Magnetoreception is essential for magnetic orientation in animal migration. The 
molecular basis for magnetoreception has recently been elucidated in fruitfly as 
complexes between the magnetic receptor magnetoreceptor (MagR) and its ligand 
cryptochrome (Cry). MagR and Cry are present in the animal kingdom. However, it 
is unknown whether they perform a conserved role in diverse animals. Here we 
report the identification and expression of zebrafish MagR and Cry homologs 
towards understanding their roles in lower vertebrates. A single magr gene and 7 
cry genes are present in the zebrafish genome. Zebrafish has four cry1 genes 
(cry1aa, cry1ab, cry1ba and cry1bb) homologous to human CRY1 and a single 
ortholog of human CRY2 as well as 2 cry-like genes (cry4 and cry5). By RT-PCR, 
magr exhibited a high level of ubiquitous RNA expression in embryos and adult 
organs, whereas cry genes displayed differential embryonic and adult expression. 
Importantly, magr depletion did not produce apparent abnormalities in 
organogenesis. Taken together, magr and cry2 exist as a single copy gene, 
whereas cry1 exists as multiple gene duplicates in zebrafish. Our result 
suggests that magr may play a dispensable role in organogenesis and predicts a 
possibility to generate magr mutants for analyzing its role in zebrafish.