The distribution of ephrin-B1 and PNA-positive glycoconjugates is correlated with atypical melanoblast migration in Japanese Silky fowl embryos.

Melanoblasts are positively stimulated to migrate in the dorsolateral pathway of the avian embryo by ephrins, but are inhibited by PNA-binding glycoconjugates. We analyzed the potential role of these molecules in the Japanese Silky fowl, which displays intense internal pigmentation. The distribution of ephrin ligands was analyzed using Eph receptor-human Fc fusion proteins. Glycoconjugates were labeled using PNA-FITC. In Japanese Silky embryos, ventral areas, including the anterior- and posterior-half somites, expressed ephrin-B1 in a pattern that correlates with the atypical migratory pathways taken by Japanese Silky melanoblasts. White Leghorn embryos displayed little to no ephrin-Bs in the ventral paths. Conversely, PNA-binding barrier tissues, proposed to prevent melanoblasts from migrating ventrally in White Leghorn, are missing or have significant gaps in Japanese Silky embryos. Thus, studies of a naturally occurring pigmentation mutant confirm that a combination of cues regulates melanoblast migration in the chick embryo.