Phenoloxidase activity acts as a mosquito innate immune response against infection with semliki forest virus

Several components of the mosquito immune system including the RNA interference (RNAi), JAK/STAT, Toll and IMD pathways have previously been implicated in controlling arbovirus infections. In contrast, the role of the phenoloxidase (PO) cascade in mosquito antiviral immunity is unknown. Here we show that conditioned medium from the Aedes albopictus-derived U4.4 cell line contains a functional PO cascade, which is activated by the bacterium Escherichia coli and the arbovirus Semliki Forest virus (SFV) (Togaviridae; Alphavirus). Production of recombinant SFV expressing the PO cascade inhibitor Egf1.0 blocked PO activity in U4.4 cell- conditioned medium, which resulted in enhanced spread of SFV. Infection of adult female Aedes aegypti by feeding mosquitoes a bloodmeal containing Egf1.0-expressing SFV increased virus replication and mosquito mortality. Collectively, these results suggest the PO cascade of mosquitoes plays an important role in immune defence against arboviruses

Cloning retinoid and peroxisome proliferator-activated nuclear receptors of the Pacific oyster and in silico binding to environmental chemicals

This is the final version of the article. Available from Public Library of Science via the DOI in this record.Disruption of nuclear receptors, a transcription factor superfamily regulating gene expression in animals, is one proposed mechanism through which pollution causes effects in aquatic invertebrates. Environmental pollutants have the ability to interfere with the receptor's functions through direct binding and inducing incorrect signals. Limited knowledge of invertebrate endocrinology and molecular regulatory mechanisms, however, impede the understanding of endocrine disruptive effects in many aquatic invertebrate species. Here, we isolated three nuclear receptors of the Pacific oyster, Crassostrea gigas: two isoforms of the retinoid X receptor, CgRXR-1 and CgRXR-2, a retinoic acid receptor ortholog CgRAR, and a peroxisome proliferator-activated receptor ortholog CgPPAR. Computer modelling of the receptors based on 3D crystal structures of human proteins was used to predict each receptor's ability to bind to different ligands in silico. CgRXR showed high potential to bind and be activated by 9-cis retinoic acid and the organotin tributyltin (TBT). Computer modelling of CgRAR revealed six residues in the ligand binding domain, which prevent the successful interaction with natural and synthetic retinoid ligands. This supports an existing theory of loss of retinoid binding in molluscan RARs. Modelling of CgPPAR was less reliable due to high discrepancies in sequence to its human ortholog. Yet, there are suggestions of binding to TBT, but not to rosiglitazone. The effect of potential receptor ligands on early oyster development was assessed after 24h of chemical exposure. TBT oxide (0.2μg/l), all-trans retinoic acid (ATRA) (0.06 mg/L) and perfluorooctanoic acid (20 mg/L) showed high effects on development (>74% abnormal developed D-shelled larvae), while rosiglitazone (40 mg/L) showed no effect. The results are discussed in relation to a putative direct (TBT) disruption effect on nuclear receptors. The inability of direct binding of ATRA to CgRAR suggests either a disruptive effect through a pathway excluding nuclear receptors or an indirect interaction. Our findings provide valuable information on potential mechanisms of molluscan nuclear receptors and the effects of environmental pollution on aquatic invertebrates.The study was funded by the Centre for Environment, Fisheries and Aquaculture Science (Cefas; https://www.cefas.co.uk) and by the University of Exeter (http://www.exeter.ac.uk)

ARTIFICIAL NEURAL NETWORKS FOR CONTROL AND MODELLING OF AN UNMANNED UNDERWATER VEHICLE

Due to their highly non-linear hydrodynamics and the unknown environmental conditions in which they operate, the control of Unmanned Underwater Vehicles (UUVs) poses serious difficulties for most classical design methods. This thesis investigates the use of Artificial Neural Networks (ANNs) when applied to the modelling and control of a UUV whilst following a varying seabed terrain and at differing surge velocities. Different control procedures are examined and their relative merits discussed in relation to the problem. The results of using an ANN to model the depth dynamics of the UUV at a single operating point and using this network model to train an ANN controller by use of Error Backpropagation are presented. In addition, a different control strategy is investigated, whereby, an ANN controller is trained by using the full mathematical model of the UUV and linear transfer function representations of its depth dynamics at specific operating points. The relative performances of using a feedforward ANN controller and a recurrent ANN controller are compared over different profiles as well as contrasting the relative merits of using Error Backpropagation, Chemotaxis and Alopex, as applied to the controller training task. In addition, the robustness of the optimum controller in the presence of disturbances and missions over unfamiliar terrain and at varying surge velocities are considered.The Royal Naval Engineering Colleg

