Placing barthelonids on the tree of life

September 23, 2020

Tsukuba, Japan - New species of microbial life are continually being identified, but localizing them on a phylogenetic tree is a challenge. Now, researchers at the University of Tsukuba have pinpointed barthelonids, a genus of free-living heterotrophic biflagellates typified by Barthelona vulgaris, and clarified their ancestry as well as evolution of their ATP-generation mechanisms.

A phylogenetic tree portrays species by lineage. The trunk represents a common ancestor and the branches all its evolutionary descendants; together, a monophyletic group or clade. The eukaryotic Tree of Life represents the phylogeny of all organisms with nucleated cells, ranging from unicellular protists to blue whales. Where would the barthelonids fit?

The researchers established five strains of Barthelona species from different parts of the world. Analysis of the transcriptome of one strain (PAP020), its RNA "signature," localized it on the phylogenetic tree to the base of the Fornicata clade. This indicated that the last common ancestor of the barthelonids evolutionarily diverged very early in the evolution of Metamonada.

Senior author Professor Yuji Inagaki explains: "We analyzed small subunit ribosomal DNA as well as phylogenomic data to confirm the commonality of all Barthelona strains. In order to deduce their phylogenetic position, we matched transcriptome data from PAP020 against a eukaryote-wide dataset containing 148 genes."

The transcriptome data of PAP020 also indicated the evolutionarily adapted metabolic pathways of ATP generation. The research team suspected that barthelonids, being anaerobic, possessed mitochondrion-related organelles (MROs) instead of full-fledged mitochondria, a suspicion upheld by electron microscopy. Comparison with MROs in fornicates predicted that PAP020 could not generate ATP in the MRO, as no mitochondrial/MRO enzymes involved in substrate-level phosphorylation were detected. However, PAP020 possesses a cytosolic ATP synthase, acetyl-CoA synthetase (ACS), suggesting that PAP020 generated ATP in the cytosol.

"We have furthered current hypotheses around the evolutionary history of ATP-generating mechanisms in the Fornicata clade in light of data from Barthelona strain PAP020," says Professor Inagaki. "Interestingly, the sequence ACS2 was formerly believed to be acquired at the base of the Fornicata clade, but we propose that this event occurred earlier with the common ancestor of fornicates and barthelonids. Indeed, it may have occurred further back with the last common metamonad ancestor. Loss of substrate-level phosphorylation from the MRO in the clade containing barthelonids with other fornicates could well be two discrete events."

University of Tsukuba

Related Evolution Articles from Brightsurf:

Seeing evolution happening before your eyes
Researchers from the European Molecular Biology Laboratory in Heidelberg established an automated pipeline to create mutations in genomic enhancers that let them watch evolution unfold before their eyes.

A timeline on the evolution of reptiles
A statistical analysis of that vast database is helping scientists better understand the evolution of these cold-blooded vertebrates by contradicting a widely held theory that major transitions in evolution always happened in big, quick (geologically speaking) bursts, triggered by major environmental shifts.

Looking at evolution's genealogy from home
Evolution leaves its traces in particular in genomes. A team headed by Dr.

How boundaries become bridges in evolution
The mechanisms that make organisms locally fit and those responsible for change are distinct and occur sequentially in evolution.

Genome evolution goes digital
Dr. Alan Herbert from InsideOutBio describes ground-breaking research in a paper published online by Royal Society Open Science.

Paleontology: Experiments in evolution
A new find from Patagonia sheds light on the evolution of large predatory dinosaurs.

A window into evolution
The C4 cycle supercharges photosynthesis and evolved independently more than 62 times.

Is evolution predictable?
An international team of scientists working with Heliconius butterflies at the Smithsonian Tropical Research Institute (STRI) in Panama was faced with a mystery: how do pairs of unrelated butterflies from Peru to Costa Rica evolve nearly the same wing-color patterns over and over again?

Predicting evolution
A new method of 're-barcoding' DNA allows scientists to track rapid evolution in yeast.

Insect evolution: Insect evolution
Scientists at Ludwig-Maximilians-Universitaet (LMU) in Munich have shown that the incidence of midge and fly larvae in amber is far higher than previously thought.

Read More: Evolution News and Evolution Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to