scholarly journals Molecular Modelling of Oligomeric States of DmOR83b, an Olfactory Receptor in D. Melanogaster

2012 ◽  
Vol 6 ◽  
pp. BBI.S8990 ◽  
Author(s):  
K. Harini ◽  
R. Sowdhamini
Keyword(s):  
Olfactory Receptor ◽  
Olfactory Receptors ◽  
Insect Species ◽  
Agricultural Pests ◽  
Negative Effects ◽  
C Terminus ◽  
Receptor Neurons ◽  
Medical Importance ◽  
G Protein Coupled ◽  
Made In

After the discovery of the complete repertoire of D. melanogaster Olfactory Receptors (ORs), candidate ORs have been identified from at least 12 insect species from four orders (Coleoptera, Lepidoptera, Diptera, and Hymenoptera), including species of economic or medical importance. Although all ORs share the same G-protein coupled receptor structure with seven transmembrane domains, they share poor sequence identity within and between species, and have been identified mainly through genomic data analyses. To date, D. melanogaster remains the only insect species where ORs have been extensively studied, from expression pattern establishment to functional investigations. These studies have confirmed several observations made in vertebrates: one OR type is selectively expressed in a subtype of olfactory receptor neurons, and one olfactory neuron expresses only one type of OR. The olfactory mechanism, further, appears to be conserved between insects and vertebrates. Understanding the function of insect ORs will greatly contribute to the understanding of insect chemical communication mechanisms, particularly with agricultural pests and disease vectors, and could result in future strategies to reduce their negative effects. In this study, we propose molecular models for insect olfactory receptor co-receptor OR83b and its possible functional oligomeric states. The functional similarity of OR83b to GPCRs and ion channels has been exploited for understanding the structure of OR83b. We could observe that C-terminal region (TM4-7) of OR83b is involved in homodimer amd heterodimer formation (with OR22a) which suggests why C-terminus of insect ORs are highly conserved across different species. We also propose two possible ion channel pathways in OR83b: one formed by TM4-5 region with intracellular pore-forming domain and the other formed by TM5-6 with extracellular pore forming domain using analysis of the electrostatics distribution of the pore forming domain.

Internalization of G Protein-Coupled Receptors in Single Olfactory Receptor Neurons

1999 ◽  
Vol 72 (2) ◽  
pp. 541-548 ◽  
Author(s):  
Michele L. Rankin ◽  
Rebecca S. Alvania ◽  
Evanna L. Gleason ◽  
Richard C. Bruch
Keyword(s):  
G Protein ◽  
Olfactory Receptor ◽  
G Protein Coupled Receptors ◽  
Olfactory Receptor Neurons ◽  
Receptor Neurons ◽  
G Protein Coupled

scholarly journals Inhibitory Odorant Signaling in Mammalian Olfactory Receptor Neurons

2010 ◽  
Vol 103 (2) ◽  
pp. 1114-1122 ◽  
Author(s):  
Kirill Ukhanov ◽  
Elizabeth A. Corey ◽  
Daniela Brunert ◽  
Katharina Klasen ◽  
Barry W. Ache
Keyword(s):  
Olfactory Receptor ◽  
Olfactory Receptor Neurons ◽  
Electrophysiological Response ◽  
Cellular Processes ◽  
Receptor Neurons ◽  
Phosphoinositide 3 Kinase ◽  
Mixture Suppression ◽  
G Protein Coupled ◽  
Kinetics Of

Odorants inhibit as well as excite olfactory receptor neurons (ORNs) in many species of animals. Cyclic nucleotide-dependent activation of canonical mammalian ORNs is well established but it is still unclear how odorants inhibit these cells. Here we further implicate phosphoinositide-3-kinase (PI3K), an indispensable element of PI signaling in many cellular processes, in olfactory transduction in rodent ORNs. We show that odorants rapidly and transiently activate PI3K in the olfactory cilia and in the olfactory epithelium in vitro. We implicate known G-protein–coupled isoforms of PI3K and show that they modulate not only the magnitude but also the onset kinetics of the electrophysiological response of ORNs to complex odorants. Finally, we show that the ability of a single odorant to inhibit another can be PI3K dependent. Our collective results provide compelling support for the idea that PI3K-dependent signaling mediates inhibitory odorant input to mammalian ORNs and at least in part contributes to the mixture suppression typically seen in the response of ORNs to complex natural odorants.

