MSc Exit Seminar
Friday, July 19th, 2019 at 10:10am – Ramsay Wright Building, Room 432
Gabriele Nandal (Buck Lab)
Characterization of Sirtuin 3 and Targets in the Western Painted Turtle
The western painted turtle (Chrysemys picta) is a champion anaerobe capable of surviving months with little to no oxygen. This species’ anoxia tolerance is enabled by many physiological and biochemical adaptations; metabolic depression is perhaps one of the most useful mechanisms that enables the turtle’s survival. In response to anoxia the turtle can suppress its metabolic rate by 90%, this tolerance is partly achieved through downregulation of both protein synthesis and activity in order to minimize ATP demand. Cellular functioning can then be modulated through an ATP-inexpensive, reversible, and rapid post-translational protein modifications. Cellular metabolism is highly regulated by reversible-acetylation of the mitochondrial proteome, however it is relatively unexamined in the anoxia-tolerant turtle. In the mitochondria, Sirtuin 3 (SIRT3) is the global deacetylase, and is involved in many cellular processes such as metabolic regulation and stress resistance. This thesis shows that while the turtle exhibited increases mitochondrial acetylation during early anoxia in the brain and liver, concomitantly SIRT3 protein levels were also elevated. In addition, Cyclophilin D levels, a direct target of SIRT3, were also shown to be elevated during anoxia. Another target of SIRT3, p65 subunit of NF-kB exhibited increased deacetylation during anoxia and reoxygenation in the brain. While no difference in prevalence or activity of manganese superoxide dismutase, an antioxidant target of SIRT3, was observed either during anoxia or reoxygenation. Overall, this thesis provides the first evidence that SIRT3 and mitochondrial proteome acetylation may play a role in the regulation of anoxia in the painted turtle.
MSc Exit Seminar
Tuesday, August 7, 2018 at 1:10 pm SW -403, University of Toronto at Scarborough
Chun Hua Wei (Hasenkampf Lab)
The role of HOP2 in Homologous Recombination in Arabidopsis thaliana
The purpose of this study was to investigate the role of HOP2 protein in non-meiotic cells in Arabidopsis. HOP2 is already known to be important to meiotic chromosome pairing and homologous recombination, yet the role of HOP2 outside of meiosis is far from being fully elucidated. My study focused on the mitotic chromosome events with and without the application of radiation. In the absence of radiation, no fragments and chromatin bridges were found in hop2-1 plants, but they did seem to experience a modest chromosome separation delay. When irradiated, both genotypes had significant decreases of mitotic indices and increases of bridges. The decreases in mitotic indices were comparable for the two genotypes, suggesting they accomplish repair at similar rates. Irradiated hop2-1 had significantly more mis-repaired breaks, as determined by the bridges. My findings suggest that HOP2 is also important for the fidelity of the exchange process in non-meiotic HR repair.
MSc Exit Seminar
Tuesday, May 29, 2018 at 2:10pm CCT -3000, University of Toronto at Mississauga
Delara Dadsepah (Levine Lab)
Anatomical and Behavioural Characterization of Dpr-Interacting Protein Beta in Drosophila melanogaster
The mammalian limbic system has many important biological functions. During development, the limbic-system associated membrane protein (LSAMP) plays a crucial role by ensuring proper neuronal connectivity within the system. Similarly, the LSAMP homologue in the Drosophila, the Dpr-interacting protein beta (DIP-β), is believed to assist in neuronal formation during the development of the fly central nervous system. Other data suggests that DIP-β even regulates social interactions. Researchers have only more recently begun investigating DIP-β however, and DIP-β remains to be extensively studied. Thus, the aim of this project was to fully characterize DIP-β expression in the brain and the behaviour of DIP-β mutants, to obtain a better understanding of DIP-β function. DIP-β’s predominant expression in the optic lobes and regions in the central brain, along with changes in behavioural rhythmicity observed in DIP-β mutants, suggests DIP-β may be associated with clock mechanisms.