Date of Award

2-25-1999

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

First Advisor

Kenneth Ruit

Abstract

Recent experimental approaches to the study of gene expression in the developing spinal cord have demonstrated the presence of neurotransmitters, growth factors and guidance cues that appear either at discrete times early in development or for extended periods of time throughout prenatal development and even into the postnatal period. Based on morphologic observations we have made previously in the developing rat thoracic spinal cord, the present study is designed to identify genes in the embryonic spinal cord that are expressed at very discrete developmental time points late in embryonic development. Our hypothesis is that previously unknown genes expressed at discrete times at later stages of prenatal development represent critical links in the chain of developmental processes necessary in establishing structural and functional diversity in the central nervous system, specifically the spinal cord. In order to describe the temporal differences in the expression of genes in the rat thoracic spinal cord at specific times during the last prenatal developmental week, RT-PCR differential display, cloning, northern blot analysis, nucleotide sequencing and in situ hybridization were utilized.One of the six differentially displayed gene fragments (17A2") was verified as truely differentially displayed with E17 expressing 2.5 times that expressed at E20. Control tissues also expressed the 17A2" fragment at E17 and E20. Based on partial nucleotide sequence analysis, homology to the human mitochondrial elongation factor was noted and in situ studies demonstrated mRNA by hybridization of 17A2" in E17 and E20. However, heavier labeling was noted in the E17 embryo with the densest labeling being in the lateral vental horn of the gray matter. The ubiquitous nature of the 17A2" gene fragment suggests that it is part of a multifunctional gene that is distributed throughout the tissues. This multifunctional gene appears to be upregulated in the E17 embryo in comparison to the E20 embryo, suggesting that in the middle of the last prenatal week significant molecular changes are occurring in the production, regulation and distribution of the 17A2" molecule.

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