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Abstract
AbstractMushroom bodies are known from annelids and arthropods and were formerly assumed to argue for a close relationship of these two taxa. Since molecular phylogenies univocally show that both taxa belong to two different clades in the bilaterian tree, similarity must either result from convergent evolution or from transformation of an ancestral mushroom body. Any morphological differences in the ultrastructure and composition of mushroom bodies could thus indicate convergent evolution that results from similar functional constraints. We here study the ultrastructure of the mushroom bodies, the glomerular neuropil, glia-cells and the general anatomy of the nervous system in Sthenelais boa. The neuropil of the mushroom bodies is composed of densely packed, small diameter neurites that lack individual or clusterwise glia enwrapping. Neurites of other regions of the brain are much more prominent, are enwrapped by glia-cell processes and thus can be discriminated from the neuropil of the mushroom bodies. The same applies to the respective neuronal somata. The glomerular neuropil of insects and annelids is a region of higher synaptic activity that result in a spheroid appearance of these structures. However, while these structures are sharply delimited from the surrounding neuropil of the brain by glia enwrapping in insects, this is not the case in Sthenelais boa. Although superficially similar, there are anatomical differences in the arrangement of glia-cells in the mushroom bodies and the glomerular neuropil between insects and annelids. Hence, we suppose that the observed differences rather evolved convergently to solve similar functional constrains than by transforming an ancestral mushroom body design.
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Polanska MA, Kirchhoff T, Dircksen H, Hansson BS, Harzsch S. Functional morphology of the primary olfactory centers in the brain of the hermit crab Coenobita clypeatus (Anomala, Coenobitidae). Cell Tissue Res 2020; 380:449-467. [PMID: 32242250 PMCID: PMC7242284 DOI: 10.1007/s00441-020-03199-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Accepted: 03/03/2020] [Indexed: 11/07/2022]
Abstract
Terrestrial hermit crabs of the genus Coenobita display strong behavioral responses to volatile odors and are attracted by chemical cues of various potential food sources. Several aspects of their sense of aerial olfaction have been explored in recent years including behavioral aspects and structure of their peripheral and central olfactory pathway. Here, we use classical histological methods and immunohistochemistry against the neuropeptides orcokinin and allatostatin as well as synaptic proteins and serotonin to provide insights into the functional organization of their primary olfactory centers in the brain, the paired olfactory lobes. Our results show that orcokinin is present in the axons of olfactory sensory neurons, which target the olfactory lobe. Orcokinin is also present in a population of local olfactory interneurons, which may relay lateral inhibition across the array of olfactory glomeruli within the lobes. Extensive lateral connections of the glomeruli were also visualized using the histological silver impregnation method according to Holmes-Blest. This technique also revealed the structural organization of the output pathway of the olfactory system, the olfactory projection neurons, the axons of which target the lateral protocerebrum. Within the lobes, the course of their axons seems to be reorganized in an axon-sorting zone before they exit the system. Together with previous results, we combine our findings into a model on the functional organization of the olfactory system in these animals.
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Affiliation(s)
- Marta A Polanska
- Department of Animal Physiology, Institute of Zoology, Faculty of Biology, University of Warsaw, 1 Miecznikowa Street, 02-096, Warsaw, Poland
| | - Tina Kirchhoff
- Zoological Institute and Museum, Department of Cytology and Evolutionary Biology, University of Greifswald, Soldmannstrasse 23, 17498, Greifswald, Germany
| | - Heinrich Dircksen
- Department of Zoology, Stockholm University, Svante Arrhenius väg 18B, SE-10691, Stockholm, Sweden
| | - Bill S Hansson
- Max-Planck-Institute for Chemical Ecology, Department of Evolutionary Neuroethology, Hans-Knöll-Straße 8, 07745, Jena, Germany
| | - Steffen Harzsch
- Zoological Institute and Museum, Department of Cytology and Evolutionary Biology, University of Greifswald, Soldmannstrasse 23, 17498, Greifswald, Germany.
- Max-Planck-Institute for Chemical Ecology, Department of Evolutionary Neuroethology, Hans-Knöll-Straße 8, 07745, Jena, Germany.
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Yan H, Opachaloemphan C, Mancini G, Yang H, Gallitto M, Mlejnek J, Leibholz A, Haight K, Ghaninia M, Huo L, Perry M, Slone J, Zhou X, Traficante M, Penick CA, Dolezal K, Gokhale K, Stevens K, Fetter-Pruneda I, Bonasio R, Zwiebel LJ, Berger SL, Liebig J, Reinberg D, Desplan C. An Engineered orco Mutation Produces Aberrant Social Behavior and Defective Neural Development in Ants. Cell 2017; 170:736-747.e9. [PMID: 28802043 PMCID: PMC5587193 DOI: 10.1016/j.cell.2017.06.051] [Citation(s) in RCA: 135] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2017] [Revised: 05/25/2017] [Accepted: 06/30/2017] [Indexed: 02/01/2023]
Abstract
Ants exhibit cooperative behaviors and advanced forms of sociality that depend on pheromone-mediated communication. Odorant receptor neurons (ORNs) express specific odorant receptors (ORs) encoded by a dramatically expanded gene family in ants. In most eusocial insects, only the queen can transmit genetic information, restricting genetic studies. In contrast, workers in Harpegnathos saltator ants can be converted into gamergates (pseudoqueens) that can found entire colonies. This feature facilitated CRISPR-Cas9 generation of germline mutations in orco, the gene that encodes the obligate co-receptor of all ORs. orco mutations should significantly impact olfaction. We demonstrate striking functions of Orco in odorant perception, reproductive physiology, and social behavior plasticity. Surprisingly, unlike in other insects, loss of OR functionality also dramatically impairs development of the antennal lobe to which ORNs project. Therefore, the development of genetics in Harpegnathos establishes this ant species as a model organism to study the complexity of eusociality.
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Affiliation(s)
- Hua Yan
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY 10016, USA; Howard Hughes Medical Institute, New York University School of Medicine, New York, NY 10016, USA
| | - Comzit Opachaloemphan
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY 10016, USA
| | - Giacomo Mancini
- Department of Biology, New York University, New York, NY 10003, USA
| | - Huan Yang
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY 10016, USA
| | - Matthew Gallitto
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY 10016, USA
| | - Jakub Mlejnek
- Department of Biology, New York University, New York, NY 10003, USA
| | | | - Kevin Haight
- School of Life Sciences, Arizona State University, Tempe, AZ 85287, USA
| | - Majid Ghaninia
- School of Life Sciences, Arizona State University, Tempe, AZ 85287, USA
| | - Lucy Huo
- Department of Biology, New York University, New York, NY 10003, USA
| | - Michael Perry
- Department of Biology, New York University, New York, NY 10003, USA
| | - Jesse Slone
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37235, USA
| | - Xiaofan Zhou
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37235, USA
| | - Maria Traficante
- Department of Biology, New York University, New York, NY 10003, USA
| | - Clint A Penick
- School of Life Sciences, Arizona State University, Tempe, AZ 85287, USA
| | - Kelly Dolezal
- School of Life Sciences, Arizona State University, Tempe, AZ 85287, USA
| | - Kaustubh Gokhale
- School of Life Sciences, Arizona State University, Tempe, AZ 85287, USA
| | - Kelsey Stevens
- Department of Biology, New York University, New York, NY 10003, USA
| | - Ingrid Fetter-Pruneda
- Laboratory of Social Evolution and Behavior, The Rockefeller University, New York, NY 10065, USA
| | - Roberto Bonasio
- Penn Epigenetics Institute, Departments of Cell and Developmental Biology, Genetics, and Biology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Laurence J Zwiebel
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37235, USA
| | - Shelley L Berger
- Penn Epigenetics Institute, Departments of Cell and Developmental Biology, Genetics, and Biology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA.
| | - Jürgen Liebig
- School of Life Sciences, Arizona State University, Tempe, AZ 85287, USA.
| | - Danny Reinberg
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY 10016, USA; Howard Hughes Medical Institute, New York University School of Medicine, New York, NY 10016, USA.
| | - Claude Desplan
- Department of Biology, New York University, New York, NY 10003, USA.
