Resume: The Orco protein is crucial for the survival of olfactory neurons in ants. Mutating the orco gene in Harpegnathos saltator ants drastically reduced their number of olfactory neurons, affecting their social interactions.
This study highlights the importance of Orco in neural development and social communication in ants. Understanding these mechanisms can provide insight into sensory-mediated social behavior in both animals and humans.
Key Facts:
- Orcoprotein is vital for the development and survival of olfactory neurons in ants.
- Mutant ants lacking Orco experienced significant neuronal death and reduced social interactions.
- The study provides new insights into how sensory systems and social behavior in animals are connected.
Source: N.Y.U
Although scent plays a significant role in people’s social interactions—for example, signaling fear or creating proximity—scent is critical to ants.
Researchers from New York University and the University of Florida discovered that a key protein called Orco, essential for the function of olfactory cells, is also critical for cell survival in ants.
Their research showed that mutating the orco gen in Harpegnathos saltator jumping ants dramatically reduced the number of olfactory neurons, suggesting that Orco is necessary for the development and life of these cells.
The findings, published in Scientific progressprovide insight into the cellular and molecular basis of how animals socialize.
“Understanding how the nervous system develops is one of the most pressing challenges in modern neuroscience,” said Bogdan Sieriebriennikov, a postdoctoral researcher in NYU’s Department of Biology and the study’s first author.
Perceiving odor and mutated ants
Ants have evolved about 400 scent receptors – a number closer to humans than most other insects – thanks to their use of pheromone communication.
“Ants, like humans, are highly social and exhibit cooperative social behavior, thus providing an ideal system to study sensory-mediated social behavior,” explains Hua Yan, assistant professor of biology at the University of Florida and senior author of the study , out.
“Extensive odor receptor genes enable ants to ‘talk’ to each other in a large society with hundreds, thousands or even a million individuals.”
Even for humans, who rely on other senses for communication, smell is essential.
“Loss of function of olfactory receptor neurons leads to deficits in olfactory perception and is often associated with social isolation, neurological disorders such as schizophrenia and social disorders such as autism,” Yan added.
To better understand how ants’ sense of smell affects their social interactions, NYU researchers previously created the first genetically engineered ants by using CRISPR to orco gene. These ‘mutant’ ants, which lacked the Orco protein, experienced changes in their olfactory organs and had difficulty interacting.
“We found that the antennae – the ant’s ‘nose’ – had very few cells. They were almost empty, indicating that the odor-sensing cells were absent in the mutant ants,” Yan said.
The survival of neurons depends on Orco
In their new study in Scientific progressthe researchers used single-nucleus gene expression profiling of ant antennae and fluorescence microscopy to analyze olfactory cell development. It turned out that mutant insects without Orco lose most of their olfactory neurons before adulthood.
“The cells appear to be made normally and begin to develop – they grow, change shape and switch on certain genes that they will need later, such as olfactory receptors,” Sieriebriennikov said.
“Once the developing cells turn on the odor receptors, they quickly begin to die in massive quantities.”
This neuronal death may be the result of stress. Because the odor receptors in the mutant ants cannot form a complex with Orco to travel to the cell membrane, the newly made receptors clog the organelles, leading to stress and death.
Such neuronal death may also show patterns specific to social insects. “Until now, these unique processes have not been found in solitary insects and may provide important evidence of the evolution of neural development to adapt to the expansion of olfactory receptor genes,” said Kayli Sieber, a doctoral candidate at the University of Florida and the co. -first author of the study.
Interestingly, some olfactory receptors survived even without Orco. The cells in which they were present also expressed other types of receptors, suggesting that the activity they facilitate is essential for neuronal development.
“Some neurons need to ‘fire’ periodically to develop properly. Without Orco, the olfactory cells did not ‘fire’ and complete their development, which led to their death,” says Sieriebriennikov.
The researchers also found that some olfactory receptors are present in non-olfactory cells, such as mechanosensory neurons that detect motion and glia, which wrap around neurons and help them function.
This may be due to imperfect regulation of genes, causing odor receptors to be accidentally activated by nearby genomic regions that normally regulate other genes in other cells. Alternatively, the receptors may have a novel function in these cells, such as the olfactory receptors found in glia C. elegans worms or human sperm.
“Switching on odor receptor genes in the cells that have no odor perception could be completely useless for the organism – but then again, evolution tends to take advantage of such mistakes to give existing genes new functions, so perhaps there is an exciting new role for the organism.” of odor receptors in non-odor cells that we will discover in the future,” said Sieriebriennikov.
“Our findings advance our understanding of the sensory systems of social insects, including the olfactory neural development that provides a framework for social communication,” says Yan.
Financing: Other authors of the study include Olena Kolumba, Jakub Mlejnek and Shadi Jafari. This research was supported by the National Institutes of Health (R01-DC020203, T32-DC015994), the National Science Foundation Industry-University Cooperative Research Center for Arthropod Management Technologies (#IIP1821914), and the Human Frontier Science Program (LT000010/2020- L ).
About this research news in neuroscience and genetics
Author: Rachel Harrison
Source: N.Y.U
Contact: Rachel Harrison – NYU
Image: The image is credited to Neuroscience News
Original research: Open access.
“Orco-dependent survival of odorant receptor neurons in ants” by Bogdan Sieriebriennikov et al. Scientific progress
Abstract
Orco-dependent survival of odorant receptor neurons in ants
Smell is essential for complex social behavior in insects. To distinguish complex social signals, ants evolved a greater number olfactory receptor (Or) genes.
Mutations in the obligate odorous co-receptor gene orco lead to the loss of ~80% of glomeruli in the antennal lobe in the jumping ant Harpegnathos saltator. However, the cellular mechanism remains unclear.
Here we demonstrate massive apoptosis of odorant receptor neurons (ORNs) in the mid to late stages of pupal development, possibly due to ER stress in the absence of Orco.
Further bulk and single-nucleus transcriptome analysis shows that, although most orco-expressing ORNs die in orco Mutants, a small part of them survive: they express themselves ionotropic receptor (Ir) genes that form IR complexes.
Moreover, we found that some Or genes are expressed in mechanosensory neurons and non-neuronal cells, possibly due to leaky regulation of nearby non-neuronal cells.Or genes.
Our findings provide a comprehensive overview of ORN development and Or expression H. saltator.