Axon pathfinding proceeds normally despite disrupted growth cone decisions at CNS midline.

Axon pathfinding proceeds normally despite disrupted growth cone decisions at CNS midline Brian

Tyrosine kinase inhibition produces specific alterations in axon guidance in the grasshopper embryo.

Tyrosine kinase signaling pathways are essential for process outgrowth and guidance during nervous system development. We have examined the roles of tyrosine kinase activity in programming growth cone guidance decisions in an intact nervous system in which neurons can be individually identified. We applied the tyrosine kinase inhibitors herbimycin A and genistein to whole 40% grasshopper embryo...

Integrins regulate responsiveness to slit repellent signals.

Integrins are concentrated within growth cones, but their contribution to axon extension and pathfinding is unclear. Genetic lesion of individual integrins does not stop growth cone extension or motility, but does increase axon defasciculation and axon tract displacement. In this study, we document a dosage-dependent phenotypic interaction between genes for the integrins, their ligands, and the...

Zebrafish mutations affecting retinotectal axon pathfinding.

We have isolated mutants in the zebrafish Danio rerio that have defects in axonal connectivity between the retina and tectum. 5-day-old fish larvae were screened by labeling retinal ganglion cells with DiI and DiO and observing their axonal projections to and on the tectum. 82 mutations, representing 13 complementation groups and 6 single allele loci, were found that have defects in retinal gan...

Gradient steepness influences the pathfinding decisions of neuronal growth cones in vivo.

Gradients of chemotropic molecules are generally thought to be fundamental for the guidance of neuronal growth cones in the developing embryo. Here we show that the grasshopper-secreted semaphorin Sema 2a is expressed in a gradient during the period of tibial Ti1 pioneer axon pathfinding into the CNS. At two critical Ti1 growth cone choice points, the Sema 2a gradient differs in steepness, wher...