Fig. 3. Northern blot hybridization of clone LL_MET against total RNA (15 µg per lane) isolated from foot muscle (A) or hepatopancreas (B) of L. littorea showing changes in transcript levels over a time course of freezing or anoxia stress. Samples were collected from control (C, untreated), stressed (1, 12 or 24 h of anoxia or freezing exposure) and 24 h recovered (after 6 days of stress exposure) snails. Representative northern blots (top) are shown with the corresponding ethidium bromide-stained ribosomal RNA bands (middle) from the formaldehyde gel. Histograms (bottom) show normalized band intensities. Values are means ± S.E.M. for N=3 independent trials using RNA isolated from different individuals. Measured pixel densities for each band were first normalized against their corresponding rRNA band and then mean band intensity was calculated for each treatment. Finally, experimental values were plotted relative to the corresponding control value that was set to 1. Asterisks indicate values that differ significantly from controls, Student's t-test (P<0.05).