It has been proposed that the various 14-3-3 isotypes and isoforms present in all eukaryotes are largely functionally equivalent. However, this is not consistent with the conservation of multiple isoforms and isotypes, especially in vertebrates with seven 14-3-3 encoding genes and nine isotypes. The hypothesis tested in this thesis is that both isoform-specific and overlapping functions are likely mediated through tissue specific expression, colocalization and dimerization of 14-3-3 proteins occur in vivo. Drosophila melanogaster was selected because it offers a simple, but representative system to study these proteins functionally. This thesis focuses primarily on D14-3-3?, although the expression pattern and phenotypes associated with all three Drosophila 14-3-3s were determined. I first determined the expression pattern of the three different 14-3-3 isotypes (leoI, leoII and D14-3-3?) and described developmental phenotypes associated with mutations in 14-3-3 isotypes in Drosophila. I found that there is partial redundancy with respect to lethality. Both LEO and D14-3-3? appear required for normal germ-line and somatic gonadal development. However, they do not appear to be functionally equivalent with respect to this phenotype since LEO is unable to compensate for the loss of D14-3-3?. I also determined that D14-3-3? mutants have unique phenotypes including deficits in adult cross-vein formation and rapid habituation to olfactory and footshock stimuli. To further understand the unique role that D14-3-3? plays in the adult CNS, I mapped the areas in the brain involved in olfactory and footshock habituation. I found that although the mushroom bodies (MBs) are necessary to inhibit premature habituation such as that exhibited by D14-3-3? mutants, D14-3-3? expression specifically in the MBs is not sufficient to rescue premature habituation. Although the loss of either LEO or D14-3-3? appears to cause a deficit in olfactory associative learning, premature habituation is the cause of the deficit seen in D14-3-3? mutants. As leo mutants do not exhibit a premature habituation phenotype, it appears that within the MBs LEO and D14-3-3? are not functionally equivalent. Therefore, the data supports the hypothesis that 14-3-3s have functional specificity and redundancy likely to represent use of homo and heterodimers in different processes within the tissues of an organism.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/2725 |
| Date | 01 November 2005 |
| Creators | Acevedo, Summer Fontaine |
| Contributors | Skoulakis, Efthimios M. C. |
| Publisher | Texas A&M University |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Dissertation, text |
| Format | 1678690 bytes, electronic, application/pdf, born digital |
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