Automated single-strand conformation polymorphism reveals low diversity of a Major Histocompatibility Complex Class II gene in the threatened New Zealand sea lion

Single-strand conformation polymorphism (SSCP) analysis of the second exon of the DQB gene in the endemic New Zealand sea lion (Phocarctos hookeri) was automated using fluorescently-labelled PCR primers and a capillary sequencer. SSCP mobility profiles (n = 61 individuals) were confirmed by direct sequencing of genomic polymerase chain reaction (PCR) products (n = 39). We found only two alleles defined by changes at a single codon of this apparently functional locus. SSCP at a constant temperature above ambient allowed consistent and rapid genotyping. By comparison, sequence-based genotyping was highly dependent on the threshold used to identify secondary peaks indicative of a heterozygote.