crs encodes a conserved mitochondrial matrix chaperone, HSPA9B. (A) The crs mutation is on linkage group 14 (LG14) between the polymorphic microsatellite markers z43267 and z26376. The distance between crs and each polymorphic marker is shown in centimorgans on the left, and the number of recombinants of 2239 meioses is on the right. No recombinants were found on 2 PACs that contain the entire zebrafish hspa9b gene. (B) ABI automated sequencer-produced chromatographs from wild-type (top) and mutant (bottom) mRNA. A G>A point mutation produces a glycine-to-glutamate conversion at amino acid 492 in zebrafish HSPA9B. (C) Domain structure of HSPA9B. HSPA9B has an N-terminal adenosine triphosphatase domain (amino acids 55-434) immediately followed by a propeptide-binding domain (amino acids 435-587) within which the G492E mutation lies (red asterisk). Underneath the domain map is an alignment of the propeptide-binding domains of zebrafish and human HSPA9B and E coli. DnaK chaperones with conserved residues in gray and the conserved glycine mutated in crs zebrafish marked with a red asterisk. (D-E) Whole mount o-dianisidine staining of embryos injected with control (D) or hspa9b (E) morpholino-modified antisense oligonucleotides (MO) at 36 hpf.