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Roselino AC, Hrncir M, da Cruz Landim C, Giurfa M, Sandoz JC. Sexual dimorphism and phenotypic plasticity in the antennal lobe of a stingless bee,Melipona scutellaris. J Comp Neurol 2015; 523:1461-73. [DOI: 10.1002/cne.23744] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Revised: 12/03/2014] [Accepted: 01/09/2015] [Indexed: 01/12/2023]
Affiliation(s)
- Ana Carolina Roselino
- Departamento de Biologia, Instituto de Biociências de Rio Claro; Universidade Estadual Paulista Júlio de Mesquita Filho; Rio Claro São Paulo 13506-900 Brazil
- Faculté des Sciences d'Orsay; Université Paris-Sud; Orsay cedex 91405 France
- Evolution, Genomes, Behavior and Ecology Lab; CNRS, Université Paris-Sud, IRD (UMR 9191); Gif-sur-Yvette 91198 France
| | - Michael Hrncir
- Departamento de Ciências Animais; Universidade Federal Rural do Semi-Árido; Mossoró 59625-900 Brazil
| | - Carminda da Cruz Landim
- Departamento de Biologia, Instituto de Biociências de Rio Claro; Universidade Estadual Paulista Júlio de Mesquita Filho; Rio Claro São Paulo 13506-900 Brazil
| | - Martin Giurfa
- Centre National de la Recherche Scientifique (CNRS); Centre de Recherches sur la Cognition Animale; 31062 Toulouse cedex 9 France
- Université de Toulouse (UPS); Centre de Recherches sur la Cognition Animale; 31062 Toulouse cedex 9 France
| | - Jean-Christophe Sandoz
- Evolution, Genomes, Behavior and Ecology Lab; CNRS, Université Paris-Sud, IRD (UMR 9191); Gif-sur-Yvette 91198 France
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Clifford MR, Riffell JA. Mixture and odorant processing in the olfactory systems of insects: a comparative perspective. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2013; 199:911-28. [PMID: 23660810 DOI: 10.1007/s00359-013-0818-6] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2013] [Revised: 04/06/2013] [Accepted: 04/08/2013] [Indexed: 01/18/2023]
Abstract
Natural olfactory stimuli are often complex mixtures of volatiles, of which the identities and ratios of constituents are important for odor-mediated behaviors. Despite this importance, the mechanism by which the olfactory system processes this complex information remains an area of active study. In this review, we describe recent progress in how odorants and mixtures are processed in the brain of insects. We use a comparative approach toward contrasting olfactory coding and the behavioral efficacy of mixtures in different insect species, and organize these topics around four sections: (1) Examples of the behavioral efficacy of odor mixtures and the olfactory environment; (2) mixture processing in the periphery; (3) mixture coding in the antennal lobe; and (4) evolutionary implications and adaptations for olfactory processing. We also include pertinent background information about the processing of individual odorants and comparative differences in wiring and anatomy, as these topics have been richly investigated and inform the processing of mixtures in the insect olfactory system. Finally, we describe exciting studies that have begun to elucidate the role of the processing of complex olfactory information in evolution and speciation.
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Affiliation(s)
- Marie R Clifford
- Department of Biology, University of Washington, Seattle, WA, 98195, USA,
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Abstract
Neuroethology utilizes a wide range of multidisciplinary approaches to decipher neural correlates of natural behaviors associated with an animal's ecological niche. By placing emphasis on comparative analyses of adaptive and evolutionary trends across species, a neuroethological perspective is uniquely suited to uncovering general organizational and biological principles that shape the function and anatomy of the nervous system. In this review, we focus on the application of neuroethological principles in the study of insect olfaction and discuss how ecological environment and other selective pressures influence the development of insect olfactory neurobiology, not only informing our understanding of olfactory evolution but also providing broader insights into sensory processing.
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Affiliation(s)
- Bill S Hansson
- Department of Evolutionary Neuroethology, Max Planck Institute for Chemical Ecology, Hans Knoell Strasse 8, 07749 Jena, Germany.
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Mysore K, Flister S, Müller P, Rodrigues V, Reichert H. Brain development in the yellow fever mosquito Aedes aegypti: a comparative immunocytochemical analysis using cross-reacting antibodies from Drosophila melanogaster. Dev Genes Evol 2011; 221:281-96. [PMID: 21956584 DOI: 10.1007/s00427-011-0376-2] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2011] [Accepted: 09/14/2011] [Indexed: 12/23/2022]
Abstract
Considerable effort has been directed towards understanding the organization and function of peripheral and central nervous system of disease vector mosquitoes such as Aedes aegypti. To date, all of these investigations have been carried out on adults but none of the studies addressed the development of the nervous system during the larval and pupal stages in mosquitoes. Here, we first screen a set of 30 antibodies, which have been used to study brain development in Drosophila, and identify 13 of them cross-reacting and labeling epitopes in the developing brain of Aedes. We then use the identified antibodies in immunolabeling studies to characterize general neuroanatomical features of the developing brain and compare them with the well-studied model system, Drosophila melanogaster, in larval, pupal, and adult stages. Furthermore, we use immunolabeling to document the development of specific components of the Aedes brain, namely the optic lobes, the subesophageal neuropil, and serotonergic system of the subesophageal neuropil in more detail. Our study reveals prominent differences in the developing brain in the larval stage as compared to the pupal (and adult) stage of Aedes. The results also uncover interesting similarities and marked differences in brain development of Aedes as compared to Drosophila. Taken together, this investigation forms the basis for future cellular and molecular investigations of brain development in this important disease vector.
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Affiliation(s)
- Keshava Mysore
- Biozentrum, University of Basel, Klinglebergstrasse 50, CH-4056 Basel, Switzerland
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Friedrich M. Drosophila as a developmental paradigm of regressive brain evolution: proof of principle in the visual system. BRAIN, BEHAVIOR AND EVOLUTION 2011; 78:199-215. [PMID: 21893944 DOI: 10.1159/000329850] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2011] [Accepted: 05/23/2011] [Indexed: 11/19/2022]
Abstract
Evolutionary developmental biology focuses heavily on the constructive evolution of body plan components, but there are many instances such as parasitism, cave adaptation, or postembryonic growth rate optimization where evolutionary regression is of adaptive value. This is particularly true in the nervous system because of its massive energy costs. However, comparatively little effort has thus far been made to understand the evolutionary developmental trajectories of adaptive nervous system reduction. This review focuses on the organization and evolution of the Drosophila larval brain, which represents an exceptional example of miniaturization, most dramatically in the visual system. It is specifically discussed how the dependency of outer optic lobe development on retinal innervation can be assumed to have facilitated a first evolutionary phase of larval visual system reduction. Afferent input-contingent development of neu- ral compartments very likely plays a widespread role in adaptive brain evolution. Understanding the complete deconstruction of the larval optic neuropiles in Drosophila awaits expanded comparative analysis but has the promise to inform about further developmental trajectories and mechanisms underlying regressive evolution of the brain.
