Tag

Eukaryogenesis

All articles tagged with #eukaryogenesis

science8 days ago•63 min saved

Asgard archaea exhibit eukaryotic-like crawling via dynamic actin protrusions

Live-cell microscopy reveals that Asgard archaea, the closest prokaryotic relatives of eukaryotes, possess a dynamic actin-based cytoskeleton that enables crawling motility. These organisms rapidly extend and retract protrusions at speeds of 1.5 to 4.8 µm/min, a process arrested by actin inhibitors. This finding suggests that the complex cellular machinery required for eukaryotic movement evolved in archaeal ancestors before the emergence of mitochondria.

via Nature|

#asgard-archaea #cell-motility #eukaryogenesis

science23 days ago•12 min saved

Cultured Asgard microbes illuminate the origins of complex life

Scientists are finally culturing Asgard archaea, revealing eukaryotic-signature proteins and dynamic protrusions. These features, seen in multiple cultured species, bolster theories that archaea contributed key components to eukaryotic cells and suggest how endosymbiotic events and cytoskeletal innovations may have driven the rise of complex life, including the evolution of mitochondria.

via Nature|

#asgard-archaea #cytoskeleton #endosymbiosis

science3 months ago•12 min saved

Ancient archaeal toolkit predates Earth's oxygen rise

A Nature study proposes that the archaeal host lineage behind eukaryotes was already assembling complex cellular machinery in largely anoxic oceans about 2.9 billion years ago, well before substantial atmospheric oxygen. This suggests parts of eukaryotic cellular complexity predate oxygen, and that later oxygen helped expansion rather than origin. It does not prove early multicellular life; instead it highlights a CALM model and relies on molecular dating and genome comparisons, with further data needed to confirm the timeline.

via Space Daily|

#anoxic-oceans #archaea #asgard-archaea

science4 months ago•64 min saved

Diverse bacterial donors and giant viruses helped forge the first eukaryotes

A large-scale phylogenomic study reconstructs the LECA proteome and finds that, beyond the mitochondrial alphaproteobacterial endosymbiont and Asgard archaea, substantial gene acquisitions came from diverse bacteria (notably Planctomycetota and Myxococcota) and from Nucleocytoviricota giant viruses. Timing analyses reveal multiple acquisition waves, including virus-mediated transfers, suggesting that early eukaryotes arose within complex microbial ecosystems via progressive, multi-partner gene exchange, rather than a single endosymbiotic event. The LECA appears to be a chimeric organism with core metabolism, endomembrane systems, and capabilities like phagocytosis, shaped by both innovations and horizontal transfers.

via Nature|

#eukaryogenesis #horizontalgenetransfer #leca

science6 months ago•6 min saved

Shark Bay Microbes Illuminate the Birth of Complex Life

Scientists studying Shark Bay’s stromatolites report that an Asgard archaeon named Nerearchaeum marumarumayae and a sulfate-reducing bacterium may have cooperated early in life’s history. DNA sequencing, AI protein modeling, and high-resolution electron cryotomography showing nanotube connections suggest a possible precursor to the first eukaryotic cells, offering a living glimpse into how complex life may have originated. The work also honors Indigenous Malgana language in naming the microbe and highlights the cultural and environmental significance of Gathaagudu (Shark Bay).

via ScienceAlert|

#asgard-archaea #eukaryogenesis #microbial-mats

science7 months ago•7 min saved

Ancient Asgard Microbes May Reveal How Oxygen Enabled Complex Life

Genome analyses reveal oxygen-tolerant Asgard archaea in shallow coastal sediments, suggesting some ancient ancestors used oxygen before merging with bacteria to form eukaryotes, strengthening the link between rising Earth oxygen and the origin of complex life.

via CNN|

#asgard-archaea #eukaryogenesis #great-oxidation-event

science7 months ago•1 min saved

Transitional Microbes Point the Way to Complex Cell Origins

A wave of new studies identifies rare transitional microbes, such as Lokiarchaeum ossiferum, that bridge simple cells and complex eukaryotic cells, offering clues to how cells with nuclei and mitochondria evolved about two billion years ago.

via The New York Times|

#cell-biology #endosymbiosis #eukaryogenesis

science8 months ago•62 min saved

Asgard archaea dominate early eukaryotic evolution, mitochondria arrive later

A comprehensive phylogenomic analysis shows Asgard archaea contributed the majority of core eukaryotic genes traced to LECA, with Alphaproteobacteria providing mainly mitochondrial-related components and energy metabolism; other bacteria contributed sporadically without clear patterns. This supports a model where key eukaryotic features—cytoskeleton and endomembrane system—evolved in the Asgard lineage before LECA, with mitochondria acquired later and additional bacterial genes entering gradually via HGT. The study uses soft-core pangenomes and constrained trees to minimize late HGT and test origins, though conclusions depend on the current sampling of Asgard and bacterial genomes.

via Nature|

#asgard-archaea #eukaryogenesis #horizontal-gene-transfer

biology10 months ago•51 min saved

Revealing the Ancient Origins and Evolution of Complex Life on Earth

The article uses molecular clock analyses of gene duplications to establish a timeline for eukaryotic cell evolution, suggesting that key features like the nucleus, cytoskeleton, and endomembrane system developed before mitochondrial endosymbiosis, with the divergence of eukaryotic lineages occurring around 1.8 billion years ago.

via Nature|

#biology #eukaryogenesis #eukaryotes

science3 years ago•5 min saved

Asgard Cells Reveal Early Signs of Complexity in Life.

The study of Asgard archaea, a group of microbes that may be the closest living relatives of eukaryotes, is shedding light on the origins of complex life. Researchers have cultivated two species of Loki, a type of Asgard archaea, and found that they have tentacle-like filaments made of a protein called Lokiactin, which closely resembles the actin used by eukaryotic cells to build supportive cytoskeletons. This adds plausibility to the inside-out model of eukaryogenesis, which proposes that the first eukaryotes were born after a simple ancestral cell extended protrusions past its cell walls and closed around a symbiotic bacterium, turning it into a proto-mitochondrion.

via Quanta Magazine|

#asgard-archaea #eukaryogenesis #loki-organism