Evaluation of stress‐ and immune‐response biomarkers in Atlantic salmon, Salmo salar L., fed different levels of genetically modified maize (Bt maize), compared with its near‐isogenic parental line and a commercial suprex maize

Abstract

The present study was designed to evaluate if genetically modified (GM) maize (Bt maize, event MON810) compared with the near-isogenic nonmodified (nGM) maize variety, added as a starch source at low or high inclusions, affected fish health of post-smolt Atlantic salmon, Salmo salar L. To evaluate the health impact, selected stress-and immune-response biomarkers were quantified at the gene transcript (mRNA) level, and some also at the protein level. The diets with low or high inclusions of GM maize, and its near-isogenic nGM parental line, were compared to a control diet containing GM-free suprex maize (reference diet) as the only starch source. Total superoxide dismutase (SOD) activity in liver and distal intestine was significantly higher in fish fed GM maize compared with fish fed nGM maize and with the reference diet group. Fish fed GM maize showed significantly lower catalase (CAT) activity in liver compared with fish fed nGM maize and to the reference diet group. In contrast, CAT activity in distal intestine was significantly higher for fish fed GM maize compared with fish fed reference diet. Protein level of heat shock protein 70 (HSP70) in liver was significantly higher in fish fed GM maize compared with fish fed the reference diet. No diet-related differences were found in normalized gene expression of SOD, CAT or HSP70 in liver or distal intestine. Normalized gene expression of interleukin-1 beta in spleen and head-kidney did not vary significantly between diet groups. Interestingly, fish fed high GM maize showed a significantly larger proportion of plasma granulocytes, a significantly larger sum of plasma granulocyte and monocyte proportions, but a significantly smaller proportion of plasma lymphocytes, compared with fish fed high nGM maize. In conclusion, Atlantic salmon fed GM maize showed some small changes in stress protein levels and activities, but none of these changes were comparable to the normalized gene expression levels analysed for these stress proteins. GM maize seemed to induce significant changes in white blood cell populations which are associated with an immune response.

Defatted Biomass of the Microalga, Desmodesmus sp., Can Replace Fishmeal in the Feeds for Atlantic salmon

“…One of the antinutritional factors, β-conglycinin was found to decrease the antioxidant capacity indices such as SOD, CAT, glutathione-S-transferase, glutathione peroxidase and glutathione reductase activities and glutathione content in the intestine and enterocytes of juvenile Jian carp (Cyprinus carpio) . Furthermore, feeding Atlantic salmon with genetically modified maize is reported to elevate the SOD and CAT activity in the distal intestine of the fish (Sagstad et al, 2007). However, based on the results of the present study, Desmodesmus-feeding did not significantly alter the serum antioxidant indices (TAC, SOD and CAT) and the associated genes (sod1, nrf2) in the intestine of alga-fed groups.…”

Effects of Cortisol on the Intestinal Mucosal Immune Response during Cohabitant Challenge with IPNV in Atlantic Salmon (Salmo salar)

“…Therefore, a second reference gene, 18S rRNA, was tested. This reference gene has previously been shown to be stable in the intestine during viral challenge experiments [39] and proposed to be a good reference gene in tissues with high cell turnover [40], [41]. However, also the 18S gene showed a lower expression level in the distal intestine of the +IPNV+F group.…”

Dietary carbohydrate/lipid ratios affect stress, oxidative status and non-specific immune responses of fingerling blunt snout bream, Megalobrama amblycephala

“…However, most research focused mainly on the stressors unrelated to diet manipulation, including capture, handling, crowding, confinement, transporting, hypoxia, infection, vaccination, temperature and chemical exposure, to list a few [42,43]. The correlations between diet composition and fish stress and immune responses have while received little attention [1,3,16,21,22,27]. In the present study, six isonitrogenous and isoenergetic diets with different CHO:L ratios were formulated to evaluate the capability of a herbivorous freshwater carp M. amblycephala to utilize dietary carbohydrate and lipid for energy, with special emphasize on its physiological responses.…”