Using our colony of corn snakes, next-generation sequencing, genotyping of SNPs, and sequencing candidate genes, we identify an insertion of an LTR-retrotransposon in the OCA2 gene as the causal mutation of amelanism in corn snakes. These results are published today in Scientific Reports.
We are promoting the corn snake (Pantherophis guttatus) as a new model particularly appropriate for investigating the processes generating colours in reptiles because numerous colour and pattern mutants of this species have been bred in the last five decades. Using our captive-bred colony of corn snakes, transcriptomic and genomic next-generation sequencing, exome assembly, and genotyping of SNPs in multiple families, we delimit the genomic interval bearing the causal mutation of amelanism, the oldest colour variant identified in that species. Proceeding with sequencing the candidate gene OCA2 in the uncovered genomic interval, we identify that the insertion of an LTR-retrotransposon in its 11th intron results in a considerable truncation of the p protein and constitutes the causal mutation of amelanism in corn snakes. As amelanistic snakes exhibit white, instead of black, borders around an otherwise normal pattern of dorsal orange saddles and lateral blotches, our results indicate that melanocytes lacking melanin are able to participate to the normal patterning of other colours in the skin. In combination with research in the zebrafish, this work opens the perspective of using corn snake colour and pattern variants to investigate the generative processes of skin colour patterning shared among major vertebrate lineages.
Much additional info is available in the Original Article:
Amelanism in the corn snake is associated with the insertion of an LTR-retrotransposon in the OCA2 gene
Saenko S.V., Lamichhaney S., Martinez Barrio A., Rafati N., Andersson L. & M. C. Milinkovitch
Scientific Reports 5, 17118 (2015)
Download here the UNIGE press release about these and other results.
Note that identification of other mutations responsible for multiple variations of snake skin coloration will be greatly facilitated in the future thanks to the availability of the corn snake genome and transcriptome.