Unique Mechanism of Scent Receptor Gene Selection in Ants

Researchers at Rockefeller University have uncovered a unique mechanism in clonal raider ants that allows each sensory neuron to express only one odor receptor gene from a library of hundreds. This mechanism, distinct from those found in flies or mammals, relies on transcriptional interference, where surrounding genes are silenced once a single receptor gene is selected.

Ants and the Scent-Based Society

The chemical communication system of ants plays a crucial role in their social lives, using pheromones to guide ants to food, warn them of dangers, and regulate colony rhythms. This system is based on a simple rule: one receptor per neuron.

The ant genome contains hundreds of odor receptor genes, with each receptor potentially dedicated to a specific chemical. If a neuron expressed more than one receptor at a time, the messages reaching the brain would be confused, hindering the ants’ ability to accurately identify scents.

The Unique Gene Selection Mechanism

Scientists have discovered the process by which a single receptor gene is chosen from the large gene library in ants. Researchers found that when a neuron activates the selected receptor gene, it doesn’t stop there. Instead, RNA polymerase continues transcription beyond the usual endpoint of the gene, leading to the silencing of surrounding genes.

These extended transcripts remain trapped in the nucleus, resulting in the silencing of neighboring genes. Simultaneously, the neuron also produces antisense transcripts, which act as a barrier to silence other potentially activated genes.

Applications to Other Species

The team confirmed that this same mechanism operates in other social insects, such as Indian jumping ants and honeybees. These findings suggest that many insects, both social and non-social, may use transcriptional interference to maintain a 1:1 ratio between receptors and neurons.

The results indicate that this mechanism might be more widely distributed among other insect species with a large number of odor receptor genes.

Conclusion

This study opens new avenues for understanding how genes are regulated in living organisms, especially in social insects. This unique mechanism helps maintain the individual identity of each neuron, enabling ants to quickly adapt to environmental changes and expand their olfactory range. This discovery not only solves a long-standing mystery in insect biology but also offers a general strategy that genomes might use to regulate large families of genes.