1
|
Lazzari M, Bettini S, Milani L, Maurizii MG, Franceschini V. Response of Olfactory Sensory Neurons to Mercury Ions in Zebrafish: An Immunohistochemical Study. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2022; 28:227-242. [PMID: 35177137 DOI: 10.1017/s1431927621013763] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Olfactory sensory neurons (OSNs) of fish belong to three main types: ciliated olfactory sensory neurons (cOSNs), microvillous olfactory sensory neurons (mOSNs), and crypt cells. Mercury is a toxic metal harmful for olfaction. We exposed the olfactory epithelium of zebrafish to three sublethal Hg2+ concentrations. Molecular markers specific for the different types of OSNs were immunohistochemically detected. Image analysis of treated sections enabled counting of marked cells and measurement of staining optical density indicative of the response of OSNs to Hg2+ exposure. The three types of OSNs reacted to mercury in a different way. Image analysis revealed that mOSNs are more susceptible to Hg2+ exposure than cOSNs and crypt cell density decreases. Moreover, while the ratio between sensory/nonsensory epithelium areas is unchanged, epithelium thickness drops, and dividing cells increase in the basal layer of the olfactory epithelium. Cell death but also reduction of apical processes and marker expression could account for changes in OSN immunostaining. Also, the differential results between dorsal and ventral halves of the olfactory rosette could derive from different water flows inside the olfactory chamber or different subpopulations in OSNs.
Collapse
Affiliation(s)
- Maurizio Lazzari
- Department of Biological, Geological and Environmental Sciences, University of Bologna, Bologna40126, Italy
| | - Simone Bettini
- Department of Biological, Geological and Environmental Sciences, University of Bologna, Bologna40126, Italy
| | - Liliana Milani
- Department of Biological, Geological and Environmental Sciences, University of Bologna, Bologna40126, Italy
| | - Maria G Maurizii
- Department of Biological, Geological and Environmental Sciences, University of Bologna, Bologna40126, Italy
| | - Valeria Franceschini
- Department of Biological, Geological and Environmental Sciences, University of Bologna, Bologna40126, Italy
| |
Collapse
|
2
|
Camilieri-Asch V, Caddy HT, Hubbard A, Rigby P, Doyle B, Shaw JA, Mehnert A, Partridge JC, Yopak KE, Collin SP. Multimodal Imaging and Analysis of the Neuroanatomical Organization of the Primary Olfactory Inputs in the Brownbanded Bamboo Shark, Chiloscyllium punctatum. Front Neuroanat 2020; 14:560534. [PMID: 33324175 PMCID: PMC7726474 DOI: 10.3389/fnana.2020.560534] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2020] [Accepted: 09/23/2020] [Indexed: 11/22/2022] Open
Abstract
There is currently a limited understanding of the morphological and functional organization of the olfactory system in cartilaginous fishes, particularly when compared to bony fishes and terrestrial vertebrates. In this fish group, there is a clear paucity of information on the characterization, density, and distribution of olfactory receptor neurons (ORNs) within the sensory olfactory epithelium lining the paired olfactory rosettes, and their functional implications with respect to the hydrodynamics of incurrent water flow into the nares. This imaging study examines the brownbanded bamboo shark Chiloscyllium punctatum (Elasmobranchii) and combines immunohistochemical labeling using antisera raised against five G-protein α-subunits (Gαs/olf, Gαq/11/14, Gαi–1/2/3, Gαi–3, Gαo) with light and electron microscopy, to characterize the morphological ORN types present. Three main ORNs (“long”, “microvillous” and “crypt-like”) are confirmed and up to three additional microvilli-bearing types are also described; “Kappe-like” (potential or homologous “Kappe” as in teleosts), “pear-shaped” and “teardrop-shaped” cells. These morphotypes will need to be confirmed molecularly in the future. Using X-ray diffusible iodine-based contrast-enhanced computed tomography (diceCT), high-resolution scans of the olfactory rosettes, olfactory bulbs (OBs), peduncles, and telencephalon reveal a lateral segregation of primary olfactory inputs within the OBs, with distinct medial and lateral clusters of glomeruli, suggesting a potential somatotopic organization. However, most ORN morphotypes are found to be ubiquitously distributed within the medial and lateral regions of the olfactory rosette, with at least three microvilli-bearing ORNs labeled with anti-Gαo found in significantly higher densities in lateral lamellae [in lateral lamellae] and on the anterior portion of lamellae (facing the olfactory cavity). These microvilli-bearing ORN morphotypes (microvillous, “Kappe-like,” “pear-shaped,” and “teardrop-shaped”) are the most abundant across the olfactory rosette of this species, while ciliated ORNs are less common and crypt cells are rare. Spatial simulations of the fluid dynamics of the incurrent water flow into the nares and within the olfactory cavities indicate that the high densities of microvilli-bearing ORNs located within the lateral region of the rosette are important for sampling incoming odorants during swimming and may determine subsequent tracking behavior.
