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. 2010 Aug;19(4):683-9.
doi: 10.1007/s11248-009-9339-z. Epub 2009 Nov 4.

Degradation of Cry1Ab Protein From Genetically Modified Maize (MON810) in Relation to Total Dietary Feed Proteins in Dairy Cow Digestion

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Free PMC article

Degradation of Cry1Ab Protein From Genetically Modified Maize (MON810) in Relation to Total Dietary Feed Proteins in Dairy Cow Digestion

Vijay Paul et al. Transgenic Res. .
Free PMC article

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 mug/g of total proteins) was recorded. Concentrations of Cry1Ab protein in GIT digesta of cows fed T diets varied between the lowest 0.38 mug/g of total proteins in abomasum to the highest 3.84 mug/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.

Figures

Fig. 1
Fig. 1
Concentration of Cry1Ab protein in feed (pTMR) and feces of dairy cows fed partial total mixed rations containing either transgenic maize or non-transgenic maize. Panel, a represents Cry1Ab protein μg/g total protein, and b represents Cry1Ab protein ng/g wet sample, respectively asterisks indicates (P < 0.01)
Fig. 2
Fig. 2
Relative Cry1Ab protein concentrations in different GIT digesta for cows fed a partial total mixed ration diets containing either transgenic or non-transgenic maize. Panel, a represents Cry1Ab protein μg/g total protein, and b represents Cry1Ab protein ng/g digesta, respectively. Concentrations of Cry1Ab protein in non-transgenic diet fed digesta were below the assay decision limit (CCα) value of 1.21 ng/g wet weight
Fig. 3
Fig. 3
Relative total protein concentrations in different GIT digesta for cows fed a partial total mixed ration containing either transgenic or non-transgenic maize
Fig. 4
Fig. 4
Western blot showing fragments of Cry1Ab protein in total protein extracts (60 μg) of transgenic and non-transgenic diet ingredients (K, kernels; CO, cobs; S, silage; MR, partial total mixed ration). Trypsin treated and HPLC purified Cry1Ab protein (100 pg) was included as a positive control (C)
Fig. 5
Fig. 5
Western blot showing fragments of Cry1Ab protein in GIT digesta (Ru, rumen; LI, large intestine; Ce, cecum) extracts from transgenic and non-transgenic diets (MR) fed cows. Trypsin treated and HPLC purified Cry1Ab protein (100 pg) was included as a positive control (C). Each extract except rumen content contained 100 pg Cry1Ab protein (as measured in ELISA), whereas due to low concentration of Cry1Ab protein in rumen content extract 70 pg Cry1Ab protein was used. In non-transgenic feed and digesta extract respective amount of total protein was used
Fig. 6
Fig. 6
Western blot showing Cry1Ab protein fragments in total protein extracts (60 μg) of transgenic (T) and non-transgenic feed (NT) and respective transgenic (T1, T2, T3) and non-transgenic (NT1, NT2, NT3) ration fed feces of dairy cows. Trypsin treated and HPLC purified Cry1Ab protein (100 pg) was used as a positive control (C)

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