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 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.

scholarly journals Organization and distribution of glomeruli in the bowhead whale olfactory bulb

2014 ◽  
Author(s):  
Takushi Kishida ◽  
J. G. M. Thewissen ◽  
Sharon Usip ◽  
John C George ◽  
Robert S Suydam
Keyword(s):  
Olfactory Bulb ◽  
Olfactory Receptor ◽  
Olfactory Receptors ◽  
Molecular Data ◽  
Dorsal Side ◽  
Bowhead Whale ◽  
Model Organisms ◽  
Marker Genes ◽  
Baleen Whales ◽  
Olfactory Receptor Genes

Although modern baleen whales still possess a functional olfactory systems that includes olfactory bulbs, cranial nerve I and olfactory receptor genes, their olfactory capabilities have been reduced profoundly. This is probably in response to their fully aquatic lifestyle. The glomeruli that occur in the olfactory bulb can be divided into two non-overlapping domains, a dorsal domain and a ventral domain. Recent molecular studies revealed that all modern whales have lost olfactory receptor genes and marker genes that are specific to the dorsal domain, and that a modern baleen whale possess only 60 olfactory receptor genes. Here we show that olfactory bulb of bowhead whales (Balaena mysticetus, Mysticeti) lacks glomeruli on the dorsal side, consistent with the molecular data. In addition, we estimate that there are more than 4,000 glomeruli in the bowhead whale olfactory bulb. Olfactory sensory neurons that express the same olfactory receptor in mice generally project to two specific glomeruli in an olfactory bulb, meaning that ratio of the number of olfactory receptors : the number of glomeruli is approximately 1:2. However, we show here that this ratio is not applicable to whales, indicating the limitation of mice as model organisms for understanding the initial coding of odor information among mammals.

Olfactory epithelia exhibit progressive functional and morphological defects in CF mice

2007 ◽  
Vol 293 (2) ◽  
pp. C574-C583 ◽  
Author(s):  
Barbara R. Grubb ◽  
Troy D. Rogers ◽  
Heather M. Kulaga ◽  
Kimberlie A. Burns ◽  
Robert L. Wonsetler ◽  
...  
Keyword(s):  
Olfactory Receptor ◽  
Ussing Chamber ◽  
Fold Increase ◽  
Olfactory Receptor Neurons ◽  
Sodium Absorption ◽  
Sustentacular Cells ◽  
Sensory Cilia ◽  
Morphological Defects ◽  
Receptor Neurons ◽  
Chamber Studies

In normal nasal epithelium, the olfactory receptor neurons (ORNs) are continuously replaced through the differentiation of progenitor cells. The olfactory epithelium (OE) of the cystic fibrosis (CF) mouse appears normal at birth, yet by 6 mo of age, a marked dysmorphology of sustentacular cells and a dramatic reduction in olfactory receptor neurons are evident. Electroolfactograms revealed that the odor-evoked response in 30-day-old CF mice was reduced ∼45%; in older CF mice, a ∼70% reduction was observed compared with the wild type (WT) response. Consistent with studies of CF airway epithelia, Ussing chamber studies of OE isolated from CF mice showed a lack of forskolin-stimulated Cl− secretion and an ∼12-fold increase in amiloride-sensitive sodium absorption compared with WT mice. We hypothesize that the marked hyperabsorption of Na+, most likely by olfactory sustentacular cells, leads to desiccation of the surface layer in which the sensory cilia reside, followed by degeneration of the ORNs. The CF mouse thus provides a novel model to examine the mechanisms of disease-associated loss of olfactory function.

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.

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.

scholarly journals Coevolution of the olfactory organ and its receptor repertoire in ray-finned fishes

2021 ◽  
Author(s):  
Maxime Policarpo ◽  
Katherine E Bemis ◽  
Patrick Laurenti ◽  
Laurent Legendre ◽  
Jean-Christophe Sandoz ◽  
...  
Keyword(s):  
Olfactory Receptor ◽  
Evolutionary Dynamics ◽  
Olfactory Receptors ◽  
Gene Families ◽  
Olfactory Organ ◽  
Functional Link ◽  
Receptor Repertoire ◽  
Mola Mola ◽  
Main Gene ◽  
Olfactory Receptor Genes

Ray-finned fishes (Actinopterygii) perceive their environment through a range of sensory modalities, including olfaction 1,2. Anatomical diversity of the olfactory organ suggests that olfaction is differentially important among species 1,3,4. To explore this topic, we studied the evolutionary dynamics of the four main gene families (OR, TAAR, ORA/VR1 and OlfC/VR2) 5 coding for olfactory receptors in 185 species of ray-finned fishes. The large variation in the number of functional genes, between 28 in the Ocean Sunfish Mola mola and 1317 in the Reedfish Erpetoichthys calabaricus, is the result of parallel expansions and contractions of the four main gene families. Several ancient and independent simplifications of the olfactory organ are associated with massive gene losses. In contrast, polypteriforms, which have a unique and complex olfactory organ, have almost twice as many olfactory receptor genes as any other ray-finned fish. These observations suggest a functional link between morphology of the olfactory organ and richness of the olfactory receptor repertoire. Further, our results demonstrate that the genomic underpinning of olfaction in ray-finned fishes is heterogeneous and presents a dynamic pattern of evolutionary expansions, simplifications and reacquisitions.

scholarly journals Revisiting olfactory receptors as putative drivers of cancer

2017 ◽  
Vol 2 ◽  
pp. 9 ◽  
Author(s):  
Marco Ranzani ◽  
Vivek Iyer ◽  
Ximena Ibarra-Soria ◽  
Martin Del Castillo Velasco-Herrera ◽  
Mathew Garnett ◽  
...  
Keyword(s):  
Signal Transduction ◽  
Cell Lines ◽  
Cancer Cell ◽  
Olfactory Receptor ◽  
Receptor Gene ◽  
Signal Transduction Pathway ◽  
Olfactory Receptors ◽  
Cancer Cell Lines ◽  
Specific Manner ◽  
Olfactory Receptor Genes

Background: Olfactory receptors (ORs) recognize odorant molecules and activate a signal transduction pathway that ultimately leads to the perception of smell. This process also modulates the apoptotic cycle of olfactory sensory neurons in an olfactory receptor-specific manner. Recent reports indicate that some olfactory receptors are expressed in tissues other than the olfactory epithelium suggesting that they may have pleiotropic roles. Methods: We investigated the expression of 301 olfactory receptor genes in a comprehensive panel of 968 cancer cell lines. Results: Forty-nine per cent of cell lines show expression of at least one olfactory receptor gene. Some receptors display a broad pattern of expression across tumour types, while others were expressed in cell lines from a particular tissue. Additionally, most of the cancer cell lines expressing olfactory receptors express the effectors necessary for OR-mediated signal transduction. Remarkably, among cancer cell lines, OR2C3 is exclusively expressed in melanoma lines. We also confirmed the expression of OR2C3 in human melanomas, but not in normal melanocytes. Conclusions: The pattern of OR2C3 expression is suggestive of a functional role in the development and/or progression of melanoma. Some olfactory receptors may contribute to tumorigenesis.

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