Collapse
Affiliation(s)
- Victoria Camilieri-Asch
- School of Biological Sciences, The University of Western Australia, Perth, WA, Australia.,The Neuroecology Group, UWA Oceans Institute, The University of Western Australia, Perth, WA, Australia
| | - Harrison T Caddy
- Vascular Engineering Laboratory, Centre for Medical Research, Harry Perkins Institute of Medical Research, The University of Western Australia, Perth, WA, Australia.,School of Engineering, The University of Western Australia, Perth, WA, Australia
| | - Alysia Hubbard
- Centre for Microscopy, Characterisation and Analysis, The University of Western Australia, Perth, WA, Australia
| | - Paul Rigby
- Centre for Microscopy, Characterisation and Analysis, The University of Western Australia, Perth, WA, Australia
| | - Barry Doyle
- Vascular Engineering Laboratory, Centre for Medical Research, Harry Perkins Institute of Medical Research, The University of Western Australia, Perth, WA, Australia.,School of Engineering, The University of Western Australia, Perth, WA, Australia.,Australian Research Council Centre for Personalised Therapeutics Technologies, Perth, WA, Australia.,BHF Centre for Cardiovascular Science, The University of Edinburgh, Edinburgh, United Kingdom
| | - Jeremy A Shaw
- Centre for Microscopy, Characterisation and Analysis, The University of Western Australia, Perth, WA, Australia
| | - Andrew Mehnert
- Centre for Microscopy, Characterisation and Analysis, The University of Western Australia, Perth, WA, Australia.,National Imaging Facility, Brisbane, QLD, Australia
| | - Julian C Partridge
- The Neuroecology Group, UWA Oceans Institute, The University of Western Australia, Perth, WA, Australia
| | - Kara E Yopak
- Department of Biology and Marine Biology, Center for Marine Science, University of North Carolina Wilmington, Wilmington, NC, United States
| | - Shaun P Collin
- The Neuroecology Group, UWA Oceans Institute, The University of Western Australia, Perth, WA, Australia.,School of Life Sciences, La Trobe University, Melbourne, VIC, Australia
| |
Collapse
|
3
|
Dymek J, Rosenqwist G, Kuciel M, Lauriano ER, Capillo G, Zaccone G, Żuwała K. Micro‐ and macro‐morphology of the olfactory organ of
Syngnathus typhle
(Syngnathidae, Actinopterygii). ACTA ZOOL-STOCKHOLM 2020. [DOI: 10.1111/azo.12328] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Affiliation(s)
- Jakub Dymek
- Department of Comparative Anatomy Faculty of Biology Institute of Zoology and Biomedical Research Jagiellonian University Cracow Poland
| | - Gunilla Rosenqwist
- Department of Earth Sciences, Natural Resources and Sustainable Development Uppsala University Uppsala Sweden
| | - Michał Kuciel
- Department of Toxicology and Environmental Disease Faculty of Medicine Poison Information Centre Jagiellonian University Cracow Poland
| | - Eugenia Rita Lauriano
- Department of Chemical Biological, Pharmaceutical, and Environmental Sciences University of Messina Messina Italy
| | - Gioele Capillo
- Department of Veterinary Sciences University of Messina Messina Italy
| | - Giacomo Zaccone
- Department of Biomedical and Dental Sciences and Morphofunctional Imaging University of Messina Messina Italy
| | - Krystyna Żuwała
- Department of Comparative Anatomy Faculty of Biology Institute of Zoology and Biomedical Research Jagiellonian University Cracow Poland
| |
Collapse
|
4
|
Lazzari M, Bettini S, Milani L, Maurizii MG, Franceschini V. Differential nickel-induced responses of olfactory sensory neuron populations in zebrafish. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2019; 206:14-23. [PMID: 30415017 DOI: 10.1016/j.aquatox.2018.10.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Revised: 10/15/2018] [Accepted: 10/19/2018] [Indexed: 06/09/2023]
Abstract
