Project description:Background: Snakes exhibit a broad variety of adaptive colours and colour patterns, generated by the spatial arrangement of chromatophores, but little is known of the mechanisms responsible for these spectacular traits. Here, we investigate a monolocus trait with two recessive alleles that cause pattern aberrations in the corn snake: the motley and striped alleles. Results: We use mapping-by-sequencing to identify the genomic interval where the causal mutations reside. With our differential gene expression analyses, we find that CLCN2 (Chloride Voltage-Gated Channel 2), a gene within the genomic interval, is significantly downregulated in Motley embryonic skin. Furthermore, the insertion of a retrotransposon in CLCN2 results in a disruptive mutation in Stripe. We confirm the involvement of CLCN2 in colour pattern formation by producing knock-out snakes that present a phenotype similar to the Stripe one. In humans and mice, the disruption of CLCN2 results in leukoencephalopathy, as well as retinal and testes degeneration. Our single-cell transcriptomic analyses reveal that CLCN2 is indeed expressed in chromatophores during embryogenesis and in the adult brain. Although, we observe signs of vacuolation in the Stripe adult brain, the retina of Motley and Stripe animals is intact, and no fertility issues are reported for the carriers of both alleles. Conclusions: Our genomic, transcriptomic and functional analyses identify a plasma membrane anion channel to be involved in colour pattern development in Squamate reptiles and show that an active LTR-retrotransposon might be a key driver of trait diversification in corn snakes.
Project description:Background: Snakes exhibit a broad variety of adaptive colours and colour patterns, generated by the spatial arrangement of chromatophores, but little is known of the mechanisms responsible for these spectacular traits. Here, we investigate a monolocus trait with two recessive alleles that cause pattern aberrations in the corn snake: the motley and striped alleles. Results: We use mapping-by-sequencing to identify the genomic interval where the causal mutations reside. With our differential gene expression analyses, we find that CLCN2 (Chloride Voltage-Gated Channel 2), a gene within the genomic interval, is significantly downregulated in Motley embryonic skin. Furthermore, the insertion of a retrotransposon in CLCN2 results in a disruptive mutation in Stripe. We confirm the involvement of CLCN2 in colour pattern formation by producing knock-out snakes that present a phenotype similar to the Stripe one. In humans and mice, the disruption of CLCN2 results in leukoencephalopathy, as well as retinal and testes degeneration. Our single-cell transcriptomic analyses reveal that CLCN2 is indeed expressed in chromatophores during embryogenesis and in the adult brain. Although, we observe signs of vacuolation in the Stripe adult brain, the retina of Motley and Stripe animals is intact, and no fertility issues are reported for the carriers of both alleles. Conclusions: Our genomic, transcriptomic and functional analyses identify a plasma membrane anion channel to be involved in colour pattern development in Squamate reptiles and show that an active LTR-retrotransposon might be a key driver of trait diversification in corn snakes.
Project description:The fur of the common brushtail possum (Trichosurus vulpecula), a model marsupial, is lightweight, soft and has superior insulation properties. Two predominate fur colours exisit: grey or black. RNA-sequencing of skin from grey (n=3) and black (n=3) possums was performed to investigate gene expression changes between these colour morphs.
