Nervous system

About: Nervous system is a research topic. Over the lifetime, 16729 publications have been published within this topic receiving 847181 citations.

Wnt-mediated axon guidance via the Drosophila Derailed receptor

Abstract: In nervous systems with bilateral symmetry, many neurons project axons across the midline to the opposite side. In each segment of the Drosophila embryonic nervous system, axons that display this projection pattern choose one of two distinct tracts: the anterior or posterior commissure. Commissure choice is controlled by Derailed, an atypical receptor tyrosine kinase expressed on axons projecting in the anterior commissure. Here we show that Derailed keeps these axons out of the posterior commissure by acting as a receptor for Wnt5, a member of the Wnt family of secreted signalling molecules. Our results reveal an unexpected role in axon guidance for a Wnt family member, and show that the Derailed receptor is an essential component of Wnt signalling in these guidance events.

Segmentation in the vertebrate nervous system

Abstract: Although there is good evidence that growing axons can be guided by specific cues during the development of the vertebrate peripheral nervous system, little is known about the cellular mechanisms involved. We describe here an example where axons make a clear choice between two neighbouring groups of cells. Zinc iodide-osmium tetroxide staining of chick embryos reveals that motor and sensory axons grow from the neural tube region through the anterior (rostral) half of each successive somite. 180 degrees antero-posterior rotation of a portion of the neural tube relative to the somites does not alter this relationship, showing that neural segmentation is not intrinsic to the neural tube. Furthermore, if the somitic mesoderm is rotated 180 degrees about an antero-posterior axis, before somite segmentation, axons grow through the posterior (original anterior) half of each somite. Some difference therefore exists between anterior and posterior cells of the somite, undisturbed by rotation, which determines the position of axon outgrowth. It is widespread among the various vertebrate classes.

Neurotrophin-6 is a new member of the nerve growth factor family.

Abstract: During vertebrate development, many neurons depend for survival and differentiation on their target cells The best documented mediator of such a retrograde trophic action is the neurotrophin nerve growth factor (NGF) NGF and the other known members of the neurotrophin family, brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3) and neurotrophin-4/5 (NT-4/5) are conserved as distinct genes over large evolutionary distances Here we report the cloning of neurotrophin-6 (NT-6), a new member of this family from the teleost fish Xiphophorus NT-6 distinguishes itself from the other known neurotrophins in that it is not found as a soluble protein in the medium of producing cells The addition of heparin (but not chondroitin) effects the release of NT-6 from cell surface and extracellular matrix molecules Recombinant purified NT-6 has a spectrum of actions similar to NGF on chick sympathetic and sensory neurons, albeit with a lower potency NT-6 is expressed in the embryonic valvulla cerebelli; expression persists in some adult tissues The interaction of NT-6 with heparin-binding molecules may modulate its action in the nervous system