Tried another method of RNA Isolation for comparison with regular TriReagent method.
Used the Direct-zol RNA MiniPrep Kit (Zymo Research) on the following samples stored in RNAlater:
- P6 Control
- P16 Filt. Inj.
Pelleted samples in RNAlater by spinning 5000g, 10mins @ RT. Removed RNAlater, lysed pellets in 1mL TriReagent. Split each sample equally into two tubes (500uL in each tube). Added equal volumes of 100% ethanol to each tube and vortexed. Transferred samples to spin columns and followe manufacturer’s protocol. Eluted with 25uL of nuclease-free H2O (provided in kit). Spec’d on NanoDrop1000.
RNA quality is very good (based on 260/280 ratios). This turned out much better than the previous attmpt using the basic TriReagent method. However, the previous attempt (see 20140401) may have been compromised by me being too aggressive when collecting the aqueous phase. Knowing how little sample was present, I may have been overzealous in trying to gather too much of the aqueous phase, leading to the phenol carryover that was evident.
Regardless, these columns seem to do an excellent job of eliminating even salt carryover, as we frequently see high absorbance at 230nm with marine samples; particularly those stored in RNAlater.