scholarly journals Flies Avoid Current Atmospheric CO2 Concentrations

2021 ◽  
Vol 12 ◽  
Author(s):  
Habibe K. Üçpunar ◽  
Ilona C. Grunwald Kadow
Keyword(s):  
18Th Century ◽  
Sensory System ◽  
Olfactory Receptors ◽  
Food Sources ◽  
Behavioral Experiments ◽  
Electrophysiological Recordings ◽  
Vinegar Fly ◽  
Key Odorants ◽  
Receptor Neurons ◽  
Atmospheric Co2 Concentrations

CO2 differs from most other odors by being ubiquitously present in the air animals inhale. CO2 levels of the atmosphere, however, are subject to change. Depending on the landscape, temperature, and time of the year, CO2 levels can change even on shortest time scales. In addition, since the 18th century the CO2 baseline keeps increasing due to the intensive fossil fuel usage. However, we do not know whether this change is significant for animals, and if yes whether and how animals adapt to this change. Most insects possess olfactory receptors to detect the gaseous molecule, and CO2 is one of the key odorants for insects such as the vinegar fly Drosophila melanogaster to find food sources and to warn con-specifics. So far, CO2 and its sensory system have been studied in the context of rotting fruit and other CO2-emitting sources to investigate flies’ response to significantly elevated levels of CO2. However, it has not been addressed whether flies detect and potentially react to atmospheric levels of CO2. By using behavioral experiments, here we show that flies can detect atmospheric CO2 concentrations and, if given the choice, prefer air with sub-atmospheric levels of the molecule. Blocking the synaptic release from CO2 receptor neurons abolishes this choice. Based on electrophysiological recordings, we hypothesize that CO2 receptors, similar to ambient temperature receptors, actively sample environmental CO2 concentrations close to atmospheric levels. Based on recent findings and our data, we hypothesize that Gr-dependent CO2 receptors do not primarily serve as a cue detector to find food sources or avoid danger, instead they function as sensors for preferred environmental conditions.

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.

Physiological Evidence for the Discrimination ofl-Arginine From Structural Analogues by the Zebrafish Olfactory System

1999 ◽  
Vol 82 (6) ◽  
pp. 3160-3167 ◽  
Author(s):  
D. L. Lipschitz ◽  
W. C. Michel
Keyword(s):  
Amino Acid ◽  
Olfactory System ◽  
Basic Amino Acid ◽  
Chain Structure ◽  
Sensory Epithelium ◽  
Amino Groups ◽  
Electrophysiological Recordings ◽  
Cross Adaptation ◽  
Receptor Neurons ◽  
Activity Dependent

Although it is generally assumed that fish are capable of discriminating amino acid odorants on the basis of differences in side-chain structure, less is known about their ability to discriminate amino acids with modifications to α-carboxyl and α-amino groups. In this study, the ability of the zebrafish olfactory system to detect and presumably discriminate analogues of the basic amino acid Arg was assessed, by using cross-adaptation and activity-dependent labeling techniques. Electrophysiological recordings established that esterification (l-arginine methyl ester; AME) or deletion (agmatine or amino-4-guanidobutane; AGB) of the α-carboxyl group yielded odorants more potent than Arg, whereas deletion of the α-amino group (l-argininic acid; AA) yielded a less potent analogue. In cross-adaptation experiments, no test-competitor odorant combination yielded complete cross-adaptation, suggesting the detection of these Arg analogues by multiple odorant receptors (ORs) with partially nonoverlapping specificities. Activity-dependent immunocytochemical labeling of olfactory receptor neurons supported this conclusion. AGB, an ion-channel–permeant probe (and odorant), labeled 4.9 ± 0.4% ( n = 24) of sensory epithelium, whereas the addition of Arg, 1-ethylguanidine sulfate, l-α-amino-β-guanidinopropionate, or AME to AGB resulted in a significant elevation of labeling (8–14%). This study provides evidence that the olfactory system has the potential to discriminate among amino acid odorants with modified α-carboxyl and α-amino groups.

Crustacean Visual Circuits Underlying Behavior

2019 ◽  
Author(s):  
Daniel Tomsic ◽  
Julieta Sztarker
Keyword(s):  
Visual Processing ◽  
Visual Information ◽  
General Structure ◽  
Visual Space ◽  
Experimental Manipulation ◽  
Visually Guided ◽  
Decapod Crustaceans ◽  
Behavioral Experiments ◽  
Electrophysiological Recordings ◽  
Visual Behaviors

Decapod crustaceans, in particular semiterrestrial crabs, are highly visual animals that greatly rely on visual information. Their responsiveness to visual moving stimuli, with behavioral displays that can be easily and reliably elicited in the laboratory, together with their sturdiness for experimental manipulation and the accessibility of their nervous system for intracellular electrophysiological recordings in the intact animal, make decapod crustaceans excellent experimental subjects for investigating the neurobiology of visually guided behaviors. Investigations of crustaceans have elucidated the general structure of their eyes and some of their specializations, the anatomical organization of the main brain areas involved in visual processing and their retinotopic mapping of visual space, and the morphology, physiology, and stimulus feature preferences of a number of well-identified classes of neurons, with emphasis on motion-sensitive elements. This anatomical and physiological knowledge, in connection with results of behavioral experiments in the laboratory and the field, are revealing the neural circuits and computations involved in important visual behaviors, as well as the substrate and mechanisms underlying visual memories in decapod crustaceans.

