Fig. 5. Northern blot analysis of crayfish heart SERCA mRNA in heart muscle during different stages of the moulting cycle. (Top) Heart muscle total RNA (5 µg) from 18 crayfish at different moult stages was used: intermoult (N=6), late premoult (N=6) and postmoult (1-2 days, N=6). The membrane was hybridized to a heart-specific SERCA probe (723 bp) and exposed to X-ray film for 24h. (Bottom) 18S RNA concentration on the corresponding formaldehyde/agarose gel before being transferred to the membrane to serve as control (visualized by Ethidium Bromide staining).