FIGURE 3.

Example electropherograms of contaminated versus clean (sequencing-quality) cDNA samples generated from single neurons. (A) Samples with high cDNA yields are typically characterized by distinctive features of the cDNA fragment profile indicative of contamination: multiple sharp peaks (top figure) or an early rising peak with increased cDNA amount at lower base-pair sizes and a “jagged” pattern (middle and bottom). (B) Samples generating good-quality sequencing data have a shallow peak with a maximum at ∼2,000 bp (range ∼400–9,000 bp, specific region), no jaggedness, and no cDNA product at lower base pair size (non-specific region). Addition of ERCC RNA spike-in controls to the sample collection buffer may result in the appearance of additional peaks (indicated by asterisks).