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#eukaryotes

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Benjamin Carr, Ph.D. 👨🏻‍💻🧬

Giant, #Ancient Life Form Doesn’t Fit Into Any Known Branch of Life
Scientists have debated where #Prototaxites belong in tree of life for over a century, but now a new study suggests it might represent a whole new branch.
Researchers analyzed #fossil of Prototaxites species called Prototaxites taiti and concluded that it belonged to now-extinct lineage of multicellular #terrestrial #eukaryotes (organisms, including all animals and plants, whose cells contain a nucleus).
gizmodo.com/giant-ancient-life

Gizmodo · Giant, Ancient Life Form Doesn’t Fit Into Any Known Branch of LifeScientists have debated where Prototaxites belong in the tree of life for over a century, but now a new study suggests it might represent a whole new branch.
Victoria Stuart 🇨🇦 🏳️‍⚧️

Eukaryotic cell emerged as evolutionary algorithmic phase transition
sciencedaily.com/releases/2025
press.uni-mainz.de/eukaryotic-
pnas.org/doi/10.1073/pnas.2422

* compromise: conserved process of gene growth vs. change in genetic regulation which incorporated noncoding sequences
* increase in cellular complexity occurred continuously
* in abrupt manner at critical point unlocked path toward multicellular organisms

#Eukaryotes#evolution#multicellularity
Mikko Tuomi

The origin of the eukaryotic cell corresponded to the most significant increase in #complexity in the history of #life's evolution on Earth.

The billions of years that have passed since the fusion of an #archaea and a #bacteria have resulted in a lack of evolutionary intermediates in the phylogenetic tree until the emergence of the #eukaryotes.

Now researchers present theoretical and observational evidence that a phase transition in genetic complexity was involved.

phys.org/news/2025-04-evolutio

Phys.org · An evolutionary algorithmic phase transition 2.6 billion years ago may have sparked the emergence of eukaryotic cellsBy Kathrin Voigt
Mikko Tuomi

Prototaxites represents the first giant organisms to live on the terrestrial surface, reaching sizes of 8 metres in the Early Devonian.

It was an extinct lineage of #multicellular terrestrial #eukaryotes.

Assignments to groups of multicellular algae or land plants have been repeatedly ruled out leaving two major alternatives: #Prototaxites was either a #fungus or a now entirely extinct lineage.

The latter hypothesis seems more plausible based on nrw evidence.

astrobiology.com/2025/03/ancie

Astrobiology · Ancient Prototaxites Don’t Belong To Any Living Lineage - Possibly A Distinct Branch of Multicellular Earth life - AstrobiologyPrototaxites was the first giant organism to live on the terrestrial surface, reaching sizes of 8 metres in the Early Devonian
joene 🏴🍉

I already knew about #mitochondria, their maternal inheritance and of course their evolutionary roots. That we are on cell-level actually part #bacteria. But watching this, I'm wondering if we as #humans (and almost all #eukaryotes) are not just very complicated vehicles for the survival of these bacteria. 😱

Anton Petrov: *Are We Actually Controlled by Mitochondria? Mindblowing New Discoveries*

youtube.com/watch?v=vzqXeAtDnT

Sources:

- science.org/doi/10.1126/sciadv
- nature.com/articles/s41588-023
- sciencedirect.com/science/arti
- journals.plos.org/plosbiology/

YouTubeAre We Actually Controlled by Mitochondria? Mindblowing New DiscoveriesBy Anton Petrov
#biology#genetics#evolution
formuchdeliberation

Meet the Eukaryote, the First Cell to Get Organized | Quanta Magazine…

All modern multicellular life — all life that any of us regularly see — is made of cells with a knack for compartmentalization. Recent discoveries are revealing how the first eukaryote got its start... Quanta #eukaryotes #cellbiology #biology #science #evolutionarybiology #bacteria

formuchdeliberation.wordpress.

for much deliberation · Meet the Eukaryote, the First Cell to Get Organized | Quanta Magazine…All modern multicellular life — all life that any of us regularly see — is made of cells with a knack for compartmentalization. Recent discoveries are revealing how the first eukaryote got its star…
katch wreck

"By testing a series of alternative—& commonly debated—hypotheses, we demonstrate how #multicellularity was likely acquired differently in #eukaryotes & #prokaryotes owing to selective differences on their size due to the biophysical & #metabolic regimes they inhabit: decreasing temperatures... instigated by the onset of glaciations generated selective pressures towards smaller sizes in organisms in the diffusive regime & towards larger sizes in motile heterotrophs"

royalsocietypublishing.org/doi

Frank Aylward

Happy to share the latest manuscript from our lab, in which we propose that eukaryotes evolved from a genomic chimera of Asgard archaea and giant viruses.

biorxiv.org/content/10.1101/20

This is a controversial topic, but we believe we have strong evidence to suggest a critical viral role in eukaryogenesis.

bioRxiv · Chimeric Origin of Eukaryotes from Asgard Archaea and Ancestral Giant VirusesThe details surrounding the evolution of complex cells remain some of the most enduring mysteries in biology. Recent evidence has demonstrated that Asgard archaea are the closest cellular relatives of eukaryotes, but several eukaryotic enzymes involved in key cellular processes lack phylogenetic affinity with archaea. In particular, phylogenies of eukaryotic DNA and RNA polymerases often support a 3-domain topology that is not consistent with an archaeal origin. Here we present comprehensive phylogenetic analysis of eukaryotic family B DNA polymerases and multimeric RNA polymerases and show that these core subunits of these enzymes are derived from the ancestors of modern giant viruses (phylum Nucleocytoviricota). Specifically, we show that the eukaryotic delta polymerase (Polδ), a key processive polymerase required for genome replication in all eukaryotes, clusters within an ancient viral clade, strongly supporting a viral origin. By contrast, the other eukaryotic processive polymerase (Polε), clusters within an Asgard archaeal clade. Together, these observations provide a strong and direct link between early eukaryotes, Asgard archaea, and giant viruses. Lastly, we provide a comprehensive phylogenetic analysis of eukaryotic multimeric RNA polymerases to confirm that RNA polymerase II, which is responsible for mRNA transcription in eukaryotes, is also derived from the ancestors of modern giant viruses. In total, our results support a model of eukaryogenesis in which complex cells emerged from a genomic chimera of Asgard archaea and an ancient viral lineage. ### Competing Interest Statement The authors have declared no competing interest.
#viruses#protists#eukaryotes
*
michael

11-APR-2024
Scientists discover first nitrogen-fixing organelle
Meaning: #eukaryotes CAN do
#NitrogenFixation

wow. A scientific fact I mentioned in several of my books is no longer true. Also, all biology / biochemistry textbooks need to be updated. Oh well. Exciting to see such a major change though.

eurekalert.org/news-releases/1

EurekAlert!Scientists discover first nitrogen-fixing organelle<p>In two recent papers, an international team of scientists describe the first known nitrogen-fixing organelle within a eukaryotic cell. The organelle is the fourth example in history of primary endosymbiosis — the process by which a prokaryotic cell is engulfed by a eukaryotic cell and evolves beyond symbiosis into an organelle.</p>
#science#ecology#symbiosis
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