scholarly journals Classes and Narrowing Selectivity of Olfactory Receptor Neurons of Xenopus laevis Tadpoles

2004 ◽  
Vol 123 (2) ◽  
pp. 99-107 ◽  
Author(s):  
Ivan Manzini ◽  
Detlev Schild
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Xenopus Laevis ◽  
Olfactory Receptor ◽  
Developmental Stages ◽  
Olfactory Receptors ◽  
Response Spectra ◽  
Olfactory Receptor Neurons ◽  
Receptor Neurons ◽  
Response Profiles

In olfactory receptor neurons (ORNs) of aquatic animals amino acids have been shown to be potent stimuli. Here we report on calcium imaging experiments in slices of the olfactory mucosa of Xenopus laevis tadpoles. We were able to determine the response profiles of 283 ORNs to 19 amino acids, where one profile comprises the responses of one ORN to 19 amino acids. 204 out of the 283 response profiles differed from each other. 36 response spectra occurred more than once, i.e., there were 36 classes of ORNs identically responding to the 19 amino acids. The number of ORNs that formed a class ranged from 2 to 13. Shape and duration of amino acid-elicited [Ca2+]i transients showed a high degree of similarity upon repeated stimulation with the same amino acid. Different amino acids, however, in some cases led to clearly distinguishable calcium responses in individual ORNs. Furthermore, ORNs clearly appeared to gain selectivity over time, i.e., ORNs of later developmental stages responded to less amino acids than ORNs of earlier stages. We discuss the narrowing of ORN selectivity over stages in the context of expression of olfactory receptors.

Odor-Stimulated Phosphatidylinositol 3-Kinase in Lobster Olfactory Receptor Cells

2001 ◽  
Vol 85 (6) ◽  
pp. 2537-2544 ◽  
Author(s):  
Asylbek B. Zhainazarov ◽  
Richard Doolin ◽  
John-David Herlihy ◽  
Barry W. Ache
Keyword(s):  
Olfactory Receptor ◽  
Receptor Potential ◽  
Phosphatidylinositol 3 Kinase ◽  
Open Probability ◽  
Olfactory Transduction ◽  
C Terminus ◽  
Gated Channel ◽  
Receptor Neurons ◽  
Phosphoinositide Pathway

Two antagonists of phosphoinositide 3-OH kinases (PI3Ks), LY294002 and Wortmannin, reduced the magnitude of the receptor potential in lobster olfactory receptor neurons (ORNs) recorded by patch clamping the cells in vivo. An antibody directed against the c-terminus of human PI3K-P110β detected a molecule of predicted size in the outer dendrites of the ORNs. Two 3-phosphoinositides, PI(3,4)P2 (1–4 μM) and PI(3,4,5)P3 (1–4 μM) applied to the cytoplasmic side of inside-out patches taken from cultured lobster ORNs, reversibly activated a Na+-gated channel previously implicated in the transduction cascade in these cells. 3-Phosphoinositides were the most effective phosphoinositide (1 μM) in enhancing the open probability of the channel. Collectively, these results implicate 3-phosphoinositides in lobster olfactory transduction and raise the need to consider the 3-phosphoinositide pathway in olfactory transduction.

scholarly journals Heterotrimeric kinesin-II is necessary and sufficient to promote different stepwise assembly of morphologically distinct bipartite cilia in Drosophila antenna

2011 ◽  
Vol 22 (6) ◽  
pp. 769-781 ◽  
Author(s):  
Swadhin C. Jana ◽  
Mukul Girotra ◽  
Krishanu Ray
Keyword(s):  
Olfactory Receptor ◽  
Primary Cilia ◽  
Olfactory Receptors ◽  
Type I ◽  
Sensory Cilia ◽  
Receptor Neurons ◽  
Olfactory Receptor Genes ◽  
Necessary And Sufficient ◽  
Stepwise Assembly ◽  
Mechanical Sensing

