A crotonyl-CoA reductase-carboxylase independent pathway for assembly of unusual alkylmalonyl-CoA polyketide synthase extender units

Type I modular polyketide synthases assemble diverse bioactive natural products. Such multienzymes typically use malonyl and methylmalonyl-CoA building blocks for polyketide chain assembly. However, in several cases more exotic alkylmalonyl-CoA extender units are also known to be incorporated. In all examples studied to date, such unusual extender units are biosynthesized via reductive carboxylation of α, β-unsaturated thioesters catalysed by crotonyl-CoA reductase/carboxylase (CCRC) homologues. Here we show using a chemically-synthesized deuterium-labelled mechanistic probe, and heterologous gene expression experiments that the unusual alkylmalonyl-CoA extender units incorporated into the stambomycin family of polyketide antibiotics are assembled by direct carboxylation of medium chain acyl-CoA thioesters. X-ray crystal structures of the unusual β-subunit of the acyl-CoA carboxylase (YCC) responsible for this reaction, alone and in complex with hexanoyl-CoA, reveal the molecular basis for substrate recognition, inspiring the development of methodology for polyketide bio-orthogonal tagging via incorporation of 6-azidohexanoic acid and 8-nonynoic acid into novel stambomycin analogues

Revisiting the male-produced aggregation pheromone of the lesser mealworm, Alphitobius diaperinus (Coleoptera, Tenebrionidae): identification of a six-component pheromone from a Brazilian population

The lesser mealworm, Alphitobius diaperinus Panzer 1797 (Coleoptera: Tenebrionidae), is a cosmopolitan insect pest affecting poultry production. Due to its cryptic behavior, insecticide control is usually not efficient. Thus, sustainable and effective methods would have an enormous and positive impact in poultry production. The aim of this study was to confirm the identity of the male-produced aggregation pheromone for a Brazilian population of A. diaperinus and to evaluate its biological activity in behavioral assays. Six male-specific compounds were identified: (R)-limonene (1), (E)-ocimene (2), 2-nonanone (3), (S)-linalool (4), (R)-daucene (5), all described before in an American population, and a sixth component, (E,E)-α-farnesene (6), which is apparently exclusive to a Brazilian population. Y-Tube bioassays confirmed the presence of a male-produced aggregation pheromone and showed that all components need to be present in a similar ratio and concentration as emitted by male A. diaperinus to produce a positive chemotactic response

(2R,5S)-theaspirane identified as the kairomone for the banana weevil, Cosmopolites sordidus, from attractive senesced leaves of the host banana, Musa spp.

The principal active component produced by highly attractive senesced host banana leaves, Musa spp., for the banana weevil, Cosmopolites sordidus, is shown by coupled gas chromatography‐electroantennography (GC‐EAG), coupled GC‐mass spectrometry (GC‐MS), chemical synthesis and coupled enantioselective (chiral) GC‐EAG to be (2R,5S)‐theaspirane. In laboratory behaviour tests, the synthetic compound is as attractive as natural host leaf material and presents a new opportunity for pest control

Honey Plotter and the Web of Terror

Honeypots are a useful tool for discovering the distribution of malicious traffic on the Internet and how that traffic evolves over time. In addition, they allow an insight into new attacks appearing. One major problem is analysing the large amounts of data generated by such honeypots and correlating between multiple honeypots. Honey Plotter is a web-based query and visualisation tool to allow investigation into data gathered by a distributed honeypot network. It is built on top of a relational database, which allows great flexibility in the questions that can be asked and has automatic generation of visualisations based on the results of queries. The main focus is on aggregate statistics but individual attacks can also be analysed. Statistical comparison of distributions is also provided to assist with detecting anomalies in the data; helping separate out common malicious traffic from new threats and trends. Two short case studies are presented to give an example of the types of analysis that can be performed

Identification of volatile compounds involved in host location by Anthonomus grandis (Coleoptera: Curculionidae).

