Remote homolog detection places insect chemoreceptors in a cryptic protein superfamily spanning the tree of life.

Many proteins exist in the so-called "twilight zone" of sequence alignment, where low pairwise sequence identity makes it difficult to determine homology and phylogeny. As protein tertiary structure is often more conserved, recent advances in ab initio protein folding have made structure-based identification of putative homologs feasible. We present a pipeline for the identification and characterization of distant homologs and apply it to 7-transmembrane-domain ion channels (7TMICs), a protein group founded by insect odorant and gustatory receptors.

Structural screens identify candidate human homologs of insect chemoreceptors and cryptic gustatory receptor-like proteins.

Insect odorant receptors and gustatory receptors define a superfamily of seven transmembrane domain ion channels (referred to here as 7TMICs), with homologs identified across Animalia except Chordata. Previously, we used sequence-based screening methods to reveal conservation of this family in unicellular eukaryotes and plants (DUF3537 proteins) (Benton et al., 2020).

Chloride-dependent mechanisms of multimodal sensory discrimination and nociceptive sensitization in .

Individual sensory neurons can be tuned to many stimuli, each driving unique, stimulus-relevant behaviors, and the ability of multimodal nociceptor neurons to discriminate between potentially harmful and innocuous stimuli is broadly important for organismal survival. Moreover, disruptions in the capacity to differentiate between noxious and innocuous stimuli can result in neuropathic pain. larval class III (CIII) neurons are peripheral noxious cold nociceptors and innocuous touch mechanosensors; high levels of activation drive cold-evoked contraction (CT) behavior, while low levels of activation result in a suite of touch-associated behaviors.

Modality specific roles for metabotropic GABAergic signaling and calcium induced calcium release mechanisms in regulating cold nociception.

Calcium (Ca) plays a pivotal role in modulating neuronal-mediated responses to modality-specific sensory stimuli. Recent studies in reveal class III (CIII) multidendritic (md) sensory neurons function as multimodal sensors regulating distinct behavioral responses to innocuous mechanical and nociceptive thermal stimuli. Functional analyses revealed CIII-mediated multimodal behavioral output is dependent upon activation levels with stimulus-evoked Ca displaying relatively low vs.

Sweet sensors support stressed cell survival.

Gustatory receptors (Grs) are well known for their functions in sensory neurons in detecting food and toxins. An intriguing new study in PLOS Biology provides evidence for a role for Grs in Drosophila epithelia in protecting stressed cells from proteotoxicity.

Protocols for measuring cold-evoked neural activity and cold tolerance in Drosophila larvae following fictive cold acclimation.

Here, we outline protocols to study cold acclimation in Drosophila from a neurobiological perspective, starting with fictive cold acclimation using a custom-built optogenetics-housing apparatus we call the OptoBox. We also provide detailed steps for single-unit electrophysiological recordings from larval cold nociceptors and a high-throughput cold-tolerance assay. These protocols expand the toolkit for the study of insect cold acclimation and nociception.

Identification of a neural basis for cold acclimation in larvae.

Low temperatures can be fatal to insects, but many species have evolved the ability to cold acclimate, thereby increasing their cold tolerance. It has been previously shown that larvae perform cold-evoked behaviors under the control of noxious cold-sensing neurons (nociceptors), but it is unknown how the nervous system might participate in cold tolerance. Herein, we describe cold-nociceptive behavior among 11 drosophilid species; we find that the predominant cold-evoked larval response is a head-to-tail contraction behavior, which is likely inherited from a common ancestor, but is unlikely to be protective.

Dissecting the Molecular and Neural Circuit Bases of Behavior as an Introduction to Discovery-Driven Research; A Report on a Course-Based Undergraduate Research Experience.

Herein we discuss a Course-Based Undergraduate Research Experience (CURE) developed in order to engage novice undergraduates in active learning and discovery-driven original research. This course leverages the powerful genetic toolkits available for in order to investigate the cellular and molecular bases of cold nociception. Given the relatively inexpensive nature of rearing, a growing suite of publicly available neurogenomic data, large collections of transgenic stocks available through community stock centers, and 's highly stereotyped behaviors, this CURE design constitutes a cost-effective approach to introduce students to principles and techniques in genetics, genomics, behavioral neuroscience, research design, and scientific presentation.

Purinergic signaling is enhanced in the absence of UT-A1 and UT-A3.

