Myoglobin intron variation in the Gouldian Finch Erythrura gouldiae assessed by temperature gradient gel electrophoresis

In this study we show how the use of exon-primed, intron-crossing (EPIC) polymerase chain reaction (PCR) of a diploid intronic region, in conjunction with temperature gradient gel electrophoresis (TGGE), can be used to detect and rapidly assess allelic variation at the nucleotide level. We developed passerine-specific primers to amplify and sequence a 762 bp region including the second intron of the myoglobin gene in the Gouldian Finch, Erythrura gouldiae. A POLAND plot based on this sequence indicated that TGGE in combination with heteroduplex analysis (TGGE/HA) should reveal nucleotide variation in the 160 bp low-melting domain. Sequencing of the entire fragment from 19 Er. gouldiae revealed five nucleotide substitution differences within the low-melt domain, all of which could be detected and differentiated by TGGE/HA, and an additional substitution in a section of the high-melt domain which characterised another allele. A total of 181 individuals from four populations were screened for these six alleles.