Nedd4, a ubiquitin-protein ligase, was originally identified as being down-regulated during development of the mouse brain (Nedd denotes neural precursor cell expressed developmentally down-regulated) (Kumar, S., Tomooka, Y., Noda, M., 1992. Identification of a set of genes with developmentally down-regulated expression in the mouse brain. Biochem. Biophys. Res. Commun. 185, 1155-1161). Subtrac...

We report new skeletal elements pertaining to the same individual which represents the holotype of Australovenator wintonensis, from the 'Matilda Site' in the Winton Formation (Upper Cretaceous) of western Queensland. The discovery of these new elements means that the hind limb of Australovenator is now the most completely understood hind limb among Neovenatoridae. The new hind limb elements in...

Electron microscopical study of the formation of the hind limb of the toad Xenopus laevis between stages 49 and 53 of larval development has been performed with special reference to the relationships between the apical ectodermal ridge and the underlying mesenchyme. It has been found that the intervening collagenous layer is thinner in the vicinity of the ridge than elsewhere and that the subja...

Hereditary Multiple Malformation (HMM) is a naturally occurring, autosomal recessive, homozygous lethal mutation found in Japanese quail. Homozygote embryos (hmm-/-) show polydactyly similar to talpid2 and talpid3 mutants. Here we characterize the molecular profile of the hmm-/- limb bud and identify the cellular mechanisms that cause its polydactyly. The hmm-/- limb bud shows a severe lack of ...

BACKGROUND Retinoic acid (RA) is present in the chick limb bud, and excess RA induces limb duplications. Here, we have investigated the role of endogenous RA during chick limb development by preventing the synthesis of RA and testing the effect on various genes expressed during limb initiation and outgrowth. RESULTS We demonstrate that the stage 20/21 limb bud synthesizes didehydroretinoic ac...

Outgrowth of normal chick limb bud mesoderm is dependent on the presence of a specialized epithelium called the apical ectodermal ridge. This ectodermal ridge is induced by the mesoderm at about the time of limb bud formation. The limbless mutation in the chick affects apical ectodermal ridge formation in the limb buds of homozygotes. The initial formation of the limb bud appears to be unaffect...

BACKGROUND The outgrowth of the vertebrate limb bud is the result of a reciprocal interaction between the mesenchyme and a specialized region of the ectoderm, the apical ectodermal ridge (AER), which overlies it. Signals emanating from the AER act to maintain the underlying mesenchyme, called the progress zone, in a highly proliferative and undifferentiated state. Removal of the AER results in ...

BACKGROUND An inexpensive method of generating continuous data on hind limb function in dogs with spinal cord injury is needed to facilitate multicentre clinical trials. This study aimed to define normal fore limb, hind limb coordination in dogs walking on a treadmill and then to determine whether reliable data could be generated on the frequency of hind limb stepping and the frequency of coord...

The undifferentiated vertebrate limb bud is a selforganizing system. If transplanted to a favorable ectopic location, the limb bud is capable of developing into a morphologically normal limb (Harrison, 1918), and the anterior-posterior polarity of the transplanted limb is determined by the graft rather than the host environment. Great progress has recently been made in understanding the molecul...

BACKGROUND The vertebrate limb is a classical model for understanding patterning of three-dimensional structures during embryonic development. Although decades of research have elucidated the tissue and molecular interactions within the limb bud required for patterning and morphogenesis of the limb, the cellular and molecular events that shape the limb bud itself have remained largely unknown. ...