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Affiliation(s)
- Markus Friedrich
- Department of Biological Sciences, School of Medicine, Wayne State University, Detroit, MI 48202, USA. friedrichm @ wayne.edu
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Pereanu W, Kumar A, Jennett A, Reichert H, Hartenstein V. Development-based compartmentalization of the Drosophila central brain. J Comp Neurol 2010; 518:2996-3023. [PMID: 20533357 DOI: 10.1002/cne.22376] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The neuropile of the Drosophila brain is subdivided into anatomically discrete compartments. Compartments are rich in terminal neurite branching and synapses; they are the neuropile domains in which signal processing takes place. Compartment boundaries are defined by more or less dense layers of glial cells as well as long neurite fascicles. These fascicles are formed during the larval period, when the approximately 100 neuronal lineages that constitute the Drosophila central brain differentiate. Each lineage forms an axon tract with a characteristic trajectory in the neuropile; groups of spatially related tracts congregate into the brain fascicles that can be followed from the larva throughout metamorphosis into the adult stage. Here we provide a map of the adult brain compartments and the relevant fascicles defining compartmental boundaries. We have identified the neuronal lineages contributing to each fascicle, which allowed us to compare compartments of the larval and adult brain directly. Most adult compartments can be recognized already in the early larval brain, where they form a "protomap" of the later adult compartments. Our analysis highlights the morphogenetic changes shaping the Drosophila brain; the data will be important for studies that link early-acting genetic mechanisms to the adult neuronal structures and circuits controlled by these mechanisms.
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Affiliation(s)
- Wayne Pereanu
- Department of Molecular Cell and Developmental Biology, University of California Los Angeles, Los Angeles, California 90095, USA.
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Mysore K, Shyamala BV, Rodrigues V. Morphological and developmental analysis of peripheral antennal chemosensory sensilla and central olfactory glomeruli in worker castes of Camponotus compressus (Fabricius, 1787). ARTHROPOD STRUCTURE & DEVELOPMENT 2010; 39:310-321. [PMID: 20438861 DOI: 10.1016/j.asd.2010.04.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2009] [Revised: 04/04/2010] [Accepted: 04/25/2010] [Indexed: 05/29/2023]
Abstract
The antennal lobes of different castes of the ant species Camponotus compressus show a marked diversity in the organization of their olfactory glomeruli. Notably, there is a significant difference in the number and size of glomeruli between the reproductives and the workers and among the different worker castes. In this report, we investigate the notion that these caste-specific differences in glomerular number might be accounted for, at least in part, by the differences in numbers of olfactory sensilla that target the antennal lobe. For this, we examine the number of sensilla on the antennal flagella of all the individual castes of C. compressus. This analysis reveals a striking correlation between sensillar number and the number of antennal glomeruli in a given caste. As a first step in investigating the causal mechanisms that might give raise to this correlation, we carry out an initial characterization of olfactory system development in the minor workers of C. compressus. We analyze the temporal pattern of innervations of the developing antennal lobe by olfactory sensory neuron axons. We document the development of the olfactory glomeruli in the antennal lobe during this process, which occurs during early pupal stages. Our findings provide the basis for future manipulative developmental studies on the role of sensory afferent number in glomerular development of different castes within the same species.
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Affiliation(s)
- Keshava Mysore
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, India
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Huetteroth W, El Jundi B, El Jundi S, Schachtner J. 3D-Reconstructions and Virtual 4D-Visualization to Study Metamorphic Brain Development in the Sphinx Moth Manduca Sexta. Front Syst Neurosci 2010; 4:7. [PMID: 20339481 PMCID: PMC2845058 DOI: 10.3389/fnsys.2010.00007] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2009] [Accepted: 02/21/2010] [Indexed: 11/13/2022] Open
Abstract
DURING METAMORPHOSIS, THE TRANSITION FROM THE LARVA TO THE ADULT, THE INSECT BRAIN UNDERGOES CONSIDERABLE REMODELING: new neurons are integrated while larval neurons are remodeled or eliminated. One well acknowledged model to study metamorphic brain development is the sphinx moth Manduca sexta. To further understand mechanisms involved in the metamorphic transition of the brain we generated a 3D standard brain based on selected brain areas of adult females and 3D reconstructed the same areas during defined stages of pupal development. Selected brain areas include for example mushroom bodies, central complex, antennal- and optic lobes. With this approach we eventually want to quantify developmental changes in neuropilar architecture, but also quantify changes in the neuronal complement and monitor the development of selected neuronal populations. Furthermore, we used a modeling software (Cinema 4D) to create a virtual 4D brain, morphing through its developmental stages. Thus the didactical advantages of 3D visualization are expanded to better comprehend complex processes of neuropil formation and remodeling during development. To obtain datasets of the M. sexta brain areas, we stained whole brains with an antiserum against the synaptic vesicle protein synapsin. Such labeled brains were then scanned with a confocal laser scanning microscope and selected neuropils were reconstructed with the 3D software AMIRA 4.1.
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Affiliation(s)
- Wolf Huetteroth
- Department of Biology, Animal Physiology, Philipps-University Marburg Marburg, Germany
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Mysore K, Subramanian KA, Sarasij RC, Suresh A, Shyamala BV, VijayRaghavan K, Rodrigues V. Caste and sex specific olfactory glomerular organization and brain architecture in two sympatric ant species Camponotus sericeus and Camponotus compressus (Fabricius, 1798). ARTHROPOD STRUCTURE & DEVELOPMENT 2009; 38:485-497. [PMID: 19539048 DOI: 10.1016/j.asd.2009.06.001] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2008] [Revised: 05/31/2009] [Accepted: 06/08/2009] [Indexed: 05/27/2023]
Abstract
We use monoclonal antibodies against synaptic proteins and anterograde tracing with neurobiotin to describe the architecture of the antennal lobes in different castes of two ant species -Camponotus sericeus and Camponotus compressus. The reproductives and worker classes are readily categorized based on size and external morphology. The overall organization of brain neuropile is comparable between castes with differences only in the visual ganglia. Males have a larger fraction of neuropile occupied by the medulla and lobula than females. In the diurnal species, C. sericeus these regions are more highly represented, than in the nocturnal species C. compressus. The most striking differences are in the antennal lobe where males possess a macroglomerulus, which is about ten times larger in volume than the other glomeruli; such a specialization is absent in females. Minor workers possess a significantly larger number of glomeruli than the majors despite the smaller overall volume of the lobe. These caste-specific differences occur mainly within glomerular clusters that receive input from sensory neurons that project in tracts - T4 and T5 - within the antennal nerve. The comparative anatomy of different castes of ants provides an entry point into a future systematic analysis of how divergent brain architectures can arise within a single species.
