Fig. 2

The steif gene maps to a locus related to nematode unc-45. (A) the steif mutation was mapped to linkage group 8 (LG8) close to the marker fc15g07 and unc-45-related (now named unc-45b). (B) the point mutation in the unc-45b gene isolated from steif mutants changes a C to an A (arrow) leading to the formation of a stop codon. (C) in the steif mutant, the steif/unc-45b gene contains a point mutation that transforms the codon of cysteine 788 into a stop codon. The steif/unc-45b gene has the same domain structure as C. elegans unc-45 with N-terminal tricopeptide repeats (TPR), Central and the C-terminal UCS domain that is shared with the fungal proteins She4p and Cro1. The nonsense mutation in steif mutants leads to truncation of the UCS domain. (D–E) in situ hybridization to wild-type embryos showing steif/unc-45b mRNA localization in skeletal and cardiac muscles (arrow). (D) 24 hpf, lateral view; (E) 72 hpf, lateral view. am, adductor mandibulae; do, dilator operculi; hh, hyohyoideus; ih, interhyoideus; imp, intramandibular posterior; io, inferior oblique; ir, inferior rectus; lap, levator arcus palatini; lr, lateral rectus; so, superior oblique; tv, transversus ventralis. Arrow: heart. Scale bar: 120 μm (D); 60 μm (E).