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. 2014 Jul 17;9(7):e102826. doi: 10.1371/journal.pone.0102826

Figure 3. Phosphate gradient test.

Figure 3

(A) 1° extract. 1.2% agarose gel using 0.1 µg/ml ethidium bromide in 1×TAE at 3 V/cm for 90 min. Lanes 1–6 (1° extract); 0, 100 mM PB, 200 mM PB, 300 mM PB, 400 mM PB, and 500 mM PB in the lysis reagent respectively. Ten percent of the total yield from the initial extraction process from 200 mg wet weight of the iron oxide cemented clay environment electrophoresed in each lane. 1 M PB Wash. Lanes 1–6 show the results of a re-wash of the sedimented clay pellets from the 1° extraction process with 1 M sodium phosphate buffer (pH 7.2). Ten percent of the total yield from the 1 M PB clay pellet re-wash was electrophoresed. Lane M; Marker III (Roche). (B) Second of three replicate extraction sets electrophoresed as given for (A) showing the extent of set to set variability. (C) 1.2% agarose gel using 0.1 µg/ml ethidium bromide in 1×TAE at 4.7 V/cm for 90 min. Lanes 1–3; replicate extractions from 250 mg samples of the iron oxide cemented clay using the Powerlyzer, PowerSoil® DNA isolation kit (MoBio); 10% of the total yield. Lane M; Marker III (Roche).