Structurally diverse sensory cilia have evolved from primary cilia, a microtubule-based cellular extension engaged in chemical and mechanical sensing and signal integration. The diversity is often associated with functional specialization. The olfactory receptor neurons in Drosophila, for example, express three distinct bipartite cilia displaying different sets of olfactory receptors on them. Molecular description underlying their assembly and diversification is still incomplete. Here, we show that the branched and the slender olfactory cilia develop in two distinct step-wise patterns through the pupal stages before the expression of olfactory receptor genes in olfactory neurons. The process initiates with a thin procilium growth from the dendrite apex, followed by volume increment in successive stages. Mutations in the kinesin-II subunit genes either eliminate or restrict the cilia growth as well as tubulin entry into the developing cilia. Together with previous results, our results here suggest that heterotrimeric kinesin-II is the primary motor engaged in all type-I sensory cilia assembly in Drosophila and that the cilia structure diversity is achieved through additional transports supported by the motor during development.

scholarly journals An ammonium transporter is a non-canonical olfactory receptor for ammonia

2021 ◽  
Author(s):  
Alina Vulpe ◽  
Hyong S. Kim ◽  
Sydney Ballou ◽  
Shiuan-Tze Wu ◽  
Veit Grabe ◽  
...  
Keyword(s):  
Olfactory Receptor ◽  
Ectopic Expression ◽  
Behavioral Responses ◽  
Olfactory Receptors ◽  
Ammonium Transporter ◽  
Disease Vectors ◽  
Agricultural Pests ◽  
Neuron Populations ◽  
Transporter Family ◽  
New Type

SummaryTwo families of ligand-gated ion channels function as olfactory receptors in insects. Here, we show that these canonical olfactory receptors are not necessary for responses to ammonia, a key ecological odor that is attractive to many insects including disease vectors and agricultural pests. Instead, we show that a member of the ancient electrogenic ammonium transporter family, Amt, is a new type of olfactory receptor. We report two hitherto unidentified olfactory neuron populations that mediate neuronal and behavioral responses to ammonia. Their endogenous ammonia responses are Amt-dependent, and ectopic expression of either Drosophila or Anopheles Amt confers ammonia sensitivity. Amt is the first transporter known to function as an olfactory receptor in animals, and its role may be conserved across insect species.

scholarly journals Single-cell transcriptomes of developing and adult olfactory receptor neurons in Drosophila

2020 ◽  
Author(s):  
Colleen N. McLaughlin ◽  
Maria Brbić ◽  
Qijing Xie ◽  
Tongchao Li ◽  
Felix Horns ◽  
...  
Keyword(s):  
Single Cell ◽  
Olfactory Receptor ◽  
Developmental Stages ◽  
Sensory Modality ◽  
Antennal Segment ◽  
Olfactory Receptors ◽  
Olfactory Receptor Neurons ◽  
Receptor Neurons ◽  
Sensory Responses ◽  
And Function

AbstractRecognition of environmental cues is essential for the survival of all organisms. Precise transcriptional changes occur to enable the generation and function of the neural circuits underlying sensory perception. To gain insight into these changes, we generated single-cell transcriptomes of Drosophila olfactory receptor neurons (ORNs), thermosensory and hygrosensory neurons from the third antennal segment at an early developmental and adult stage. We discovered that ORNs maintain expression of the same olfactory receptors across development. Using these receptors and computational approaches, we matched transcriptomic clusters corresponding to anatomically and physiologically defined neuronal types across multiple developmental stages. Cell-type-specific transcriptomes, in part, reflected axon trajectory choices in early development and sensory modality in adults. Our analysis also uncovered type-specific and broadly expressed genes that could modulate adult sensory responses. Collectively, our data reveal important transcriptomic features of sensory neuron biology and provides a resource for future studies of their development and physiology.

scholarly journals Coordinating Receptor Expression and Wiring Specificity in Olfactory Receptor Neurons

