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.
MSc Exit Seminar
Tuesday, May 29, 2018 at 10:10pm, SW 403- University of Toronto at Scarborough
Peilu Gan (Hasenkampf Lab)
The Role of the Arabidopsis Hop2 Protein in Promoting Homologous Chromosome Interactions and Blocking Nonhomologous Interactions
The Homologous Pairing Protein 2 (Hop2) is important for its role in reciprocal genetic exchange in meiosis. It is thought to operate as a part of the double-strand break (DSB) repair pathway. Recent models give two potential roles for Hop2: it acts to promote interactions between homologous chromosomes, or it acts to block interactions between non-homologous chromosomes. The goal of my study was to see if the Hop2 protein acted to block non-homologous interactions by analyzing its role in haploid plants. Haploid hop2-1 mutants were analyzed by light and fluorescent microscopy and compared with haploid WT plants. Like WT haploids, hop2-1 mutants showed univalents in early meiosis. However, unlike WT haploid plants, hop2-1 haploid mutants showed large amounts of DNA fragmentation and chromosomal bridging in anaphase and metaphase for both Meiosis I and Meiosis II. This suggests that Hop2 acts to block non-homologous interactions.
MSc Exit Seminar
Friday, May 11th, 2018 at 10:10am Earth Sciences Building, Room 3087
Van Phan (Yoshioka Lab)
Evaluation of GCaMP3 Protoplasts for the Analysis of Ca2+ Signaling in Plant Immunity
Cytoplasmic calcium [Ca2+]cyt elevation is an early event that occurs after recognition of various environmental stimuli. Utilization of Ca2+visualization tools such as genetically-encoded Ca2+ indicators has advanced our knowledge of the temporal and spatial nature of Ca2+ signals. GCaMP3 is a green fluorescence protein (GFP)-based genetically-encoded indicator that can be detected by a conventional fluorescence microscope and a plate reader system. In this study, the use of GCaMP3 to study plant Ca2+ signals in protoplasts was evaluated.
Firstly, Arabidopsis thaliana leaf mesophyll protoplasts derived from stable transgenic lines expressing GCaMP3 were evaluated in comparison to leaf discs. Using fluorescence microscopy and a plate reader, Ca2+ signals upon abiotic and biotic stimuli in protoplasts were assessed in a quantitative and qualitative manner. Ca2+signals upon various stimuli were detected by both microscope and a plate reader. Ca2+ signals detected in protoplasts were generally quicker and stronger than those in leaf discs. However, the signal patterns were fundamentally similar between protoplasts and leaf discs. Thus, it was concluded that protoplasts expressing GCaMP3 can be utilized to study Ca2+ signaling.
Next, the usage of the transient expression of GCaMP3 in protoplasts (by transfection) was tested. This can be a powerful tool to analyze Ca2+signals in various mutants. Several methods to detect Ca2+signals from GCaMP3-transfected protoplasts were evaluated utilizing the bacterial elicitor, flg22. However, the detection by a plate reader was not successful, likely due to the insufficient number of the cells expression GCaMP3 by transfection, while some signals could be observed in individual protoplasts under the microscope.
Taken together, protoplasts can be used for investigating Ca2+signals upon various stimuli using GCaMP3. However, further optimization of the protocol for transfection is required.