor route at a relatively low temperature (800 degrees C/5 h). The phase formation temperature of BCZT at nanoscale was confirmed by thermogravimetric (TG), differential thermal analysis (DTA) followed by X-ray powder diffraction (XRD) studies. Fourier transform infrared (FTIR) spectroscopy was carried out to confirm the complete decomposition of oxalate precursor into BCZT phase. The XRD and profile fitting revealed the coexistence of cubic and tetragonal phases and was corroborated by Raman study. Transmission electron microscopy (TEM) carried out on 800 degrees C and 1000 degrees C/5 h heat treated BCZT powder revealed the crystallite size to be in the range of 20-50 nm and 40-200 nm respectively. The optical band gap for BCZT nanocrystalline powder was obtained using Kubelka Munk function and was found to be around 3.12 +/- 0.02 eV and 3.03 +/- 0.02 eV respectively for 800 degrees C (20-50 nm) and 1000 degrees C/5 h (40-200 nm) heat treated samples. The piezoelectric properties were studied for two different crystallite sizes (30 and 70 nm) using a piezoresponse force microscope (PFM). The d(33) coefficients obtained for 30 nm and 70 nm sized crystallites were 4 pm V-1 and 47 pm V-1 respectively. These were superior to that of BaTiO3 nanocrystal (approximate to 50 nm) and promising from a technological/industrial applications viewpoint.

Males and females of the social wasp Ropalidia marginata do not differ in their cuticular hydrocarbon profiles and do not seem to use any long-distance volatile mate attraction cues

Sex pheromones are vital in communication between individuals belonging to opposite sexes and form an integral part of the reproductive biology of various species. Among insects, sexual dimorphism in CHCs has been reported from diverse taxa spanning seven different orders, and thereby CHCs have been implicated as sex pheromones. Because males and females of the primitively eusocial wasp Ropalidia marginata touch each other with their antennae during mating, before engaging in sperm transfer, a sex pheromone that is perceived via contact chemosensation through the antennae can possibly exist in this species. Since CHCs have been implied as sex pheromones in various insects (including hymenopterans), and since sexual dimorphism of CHCs should be an obligatory prerequisite for them to act as sex pheromones, we investigated whether males and females of R. marginata differ in their CHC profiles. We found only nonvolatile CHCs, and our results show absence of sexual dimorphism in CHCs, suggesting that CHCs do not function as sex pheromone in this species. A behavioral assay failed to show presence of mate attraction at a distance, thereby showing the absence of volatile long-distance mate attraction cues (that may originate from sources other than and in addition to CHCs).

Homing abilities of the tropical primitively eusocial paper wasp Ropalidia marginata

Compared to our extensive knowledge about the navigation and homing abilities of ants and bees, we know rather little about these phenomena in social wasps. Here, we report the homing abilities of the tropical primitively eusocial wasp Ropalidia marginata and the factors that affect their homing success. To determine from how far these wasps can return to their nests, we transported foragers blindfold and released them at gradually increasing distances from their nests in four cardinal directions. Their homing success was determined by checking their presence on their nests on three consecutive nights. All foragers (56 individuals, 115 releases) returned back from an area of 0.73 +/- A 0.25 km(2) on the day of release (minimal homing area), whereas 83.8 % of the foragers (217 individuals, 420 releases) returned when we enlarged the area of release to 6.22 +/- A 0.66 km(2) around their nests (maximal homing area). Of 66 releases, no wasps returned from beyond the maximal homing area. The minimal homing area might be familiar to the foragers because they probably routinely forage in this area and the maximal homing area represents the maximum distances from which the wasps are capable of returning to their nests, with or without familiarity.

Evolution of social behaviour in the primitively eusocial wasp Ropalidia marginata: do we need to look beyond kin selection?

Ropalidia marginata is a primitively eusocial wasp widely distributed in peninsular India. Although solitary females found a small proportion of nests, the vast majority of new nests are founded by small groups of females. In suchmultiple foundress nests, a single dominant female functions as the queen and lays eggs, while the rest function as sterile workers and care for the queen's brood. Previous attempts to understand the evolution of social behaviour and altruism in this species have employed inclusive fitness theory (kin selection) as a guiding framework. Although inclusive fitness theory is quite successful in explaining the high propensity of the wasps to found nests in groups, several features of their social organization suggest that forces other than kin selection may also have played a significant role in the evolution of this species. These features include lowering of genetic relatedness owing to polyandry and serial polygyny, nest foundation by unrelated individuals, acceptance of young non-nest-mates, a combination of well-developed nest-mate recognition and lack of intra-colony kin recognition, a combination of meek and docile queens and a decentralized self-organized work force, long reproductive queues with cryptic heir designates and conflict-free queen succession, all resulting in extreme intra-colony cooperation and inter-colony conflict.

Magnitude and Origin of Electrical Noise at Individual Grain Boundaries in Graphene

Grain boundaries (GBs) are undesired in large area layered 2D materials as they degrade the device quality and their electronic performance. Here we show that the grain boundaries in graphene which induce additional scattering of carriers in the conduction channel also act as an additional and strong source of electrical noise especially at the room temperature. From graphene field effect transistors consisting of single GB, we find that the electrical noise across the graphene GBs can be nearly 10 000 times larger than the noise from equivalent dimensions in single crystalline graphene. At high carrier densities (n), the noise magnitude across the GBs decreases as proportional to 1/n, suggesting Hooge-type mobility fluctuations, whereas at low n close to the Dirac point, the noise magnitude could be quantitatively described by the fluctuations in the number of propagating modes across the GB.

How to be a fig wasp parasite on the fig-fig wasp mutualism

The nursery pollination mutualism between figs and pollinating fig wasps is based on adaptations that allow wasps to enter the enclosed inflorescences of figs, to facilitate seed set, and to have offspring that develop within the nursery and that leave to enter other inflorescences for pollination. This closed mutualistic system is not immune to parasitic fig wasps. Although the life histories and basic biology of the mutualists have been investigated, the biology of the fig wasp parasites has been severely neglected. This review brings together current knowledge of the many different ways in which parasites can enter the system, and also points to the serious lacunae in our understanding of the intricate interactions between gallers, kleptoparasites, seed eaters and parasitoids within this mutualism.