The function of Cxcl12b in habenular axon projection in zebrafish

Abstract

The habenula is a structure found in the midbrain that is associated with regulating emotion and behavior. Research shows that chemokine signaling is involved in proper axon growth and direction as the habenula connects to its midbrain target, the interpeduncular nucleus (IPN). Transcripts of the chemokine receptor, cxcr4b, are found in precursors of the habenula, and Cxcr4b is present in newly formed habenular axons. The chemokine ligand Cxcl12b is expressed posterior to habenular axons as they extend toward the IPN. Previous work has shown that overexpression of cxcl12b coincides with abnormal axon development. The purpose of this research is to understand what affect loss of Cxcl12b has on proper axon projection from the habenula.  We have produced fish with both a fluorescent marker of the habenula and a mutation in cxcl12b. After imaging their habenulae, we collect their DNA and genotype the larvae. The habenular axons of homozygous mutants will be compared to those of their heterozygous and wild type siblings. We hypothesize that cxcl12b mutation will result in improper habenular axon projection toward the IPN.