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Hawkins SJ, Gärtner Y, Offner T, Weiss L, Maiello G, Hassenklöver T, Manzini I. The olfactory network of larval Xenopus laevis regenerates accurately after olfactory nerve transection. Eur J Neurosci 2024. [PMID: 38758670 DOI: 10.1111/ejn.16375] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2023] [Revised: 04/10/2024] [Accepted: 04/14/2024] [Indexed: 05/19/2024]
Abstract
Across vertebrate species, the olfactory epithelium (OE) exhibits the uncommon feature of lifelong neuronal turnover. Epithelial stem cells give rise to new neurons that can adequately replace dying olfactory receptor neurons (ORNs) during developmental and adult phases and after lesions. To relay olfactory information from the environment to the brain, the axons of the renewed ORNs must reconnect with the olfactory bulb (OB). In Xenopus laevis larvae, we have previously shown that this process occurs between 3 and 7 weeks after olfactory nerve (ON) transection. In the present study, we show that after 7 weeks of recovery from ON transection, two functionally and spatially distinct glomerular clusters are reformed in the OB, akin to those found in non-transected larvae. We also show that the same odourant response tuning profiles observed in the OB of non-transected larvae are again present after 7 weeks of recovery. Next, we show that characteristic odour-guided behaviour disappears after ON transection but recovers after 7-9 weeks of recovery. Together, our findings demonstrate that the olfactory system of larval X. laevis regenerates with high accuracy after ON transection, leading to the recovery of odour-guided behaviour.
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Affiliation(s)
- Sara J Hawkins
- Institute of Animal Physiology, Department of Animal Physiology and Molecular Biomedicine, Justus Liebig University Gießen, Gießen, Germany
- School of Biological Sciences, Faculty of Environmental and Life Sciences, University of Southampton, Southampton, UK
| | - Yvonne Gärtner
- Institute of Animal Physiology, Department of Animal Physiology and Molecular Biomedicine, Justus Liebig University Gießen, Gießen, Germany
- School of Biological Sciences, Faculty of Environmental and Life Sciences, University of Southampton, Southampton, UK
- Department of Neurology, Focus Program Translational Neuroscience (FTN) and Immunotherapy (FZI), Rhine-Main Neuroscience Network (rmn2), University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Thomas Offner
- Institute of Animal Physiology, Department of Animal Physiology and Molecular Biomedicine, Justus Liebig University Gießen, Gießen, Germany
| | - Lukas Weiss
- Institute of Animal Physiology, Department of Animal Physiology and Molecular Biomedicine, Justus Liebig University Gießen, Gießen, Germany
| | - Guido Maiello
- Department of Experimental Psychology, Justus Liebig University Gießen, Gießen, Germany
- School of Psychology, Faculty of Environmental and Life Sciences, University of Southampton, Southampton, UK
| | - Thomas Hassenklöver
- Institute of Animal Physiology, Department of Animal Physiology and Molecular Biomedicine, Justus Liebig University Gießen, Gießen, Germany
| | - Ivan Manzini
- Institute of Animal Physiology, Department of Animal Physiology and Molecular Biomedicine, Justus Liebig University Gießen, Gießen, Germany
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Weiss L, Segoviano Arias P, Offner T, Hawkins SJ, Hassenklöver T, Manzini I. Distinct interhemispheric connectivity at the level of the olfactory bulb emerges during Xenopus laevis metamorphosis. Cell Tissue Res 2021; 386:491-511. [PMID: 34580751 PMCID: PMC8595194 DOI: 10.1007/s00441-021-03527-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Accepted: 09/15/2021] [Indexed: 11/28/2022]
Abstract
During metamorphosis, the olfactory system of anuran tadpoles undergoes substantial restructuring. The main olfactory epithelium in the principal nasal cavity of Xenopus laevis tadpoles is associated with aquatic olfaction and transformed into the adult air-nose, while a new adult water-nose emerges in the middle cavity. Impacts of this metamorphic remodeling on odor processing, behavior, and network structure are still unexplored. Here, we used neuronal tracings, calcium imaging, and behavioral experiments to examine the functional connectivity between the epithelium and the main olfactory bulb during metamorphosis. In tadpoles, olfactory receptor neurons in the principal cavity project axons to glomeruli in the ventral main olfactory bulb. These projections are gradually replaced by receptor neuron axons from the newly forming middle cavity epithelium. Despite this reorganization in the ventral bulb, two spatially segregated odor processing streams remain undisrupted and behavioral responses to waterborne odorants are unchanged. Contemporaneously, new receptor neurons in the remodeling principal cavity innervate the emerging dorsal part of the bulb, which displays distinct wiring features. Glomeruli around its midline are innervated from the left and right nasal epithelia. Additionally, postsynaptic projection neurons in the dorsal bulb predominantly connect to multiple glomeruli, while half of projection neurons in the ventral bulb are uni-glomerular. Our results show that the “water system” remains functional despite metamorphic reconstruction. The network differences between the dorsal and ventral olfactory bulb imply a higher degree of odor integration in the dorsal main olfactory bulb. This is possibly connected with the processing of different odorants, airborne vs. waterborne.