The olfactory epithelium of fish includes three main types of olfactory sensory neurons (OSNs). Whereas ciliated (cOSNs) and microvillous olfactory sensory neurons (mOSNs) are common to all vertebrates, a third, smaller group, the crypt cells, is exclusive for fish. Dissolved pollutants reach OSNs, thus resulting in impairment of the olfactory function with possible neurobehavioral damages, and nickel represents a diffuse olfactory toxicant. We studied the effects of three sublethal Ni2+ concentrations on the different OSN populations of zebrafish that is a widely used biological model. We applied image analysis with cell count and quantification of histochemically-detected markers of the different types of OSNs. The present study shows clear evidence of a differential responses of OSN populations to treatments. Densitometric values for Gα olf, a marker of cOSNs, decreased compared to control and showed a concentration-dependent effect in the ventral half of the olfactory rosette. The densitometric analysis of TRPC2, a marker of mOSNs, revealed a statistically significant reduction compared to control, smaller than the decrease for Gα olf and without concentration-dependent effects. After exposure, olfactory epithelium stained with anti-calretinin, a marker of c- and mOSNs, revealed a decrease in thickness while the sensory area appeared unchanged. The thickness reduction together with increased densitometric values for HuC/D, a marker of mature and immature neurons, suggests that the decrements in Gα olf and TRPC2 immunostaining may depend on cell death. However, reductions in the number of apical processes and of antigen expression could be a further explanation. We hypothesize that cOSNs are more sensitive than mOSNs to Ni2+ exposure. Difference between subpopulations of OSNs or differences in water flux throughout the olfactory cavity could account for the greater susceptibility of the OSNs located in the ventral half of the olfactory rosette. Cell count of anti-TrkA immunopositive cells reveals that Ni2+ exposure does not affect crypt cells. The results of this immunohistochemical study are not in line with those obtained by electro-olfactogram.
Collapse
Affiliation(s)
- Maurizio Lazzari
- Department of Biological, Geological and Environmental Sciences, University of Bologna, 40126 Bologna, Italy.
| | - Simone Bettini
- Department of Biological, Geological and Environmental Sciences, University of Bologna, 40126 Bologna, Italy
| | - Liliana Milani
- Department of Biological, Geological and Environmental Sciences, University of Bologna, 40126 Bologna, Italy
| | - Maria Gabriella Maurizii
- Department of Biological, Geological and Environmental Sciences, University of Bologna, 40126 Bologna, Italy
| | - Valeria Franceschini
- Department of Biological, Geological and Environmental Sciences, University of Bologna, 40126 Bologna, Italy
| |
Collapse
|
5
|
Stengel D, Wahby S, Braunbeck T. In search of a comprehensible set of endpoints for the routine monitoring of neurotoxicity in vertebrates: sensory perception and nerve transmission in zebrafish (Danio rerio) embryos. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2018; 25:4066-4084. [PMID: 29022183 DOI: 10.1007/s11356-017-0399-y] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2017] [Accepted: 10/02/2017] [Indexed: 05/20/2023]
Abstract
In order to develop a test battery based on a variety of neurological systems in fish, three sensory systems (vision, olfaction, and lateral line) as well as nerve transmission (acetylcholine esterase) were analyzed in zebrafish (Danio rerio) embryos with respect to their suitability as a model for the screening of neurotoxic trace substances in aquatic ecosystems. As a selection of known or putative neurotoxic compounds, amidotrizoic acid, caffeine, cypermethrin, dichlorvos, 2,4-dinitrotoluene, 2,4-dichlorophenol, 4-nonylphenol, perfluorooctanoic acid, and perfluorooctane sulfonic acid were tested in the fish embryo test (OECD test guideline 236) to determine EC10 values, which were then used as maximum test concentration in subsequent neurotoxicity tests. Whereas inhibition of acetylcholinesterase was investigated biochemically both in vivo and in vitro (ex vivo), the sensory organs were studied in vivo by means of fluorescence microscopy and histopathology in 72- or 96-h-old zebrafish embryos, which are not regarded as protected developmental stages in Europe and thus - at least de jure - represent alternative test methods. Various steps of optimization allowed this neurotoxicity battery to identify neurotoxic potentials for five out of the nine compounds: Cypermethrin and dichlorvos could be shown to specifically modulate acetylcholinesterase activity; dichlorvos, 2,4-dichlorophenol, 4-nonylphenol, and perfluorooctane sulfonic acid led to a degeneration of neuromasts, whereas