LE3 .A278 2018

2018

Gibson, Glenys

Acadia University

Bachelor of Science

Honours

Biology

Biology

The Epidermal Growth Factor Receptor (EGFR) signalling pathway is of interest to studies of cardiac development and disease due to its integral role in the cell life cycle. The Drosophila melanogaster heart is a good model for studying cell specification as its structure is similar to the early embryonic vertebrate heart at the functional and molecular level. This study investigated factors of the EGFR signalling pathway and the downstream Ras-Mitogen-Activated Protein Kinase (RAS/MAPK) signalling pathway to better understand their roles in heart cell specification. One objective was to generate DNA constructs of a dominant negative allele of the RAS/MAPK factor, Son of sevenless (Sos), and a control. The other objectives of this study were to investigate the role of the EGFR ligand Vein and to test the hypothesis that apoptosis played a role in the loss of a specific subset of cardioblasts, termed generic cardioblasts, in EGFR mutants. DNA was extracted from embryos with the Sos dominant negative mutation and control adult flies. The control sequence was PCR amplified and cloned. However, amplification of the mutant sequence was unsuccessful. Vein mutants and flies harbouring a deficiency that includes the vein gene were crossed and the progeny visualized using immunofluorescent antibody staining and the confocal microscope. An in situ hybridization against vein mRNA was attempted but unsuccessful. Apoptosis was inhibited in the mesoderm of EGFR mutants of the protein Star through overexpression of the apoptosis-inhibitor p35 using the UAS/GAL4 system. The number of cardioblasts in Star mutants with and without apoptosis inhibition was compared using immunofluorescent antibody staining, the confocal microscope and statistical analysis. Major findings were that a significant rescue of generic cardioblasts was observed in Star mutants with apoptosis inhibited and that vein mutants possessed the wild type phenotype. These results indicated that apoptosis has a role in the loss of generic cardioblasts in Star mutants and that vein does not have a major role in heart cell specification. These findings help to further elucidate the role of EGFR signalling in heart cell specification.

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https://scholar.acadiau.ca/islandora/object/theses:2696