{"id":773163,"date":"2026-09-17T02:50:39","date_gmt":"2026-09-17T02:50:39","guid":{"rendered":"https:\/\/www.newsbeep.com\/uk\/773163\/"},"modified":"2026-09-17T02:50:39","modified_gmt":"2026-09-17T02:50:39","slug":"these-bizarre-much-coveted-microbes-are-revealing-the-origins-of-complex-life","status":"publish","type":"post","link":"https:\/\/www.newsbeep.com\/uk\/773163\/","title":{"rendered":"These bizarre, much-coveted microbes are revealing the origins of complex life"},"content":{"rendered":"\n

Over two days in June, Emily Aguilar-Pine drove 2,500 kilometres from Bozeman, Montana, to Austin, Texas, with one of microbiology\u2019s most coveted organisms in the back of her mother\u2019s SUV. Inside some protective packaging, labelled \u2018hopes and dreams\u2019, was a small bottle containing about 30 millilitres of what looked like clear liquid, but that in fact held a type of Asgard archaeon<\/a>, single-celled organisms named after the realm of the Norse gods. At night, \u2018Skadi\u2019, short for what is provisionally called Skadiarchaeum cthulhuensis, hung out in the hotel room with Aguilar-Pine. \u201cIt was with me at all times,\u201d she says.<\/p>\n

\"\"<\/p>\n

The trickster microbes that are shaking up the tree of life<\/p>\n

<\/a><\/p>\n

Researchers discovered Asgard archaea in 2015 from DNA in sediments plucked from the bottom of the North Atlantic1<\/a>. The find changed scientists\u2019 views on the origin of eukaryotes<\/a> \u2014 the complex life forms that include everything from protists to plants, animals and fungi. Researchers knew that eukaryotes had emerged from prokaryotes, single-celled organisms that include bacteria and archaea, and the evidence strongly suggested a close relationship with archaea<\/a>. But analysis of the Asgard genomes has since pointed to these archaea specifically as the ancestral line of all eukaryotes. Most researchers who study the issue now consider there to be only two domains of life on the planet; eukaryotes are but a branch of archaea and everything else is bacteria.<\/p>\n

What\u2019s known about Asgard archaea has come mostly from their DNA<\/a>. Scientists have been sequencing all the genetic material that they can find in environmental samples and piecing together the microbial genomes within. Although hundreds of Asgard species have been identified in this way2<\/a> from a variety of ecosystems around the world, the microorganisms are present in such low abundance that it is difficult to isolate them for study. But researchers who have persisted are now establishing relatively stable cultures<\/a> \u2014 with enough Asgard cells that they can be seen under a microscope.<\/p>\n

\"A<\/p>\n

The Asgard Nerearchaeum marumarumayae.Credit: Dr Matthew D Johnson, Dr Bindusmita Paul and Associate Professor Debnath Ghosal<\/p>\n

The first cultures were reported3<\/a>,4<\/a> in 2020 and 2022, with four more announced5<\/a>\u20137<\/a> since the start of 2025. There are at least a few more that have not yet appeared in the literature, including Skadi, which Aguilar-Pine learnt to care for from a PhD student, Stavros Trimmer, at Montana State University in Bozeman before taking samples back with her to the University of Texas at Austin. And researchers are working on more Asgard archaea, encouraging the fickle, slow-growing cells to proliferate, often over the course of several years. The pay-off is worth it, they say.<\/p>\n

\u201cAsgard are by far the coolest thing to happen to microbiology in the last 30 to 40 years,\u201d says microbiologist Paul Carini at the University of Arizona in Tucson, whose laboratory is working with an unpublished culture that originated in an estuarine environment in Oregon. Scientists are now studying the surprising shapes, features and behaviours of these cells \u2014 and are turning up clues about what made the transition to complex life possible<\/a>.<\/p>\n

