Automated quantification of vomeronasal glomeruli number, size, and color composition after immunofluorescent staining

Glomeruli are neuropil rich regions of the main or accessory olfactory bulbs where the axons of olfactory or vomeronasal neurons and dendrites of mitral/tufted cells form synaptic connections. In the main olfactory system olfactory sensory neurons (OSNs) expressing the same receptor innervate one or two glomeruli. However, in the accessory olfactory system, vomeronasal sensory neurons (VSNs) expressing the same receptor can innervate up to 30 different glomeruli in the accessory olfactory bulb (AOB). Genetic mutation disrupting genes with a role in defining the identity/diversity of olfactory and vomeronasal neurons can alter number and size of glomeruli. Interestingly, two cell surface molecules, Kirrel2 and Kirrel3, have been indicated to play a critical role in the organization of axons into glomeruli in the AOB. Being able to quantify differences in glomeruli features such as number, size or immunoreactivity for specific markers is an important experimental approach to validate the role of specific genes in controlling neuronal connectivity and circuit formation in control or mutant animals. Since the manual recognition and quantification of glomeruli on digital images is a challenging and time-consuming task, we generated a program in Python able to identify glomeruli in digital images and quantify their properties, such as size, number, and pixel intensity. Validation of our program indicates that our script is a fast and suitable tool for high throughput quantification of glomerular features of mouse lines with different genetic makeup.

Download Full-text

Automated quantification of vomeronasal glomeruli number, size, and color composition after immunofluorescent staining

Chemical Senses ◽

10.1093/chemse/bjab039 ◽

2021 ◽

Author(s):

Shahab Bahreini Jangjoo ◽

Jennifer M Lin ◽

Farhood Etaati ◽

Sydney Fearnley ◽

Jean-François Cloutier ◽

...

Keyword(s):

Sensory Neurons ◽

Olfactory System ◽

Digital Images ◽

Critical Role ◽

Genetic Mutation ◽

Immunofluorescent Staining ◽

Pixel Intensity ◽

Main Olfactory System ◽

Circuit Formation ◽

Accessory Olfactory System

Abstract Glomeruli are neuropil rich regions of the main or accessory olfactory bulbs where the axons of olfactory or vomeronasal neurons and dendrites of mitral/tufted cells form synaptic connections. In the main olfactory system olfactory sensory neurons (OSNs) expressing the same receptor innervate one or two glomeruli. However, in the accessory olfactory system, vomeronasal sensory neurons (VSNs) expressing the same receptor can innervate up to 30 different glomeruli in the accessory olfactory bulb (AOB). Genetic mutation disrupting genes with a role in defining the identity/diversity of olfactory and vomeronasal neurons can alter the number and size of glomeruli. Interestingly, two cell surface molecules, Kirrel2 and Kirrel3, have been indicated as playing a critical role in the organization of axons into glomeruli in the AOB. Being able to quantify differences in glomeruli features, such as number, size or immunoreactivity for specific markers, is an important experimental approach to validate the role of specific genes in controlling neuronal connectivity and circuit formation in either control or mutant animals. Since the manual recognition and quantification of glomeruli on digital images is a challenging and time-consuming task, we generated a program in Python able to identify glomeruli in digital images and quantify their properties, such as size, number, and pixel intensity. Validation of our program indicates that our script is a fast and suitable tool for high throughput quantification of glomerular features of mouse lines with different genetic makeup.

Download Full-text

Smad4 signaling establishes the somatosensory map of basal vomeronasal sensory neurons

10.1101/738393 ◽

2019 ◽

Author(s):

Ankana S. Naik ◽

Jennifer M. Lin ◽

Ed Zandro M. Taroc ◽

Raghu R. Katreddi ◽

Jesus A. Frias ◽

...

Keyword(s):

Sensory Neurons ◽

Critical Role ◽

Vomeronasal Organ ◽

Bmp Signaling ◽

Loss Of Function ◽

Neuronal Populations ◽

Innervation Patterns ◽

Circuit Formation ◽

Accessory Olfactory System ◽

Vomeronasal Sensory Neurons

SummaryThe accessory olfactory system is a unique model that can give insights on how the neurons can establish and maintain their identity, and connectivity. The vomeronasal organ (VNO) contains two distinct populations of vomeronasal sensory neurons (VSNs) each with specific innervation patterns to the accessory olfactory bulb (AOB). Though morphogenic signals are critical in defining various neuronal populations, the morphogenic signaling profiles that influence each VSN population remains unknown. Here, we found a pronounced BMP signaling gradient within the basal VSNs. By generating Smad4 conditional mutants, we disrupted canonical TGF-β/BMP signaling in maturing basal VSNs and in all mature VSNs. We show that Smad4 loss-of-function in immature basal neurons leads to a progressive loss of basal VSNs, reduced activation of the remnant basal VSNs, and aberrant glomeruli formation in posterior AOB. However, Smad4 ablation in all mature VSNs does not affect neuronal activity nor survival but causes aberrant glomeruli formation only in the posterior AOB. Our study reveals that Smad4 signaling plays a critical role in mediating development, function, and circuit formation of basal VSNs.

