Cultivating the Ancestors… in Motion What electron microscope images hint at, but can only be seen in videos: how 'Asgard' archaea move.

Cultivating the Ancestors… in Motion

What electron microscope images hint at, but can only be seen in videos: how 'Asgard' archaea move.

BBC Radio 4 - In Our Time, Archaea How a discovery in the 1970s changed the theory of the origin of complex life on earth.

Available now on BBC radio "In our time: Archaea" with Christa Schleper, Thorsten Allers and Buzz Baum discussing the evolution of complex cells with Misha Glenny.

www.bbc.co.uk/programmes/m...

Slow and steady!

After 15 years of continuous cultivation, we finally isolated the first psychrotolerant ammonia-oxidizing archaeon (AOA) from an arctic environment, Ca. Nitrosocosmicus articus!

Our new article in Frontiers in Microbiology: doi.org/10.3389/fmic...

Asgard archaea: have we found our microbial ancestors? - The EMBO Journal The discovery of Asgard archaea about a decade ago has greatly reshaped our understanding of archaeal evolution and the origin of eukaryotes. Asgards are currently thought to be the closest prokaryoti...

Our Review Article is online!
We are happy to share our summary about molecular and cellular biological discoveries in archaea that have long foreshadowed a close relationship to eukaryotes, which is now so well manifested in the Asgard archaea.

link.springer.com/article/10.1...

bsky.app/profile/amer...

Congratulations Silvia Bulgheresi, PROSE Award Category Winner for her book Brave Genomes:
shop.elsevier.com/books/brave-...

Thank you @carlzimmer.com for sharing the excitement for our favorite organisms and introducing them to the broader audience!

www.nytimes.com/2026/02/18/s...

Viruses, heat, drought: How microbes and plants survive Viruses, heat, drought: Microbes and plants endure a lot and have developed amazing survival strategies. Biologists such as Isabelle Zink and Wolfram Weckwerth from the University of Vienna aim to bet...

Interview with Isabelle Zink and Wolfram Weckwerth on plants and microbes under stress:

rudolphina.univie.ac.at/en/viruses-h...

Thank you Susanne Erdmann and @schurlab.bsky.social for this collaboration and our excellent cultivation crew for the support!

We are happy to share our newest preprint on a novel strain of Ca. Lokiarchaeum ossiferum, that contains an active provirus, capable of excision and independent replication! We propose a novel virus family: Fylgjaviridae.

www.biorxiv.org/content/10.6...

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There are a couple of possibilities, but one is trying to move! We were able to get some more info from the lead author and just reposted some of his comments on new videos to help guide us more. They might offer some insights as well!

Thank you! We are very proud of our group members' hard work. The 𝘝𝘢𝘮𝘱𝘺𝘳𝘦𝘭𝘭𝘢 video is also amazing! Very fun to see.

This work was led by PostDoc Philipp Radler @radler92.bsky.social with the help of Tobias Viehböck. Strain HC1 and actin inhibitors were provided by Hiro Imachi @hiro-imachi.bsky.social and Klemens Rottner/Theresia Stradal respectively. We thank all collaborators for excellent input and discussions!

Thus, we suggest that these dynamics are a common feature of Promethearchaeota. The motility seems dependent on internal, actin filaments, which suggests than actin-based motility might not be an invention by eukaryotes but has emerged earlier during evolution.

Video 5 (HC1)

We were very happy to collaborate with the team of Hiro Imachi, who provided their recently cultivated Hodarchaeum Ca. M. peptidophilum, another member of the Promethearchaeota. We found these cells to be incredibly dynamic and rearranging their cell morphology, like the Lokis.

Video 4 (Actin Inhibition)

We were able to stop these dynamics by inhibiting the internal Lokiactin (an ancient homologue of human actin) cytoskeleton. Rather than controlled protrusion growth and movement, the cells sway randomly, similar to the Inflatable tube man found next to car dealerships.

Video 3 (Moving Cells)

When we looked closer, we found some that, after adhering to the glass, used their protrusions to migrate along the glass! This type of crawling motility is untypical of prokaryotes, as it didn’t seem to be dependent on Pili proteins, but rather these dynamic protrusions.

Video 2 (Shapechangers)

Not only are the arms dynamic, but also the cell shape is extremely plastic. The cells can rearrange from a spherical shape to form a stick like morphology in a matter of minutes! Such plasticity is unprecedented in the world of prokaryotes.

Video 1 (Dynamic protrusions)

These cells (we call them lovingly Lokis) have a very characteristic shape: A central cell body with long protrusions. We find these protrusions to be unexpectedly dynamic; they grow and retract constantly.

In our recent preprint, we managed to establish anaerobic live imaging of Ca. Lokiarchaeum ossiferum, a member of Promethearchaeota (formerly Asgard archaea). Below are 4 examples (plus one of the newly cultivated HC1) of these fascinating microorganisms and what we are observing:

This phylum has gathered lots of attention in the last decade, as it constitutes the closest prokaryotic lineage of eukaryotes and contains a multitude of “eukaryotic” signature proteins!

There are currently only 5 cultivated Asgards and we know most about them from genomic data and some exquisite cryo-EM images. We were, however, interested in observing cell behavior with live cell microscopy!

Dynamic protrusions mediate unique crawling motility in Asgard Archaea (Promethearchaeota) Crawling motility is a hallmark of eukaryotic cells and requires a dynamic actin cytoskeleton, regulated adhesion, and spatially organized signalling pathways1–3. Asgard archaea (phylum Promethearchae...

1. As we recently joined BlueSky, we want to repost this story for all newcomers!

We sat down with @radler92.bsky.social to get more insight into the unique videos from his recent preprint on Promethearchaeota (formerly Asgard archaea).

doi.org/10.1101/2025...

(Videos and info below)

This work was led by PostDoc Philipp Radler @radler92.bsky.social with the help of Tobias Viehböck. Strain HC1 and actin inhibitors were provided by Hiro Imachi @hiro-imachi.bsky.social and Klemens Rottner/Theresia Stradal respectively. We thank all collaborators for excellent input and discussions!

Thus, we suggest that these dynamics are a common feature of Promethearchaeota. The motility seems dependent on internal, actin filaments, which suggests than actin-based motility might not be an invention by eukaryotes but has emerged earlier during evolution.

Video 4 (Actin Inhibition)

We were able to stop these dynamics by inhibiting the internal Lokiactin (an ancient homologue of human actin) cytoskeleton. Rather than controlled protrusion growth and movement, the cells sway randomly similar to the inflatable tube man found next to car dealerships.

Video 3 (Moving Cells)

When we looked closer, we found some that, after adhering to the glass, used their protrusions to migrate along the glass! This type of crawling motility is untypical of prokaryotes, as it didn’t seem to be dependent on Pili proteins, but rather these dynamic protrusions.

Video 2 (Shapechangers)

Not only are the arms dynamic, but also the cell shape is extremely plastic. The cells can rearrange from a spherical shape to form a stick like morphology in a matter of minutes! Such plasticity is unprecedented in the world of prokaryotes.

Video 1 (Dynamic protrusions)

These cells (we call them lovingly Lokis) have a very characteristic shape: A central cell body with long protrusions. We find these protrusions to be unexpectedly dynamic; they grow and retract constantly.