The researchers determined that the scaleless phenotype is due to a recessive gene in the single locus variant, or sequence types that differ by one allele type.
Researchers at the University of Geneva and University of Zurich have created the first gene edited snake using CRISPR-Cas9 gene editing system, in an effort to show that internal anatomic structures of snakes guide how the scales of snakes are positioned to aid in their movement, or locomotion.
In doing so, the researchers created the world’s first genetically modified corn snake using CRISPR-Cas9. The researchers say the snakes do not have dorso-lateral scales because they have a disrupted EDARADD gene (which enables the ectoderm and mesoderm to interact), but do possess fairly normal ventral scales. These ventral scales form independently and their patterning is defined by positional information that is derived from somitic tissues. These tissues form in the embryonic stage of somitogenesis.
Fig. 1. Scaled and scaleless corn snakes.
(A and B) Scale distribution in a scaled (A) and a scaleless (B) adult corn snake. A dorsal view (left) and close-ups of lateral, ventral, and head views (right) are shown. Adult corn snakes measure approximately 1.2 m. (C and D) Micrographs of dorsal scales (top; scale bars, 500 μm) and interscale skin (bottom; scale bars, 50 μm) of a scaled (C) and a scaleless (D) animal.
The researchers injected pre-vitellogenic oocytes into five scaled female corn snakes to produce gene edited snakes. They bred scaleless corn snakes (first reported in 2002 by a breeder who bred a corn snake with a Great Plains rat snake (Pantherophis emoryi) with scaled corn snakes (Pantherophis guttatus). By manipulating the RNA, the researchers created a successful corn snake fibroblast cell line. The treated females were then paired with scaleless males and two heterozygous males.
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The females laid 69 eggs, of which 54 hatched. Of the 54, four were scaleless, produced by two of the three females that were bred with a scaleless male. The remaining hatchlings were scaled. The researchers determined that the scaleless phenotype is due to a recessive gene in the single locus variant, or sequence types that differ by one allele type.
The complete paper, “Somitic positional information guides self-organized patterning of snake scales” can be read on the Science Advances website.
