Ultrastructure and Function of Insect Thermo- And Hygroreceptors

Altner, Helmut; Loftus, Richard

doi:10.1146/annurev.en.30.010185.001421

Cited by 313 publications

(129 citation statements)

References 31 publications

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“…Previous work has pointed to the fly antenna as a key organ for the detection of humidity in insects [4, 5]. Most sensory neurons of the antenna express receptor proteins of the odorant receptor (OR) [10, 11], or ionotropic receptor (IR) families [12], and broadly expressed co-receptors are typically required for function: Orco for ORs [13] and IR8a or IR25a for the IRs [14].…”

Section: Resultsmentioning

confidence: 99%

“…Hygrosensation has previously been proposed to comprise a thermosensory component [5, 16]. Hence, we next set out to determine if IR21a, IR25a, IR93a and IR40a also mediate temperature responses.…”

Section: Resultsmentioning

confidence: 99%

“…Insects in particular use humidity cues to navigate the environment, and previous work suggests the existence of specific sensory mechanisms to detect favorable humidity ranges [2–5]. Yet, the molecular and cellular basis of humidity sensing (hygrosensation) remains poorly understood.…”

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confidence: 99%

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Humidity Sensing in Drosophila

et al. 2016

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Summary Environmental humidity influences the fitness and geographic distribution of all animals [1]. Insects in particular use humidity cues to navigate the environment, and previous work suggests the existence of specific sensory mechanisms to detect favorable humidity ranges [2–5]. Yet, the molecular and cellular basis of humidity sensing (hygrosensation) remains poorly understood. Here, we describe genes and neurons necessary for hygrosensation in the vinegar fly Drosophila melanogaster. We find that members of the Drosophila genus display species-specific humidity preferences related to conditions in their native habitats. Using a simple behavioral assay, we find that the ionotropic receptors IR40a, IR93a and IR25a are all required for humidity preference in D. melanogaster. Yet, while IR40a is selectively required for hygrosensory responses, IR93a and IR25a mediate both humidity and temperature preference. Consistent with this, the expression of IR93a and IR25a includes thermosensory neurons of the arista. In contrast, IR40a is excluded from the arista, but expressed (and required) in specialized neurons innervating pore-less sensilla of the sacculus, a unique invagination of the third antennal segment. Indeed, calcium imaging shows that IR40a neurons directly respond to changes in humidity, and IR40a knockdown or IR93a mutation reduced their responses to stimuli. Taken together, our results suggest that the preference for a specific humidity range depends on specialized sacculus neurons, and that the processing of environmental humidity can happen largely in parallel to that of temperature.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Humidity Sensing in Drosophila

et al. 2016

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“…In E. messoria and Heliotis amigera this sensillum appears to possess a laminated outer dendritic segment. Such laminated dendrites have been associated with cold receptors (see Altner and Loftus 1985), as well as with CO 2 receptors (Chu-wang et al 1975; McIver and Siemicki 1984; Lee et al 1985; Bogner et al 1986). In Y. cagnagellus both cold receptors and CO 2 receptors were found.…”

Section: Discussionmentioning

confidence: 99%

Olfactory receptors on the maxillary palps of small ermine moth larvae: evolutionary history of benzaldehyde sensitivity

Roessingh

Menken

2007

J Comp Physiol A

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In lepidopterous larvae the maxillary palps contain a large portion of the sensory equipment of the insect. Yet, knowledge about the sensitivity of these cells is limited. In this paper a morphological, behavioral, and electrophysiological investigation of the maxillary palps of Yponomeuta cagnagellus (Lepidoptera: Yponomeutidae) is presented. In addition to thermoreceptors, CO 2 receptors, and gustatory receptors, evidence is reported for the existence of two groups of receptor cells sensitive to plant volatiles. Cells that are mainly sensitive to (E)-2-hexenal and hexanal or to (Z)-3-hexen-1-ol and 1-hexanol were found. Interestingly, a high sensitivity for benzaldehyde was also found. This compound is not known to be present in Euonymus europaeus, the host plant of the monophagous Yponomeuta cagnagellus, but it is a prominent compound in Rosaceae, the presumed hosts of the ancestors of Y. cagnagellus. To elucidate the evolutionary history of this sensitivity, and its possible role in host shifts, feeding responses of three Yponomeuta species to benzaldehyde were investigated. The results conWrm the hypothesis that the sensitivity to benzaldehyde evolved during the ancestral shift from Celastraceae to Rosaceae and can be considered an evolutionary relict, retained in the recently backshifted Celastraceae-specialist Y. cagnagellus.

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“…The antenna, a peripheral organ, is recognized as a temperature-sensing organ in many insects, including flies , based on its anatomical features and on physiological evidence (Altner et al, 1981; Altner and Loftus, 1985; Shanbhag et al, 1995; Sayeed and Benzer, 1996; Zars, 2001). In flies, the TRPP protein Brivido, which mediates cold detection, is expressed in the 3 rd antennal segments (Gallio et al, 2011), and several thermoTRP channels are expressed in the 2 nd antennal segments (Sun et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

Temperature Integration at the AC Thermosensory Neurons inDrosophila

et al. 2013

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Temperature sensation has a strong impact on animal behavior and is necessary for animals to avoid exposure to harmful temperatures. It is now well known that thermoTRP (Transient Receptor Potential) channels in thermosensory neurons detect a variable range of temperature stimuli. However, little is known about how a range of temperature information is relayed and integrated in the neural circuits. Here, we show novel temperature integration between two warm inputs via Drosophila TRPA channels, TRPA1 and Pyrexia (Pyx). The internal AC (Anterior Cell) thermosensory neurons, which express TRPA1, detect warm temperatures and mediate temperature preference behavior. We found that the AC neurons were activated twice when subjected to increasing temperatures. The first response was at ~25°C via TRPA1 channel, which is expressed in the AC neurons. The second response was at ~27°C via the 2nd antennal segments, indicating that the 2nd antennal segments are involved in the detection of warm temperatures. Further analysis reveals that pyx-Gal4 expressing neurons have synapses on the AC neurons and that mutation of pyx eliminates the second response of the AC neurons. These data suggest that AC neurons integrate both their own TRPA1-dependent temperature responses and a Pyx-dependent temperature response from the 2nd antennal segments. Our data reveal the first identification of temperature integration, which combines warm temperature information from peripheral to central neurons and provides the possibility that temperature integration is involved in the plasticity of behavioral outputs.

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Ultrastructure and Function of Insect Thermo- And Hygroreceptors

Cited by 313 publications

References 31 publications

Humidity Sensing in Drosophila

Humidity Sensing in Drosophila

Olfactory receptors on the maxillary palps of small ermine moth larvae: evolutionary history of benzaldehyde sensitivity

Temperature Integration at the AC Thermosensory Neurons inDrosophila

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