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- Thijs Ettema
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I completed my PhD under the supervision of Dr. Andrew Roger at Dalhousie University (Halifax, Canada) studying the mitochondrial metabolism of diverse unicellular eukaryotes (protists). In particular, I am interested in uncovering the various metabolic adaptations employed by protists to thrive in anoxic environments. The mitochondria of some protists are drastically different than those found in aerobes. For example, hallmark features of mitochondria, including oxidative phosphorylation and the citric acid cycle, are absent. We refer to these organelles as ‘mitochondria-related organelles’ (MROs), since even though they do not resemble the classical ‘powerhouse of the cell’, they are indeed related to mitochondria.
In addition to exploring the metabolic diversity of MROs, I am interested in understanding how this metabolism evolved. Did the common ancestor of mitochondria have the capability of performing both anaerobic and aerobic metabolism? Is some or all anaerobic metabolism secondarily derived? To answer these questions, I explored the evolutionary history of anaerobiosis-related proteins in different protists.
The overall conclusion of my PhD work suggests that many anaerobic features of MROs (such as cofactor biosynthesis, pyruvate metabolism, and ATP generation) were acquired by various protists via lateral gene transfer (LGT) from prokaryotic and eukaryotic sources. Surprisingly, I also observed that many of these laterally acquired proteins seem to interface with existing metabolic pathways thus creating novel systems of mosaic origins. This suggests that, much like prokaryotes, LGT can have a profound impact on the biology of eukaryotes.
The advent of single-cell genomics and transcriptomics have revolutionized modern biology. It has granted us a glimpse of the unculturable microbial ‘dark matter’. In the Ettema lab, I hope to apply this robust technology to answer questions about diverse protist biology. My first initiative in the Ettema lab, in collaboration with Prof. Staffan Svard, will compare the transcriptomes of the fish pathogen Spironucleus salmonicida exposed to different in vivo environments. In this experimental framework, I hope to identify key adaptaions that permit Spironucleus invasion.