ATP is an important paracrine regulator of renal tubular water and urea transport. The activity of P2Y , the predominant P2Y receptor of the medullary collecting duct, is mediated by ATP, and modulates urinary concentration. To investigate the role of purinergic signaling in the absence of urea transport in the collecting duct, we studied wild-type (WT) and UT-A1/A3 null (UT-A1/A3 KO) mice in metabolic cages to monitor urine output, and collected tissue samples for analysis.

Transient receptor potential channels: current perspectives on evolution, structure, function and nomenclature.

The transient receptor potential superfamily of ion channels (TRP channels) is widely recognized for the roles its members play in sensory nervous systems. However, the incredible diversity within the TRP superfamily, and the wide range of sensory capacities found therein, has also allowed TRP channels to function beyond sensing an organism's external environment, and TRP channels have thus become broadly critical to (at least) animal life. TRP channels were originally discovered in and have since been broadly studied in animals; however, thanks to a boom in genomic and transcriptomic data, we now know that TRP channels are present in the genomes of a variety of creatures, including green algae, fungi, choanoflagellates and a number of other eukaryotes.

Phylogenetics Identifies Two Eumetazoan TRPM Clades and an Eighth TRP Family, TRP Soromelastatin (TRPS).

Transient receptor potential melastatins (TRPMs) are most well known as cold and menthol sensors, but are in fact broadly critical for life, from ion homeostasis to reproduction. Yet, the evolutionary relationship between TRPM channels remains largely unresolved, particularly with respect to the placement of several highly divergent members. To characterize the evolution of TRPM and like channels, we performed a large-scale phylogenetic analysis of >1,300 TRPM-like sequences from 14 phyla (Annelida, Arthropoda, Brachiopoda, Chordata, Cnidaria, Echinodermata, Hemichordata, Mollusca, Nematoda, Nemertea, Phoronida, Priapulida, Tardigrada, and Xenacoelomorpha), including sequences from a variety of recently sequenced genomes that fill what would otherwise be substantial taxonomic gaps.

An assay for chemical nociception in larvae.

Chemically induced nociception has not yet been studied intensively in genetically tractable models. Hence, our goal was to establish a assay that can be used to study the cellular and molecular/genetic bases of chemically induced nociception. larvae exposed to increasing concentrations of hydrochloric acid (HCl) produced an increasingly intense aversive rolling response.

menthol sensitivity and the Precambrian origins of transient receptor potential-dependent chemosensation.

Transient receptor potential (TRP) cation channels are highly conserved, polymodal sensors which respond to a wide variety of stimuli. Perhaps most notably, TRP channels serve critical functions in nociception and pain. A growing body of evidence suggests that transient receptor potential melastatin (TRPM) and transient receptor potential ankyrin (TRPA) thermal and electrophile sensitivities predate the protostome-deuterostome split (greater than 550 Ma).

Chronic lithium treatment induces novel patterns of pendrin localization and expression.

Prolonged lithium treatment is associated with various renal side effects and is known to induce inner medullary collecting duct (IMCD) remodeling. In animals treated with lithium, the fraction of intercalated cells (ICs), which are responsible for acid-base homeostasis, increases compared with renal principal cells (PCs). To investigate the intricacies of lithium-induced IMCD remodeling, male Sprague-Dawley rats were fed a lithium-enriched diet for 0,1, 2, 3, 6, 9, or 12 wk.

The TRP Channels Pkd2, NompC, and Trpm Act in Cold-Sensing Neurons to Mediate Unique Aversive Behaviors to Noxious Cold in Drosophila.

The basic mechanisms underlying noxious cold perception are not well understood. We developed Drosophila assays for noxious cold responses. Larvae respond to near-freezing temperatures via a mutually exclusive set of singular behaviors-in particular, a full-body contraction (CT).

Absence of PKC-alpha attenuates lithium-induced nephrogenic diabetes insipidus.

Lithium, an effective antipsychotic, induces nephrogenic diabetes insipidus (NDI) in ∼40% of patients. The decreased capacity to concentrate urine is likely due to lithium acutely disrupting the cAMP pathway and chronically reducing urea transporter (UT-A1) and water channel (AQP2) expression in the inner medulla. Targeting an alternative signaling pathway, such as PKC-mediated signaling, may be an effective method of treating lithium-induced polyuria.