title: Dietary phytochemicals modulate skin gene expression profiles and result in reduced lice counts after experimental infection in Atlantic salmon.
abstract: The use of phytochemicals is a promising solution in biological control against salmon louse (Lepeophtheirus salmonis). Glucosinolates belong to a diverse group of compounds used as protection against herbivores by plants in the family Brassicaceae, while in vertebrates, ingested glucosinolates exert health-promoting effects due to their antioxidant and detoxifying properties as well as effects on cell proliferation and growth. The aim of this study was to investigate if Atlantic salmon fed two different doses of glucosinolate-enriched feeds would be protected against lice infection. The effects of feeding high dose of glucosinolates before the infection, and of high and low doses five weeks into the infection were studied.
  
  
  
  Skin was screened by 15 k oligonucleotide microarray and qPCR.
  
  
  
  A 25 % reduction (P < 0.05) in lice counts was obtained in the low dose group and a 17 % reduction in the high dose group compared to fish fed control feed. Microarray analysis revealed induction of over 50 interferon (IFN)-related genes prior to lice infection. Genes upregulated five weeks into the infection in glucosinolate-enriched dietary groups included Type 1 pro-inflammatory factors, antimicrobial and acute phase proteins, extracellular matrix remodeling proteases and iron homeostasis regulators. In contrast, genes involved in muscle contraction, lipid and glucose metabolism were found more highly expressed in the skin of infected control fish.
  
  
  
  Atlantic salmon fed glucosinolates had a significantly lower number of sea lice at the end of the experimental challenge. Feeding glucosinolates coincided with increased expression of IFN-related genes, and higher expression profiles of Type 1 immune genes late into the infection. In addition, regulation of genes involved in the metabolism of iron, lipid and sugar suggested an interplay between metabolism of nutrients and mechanisms of resistance.
authors.affiliation: Faculty of Veterinary Medicine and Biosciences, Sea Lice Research Centre, Norwegian University of Life Sciences, PO Box 8146 Dep, 0033, Oslo, Norway.
authors.forename: Helle
authors.initials: H
authors.lastname: Jodaa Holm
authors.affiliation: Sea Lice Research Centre, EWOS Innovation, Dirdal, Norway.
authors.forename: Simon
authors.initials: S
authors.lastname: Wadsworth
authors.affiliation: Sea Lice Research Centre, EWOS Innovation, Dirdal, Norway.
authors.forename: Anne-Kari
authors.initials: AK
authors.lastname: Bjelland
authors.affiliation: Nofima AS, Osloveien 1, Ås, Norway.
authors.forename: Aleksei
authors.initials: A
authors.lastname: Krasnov
authors.affiliation: Faculty of Veterinary Medicine and Biosciences, Sea Lice Research Centre, Norwegian University of Life Sciences, PO Box 8146 Dep, 0033, Oslo, Norway.
authors.forename: Øystein
authors.initials: Ø
authors.lastname: Evensen
authors.affiliation: Faculty of Veterinary Medicine and Biosciences, Sea Lice Research Centre, Norwegian University of Life Sciences, PO Box 8146 Dep, 0033, Oslo, Norway. Stanko.Skugor@nmbu.no.
authors.forename: Stanko
authors.initials: S
authors.lastname: Skugor
mesh_terms: D000818:Animals; D033342:Copepoda / Q000254:growth & development*; D004478:Ectoparasitic Infestations / Q000469:parasitology / Q000517:prevention & control / Q000662:veterinary*; D005260:Female; D005393:Fish Diseases / Q000469:parasitology / Q000517:prevention & control*; D020869:Gene Expression Profiling / Q000662:veterinary; D005786:Gene Expression Regulation / Q000187:drug effects; D005961:Glucosinolates / Q000008:administration & dosage*; D008297:Male; D020411:Oligonucleotide Array Sequence Analysis / Q000662:veterinary; D064209:Phytochemicals / Q000008:administration & dosage*; D020317:Salmo salar / Q000469:parasitology*; D012867:Skin / Q000469:parasitology / Q000473:pathology; D059467:Transcriptome / Q000187:drug effects
chemical_list: D005961:Glucosinolates; D064209:Phytochemicals
keywords: Anti-attachment feed; Atlantic salmon; Glucosinolates; Salmo salar; Sea lice