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Affiliation(s)
- Lukas Weiss
- Institute of Animal Physiology, Department of Animal Physiology and Molecular Biomedicine, Justus-Liebig-University Giessen, 35392, Giessen, Germany.
| | - Paola Segoviano Arias
- Institute of Animal Physiology, Department of Animal Physiology and Molecular Biomedicine, Justus-Liebig-University Giessen, 35392, Giessen, Germany.,Max Planck Research Unit for Neurogenetics, 60438, Frankfurt, Germany
| | - Thomas Offner
- Institute of Animal Physiology, Department of Animal Physiology and Molecular Biomedicine, Justus-Liebig-University Giessen, 35392, Giessen, Germany
| | - Sara Joy Hawkins
- Institute of Animal Physiology, Department of Animal Physiology and Molecular Biomedicine, Justus-Liebig-University Giessen, 35392, Giessen, Germany
| | - Thomas Hassenklöver
- Institute of Animal Physiology, Department of Animal Physiology and Molecular Biomedicine, Justus-Liebig-University Giessen, 35392, Giessen, Germany
| | - Ivan Manzini
- Institute of Animal Physiology, Department of Animal Physiology and Molecular Biomedicine, Justus-Liebig-University Giessen, 35392, Giessen, Germany
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Terni B, Llobet A. Axon terminals control endolysosome diffusion to support synaptic remodelling. Life Sci Alliance 2021; 4:4/8/e202101105. [PMID: 34226200 PMCID: PMC8321675 DOI: 10.26508/lsa.202101105] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Revised: 06/14/2021] [Accepted: 06/15/2021] [Indexed: 11/27/2022] Open
Abstract
Endolysosomes present in the presynaptic terminal move by diffusion constrained by F-actin and increase their mobility during the remodelling of synaptic connectivity to support a local degradative activity. Endolysosomes are acidic organelles formed by the fusion of endosomes with lysosomes. In the presynaptic compartment they contribute to protein homeostasis, the maintenance of vesicle pools and synaptic stability. Here, we evaluated the mobility of endolysosomes found in axon terminals of olfactory sensory neurons of Xenopus tropicalis tadpoles. F-actin restricts the motion of these presynaptic acidic organelles which is characterized by a diffusion coefficient of 6.7 × 10−3 μm2·s−1. Local injection of secreted protein acidic and rich in cysteine (SPARC) in the glomerular layer of the olfactory bulb disrupts the structure of synaptic F-actin patches and increases the presence and mobility of endolysosomal organelles found in axon terminals. The increased motion of endolysosomes is localized to the presynaptic compartment and does not promote their access to axonal regions for retrograde transportation to the cell body. Local activation of synaptic degradation mechanisms mediated by SPARC coincides with a loss of the ability of tadpoles to detect waterborne odorants. Together, these observations show that the diffusion of presynaptic endolysosomes increases during conditions of synaptic remodelling to support their local degradative activity.
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Affiliation(s)
- Beatrice Terni
- Department of Pathology and Experimental Therapy, School of Medicine, Institute of Neurosciences, University of Barcelona, Barcelona, Spain .,Laboratory of Neurobiology, Bellvitge Biomedical Research Institute (IDIBELL), Barcelona, Spain
| | - Artur Llobet
- Department of Pathology and Experimental Therapy, School of Medicine, Institute of Neurosciences, University of Barcelona, Barcelona, Spain .,Laboratory of Neurobiology, Bellvitge Biomedical Research Institute (IDIBELL), Barcelona, Spain
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Weiss L, Manzini I, Hassenklöver T. Olfaction across the water-air interface in anuran amphibians. Cell Tissue Res 2021; 383:301-325. [PMID: 33496878 PMCID: PMC7873119 DOI: 10.1007/s00441-020-03377-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Accepted: 12/03/2020] [Indexed: 12/13/2022]
Abstract
Extant anuran amphibians originate from an evolutionary intersection eventually leading to fully terrestrial tetrapods. In many ways, they have to deal with exposure to both terrestrial and aquatic environments: (i) phylogenetically, as derivatives of the first tetrapod group that conquered the terrestrial environment in evolution; (ii) ontogenetically, with a development that includes aquatic and terrestrial stages connected via metamorphic remodeling; and (iii) individually, with common changes in habitat during the life cycle. Our knowledge about the structural organization and function of the amphibian olfactory system and its relevance still lags behind findings on mammals. It is a formidable challenge to reveal underlying general principles of circuity-related, cellular, and molecular properties that are beneficial for an optimized sense of smell in water and air. Recent findings in structural organization coupled with behavioral observations could help to understand the importance of the sense of smell in this evolutionarily important animal group. We describe the structure of the peripheral olfactory organ, the olfactory bulb, and higher olfactory centers on a tissue, cellular, and molecular levels. Differences and similarities between the olfactory systems of anurans and other vertebrates are reviewed. Special emphasis lies on adaptations that are connected to the distinct demands of olfaction in water and air environment. These particular adaptations are discussed in light of evolutionary trends, ontogenetic development, and ecological demands.
