Different protein synthetic patterns in scale-forming, feather-forming, and apteric embryonic chick dermis

We have examined the protein synthetic profile of embryonic chick dermis from different regions of both wild-type and scaleless mutant embryos by two-dimensional polyacrylamide gel electrophoresis to determine if differences in inductive capability are associated with different patterns of gene expression. We have found proteins preferentially synthesized in dorsal dermis and anterior tarsometatarsal dermis at stages when these tissues are active in inducing feather or scale histogenesis, respectively, in the epidermis. Apteric dermis, which is unable to induce epidermal derivative formation, synthesizes a subset of the proteins specific to each region. Scaleless mutant dermis, which does not participate in feather or scale formation in vivo, synthesizes all of the dorsal dermis-specific or tarsometatarsal dermis-specific proteins appropriate to its regional origin. However, it lacks one protein common to all types of dermis tested, and synthesizes one protein inappropriate for its location. Examination of the protein synthetic profile of dorsal and anterior tarsometatarsal dermis at early stages of development reveals that young dorsal dermis, which can only form feathers, possesses the protein synthetic pattern specific to that region. Young tarsometatarsal dermis, which has the potential to form either feathers or scales, synthesizes the proteins we have identified as specific to dorsal and older tarsometatarsal dermis. These results suggest that different protein synthetic patterns are associated with different inductive potentials. However, combining young tarsometatarsal dermis with dorsal epidermis, which causes the formation of feathers, does not alter the pattern of proteins synthesized by the dermis. While this result may be due to an artifact of the culture system, an alternative explanation is that the protein synthesis pattern is not related to the type of epidermal derivative induced, but to the pattern in which the derivatives are induced. This is supported by the observation that the feathers formed in recombinants of tarsometatarsal dermis and dorsal epidermis are arranged in a scale pattern.