Ionotropic Receptors Specify the Morphogenesis of Phasic Sensors Controlling Rapid Thermal Preference in Drosophila.

Thermosensation is critical for avoiding thermal extremes and regulating body temperature. While thermosensors activated by noxious temperatures respond to hot or cold, many innocuous thermosensors exhibit robust baseline activity and lack discrete temperature thresholds, suggesting they are not simply warm and cool detectors. Here, we investigate how the aristal Cold Cells encode innocuous temperatures in Drosophila. We find they are not cold sensors but cooling-activated and warming-inhibited phasic thermosensors that operate similarly at warm and cool temperatures; we propose renaming them "Cooling Cells." Unexpectedly, Cooling Cell thermosensing does not require the previously reported Brivido Transient Receptor Potential (TRP) channels. Instead, three Ionotropic Receptors (IRs), IR21a, IR25a, and IR93a, specify both the unique structure of Cooling Cell cilia endings and their thermosensitivity. Behaviorally, Cooling Cells promote both warm and cool avoidance. These findings reveal a morphogenetic role for IRs and demonstrate the central role of phasic thermosensing in innocuous thermosensation. VIDEO ABSTRACT.

Ionotropic Receptor-dependent moist and dry cells control hygrosensation in Drosophila.

Insects use hygrosensation (humidity sensing) to avoid desiccation and, in vectors such as mosquitoes, to locate vertebrate hosts. Sensory neurons activated by either dry or moist air ('dry cells' and 'moist cells') have been described in many insects, but their behavioral roles and the molecular basis of their hygrosensitivity remain unclear. We recently reported that Drosophila hygrosensation relies on three Ionotropic Receptors (IRs) required for dry cell function: IR25a, IR93a and IR40a (Knecht et al., 2016). Here, we discover Drosophila moist cells and show that they require IR25a and IR93a together with IR68a, a conserved, but orphan IR. Both IR68a- and IR40a-dependent pathways drive hygrosensory behavior: each is important for dry-seeking by hydrated flies and together they underlie moist-seeking by dehydrated flies. These studies reveal that humidity sensing in Drosophila, and likely other insects, involves the combined activity of two molecularly related but neuronally distinct hygrosensing systems.

Distinct combinations of variant ionotropic glutamate receptors mediate thermosensation and hygrosensation in Drosophila.

Ionotropic Receptors (IRs) are a large subfamily of variant ionotropic glutamate receptors present across Protostomia. While these receptors are most extensively studied for their roles in chemosensory detection, recent work has implicated two family members, IR21a and IR25a, in thermosensation in Drosophila. Here we characterize one of the most evolutionarily deeply conserved receptors, IR93a, and show that it is co-expressed and functions with IR21a and IR25a to mediate physiological and behavioral responses to cool temperatures. IR93a is also co-expressed with IR25a and a distinct receptor, IR40a, in a discrete population of sensory neurons in the sacculus, a multi-chambered pocket within the antenna. We demonstrate that this combination of receptors is required for neuronal responses to dry air and behavioral discrimination of humidity differences. Our results identify IR93a as a common component of molecularly and cellularly distinct IR pathways important for thermosensation and hygrosensation in insects.

The Touching Tail of a Mechanotransduction Channel.

In mechanotransduction, sensory receptors convert force into electrical signals to mediate such diverse functions as touch, pain, and hearing. In this issue of Cell, Zhang et al. present evidence that the fly NompC channel senses mechanical stimuli using its N-terminal tail as a tether between the cell membrane and microtubules.

A survey of hallucinogenic mushroom use, factors related to usage, and perceptions of use among college students.

BACKGROUND: Recreational usage and attitudes toward psilocybin-containing hallucinogenic mushrooms among college students are seldom explored. METHODS: We surveyed 882 randomly selected undergraduates at Skidmore College in upstate New York and quantified whether participants had ever used psilocybin mushrooms, their attitudes toward the drug, and polydrug use. RESULTS: There were 409 responses and 29.5% of the sample reported psilocybin use. Among users, the mean number of times they reported using mushrooms was 3.4 (mode=1). The top factors cited that influenced their decisions to try hallucinogenic mushrooms for the first time were 'curiosity', 'to achieve a mystical experience', and 'introspection'. Users and non-users had significantly different perceptions of mushrooms: non-users were more likely to say that hallucinogenic mushrooms were addictive and had the potential for abuse than users. Users did not believe that psilocybin negatively impacts their academics, mental health, or physical health, while non-users did. Both users and non-users of psilocybin reported high life-time use of alcohol (97% vs 96%, respectively), marijuana (98% vs 73%, respectively) and tobacco (82% vs 54%, respectively). Psilocybin users were significantly more likely to use other drugs such as cocaine, ecstasy, opiates, non-prescribed prescription drugs, opiates, and lysergic acid diethylamide (LSD) than non-users of psilocybin. CONCLUSION: This study uncovers important insights into hallucinogenic mushroom use by college students.