Figure 1

Southern analysis of restriction endonuclease-digested Euglena DNA demonstrating multiple bands hybridizing with a U3 snoRNA gene probe. (A) Euglena DNA was digested with Bam H1 (B), Eco R1 (E) or with both (B/E) endonucleases, two restriction enzymes that do not have recognition sequences within the Euglena U3 snoRNA gene. Restriction fragments were resolved by electrophoresis prior to Southern transfer and hybridization with a Euglena U3 snoRNA probe, all as described in Methods. The exact number of hybridizing fragments in the 10 to 38.5 kbp size range is difficult to determine owing to the limited resolution of this size range on standard agarose gels. (MW; a mixture of Invitrogen™ λ DNA/Hin dIII, 1 Kb Plus and λ DNA/High Molecular Weight Markers) (B) Densitometric analysis confirms that the multiple hybridizing bands display unequal hybridization signal intensities. Euglena DNA, digested with Eco R1 (E), was resolved by electrophoresis in a 0.7% agarose/1× TAE gel prior to Southern transfer and hybridization. The results of densitometric analysis using ImageJ [97] are shown to the right of the sample lane, with peak areas corresponding to the relative signal intensities of the labeled bands. For the indicated bands, the first number gives the area under the peak while the second number represents signal intensity normalized to that of the 2.5-kbp band (signal intensity 1425, the lowest in the lane).