Thompson Rivers University
Thompson Rivers University

Abstracts & Biographies

Fall 2017

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Presenter: Dr Sofie Thijs

Date:  October 5, 2017

Title: Genomics-enabled discoveries of bacteria to fight explosives pollution

Abstract:  

Soils contaminated with explosives due to ordnance decommissioning, manufacturing and use, is a common issue worldwide. Trinitroaromatic explosives are of concern due to their toxicity, mutagenicity and carcinogenicity. An effective, sustainable and economic remediation alternative for ‘dig and dump’ remediation is phytoremediation, the use of plants and bacteria to remove pollutants from soil. Trinitrotoluene (TNT), is recalcitrant to degradation, and advanced tools are required to mine soils for novel degradative bacteria and better exploit phytoremediation at explosives contaminated sites. Genomic, physiological and analytical data will be presented characterizing the microbial communities at a 100-year old TNT-contaminated site, a site where we went to search for bacteria with interesting genes for TNT-degradation. Further, the construction of a collection of genotyped bacteria with degradative and plant-growth promoting properties will be discussed. Field tests showed a significant effect of TNT on soil microbiota diversity and composition, both in the non-vegetated bulk soil and in the rhizosphere of young sycamore samplings. Key-species enriched in TNT polluted soil were identified, and a draft genome for Raoultella ornithinolytica strain TNT was prepared, from which a homolog of the Old Yellow Enzymes (OYE), an enzyme able to liberate nitrite from TNT, was identified and characterized. Metagenome libraries are being used to search for additional OYE homologues. Mesocosm experiments showed a positive effect of inoculating OYE-containing microbes in the rhizosphere of grasses, with significant effects on TNT-transformation rate, plant biomass and health. Genomics-enabled microbial enrichments is paving the way for microbe-stimulated phytoremediation for military site restoration.

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 Presenter: Dr. Gina DiLabio

Date: October 12

Title:  A New View of the Role of Quantum Effects in Radical Enzymes

Abstract:

Radical enzymes are a large class of enzymes that make use of highly reactive radicals to affect thermodynamically challenging chemistry. These proteins generate primary carbon-centred radicals in their active sites which initiate difficult chemistry by abstracting a hydrogen atom from a substrate molecule. But how does the enzyme prevent the radical from abstracting a hydrogen atom from the protein itself and damaging it irreparably? Our preliminary quantum mechanical simulation work has revealed that radical enzyme active sites may have evolved to control the reactivity of radicals using the little known and poorly understood quantum Coulombic effect (QCE). When away from the substrate, the QCE alters the electronic configuration of the radical to a non-Aufbau arrangement, rendering it far less reactive. When the radical is close to the substrate, the QCE is “turned off” restoring the reactivity of the radical. In this presentation, I will discuss the QCE and our findings to date on the role of the QCE in radical enzymes.



Presenter: Dr. Jianping Xu

Date:  October 26, 2017

Title: Fungal Mitochondrial Inheritance: from natural population surveys to laboratory investigations and back

Abstract: 

Mitochondria are essential organelles in eukaryotic cells. It's generally believed that mitochondria are inherited from a single parent, predominantly the maternal parent. However, most studies on mitochondrial inheritance have been on plants and animals. In this presentation, I will show a diversity of fungal mitochondrial inheritance patterns and describe how they differ from those in plants and animals. I will describe how an accidental finding from the last century has led us to a journey full of surprises and to identifying a model from which to further test the molecular mechanisms and evolutionary hypotheses about the potential costs and benefits of uniparental and biparental mitochondrial inheritance.

 


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