Complexity of the ant brain revealed for the first time at the cellular level using single-cell technology

Summary: Using single-cell technology, researchers are discovering how the social division of labor in an ant colony is reflected in the functional specialization of the ant brain at the cellular level.

Source: BGI Group

International researchers led by the Chinese company BGI-Research have used single-cell technology to study the brains of ants, explaining for the first time how the social division of labor within ant colonies is reflected in the functional specialization of their brains at cellular level.

In a study titled, “A single-cell transcriptomic atlas tracking the neural basis of division of labor in an ant superorganism,” published in Nature Ecology and Evolution, scientists from BGI Group’s BGI-Research, Kunming Institute of Zoology, Chinese Academy of Sciences, University of Copenhagen and others applied BGI’s DNBeLab single-cell library platform to obtain more than 200,000 single-nucleus transcriptomes from pharaoh ant brains and constructed transcriptome map unicellular covering all adult phenotypes of this ant species: workers, males, gynes. (virgin queens) and queens.

Ants are one of the most successful organisms on earth, having existed for over 140 million years. The biomass (determined by multiplying an estimated population by the average weight of its limbs) of ants is estimated to be similar to the biomass of humans. The success of ants is generally attributed to their remarkable social behavior with a clear reproductive division of labor.

Ant colonies have been conceptualized as superorganisms for over a century. Now taking advantage of single cell technology, scientists have been able to systematically determine cell complexity in an ant’s brain and assess the difference in brain cell composition between individuals in the same colony.

“Our findings suggest that the functional specialization of their brains appears to be a mechanism underlying the division of social tasks in individual ants,” says Dr. Qiye Li, first author of the paper and researcher at BGI-Research. “We humans learn and train to do different jobs, while ants are born with a specific role in their colony.”

The research team found that the brains of worker and male ants are extremely specialized and highly complementary. Neurons responsible for learning, memory and olfactory information processing are particularly abundant in workers, while the abundance of optic lobe cells responsible for visual information processing is very low. This trend is reversed in the brains of male ants where there is an abundance of optic lobe cells, but fewer neurons for olfactory processing, learning and memory.

“These results provide good support for our laboratory observations that pharaoh ants are responsible for all colony maintenance tasks that require versatile brains, while males do not participate in any colony maintenance tasks because their sole function is to find and inseminate a virgin queen.” said Dr. Weiwei Liu, researcher at the Kunming Institute of Zoology, Chinese Academy of Sciences, and co-corresponding author of the paper.

The analysis also identified significant changes in the brains of the gynes when they turned into queens after mating. For example, the abundance of optic lobe cells decreased as queens adapted to the darkness of the nest, while dopaminergic neurons and sheathing glia increased, which may explain queen fecundity and longevity. .

“This is the first single-cell atlas that covers all social roles in an ant colony. Its achievement benefits from the development of massively parallel single-cell profiling technology with high sensitivity and accuracy at low cost,” said Dr. Chuanyu Liu, corresponding co-author and researcher at BGI-Research.

By comparing the brain cells of the pharaoh ant and Drosophila fruit fly, the researchers also found many types of cells conserved in insect brains. For example, a population of optic lobe cells in Drosophila responsible for detecting the movement of objects during courtship also exists in ants and is particularly abundant in males.

Ants are one of the most successful organisms on earth, having existed for over 140 million years. Image is in public domain

The molecular signature and spatial location of these cells are very similar in the two distant insects, suggesting that these cells likely play a conserved role in regulating male mating behavior in insects regardless of their sociability.

“This study helps us understand the complexity of the ant brain and how complementary specialization in the brain enables ants within a colony to function as a superorganism,” said corresponding co-author Professor Guojie Zhang. from the Center for Evolutionary and Organic Biology Research, School of Medicine, Zhejiang University.

“The brains of different castes and sexes are specialized in different directions and complementary to each other, allowing the entire ant colony to perform all functions including reproduction, brood rearing , foraging and defense.

“This superorganic life strategy allowed ants to flourish over 140 million years of competition and eventually become a highly dominant animal group on Earth.”

Ethics approval has been received for this research.

About this neuroscience research news

Author: Richard Li
Source: BGI Group
Contact: Richard Li – BGI Group
Image: Image is in public domain

Original research: Free access.
“A single-cell transcriptomic atlas tracing the neural basis of division of labor in an ant superorganism” by Qiye Li et al. Nature ecology and evolution

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Summary

A single-cell transcriptomic atlas tracing the neural basis of division of labor in an ant superorganism

Ant colonies with a permanent division of labor between castes and very distinct gender roles have been conceptualized as superorganisms, but the cellular and molecular mechanisms that mediate caste/sex-specific behavioral specialization have remained obscure.

Here, we characterized the brain cell repertoire of queens, gynes (virgin queens), workers, and males of Monomorium pharaonis obtaining 206,367 single core transcriptomes.

Contrary to Drosophilamushroom body Kenyon cells are abundant in ants and display great diversity, with most subtypes being enriched in the brains of workers, the evolutionarily derived caste.

Male brains are as specialized as worker brains, but with opposite trends in cellular composition with higher abundances of all optic lobe neuronal subtypes, while gyne and queen brain composition remained generalized, reminiscent solitary ancestors.

Differentiation of roles from virgin gynes to inseminated queens induces abundance changes in approximately 35% of cell types, indicating active neurogenesis and/or programmed cell death during this transition.

We also identified insemination-induced cellular changes likely associated with reproductive caste longevity and fecundity, including increases in sheathing glia and a dopamine-regulated cell population. Dh31– expressing neurons.

We conclude that permanent caste differentiation and extreme sexual differentiation induced major changes in the neural circuitry of ants.

Sharon D. Cole