Fig. 7

A model presenting symbiotic events and the transcriptomic responses in early-adult stage of maternal nematodes, and their interpretation in relevance to symbiosis with Photorhabdus bacteria. Colonization processes involve two-way crosstalk between host and symbiont. From the nematode host side, based on gene expression profiling, expression of immune system components which are involved in the recognition of bacteria, bacteria-derived molecules and detection of any cellular perturbations caused by bacteria are observed. It leads to activation of signalling pathways and results in an array of host immune and defence responses such as autophagy, apoptosis and production of antimicrobial proteins. These effectors and mechanisms regulate symbiont bacterial numbers and help achieve successful symbiosis. INT9L/INT9R – posterior nematode intestinal cells; RGC- rectal gland cells