title: Effects of oral Bt-maize (MON810) exposure on growth and health parameters in normal and sensitised Atlantic salmon, Salmo salar L.
abstract: Responses to GM maize Bt-maize, MON810) expressing Cry1Ab protein from the soil bacterium Bacillus thuringiensis (Bt) in diets for both normal and immune-sensitised (with soyabean meal (SBM)-induced enteropathy) post-smolt Atlantic salmon were investigated following 33 and 97 d of exposure. Triplicate tanks of salmon were fed one of four diets, all containing 20% whole-kernel meal maize, either Bt-maize or its near-isogenic maternal line, without or with 15% extracted SBM inclusion. The fish fed Bt-maize utilised the feed less efficiently, as revealed by lower protein and mineral digestibilities and lower lipid and energy retention efficiencies. Higher intestinal weight, as well as increased interferon-γ and decreased sodium-glucose co-transporter mRNA expression, and a transient increase in T-helper cell presence, as measured by cluster of differentiation 4 (CD4) protein in the distal intestine (DI), may partly explain the lower nutrient digestibilities and retentions. The Bt-maize seemed to potentiate oxidative cellular stress in the DI of immune-sensitised fish, as indicated by increases in superoxide dismutase and heat shock protein 70 mRNA expression. The data suggest that Cry1Ab protein or other antigens in Bt-maize have local immunogenic effects in salmon DI. No systemic immune responses could be detected, as indicated by haematology, differential leucocyte counts, plasma clinical chemistry, as well as absence of Cry1Ab-specific antibodies and Cry1Ab protein in plasma. The responses to Bt-maize observed in the present study differed from results from earlier studies in salmon and other animals fed the same event Bt-maize. Longer-term experiments and more in-depth studies on intestinal physiology and immune responses are needed to evaluate health implications.
authors.affiliation: Department of Basic Sciences and Aquatic Medicine, Norwegian School of Veterinary Science, Aquaculture Protein Centre, PO Box 8146 Dep., N-0033, Oslo, Norway.
authors.forename: Jinni
authors.initials: J
authors.lastname: Gu
authors.forename: Åshild
authors.initials: Å
authors.lastname: Krogdahl
authors.forename: Nini H
authors.initials: NH
authors.lastname: Sissener
authors.forename: Trond M
authors.initials: TM
authors.lastname: Kortner
authors.forename: Eva
authors.initials: E
authors.lastname: Gelencser
authors.forename: Gro-Ingunn
authors.initials: GI
authors.lastname: Hemre
authors.forename: Anne Marie
authors.initials: AM
authors.lastname: Bakke
mesh_terms: D000704:Analysis of Variance; D000821:Animal Feed / Q000009:adverse effects / Q000382:microbiology; D000818:Animals; D001413:Bacillus thuringiensis / Q000235:genetics; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000097:blood*; D004731:Endotoxins / Q000097:blood*; D004797:Enzyme-Linked Immunosorbent Assay; D030841:Food, Genetically Modified / Q000009:adverse effects*; D006460:Hemolysin Proteins / Q000097:blood*; D007422:Intestines / Q000166:cytology* / Q000201:enzymology / Q000276:immunology; D008099:Liver / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000009:adverse effects*; D060888:Real-Time Polymerase Chain Reaction; D020317:Salmo salar / Q000254:growth & development* / Q000276:immunology / Q000378:metabolism; D013025:Glycine max; D003313:Zea mays / Q000235:genetics* / Q000382:microbiology
chemical_list: D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D004731:Endotoxins; D006460:Hemolysin Proteins; C030956:insecticidal crystal protein, Bacillus Thuringiensis