Lokiarchaeota and the Evolution of Complex Cellular Life

In summary, biologists have categorized life into two main groups: prokaryotes and eukaryotes. Prokaryotes are simpler single-celled organisms, while eukaryotes are more complex and contain specialized compartments. A new species of archaea, called Lokiarchaeota, has been discovered and is the closest known relative of all eukaryotes. This finding sheds light on the evolutionary origins of many eukaryotic features and supports the idea that eukaryotes evolved from a type of archaea. However, further research is needed to fully understand the evolution of other unique eukaryotic traits.
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Biologists split life into two broad categories: prokaryotes and eukaryotes. Prokaryotes are relatively simple single-celled organisms and are split into two groups (bacteria and archaea). Eukaryotes, on the other hand, are much more complex cells containing specialized compartments such as the nucleus, mitochondria, and other membrane-bound organelles. All of what we consider complex life (e.g. plants, animals, fungi, protists) are eukaryotes. Scientists have long been interested in determining how eukarotes evolved from prokaryotes.

This week, researchers published the discovered a new species of archaea which shares many features with eukaryotes and is the closes known prokaryotic relative of all eukaryotes. The finding explains the evolutionary origins of many features once thought to be unique to eukaryotes, and strengthens the "two-domain" hypothesis of life:
The origin of the eukaryotic cell remains one of the most contentious puzzles in modern biology. Recent studies have provided support for the emergence of the eukaryotic host cell from within the archaeal domain of life, but the identity and nature of the putative archaeal ancestor remain a subject of debate. Here we describe the discovery of ‘Lokiarchaeota’, a novel candidate archaeal phylum, which forms a monophyletic group with eukaryotes in phylogenomic analyses, and whose genomes encode an expanded repertoire of eukaryotic signature proteins that are suggestive of sophisticated membrane remodelling capabilities. Our results provide strong support for hypotheses in which the eukaryotic host evolved from a bona fide archaeon, and demonstrate that many components that underpin eukaryote-specific features were already present in that ancestor. This provided the host with a rich genomic ‘starter-kit’ to support the increase in the cellular and genomic complexity that is characteristic of eukaryotes.
Sprang et al. 2015 Complex archaea that bridge the gap between prokaryotes and eukaryotes Nature. Published online 06 May 2015. http://dx.doi.org/10.1038/nature14447

See also this summary from National Geographic: http://phenomena.nationalgeographic...robe-is-closest-relative-to-all-complex-life/

Although this finding answers many questions about the evolution of eukaryotes, more work remains to be done to understand the evolution other features unique to eukaryotes, such as the evolution of the nucelus. However, because eukaryotes evolved from these "Loki" archaea after they endosymbioticallly captured an alphaproteobacterium, it would be a neat experiment to try to recreate this event in the lab.
 
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Nice news summary. Thanks for sharing.
 

Related to Lokiarchaeota and the Evolution of Complex Cellular Life

1. What is Lokiarchaeota?

Lokiarchaeota is a group of single-celled microorganisms that belong to the domain Archaea. They were first discovered in 2010 in the deep-sea sediment of the Loki's Castle hydrothermal vent field in the Arctic Ocean.

2. How does Lokiarchaeota contribute to the evolution of complex cellular life?

Lokiarchaeota is believed to be one of the earliest branches of the tree of life, and their discovery has provided important insights into the origins of complex cellular life. They possess some key genes that are also found in eukaryotes, such as those involved in the formation of the cell membrane and the cytoskeleton. This suggests that they may have played a role in the evolution of these essential cellular structures.

3. What is the significance of the discovery of Lokiarchaeota?

The discovery of Lokiarchaeota has challenged the long-held belief that eukaryotes evolved from a fusion of archaea and bacteria. It has also shed light on the possibility of a more complex and diverse microbial world in the deep-sea, as well as the potential for these microbes to play a role in the evolution of complex life on Earth.

4. How do scientists study Lokiarchaeota?

Scientists study Lokiarchaeota through metagenomic sequencing, which involves analyzing the genetic material of environmental samples. They can also isolate and culture these microorganisms in laboratory settings to better understand their physiology and behavior.

5. What other potential implications does the study of Lokiarchaeota have?

Studying Lokiarchaeota may have implications beyond the evolution of complex cellular life. Their unique genetic makeup and ability to thrive in extreme environments could also have potential applications in biotechnology, such as the production of enzymes for industrial processes or the development of new antibiotics.

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