The spacing of feather buds in a tract is thought to arise from the interaction between an inducing signal from the dermis and an inhibitory signal generated in the nascent buds. Local BMP-2 expression in the ectoderm precedes the formation of the ectodermal placodes, which are the first morphological sign of bud differentiation. We have altered the… (More)
In the limb bud the 5' members of the Hox-4 gene cluster are expressed in a nested set of overlapping domains which are progressively restricted in the posterior and distal directions. These domains arise early in limb bud development and come to approximate the primordia of the major structural elements of the limb along the anterior/posterior axis (Fig.… (More)
An adaptive variant of the human Ectodysplasin receptor, EDARV370A, is one of the strongest candidates of recent positive selection from genome-wide scans. We have modeled EDAR370A in mice and characterized its phenotype and evolutionary origins in humans. Our computational analysis suggests the allele arose in central China approximately 30,000 years ago.… (More)
Limb buds in the limbless chick begin to form normally but fail to form an AER and ultimately degenerate. Wnt7a and LMX-1, which are restricted to the dorsal half of a normal limb bud, are expressed throughout the ectoderm and mesenchyme of the mutant buds, respectively. Engrailed-1, normally expressed in ventral limb ectoderm, is not expressed in the… (More)
In recent years, molecular analysis has led to the identification of some of the key genes that control the morphogenesis of the developing embryo. Detailed functional analysis of these genes is rapidly leading to a new level of understanding of how embryonic form is regulated. Understanding the roles that these genes play in development can additionally… (More)
In order to directly test the function of Hox genes in vertebrate limb development, we have employed a replication-competent retroviral vector to express the genes ectopically in developing chick limb buds. It has been hypothesized that the sum of all Hox genes expressed in a developing region forms a "Hox code" which determines the fate of structures… (More)
BACKGROUND Normal hematopoietic development depends on the activity of the Ikaros transcription factor, which contains distinct zinc-finger domains that mediate DNA binding and protein dimerization. Mice homozygous for a transgene encoding a dominant-negative version of Ikaros that lacks the DNA-binding domain but not the dimerization domain have a more… (More)
Although previous reports suggested that canonical Wnt signaling has opposing effects on epidermal and hair follicle stem cells, two recent papers (Choi et al., 2013; Lim et al., 2013) now show that Wnt signaling promotes proliferation in both stem cell populations, revealing new insights into regeneration of both skin compartments.