both vision and olfaction proved quite resistant to concentrations ≤ EC10 of all of the model neurotoxicants tested. Comparison of neurotoxic effects on acetylcholinesterase activity following in vivo and in vitro (ex vivo) exposure to cypermethrin provided hints to a specific enzyme-modulating activity of pyrethroid compounds. Enhancement of the neuromast assay by applying a simultaneous double-staining procedure and implementing a 4-scale scoring system (Stengel et al. 2017) led to reduced variability of results and better statistical resolution and allowed to differentiate location-dependent effects in single neuromasts. Since acetylcholinesterase inhibition and neuromast degeneration can be analyzed in 72- and 96-h-old zebrafish embryos exposed to neurotoxicants according to the standard protocol of the fish embryo toxicity test (OECD TG 236), the fish embryo toxicity test can be enhanced to serve as a sensitive neurotoxicity screening test in non-protected stages of vertebrates.
Collapse
Affiliation(s)
- Daniel Stengel
- Aquatic Ecology and Toxicology Group, Center for Organismal Studies (COS), University of Heidelberg, Im Neuenheimer Feld 120, 69120, Heidelberg, Germany
| | - Sarah Wahby
- Aquatic Ecology and Toxicology Group, Center for Organismal Studies (COS), University of Heidelberg, Im Neuenheimer Feld 120, 69120, Heidelberg, Germany
| | - Thomas Braunbeck
- Aquatic Ecology and Toxicology Group, Center for Organismal Studies (COS), University of Heidelberg, Im Neuenheimer Feld 120, 69120, Heidelberg, Germany.
| |
Collapse
|
6
|
Lauriano ER, Pergolizzi S, Gangemi J, Kuciel M, Capillo G, Aragona M, Faggio C. Immunohistochemical colocalization of G protein alpha subunits and 5-HT in the rectal gland of the cartilaginous fishScyliorhinus canicula. Microsc Res Tech 2017; 80:1018-1027. [DOI: 10.1002/jemt.22896] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Revised: 04/03/2017] [Accepted: 05/06/2017] [Indexed: 01/19/2023]
Affiliation(s)
- E. R. Lauriano
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences; University of Messina; Messina 98166 Italy
| | - S. Pergolizzi
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences; University of Messina; Messina 98166 Italy
| | - J. Gangemi
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences; University of Messina; Messina 98166 Italy
| | - M. Kuciel
- Department of Comparative Anatomy, Institute of Zoology; Jagiellonian University; Krakow 30-387 Poland
| | - G. Capillo
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences; University of Messina; Messina 98166 Italy
| | - M. Aragona
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences; University of Messina; Messina 98166 Italy
| | - C. Faggio
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences; University of Messina; Messina 98166 Italy
| |
Collapse
|
7
|
Lazzari M, Bettini S, Milani L, Maurizii MG, Franceschini V. Differential response of olfactory sensory neuron populations to copper ion exposure in zebrafish. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2017; 183:54-62. [PMID: 27992776 DOI: 10.1016/j.aquatox.2016.12.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2016] [Revised: 12/07/2016] [Accepted: 12/13/2016] [Indexed: 06/06/2023]
Abstract
The peripheral olfactory system of fish is in direct contact with the external aqueous environment, so dissolved contaminants can easily impair sensory functions and cause neurobehavioral injuries. The olfactory epithelium of fish is arranged in lamellae forming a rosette in the olfactory cavity and contains three main types of olfactory sensory neurons (OSNs): ciliated (cOSNs) and microvillous olfactory sensory neurons (mOSNs), common to all vertebrates, and a third minor group of olfactory neurons, crypt cells, absent in tetrapods. Since copper is a ubiquitously diffusing olfactory toxicant and a spreading contaminant in urban runoff, we investigated the effect of low copper concentration on the three different OSNs in the olfactory epithelium of zebrafish, a model system widely used in biological research. Image analysis was applied for morphometry and quantification of immunohistochemically detected OSNs. Copper exposure resulted in an evident decrease in olfactory epithelium thickness. Moreover, after exposure, the lamellae of the dorsal