Ontology highlight
ABSTRACT:
PROVIDER: PRJNA1314498 | ENA |
REPOSITORIES: ENA
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Project description:Entomopathogenic nematodes (EPNs) of the genera Heterorhabditis are obligate and lethal insect parasites. In recent years they have been used increasingly as biological control agents. These EPNs are symbiotically associated with bacteria of the genera Photorhabdus. The bacterial symbionts are essential to kill the host (within 24-48 hours) and digest its tissues to provide nutrients for themselves as well for expanding nematodes. Drosophila larvae are suitable insect hosts and part of the tripartite model system we used before to show the importance of haemolymph clotting and eicosanoids during the infection. We used the well-established tripartite model (Drosophila, nematodes, bacteria), DNA chips and bioinformatic tools to compare gene expression in non-infected and infected fly larvae. We focused on the early time point of nematode infection and therefore infected Drosophila larvae using H. bacteriophora harbouring GFP-labelled P. luminescens bacteria. Infected (GFP positive) larvae were collected 6 hours after infection.
2014-03-07 | E-MTAB-1542 | biostudies-arrayexpress
Project description:Entomopathogenic nematodes (EPNs) are unique parasitic nematodes due to their symbiosis with entomopathogenic bacteria and their ability to kill insect hosts quickly after infection. Although it has been widely believed that EPNs rely on their bacterial partners for killing insect hosts, compelling evidence from previous studies challenges this model. We developed an improved method of activating millions of Steinernema carpocapsae infective juveniles (IJs) in vitro to harvest excreted/secreted (ES) proteins for bioactivity tests and proteomics analysis. We found that a low dose of the ES proteins from early activated nematodes is lethal to Drosophila melanogaster adults within 2-6 hours. We analyzed the protein composition of this venom using mass spectrometry and identified 472 proteins. Many of these venom proteins share high homology with those of vertebrate-parasitic nematodes. Among many different families of proteins found in the venom, proteases and protease inhibitors are especially abundant. Some toxin-related proteins such as Shk domain-containing proteins were also detected. We further analyzed the transcriptomes of individual non-activated IJs and nematodes that were activated in vitro and in vivo, which revealed a dramatic shift in gene expression during IJ activation. By comparing the whole transcriptomes and the genes encoding venom proteins between the in vitro and in vivo activated nematodes, we confirmed that the in vitro activation is a good approximation of the in vivo process. In summary, our findings strongly support a new model that S. carpocapsae and likely other Steinernema EPNs have a more active role in contributing to the pathogenicity of the nematode-bacterium complex than simply relying on their symbiotic bacteria. Furthermore, we propose that EPNs are a good model system for investigating vertebrate- and human-parasitic nematodes, especially regarding the function of ES products.
2017-03-27 | GSE89961 | GEO