Special anti-attachment diets

There are several ongoing activities in WP2. Currently we are analysing intestinal contents of fish fed special anti-attachment diets.  The idea is to follow the trajectory of several suspected bioactive substances all the way from the feed ingredient to the target organs in fish and lice. Now we are trying to determine the contents of bioactive compounds in the intestinal tract, to see where exactly they get absorbed or possibly modified. To completely understand metabolism of a dietary ingredient and its beneficial effects we need to understand its transport via blood and also where it gets accumulated.  Samples from two time points will be analysed to address the dynamics of the involved processes. Therefore, our next effort would be to profile blood and target organs, including spleen and skin for the content of involved bioactive compounds and their metabolites.

Another ongoing activity in WP2 is to develop an in vitro test system, to see how the lice react to several attractants and repellents added to the water. There are ongoing discussions on which compounds we should test, in addition to the ones already shown to be potent attractants and repellents. We are currently reviewing the synthetic chemistry literature to estimate if this approach holds promise for the anti-attachment research program; namely modification of existing molecules could potentiate their anti-lice properties while avoiding adverse side-effects for the host. At NVH, we have an ongoing study (the simple exposure in the bottle approach) with 2-aminoacetophenon, one of the repellent substances isolated from turbot mucus. We hope this research could help us better understand gene expression changes related to avoidance behaviour and transition from free-floating to attached life stages.

Finally, analyses of the effects of steroid sex hormones (oestrogen and testosterone) from a trial done in collaboration with Nofima all point to the conclusion that stimulation of the right type of host immunity by oestrogen is protective against lice. Manuscript is under way and the study will be presented at the conference in Vigo, Spain, this June.