The genes that control development of embryonic melanocytes are poorly defined. Although transcription factor Ap-2alpha is expressed in neural crest (NC) cells, its role in development of embryonic melanocytes and other neural crest derivatives is unclear because mouse Ap-2alpha mutants die before melanogenesis. We show that zebrafish embryos injected with morpholino antisense oligonucleotides ...

When a fish or a reptile changes color, it is because of the movement of tiny pigment granules in specialized skin cells called melanophores. These cells have hundreds of membrane-bound pigment granules, or melanosomes, which can be aggregated at the center of the cell or dispersed throughout the cytoplasm. When the melanosomes are aggregated the animal appears lighter, and as they disperse the...

Genetic studies of hybrids between the Mexican killifishes, Platypoecilus maculatus and Xiphophorus hellerii, have shown that when the black-spotted varieties of Platypoecilus are crossed with Xiphophorus, melanosis appears in some of the hybrid offspring. The distinguishing feature of these black-spotted varieties of Platypoecilus is the presence in the skin of a large type of black chromatoph...

The specification, differentiation and maintenance of diverse cell types are of central importance to the development of multicellular organisms. The neural crest of vertebrate animals gives rise to many derivatives, including pigment cells, peripheral neurons, glia and elements of the craniofacial skeleton. The development of neural crest-derived pigment cells has been studied extensively to e...

The pigment cells of vertebrates serve a variety of functions and generate a stunning variety of patterns. These cells are also implicated in human pathologies including melanoma. Whereas the events of pigment cell development have been studied extensively in the embryo, much less is known about morphogenesis and differentiation of these cells during post-embryonic stages. Previous studies of z...

In this work, we explored theoretically the transport of organelles driven along microtubules by molecular motors of opposed polarities using a stochastic model that considers a Langevin dynamics for the cargo, independent cargo-motor linkers and stepping motion for the motors. It has been recently proposed that the stiffness of the motor plays an important role when multiple motors collectivel...

Colour patterns of adult fish are composed of several different types of pigment cells distributing in the skin during juvenile development. The zebrafish, Danio rerio, displays a striking pattern of dark stripes of melanophores interspersed with light stripes of xanthophores. A third cell type, silvery iridophores, contributes to both stripes and plays a crucial role in adult pigment pattern f...

The transcription factor Sox10 is required for the specification, migration and survival of all nonectomesenchymal neural crest derivatives including melanophores. sox10(-/-) zebrafish lack expression of the transcription factor mitfa, which itself is required for melanophore development. We demonstrate that the zebrafish mitfa promoter has sox10 binding sites necessary for activity in vitro, c...

Many cellular components are transported using a combination of the actin- and microtubule-based transport systems. However, how these two systems work together to allow well-regulated transport is not clearly understood. We investigate this question in the Xenopus melanophore model system, where three motors, kinesin II, cytoplasmic dynein, and myosin V, drive aggregation or dispersion of pigm...

Morphological differentiation among closely related species provides opportunities to study mechanisms shaping natural phenotypic variation. Here, we address variation in the orientation of melanin-colored body stripes in three cichlid species of the tribe Haplochromini. Melanochromis auratus displays a common pattern of dark, straight horizontal body stripes, whereas in Aristochromis christyi ...