Genes and the Pigment Cells of Mammals

Abstract

In order to exemplify the many diverse ways in which gene action can influence or suppress pigment production, this discussion is mainly concerned with analyzing how a few well-studied coat-color factors of the mouse produce their phenotypic effect. This analysis demonstrates that melanoblast differentiation and melanin synthesis proceed through an orderly sequence of genetically controlled steps, any one of which can be influenced in various ways. While some coat-color genes are involved in early steps in melanoblast differentiation (W, Miwh, Sp), melanocyte morphology (D, Ln), or the basic protein structure of the melanin granule (P), others produce their effect by controlling tyrosinase synthesis (C) or the polymerization of melanin (A, B). Although much work still remains to be done in tracing the phenotypic effects of these specific loci even farther back, to the time and place of their primary action, these studies have already contributed much to an understanding of how gene action and gene interaction can influence a single mammalian character.