Bacteria Breed Multicellularity?

A single-celled relative of animals forms colonies when exposed to a bacterial product, hinting at the possible origins of multicellularity.

By | August 15, 2012

Choanoflagellate individuals (left) and colonies (right). ADAPTED FROM ALEGADO ET AL., 2012

Choanoflagellates, single-celled flagellates, have been thought of as a model for multicellularity since the 1800s because they live either as individuals or in colonies shaped like rosettes. The way colonies form is also intriguing: when daughter cells are spawned, they stick around instead of breaking up, in what looks at first glance like the dividing cells of an embryo. Now, in a paper to be published in the first issue of the upcoming open-access journal eLife, a driving factor of rosette formation has been uncovered. A sulfonolipid, produced by a bacteria that choanoflagellates eat, induces colony development, raising the possibility that bacteria were involved in the evolution of multicellular life.

"The origin of eukaryotic cells occurred in a really dense mass of bacteria," said zoologist Michael Hadfield at the University of Hawaii, who was not involved in the study. There's "just no way" that those first organisms weren't involved with bacteria in many ways beyond just feeding on them, he said. "What this new paper shows us is that there's this really fundamental connection going on here between [bacteria] and things that operate as single cells ,then start operating as colonies."

While recent genetic studies of choanoflagellates have reinforced their position as good models of multicellularity, it had proven hard to make them cooperate in the lab. In Nicole King's lab at Berkeley, however, by treating them with antibiotics—a ruthless measure to stop the choanoflagellates being overrun by bacteria—researchers found the rosettes would no longer form. Suspecting the bacteria thus had a role in rosette formation, the team tested over 60 bacterial strains that were associated with the original choanoflagellate sample, and found just one that was associated with the choanoflagellates sticking together upon dividing.

"This wasn't an autonomous decision by the choanoflagellates, but it was something prompted by their environment," said John Clardy, a molecular biologist at Harvard who helped identify the compound responsible.

The bacterium responsible was a newly discovered species (Algoriphagus machipongonensis) of the phylum Bacteroidetes, other members of which influence algal development and even the development of the immune system in animals. By feeding groups of choanoflagellates different bacterial species from the original sample, the team found that when fed solely on A. machipongonensis, the choanoflagellates produced high numbers of rosettes. This phenomenon was not observed with any of the other bacteria. The chemical mechanisms of bacterial interactions are poorly understood, however, and it took the team a while to isolate the compound responsible. It turned out to be a rare lipid, a sulpholipid they termed Rosette-Inducing Factor 1 (RIF-1). The compound appears to be remarkably potent, with just nanomoles of the stuff necessary to induce rosette formation. Intriguingly, rosettes are more efficient than individuals at capturing A. machipongonensis and consuming them, and why the bacteria would produce a compound that quickens their demise is a mystery the team are pursuing.

While choanoflagellates are not our ancestors, Hadfield is excited by the implications of the finding in a close relative to all animals. "It suggests that [to go] from single-celled animals that had to catch and eat their food to a multicellular state, bacteria were involved," he said.

Whether it is the origin of multicellular life, however, is an open question, according to Clardy. "You can talk to people who will say 'No, this is only one way,' or 'This is a red herring,’" he said. "But what I think is interesting is that this is a fabulous example of how bacteria profoundly influence the development of eukaryotes."

"It's a remarkable discovery," said Randy Schekman, a cell biologist at the University of California and the editor-in-chief of eLife. "Who would have guessed a molecule like that could be involved in colonization?" Schekman has been aware of the work in King's lab for some time, and when he heard about the results they'd achieved, he set about encouraging them to submit a paper to his new open-access venture. Convincing all of the paper's authors that they would get the appropriate exposure wasn't easy for a new journal, Schekman said, but in the end they wanted to take part in a new model of open-access publishing. (See this month's feature on the future of science publishing for more discussion of open-access publishers.) The full article will be published in eLife's first issue, to be released in a couple of months, but a pre-print is currently available on the King lab website.

R. Alegado et al., "Bacterial regulation of colony development in the closest living relatives of animals," eLife, citation to be confirmed, 2012.


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Avatar of: James Kohl

James Kohl

Posts: 53

August 17, 2012

Excerpted from the article: “Who would have guessed a molecule like that could be involved in colonization?â€쳌

In Kohl (2012) I wrote that reproduction began with an active nutrient uptake mechanism in heterospecifics and that the mechanism evolved to become symbiogenesis in the conspecifics of asexual organisms, citing Margulis (1998). My speculation was based on the fact that nutrient chemicals are required for individual survival and the fact that metabolism of the nutrient chemical to pheromones controls reproduction via the molecular biology of intracellular signaling and stochastic gene expression, which is common to all species. The common molecular biology makes it clear that integrated chemical ecology (the epigenetic effects of nutrient chemicals and pheromones) is required for adaptive evolution (e.g., via ecological, social, neurogenic, and socio-cognitive niche construction.)