Effects of paint-derived tributyltin on structure of estuarine nematode assemblages in experimental microcosms

A microcosm experiment was designed to evaluate the effects of different levels of paint-derived tributyltin (TBT), and different modes of exposure, on the diversity, feeding mode and assemblage structure of estuarine nematodes. Estuarine meiofauna were exposed to two types of treatments (mixture and deposit), containing uncontaminated sediment and sediment spiked with paint-derived TBT at 1 and 10 mg kg−1 for a duration of 4 and 8 weeks. In the mixture treatments, meiofauna assemblages were incubated in clean and contaminated sediments. In the deposit treatments meiofauna assemblages were exposed to the deposition of clean and contaminated sediments simulating the disposal of TBT-contaminated dredged material at sea. Effects of TBT on nematode species are likely to occur by (a) the uptake of leached TBT from the sediment pore water through their permeable cuticle, resulting in decreased diversity and increased changes in assemblage structure with increasing levels of TBT contamination, and (b) direct ingestion of paint-particles with food, resulting in a significant decline of nonselective deposit feeders in contaminated sediments. The numbers of many species differed greatly between mixture and deposit treatments. Results from multivariate analyses showed an immediate and dominant effect of burial on most nematode species in the deposit treatments compared to the longer-term effect of TBT contamination. The survival rates of nematode species in the top layer of these sediments depended on their ability to withstand TBT contamination as well as their potential to migrate, survive and reproduce in the deposit. This study unambiguously showed that the response of nematode species depended not only on the level of TBT contamination but also on the duration and mode of exposure to contaminated sediment, which should be taken into account when assessing the effects of TBT on aquatic communities

Two new peacock spider species of the genus Maratus (Araneae: Salticidae: Salticinae) from south-western Australia

The Australian endemic Peacock spider genus Maratus currently includes 97 species which are renowned for their elaborate courtship displays. Two new species are described from south-western Australia, M. fetcheri sp. nov. and M. harveyi sp. nov. Recently collected material has extended the range of M. madelineae Waldock, 2014. A brief summary of the courtship display for M. fetcheri sp. nov. is included

Toxicity characterization of organic contaminants in Industrialized UK estuaries and coastal waters

This report describes the isolation and identification of organic toxicants present in marine surface waters collected from industrially impacted areas around the UK in 1997. The characterization process utilized Toxicity Identification Evaluation (TIE) procedures that have been adapted for marine samples and a small volume bioassay using the marine copepod Tisbe battagliai. The dissolved organic content of bulk water samples was isolated using a layered solid phase extraction system to provide sample concentrates which were tested for acute toxicity. Where acute toxicity was demonstrated, the extracts were fractionated using reverse phase HPLC and tested further. Each fraction showing toxicity was then analysed by gas chromatography-mass spectrometry. The results of this investigation demonstrate that surface water concentrates collected from several impacted estuaries show acute toxicity. Organic extracts from surface waters may be concentrated using simple chromatographic techniques to induce toxicity in test species. Fractionation showed that the majority of this toxicity is associated with low to medium polarity contaminants. Compounds that were identified by gas chromatography-mass spectrometry as the possible cause of toxic effect include alkylphenols, alkyl substituted naphthalenes, alkyl-substituted fluorenes and dimethyl benzoquinone, however, the identity of certain toxic compounds remains unknown. It is concluded that the technique is a valuable tool in identifying compounds that may be potentially harmful to the aquatic environment. Copyright (C) 1999

Development of a Rockoon Launch Platform and a Sulfur Fuel Pulsed Plasma Thruster CubeSAT

Amateur rocket launches are unable to reach heights much above 30 km due to the high drag of the dense lower atmosphere. Using a balloon to rise to an altitude of 30 km before launching is one means to increase a rockets range. An overview of the concept and a summary of the launch history for the University of Washington rockoon (rocket / balloon) program are given. Such a system will be capable of providing an inexpensive and reduced complexity launch method for student projects. Additionally, the university has recently opened a CubeSAT laboratory to give students hands-on experience with satellite hardware. Once in orbit, CubeSAT missions are limited, in part, due to an inability of low power thrusters to offset atmospheric drag. Recent results show that a coaxial sulfur-fuel Pulsed Plasma Thruster can provide a impulse/energy ratio of 20 mN/kW from a 10 J discharge, double of what a similar geometry Teflon variant is capable of. This increase in performance can provide CubeSATs the propulsion necessary for station-keeping in orbit. With launches planned over the next five years, the University of Washington aims to launch a 3U CubeSAT from a rockoon on a suborbital flight as a student project