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Affiliation(s)
- Keshava Mysore
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bellary Road, Bangalore 560 065, India
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Gibson NJ, Tolbert LP, Oland LA. Roles of specific membrane lipid domains in EGF receptor activation and cell adhesion molecule stabilization in a developing olfactory system. PLoS One 2009; 4:e7222. [PMID: 19787046 PMCID: PMC2746287 DOI: 10.1371/journal.pone.0007222] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2009] [Accepted: 09/06/2009] [Indexed: 11/18/2022] Open
Abstract
Background Reciprocal interactions between glial cells and olfactory receptor neurons (ORNs) cause ORN axons entering the brain to sort, to fasciculate into bundles destined for specific glomeruli, and to form stable protoglomeruli in the developing olfactory system of an experimentally advantageous animal species, the moth Manduca sexta. Epidermal growth factor receptors (EGFRs) and the cell adhesion molecules (IgCAMs) neuroglian and fasciclin II are known to be important players in these processes. Methodology/Principal Findings We report in situ and cell-culture studies that suggest a role for glycosphingolipid-rich membrane subdomains in neuron-glia interactions. Disruption of these subdomains by the use of methyl-β-cyclodextrin results in loss of EGFR activation, depletion of fasciclin II in ORN axons, and loss of neuroglian stabilization in the membrane. At the cellular level, disruption leads to aberrant ORN axon trajectories, small antennal lobes, abnormal arrays of olfactory glomerul, and loss of normal glial cell migration. Conclusions/Significance We propose that glycosphingolipid-rich membrane subdomains (possible membrane rafts or platforms) are essential for IgCAM-mediated EGFR activation and for anchoring of neuroglian to the cytoskeleton, both required for normal extension and sorting of ORN axons.
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Affiliation(s)
- Nicholas J Gibson
- Arizona Research Laboratories Division of Neurobiology, University of Arizona, Tucson, Arizona, United States of America.
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Lacalli TC. Serial EM analysis of a copepod larval nervous system: Naupliar eye, optic circuitry, and prospects for full CNS reconstruction. ARTHROPOD STRUCTURE & DEVELOPMENT 2009; 38:361-375. [PMID: 19376268 DOI: 10.1016/j.asd.2009.04.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2009] [Revised: 04/07/2009] [Accepted: 04/08/2009] [Indexed: 05/27/2023]
Abstract
The medial eye and optic center of the first nauplius of Dactylopusia (=Dactylopodia) tisboides, a harpacticoid copepod, were reconstructed from serial EM micrographs. Axons from the eye project to a set of matching cartridges defined by glial cells processes, and input is then processed in sequence through two synaptic fields. A single class of local relay neurons provides the main pathway between these, subject to modulatory input from a class of densely stained neurons with distinctive dense terminals. The importance of other outside sources of synaptic input to the second synaptic field indicates that the latter is a major site for integrating the optic input with signals originating elsewhere in the CNS. This accords with physiological data on the shadow response in barnacles, whose visual system is also derived from a naupliar eye. With a body length of ca. 80microns, copepod larvae like that of Dactylopusia are arguably among the smallest functional metazoans with a complex nervous system. Hence they are promising subjects for full reconstruction of neural circuitry at the EM level that could, in principle, reveal where key decision-making functions are localized.
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Groh C, Rössler W. Caste-specific postembryonic development of primary and secondary olfactory centers in the female honeybee brain. ARTHROPOD STRUCTURE & DEVELOPMENT 2008; 37:459-468. [PMID: 18621587 DOI: 10.1016/j.asd.2008.04.001] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2008] [Revised: 04/01/2008] [Accepted: 04/01/2008] [Indexed: 05/26/2023]
Abstract
Eusocial insects are characterized by division of labor among a sterile worker caste and a reproductive queen. In the honeybee both female castes are determined postembryonically by environmental factors, and queens develop substantially faster than workers. Since olfaction plays a crucial role in organizing honeybee behavior and social interactions, we compared the development of primary and secondary olfactory centers in the brain. Age-synchronized queen and worker pupae were raised in incubators at 34.5 degrees C, and their external morphology was characterized for all pupal stages. The development of olfactory synaptic neuropil was analyzed using anti-synapsin immunocytochemistry, f-actin-phalloidin labeling and confocal microscopy. In the antennal lobes of queens olfactory glomeruli formed approximately 4 days earlier than in workers. The adult number of olfactory glomeruli was in a similar range, but the total glomerular volume was slightly smaller in queens. Olfactory and visual subdivisions (lip, collar) of the mushroom-body calyx formed early, whereas the basal ring separated late. Synaptic microglomeruli in the olfactory lip were established approximately 3-4 days earlier in queens compared to workers. We propose that developmental heterochrony results in fewer synapses in olfactory centers (smaller glomeruli, fewer microglomeruli) in queens, which may result in poorer performance on olfactory learning tasks compared to workers.
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Affiliation(s)
- Claudia Groh
- Department of Behavioral Physiology and Sociobiology, Biozentrum, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
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Benton JL, Sandeman DC, Beltz BS. Nitric oxide in the crustacean brain: regulation of neurogenesis and morphogenesis in the developing olfactory pathway. Dev Dyn 2008; 236:3047-60. [PMID: 17948307 DOI: 10.1002/dvdy.21340] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Nitric oxide (NO) plays major roles during development and in adult organisms. We examined the temporal and spatial patterns of nitric oxide synthase (NOS) appearance in the embryonic lobster brain to localize sources of NO activity; potential NO targets were identified by defining the distribution of NO-induced cGMP. Staining patterns are compared with NOS and cyclic 3,5 guanosine monophosphate (cGMP) distribution in adult lobster brains. Manipulation of NO levels influences olfactory glomerular formation and stabilization, as well as levels of neurogenesis among the olfactory projection neurons. In the first 2 days following ablation of the lateral antennular flagella in juvenile lobsters, a wave of increased NOS immunoreactivity and a reduction in neurogenesis occur. These studies implicate nitric oxide as a developmental architect and also support a role for this molecule in the neural response to injury in the olfactory pathway.
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Affiliation(s)
- J L Benton
- Neuroscience Program, Wellesley College, Wellesley, Massachusetts 02481, USA.
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Utz S, Huetteroth W, Vömel M, Schachtner J. Mas-allatotropin in the developing antennal lobe of the sphinx mothManduca sexta: Distribution, time course, developmental regulation, and colocalization with other neuropeptides. Dev Neurobiol 2008; 68:123-42. [DOI: 10.1002/dneu.20579] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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18
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Yao Y, Wu Y, Yin C, Ozawa R, Aigaki T, Wouda RR, Noordermeer JN, Fradkin LG, Hing H. Antagonistic roles of Wnt5 and the Drl receptor in patterning the Drosophila antennal lobe. Nat Neurosci 2007; 10:1423-32. [PMID: 17934456 DOI: 10.1038/nn1993] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2007] [Accepted: 09/17/2007] [Indexed: 12/30/2022]
Abstract
Numerous studies have shown that ingrowing olfactory axons exert powerful inductive influences on olfactory map development. From an overexpression screen, we have identified wnt5 as a potent organizer of the olfactory map in Drosophila melanogaster. Loss of wnt5 resulted in severe derangement of the glomerular pattern, whereas overexpression of wnt5 resulted in the formation of ectopic midline glomeruli. Cell type-specific cDNA rescue and mosaic experiments showed that wnt5 functions in olfactory neurons. Mutation of the derailed (drl) gene, encoding a receptor for Wnt5, resulted in derangement of the glomerular map, ectopic midline glomeruli and the accumulation of Wnt5 at the midline. We show here that drl functions in glial cells, where it acts upstream of wnt5 to modulate its function in glomerular patterning. Our findings establish wnt5 as an anterograde signal that is expressed by olfactory axons and demonstrate a previously unappreciated, yet powerful, role for glia in patterning the Drosophila olfactory map.
