Molecular genetic analysis of Drosophila neuroglian

Stephen Grow Hall, Purdue University

Abstract

Drosophila Neuroglian is a cell surface glycoprotein and a member of the immunoglobulin (Ig-like) superfamily, a group of Ca$\sp{2+}$-independent cell adhesion molecules. The two different Neuroglian protein products differ in their cytoplasmic domains and are generated by tissue-specific alternate splicing. The short form of Neuroglian is expressed in the brain, on all muscle domains, in trachea, and gut. The long form is expressed only on neuronal and nonneuronal surfaces in the central and peripheral nervous system. We have identified three embryonic lethal mutations in the Neuroglian locus that alter or abolish expression. These mutations have been used to analyze Neuroglian's function during development. Using a temperature-sensitive Neuroglian mutation, the phenocritical period has been determined to be during late embryogenesis which correlates with the onset of neuromuscular specificity. Analysis of the Neuroglian mutant nervous system reveals that there are patterning defects in the peripheral nervous system. There are also profound defects in the trajectories of motoneurons as well as a failure of the growth cones to innervate muscles. The extensive expression pattern of Neuroglian on all motoneurons and muscles presents the most absolute example of pre and post synaptic specificity in Drosophila to date. This combined with the phenotype demonstrates that Neuroglian is a gene necessary for neuron pathfinding and neuromuscular target recognition, and that its proper expression is absolutely required for viability and nervous system development.

Degree

Ph.D.

Advisors

Bieber, Purdue University.

Subject Area

Genetics|Neurology|Molecular biology

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