and ventral halves of the olfactory rosettes showed a different increase in their sensory areas, suggesting a lateral migration of new cells into non-sensory regions. The results of the present study provide clear evidence of a differential response of the three neural cell populations of zebrafish olfactory mucosa after 96h of exposure to copper ions at the sublethal concentration of 30μgL-1. Densitometric values of cONS, immunostained with anti-G αolf, decreased of about 60% compared to the control. When the fish were transferred to water without copper addition and examined after 3, 10 and 30days, we observed a partial restoration of anti-G αolf staining intensity to normal condition. The recovery of cOSNs appeared sustained by neuronal proliferation, quantified with anti-PCNA immunostaining, in particular in the early days after exposure. The densitometric analysis applied to mOSNs, immunostained with anti-TRPC2, revealed a statistically significant decrease of about 30% compared to the control. For cOSNs and mOSNs, the decrement in staining intensity may be indicative of cell death, but reduction in antigen expression may not be excluded. In the post-exposure period of 1 month we did not find recovery of mOSNs. We hypothesize that cOSNs are more sensitive than mOSNs to copper treatment, but also more prompted to tissue repair. Anti-TrkA-immunopositive crypt cells appeared not to be affected by copper exposure since statistical analysis excluded any significant difference between the control and treated fish. Comparative studies on OSNs would greatly enhance our understanding of the mechanisms of olfaction.
Collapse
Affiliation(s)
- Maurizio Lazzari
- Department of Biological, Geological and Environmental Sciences, University of Bologna, 40126 Bologna, Italy.
| | - Simone Bettini
- Department of Biological, Geological and Environmental Sciences, University of Bologna, 40126 Bologna, Italy
| | - Liliana Milani
- Department of Biological, Geological and Environmental Sciences, University of Bologna, 40126 Bologna, Italy
| | - Maria Gabriella Maurizii
- Department of Biological, Geological and Environmental Sciences, University of Bologna, 40126 Bologna, Italy
| | - Valeria Franceschini
- Department of Biological, Geological and Environmental Sciences, University of Bologna, 40126 Bologna, Italy
| |
Collapse
|
8
|
Ferrando S, Gallus L, Gambardella C, Marchesotti E, Ravera S, Franceschini V, Masini MA. Effects of urea on the molecules involved in the olfactory signal transduction: a preliminary study on Danio rerio. FISH PHYSIOLOGY AND BIOCHEMISTRY 2014; 40:1793-1800. [PMID: 25092237 DOI: 10.1007/s10695-014-9968-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2014] [Accepted: 07/24/2014] [Indexed: 06/03/2023]
Abstract
Among vertebrates, the physiologically uremic Chondrichthyes are the only class which are not presenting the ciliated olfactory receptor neurons in the olfactory neuroepithelium. The only sequenced genome for this class revealed only three olfactory receptor genes and the immunohistochemical detection of G protein alpha subunit typically coupled to the olfactory receptors (Gα(olf)) failed in different species. Chronic renal disease can represent a cause of olfactory impairment in human. In this context, our present study focused on investigating potential effects of high urea concentration on the olfactory epithelium of vertebrates. Larvae of the teleost fish Danio rerio were exposed to urea in order to assess the effects on the olfactory signal transduction; in particular on both the olfactory receptors and the Gα(olf). The endocytosis of neutral red dye in the olfactory mucosa was detected in control and urea-exposed larvae. The amount of neutral red dye uptake was used as a marker of binding and internalization of the Gα(olf). The neutral red dye endocytosis was not affected by urea exposure, hence suggesting that the presence of the Gα(olf) and their binding to the odorants are not affected by urea treatment, either. The presence and distribution of Gα(olf) were investigated in the olfactory epithelium of control and urea-exposed larvae, using a commercial antibody. The immunoreactivity was increased after urea treatment, suggesting an effect of urea on the expression or degradation of this G protein alpha subunit.