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Affiliation(s)
- Ying Yao
- Neuroscience Program, University of Illinois at Urbana-Champaign, 601 South Goodwin Avenue, Urbana, Illinois 61801, USA
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Boyan GS, Williams JLD. Embryonic development of a peripheral nervous system: nerve tract associated cells and pioneer neurons in the antenna of the grasshopper Schistocerca gregaria. ARTHROPOD STRUCTURE & DEVELOPMENT 2007; 36:336-350. [PMID: 18089112 DOI: 10.1016/j.asd.2007.01.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2006] [Revised: 01/12/2007] [Accepted: 01/31/2007] [Indexed: 05/25/2023]
Abstract
The grasshopper antenna is an articulated appendage associated with the deutocerebral segment of the head. In the early embryo, the meristal annuli of the antenna represent segment borders and are also the site of differentiation of pioneer cells which found the dorsal and ventral peripheral nerve tracts to the brain. We report here on another set of cells which appear earlier than the pioneers during development and are later found arrayed along these tracts at the border of epithelium and lumen. These so-called nerve tract associated cells differ morphologically from pioneers in that they are bipolar, have shorter processes, and are not segmentally organized in the antenna. Nerve tract associated cells do not express horseradish peroxidase and so are not classical neurons. They do not express antigens such as repo and annulin which are associated with glia cells in the nervous system. Nerve tract associated cells do, however, express the mesodermal/mesectodermal cell surface marker Mes-3 and putatively derive from the antennal coelom and then migrate to the epithelium/lumen border. Intracellular recordings show that such nerve tract associated cells have resting potentials similar to those of pioneer cells and can be dye coupled to the pioneers. Similar cell types are present in the maxilla, a serially homologous appendage on the head. The nerve tract associated cells are organized into a cellular scaffold which we speculate may be relevant to the navigation of pioneer and sensory axons in the early embryonic antennal nervous system.
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Affiliation(s)
- G S Boyan
- Developmental Neurobiology Group, Department of Biology II, Section of Neurobiology, Biozentrum, Ludwig-Maximilians-Universität, Grosshadernerstrasse 2, 82152 Planegg-Martinsried, Germany.
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20
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Utz S, Huetteroth W, Wegener C, Kahnt J, Predel R, Schachtner J. Direct peptide profiling of lateral cell groups of the antennal lobes ofManduca sextareveals specific composition and changes in neuropeptide expression during development. Dev Neurobiol 2007; 67:764-77. [PMID: 17443823 DOI: 10.1002/dneu.20381] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The paired antennal lobes are the first integration centers for odor information in the insect brain. In the sphinx moth Manduca sexta, like in other holometabolous insects, they are formed during metamorphosis. To further understand mechanisms involved in the formation of this particularly well investigated brain area, we performed a direct peptide profiling of a well defined cell group (the lateral cell group) of the antennal lobe throughout development by MALDI-TOF mass spectrometry. Although the majority of the about 100 obtained ion signals represent still unknown substances, this first peptidomic characterization of this cell group indicated the occurrence of 12 structurally known neuropeptides. Among these peptides are helicostatin 1, cydiastatins 2, 3, and 4, M. sexta-allatotropin (Mas-AT), M. sexta-FLRFamide (Mas-FLRFamide) I, II, and III, nonblocked Mas-FLRFamide I, and M. sexta-myoinhibitory peptides (Mas-MIPs) III, V, and VI. The identity of two of the allatostatins (cydiastatins 3 and 4) and Mas-AT were confirmed by tandem mass spectrometry (MALDI-TOF/TOF). During development of the antennal lobe, number and frequency of ion signals including those representing known peptides generally increased at the onset of glomeruli formation at pupal Stage P7/8, with cydiastatin 2, helicostatin 1, and Mas-MIP V being the exceptions. Cydiastatin 2 showed transient occurrence mainly during the period of glomerulus formation, helicostatin 1 was restricted to late pupae and adults, while Mas-MIP V occurred exclusively in adult antennal lobes. The power of the applied direct mass spectrometric profiling lies in the possibility of chemically identifying neuropeptides of a given cell population in a fast and reliable manner, at any developmental stage in single specimens. The identification of neuropeptides in the antennal lobes now allows to specifically address the function of these signaling molecules during the formation of the antennal lobe network.
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Affiliation(s)
- Sandra Utz
- Fachbereich Biologie, Tierphysiologie, Philipps Universität, Marburg, Germany
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21
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Watanabe T, Schachtner J, Krizan M, Boretius S, Frahm J, Michaelis T. Manganese-enhanced 3D MRI of established and disrupted synaptic activity in the developing insect brain in vivo. J Neurosci Methods 2007; 158:50-5. [PMID: 16766041 DOI: 10.1016/j.jneumeth.2006.05.012] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2006] [Revised: 05/03/2006] [Accepted: 05/05/2006] [Indexed: 10/24/2022]
Abstract
The antennal lobe of the sphinx moth Manduca sexta serves as a model for the development of the olfactory system. Here, the establishment of the glomerular synaptic network formed by the olfactory receptor axons and antennal lobe neurons at pupal stage P12 was followed by transection of the right antenna and - within 24 h - by injection of MnCl2 into the hemolymph. In vivo 3D MRI at 100 and 60 microm isotropic resolution was then performed at P13 to P17. Whereas the left antennal lobe revealed a pronounced increase of the signal-to-noise ratio (SNR) reflecting normal synaptic activity, the observation of only a small SNR increase within the right antennal lobe indicated the disruption of pertinent activity after antennal transection. The accumulation of manganese in the intact antennal system became observable within 3 h and lasted for at least 2 days after injection. Intra-individual comparisons between the right and left side yielded a statistically significant differential SNR increase in the left antennal lobe. Because such an effect was not observed in younger animals studied at pupal stages P10/P11, the MRI findings confirm the development of functional synapses in the antennal lobe of Manduca sexta by P13.
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Affiliation(s)
- Takashi Watanabe
- Biomedizinische NMR Forschungs GmbH, Max-Planck-Institut für biophysikalische Chemie, 37070 Göttingen, Germany.
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22
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Dacks AM, Christensen TA, Hildebrand JG. Phylogeny of a serotonin-immunoreactive neuron in the primary olfactory center of the insect brain. J Comp Neurol 2006; 498:727-46. [PMID: 16927264 DOI: 10.1002/cne.21076] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Serotonin (5-hydroxytryptamine; 5HT) functions in insects as a neurotransmitter, neuromodulator, and neurohormone. In the sphinx moth Manduca sexta, each of the paired antennal lobes (ALs; the primary olfactory centers in the insect brain) has one 5HT-immunoreactive (5HT-ir) neuron that projects into the protocerebrum, crosses the posterior midline, and innervates the contralateral AL; this is referred to as the contralaterally projecting, serotonin-immunoreactive deutocerebral (CSD) neuron. These neurons are thought to function as centrifugal modulators of olfactory sensitivity. To examine the phylogenetic distribution of 5HT-ir neurons apparently homologous to the CSD neuron, we imaged 5HT-like immunoreactivity in the brains of 40 species of insects belonging to 38 families in nine orders. CSD neurons were found in other Lepidoptera, Trichoptera, Diptera, Coleoptera, and Neuroptera but not in the Hymenoptera. In the paraneopteran and polyneopteran species (insects that undergo incomplete metamorphosis) examined, AL 5HT neurons innervate the ispsilateral AL and project to the protocerebrum. Our findings suggest that the characteristic morphology of the CSD neurons originated in the holometabolous insects (those that undergo complete metamorphosis) and were lost in the Hymenoptera. In a subset of the Diptera, the CSD neurons branch within the contralateral AL and project back to the ipsilateral AL via the antennal commissure. The evolution of AL 5HT neurons is discussed in the context of the physiological actions of 5HT observed in the lepidopteran AL.
