Characterization and Classification of Danio Rerio Brain Ventricle Mutant schnitter

Abstract

Brain ventricles have been shown to have a number of different crucial roles in the brain. However, the specific molecular mechanisms underlying brain ventricle formation during vertebrate development remain largely unknown. Recently, Danio rerio have been increasingly utilized as a model organism in order to study brain ventricle morphogenesis in vertebrates. Studying zebrafish brain ventricle mutants generated in large-scale mutagenesis screens allows for identification of genes and mechanisms which may play a role in the process. This thesis aimed to characterize the zebrafish brain ventricle mutant strain schnitter. Brain ventricle injections with fluorescein dye and BODIPY ceramide staining allowed for visualization of the brain ventricle morphology in the mutant, revealing that the strain exhibits neural tube midline separation defects at 24 hours post-fertilization. In addition, attempts were made to identify the gene mutated in schnitter by screening three candidate genes: rhotekin 2 (rtkn2), nk2 transcription factor related 2a (nkx2.2a), and nuclear receptor binding factor 2 (nrbf2). The expression patterns for the candidate genes were analyzed by RNA in situ hybridization and the sequences for the genes were compared between schnitter and wild-type sibling embryos. The results from this thesis indicate that schnitter rtkn2 exhibits significant missense mutations in a crucial effector region of the protein compared to wild-type siblings, suggesting that it may be the mutated gene in the strain causing the abnormal brain ventricle phenotype.