Joran Martijn, Post Doctoral Fellow

Hi! I’m a new post-doc in the lab of Andrew Roger and I officially started in August 2019. The goal of my research here is to study the evolutionary histories of the Metamonada, a group of anaerobic protists, and their mitochondria. More on that below. Other than the biological aspect of this project I’m particularly fascinated by the methods by which we can study these evolutionary histories. These include the very latest DNA sequencing technologies and the continuously evolving bioinformatics algorithms. These algorithms allow us to amongst other things assemble entire genomes de novo and reconstruct the evolutionary histories of the genes they encode. Being from the Netherlands, I did most of my undergraduate studies in Rotterdam (bachelors) and Utrecht (masters), focusing primarily on molecular and cellular biology. In 2012 I moved to Uppsala, Sweden and started my PhD studies at the -just founded- lab of Thijs Ettema, in the field of in evolutionary microbiology. I learned bioinformatics and used metagenomics and single-cell genomics to discover and reconstruct genomes from completely unexplored branches of the tree of life. In particular, we assembled genomes from many novel lineages of Alphaproteobacteria and used those to study the alphaproteobacterial ancestry of mitochondria. See https://www.the-scientist.com/daily-news/mitochondrias-bacterial-origins-upended-33345 for a popular science article describing the work. In 2017 I obtained my PhD degree and decided I would like to continue my research in the lab of Andrew Roger. I managed to get funding through the Swedish ‘VR International Postdoc’ grant and arrived in Halifax in August 2019.

Research interests:

The Metamonada are a clade of anaerobic protists for which the exact phylogenetic position in the tree of life remains unclear. The most well known metamonads are perhaps Trichomonas vaginalis, the causative agent of sexually transmitted trichomoniasis, and Giardia intestinalis, the causative agent of gastrointestinal tract disease giardiasis. They additionally include Monocercomonoides, the very first organism discovered that has completely lost its mitochondria. Compared to typical aerobic organisms like humans, yeast and plants, the metamonads house substantially reduced mitochondria called mitochondria related organelles (MROs). They differ most notably in their mode of ATP production: whereas aerobic mitochondria execute oxidative phosphorylation, MROs often use anaerobic substrate level phosphorylation. The exact pathways differ between most metamonad species. The aim of the project is to infer the complete evolutionary history of the metamonads and identify all gene gains and losses that occurred on branches associated with important evolutionary transitions such as (i) the switch to anaerobic lifestyle, (ii) adaptation to host-associated lifestyle and (iii) reduction and complete loss of mitochondria. We do this by sequencing the complete genomes and transcriptomes of novel Metamonads with a mix of Oxford Nanopore and Illumina sequencing and compare them with the publicly available genomes and transcriptomes with the latest bioinformatics algorithms.

You can reach Joran at:

Work Phone: (+1) 902-494-2881
Fax: (+1) 902-494-1355
E-mail: joran{dot}martijn{at}dal{dot}ca