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Affiliation(s)
- Andrew M Dacks
- Division of Neurobiology, Arizona Research Laboratories, University of Arizona, Tucson, 85721-0077, USA.
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Lohr C, Bergstein S, Hirnet D. Developmental distribution of CaM kinase II in the antennal lobe of the sphinx moth Manduca sexta. Cell Tissue Res 2006; 327:189-97. [PMID: 16896952 DOI: 10.1007/s00441-006-0249-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2006] [Accepted: 05/15/2006] [Indexed: 01/09/2023]
Abstract
The antennal lobe (primary olfactory center of insects) is completely reorganized during metamorphosis. This reorganization is accompanied by changing patterns of calcium signaling in neurons and glial cells. In the present study, we investigated the developmental distribution of a major calcium-dependent protein, viz., calcium/calmodulin-dependent protein kinase II (CaM kinase II), in the antennal lobe of the sphinx moth Manduca sexta by using a monoclonal antibody. During synaptogenesis (developmental stages 6-10), we found a redistribution of CaM kinase II immunoreactivity, from a homogeneous distribution in the immature neuropil to an accumulation in the neuropil of the glomeruli. CaM kinase II immunoreactivity was less intense in olfactory receptor axons of the antennal nerve and antennal lobe glial cells. Western blot analysis revealed a growing content of CaM kinase II in antennal lobe tissue throughout metamorphosis. Injection of the CaM kinase inhibitor KN-93 into pupae resulted in a reduced number of antennal lobe glial cells migrating into the neuropil to form borders around glomeruli. The results suggest that CaM kinase II is involved in glial cell migration.
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Affiliation(s)
- Christian Lohr
- Abteilung für Allgemeine Zoologie, Fachbereich Biologie, TU Kaiserslautern, Postfach 3049, 67653 Kaiserslautern, Germany.
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24
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Gibson NJ, Tolbert LP. Activation of epidermal growth factor receptor mediates receptor axon sorting and extension in the developing olfactory system of the moth Manduca sexta. J Comp Neurol 2006; 495:554-72. [PMID: 16498681 PMCID: PMC2709604 DOI: 10.1002/cne.20890] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
During development of the adult olfactory system of the moth Manduca sexta, olfactory receptor neurons extend axons from the olfactory epithelium in the antenna into the brain. As they arrive at the brain, interactions with centrally derived glial cells cause axons to sort and fasciculate with other axons destined to innervate the same glomeruli. Here we report studies indicating that activation of the epidermal growth factor receptor (EGFR) is involved in axon ingrowth and targeting. Blocking the EGFR kinase domain pharmacologically leads to stalling of many axons in the sorting zone and nerve layer as well as abnormal axonal fasciculation in the sorting zone. We also find that neuroglian, an IgCAM known to activate the EGFR through homophilic interactions in other systems, is transiently present on olfactory receptor neuron axons and on glia during the critical stages of the sorting process. The neuroglian is resistant to extraction with Triton X-100 in the sorting zone and nerve layer, possibly indicating its stabilization by homophilic binding in these regions. Our results suggest a mechanism whereby neuroglian molecules on axons and possibly sorting zone glia bind homophilically, leading to activation of EGFRs, with subsequent effects on axon sorting, pathfinding, and extension, and glomerulus development.
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Affiliation(s)
- Nicholas J Gibson
- Arizona Research Laboratories Division of Neurobiology, University of Arizona, Tucson, Arizona 85721, USA.
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25
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Vickers NJ, Poole K, Linn CE. Plasticity in central olfactory processing and pheromone blend discrimination following interspecies antennal imaginal disc transplantation. J Comp Neurol 2006; 491:141-56. [PMID: 16127689 PMCID: PMC2638497 DOI: 10.1002/cne.20725] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The antennal imaginal disc was transplanted between premetamorphic male larvae of two different Lepidopteran moth species. Following adult eclosion, electrophysiological recordings were made from 33 central olfactory neurons in the antennal lobes of both Helicoverpa zea donor to Heliothis virescens recipient (Z-V) and reciprocal (V-Z) transplants. Under the influence of sensory neuron input derived from the transplanted antennal imaginal disc, most antennal lobe projection neurons (29/33) were classified as belonging to physiological categories encountered previously in donor species males. Furthermore, when stained many of these neurons had dendritic arbors restricted to donor-induced glomerular locations predicted by their physiology. However, some neurons with unexpected physiological profiles were also identified (4/33), but only in V-Z transplants. These profiles help to explain why some V-Z bilateral transplants were able to respond to both pheromone blends in flight tunnel bioassays, an unforeseen result counter to the assumption that a donor antenna develops a normal donor antennal olfactory receptor neuron complement. Stainings of several neurons in V-Z transplant males also revealed unusual morphological features including multiglomerular dendritic arbors and "incorrect" glomerular locations. These results indicate a developmental plasticity in the final dendritic arborization pattern of central olfactory neurons, including an ability to colonize and integrate inputs across topographically novel donor glomeruli, different from those found in the normal recipient antennal lobe.
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Affiliation(s)
- Neil J Vickers
- Department of Biology, University of Utah, Salt Lake City, Utah 84112, USA.
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26
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Abstract
Calcium signaling studies in invertebrate glial cells have been performed mainly in the nervous systems of the medicinal leech (Hirudo medicinalis) and the sphinx moth Manduca sexta. The main advantages of studing glial cells in invertebrate nervous systems are the large size of invertebrate glial cells and their easy accessibility for optical and electrophysiological recordings. Glial cells in both insects and annelids express voltage-gated calcium channels and, in the case of leech glial cells, calcium-permeable neurotransmitter receptors, which allow calcium influx as one major source for cytosolic calcium transients. Calcium release from intracellular stores can be induced by metabotropic receptor activation in leech glial cells, but appears to play a minor role in calcium signaling. In glial cells of the antennal lobe of Manduca, voltage-gated calcium signaling changes during postembryonic development and is essential for the migration of the glial cells, a key step in axon guidance and in stabilization of the glomerular structures that are characteristic of primary olfactory centers.
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Affiliation(s)
- Christian Lohr
- Abteilung für Allgemeine Zoologie, FB Biologie, TU Kaiserslautern, Postfach 3049, 67653 Kaiserslautern, Germany
| | - Joachim W Deitmer
- Abteilung für Allgemeine Zoologie, FB Biologie, TU Kaiserslautern, Postfach 3049, 67653 Kaiserslautern, Germany
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27
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Perk CG, Mercer AR. Dopamine modulation of honey bee (Apis mellifera) antennal-lobe neurons. J Neurophysiol 2005; 95:1147-57. [PMID: 16282199 DOI: 10.1152/jn.01220.2004] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Primary olfactory centers [antennal lobes (ALs)] of the honey bee brain are invaded by dopamine (DA)-immunoreactive neurons early in development (pupal stage 3), immediately before a period of rapid growth and compartmentalization of the AL neuropil. Here we examine the modulatory actions of DA on honey bee AL neurons during this period. Voltage-clamp recordings in whole cell configuration were used to determine the effects of DA on ionic currents in AL neurons in vitro from pupal bees at stages 4-6 of the nine stages of metamorphic adult development. In approximately 45% of the neurons tested, DA (5-50 x 10(-5) M) reduced the amplitude of outward currents in the cells. In addition to a slowly activating, sustained outward current, DA reduced the amplitude of a rapidly activating, transient outward conductance in some cells. Both of the currents modulated by DA could be abolished by the removal of Ca2+ from the external medium or by treatment of cells with charybdotoxin (2 x 10(-8) M), a blocker of Ca2+-dependent K+ currents in the cells. Ca2+ currents were not affected by DA, nor were A-type K+ currents (I(A)). Results suggest that the delayed rectifier-like current (I(KV)) also remains intact in the presence of DA. Taken together, our data indicate that Ca2+-dependent K+ currents are targets of DA modulation in honey bee AL neurons. This study lends support to the hypothesis that DA plays a role in the developing brain of the bee.
