Effect of age of slides and dissectates, and proteinase K treatment duration on RNA yield. A. Total RNA and miR-16 yields from laser microdissectates from three tissues prepared from four or seven day-old slides relative to zero or three day-old ones, respectively. B. Total RNA yield from identical laser dissectates from zero day-old slides stored in duplicate at room temperature (RT), or at -80°C with or without buffer (buff.) for a day. C. Total RNA yield (filled circles) and levels of RNU6-2 (black empty circles) and miR-16 (grey empty circles) from identical dissectates treated in triplicate with proteinase K (prot. K) for 0.5, 3 or 20 h. Means and their standard errors are plotted. Log2-transformed RNU6-2 and miR-16 levels were determined from quantification cycle (C
) values obtained in reverse transcription-PCR assays. Total RNA was quantified by RiboGreen assay. Hematoxylin and eosin was used as the histologic stain, and silicon carbide columns were used for RNA isolation.