Fig. 6. The distribution of cuticular segmentation defects for different concentrations of dsRNA (A-D) and morpholino oligos (E) are shown. Given is the absolute number of cuticles that lacked a certain number of segments. Only individuals that had been injected with an effective dose of dsRNA/morpholino were counted (as judged by the presence of anterior transformations). The dsRNA concentrations ranged within several orders of magnitude (2000 ng/µl in A to 7.5 ng/µl in D). Nevertheless, the observed dose effect was relatively mild (compare A through D). The proportion of injected embryos that developed cuticles decreased with dsRNA concentration: 20% with 2000 and 750 versus 50% with 75 and 7.5 ng/µl, respectively. Additionally, the proportion of cuticles that produced a phenotype increased with higher concentrations of dsRNA: 75% with 2000 and 750 versus 50% with 75 and 7.5 ng/µl, respectively. Injection of low amounts of the lowest concentration resulted in 80% wild-type cuticles, suggesting that the minimal requirement for dsRNA was approached with 7.5 ng/µl. (E) Although morpholino oligos inhibit gene function by a different mechanism and are chemically distinct, a similar range of deletions was observed.