Alignment of VH and partial CH1 of IgM cDNA clones. The deduced amino acid sequences of 25 IgM cDNA clones (Genbank accession # AY609247-AY609274) were aligned with the conventional adult nurse shark IgM (Genbank accession #M92851 ) in ClustalW. Dashes (-) indicate identity with the first sequence and gaps introduced to correct alignment are indicated by slashes (/). Identification of framework and CDR are based on previous work . Differences in the framework and CDR separated the clones into six groups (I-VI). The CDR3 varies in length and sequence thus most clones are unique, demonstrating diversity is present at birth in the nurse shark.