Fig. 1. Pigment, cartilage and aortic arch defects in low^ts213 mutant zebrafish. Living wild-type and low mutant embryos. Lateral views (A-C) showing melanocyte reduction at 28 hpf (note normal eye pigmentation in low) and jaw defect at 72 hpf (C). (D-G) Dissected pharyngeal cartilages from 4 dpf wild-type (D,F) and low mutant (E,G) larvae, stained with Alcian Blue and shown in ventral (D,E) and lateral (F,G) view. (E,G) Branchial cartilages have been torn away. (H,I) Camera lucida drawings of mandibular and hyoid cartilages in wild type (F) and low mutant (G). Pharyngeal cartilages and joints (arrows) are absent or reduced in all but the mandibular arch in low mutants, which fuses with the anterior basicranial commissure of the skull. (J,K) Aortic arches in 4 dpf wild-type (J) and low mutant (K) larvae, labeled with fluorescent microspheres and shown in ventrolateral view. (L) Camera lucida drawings of aortic arches in wild-type (left) and defects in low mutants (right). abc, anterior basicranial commissure; cb1-5, ceratobranchials 1-5; ch, ceratohyal; e, eye; hs, hyosymplectic; ih, interhyal; m, Meckel's; op, opercular bone; pc, parachordals; pq, palatoquadrate; t, trabeculae. Scale bars: 100 µm.