In the developing ventral midbrain, the signaling molecule sonic hedgehog (SHH) is sufficient to specify a striped pattern of cell fates (midbrain arcs). Here, we asked whether and precisely how hedgehog (HH) signaling might be necessary for ventral midbrain patterning. By blocking HH signaling by in ovo misexpression of Ptc1(Delta)(loop2), we show that HH signaling is necessary and can act dir...

Are there related proteins? Lots. In mammals, Sonic is related to two other hedgehogs: Indian and Desert. When expressed appropriately, the three proteins can substitute for one another but they do have unique functions: Desert hedgehog is needed for spermatogenesis and Indian hedgehog regulates cartilage differentiation. In the zebrafish, Sonic is related to Tiggywinkle hedgehog — which is tho...

The past few years have seen an increase in interest about the molecular and genetic events regulating pancreas development. Transcription factors such as Pdx1, p48 and Nkx2.2 have been shown to be essential for the proper differentiation of exocrine and endocrine tissue; however, pancreas development also involves intricate interactions between the pancreatic epithelium and its surrounding mes...

thinking would result in increased diabetes-related goal setting. Goals during the late adolescent period would be developmentally appropriate, such as self-managing their diabetes in order to spend more time away from home with peers. However, what goals are set throughout the stages of adolescence remains unstudied. Risk and Protective Factors Health status and individual factors often influe...

Sonic hedgehog (SHH) is a member of the hedgehog family of signalling molecules. SHH was initially described as a protein secreted from two signalling centres, the notochord and the floor plate. Subsequently, it was identified as a morphogen that is directly responsible for dorso-ventral patterning of the CNS. More recently, additional sites of SHH expression have been identified and multiple a...

Department of Urology, University of Illinois at Chicago, Chicago, IL 60612, USA; Department of Biosciences, Rice University, Houston, TX 77005, USA; Simpson-Querrey Institute for BioNanotechnology, Department of Chemistry, Department of Materials Science and Engineering, and Biomedical Engineering, Northwestern University, Feinberg School of Medicine, Chicago, IL 60611, USA; Division of Urolog...

After midline crossing, axons of dorsolateral commissural neurons turn rostrally into the longitudinal axis of the spinal cord. In mouse, the graded distribution of Wnt4 attracts post-crossing axons rostrally. In contrast, in the chicken embryo, the graded distribution of Sonic hedgehog (Shh) guides post-crossing axons by a repulsive mechanism mediated by hedgehog-interacting protein. Based on ...

To examine the role of development in the origin of evolutionary novelties, we investigated the developmental mechanisms involved in the formation of a complex morphological novelty-branched feathers. We demonstrate that the anterior-posterior expression polarity of Sonic hedgehog (Shh) and Bone morphogenetic protein 2 (Bmp2) in the primordia of feathers, avian scales, and alligator scales is c...

While the ventralizing factor Sonic hedgehog is expressed in the entire notochord (Development 121 (1995) 2537) the latter displays distinct ventralizing activities along its rostrocaudal axis. Hence, in HH stage-10 chicken embryo, the caudal notochord exhibits floor plate inducing capacities lost by rostral regions (Development 117 (1993) 205). Therefore, we hypothesize that the caudal notocho...

The thalamus is a central brain region that plays a crucial role in distributing incoming sensory information to appropriate regions of the cortex. The thalamus develops in the posterior part of the embryonic forebrain, where early cell fate decisions are controlled by a local signaling center - the mid-diencephalic organizer - which forms at the boundary between prospective prethalamus and tha...