Date of Graduation

8-2019

Document Type

Thesis

Degree Name

Master of Science in Cell & Molecular Biology (MS)

Degree Level

Graduate

Department

Biological Sciences

Advisor

Timothy Evans

Committee Member

Allen Szalanski

Second Committee Member

Nagayasu Nakanishi

Abstract

Axons in the developing embryo receive and react to signals that direct their growth to reach target tissues at specified locations. The signal pathways that direct midline crossing of axons during embryonic development have been comprehensively examined in the past years using the Drosophila ventral nerve cord or the spinal cord as a model system. A number of these signaling mechanisms are conserved, however disparities have been found between species in general strategy or the molecular signals controlling the response of axons to guidance cues.

The Netrin-Frazzled pathway has been shown to aid in midline crossing of axons in the embryonic ventral nerve cord of Drosophila. However, It is uncertain if this function of Frazzled is conserved in other insects. The goals of this research are to gain insight into the evolutionary conservation of axon guidance by the Netrin receptor Frazzled (Fra)and to expand our understanding of how Frazzled affects midline crossing in the flour beetle Triboliumcastaneum.

The Frazzled ortholog in Tribolim is sufficient for replacing loss of function in Drosophila Fra. We also expect to see similar expression and function of Frazzled in beetles to those observed in Drosophila. These studies expand our knowledge of axon guidance of midline crossing in a species that does not share some of Drosophila’s derived guidance characters. Using Tribolium as an insect model for comparative studies of axon guidance may allow us to see a more ancestral guidance scheme.

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