MSc Exit Seminar – Cassandra Marie D’Amata – Wednesday, September 27th, 2017

MSc Exit Seminar

Wednesday, September 27, 2017 at 10:10 am, Ramsay Wright Building, Room 432

Cassandra Marie D’Amata (Tropepe Lab)

Characterizing the role of ice1 in maintaining zebrafish neural stem cells


Maintenance of neural stem cell (NSC) niches is required for the continued growth of the zebrafish retina and forebrain after embryogenesis. The zebrafish mutant kess564, which maps to the ice1 locus, exhibits reduced NSC niches. RNA polymerase II-dependent snRNA transcription requires the little elongation complex (LEC) for which ICE1 is an essential scaffolding component. Mutant NSCs which are normally active no longer express markers of cycling cells and become apoptotic. Furthermore, quiescent NSCs of the mutant retina are unable to proliferate in response to UV lesion. Whole-transcriptome analysis of ice1 mutant larvae show a downregulation of CNS and cell cycle genes, and an upregulation of splicing genes indicative of a possible compensatory mechanism. snRNA production appears to be unaffected in a subset of NSCs but reduced in differentiated neurons. This work demonstrates that ice1 is essential for NSC maintenance in an in vivo loss of function model.


MSc Exit Seminar – Stefan Vujadinovic – Monday, September 25th, 2017

MSc Exit Seminar

Monday, September 25, 2017 at 11:10 am, Ramsay Wright Building, Room 432

Stefan Vujadinovic (Tepass Lab)

The Okapi (Oka) FERM Domain Protein Regulates Somatic Stem Cell Numbers and Cell Intercalation during Drosophila Oogenesis


Okapi (Oka) is a Drosophila melanogaster FERM domain protein that is essential for oogenesis. oka (CG34347) null mutants are viable but display multiple defects during oogenesis. Mutant ovaries showed greatly enlarged and multilayered interfollicular stalks, compromised follicular epithelia, and germline disorganization, leading to reduced female fertility. I generated both endogenously and exogenously GFP-tagged Oka protein to examine the distribution of Oka.

Oka was present is all somatic cells of the ovary and localized to adherens junctions (AJs) in the germarium and follicles, including the cap cells, follicular epithelium, intercalating cells that form the interfollicular stalk, and in the migrating border cell cluster and centripetal cells. I also found that oka mutant ovaries contain an increased number of follicle stem cells, a defect that could explain the increased somatic cell numbers observed, and is reminiscent of the phenotypes of several overactive signalling pathways such as Hippo and Hedgehog. Examination of a series of five oka alleles that display different phenotypic strength suggest that interfollicular stalk formation is more sensitive to the reduction in Oka function than other observed defects. Together, my findings suggest that Oka is a component of AJs that negatively regulates follicle stem cell numbers and is required for the intercalation of interfollicular stalk cells.

MSc Exit Seminar -Paige Homme (McMillen Lab)

MSc Exit Seminar

Thursday, September 14, 2017 at 12:10 pm, DV3129- University of Toronto at Mississauga

Paige Homme (McMillen Lab)

“Whole-cell regenerating ‘microbead’ to capture disease antibodies using the yeast species, Pichia pastoris”


Guiding appropriate medical treatment and population surveillance are a few examples of the crucial functions of diagnostics in health care [1]. Antibody based assays are routinely employed, however, they often require substantial resources limiting their use in low-resource settings. Richard Kil and others in Prof. David McMillen’s lab proposed a synthetic biology solution: using yeast as `microbeads’ to detect Chagas disease and dengue antibodies. The yeast diagnostic combines yeast surface display and agglutination. Surface display engineers yeasts natural cell wall linked proteins to display antigens. The cells are placed in a u-shaped well settle into a dot at the bottom by default. Disease specific antibodies bridge the cells causing them to agglutinate; distinguishable by the naked eye. Preliminary work utilized Saccharomyces cerevisiae and I rebuilt the biosensor using an alternative yeast species, Pichia pastoris. It is an industrially viable yeast species that thrives in high-density bioreactors [2]; I investigated the viability of using P. pastoris.