Not so simple<\/p>\n

The defining features of eukaryotic cells \u2014 a membrane-bound nucleus and specialized organelles \u2014 might not leap out as extraordinary. But they opened vast new possibilities for how living things could evolve. By keeping their DNA separate from the rest of the cell, eukaryotic cells can protect it and better control how genes are expressed. Internal compartments allow cells to localize tasks and perform many jobs at once. And mitochondria, which power the cells, allow eukaryotes to produce large amounts of energy through aerobic respiration. Cells were able to get much bigger; organisms could become multicellular; and they could reproduce sexually.<\/p>\n

\"\"<\/p>\n

The mysterious microbes that gave rise to complex life<\/p>\n

<\/a><\/p>\n

It\u2019s generally thought that the split between prokaryotes and eukaryotes happened around two billion years ago, when an ancient host archaeon \u2014 now recognized as a member of the Asgards \u2014 engulfed a free-living bacterium<\/a>. That bacterium, which was in a mutually beneficial \u2018endosymbiotic\u2019 partnership with the archaeon, eventually evolved into the present-day mitochondrion. Earth\u2019s environment was changing drastically at the time, with oxygen building up in the oceans and atmosphere. Life that could take advantage of it gained an edge.<\/p>\n

But how the microbes involved in this monumental partnership found each other, which one contributed what to the relationship, and what physical processes led to the engulfment are big unknowns.<\/p>\n

One idea is that, before the endosymbiotic event, the supposedly simple host cells must have had some of the capacities required for complex life. The discovery of Asgards has lent support to this idea1<\/a>,8<\/a>. Asgard genomes encode a wide variety of proteins<\/a> once thought to be exclusive to eukaryotes. These \u2018eukaryotic signature proteins\u2019 have roles in the formation of a dynamic cytoskeleton, which gives cells structure and enables movement, as well as in the shuttling of proteins and lipids between cellular compartments and the building and remodelling of membranes.<\/p>\n

Wild cells<\/p>\n

By culturing the microbes, scientists can study what these proteins do in Asgard cells, including how they relate to the physical features that are now being observed (see \u2018Oddball Asgards\u2019).<\/p>\n

\"Illustration<\/p>\n

The most talked about of these features so far are the tiny protrusions that look like tentacles, or even antlers, jutting out from Asgards\u2019 typically spherical bodies.<\/p>\n

Microbiologists Hiroyuki Imachi and Masaru Nobu first saw the protrusions in an Asgard that they spent a dozen years growing in their lab at the Japan Agency for Marine-Earth Science and Technology in Yokosuka. When the project started, they didn\u2019t know that they had an Asgard in their bioreactor; Asgard as a group had not yet been identified.<\/p>\n

But in 2020, they were able to report the first successful culture of an Asgard archaeon, Promethearchaeum syntrophicum3<\/a>. They described a \u201cpure co-culture\u201d that also contained a methane-producing partner \u2014 another archaeon \u2014 that they couldn\u2019t grow P. syntrophicum without.<\/p>\n

The paper highlighted the protrusions. \u201cMy initial reaction was funny,\u201d Imachi says. \u201cI wondered whether some material had contaminated the sample or whether it was an artefact of the observation process.\u201d But the protrusions seem to be genuine and have been observed many times over.<\/p>\n

\"\"<\/p>\n

A \u2018lost world\u2019 of early microbes thrived one billion years ago<\/p>\n

<\/a><\/p>\n

The next published culture, from microbiologist Christa Schleper\u2019s lab at the University of Vienna, took six years to grow from samples collected from shallow sediments off the coast of Slovenia. It included five microbial species, with an Asgard among the dominant ones. With advanced imaging techniques, the researchers, including microbiologist Martin Pilhofer at the Swiss Federal Institute of Technology (ETH) in Zurich, got a good look inside the Asgard cells. \u201cI was completely shocked,\u201d says Pilhofer. The cells had protrusions, and they lacked both the rigid protein shell often seen in archaea and bacteria and the double membrane or cell wall of eukaryotic cells. \u201cThese cells looked like nothing I had ever seen,\u201d he says.<\/p>\n

