alnz24 is a null mutation that regulates NC formation and encodes RNA polymerase II-associated factor 1 (Paf1). (A-E) 36 hpf wild-type and aln mutant embryos. Wild-type embryos (A) have pigmented melanophores lacking in embryos harboring combinations of aln mutant alleles: (B) homozygous for the alnz12 deletion mutation, (C) transheterozygous for the alnz12 and c4 deletions, (D) transheterozygous for the alnz12 deletion and alnz24 ENU-induced mutations, and (E) homozygous for the alnz24 mutation. (F,G) crestin expression detected by whole-mount in situ hybridization in 24 hpf wild-type sibling (F) and alnz24 mutant (G) embryos, indicating a complete absence of migrating trunk NC in alnz24. Arrowheads indicate premigratory and migrating trunk NC. A-G are lateral views with anterior to the left. (H) Paf1 protein is not detected by immunoblot analysis in 36 hpf alnz12 or alnz24 mutant embryos, but is readily detected in wild-type control siblings. Immunoblot detection of pMAPK serves as a protein-loading control.