The authors of this article make it clear to me that chemical signals akin to species-specific pheromones are responsible for the ligand-receptor binding that may enable the progression to colony formation as a more effective means of nutrient acquisition. This must occur at the same time that quorum sensing ensures the supply of nutrients is not exhausted. Thus, the symbiotic relationship is maintained, which at least partially explains why one organism might produce a species-specific 'pheromone' that promoted it species' survival via a signal of what's for dinner to a heterospecific diner -- at least in theory.

Avatar of: Ashwini Kumar

Ashwini Kumar

Posts: 1

August 22, 2012

The RIF-1 induced only colony formation or aggregates, as i suppose. If it is multicellular form, it should have a division of labour, as shown by multicellular organisms. Is this property shown? Aggregates of cells are also found in cell cultures, but it is not said to be multicellular forms.....can anyone please explain?

Avatar of: wendalkane23


Posts: 1

August 28, 2012

While these colonies are not multicellular organisms, the step from single to colonial is a huge leap in the direction of becoming multicelled. You wouldn't have cells come together already dividing the labor, it just wouldn't make sense.

Avatar of: Dov Henis

Dov Henis

Posts: 14

October 12, 2012

Uni- To Multi-Cellular Evolution

Tags: brain origin, gravitation, gravitons, lifeevolution, nerved organisms, RNAlifehood, spirituality, universeevolution

From: Dov Henis

Sent: Thursday, August 16, 2012 6:45 PM

To: ''

Subject: ReYr article, I posted tens of data-based articles describing the marked subjects below, during the past 15 years...also in The Scientist…

The Wheel Is Invented! Read All About It!

Update AAAS religious trade union concepts:

Natural Selection Is Ubiquitous

Higgs Particle? Dark Energy/Matter? Epigenetics? These Are All YOK!

Update Concepts-Comprehension…

Evolution Is The Quantum Mechanics Of Natural Selection.

The quantum mechanics of every process is its evolution.

Quantum mechanics are mechanisms, possible or probable or actual mechanisms of natural selection.


Universe-Energy-Mass-Life Compilation

A. The Universe

From the Big-Bang it is a rationally commonsensical conjecture that the gravitons, the smallest base primal particles of the universe, must be both mass and energy, i.e. inert mass yet in motion even at the briefest fraction of a second of the pre Big Bang singularity. This is rationally commonsensical since otherwise the Big would not have Banged, the superposition of mass and energy would not have been resolved.

The universe originates, derives and evolves from this energy-mass dualism which is possible and probable due to the small size of the gravitons.

Since gravitation Is the propensity of energy reconversion to mass and energy is mass in motion, gravity is the force exerted between mass formats.

All the matter of the universe is a progeny of the gravitons evolutions, of the natural selection of mass, of some of the mass formats attaining temporary augmented energy constraint in their successive generations, with energy drained from other mass formats, to temporarily postpone, survive, the reversion of their own constitutional mass to the pool of cosmic energy fueling the galactic clusters expansion set in motion by the Big Bang.

B. Earth Life

Earth Life is just another mass format. A self-replicating mass format. Self-replication is its mode of evolution, natural selection. Its smallest base primal units are the RNAs nucleotide genes.

The genesis of RNAs genes, life’s primal organisms, is rationally commonsensical thus highly probable, the “naturally-selected” RNA nucleotides.

Life began/evolved on Earth with the natural selection of inanimate RNA, then of some RNA nucleotides, then arriving at the ultimate mode of natural selection, self-replication.

C. Know Thyself. Life Is Simpler Than We Are Told, Including Origin-Nature Of Brain-Consciousness-“Spirituality”*

The origin-reason and the purpose-fate of life are mechanistic, ethically and practically valueless. Life is the cheapest commodity on Earth.

As Life is just another mass format, due to the oneness of the universe it is commonsensical that natural selection is ubiquitous for ALL mass formats and that life, self-replication, is its extension. And it is commonsensical, too, that evolutions, broken symmetry scenarios, are ubiquitous in all processes in all disciplines and that these evolutions are the “quantum mechanics” of the processes.

Human life is just one of many nature’s routes for the natural survival of RNAs, the base primal Earth organisms.

Life’s evolution, self-replication:

Genes (organisms) to genomes (organisms) to mono-cellular to multicellular organisms:

Individual mono-cells to cooperative mono-cells communities, “cultures”.

Mono-cells cultures evolve their communication, neural systems, then further evolving nerved multicellular organisms.

Human life is just one of many nature’s routes for the natural survival of RNAs, the base Earth organism.

It is up to humans themselves to elect the purpose and format of their life as individuals and as group-members.

Dov Henis (comments from 22nd century)

***????? ?????? ?? "?????????", ???? ??????????,

?????????? ?????? ?????????, ?????? ??????? ????

An Embarrassingly Obvious Theory Of Everything

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