Their 2022 paper reported an Asgard provisionally called Lokiarchaeum ossiferum. (The names of cultured Asgards are often preceded by Candidatus in the literature to reflect that they are still \u2018candidate\u2019 names.) It has a cytoskeleton with filaments made up of actin-like proteins similar to those found in eukaryotes4<\/a>. The researchers later reported the presence of microtubules9<\/a>, another feature of eukaryote cytoskeletons. Both P. syntrophicum and L. ossiferum belong to the Loki group of Asgards, which takes its name from Loki\u2019s Castle, the field of Atlantic hydrothermal vents where Asgards were first discovered.<\/p>\n

The protrusions have become an iconic feature of Asgards, observed in almost every culture. What they do is not yet clear, however. \u201cThe cell invests a substantial amount of its resources in building and maintaining these structures, so they must serve some important biological functions,\u201d Imachi says.<\/p>\n

Some ideas are emerging. In a preprint posted in late 2025, Schleper and her colleagues used live microscopy to capture, for the first time, Asgard cells in motion. L. ossiferum and another cultured species from Imachi and Nobu\u2019s team, Margulisarchaeum peptidophilum, seem to crawl by reshaping the cytoskeleton in their protrusions10<\/a>. Inhibiting the actin-like proteins stopped cell movement.<\/p>\n

\"Lokiarchaeum<\/p>\n

The Asgard archaeon Lokiarchaeum ossiferum uses protrusions to move around on a surface.Credit: Philipp Radler<\/p>\n

In a paper on M. peptidophilum and another Asgard, Flexarchaeum multiprotrusionis, both of which took three years to cultivate, Imachi and Nobu report observing protrusions attaching to methane-producing partners through what Imachi describes as spikes on their surface, suggesting the protrusions might help to capture and retain partners7<\/a>. This result and others raise the tantalizing possibility that Asgard protrusions could have been instrumental in the origin of eukaryotes.<\/p>\n

\u201cIt is of course very exciting at the moment,\u201d says Schleper. \u201cWhenever I look at our cells, and we do more experiments, we get so surprised. We always find something that we did not even think of.\u201d<\/p>\n

Cell biologist Buzz Baum at the MRC Laboratory of Molecular Biology in Cambridge, UK, says the protrusions fit with a model of eukaryogenesis that he and his cousin, evolutionary biologist David Baum at University of Wisconsin\u2013Madison, proposed in 2014. Dubbed the inside-out model11<\/a>, it posits that an ancient archaeon would have used protrusions to share resources with other cells. Instead of the cell folding its membrane in to engulf a partner microbe, the protrusions would eventually surround the mitochondrial precursor and merge to trap it.<\/p>\n

\"\"<\/p>\n

Scientists glimpse oddball microbe that could help explain rise of complex life<\/p>\n

<\/a><\/p>\n

Another cultured Asgard, found in microbial mats in Shark Bay in Western Australia, has its own surprises. Microbial ecologist Brendan Burns at UNSW in Sydney, Australia, and his colleagues see chains of vesicles dangling on the outside of cell bodies in Nerearchaeum marumarumayae, which took five years to grow to high abundance5<\/a>. They also see a long thin tube reaching out from a partner bacterium and touching the Asgard. \u201cI couldn\u2019t believe that I was seeing a physical interaction,\u201d recalls structural biologist Debnath Ghosal at the University of Melbourne, Australia, whose team did the imaging work. \u201cI\u2019m getting goosebumps now thinking about it.\u201d What, if anything, is being exchanged between the microbes is unknown.<\/p>\n","protected":false},"excerpt":{"rendered":"Over two days in June, Emily Aguilar-Pine drove 2,500 kilometres from Bozeman, Montana, to Austin, Texas, with one…\n","protected":false},"author":2,"featured_media":773164,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[10],"tags":[15378,4390,59,102,4230,33192,4231,90,56,54,55],"class_list":["post-773163","post","type-post","status-publish","format-standard","has-post-thumbnail","category-health","tag-cell-biology","tag-evolution","tag-gb","tag-health","tag-humanities-and-social-sciences","tag-microbiology","tag-multidisciplinary","tag-science","tag-uk","tag-united-kingdom","tag-unitedkingdom"],"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/posts\/773163","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/comments?post=773163"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/posts\/773163\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/media\/773164"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/media?parent=773163"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/categories?post=773163"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/tags?post=773163"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}