Collapse
Affiliation(s)
- Sara Ferrando
- DISTAV, University of Genoa, Viale Benedetto XV 5, 16132, Genoa, Italy,
| | | | | | | | | | | | | |
Collapse
|
9
|
Kappe neurons, a novel population of olfactory sensory neurons. Sci Rep 2014; 4:4037. [PMID: 24509431 PMCID: PMC3918911 DOI: 10.1038/srep04037] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2013] [Accepted: 01/13/2014] [Indexed: 11/28/2022] Open
Abstract
Perception of olfactory stimuli is mediated by distinct populations of olfactory sensory neurons, each with a characteristic set of morphological as well as functional parameters. Beyond two large populations of ciliated and microvillous neurons, a third population, crypt neurons, has been identified in teleost and cartilaginous fishes. We report here a novel, fourth olfactory sensory neuron population in zebrafish, which we named kappe neurons for their characteristic shape. Kappe neurons are identified by their Go-like immunoreactivity, and show a distinct spatial distribution within the olfactory epithelium, similar to, but significantly different from that of crypt neurons. Furthermore, kappe neurons project to a single identified target glomerulus within the olfactory bulb, mdg5 of the mediodorsal cluster, whereas crypt neurons are known to project exclusively to the mdg2 glomerulus. Kappe neurons are negative for established markers of ciliated, microvillous and crypt neurons, but appear to have microvilli. Kappe neurons constitute the fourth type of olfactory sensory neurons reported in teleost fishes and their existence suggests that encoding of olfactory stimuli may require a higher complexity than hitherto assumed already in the peripheral olfactory system.
Collapse
|
10
|
Graña P, Folgueira M, Huesa G, Anadón R, Yáñez J. Immunohistochemical distribution of calretinin and calbindin (D-28k) in the brain of the cladistian Polypterus senegalus. J Comp Neurol 2014; 521:2454-85. [PMID: 23296683 DOI: 10.1002/cne.23293] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2012] [Revised: 10/05/2012] [Accepted: 12/13/2012] [Indexed: 12/19/2022]
Abstract
Polypteriform fishes are believed to be basal to other living ray-finned bony fishes, and they may be useful for providing information of the neural organization that existed in the brain of the earliest ray-finned fishes. The calcium-binding proteins calretinin (CR) and calbindin-D28k (CB) have been widely used to characterize neuronal populations in vertebrate brains. Here, the distribution of the immunoreactivity against CR and CB was investigated in the olfactory organ and brain of Polypterus senegalus and compared to the distribution of these molecules in other ray-finned fishes. In general, CB-immunoreactive (ir) neurons were less abundant than CR-ir cells. CR immunohistochemistry revealed segregation of CR-ir olfactory receptor neurons in the olfactory mucosa and their bulbar projections. Our results confirmed important differences between pallial regions in terms of CR immunoreactivity of cell populations and afferent fibers. In the habenula, these calcium-binding proteins revealed right-left asymmetry of habenular subpopulations and segregation of their interpeduncular projections. CR immunohistochemistry distinguished among some thalamic, pretectal, and posterior tubercle-derived populations. Abundant CR-ir populations were observed in the midbrain, including the tectum. CR immunoreactivity was also useful for characterizing a putative secondary gustatory/visceral nucleus in the isthmus, and for distinguishing territories in the primary viscerosensory column and octavolateral region. Comparison of the data obtained within a segmental neuromeric context indicates that some CB-ir and CR-ir populations in polypteriform fishes are shared with other ray-finned fishes, but other positive structures appear to have evolved following the separation between polypterids and other ray-finned fishes.
Collapse
Affiliation(s)
- Patricia Graña
- Department of Cell and Molecular Biology, Faculty of Sciences, University of A Coruña, 15008-A Coruña, Spain
| | | | | | | | | |
Collapse
|