Download Full-text

Critical Role of GFR 1 in the Development and Function of the Main Olfactory System

Journal of Neuroscience ◽

10.1523/jneurosci.1522-12.2012 ◽

2012 ◽

Vol 32 (48) ◽

pp. 17306-17320 ◽

Cited By ~ 15

Author(s):

C. Marks ◽

L. Belluscio ◽

C. F. Ibanez

Keyword(s):

Olfactory System ◽

Critical Role ◽

And Function ◽

Main Olfactory System

Download Full-text

Physiology-forward identification of bile acid–sensitive vomeronasal receptors

Science Advances ◽

10.1126/sciadv.aaz6868 ◽

2020 ◽

Vol 6 (22) ◽

pp. eaaz6868

Author(s):

Wen Mai Wong ◽

Jie Cao ◽

Xingjian Zhang ◽

Wayne I. Doyle ◽

Luis L. Mercado ◽

...

Keyword(s):

Sensory Neurons ◽

Reproductive Behavior ◽

Olfactory System ◽

Cell Capture ◽

Biological Mechanisms ◽

New Approach ◽

Vomeronasal Receptors ◽

Receptor Interactions ◽

Specific Receptors ◽

Accessory Olfactory System

The mouse accessory olfactory system (AOS) supports social and reproductive behavior through the sensation of environmental chemosignals. A growing number of excreted steroids have been shown to be potent AOS cues, including bile acids (BAs) found in feces. As is still the case with most AOS ligands, the specific receptors used by vomeronasal sensory neurons (VSNs) to detect BAs remain unknown. To identify VSN BA receptors, we first performed a deep analysis of VSN BA tuning using volumetric GCaMP6f/s Ca2+ imaging. These experiments revealed multiple populations of BA-receptive VSNs with submicromolar sensitivities. We then developed a new physiology-forward approach for identifying AOS ligand-receptor interactions, which we call Fluorescence Live Imaging for Cell Capture and RNA sequencing, or FLICCR-seq. FLICCR-seq analysis revealed five specific V1R family receptors enriched in BA-sensitive VSNs. These studies introduce a powerful new approach for ligand-receptor matching and reveal biological mechanisms underlying mammalian BA chemosensation.

Download Full-text

Physiology-forward identification of bile acid sensitive vomeronasal receptors

10.1101/766592 ◽

2019 ◽

Cited By ~ 1

Author(s):

Wen Mai Wong ◽

Jie Cao ◽

Xingjian Zhang ◽

Wayne I. Doyle ◽

Luis L. Mercado ◽

...

Keyword(s):

Bile Acid ◽

Sensory Neurons ◽

Reproductive Behavior ◽

Olfactory System ◽

Biological Mechanisms ◽

New Approach ◽

Vomeronasal Receptors ◽

Receptor Interactions ◽

Specific Receptors ◽

Accessory Olfactory System

Abstract/SummaryThe mouse accessory olfactory system (AOS) supports social and reproductive behavior through the sensation of environmental chemosignals. A growing number of excreted steroids have been shown to be potent AOS cues, including bile acids (BAs) found in feces. As is still the case with most AOS ligands, the specific receptors used by vomeronasal sensory neurons (VSNs) to detect BAs remain unknown. To identify VSN BA receptors, we first performed a deep analysis of VSN BA tuning using volumetric GCaMP6f/s Ca2+ imaging. These experiments revealed both broadly and narrowly tuned populations of BA-receptive VSNs with sub-micromolar sensitivities. We then developed a new physiology-forward approach for identifying AOS ligand-receptor interactions, which we call Fluorescence Live Imaging for Cell Capture and RNA-seq, or FLICCR-seq. FLICCR-seq analysis revealed 5 specific V1R-family receptors enriched in BA-sensitive VSNs. These studies introduce a powerful new approach for ligand-receptor matching and reveal biological mechanisms underlying mammalian BA chemosensation.

Download Full-text

Aldehyde-specific responses of olfactory sensory neurons in the praying mantis

Scientific Reports ◽

10.1038/s41598-021-81359-5 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Kota Ezaki ◽

Takashi Yamashita ◽

Thomas Carle ◽

Hidehiro Watanabe ◽

Fumio Yokohari ◽

...

