Aquaculture represents an essential resource for the present and future world population. However, fish and shellfish farming are constantly threatened by disease outbreaks. Functional feeds might represent a valuable alternative to improve fish natural defences. Minerals are a basic requirement for animals and at supranutritional levels they can be used as additives for inclusion in functional feeds. Among the essential elements, selenium (Se) is one of the most relevant, as fundamental component of diverse Se-containing proteins (selenoproteins). Several immunerelated processes rely on selenoproteins and Se supplementation can improve basal immune function. The diet is the most important Se source and its assimilation strongly depends on its concentration as well as its chemical speciation. The aim of this project was to determine if Sel-Plex® (a manufactured yeast based Se additive) supplementation of salmonid diets could elicit an immunostimulatory effect and improve the fish antiviral response. First, the most important selenoprotein families were characterized in rainbow trout (Oncorhynchus mykiss). The newly characterized genes showed a transcriptional modulation to Se exposure in vitro, therefore they were used to monitor the response in vivo to Sel-Plex® supplementation. Next, rainbow trout were fed different concentrations of Sel-Plex® (0, 0.5, 1 and 4 ppm) in a time course feeding trial. Combining chemical and bimolecular tolls, Se assimilation, metabolism and the effects of Sel-Plex® supplementation on selenoproteome expression in different tissues were investigated. The results showed that a concentration ranging between 0.5 to 4 ppm being fed for ten weeks was a suitable combination for further investigations. Rainbow trout were again fed diets enriched with 1 and 4 ppm Sel-Plex® for 10 weeks, and then injected with polyinosinic:polycytidylic acid (poly(I:C)). The analysis of their whole transcriptome response by microarray showed that several antiviral markers, especially the type-II interferon response, were boosted by 4 ppm Sel-Plex® supplementation. This work demonstrated that fish may require dietary levels of Se higher than the 0.5 ppm fixed by legislation and that they can benefit, especially during an immune challenge, from Sel-Plex® supplementation up to 4 ppm inclusion in the diet.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:646100 |
| Date | January 2014 |
| Creators | Pacitti, Davide |
| Publisher | University of Aberdeen |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=225763 |
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