Dynamics and roles of aminergic neurons in pheromone processing.

2020 Fiscal Year Research-status Report

• Project/Area Number: 19K06895
• Research Institution: Institute of Physical and Chemical Research
• Principal Investigator: MERCIER DAMIEN 国立研究開発法人理化学研究所, 脳神経科学研究センター, 客員研究員 (60604840)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: Bioluminescence / calcium imaging / pheromone / Drosophila

Outline of Annual Research Achievements

Aminergic neurons are reported to encode various types of information including those related to motivation and values. However, how these neurons dynamically change their activity in an ethological context to encode such information is poorly understood. Here, we aim to examine the dynamics of aminergic neural activity while the animal is engaged in pheromone communication. We will study this using Drosophila melanogaster and focus on the communication mediated by pheromones contained in olfactory landmarks that are deposited by individual animals. Furthermore, we aim to characterize the context-dependent effects of olfactory landmarks on neural activity and behavior as the content of fecal materials deposited by the flies is reported to change depending on the age and social environment.
This year, we conducted a gas chromatography/mass spectrometry (GC/MS) analysis to quantify the amount of cuticular hydrocarbons contained in olfactory landmarks. By optimizing the sample collection procedure and the parameters for GC/MS analysis, we were able to detect multiple major cuticular hydrocarbons in single olfactory landmarks. Using a classification approach, we found that information about the identity of both sex and age of the landmark depositor can be decoded from the content of landmarks.
To examine how dopamine neurons respond to these pheromone landmarks, we developed a protocol to image the activity of all the dopamine neurons in the secondary olfactory processing center, using a two-photon microscope, while continuing to develop the bioluminescence recording method.

Current Status of Research Progress

2: Research has progressed on the whole more than it was originally planned.

Reason

Because we were able to quantify the amount of major cuticular hydrocarbons in single olfactory landmarks, and to develop a protocol to image the activity of all the dopamine neurons in the secondary olfactory processing center, using a two-photon microscope.

Strategy for Future Research Activity

We will investigate whether individual male flies show differential level of attraction to landmarks deposited by a conspecific of different age. If so, this would suggest that the fly is using the information about age contained in pheromone to communicate with each other. We will also record the response of dopamine neurons and olfactory neurons to landmarks to investigate the neural representations of pheromones. Finally, we will continue to develop a novel calcium indicator based on a different bioluminescence molecule to record from specific Dopaminergic neurons.

Causes of Carryover

Because we are still developing a novel calcium indicator based on a different bioluminescence molecule, we decided to roll over some amount to the next fiscal year to be used for the generation of transgenic flies carrying the novel construct.