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 Olfactory and behavioural responses of the blood-sucking bug Triatoma infestans to odours of vertebrate hosts

2001 ◽  
Vol 204 (3) ◽  
pp. 585-597 ◽  
Author(s):  
P. Guerenstein ◽  
P. Guerin
Keyword(s):  
Olfactory Receptors ◽  
Isobutyric Acid ◽  
Triatoma Infestans ◽  
Behavioural Responses ◽  
Air Stream ◽  
Blood Sucking ◽  
Electrophysiological Recordings ◽  
Electrophysiological Responses ◽  
Vertebrate Hosts ◽  
High Firing

Olfactory receptors in basiconic and grooved-peg sensilla on the antenna of fifth-instar Triatoma infestans nymphs respond to host odours. Gas chromatography analyses of host odour extracts coupled to electrophysiological recordings from basiconic sensillum receptors indicate that nonanal is a constituent of sheep wool and chicken feather odour that stimulates one of the receptors in this type of sensillum. Similar analyses revealed isobutyric acid in rabbit odour to be a chemostimulant for one of the receptors in grooved-peg sensilla. The response of the aldehyde receptor was higher to heptanal, octanal and nonanal than to other aliphatic aldehydes, and the response of the acid receptor was higher to isobutyric acid than to other short-chain branched and unbranched acids. The behavioural responses of fifth-instar T. infestans nymphs to nonanal and isobutyric acid in an air-stream on a servosphere indicate that, whereas nonanal causes activation of the bugs, isobutyric acid induces an increase in upwind displacement, i.e. odour-conditioned anemotaxis. Binary mixtures of these compounds did not improve the attraction obtained with isobutyric acid alone. A comparison of the behavioural and electrophysiological responses of the bugs to different amounts of isobutyric acid in air suggests that attraction is obtained at concentrations that causes low-to-moderate increases in the firing rate of the acid-excited receptor in the grooved-peg sensilla, whereas at a dose that evokes relatively high firing rates (>40 Hz) no attraction is obtained.

Encoding of social signals in all three electrosensory pathways of Eigenmannia virescens

2014 ◽  
Vol 112 (9) ◽  
pp. 2076-2091 ◽  
Author(s):  
Anna Stöckl ◽  
Fabian Sinz ◽  
Jan Benda ◽  
Jan Grewe
Keyword(s):  
Weakly Electric Fish ◽  
Social Signals ◽  
Active System ◽  
Behavioral Experiments ◽  
Communication Signals ◽  
Parallel Pathways ◽  
Electrophysiological Recordings ◽  
Eigenmannia Virescens ◽  
Neuronal Representation

Extracting complementary features in parallel pathways is a widely used strategy for a robust representation of sensory signals. Weakly electric fish offer the rare opportunity to study complementary encoding of social signals in all of its electrosensory pathways. Electrosensory information is conveyed in three parallel pathways: two receptor types of the tuberous (active) system and one receptor type of the ampullary (passive) system. Modulations of the fish's own electric field are sensed by these receptors and used in navigation, prey detection, and communication. We studied the neuronal representation of electric communication signals (called chirps) in the ampullary and the two tuberous pathways of Eigenmannia virescens. We first characterized different kinds of chirps observed in behavioral experiments. Since Eigenmannia chirps simultaneously drive all three types of receptors, we studied their responses in in vivo electrophysiological recordings. Our results demonstrate that different electroreceptor types encode different aspects of the stimuli and each appears best suited to convey information about a certain chirp type. A decoding analysis of single neurons and small populations shows that this specialization leads to a complementary representation of information in the tuberous and ampullary receptors. This suggests that a potential readout mechanism should combine information provided by the parallel processing streams to improve chirp detectability.

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 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 Optogenetic olfactory behavior depends on illumination characteristics

2019 ◽  
Author(s):  
Tayfun Tumkaya ◽  
James Stewart ◽  
Safwan B. Burhanudin ◽  
Adam Claridge-Chang
Keyword(s):  
Neural Activity ◽  
Olfactory Receptor ◽  
Olfactory Receptor Neurons ◽  
Olfactory Behavior ◽  
Pulsed Light ◽  
Behavioral Experiments ◽  
Light Intensities ◽  
Light Stimuli ◽  
Receptor Neurons ◽  
Illumination Regime

AbstractOptogenetics has become an important tool for the study of behavior, enabling neuroscientists to infer causations by examining behavior after activating genetically circumscribed neurons with light. Light-induced neural activity is affected by illumination parameters used in experiments, such as intensity, duration, and frequency. Here, we hypothesized that the intensity of light and the presence of oscillations in illumination would alter optogenetically induced olfactory behaviours. To test this, we activated olfactory receptor neurons (ORNs) in Drosophila by using either static or pulsed light stimuli across a range of light intensities. The various regimes elicited distinct behavioral valence responses (attraction, aversion, indifference) from several ORN types. Our results demonstrate the importance of both frequency and intensity for interpreting optogenetic behavioral experiments accurately; successfully generalizing optogenetic results requires the use of more than a single illumination regime.

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.

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