Enlightening the dark origin of eukaryotes
- Reference number
- FFL12-0024
- Start and end dates
- 140101-191231
- Amount granted
- 9 700 000 SEK
- Administrative organization
- Uppsala University
- Research area
- Life Sciences
Summary
The origin of the eukaryotic cell represents an enigmatic yet dramatically incomplete evolutionary puzzle. Whereas evidence is mounting in support of a fusion-like event at the basis of eukaryotic life, the emergence of typically eukaryotic features such as the nucleus and other endomembrane systems is poorly understood, and subject of heated debate. Although larger eukaryotes such as plants, animals and fungi dominate our visual landscape, the bulk of the diversity of eukaryotic life is microbial in nature: the protists. The genomic exploration of the largely unmapped diversity of protists has the potential to uncover important details of the origin and evolution of eukaryotes. Yet, such studies have thus far been unfeasible due to biological and technological limitations. In the current proposal, I will utilize a novel culture-independent approach that will overcome these limitations, and obtain molecular sequence data from individual environmental protist cells in a high-throughput setting. The obtained data will be analyzed using advanced phylogenomic and comparative genomic frameworks. The proposed study (i) is expected to reveal important insights in the evolution of eukaryotic gene content, (ii) will provide sufficient taxonomic sampling that is needed to confidently identify the root of the eukaryotic tree of life, and (iii) has the potential to uncover completely novel branches in the tree of life, some of which might represent missing links in eukaryotic evolution.
Popular science description
Enlightening our dark past 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 somehow emerged from these microbial cells in a process that is currently poorly understood by scientists. The current research proposal aims to gain new insights in this process by studying unicellular cousins of complex life forms known as ‘protists’. Protists are important for several important processes that occur in Nature, such as the cycling of minerals in the oceans, and they also comprise numerous alga species that produce much of the oxygen that we use to breathe. The protist world is vastly diverse and remains poorly studied, and the rationale of studying these ‘simple complex cells’ is therefore that they likely still contain characteristics of the birth process of complex cell types. The present study will collect protists from allover the world, even at places where one would not expect life to be possible perhaps, such as the bottom of the ocean, and close to sites that are volcanically active. The idea behind this is that such hostile environments might resemble places where such complex life might have originated a long time ago. The protists that will be retrieved from these and other places will be studied with a novel type of technology that allows one to decipher the genetic material of individual protist cells. This revolutionary technology, referred to as ‘single cell genomics’, will be used to investigate large numbers of protists that are completely new to humankind. After the genetic material of these individual protists has been determined, it will be compared to that of complex organisms, including us humans, but also to simple organisms such as bacteria. These comparisons will reveal important details of the transition from simple to complex life forms, and about the processes have been important in this transition. As such, our dark past might become a little bit clearer.