Understanding the molecular mechanisms of thermo- and hygro- sensation in Drosophila
Creators: name: Sarkissian, Tatevik
Publisher: name: Brandeis University
Year: 2026
Subjects: Drosophila
humidity
hygrosensation
Ionotropic Receptors
temperature
thermosensation

description: Temperature and humidity are ubiquitous sensory stimuli that are present during the detection of all other sensory cues. Thermosensation is critical for maintaining optimal body temperatures and avoiding thermal extremes. Hygrosensation (the ability to detect humidity) is a sensory modality that is important for insects like flies and mosquitoes, whose large surface- area-to-volume ratios render them particularly vulnerable to inundation or dehydration due to changes in the relative humidity of their surroundings. Disease vectors such as mosquitoes also use temperature and humidity as cues for host-seeking and blood feeding.Despite their importance in many systems, we lack a comprehensive understanding of the molecular and cellular components that mediate the detection and integration of thermosensory and hygrosensory information. Drosophila provide us with a simple model system where we can probe the molecular and cellular mechanisms of thermo- and hygro-sensation. Prior work in our lab has identified some of the molecular and cellular receptors that contribute to temperature (thermo-) and humidity (hygro-) sensation. However, current work suggests that additional thermo- and hygro-receptors remain to be identified. Furthermore, how these receptors detect temperature and humidity remain largely unknown. Over the course of this thesis work, I initially participated in a collaborative effect that used connectomics to obtain a detailed synaptic-level wiring diagram of the initial layers of the thermo- and hygro-sensors. This included generating a more comprehensive inventory of the antennal neurons that transmit thermo- and hygro-sensory information to the brain, revealing previously unappreciated subgroups of putative thermo- and/or hygro-sensory neurons. My subsequent efforts have focused on using cell-specific RNA- sequencing to further define the molecular characteristics of these neurons and to investigate the mechanisms through which they detect and transmit sensory information. This work has led to two main areas of investigation. First, it has led to the identification of a previously unstudied class of thermosensory neurons whose responsiveness to temperature depends on the activity of an Odorant Receptor (OR), a class of receptor previously implicated in chemical sensation. Further investigation has led to discovery that this OR, unlike other dipteran ORs described to date, does not require the Odorant Receptor co-Receptor (ORCO) for many of its activities. Second, this work has identified a small set of G-Protein Coupled Receptors (GPCRs) that are expressed in thermosensory neurons and whose functions are implicated in controlling temperature avoidance behavior. Together, this work has used a combination of molecular, genetic, physiological, behavioral, and transcriptomic approaches to define new classes of peripheral thermo- and hygro-sensory neurons and to discover new classes of molecular receptors involved in thermosensation in Drosophila melanogaster.