Na publicação: Maria C. Blassioli-Moraes

Pea aphid odorant-binding protein ApisOBP6 discriminates between aphid sex pheromone components, aphid alarm pheromone and a host plant volatile

Olfactory perception of pheromones in insects involves odorant-binding proteins (OBPs), relatively small proteins (ca.110-240 amino acid residues) that can bind reversibly to behaviourally active olfactory ligands. In this study, we investigated the binding in silico and in vitro of the aphid sex pheromone components (1R,4aS,7S,7aR)-nepetalactol and (4aS,7S,7aR)-nepetalactone and the aphid alarm pheromone (E)-β-farnesene by OBPs from the pea aphid, Acyrthosiphon pisum. Screening of protein models of ApisOBPs1-11 with the aphid sex pheromone components suggested that ApisOPB6 was a candidate. Fluorescence assays using ApisOBP6 suggested that ApisOBP6 was able to bind both sex pheromone components and discriminate from the aphid alarm pheromone and the generic plant compound (R/S)-linalool. Saturation transfer difference NMR experiments with ApisOBP6 yielded results consistent to those from the fluorescence experiments, with a clear interaction between ApisOBP6 and (4aS,7S,7aR)-nepetalactone. These results describe a novel interaction and potential function for ApisOBP6, point to pre-receptor odorant discrimination by OBPs, and provide a platform for investigating the function of other aphid olfactory proteins involved in aphid chemical ecology

Species- and context-dependent responses of green lacewings suggest a complex ecological role for methyl salicylate (Neuroptera: Chrysopidae)

Herbivore-induced plant volatiles (HIPVs) are important semiochemicals in multitrophic plant-insect interactions, attracting natural enemies of phytophagous insects. Numerous studies have reported attraction of natural enemies to the HIPV methyl salicylate, including green lacewings. However, previous reports provide conflicting data, as some studies report significant attraction, whereas others found moderate or no attraction, even for the same taxa. In the current study, we conducted field experiments in Hungary with methyl salicylate and known attractants for Chrysoperla spp. and Chrysopa spp. lacewings. Both males and females of Chrysoperla carnea species complex were attracted to methyl salicylate, but to a much lesser extent compared to phenylacetaldehyde, a previously known floral attractant. When presented in combination, methyl salicylate showed a synergistic effect, confirming results of previous research performed in Hungary. On the other hand, methyl salicylate did not attract Chrysopa formosa. When tested in combination with known sex attractants for C. formosa males, it synergized male attraction to the aphid sex pheromone component (1R,4aS,7S,7aR)-nepetalactol; however, in combination with squalene, no synergistic effect was found. The results suggest that the responses of green lacewings to methyl salicylate are context-dependent, and the ecological role of the compound may be more complex than previously expected

Challenges in the capture and dissemination of measurements from high-speed networks

The production of a large-scale monitoring system for a high-speed network leads to a number of challenges. These challenges are not purely technical but also socio-political and legal. The number of stakeholders in such monitoring activity is large including the network operators, the users, the equipment manufacturers and, of course, the monitoring researchers. The MASTS project (measurement at all scales in time and space) was created to instrument the high-speed JANET Lightpath network and has been extended to incorporate other paths supported by JANET(UK). Challenges the project has faced included: simple access to the network; legal issues involved in the storage and dissemination of the captured information, which may be personal; the volume of data captured and the rate at which these data appear at store. To this end, the MASTS system will have established four monitoring points each capturing packets on a high-speed link. Traffic header data will be continuously collected, anonymised, indexed, stored and made available to the research community. A legal framework for the capture and storage of network measurement data has been developed which allows the anonymised IP traces to be used for research purposes

A model for (re)building consumer trust in the food system

This manuscript version is made available per the publisher's Author self-archiving policy. Copyright © The Authors 2016. Published by Oxford University Press. All rights reserved.The article presents a best practice model that can be utilized by food system actors to assist with (re)building trust in the food system, before, during and after a food incident defined as ‘any situation within the food supply chain where there is a risk or potential risk of illness or confirmed illness or injury associated with the consumption of a food or foods’ (Commonwealth of Australia. National Food Incident Response Protocol. Commonwealth of Australia, Canberra, 2012). Interviews were undertaken with 105 actors working within the media, food industry and food regulatory settings across Australia, New Zealand (NZ) and the United Kingdom (UK). Interview data produced strategy statements, which indicated participant views on how to (re)build consumer trust in the food system. These included: (i) be transparent, (ii) have protocols and procedures in place, (iii) be credible, (iv) be proactive, (v) put consumers first, (vi) collaborate with stakeholders, (vii) be consistent, (viii) educate stakeholders and consumers, (ix) build your reputation and (x) keep your promises. A survey was designed to enable participants to indicate their agreement/disagreement with the ideas, rate their importance and provide further comment. The five strategies considered key to (re)building consumer trust were used to develop a model demonstrating best practice strategies for (re)building consumer trust in the food system before, during and after a food incident. In a world where the food system is increasingly complex, strategies for (re)building and fostering consumer trust are important. This study offers a model to do so which is derived from the views and experiences of actors working across the food industry, food regulation and the media