The melanocortin-1 receptor gene (mc-1r) and color polymorphism in plethodon cinereus

The salamander, Plethodon cinereus, is commonly found in two different color phases; the red-back phase and the lead-back phase. The molecular basis behind these different color morphs is not fully understood. In this study, the gene for the melanocortin-1 receptor (MC-1R) was sequenced to see if mutations in this gene are responsible for these color differences. MC-1R is a G protein-coupled receptor that plays an important role in pigmentation and melanin production in skin, hair, and feathers. Mutations in this protein appear to correspond to light or dark phenotypes in many different animals. It was hypothesized that mutations in MC-1R are responsible for the polymorphism in Plethodon cinereus. Frozen tissue of salamanders caught near the Helderberg Escarpment was used to isolate, amplify and sequence a 692 base pair fragment of MC-1R. We sequenced the PCR products from six animals representing the two color morphs and found two variable sites at nucleotide numbers 495 and 528. ARMS-PCR indicated that red-backs are homozygous at site 495