Dr. Dawn Hall, Office of the Chief Information Officer, Treasury Board of Canada Secretariat, Government of Canada
When I obtained a PhD in Biology in 2007, I never would have predicted what the next 10+ years of my career would bring. This talk will begin with a retrospective look at my time as a PhD student and post-doc, followed by a description of the career experiences that have followed: from science communication and exhibit content development at the Ontario Science Centre, to exhibit interpretation for the renewal of the Canada Science and Technology Museum, to my current role as an analyst/advisor with the Government of Canada. Throughout, I will discuss the decisions that I made, and how the skills that were developed during my PhD and post-doc were applied in the jobs that have followed. I will also share lessons learned and perspectives from the career journey.
Dr. Louise Winn, Dept of Biomedical and Molecular Sciences, Queen's University
Drugs and environmental chemicals can harm the developing fetus by causing not only the commonly appreciated structural defects such as cleft lip, but also biochemical and functional abnormalities related to alterations in membranes as well as enzymes and other proteins. These compounds can also disrupt normal metabolic and endocrine signalling via epigenetic modifications, including DNA methylation, histone modifications, and/or RNA-mediated silencing of genes through miRNA, resulting in negative health outcomes later-in-life.My research program aims to investigate mechanisms of in utero initiated developmental toxicity employing a combination of expertise in biochemical and morphological assessment of chemical toxicity, and molecular toxicological approaches. Our goal is to answer fundamental mechanistic questions about the biological effects of in utero exposures to drugs and environmental chemicals to inform exposure monitoring practices, policy and human health assessments.
Feb 28, 2019 // Exploration of sustainable Arctic fisheries: microbiomes for bioprospecting and fish health assessments
Erin Hamilton, M. Sc. Candidate
The Towards a Sustainable Fishery for Nunavummiut (TSFN) Project is partnered with the Nunavut community of Gjoa Haven. We are using genomic and microbial analyses to inform strategies to retain genetically-diverse and healthy fish stocks for Inuit communities. In this region, Arctic char (Salvelinus alpinus) and whitefish (Coregonus spp.) can be anadromous, migrating annually from the ocean to freshwater lakes and rivers in order to escape sub-zero temperatures. The fish and their associated microbiomes must adapt accordingly to their changing environment. Analysis of fish microbial community compositions has shown that skin bacterial communities are statistically different when sampled from freshwater or saline water sites, but appear to maintain a core community, with Proteobacteria, Firmicutes, and Cyanobacteria presenting as major phyla. Given these findings, microbial assemblages could be used as a proxy for fish health. In addition, there is bioprospecting potential for microbial taxa that could provide advantages for fish in aquaculture.
Friday, Feb 22, 11:30-12:30 // Temporal changes of Arabidopsis plasma membrane proteome during cold- and de-acclimation
Dr. Matsuo Uemura, Faculty of Agriculture, Iwate University, Morioka, Japan
Freezing stress is one of the most important limiting factors of plant survival. Plants have developed a freezing adaptation mechanism upon sensing low temperatures (cold-acclimation). Compositional changes in the plasma membrane, one of the initial sites of freezing injury, is prerequisite of achieving cold acclimation and have been investigated in several plant species. However, the cold dehardening process at elevated temperatures (de-acclimation) has not yet been fully characterized. Here we conducted shotgun proteomics with label-free semiquantification on plasma membrane fractions of Arabidopsis leaves during cold acclimation and de-acclimation. A list of 873 proteins with significantly changed proteins in response to the two processes was obtained. Although the cold-acclimation-responsive proteins were globally returned to non-acclimated levels by de-acclimation, several representative cold-acclimation-responsive proteins tended to remain at higher abundance during de-acclimation process. Our results suggest that plants deharden right after cold acclimation to restart growth and development but some protein changes of the plasma membrane may be maintained to cope with the threat of sudden freezing during deacclimation process.
Dr. Mark Belmont, University of Manitoba
This seminar will provide insights into the utility of next generation, RNAi-based molecular fungicides and their applicability to control crop pathogens. Sclerotina sclerotiorum, the causal agent of white mold, infects over 450 species of plants worldwide. This fungal phytopathogen has become a major threat to crops including canola which contributes $27 billion to the Canadian economy. Sclerotinia is a persistent problem for canola growers that has traditionally been managed using broad-spectrum fungicides. However, current fungicide strategies have proven to be ineffective. Thus, there is an immediate need to manage Sclerotinia using novel species-specific control methods. Our strategy exploits the inherent cellular defense process known as RNA interference (RNAi). Upon encountering a double stranded RNA (dsRNA) molecule, the cell processes the dsRNA specifically targeting transcripts with sequence homology. Sclerotinia-specific target genes were identified using bioinformatics. RNAi knockdown was confirmed using qRT-PCR on RNA isolated from fungal cultures. Transgenic plants over-expressing the dsRNA showed a profound and prolonged tolerance to Sclerotinia.
Dr. Adam Mott, Dept Biology, Univ Toronto, Scarborough Campus
To thrive, plants must be able to quickly recognize and respond to changing environmental conditions and pathogen attack. The perception of many signals is accomplished through the collective action of members of the leucine-rich repeat receptor kinase (LRR-RK) family, of which there are 225 in Arabidopsis. Upon detection of an extracellular signal, these receptors physically interact to form signaling-competent structures able to integrate complex signals to guide plant defence and growth. Using a high-throughput interaction screen we determined the physical interactions between 200 of the LRR-RLKs from Arabidopsis. Using network analysis and community detection we have detected distinct, but interconnected, subnetworks that show evidence of specialized biological activity and demonstrated novel function for several previous unstudied receptors. In addition, we show that the overall network structure is critical for proper signaling responses, and disruptions can have unexpected consequences at a distance.
