Assignment of “quality score” to sscDNA probes.

<p>Quality scores of 1–4 for sscDNA were assigned following visual assessment of distribution of polynucleotide size, with representative electropherograms shown here. (<b>A</b>) sscDNA synthesised from 50 ng total HUVEC RNA represents an amplification positive control of highest quality achievable. (<b>B</b>) sscDNA synthesised from 300 pg total HUVEC RNA amplification positive control of highest quality that could be expected from 300 pg of input RNA. (<b>C–G</b>) sscDNA synthesised from 300 pg of total RNA from a vascular endothelial biopsy sample. sscDNA has a electropherogram similar to that seen in the positive controls, peaking at over 500 nts and so was attributed a cDNA quality of 1 (C). sscDNAs progressively shorter in size distribution were designated quality scores of 2, 3 or 4 (D–G). sscDNAs designated lowest quality and therefore not hybridised to GeneChips (C) were of predominantly <200 nts in length. (<b>H</b>) No template control (NTC).