Effects of Domino Mutations on Cell Proliferation in the Drosophila Eye Pubblico

Abstract

Domino is a critical component of the Notch signaling pathway, which regulates cell proliferation. Domino has also been implicated as a Notch-independent regulator of cell proliferation in the Drosophila eye. Recently, it was reported that domino may be pleiotropic for cell proliferation in the wing, such that both domino loss-of-function and gain-of-function mutations enhance nicking in the wing margin. In the present study, domino mutant strains, over-expression strains, and RNAi strains were crossed to an eye hyperproliferation strain (GMR-YkiS168A) in order to determine whether domino behaves the same way in the eye as it has previously been reported to behave in the wing. Notch loss-of-function and gain-of-function mutants were also crossed to the eye hyperproliferation strain. Offspring of the crosses were analyzed for visually-scoreable phenotypic differences, differences in penetrance, and for statistically significant differences in eye size compared to controls. The offspring from both sets of crosses were compared to each other in order to determine whether phenotypes created by the different domino strains might be due to Domino's interactions with Notch.

We found that two domino RNAi strains and one domino over-expression strain showed suppression of the hyperproliferation eye phenotype, but that the remaining strains did not show consistent, statistically significant differences either in eye size or in the penetrance of the hyperproliferation phenotype compared to control crosses. Notch loss-of-function strains also showed suppression of proliferation when crossed to w¹¹¹⁸ (wild-type) or GMR-GAL4 (over-expression of the enhancer GAL4 in the eye) flies. Notch gain-of-function mutations were lethal when crossed to GMR-YkiS168A. When Notch loss-of-function mutants were crossed to GMR-YkiS168A, the resulting offspring had different eye phenotypes than those of the GMR-YkiS168A x domino experimental strains, suggesting that Domino's effects on cell proliferation may be independent of Notch.

It is not possible to definitively conclude that domino behaves the same way in the eye tissue as it does in the wing tissue. Our results that domino loss-of-function and domino gain-of-function suppress hyperproliferation in the eye, however, are congruent to previous observations that domino RNAi and domino over-expression strains both enhance a hypo-proliferation phenotype in the wing.

Table of Contents

Introduction...........................................................................................1

Methods.................................................................................................7
i) Genetic crosses...................................................................................7
ii)Drosophila strains...............................................................................8
a) The Domino Modifier Genetic Analysis......................................................8
b) Test for Environmentally Caused Variations in Eye Size..............................10
c) Genetic Crosses with GMR-YkiS168A and Domino Mutant Strains.................10
d) Genetic Crosses with GMR-YkiS168A and Notch Mutant Strains...................12
iii) Data collection..................................................................................12
a) Scoring for Wing Nicks...........................................................................13
b) Scoring for the Yorkie Eye Phenotype.......................................................14
iv) Data analysis.....................................................................................14

Results...................................................................................................16
i) The Domino Modifier Genetic Analysis.................................................16
ii) Test for Environmentally Caused Variations in Eye Size......................19
iii) Genetic Crosses with GMR-YkiS168A and Domino Mutant Strains......21
iv) Genetic Crosses with GMR-YkiS168A and Notch Mutant Strains.........28

Discussion..............................................................................................31

Conclusion..............................................................................................38

References..............................................................................................40

About this Honors Thesis

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School	Emory College
Department	Biology
Degree	BS
Submission	Honors Thesis
Language	English
Research Field	Biology, Genetics Biology, General
Parola chiave	Drosophila Yorkie (Yki) Domino Hyperproliferation Mastermind (Mam) Notch
Committee Chair / Thesis Advisor	Yedvobnick, Barry, Emory University
Committee Members	Beck, Christopher, Emory University Moberg, Kenneth H, Emory University

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