Asgard archaea may link archaea to complex life

Researchers have discovered a new group of microbes called Asgard archaea, which may hold important clues about the origins of complex life forms. These microorganisms were first identified in 2015 from gene fragments found in deep-sea sediments, leading to the assembly of their complete genome. Asgard archaea, named after a location near a black smoker called Loki's Castle, are a separate subgroup of archaea. Like bacteria, they are single-celled, but genetically they are different. Recent studies suggest that Asgard archaea may be closely linked to eukaryotes, the group that includes plants and animals, possibly leading to a reevaluation of how we categorize all life on Earth. Researchers at ETH Zurich have been studying Asgard archaea, focusing on Lokiarchaeum ossiferum, which was isolated from Slovenian sediments. They found that this microorganism has structures similar to those in eukaryotes, including a protein named Lokiactin, which plays a role in cell structure. The researchers also discovered tubulin proteins in Asgard archaea, which form microtubules similar to those found in eukaryotic cells. Despite the interesting findings, not all questions about Asgard archaea have been answered. The presence of tubulins is rare among these microbes, and scientists are still trying to understand their function. The researchers believe that the cytoskeleton, which includes structures like actin and microtubules, was crucial for the evolution of complex life. The team plans to continue their research by examining the role of actin and tubulin in Asgard archaea and identifying proteins on these microbes' surfaces. This work could help scientists learn more about how these ancient organisms are linked to the development of eukaryotes and their unique biology.