Our earlier studies have demonstrated that exposure of Caucasoid skin to longwave uv light after the application of psoralens resulted in an increase in the average size of the melanosomes and changes in the distribution pattern of melanosomes within the keratinocytes. The photobiologic mechanism responsible for the changes in the size of melanosomes is still not clear. However, the action spec...

Microtubule (MT)-based transport of organelles driven by the opposing MT motors kinesins and dynein is tightly regulated in cells, but the underlying molecular mechanisms remain largely unknown. Here we tested the regulation of MT transport by the ubiquitous protein MAP4 using Xenopus melanophores as an experimental system. In these cells, pigment granules (melanosomes) move along MTs to the ce...

The melanosome is a highly specialized organelle where melanin is synthesized. Tyrosinase and tyrosinase-related protein-1 (Tyrp1) are major melanosomal membrane proteins and key enzymes for melanin synthesis in melanocytes. Inulavosin, a melanogenesis inhibitor isolated from Inula nervosa (Compositae), reduced the melanin content without affecting either the enzymatic activities or the transcr...

Iridescent feather colors involved in displays of many extant birds are produced by nanoscale arrays of melanin-containing organelles (melanosomes). Data relevant to the evolution of these colors and the properties of melanosomes involved in their generation have been limited. A data set sampling variables of extant avian melanosomes reveals that those forming most iridescent arrays are distinc...

Those of us experiencing graying hair may be more sensitive to the term melanosome than other readers. You will find no remedy within this article, but rather a jealous look at the organisms which are able to manipulate their skin color, for example to match the appearance of their environment. In fish and amphibians, this change is brought about by movements of pigment-containing vesicles, mel...

The mechanism(s) by which Rab GTPases are specifically recruited to distinct intracellular membranes remains elusive. Here we used Rab27a localisation onto melanosomes as a model to investigate Rab targeting. We identified the α1 subunit of Na+,K+-ATPase (ATP1a1) as a novel Rab27a interacting protein in melanocytes and showed that this interaction is direct with the intracellular M4M5 loop of A...

Investigation of feathers from the famous Middle Eocene Messel Oil Shale near Darmstadt, Germany shows that they are preserved as arrays of fossilized melanosomes, the surrounding beta-keratin having degraded. The majority of feathers are preserved as aligned rod-shaped eumelanosomes. In some, however, the barbules of the open pennaceous, distal portion of the feather vane are preserved as a co...

Melanosomes without the characteristic structure of normal melanocytes have been found in experimental melanomas and human nodular melanomas (1-3). They are associated with a unique type of premelanosome, the granular body (1, 2, 4, 5). Melanosomes and premelanosomes in melanomas are tyrosinase positive, but it has been shown that they also contain lysosomal enzymes (6-8). Novikoff et al. (6) p...

Many animals change their body pigmentation according to illumination of their environment. In aquatic vertebrates, this reaction is mediated through aggregation or dispersion of melanin-filled vesicles (melanosomes) in dermal pigment cells (melanophores). The adaptive value of this behavior is usually seen in camouflage by allowing the animal to visually blend into the background. When exposed...

This study elucidates the nature of melanogenesis in B16 and Harding-Passey (HP) mouse melanomas producing melanin and melanosomes of different color and fine structure, i.e., brownblack eumelanosome-like B16 granules and reddish brown pheomelanosome-like HP granules, and compares them with "typical" 3,4-dihydroxyphenylalanine (DOPA) and sepia eumelanins and sepia eumelanosomes. The melanin con...