Dr. Jacqueline Bede, Dept Plant Science, McGill University
Plant responses to biotic and abiotic stresses require prioritizing different pathways to appropriate regulate metabolic flux. Some caterpillar species have honed into this “cross-talk” and evolved strategies to manipulate plant signaling pathways to minimize induced plant responses. Bede’s lab studies this close, complex interaction from both the plant and insect perspective. Research in her laboratory also investigates how these plant-insect interactions may be influenced by future climatic conditions, in particular elevated atmospheric carbon dioxide.
Nov 22, 2018 // Divide and conquer: the contribution of the divided bacterial genome in conquering multiple niches
Dr. George diCenzo, Dept of Biology, University of Florence, Italy
Approximately 10% of bacterial species contain a genome divided between two or more large (> 300 kb) DNA replicons. One such organism is Sinorhizobium meliloti, a soil-dwelling a-proteobacterium that can enter into N2-fixing endosymbiotic interactions with leguminous plants. A synthetic genome reduction approach was used to construct a S. meliloti derivative lacking both of its secondary replicons, which together encode 2900 genes. High-throughput growth assays and soil mesocosm experiments demonstrated that the secondary replicons likely have small contributions to growth in bulk soil despite encoding a broad range of metabolic capabilities. Instead, in silico modelling of S. meliloti metabolism suggested that the metabolic properties of the secondary replicons are associated with specific environments, such as the rhizosphere. Consistent with this being a generalizable property, comparative genomics of ~300 strains from the family Burkholderiaceae suggested that their secondary replicons are enriched in environmental adaptation genes. Nevertheless, massively-parallel transposon-sequencing uncovered extensive genetic interactions between the S. meliloti replicons. Similarly, transcriptomics (RNA-seq) and non-targeted metabolomics illustrated that the more conserved secondary replicon of S. meliloti has become integrated into the general metabolic and transcriptomic networks of the cell. This integration is due, at least in part, to the transfer of core genes from the chromosome to the secondary replicon. Overall, these systems-level data support a model in which large secondary replicon(s) provide increased genome flexibility, facilitating more rapid adaptation to novel environments. These results can have implications in elucidating the genomics of host-adaptation, which is applicable to the many human pathogens and plant symbionts that harbour divided genomes.
Dr. T. Ryan Gregory, Dept. Integrative Biology, Univ of Guelph
The extraordinary diversity in genome sizes (haploid nuclear DNA contents, or “C-values”) among eukaryote species has remained a major puzzle in genetics for over 60 years. The size of a genome size bears no relationship to the number of coding genes it contains or to the complexity of the organism in which it is found, a finding so surprising to early researchers that it became known as the “C-value paradox”. While the discovery of non-coding DNA has solved this paradox, it has raised a series of new questions regarding the origins, mechanisms of spread and loss, phenotypic consequences, and reasons for differential abundance of non-coding DNA in different species. This seminar explores these questions, with a particular emphasis on the connection between genome size and such important phenotypic characteristics as cell size, body size, metabolism, and development in animals.
Dr. Nicole Templeman, Lewis-Sigler Institute for Integrative Genomics & Dept. of Molecular Biology, Princeton University.
Since most biological processes require nutrients, signaling networks that respond to nutrient levels play important roles in regulating many functions, including growth, reproduction, and tissue maintenance with age. In organisms ranging from invertebrates to mammals, genetic loss-of-function of signaling components in nutrient-sensing pathways—such as the insulin/insulin-like growth factor-1 signaling (IIS) pathway—can thereby slow the physiological deterioration that characterizes aging, and extend lifespan. In Caenorhabditis elegans, loss-of-function of the daf-2 IIS receptor also significantly delays the age-related decline in reproductive capacity, one of the earliest hallmarks of aging. To identify mechanisms that directly control aging of the reproductive system, we compared the transcriptomes of aged daf-2(-) and wild-type oocytes. Remarkably, inhibiting one group of oocyte-specific IIS transcriptional targets, cathepsin B cysteine proteases, can improve oocyte quality in aging C. elegans, even when inhibition takes place partway through the reproductive period. This suggests that it is possible to slow age‑related reproductive decline with mid‑life interventions. In addition to evaluating molecular changes downstream of key nutrient-sensing signaling networks like the IIS pathway, I am interested in determining whether we can uncover new mechanisms of age-related decline by looking at other major regulators of growth, energy balance, and metabolism. The cAMP response element-binding protein (CREB) is a highly conserved transcription factor that regulates numerous processes, including growth and nutrient storage. I found that in C. elegans, CREB also regulates oocyte quality and reproductive capacity with age, which is a previously unknown function of CREB signaling. Interestingly, this targeted effect on reproductive aging is due to CREB’s activity in the C. elegans hypodermis, an epithelial tissue transcriptionally similar to mammalian liver and adipose tissue. Collectively, these projects have revealed some of the intricacies by which tissue-specific signaling events exert nuanced effects on complex systemic functions, and uncovered new mechanistic regulators of age-related decline.