Loss-of-function <i>nol9</i> mutation leads to a defect in ITS2 pre-rRNA processing.

<p>(A) Expression pattern of <i>nol9</i> by WISH at sphere stage (4 hpf), 12 hpf, 48 hpf, 72 hpf, 96 hpf and 120 hpf. Black arrows indicate branchial arches, white arrow indicates pancreas and arrowhead indicates <i>nol9</i>-expressing cells in the CHT. (B) Representative Northern blot analysis of RNA isolated from 5 dpf <i>nol9</i>^{<i>sa102/sa10222</i>} mutants and control (<i>nol9</i>^<i>+/+</i> and <i>nol9</i>^{<i>+/sa1022</i>}) siblings using 5’ETS, ITS1 and ITS2 probes to detect rRNA processing intermediates. Corresponding rRNA intermediates (a, b, c, d) are indicated in B) and C). (C) Schematic representation of the rRNA intermediates detected in the Northern blot analysis. The sites of hybridization of the 5’ETS, ITS1 and ITS2 probes are indicated in red. (D) Methylene blue staining of the membrane was used to control for equal loading of RNA. wt–<i>nol9</i>^<i>+/+</i>/<i>nol9</i>^{<i>+/sa1022</i>}, mut–<i>nol9</i>^{<i>sa1022/sa1022</i>}.