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-g 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.Key words: Cry1Ab: GM plants: Safety: Soyabean meal GM maize is one of the major GM crops grown worldwide. In comparison to 2010, the field area of GM maize planted increased by 11 % to just under 51 million hectares in 2011, occupying 32 % of the total global maize cultivation area (1) .It is becoming increasingly difficult to obtain non-GM maize. Various maize products are used in commercial diets for farmed fishes. The carbohydrate in whole-kernel meal is an energy source and the starch serves as a feed binder. As a result of the increasing production of salmon and other fish species and decreasing availability of fishmeal, which has been the main dietary protein source, especially for piscivorous fish, plant protein sources are increasingly being used in diets to obtain a cost-efficient, sustainable aquaculture industry. Maize gluten meal, a by-product of starch extraction containing approximately 60 % protein, has increased in importance as a protein source in fish feeds. The wet-milling process used to extract starch and provide maize gluten meal as a by-product is carried out by steeping the maize kernels in water at 508C, mildly acidified with sulphur dioxide (0·01 %) to prevent microbial growth, with subsequent grinding and mechani...

Effects of dietary soy saponins and phytosterols on gilthead sea bream (Sparus aurata) during the on-growing period

“…Down regulation of PepT1 (solute carrier family 15 member 1) has been reported previously in salmon fed diets with soybean meal (Gu et al, 2013a) or pea protein concentrate and saponins (Kortner et al, 2012), and in both studies, fish presented marked intestinal inflammation. Such observations were associated with the apparent functional loss, which accompanies the inflammatory response.…”

Curcumin boosts DHA in the brain: Implications for the prevention of anxiety disorders

“…For example, aquaculture currently accounts for nearly one half of the seafood supply for human consumption in the world, which is large increase compared with 1980’s, where aquaculture contributed only 9% or even 2000 where fisheries made up 34% [68]. Terrestrial oilseeds [69] and maize [70] are commercially used in fish feed, which can increase the ratio of n-6:n-3 in seafood [71–74]. Other dietary sources of DHA, such as beef [75] and eggs [76] have reduced DHA content when using the most prevalent farming practices of grain corn feeding vs pasture-feeding.…”

Chronic Responses ofDaphnia magnaUnder Dietary Exposure to Leaves of a Transgenic (Event MON810) Bt–Maize Hybrid and its Conventional Near-Isoline

“…In contrast, negative nontarget effects of Bt-maize were found in certain cases, particularly for aquatic organisms, such as Trichoptera larvae fed Bt-maize leaves (Rosi-Marshall et al, 2007;Chambers et al, 2010), and Daphnia magna fed ground Bt-maize kernels (Bøhn et al, 2008(Bøhn et al, , 2010. Significant effects of MON810 maize were recently noted in salmon (Salmo salar) (Gu et al 2013(Gu et al , 2014, but were considered to be of minor biological significance because the overall development and health of the animals was not affected. Nontarget effects of other Bt-plants (Populus spp.)…”