Nature's Swiss Army Knives: Ovipositor Structure Mirrors Ecology in a Multitrophic Fig Wasp Community

Resource partitioning is facilitated by adaptations along niche dimensions that range from morphology to behaviour. The exploitation of hidden resources may require specially adapted morphological or sensory tools for resource location and utilisation. Differences in tool diversity and complexity can determine not only how many species can utilize these hidden resources but also how they do so.The sclerotisation, gross morphology and ultrastructure of the ovipositors of a seven-member community of parasitic wasps comprising of gallers and parasitoids developing within the globular syconia (closed inflorescences) of Ficus racemosa (Moraceae) was investigated. These wasps also differ in their parasitism mode (external versus internal oviposition) and their timing of oviposition into the expanding syconium during its development. The number and diversity of sensilla, as well as ovipositor teeth, increased from internally ovipositing to externally ovipositing species and from gallers to parasitoids. The extent of sclerotisation of the ovipositor tip matched the force required to penetrate the syconium at the time of oviposition of each species. The internally ovipositing pollinator had only one type of sensillum and a single notch on the ovipositor tip. Externally ovipositing species had multiple sensilla types and teeth on their ovipositors. Chemosensilla were most concentrated at ovipositor tips while mechanoreceptors were more widely distributed, facilitating the precise location of hidden hosts in these wasps which lack larval host-seeking behaviour. Ovipositor traits of one parasitoid differed from those of its syntopic galler congeners and clustered with those of parasitoids within a different wasp subfamily. Thus ovipositor tools can show lability based on adaptive necessity, and are not constrained by phylogeny.Ovipositor structure mirrored the increasingly complex trophic ecology and requirements for host accessibility in this parasite community. Ovipositor structure could be a useful surrogate for predicting the biology of parasites in other communities

OptForce: An Optimization Procedure for Identifying All Genetic Manipulations Leading to Targeted Overproductions

Computational procedures for predicting metabolic interventions leading to the overproduction of biochemicals in microbial strains are widely in use. However, these methods rely on surrogate biological objectives (e.g., maximize growth rate or minimize metabolic adjustments) and do not make use of flux measurements often available for the wild-type strain. In this work, we introduce the OptForce procedure that identifies all possible engineering interventions by classifying reactions in the metabolic model depending upon whether their flux values must increase, decrease or become equal to zero to meet a pre-specified overproduction target. We hierarchically apply this classification rule for pairs, triples, quadruples, etc. of reactions. This leads to the identification of a sufficient and non-redundant set of fluxes that must change (i.e., MUST set) to meet a pre-specified overproduction target. Starting with this set we subsequently extract a minimal set of fluxes that must actively be forced through genetic manipulations (i.e., FORCE set) to ensure that all fluxes in the network are consistent with the overproduction objective. We demonstrate our OptForce framework for succinate production in Escherichia coli using the most recent in silico E. coli model, iAF1260. The method not only recapitulates existing engineering strategies but also reveals non-intuitive ones that boost succinate production by performing coordinated changes on pathways distant from the last steps of succinate synthesis

Massively Parallel Sequencing and Analysis of the Necator americanus Transcriptome

The blood-feeding hookworm Necator americanus infects hundreds of millions of people. To elucidate fundamental molecular biological aspects of this hookworm, the transcriptome of adult Necator americanus was studied using next-generation sequencing and in silico analyses. Contigs (n = 19,997) were assembled from the sequence data; 6,771 of them had known orthologues in the free-living nematode Caenorhabditis elegans, and most encoded proteins with WD40 repeats (10.6%), proteinase inhibitors (7.8%) or calcium-binding EF-hand proteins (6.7%). Bioinformatic analyses inferred that C. elegans homologues are involved mainly in biological pathways linked to ribosome biogenesis (70%), oxidative phosphorylation (63%) and/or proteases (60%). Comparative analyses of the transcriptomes of N. americanus and the canine hookworm, Ancylostoma caninum, revealed qualitative and quantitative differences. Essential molecules were predicted using a combination of orthology mapping and functional data available for C. elegans. Further analyses allowed the prioritization of 18 predicted drug targets which did not have human homologues. These candidate targets were inferred to be linked to mitochondrial metabolism or amino acid synthesis. This investigation provides detailed insights into the transcriptome of the adult stage of N. americanus

LRP-1 Promotes Cancer Cell Invasion by Supporting ERK and Inhibiting JNK Signaling Pathways

