Figure 3. Expression of sept9 genes during zebrafish development.

Detection of sept9 mRNA was carried out by whole-mount in situ hybridization using a probe targeted to all sept9 isoforms on staged embryos from 256 cells to 24 hpf. Images in A–C are lateral views, animal pole to top; D and E are dorsal views, anterior to top; F and H are dorsal posterior views; G, I and J are lateral views, K is a dorsal view, anterior to left. A–C: sept9 transcripts are ubiquitously expressed at early developmental states. D: At bud stage, sept9 is expressed in endoderm and axis. E–H: sept9 is expressed in the floor plate, ventral mesoderm and tail bud during segmentation. I–K: At 24 hpf, sept9 is expressed throughout the epidermis, branchial arches, pectoral fin, and in the intermediate cell mass. L: Transcript specific primers were used to detect sept9a and sept9b transcripts in various stages of development by RT-PCR. sept9a_tv 2, 3, and α are expressed maternally. Amplification of eIFα and total RNA without addition of reverse transcriptase were used as controls. a, axis; ep, epidermis; fp, floorplate; icm, intermediate cell mass; tb, tail bud; vm, ventral mesoderm.