Latest news with #Sukunaarchaeummirabile
USA Today
06-07-2025
- Science
- USA Today
What is life? A little microbe raises big questions.
It's tiny and needy, but is it alive? That's a question prompted by recent research that highlights a surprisingly complex part of biology. The organism in question is a microbe called Sukunaarchaeum mirabile, discovered by researchers in Canada and Japan who were looking at the DNA of a species of marine plankton, according to a new paper published on bioRxiv. They've found it's unusually reliant on an alive host to survive, which could further blur the lines between cellular life and viruses — which generally considered to not be alive. The National Human Genome Research Institute describes viruses as existing "near the boundary between the living and the nonliving." Viruses can't function without interacting with a living cell. On their own, they're also essentially inert – unable to move – as a 2017 study notes. Enter Sukunaarchaeum mirabile, which could complicate things further. What is it? "This organism represents a totally new branch in the archaeal tree of life," lead researcher Takuro Nakayama of the University of Tsukuba told USA TODAY. (Archaea are microorganisms that define the limits of life on Earth.) "Sukunaarchaeum is not a virus, but a highly streamlined cellular organism," Nakayama said. According to the new study, which has yet to be peer-reviewed, "the discovery of Sukunaarchaeum pushes the conventional boundaries of cellular life and highlights the vast unexplored biological novelty within microbial interactions." Named for a Japanese deity Named for a Japanese deity known for its tiny size, Sukunaarchaeum has one of the smallest genomes ever recorded: "Its genome is drastically reduced – less than half the size of the previously smallest known archaeal genome," Nakayama said. The authors in the study write that "its genome is profoundly stripped-down, lacking virtually all recognizable metabolic pathways, and primarily encoding the machinery for its replicative core: DNA replication, transcription, and translation." "This suggests an unprecedented level of metabolic dependence on a host, a condition that challenges the functional distinctions between minimal cellular life and viruses,' the study says. 'The tip of the iceberg' "Sukunaarchaeum could be just the tip of the iceberg, pointing to a hidden diversity of life forms with ultra-reduced genomes within the so-called 'microbial dark matter,'" Nakayama told USA TODAY. Indeed, the discovery of Sukunaarchaeum's bizarrely viruslike way of living 'challenges the boundaries between cellular life and viruses,' Kate Adamala, a synthetic biologist at the University of Minnesota Twin Cities who was not involved in the work, told Science magazine. 'This organism might be a fascinating living fossil – an evolutionary waypoint that managed to hang on.' The study concludes that "further exploration of symbiotic systems may reveal even more extraordinary life forms, reshaping our understanding of cellular evolution." What does 'life' mean to scientists? "I am not an expert on the philosophical definition of 'life," Nakayama said, adding that the definition is not uniform among scientists and is a subject of continuous debate. "Many scientists would agree that cellular structure, the ability to replicate, and the ability to metabolize are key features of life. Viruses typically lack these features," he said. "The discovery of Sukunaarchaeum is interesting in this context because it lacks one of those key features: metabolism. The existence of a cellular organism that seemingly lacks its own metabolism provides a new and important perspective to the ongoing discussion about the definition and minimal requirements of life." Contributing: Joel Shannon, USA TODAY
Time of India
03-07-2025
- Science
- Time of India
Meet the organism which hangs somewhere between life and death
Scientists have discovered Sukunaarchaeum mirabile, a unique archaeon residing within marine plankton, challenging traditional definitions of life. This microbe possesses a stripped-down genome, enabling protein production but lacking metabolic pathways, blurring the lines between cellular life and viruses. Its discovery prompts a reevaluation of life's boundaries and evolutionary origins. Scientists have long debated what truly counts as 'alive.' On one side of the spectrum lie conscious animals and self-replicating single-celled organisms, whereas on the other side are viruses, which are the biological entities that can only function once they hijack a host. Viruses don't grow, reproduce independently, or generate their own energy, so they're usually excluded from the tree of life. But life's boundaries aren't always clear-cut. New discoveries are challenging the binary notion of 'living' versus 'non-living.' A recently discovered organism is a surprising microbe that shares traits with both viruses and cellular life. It can construct its own ribosomes and messenger RNA, yet it lacks most metabolic pathways and relies heavily on its host. So this brings us to some unanswered questions like, what defines life? Where do we draw the line? And could this microbe represent a missing link in evolutionary biology? Researchers led by Ryo Harada at Dalhousie University uncovered an unusual archaeal organism within the marine plankton Citharistes regius. While studying the plankton's bacterial genome, they discovered a circular DNA fragment that didn't match any known species. Detailed analysis showed the scientists that it belongs to the Archaea domain and is provisionally named Sukunaarchaeum mirabile, inspired by a tiny Japanese deity. This virus can produce its own proteins! Surprisingly, its genome is just 2,38,000 base pairs, which is about half the size of the smallest previously known archaeal genome, which was 490 kbp. by Taboola by Taboola Sponsored Links Sponsored Links Promoted Links Promoted Links You May Like Искате да научите повече за новото BMW 2 Gran Coupe? BMW Научете повече Undo 'Its genome is profoundly stripped‑down, lacking virtually all recognizable metabolic pathways, and primarily encoding the machinery for its replicative core: DNA replication, transcription, and translation,' the team of researchers revealed in the study. This minimal genome means an undefined metabolic dependence on its host. Still, Sukunaarchaeum retains key machinery most viruses lack, like the genes for building ribosomes, transfer RNA, and messenger RNA. Unlike viruses, which rely fully on host machinery, this archaeon can perform fundamental cellular processes. The team says, 'Sukunaarchaeum may represent the closest cellular entity discovered to date that approaches a viral strategy of existence'. This virus belongs to an old branch of a family tree Study also reveals that the scientists found that Sukunaarchaeum mirabile belongs to a very old and unique branch of the Archaea family tree, which is so unique that it may come from a group of microbes that have never been observed before. Even though researchers have done tons of environmental DNA sequencing over the years, this strange little organism stayed hidden inside plankton DNA until now. Its tiny, simplified genome is making scientists rethink how we define life. Sukunaarchaeum blurs the line between the smallest living cells and complex viruses. It can copy its own DNA and make proteins, things that viruses usually can't do on their own, but it still relies completely on its host to survive because it can't produce its own energy. In short, this organism sits in a gray area between life as we know it and the strange, parasitic world of viruses.
