Figure 7

RNA quantity and integrity following immediate stabilization. (A) Relative RNA purity, defined as the ratio of absorbance at 260 and 280 nm, was determined by NanoDrop. A ratio of 2.0 is indicative of pure RNA. No significant differences were apparent across the treatment groups in any tissue. (B) RNA quantity was determined by NanoDrop. No significant differences were seen in relative RNA quantity in the brain regardless of treatment. In lung, when stabilization followed cryopreservation, RNA quantity increased when compared to samples immediately stabilized followed by cryopreservation (*p < 0.05, Kruskal-Wallis one way ANOVA on Ranks). In liver tissue, stabilization decreased total RNA quantity when compared to similar samples incubated at room temperature, 4°C, and immediately cryopreserved samples. (C) RNA quality, determined by relative amounts of degraded vs. intact RNA, was measured by Bioanalyzer and assigned an RNA integrity number (RIN). RINs range from 10 (intact) to 2 (degraded) with an average RIN being 7. While there were no statistically significant differences seen in lung tissue, in brain, RNA quality significantly decreased with immediate stabilization prior to cryopreservation compared to immediately cryopreserved samples. In liver, immediate stabilization significantly decreased RNA quality when compared to similar samples incubated at room temperature, 4°C, and immediately cryopreserved samples. Data are presented as mean ± S.E.M., n = 5-6/group brain and lung, n = 4/group liver (* p < 0.05, unpaired t-test). F - snap frozen; DF - Denator, snap freeze; FD - snap freeze, Denator; RT - room temperature; DRT - Denator, room temperature 2 hrs; 4°C - wet ice 2 hrs; D4°C - Denator, wet ice 2 hrs.