Background: The low-density lipoprotein receptor-related protein-1 (LRP-1) is an endocytic receptor mediating the clearance of various extracellular molecules involved in the dissemination of cancer cells. LRP-1 thus appeared as an attractive receptor for targeting the invasive behavior of malignant cells. However, recent results suggest that LRP-1 may facilitate the development and growth of cancer metastases in vivo, but the precise contribution of the receptor during cancer progression remains to be elucidated. The lack of mechanistic insights into the intracellular signaling networks downstream of LRP-1 has prevented the understanding of its contribution towards cancer. Methodology/Principal Findings: Through a short-hairpin RNA-mediated silencing approach, we identified LRP-1 as a main regulator of ERK and JNK signaling in a tumor cell context. Co-immunoprecipitation experiments revealed that LRP-1 constitutes an intracellular docking site for MAPK containing complexes. By using pharmacological agents, constitutively active and dominant-negative kinases, we demonstrated that LRP-1 maintains malignant cells in an adhesive state that is favorable for invasion by activating ERK and inhibiting JNK. We further demonstrated that the LRP-1-dependent regulation of MAPK signaling organizes the cytoskeletal architecture and mediates adhesive complex turnover in cancer cells. Moreover, we found that LRP-1 is tethered to the actin network and to focal adhesion sites and controls ERK and JNK targeting to talin-rich structures. Conclusions: We identified ERK and JNK as the main molecular relays by which LRP-1 regulates focal adhesion disassembly of malignant cells to support invasion

Electron microscopy of quasi-crystals in rapidly solidified Al-14% Mn alloys

Recently Shechtman et al. (1) have reported a new phase in rapidly solidified Al-14at% Mn alloys. The diffraction patterns from this phase correspond to an icosahedral point group symmetry which is inconsistent with lattice translation, The observation is consistent with a long range icosahedral orientational order (termed quasi-crystal) modelled by using Penrose lattice (2,3). A second model proposed by 5achdev and Nelson (4) postulates a superposition of density waves with an icosahedral symmetry. These investigators considered stars composed of 12 vertices, 30 edges or 20 faces of a regular lcosahedron with the basis vectors comprising the stars being incommensurate in nature, Using Landau theory, they developed the hierarchy of spots in reciprocal space for vertex, edge and face models. These models are the counter part of simple cubic, f.c.c, and b.c.c, phases in normal crystals derived from an octahedron" These three types of quasi-crystals cannot be distinguished in three and five fold symmetry positions. However, the two fold symmetry shows a marked difference and hence a particular model can be identified. Additionally as pointed out by Levine and Steinhardt (3), the concept of quasi crystals can also be extended to irregular polyhedra

Electron microscopy and diffraction of icosahedral and decagonal quasicrystals in aluminum-manganese alloys

Electron microscopy observations on the morphol. of icosahedral and decagonal quasicrystals in Al-Mn alloys were interpreted in favor of a heterogenous nucleation mode. The transition of icosahedral quasicrystals from nonfacetted dendrites to facetted particles occurs as a function of compn. While the variety of electron diffraction patterns expected from icosahedral quasicrystals was demonstrated for a no. of alloys, subtle intensity differences exist among analogous patterns from Al-Mn, Al-Cr, Al-Mn-Si, and Mg-Al-Zn-Cu alloys. Electron diffraction patterns from decagonal quasicrystals are understood on the basis of an edge-centered icosahedral as opposed to a vertex-centered icosahedron for icosahedral quasicrystals. Truncation from 2-dimensional quasicrystals is discussed

Electron Microscopy of Quasi-Crystals and Related Structures

Systematic electron microscopy of quasi crystals in an A1-14 at \% Mn alloy has been carried out. High resolution imaging reveals fringes with spacings in the ratio of 1:\tau. Besides 5-3-2 synnetry axes, other important zones of electron diffraction patterns are experimentally determined and compared with those generated by Landau grneration technique and by projection technique. It has been shown that the 'T' phase, which often co-exits with quasicrystal, is closely related to it and can be treated as a two dimensional quasiperiodic crystal stacked periodically along an icosahedral vector of a true quasi periodic incommensurate modulation in three, two and one dimensions. The quasi crystal, the 'T' phase and vacancy ordered \tau phases and the respective real life examples of such modulations

On the variety of electron diffraction patterns from quasicrystals

A new exciting era in the study of rapidly solidified alloys has been ushered in by the discovery of a quasicrystalline phase in an Al-1O%Mn alloy by Shechtman et al. (l). The fact that a quasicrystal diffracts electrons and X-rays like a single crystal provides a powerful approach for exploring the atomic configuration in these alloys. Shechtman et al deduced the icosahedral point group symmetry exhibited by quasicrystals on the basis of a set of three electron diffraction patterns showing 5-fold, 3-fold and 2-fold axes of symmetry with appropriate angular relationships. The exotic crystallography of quasicrystals has been recently reviewed by Nelson and Halperin (2)