Keyword(s):

Sensory Neurons ◽

Activity Patterns ◽

Critical Role ◽

Response Spectra ◽

Olfactory Cues ◽

Olfactory Sensory Neurons ◽

Praying Mantis ◽

Pheromonal Communication ◽

Class B ◽

Excitatory Responses

AbstractAlthough praying mantises rely mainly on vision for predatory behaviours, olfaction also plays a critical role in feeding and mating behaviours. However, the receptive processes underlying olfactory signals remain unclear. Here, we identified olfactory sensory neurons (OSNs) that are highly tuned to detect aldehydes in the mantis Tenodera aridifolia. In extracellular recordings from OSNs in basiconic sensilla on the antennae, we observed three different spike shapes, indicating that at least three OSNs are housed in a single basiconic sensillum. Unexpectedly, one of the three OSNs exhibited strong excitatory responses to a set of aldehydes. Based on the similarities of the response spectra to 15 different aldehydes, the aldehyde-specific OSNs were classified into three classes: B, S, and M. Class B broadly responded to most aldehydes used as stimulants; class S responded to short-chain aldehydes (C3–C7); and class M responded to middle-length chain aldehydes (C6–C9). Thus, aldehyde molecules can be finely discriminated based on the activity patterns of a population of OSNs. Because many insects emit aldehydes for pheromonal communication, mantises might use aldehydes as olfactory cues for locating prey habitat.

Download Full-text

Odor response adaptation in Drosophila—a continuous individualization process

Cell and Tissue Research ◽

10.1007/s00441-020-03384-6 ◽

2021 ◽

Vol 383 (1) ◽

pp. 143-148

Author(s):

Shadi Jafari ◽

Mattias Alenius

Keyword(s):

Sensory Neurons ◽

Olfactory System ◽

Multiple Time Scales ◽

Multiple Time ◽

Olfactory Perception ◽

Adaptation Mechanisms ◽

Metabolic States ◽

The Central Nervous System ◽

Olfactory Adaptation ◽

Central Adaptation

AbstractOlfactory perception is very individualized in humans and also in Drosophila. The process that individualize olfaction is adaptation that across multiple time scales and mechanisms shape perception and olfactory-guided behaviors. Olfactory adaptation occurs both in the central nervous system and in the periphery. Central adaptation occurs at the level of the circuits that process olfactory inputs from the periphery where it can integrate inputs from other senses, metabolic states, and stress. We will here focus on the periphery and how the fast, slow, and persistent (lifelong) adaptation mechanisms in the olfactory sensory neurons individualize the Drosophila olfactory system.

Download Full-text

Region-specific amyloid-β accumulation in the olfactory system influences olfactory sensory neuronal dysfunction in 5xFAD mice

Alzheimer s Research & Therapy ◽

10.1186/s13195-020-00730-2 ◽

2021 ◽

Vol 13 (1) ◽

Author(s):

Gowoon Son ◽

Seung-Jun Yoo ◽

Shinwoo Kang ◽

Ameer Rasheed ◽

Da Hae Jung ◽

...

Keyword(s):

Olfactory Bulb ◽

Sensory Neurons ◽

Olfactory System ◽

Amyloid Β ◽

Olfactory Sensory Neurons ◽

Basal Cells ◽

Irreversible Damage ◽

5Xfad Mouse ◽

Peripheral Areas ◽

5Xfad Mice

Abstract Background Hyposmia in Alzheimer’s disease (AD) is a typical early symptom according to numerous previous clinical studies. Although amyloid-β (Aβ), which is one of the toxic factors upregulated early in AD, has been identified in many studies, even in the peripheral areas of the olfactory system, the pathology involving olfactory sensory neurons (OSNs) remains poorly understood. Methods Here, we focused on peripheral olfactory sensory neurons (OSNs) and delved deeper into the direct relationship between pathophysiological and behavioral results using odorants. We also confirmed histologically the pathological changes in 3-month-old 5xFAD mouse models, which recapitulates AD pathology. We introduced a numeric scale histologically to compare physiological phenomenon and local tissue lesions regardless of the anatomical plane. Results We observed the odorant group that the 5xFAD mice showed reduced responses to odorants. These also did not physiologically activate OSNs that propagate their axons to the ventral olfactory bulb. Interestingly, the amount of accumulated amyloid-β (Aβ) was high in the OSNs located in the olfactory epithelial ectoturbinate and the ventral olfactory bulb glomeruli. We also observed irreversible damage to the ectoturbinate of the olfactory epithelium by measuring the impaired neuronal turnover ratio from the basal cells to the matured OSNs. Conclusions Our results showed that partial and asymmetrical accumulation of Aβ coincided with physiologically and structurally damaged areas in the peripheral olfactory system, which evoked hyporeactivity to some odorants. Taken together, partial olfactory dysfunction closely associated with peripheral OSN’s loss could be a leading cause of AD-related hyposmia, a characteristic of early AD.

Download Full-text