Establishing a positional information assay for brain ventricle mutants and investigating the choroid plexuses in zebrafish

Abstract

The process by which the neural tube expands into three brain ventricles can be understood through genetic mutant analysis. Within the framework of a characterization of zebrafish mutants with brain ventricle phenotypes, I have developed an assay that looks for evidence of compromised gene expression patterns. I have shown that a cocktail of krox20, pax2a, shh, and zicl antisense RNA probes hybridizes to domains in the developing brain that reflect anterior, posterior, dorsal, and ventral axis specification. In addition, I have investigated the choroid plexus (CP) cells lining the brain ventricles in the zebrafish. Though we were unable to clearly identify the CP in the adult brain, we did identify two homologues in zebrafish of a conserved gene expressed in CP of vertebrates. We found that one of these genes, Drcpllb, was expressed from tailbud into early larva stage. Further, Drcpllb is expressed in neurula stage embryos in the anterior neural plate. Through these studies, we established an assay to analyze positional identity of cells in the neural tube and discovered a potential choroid plexus marker, shown its expression time course, and outlined its early expression pattern in the zebrafish.