Project description:We report the application of next generation RNA sequencing to analyze the transcriptional response of Drosophila adult flies to infection by the insect pathogenic nematodes Heterorhabditis bacteriophora and their mutualistic bacteria Photorhabdus luminescens, either separately or together. We find that Heterorhabditis and Photorhabdus differentially modulate a large number of genes, many of which participate in metabolic functions, stress responses, repression of gene transcription and neuronal activities. We have also identified Drosophila genes with potential role in nematode recognition and others with putative anti-nematode properties. These findings generate novel insights into how the host immune function is shaped to respond against nematode parasites and their associated bacteria. Transcriptional profiles of Drosophila wild-type adult flies infected with Heterorhabditis bacteriophora carrying or lacking Photorhabdus or the bacteria alone were generated at 12 and 30 hours post infection using Illumina deep sequencing technology.
Project description:We report the application of next generation RNA sequencing to analyze the transcriptional response of Drosophila adult flies to infection by the insect pathogenic nematodes Heterorhabditis bacteriophora and their mutualistic bacteria Photorhabdus luminescens, either separately or together. We find that Heterorhabditis and Photorhabdus differentially modulate a large number of genes, many of which participate in metabolic functions, stress responses, repression of gene transcription and neuronal activities. We have also identified Drosophila genes with potential role in nematode recognition and others with putative anti-nematode properties. These findings generate novel insights into how the host immune function is shaped to respond against nematode parasites and their associated bacteria.
Project description:Secretion systems are used as weapons by a variety of Gram-negative bacteria. Among them the Type VI Secretion System (T6SS) gained more interest throughout the last years. The system functions as a molecular nano-weapon: it is used in inter-kingdom competition by various bacteria to deliver toxic effectors in target cells. Here we describe the role of the T6SS in Photorhabdus laumondii subsp. laumondii strain DJC, an entomopathogenic biocontrol agent able to live in different environmental niches, such as in symbiosis with nematodes and in the rhizosphere on plant roots. Using bioinformatic and protein motif analyses we identified four T6SS gene clusters (T6SS-1, T6SS-2, T6SS-3 and T6SS-4) and multiple orphan T6SS related genes in the genome of P. laumondii. Furthermore, we highlighted 11 T6SS effector-immunity pairs, including three undescribed membrane disrupting effectors, each with putatively different antibacterial activities. By label-free mass spectrometry of P. laumondii wild type cells and respective T6SS-deficient strains, we could point out a cross-link between T6SS and other Photorhabdus’ virulence related mechanisms such as PVCs, T3SS and pyocins. Furthermore, a change in motility as well as in the secondary metabolism was observed upon T6SS-deficiency. Here, we shed light on the T6SS in P. laumondii DJC and suggesting a cross-link of various virulence mechanisms, which could help to gain knowledge on T6SS and better figure out the Photorhabdus ability to live in polymicrobial environments.