Figure 3.

The vu57 allele is a mutation of hmgcs1. A, Amino acid sequences of the conserved homodimerization domain of Hmgcs1 proteins (gray text). The vu57 allele changes a histidine to glutamine within the homodimerization domain. B–E, Lateral views, with dorsal up, of trunk spinal cords of living 3 dpf larvae. Dorsally migrated OPCs (arrows) occupy positions close to the DLF (dotted line) of wild-type (B). OPCs migrate past the DLF in vu57 mutant larva (C) and vu57 mutant larva injected with mutant hmgcs1 RNA (D) but are close to the DLF in mutant larvae injected with wild-type hmgcs1 RNA (E). F–M, Images of hindbrains viewed from dorsal with anterior to the left, of larvae processed for in situ RNA hybridization. Wild-type larva expresses plp1a (F), whereas a vu57 mutant larva (G) and a vu57 mutant larva injected with mutant hmgcs1 (H) express plp1a only at very low levels. By contrast, a vu57 mutant larvae injected with wild-type hmgcs1 RNA expresses plp1a at levels apparently equivalent to wild-type (I). Compared with wild-type (J), a vu57 mutant larva (K) and a vu57 mutant larva injected with mutant hmgcs1 RNA (L) express little mbp, whereas mbp expression is at high level in a vu57 mutant larva injected with wild-type hmgcs1 RNA (M). Scale bars, 20 μm.