Publication details
New insights to insect response to the infection by nematobacterial complex
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| Year of publication | 2013 |
| Type | Conference abstract |
| MU Faculty or unit | |
| Citation | |
| 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. We detected approximately 650 genes whose expression was significantly influenced by nematobacterial infection caused by H. bacteriophora and P. luminescens. Most of them are upregulated upon infection including mainly the genes involved in antimicrobial response and development. Based on Gene Ontology annotation we identified several pathways, which could be involved in sealing and repairing the wound caused by invading nematodes. These results we compared with available data for other types infection caused by bacteria and parasitic wasps. Small group of genes were common for all three types of infection and approximately 25 genes were overlapping in each pairwise comparison. We focused on the genes expressed in the hemocytes and fat body, respectively and we subjected selected candidate genes to functional tests. We tested the effect of mutations or knockdown of selected genes for the susceptibility of flies to the nematobacterial infection. The overlap between the protective genes and genes induced by the nematobacterial infection was not complete. Therefore, we assume that only a fraction of the genes involved in the protection of infected larvae from death are induced by the nematobacterial infection. Our research is supported by research grants from the Swedish Research Council (VR-NT 2010-5118), the Swedish Foundation for International Cooperation in Research and Higher Education (STINT) and by grant from Ministry of Agriculture of Czech Republic (NAZV-KUS QJ1210047). |
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