BEHAVIOURAL ANALYSIS OF ZEBRAFISH RELAXIN-3A MUTANT

Abstract

The insulin-related neuropeptide relaxin-3 (RLN3) has been implicated in stress responses, feeding and anxiety. Most studies have focused on the peptide encoded by the A- and B-chains, and have been conducted using rodents. This thesis explores the <i>rln3a</i> gene in zebrafish, to test whether these roles are evolutionarily conserved. Using CRISPR/Cas9, a 7 bp deletion was generated in the <i>rln3a</i> locus. Mutants showed mild changes in body weight, anxiety and visuomotor response compared to wildtype siblings. A single nucleotide polymorphism (c.158C>T) was found, resulting in a non-synonymous mutation in the coding sequence of the C-peptide. Fish with the c.158C>T polymorphism had increased activity in visual motor response that was dependent on genetic background. Using mutant fish, there was little evidence for a role in stress responses in the rln3 peptide, similar to rodent studies. Instead, the data suggests a possible function for the C-peptide.