Influence of Sample Storage on the Quality of DNA Extracted from Milk of Goats Fed Conventional or Transgenic Soybean
PCR approach was used in order to investigate the presence of plant DNA in pellet of somatic cells from fresh or stored milk of twenty grazing goats fed concentrate (18% CP; 1.03 UFL/kg, as fed) containing conventional or genetically modified soybean meal. The quantity and the purity of DNAs extracted from fresh samples were higher than those of samples stored at −20°C (ng/μl: 51.6 vs 20.8; A260/A280: 1.7 vs 1.4). The frequency of chloroplast sequence, for both groups, ranged between 70 and 100% in fresh and between 30 and 40% in stored samples. The frequency percentage of specific soybean gene was lower in stored (25–33%) than in fresh samples (56–88%). Transgenic fragments were found only in milk from goats fed GM soybean. For 35S promoter, the frequency was 38–75% in fresh and 25% in stored samples, while for CP4 EPSPS, it was 38–50% in fresh and 25% in stored samples.
KeywordsMilk Goat DNA extraction Transgene
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