Degradation of Cry1Ab protein from genetically modified maize (MON810) in relation to total dietary feed proteins in dairy cow digestion

Abstract

To investigate the relative degradation and fragmentation pattern of the recombinant Cry1Ab protein from genetically modified (GM) maize MON810 throughout the gastrointestinal tract (GIT) of dairy cows, a 25 months GM maize feeding study was conducted on 36 lactating Bavarian Fleckvieh cows allocated into two groups (18 cows per group) fed diets containing either GM maize MON810 or nearly isogenic non-GM maize as the respective diet components. All cows were fed a partial total mixed ration (pTMR). During the feeding trial, 8 feed (4 transgenic (T) and 4 non-transgenic (NT) pTMR) and 42 feces (26 T and 18 NT) samples from the subset of cows fed T and NT diets, and at the end of the feeding trial, digesta contents of rumen, abomasum, small intestine, large intestine and cecum were collected after the slaughter of six cows of each feeding group. Samples were analyzed for Cry1Ab protein and total protein using Cry1Ab specific ELISA and bicinchoninic acid assay, respectively. Immunoblot analyses were performed to evaluate the integrity of Cry1Ab protein in feed, digesta and feces samples. A decrease to 44% in Cry1Ab protein concentration from T pTMR to the voided feces (9.40 versus 4.18 μg/g of total proteins) was recorded. Concentrations of Cry1Ab protein in GIT digesta of cows fed T diets varied between the lowest 0.38 μg/g of total proteins in abomasum to the highest 3.84 μg/g of total proteins in rumen. Immunoblot analysis revealed the extensive degradation of recombinant Cry1Ab protein into a smaller fragment of around 34 kDa in GIT. The results of the present study indicate that the recombinant Cry1Ab protein from MON810 is increasingly degraded into a small fragment during dairy cow digestion.

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

“…Other investigators also found immunoreactive rCry1Ab proteins (or protein fragments) of several sizes in MON810 Bt-maize, including a 34-kD protein (Paul et al, 2010;Grubber et al, 2011). Further, the 34-kD protein apparently has greater stability to proteolysis, which might be relevant for potential effects of GM maize in agroecosystems (Paul et al, 2010). To our knowledge, these peptides have not yet been specifically tested for toxicity to nontarget organisms.…”

The effect of genetically modified feeds on productivity, milk composition, serum metabolite profiles and transfer of tDNA into milk of cows

“…After feed intake, both the DNA and protein are further degraded within the bovine gastrointestinal tract Wiedemann et al, 2006). Paul et al (2010) reported that the Cry1Ab protein from MON810 is increasingly degraded during digestion in the dairy cow gastrointestinal tract via small fragments, and in comparison with total protein in feed, the relative amount of CrylAb protein in faeces is markedly reduced, indicating that CrylAb protein is not more stable than other proteins in the feed.…”

Scientific Opinion on application EFSA‐GMO‐BE‐2013‐117 for authorisation of genetically modified maize MON 87427 × MON 89034 × NK603 and subcombinations independently of their origin, for food and feed uses, import and processing submitted under Regulation (EC) No 1829/2003 by Monsanto Company

“…Cry proteins are degraded by enzymatic activity in the gastrointestinal tract, meaning that only low amounts of intact Cry proteins would remain in the faeces. This was demonstrated for Cry1Ab (Einspanier et al, 2004;Lutz et al, 2005;Lutz et al, 2006;Wiedemann et al, 2006;Guertler et al, 2008;Paul et al, 2010). Further degradation of the protein in manure and faeces will take place because of microbiological proteolytic activity.…”