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28
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Wang S, Zhang S, Sato K, Srinivasan MV. Maturation of odor representation in the honeybee antennal lobe. JOURNAL OF INSECT PHYSIOLOGY 2005; 51:1244-54. [PMID: 16183074 DOI: 10.1016/j.jinsphys.2005.07.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2005] [Revised: 07/01/2005] [Accepted: 07/05/2005] [Indexed: 05/04/2023]
Abstract
The antennal lobe (AL) is the first center for processing odors in the insect brain, as is the olfactory bulb (OB) in vertebrates. Both the AL and the OB have a characteristic glomerular structure; odors sensed by olfactory receptor neurons are represented by patterns of glomerular activity. Little is known about when and how an odor begins to be perceived in a developing brain. We address this question by using calcium imaging to monitor odor-evoked neural activity in the ALs of bees of different ages. We find that odor-evoked neural activity already occurs in the ALs of bees as young as 1 or 2 days. In young bees, the responses to odors are relatively weak and restricted to a small number of glomeruli. However, different odors already evoke responses in different combinations of glomeruli. In mature bees, the responses are stronger and are evident in more glomeruli, but continue to have distinct odor-dependent signatures. Our findings indicate that the specific glomerular patterns for odors are conserved during the development, and that odor representations are fully developed in the AL during the first 2 weeks following emergence.
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Affiliation(s)
- Shunpeng Wang
- Center for Visual Sciences, Research School of Biological Sciences, Australian National University, Canberra, Australia.
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29
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Gaudin A, Gascuel J. 3D atlas describing the ontogenic evolution of the primary olfactory projections in the olfactory bulb of Xenopus laevis. J Comp Neurol 2005; 489:403-24. [PMID: 16025461 DOI: 10.1002/cne.20655] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The adult Xenopus presents the unique capability to smell odors both in water and air thanks to two different olfactory pathways. Nevertheless, the tadpole can initially perceive only water-borne odorants, as the olfactory receptor neurons (ORN) that will detect air-borne odorants develop later. Such a phenomenon requires major reorganization processes. Here we focused on the precise description of the neuroanatomical modifications occurring in the olfactory bulb (OB) of the tadpole throughout metamorphosis. Using both carbocyanine dyes and lectin staining, we investigated the evolution of ORN projection patterns into the OB from Stages 47 to 66, thus covering the period of time when all the modifications take place. Although our results confirm previous works (Reiss and Burd [1997] Semin Cell Dev Biol 8:171-179), we showed for the first time that the main olfactory bulb (MOB) is subdivided into seven zones at Stage 47 plus the accessory olfactory bulb (AOB). These seven zones receive fibers dedicated to aquatic olfaction ("aquatic fibers") and are conserved until Stage 66. At Stage 48 the first fibers dedicated to the aerial olfaction constitute a new dorsomedial zone that grows steadily, pushing the seven original zones ventrolaterally. Only the part of the OB receiving aquatic fibers is fragmented, reminiscent of the organization described in fish. This raises the question of whether such an organization in zones constitutes a plesiomorphy or is linked to aquatic olfaction. We generated a 3D atlas at several stages which are representative of the reorganization process. This will be a useful tool for future studies of development and function.
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Affiliation(s)
- Arnaud Gaudin
- Centre des Sciences du Goût (Unité Mixte de Recherche 5170 Centre National de la Recherche Scientifique-Université de Bourgogne-Institut National de la Recherche Agronomique), F-21000 Dijon, France
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Lohr C, Heil JE, Deitmer JW. Blockage of voltage-gated calcium signaling impairs migration of glial cells in vivo. Glia 2005; 50:198-211. [PMID: 15712206 DOI: 10.1002/glia.20163] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Migration of glial cells is an essential step in the development of the antennal lobe, the primary olfactory center of insects, to establish well-defined borders between olfactory glomeruli required for odor discrimination. In the present study, we used two-photon microscopy to visualize calcium signaling in developing antennal lobe glial cells of the sphinx moth Manduca sexta. We found a correlation between the upregulation of functional voltage-gated calcium channels and the onset of glial cell migration. In addition, glial cells migrating into the center of the antennal lobe express larger voltage-gated calcium transients than glial cells that remain at the periphery. Migration behavior and calcium signaling of glial cells in vivo were manipulated either by deafferentation, by injection of the calcium channel blockers diltiazem, verapamil, and flunarizine, or by injection of the calcium chelators BAPTA-AM and Fluo-4-AM. In deafferented antennal lobes, glial cells failed to express functional voltage-gated calcium channels and did not migrate. Calcium channel blockage or reducing glial calcium signals by calcium chelators prevented glial cell migration and resulted in antennal lobes lacking glial borders around glomeruli, indicating that voltage-gated calcium signaling is required for the migration of antennal lobe glial cells and the development of mature olfactory glomeruli.
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Affiliation(s)
- Christian Lohr
- Abteilung für Allgemeine Zoologie, Universität Kaiserslautern, 67653 Kaiserslautern, Germany.
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31
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Utz S, Schachtner J. Development of A-type allatostatin immunoreactivity in antennal lobe neurons of the sphinx moth Manduca sexta. Cell Tissue Res 2005; 320:149-62. [PMID: 15726421 DOI: 10.1007/s00441-004-1059-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2004] [Accepted: 11/23/2004] [Indexed: 11/26/2022]
Abstract
The antennal lobe (AL) of the sphinx moth Manduca sexta is a well-established model system for studying mechanisms of neuronal development. To understand whether neuropeptides are suited to playing a role during AL development, we have studied the cellular localization and temporal expression pattern of neuropeptides of the A-type allatostatin family. Based on morphology and developmental appearance, we distinguished four types of AST-A-immunoreactive cell types. The majority of the cells were local interneurons of the AL (type Ia) which acquired AST-A immunostaining in a complex pattern consisting of three rising (RI-RIII) and two declining phases (DI, DII). Type Ib neurons consisted of two local neurons with large cell bodies not appearing before 7/8 days after pupal ecdysis (P7/P8). Types II and III neurons accounted for single centrifugal neurons, with type II neurons present in the larva and disappearing in the early pupa. The type III neuron did not appear before P7/P8. RI and RII coincided with the rises of the ecdysteroid hemolymph titer. Artificially shifting the pupal 20-hydroxyecdysone (20E) peak to an earlier developmental time point resulted in the precocious appearance of AST-A immunostaining in types Ia, Ib, and III neurons. This result supports the hypothesis that the pupal rise in 20E plays a role in AST-A expression during AL development. Because of their early appearance in newly forming glomeruli, AST-A-immunoreactive fibers could be involved in glomerulus formation. Diffuse AST-A labeling during early AL development is discussed as a possible signal providing information for ingrowing olfactory receptor neurons.