2019 ◽  
Author(s):  
Hongjie Li ◽  
Tongchao Li ◽  
Felix Horns ◽  
Jiefu Li ◽  
Qijing Xie ◽  
...  
Keyword(s):  
Olfactory Receptor ◽  
Olfactory Receptors ◽  
Receptor Expression ◽  
Olfactory Receptor Neurons ◽  
Unique Combination ◽  
Axon Targeting ◽  
Transcriptional Regulatory ◽  
Receptor Neurons ◽  
Transcriptional Regulatory Mechanisms ◽  
The Brain

The ultimate function of a neuron is determined by both its physiology and connectivity, but the transcriptional regulatory mechanisms that coordinate these two features are not well understood1–4. The Drosophila Olfactory receptor neurons (ORNs) provide an excellent system to investigate this question. As in mammals5, each Drosophila ORN class is defined by the expression of a single olfactory receptor or a unique combination thereof, which determines their odor responses, and by the single glomerulus to which their axons target, which determines how sensory signals are represented in the brain6–10. In mammals, the coordination of olfactory receptor expression and wiring specificity is accomplished in part by olfactory receptors themselves regulating ORN wiring specificity11–13. However, Drosophila olfactory receptors do not instruct axon targeting6, 14, raising the question as to how receptor expression and wiring specificity are coordinated. Using single-cell RNA-sequencing and genetic analysis, we identified 33 transcriptomic clusters for fly ORNs. We unambiguously mapped 17 to glomerular classes, demonstrating that transcriptomic clusters correspond well with anatomically and physiologically defined ORN classes. We found that each ORN expresses ~150 transcription factors (TFs), and identified a master TF that regulates both olfactory receptor expression and wiring specificity. A second TF plays distinct roles, regulating only receptor expression in one class and only wiring in another. Thus, fly ORNs utilize diverse transcriptional strategies to coordinate physiology and connectivity.

Expression of mRNAs Encoding for Two Different Olfactory Receptors in a Subset of Olfactory Receptor Neurons

2001 ◽  
Vol 75 (1) ◽  
pp. 185-195 ◽  
Author(s):  
Nancy E. Rawson ◽  
Jim Eberwine ◽  
Ryan Dotson ◽  
Jennifer Jackson ◽  
Patricia Ulrich ◽  
...  
Keyword(s):  
Olfactory Receptor ◽  
Olfactory Receptors ◽  
Olfactory Receptor Neurons ◽  
Receptor Neurons

scholarly journals Opposing effects of bone morphogenetic proteins on neuron production and survival in the olfactory receptor neuron lineage

Development ◽  
2000 ◽  
Vol 127 (24) ◽  
pp. 5403-5413 ◽  
Author(s):  
J. Shou ◽  
R.C. Murray ◽  
P.C. Rim ◽  
A.L. Calof
Keyword(s):  
Bone Morphogenetic Proteins ◽  
Olfactory Receptor ◽  
Stromal Cell ◽  
Olfactory Receptor Neuron ◽  
Negative Effects ◽  
Low Concentrations ◽  
Binding Factor ◽  
Progenitor Cell Proliferation ◽  
Receptor Neurons ◽  
Opposing Effects

In olfactory epithelium (OE) cultures, bone morphogenetic proteins (BMPs) can strongly inhibit neurogenesis. Here we provide evidence that BMPs also promote, and indeed are required, for OE neurogenesis. Addition of the BMP antagonist noggin inhibited neurogenesis in OE-stromal cell co-cultures. Bmp2, Bmp4 and Bmp7 were expressed by OE stroma, and low concentrations of BMP4 (below the threshold for inhibition of neurogenesis) stimulated neurogenesis; BMP7 did not exhibit a stimulatory effect at any concentration tested. Stromal cell conditioned medium also stimulated neurogenesis; part of this effect was due to the presence within it of a noggin-binding factor or factors. Studies of the pro-neurogenic effect of BMP4 indicated that it did not increase progenitor cell proliferation, but rather promoted survival of newly generated olfactory receptor neurons. These findings indicate that BMPs exert both positive and negative effects on neurogenesis, depending on ligand identity, ligand concentration and the particular cell in the lineage that is responding. In addition, they reveal the presence of a factor or factors, produced by OE stroma, that can synergize with BMP4 to stimulate OE neurogenesis.

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