Identification of MC1R alleles in Nerodia clarkii compressicauda in order to gain insight into the genetics of color variation
Andrea Gaynor
The goal of this research project was to determine if the MC1R gene is responsible for the color variation in a subspecies of Nerodia clarkii. The Mangrove Salt Marsh snake, Nerodia clarkii compressicauda, is found in mangrove habitats along the southern coast of Florida. These snakes are nonvenomous and come in a variety of color morphs. Melanocortin-1 receptor, MC1R, is a receptor gene that is known to play a key role in regulating the production of pigment in vertebrates. The protein transcribed from this gene is located on the surface of melanocytes and helps to regulate the production of eumelanin and pheomelanin, which are black and red pigments, respectively. In Nerodia clarkii compressicauda, color morphs can range from tan to brownish red or gray to black, which could be indicative of variations in MC1R function. Two red snakes that were born in captivity were able to produce black and red offspring in controlled crosses, suggesting that red is dominant over black. To understand the relationship between MC1R genotype and the organism phenotype, the MC1R alleles in the parents and their offspring were identified by DNA sequencing. MC1R DNA was amplified by PCR from individual animals to be inserted into the pBluescript plasmid. After transformation, individual colonies should contain only one of the two alleles from an individual. Colonies were cultured for plasmid purification by the alkaline lysis method. The plasmid DNA is currently being sequenced from multiple clones to identify the two alleles for each individual animal. This sequencing data should allow for the establishment of a model of allelic inheritance, which will be compared to phenotypic inheritance.
Andrea Gaynor is a senior in biology genetics emphasis with a minor in chemistry. She is a member of the TriBeta honors society and has been conducting undergraduate research since the fall of 2020. Once she graduates from Lander, she will be pursuing her PhD at Clemson University.