Ants use a gene ‘bulldozer’ to control chaos and stay coordinated

For ants, scent is language. Pheromones tell workers where to forage, alert them to intruders, and even help assign jobs inside the nest. Strip that chemical conversation away, and society collapses.

“They stop performing their duties, which leads to anarchy,” said Bogdan Sieriebriennikov, first author of a new Nature study from New York University. “These ants get confused and attack each other. It starts with a lack of communication and ends in catastrophe.”

That level of precision demands tight genetic control. Ants carry up to 500 olfactory receptor genes – far more than humans – and yet each smell-sensing neuron must choose just one to switch on. How do they do it?

Different routes to genetic order

In fruit flies, the fate of each receptor neuron is hardwired: every neuron is preassigned one odor gene.

In mice, which have over 1,000 odorant receptors, each neuron makes a random pick – but elaborate feedback wiring ensures that once one receptor turns on, all others stay off.

Ants, with several hundred receptors arranged in dense genomic neighborhoods or “clusters,” posed a tougher question: how can a cell activate the right gene without accidentally turning on its neighbors?

Tracing steps through DNA

The NYU team began by mapping gene activity cell by cell across ant olfactory neurons. A peculiar pattern emerged inside big receptor clusters.

While some cells expressed only the final gene in a cluster, others expressed the last two and still others the last three – like steps on a staircase.

That odd progression hinted at a physical mechanism sweeping through the cluster rather than a neat on/off switch at a single gene.

The bulldozer behind ant order

Under normal circumstances, transcription – the process of copying DNA instructions into RNA – halts at the end of each gene. Not here.

In ant receptor clusters, the copying machinery keeps rolling past the stop sign, plowing into downstream genes. Sieriebriennikov likens it to a “biological bulldozer” that runs through the fence and onto neighboring plots.

The effect is decisive. Runaway transcription occupies the DNA real estate downstream, blocking those genes from activating in the same cell. When a cell chooses one receptor gene, it effectively silences everything beyond it in the cluster.

Ants’ genetic brakes in action

That still left half the puzzle: what stops the genes before the chosen receptor? The team found the mirror-image move.

Once picked, the active receptor gene also produces an RNA transcript in the opposite direction – an antisense strand – that heads upstream. Think of it as the bulldozer reversing back through the cluster. That reverse run blocks transcription from firing at upstream genes, closing the door behind the chosen receptor.

The result is a self-enforcing system. A neuron’s chance selection of one receptor gene sets off a chain reaction that turns off every neighbor, both ahead and behind.

“The ‘runaway bulldozer’ is not an economical way of controlling genes,” Sieriebriennikov said. “But when nature finds a solution that relies on chance and does its purpose, it stays.”

Ants and humans converge

Claude Desplan, the study’s senior author, calls the mechanism “beautiful yet unexpected.” It’s also strangely familiar.

Human brains rely on protocadherin genes – a large, clustered family that helps neurons wire to the right partners – to follow their own “one gene per neuron” rule. Those clusters use antisense transcription to enforce exclusivity, too.

“This is a striking case of convergent evolution,” Sieriebriennikov noted. Ants and humans are distant branches on the tree of life, but faced with the same engineering problem – one choice, many options – evolution has arrived at similar logic.

Clusters that demand precision

The ant genome packs odor genes into clusters, some containing up to 59 genes, rather than scattering them randomly.

Clustering creates a coordination problem – any leakage in control risks multiple receptors turning on in the same neuron, garbling the chemical code the brain relies on. The bulldozer/antisense system is a physical, low-level way to guarantee exclusivity without preprogramming the fate of each neuron or building a complex feedback circuit.

It also explains that staircase signature the team saw. Depending on where transcription starts, the bulldozer can silence variable stretches of the cluster, creating cells that express only the last gene, or the last two, or the last three.

This is not an esoteric wiring diagram. Ant society runs on pheromones. If receptor choice fails, communication fails.

The study links molecular order to social order. The colony’s sophisticated division of labor, defense, and foraging depends on millions of neurons each making a single, clean genetic choice.

After this choice is made, it is enforced across a crowded neighborhood of similar genes.

Lessons from an ant’s genome

Researchers broaden a core rule of sensory biology, showing that “one receptor, one neuron” can arise through fate maps (flies), complex random-choice locks (mice), or mechanical sweep-and-silence tactics (ants).

It also reframes how scientists think about gene clusters. Sometimes, brute-force transcriptional read-through and antisense traffic are not accidents or noise, but rather the control system.

That perspective may matter beyond smell. Clustered gene families control wiring specificity, immune recognition, even aspects of development.

The ant solution suggests nature periodically reaches for the same toolkit – chance selection plus physical silencing – when diversity and exclusivity must coexist.

Keeping order in the chaos

For Sieriebriennikov, the final lesson is methodological. The staircase pattern initially looked like an artifact. It wasn’t.

“You might assume weird signals in the data are just noise,” he said. “However, when we pay attention to the unusual, weirdness gets explained, leading to interesting discoveries.”

In this case, curiosity about an odd pattern cracked a long-standing puzzle: how an ant’s nose keeps order in a crowd of hundreds.

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