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Affiliation(s)
- Lukas Weiss
- Institute of Animal Physiology, Department of Animal Physiology and Molecular Biomedicine, Justus-Liebig-University Giessen, Heinrich-Buff-Ring 38, 35392, Giessen, Germany
| | - Ivan Manzini
- Institute of Animal Physiology, Department of Animal Physiology and Molecular Biomedicine, Justus-Liebig-University Giessen, Heinrich-Buff-Ring 38, 35392, Giessen, Germany
| | - Thomas Hassenklöver
- Institute of Animal Physiology, Department of Animal Physiology and Molecular Biomedicine, Justus-Liebig-University Giessen, Heinrich-Buff-Ring 38, 35392, Giessen, Germany.
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Hawkins SJ, Weiss L, Offner T, Dittrich K, Hassenklöver T, Manzini I. Functional Reintegration of Sensory Neurons and Transitional Dendritic Reduction of Mitral/Tufted Cells during Injury-Induced Recovery of the Larval Xenopus Olfactory Circuit. Front Cell Neurosci 2017; 11:380. [PMID: 29234276 PMCID: PMC5712363 DOI: 10.3389/fncel.2017.00380] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2017] [Accepted: 11/13/2017] [Indexed: 01/08/2023] Open
Abstract
Understanding the mechanisms involved in maintaining lifelong neurogenesis has a clear biological and clinical interest. In the present study, we performed olfactory nerve transection on larval Xenopus to induce severe damage to the olfactory circuitry. We surveyed the timing of the degeneration, subsequent rewiring and functional regeneration of the olfactory system following injury. A range of structural labeling techniques and functional calcium imaging were performed on both tissue slices and whole brain preparations. Cell death of olfactory receptor neurons and proliferation of stem cells in the olfactory epithelium were immediately increased following lesion. New olfactory receptor neurons repopulated the olfactory epithelium and once again showed functional responses to natural odorants within 1 week after transection. Reinnervation of the olfactory bulb (OB) by newly formed olfactory receptor neuron axons also began at this time. Additionally, we observed a temporary increase in cell death in the OB and a subsequent loss in OB volume. Mitral/tufted cells, the second order neurons of the olfactory system, largely survived, but transiently lost dendritic tuft complexity. The first odorant-induced responses in the OB were observed 3 weeks after nerve transection and the olfactory network showed signs of major recovery, both structurally and functionally, after 7 weeks.
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Affiliation(s)
- Sara J Hawkins
- Institute of Neurophysiology and Cellular Biophysics, University of Göttingen, Göttingen, Germany.,Institute of Animal Physiology, Department of Animal Physiology and Molecular Biomedicine, Justus Liebig University Giessen, Giessen, Germany
| | - Lukas Weiss
- Institute of Neurophysiology and Cellular Biophysics, University of Göttingen, Göttingen, Germany.,Institute of Animal Physiology, Department of Animal Physiology and Molecular Biomedicine, Justus Liebig University Giessen, Giessen, Germany
| | - Thomas Offner
- Institute of Neurophysiology and Cellular Biophysics, University of Göttingen, Göttingen, Germany.,Center for Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB), Göttingen, Germany
| | - Katarina Dittrich
- Institute of Neurophysiology and Cellular Biophysics, University of Göttingen, Göttingen, Germany.,Institute of Animal Physiology, Department of Animal Physiology and Molecular Biomedicine, Justus Liebig University Giessen, Giessen, Germany
| | - Thomas Hassenklöver
- Institute of Neurophysiology and Cellular Biophysics, University of Göttingen, Göttingen, Germany.,Institute of Animal Physiology, Department of Animal Physiology and Molecular Biomedicine, Justus Liebig University Giessen, Giessen, Germany.,Center for Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB), Göttingen, Germany
| | - Ivan Manzini
- Institute of Neurophysiology and Cellular Biophysics, University of Göttingen, Göttingen, Germany.,Institute of Animal Physiology, Department of Animal Physiology and Molecular Biomedicine, Justus Liebig University Giessen, Giessen, Germany.,Center for Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB), Göttingen, Germany
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