title: Selenium Supplementation in Fish: A Combined Chemical and Biomolecular Study to Understand Sel-Plex Assimilation and Impact on Selenoproteome Expression in Rainbow Trout (Oncorhynchus mykiss).
abstract: BACKGROUND
  Selenium (Se) is an essential oligonutrient, as a component of several Se-containing proteins (selenoproteins), which exert important biological functions within an organism. In livestock, Se-enriched products have been proposed as dietary supplements to be included into functional feeds for animal preventive health care. To this end, it is important to understand the optimal range of concentrations for supplementation and how long it takes to be assimilated into the organism.
  
  
  METHODS
  In this study, rainbow trout (Oncorhynchus mykiss) were fed a control diet containing 0.9 g Kg-1 Se or the same diet supplemented with a Se-Yeast product (Sel-Plex) to achieve Se concentrations ranging from 1.5-8.9 g Kg-1 for a period of ten weeks. Fish were sampled every two weeks for analysis. The kinetics of Se bioaccumulation and the effects on fish selenoprotein expression was determined in different tissues combining chemical and bimolecular techniques.
  
  
  RESULTS
  The Sel-Plex enriched diets did not have any effect on survival and growth performance. The highest Se levels were found in liver and kidney followed by muscle and blood cells. Analysis of the Se concentration factor showed that liver is able to initially regulate the amount of Se accumulated. However, with higher dietary Se level (4.8 and 8.9 g Kg-1) and longer times of exposure (10 weeks), regulation is ineffective and the Se tissue concentration increases. The expression of the selected trout selenoprotein transcripts showed an inverse correlation with Sel-Plex augmentation in most cases. In liver, kidney and blood cells the highest up-regulation of the trout selenoprotein genes was seen mostly in the group fed the diet enriched with the lowest concentration of Sel-Plex (0.5 g Kg-1) for 10 weeks.
  
  
  CONCLUSIONS
  Sel-Plex may represent an excellent Se supplement to deliver a high level of Se without provoking harm to the fish and to guarantee the maximal absorption of the element. According to our results, a dietary supplementation of Sel-Plex between 0.5 and 4 g Kg-1 may allow maximal benefits, whereas 8 g Kg-1 may be excessive for the purpose of supplementation.
authors.affiliation: Scottish Fish Immunology Research Centre, Institute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen, United Kingdom.
authors.forename: Davide
authors.initials: D
authors.lastname: Pacitti
authors.affiliation: Trace Element Speciation Laboratory, Department of Chemistry, University of Aberdeen, Aberdeen, United Kingdom.
authors.forename: Muhammad M
authors.initials: MM
authors.lastname: Lawan
authors.affiliation: Alltech Biosciences Centre, Sarney, Summerhill Rd, Dunboyne, Country Meath, Ireland.
authors.forename: John
authors.initials: J
authors.lastname: Sweetman
authors.affiliation: Scottish Fish Immunology Research Centre, Institute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen, United Kingdom.
authors.forename: Samuel A M
authors.initials: SA
authors.lastname: Martin
authors.affiliation: Trace Element Speciation Laboratory, Department of Chemistry, University of Aberdeen, Aberdeen, United Kingdom.
authors.forename: Jörg
authors.initials: J
authors.lastname: Feldmann
authors.affiliation: Scottish Fish Immunology Research Centre, Institute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen, United Kingdom.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Secombes
mesh_terms: D000821:Animal Feed; D000818:Animals; D019587:Dietary Supplements; D004305:Dose-Response Relationship, Drug; D007668:Kidney / Q000737:chemistry; D008099:Liver / Q000737:chemistry; D017686:Oncorhynchus mykiss / Q000254:growth & development / Q000378:metabolism*; D020543:Proteome / Q000187:drug effects; D018036:Selenium Compounds / Q000008:administration & dosage / Q000032:analysis / Q000494:pharmacology*
chemical_list: D020543:Proteome; D018036:Selenium Compounds