Welcome to the Ettema-Lab!
We live in a world that is dominated by microbial life. Despite that this ‘unseen majority’ drives major biochemical cycles on our planet, the extent of the molecular and functional diversity of these prokaryotes and protists has been poorly mapped. One important reason for this is that only about 1% of all microbial species can be cultured under laboratory conditions. In the recent years, culture-independent methods, such as metagenomics and single cell genomics have been developed that allow for the genomic exploration of this so-called ‘microbial dark matter’. The ongoing research in the Ettema-Lab aims to:
- Explore microbial diversity using novel cultivation-independent approaches, such as metagenomics and single cell genomics.
- Gain insight in the evolutionary relation between the Three Domains of Life, the Archaea, Bacteria and the Eukarya using various phylogenomic approaches.
- Reconstruct the origin and evolutionary history of the eukaryotic cell by comparative and phylogenetic analyses of prokaryotic and eukayotic genome content.
Exploration of the microbial world
One of the main activities in the Ettema-Lab is to explore the existing microbial diversity on our planet. In particular, we are interested in a relatively understudied branch in the Tree of Life, that of the Archaea. The discovery of the Archaea, also referred to as the Third Domain of Life, by Carl Woese and George Foxrepresents a milestone in the modern era of microbiology. During the past few decades, the independent status of the Archaea has been confirmed, pointing out that they represent an independent branch in the Tree of Life with distinct biochemical and biological characteristics. Yet, with respect to the overall diversity and evolutionary status of the Archaea, much remains to be discovered. Currently, we are exploring several environmental samples retrieved from allover the world -ranging from hydrothermal vents in Japan to hot springs in Yellowstone National Park and New Zealand – for the presence of novel archaeal (and bacterial) lineages using cultivation-independent approaches, such as metagenomics and single cell genomics.
The origin of the eukaryotic cell
Apart from all visible life that surrounds us (humans, animals, plants, fungi, etc), a vast unseen world exists that comprises of microscopically small organisms: microbes. These microbes, also referred to as ‘prokaryotes’, are relatively simple life forms, in contrast to the complex cells that we, humans, are comprised of. Ironically, or rather intriguingly, about 2 billion years ago, these complex cells emerged from a fusion of 2 types of microbial cells. The identity of these cells however, remains to be a mystery to date. The Ettema-Lab aims to trace the identity of these ‘microbial ancestors’ of complex life on our planet using novel, revolutionary technology, in order to gain substantial insights in how complex life originated. One of the main findings that we have obtained thus far, is that the eukaryotic lineage seem to branch from within the archaeal Domain of life, affiliating with the so-called ‘TACK’ superphylum (comprising Thaum-, Aig-, Cren- and Korarchaeota). This finding is consistent with the recent discovery with several ‘eukaryotic’ signature genes in these archaeal lineages, including genes encoding proteins such as actin, tubulin, and several proteins involved in transcription and membrane deformation.
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