Figure 2.—

Pedigree selection scheme for determining of persistence of heritable silencing. Young adult hermaphrodites of the strain oma-1(zu405), dpy-20(e1282ts)IV; him-5(e1467)V were injected with dsRNA trigger and allowed to recover at room temperature. Individual I₀ animals were plated onto petri dishes containing fresh lawns of OP-50 bacteria and grown at 23° for 3 days, when they were scored for viable progeny. Criteria for selecting animals to pedigree were (1) groups where all observed siblings had viable progeny and (2) from the sibling group, the individuals with largest brood sizes. Both these criteria were our indicators of a strong silencing response. We designated I₀'s (labeled “A1,” “B1,” and “C1”) and individually plated 14 F₁ animals from each. Three days later, we scored F₁ animals for viable progeny. We chose B1 as the best sibling group and picked plates B1.9, B1.11, and B1.14 as our source for L4 larvae (14 F₂ animals each). Three days later we scored F₂ for viable progeny. We chose B1.11 as the best sibling group, and plates B1.11.2, B1.11.5, and B1.11.11 as our source for L4 F₃ animals each. For F₄'s, we chose F₃ sibling group B1.11.2 and picked 14 animals from plates B1.11.2. 2, B1.11.2.7, and B1.11.2.13. We repeated this pedigree selection protocol using each of the two long dsRNA triggers, A1 and A2 (see Figure 1). For each generation and both triggers we scored 42 animals. We depict viability of progeny in sibling groups with a white background and inviability with a gray background. Solid circles represent plates selected at each generation to further pedigrees.