Beware of Fixation—It Might Affect Your Experiments

Because of difficulties during the fixation in space and the often reported enhanced expression of stress-related genes in space experiments, we investigated the possible effect of fixation on gene expression. Comparing two fixatives (RNAlater^® and 70% ethanol), two-day-old Brassica rapa seedlings were either fixed by gradual exposure or immediate and complete immersion in fixative for two days. Neither fixative yielded high amounts of rRNA; RNAlater^® resulted in higher RNA yield in shoot tissue but qPCR data showed higher yield in ethanol-fixed material. qPCR analyses showed strongly enhanced transcripts of stress-related genes, especially in RNAlater^®-fixed material. The data suggest that fixation artefacts may be partially responsible for effects commonly attributed to space syndromes.