Regulation of melanosome movement by MAP kinase.

Our objectives were to further characterize the signaling pathways in melatonin-induced aggregation in Xenopus melanophores, specifically to investigate a possible role of mitogen-activated protein kinase (MAPK). By Western blotting we found that melatonin activates MAPK, which precedes melanosome aggregation measured in a microplate reader. Activation of MAPK, tyrosine phosphorylation of a previously described 280-kDa protein, and melanosome aggregation are sensitive to PD98059, a selective inhibitor of MAPK kinase.

Biosensing of opioids using frog melanophores.

Spectacular color changes of fishes, frogs and other lower vertebrates are due to the motile activities of specialized pigment containing cells. Pigment cells are interesting for biosensing purposes since they provide an easily monitored physiological phenomenon. Melanophores, containing dark brown melanin pigment granules, constitute an important class of chromatophores.