#STRIPES ON HUMAN SKIN SKIN#

What is the origin of pigmentation loss in zebrafish golden mutants? Method Scale bars in (C) and (D), 1000 nm in (E) and (F), 200 nm. Melanosomes of gol b 1 larvae are fewer in number, smaller, less-pigmented, and irregular compared with wild type. gol b 1skin melanophores (arrowheads show edges) are thinner and contain fewer melanosomes than do those of wild type.

#STRIPES ON HUMAN SKIN SKIN#

Transmission electron micrographs of skin melanophore from 55-hpf wild-type ( C and E) and gol b 1 ( D and F) larvae. gol b 1 mutants have melanophores that are, on average, smaller, more pale, and transparent. Lateral views of adult wild-type ( A) and golden ( B) zebrafish. Despite its common use for the calibration of germ-line mutagenesis ( 10), the golden gene remained unidentified.įig. The first recessive mutation studied in zebrafish ( Danio rerio), golden ( gol b1), causes hypopigmentation of skin melanophores ( Fig. The zebrafish golden phenotype. The study of pigmentation variants ( 5, 8) has led to the identification of most of the known genes that affect pigmentation and has contributed to our understanding of basic genetic principles in peas, fruit flies, corn, mice, and other classical model systems. Nina Jablonski explains how melanin affects the color of our skin. Here we present evidence that the human ortholog of a gene associated with a pigment mutation in zebrafish, SLC24A5, plays a role in human skin pigmentation.Īnimation. Anthropologist Dr. Because the primary ultrastructural differences between melanocytes of dark-skinned Africans and lighter-skinned Europeans include changes in melanosome number, size, and density ( 6, 7), we reasoned that animal models with similar differences may contribute to our understanding of human skin color.

Melanin pigmentation abnormalities have been associated with inflammation and cancer, as well as visual, endocrine, auditory, and platelet defects ( 4).ĭespite the cloning of many human albinism genes and the knowledge of over 100 genes that affect coat color in mice, the genetic origin of the striking variations in human skin color is one of the remaining puzzles in biology ( 5). Melanin plays an important role in the protection of DNA from ultraviolet radiation ( 2) and the enhancement of visual acuity by controlling light scatter ( 3). The melanocytes of birds and mammals (homologous to melanophores in other vertebrates) produce the insoluble polymeric pigment melanin.

In vertebrates, body coloration is a function of specialized pigment cells derived from the neural crest ( 1). Pigment color and pattern are important for camouflage and the communication of visual cues. Watch this short film to understand what pieces of evidence have led scientists to conclude that different shades of skin color arose as adaptations to the intensity of UV radiation in different parts of the world. The study is remarkable for connecting basic model organism biology with human genetics to demystify how evolution can produce the rich diversity of skin color we see.

Its sequence varies between people of European and African ancestry, and through a collaborative effort, the authors found that these human SLC24A5 gene variants explain 25% of the skin pigmentation difference between those of European and African ancestry.

A gene of similar sequence and function also exists in humans (called SLC24A5), and like the golden gene, it encodes a membrane protein that affects melanosome production. They identified a golden gene ( slc24a5) that, when mutated, leads to more lightly pigmented, or 'golden,' fish. To better understand the genetic origin of skin color variation in humans, the authors turned to the zebrafish ( Danio rerio), a popular model organism, which-like humans-also displays variations in skin color. Although sunlight exposure contributes to skin pigmentation, much of the variation we see is likely genetic. The reason for these variations has been an enduring mystery of biology. Human skin color, determined by the pigment melanin, is a highly variable trait.

Stripes on human skin