SpREJ transcript levels in six adult tissues. Transcript copy numbers per 100 ng of total RNA from each tissue was first calculated for all SpREJs. Transcript copy numbers were calculated from a standard curve generated in the same run and were normalized to the level of ubiquitin transcripts. It should be noted that the constancy of ubiquitin transcripts in adult tissues has not been determined. Final copy numbers were taken as the averages of duplicates. T, testis; O, ovary; M/T, muscle/test of body wall; G, gut; L, lantern (jaws, ligaments and muscles); C, coelomocytes (immunocytes).