Lavender corn snake

It all started when a wild-caught animal from the Sarasota-Punta Gorda area of Florida’s lower western coast was crossed with a captive animal; a Lavender offspring appeared in the F2 generation. Already for the first individual, it was noticed that “its slightly unusual chocolate brown appearance as a hatchling gradually changed as the animal grew and it lost the reddish tones” (Love K. & Love B., 2005). Descendants of the original Lavender individual have since been crossed with different morphs to produce mutants with more pale pigmentation.

The ‘corn snake skin colour project’ aims to identify the mutations that are responsible for the more than twenty spontaneously-occurring color and color pattern morphs observed in the species. Using a mapping-by-sequencing approach, we identified a 3.9Mb genomic interval where the Lavender mutation occurs. We located a single-nucleotide polymorphism that introduces a STOP codon in the LYST (lysosomal trafficking regulator) gene. Transmission electron microscopy of the Lavender skin revealed that the subcellular structure of all the chromatophores (melanophores, xanthophores and iridophores) was affected. The brown and black melanin pigments in mammals are produced in melanophore cells inside sub-cellular compartments called ‘Lysosome-Related Organelles’ (LROs). Our findings provide the first demonstration that xanthosomes (organelles containing red pigmentation in xanthophores) and iridosomes (organelles containing guanine crystals in iridophores) are also LROs. These results open a new research field to understand how melanin-producing nano-factories have been transformed during evolution into red/yellow pigment storing devices and guanine-crystalisation nano-machines.

Associated Publication
Ullate-Agote A., Burgelin I., Debry A., Langrez C., Montange F., Peraldi R., Daraspe J., Kaessmann H., Milinkovitch, M. C. M. & Tzika A. C.*
“Genome mapping of a LYST mutation in corn snakes indicates that vertebrate chromatophore vesicles are lysosome-related organelles ”
Proceedings of the National Academy of Sciences (PNAS) (2020)

Lavender corn snake morph A wild type (left) and a Lavender (right) corn snake.