منابع مشابه
How Hair Gets Its Pigment
Mutations in the transcription factor Foxn1 cause the nude phenotype in mice, which is characterized by a lack of visible hair. New work by Weiner et al. (2007) in this issue of Cell now shows that Foxn1 also contributes to hair color by marking which cells are to receive pigment from melanocytes.
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Leaves are formed from a group of initial cells within the meristem. One of the earliest markers of leaf initiation is the down-regulation of KNOX genes in initial cells. Polar auxin activity, MYB and LOB domain transcription factors function to keep KNOX out of the initiating leaf. If KNOX genes are expressed in initial cells, leaves fail to form. As the leaf grows away from the meristem, its ...
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The villi of the human and chick gut are formed in similar stepwise progressions, wherein the mesenchyme and attached epithelium first fold into longitudinal ridges, then a zigzag pattern, and lastly individual villi. We find that these steps of villification depend on the sequential differentiation of the distinct smooth muscle layers of the gut, which restrict the expansion of the growing end...
متن کاملHow the zebrafish gets its stripes.
The study of vertebrate pigment patterns is a classic and enduring field of developmental biology. Knowledge of pigment pattern development comes from a variety of systems, including avians, mouse, and more recently, the zebrafish (Danio rerio). Recent analyses of the mechanisms underlying the development of the neural crest-derived pigment cell type common to all vertebrates, the melanocyte, h...
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ammals exhibit a remarkable variety of coat patterns; the variety has elicited a comparable variety of explanations—many of them at the level of cogency that prevails in Rudyard Kipling's delightful "How the Leopard Got Its Spots." Although genes control the processes involved in coat pattern formation, the actual mechanisms that create the patterns are still not known. It would be attractive f...
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ژورنال
عنوان ژورنال: Optica Pura y Aplicada
سال: 2013
ISSN: 2171-8814,0030-3917
DOI: 10.7149/opa.46.3.i