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Affiliation(s)
- Sandra Utz
- Department of Biology, Animal Physiology, Philipps University, 35032, Marburg, Germany
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Huetteroth W, Schachtner J. Standard three-dimensional glomeruli of the Manduca sexta antennal lobe: a tool to study both developmental and adult neuronal plasticity. Cell Tissue Res 2005; 319:513-24. [PMID: 15672266 DOI: 10.1007/s00441-004-1016-1] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2004] [Accepted: 10/05/2004] [Indexed: 10/25/2022]
Abstract
The metamorphosing antennal lobe (AL) of the sphinx moth Manduca sexta serves as an established model system for studying neuronal development. To improve our understanding of mechanisms involved in neuronal plasticity, we have analyzed the size, shape, and localization of ten identified glomeruli at three different time points during development and in the adult, viz., (1) 13 days after pupal eclosion (P13), which reflects a time when the basic glomerular map has formed, (2) immediately after adult eclosion (A0), which represents a time when the newly formed glomeruli are uninfluenced by external odors, and (3) 4 days after adult eclosion (A4), which reflects a time when the animals have been exposed to surrounding odors. Our data from normally developing ALs of male M. sexta from P13 to A0 revealed an increase in size of all examined glomeruli of between 40% and 130%, with the strongest increases occurring in two of the three sex-specific glomeruli (cumulus, toroid). From A0 to A4, the cumulus and toroid increased significantly when correlated to AL volume, whereas the other glomeruli reached the sizes gained after A0. This study was based on antibody staining against the ubiquitous synaptic vesicle protein synaptotagmin, confocal laser scan microscopy, and the three-dimensional (3D) analysis tool AMIRA. Tissue permeability and therefore reliability of the staining quality was enhanced by using formalin/methanol fixation. The standard 3D glomeruli introduced in this study can now be used as basic tools for further examination of neuronal plasticity at the level of the identified neuropil structures, viz., the glomeruli of the AL of M. sexta.
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Affiliation(s)
- Wolf Huetteroth
- Fachbereich Biologie, Tierphysiologie, Philipps-Universität, 35043, Marburg, Germany
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Michaelis T, Watanabe T, Natt O, Boretius S, Frahm J, Utz S, Schachtner J. In vivo 3D MRI of insect brain: cerebral development during metamorphosis of Manduca sexta. Neuroimage 2005; 24:596-602. [PMID: 15627604 DOI: 10.1016/j.neuroimage.2004.08.048] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2004] [Revised: 08/27/2004] [Accepted: 08/27/2004] [Indexed: 10/26/2022] Open
Abstract
High-resolution 3D MRI of male pupae of Manduca sexta was performed at 2.35 T in order to evaluate its potential for an in vivo characterization of insect brain during metamorphosis. T1-weighted 3D FLASH (TR/TE = 20/7.8 ms, 25 degrees flip angle) and T2-weighted 3D fast SE MRI data sets (TR/TEeff = 3000/100 ms) were acquired at different developmental stages with an isotropic resolution of 100 microm. Both T1- and T2-weighted 3D MRI allowed for the identification of cerebral structures such as the antennal nerve, antennal and optical lobe, and central brain. Pronounced developmental alterations of the morphology were observed during metamorphosis. The results demonstrate the feasibility of 3D MRI at nanoliter resolution to identify major brain systems of M. sexta and respective changes during pupal development from caterpillar to sphinx moth. Together with the use of suitable contrast agents, this approach may provide new ways for studying the axonal connectivity and neural function of the developing insect brain.
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Affiliation(s)
- Thomas Michaelis
- Biomedizinische NMR Forschungs GmbH am Max-Planck-Institut für biophysikalische Chemie, Göttingen, Germany.
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Abstract
Synaptic specificity is the culmination of several processes, beginning with the establishment of neuronal subtype identity, followed by navigation of the axon to the correct subdivision of neuropil, and finally, the cell-cell recognition of appropriate synaptic partners. In this review we summarize the work on sensory neurons in crickets, cockroaches, moths, and fruit flies that establishes some of the principles and molecular mechanisms involved in the control of synaptic specificity. The identity of a sensory neuron is controlled by combinatorial expression of transcription factors, the products of patterning and proneural genes. In the nervous system, sensory axon projections are anatomically segregated according to modality, stimulus quality, and cell-body position. A variety of cell-surface and intracellular signaling molecules are used to achieve this. Synaptic target recognition is also controlled by transcription factors such as Engrailed and may be, in part, mediated by cadherin-like molecules.
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Affiliation(s)
- Jonathan M Blagburn
- Institute of Neurobiology, Department of Physiology, Medical Sciences Campus, University of Puerto Rico, San Juan, Puerto Rico 00901-1123.
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Boyan GS, Williams JLD. Embryonic development of the sensory innervation of the antenna of the grasshopper Schistocerca gregaria. ARTHROPOD STRUCTURE & DEVELOPMENT 2004; 33:381-397. [PMID: 18089045 DOI: 10.1016/j.asd.2004.03.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2004] [Accepted: 03/29/2004] [Indexed: 05/25/2023]
Abstract
The establishment of the sensory nervous system of the antenna of the grasshopper Schistocerca gregaria was examined using immunocytochemical methods and in the light of the appendicular and articulated nature of this structure. The former is demonstrated first by the expression pattern of the segment polarity gene engrailed in the head neuromere innervating the antenna, the deutocerebrum. Engrailed expression is present in identified deutocerebral neuroblasts and, as elsewhere in the body, is continuous with cells of the posterior epithelium of the associated appendage, in this case the antenna. Second, early expression of the glial homeobox gene reversed polarity (repo) in the antenna is by a stereotypic pair of cells at the antenna base, a pattern we show is repeated metamerically for each thoracic appendage of the embryo. Subsequently, three regions of Repo expression (A1, A2, A3) are seen within the antenna, and may represent a preliminary form of articulation. Bromodeoxyuridine incorporation reveals that these regions are sites of intense cell differentiation. Neuron-specific horseradish peroxidase and Lazarillo expression confirm that the pioneers of the ventral and dorsal tracts of the antennal sensory nervous system are amongst these differentiating cells. Sets of pioneers appear simultaneously in several bands and project confluent axons towards the antennal base. We conclude that the sensory nervous system of the antenna is not pioneered from the tip of the antenna alone, but in a stepwise manner by cells from several zones. The early sensory nervous systems of antenna, maxilla and leg therefore follow a similar developmental program consistent with their serially homologous nature.
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Affiliation(s)
- G S Boyan
- Developmental Neurobiology Group, Department of Biology II, Ludwig-Maximilians-Universität, Luisenstrasse 14, 80333 Munich, Germany
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36
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Gibson NJ, Hildebrand JG, Tolbert LP. Glycosylation patterns are sexually dimorphic throughout development of the olfactory system in Manduca sexta. J Comp Neurol 2004; 476:1-18. [PMID: 15236463 DOI: 10.1002/cne.20178] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
In the moth Manduca sexta, development of the adult olfactory system depends on complex interactions between olfactory receptor neurons in the antenna, antennal-lobe neurons in the brain, and several classes of glial cells. As one approach to characterizing molecules that may play roles in these interactions, we used lectins to screen antennae and antennal lobes at different stages of adult development. We find that each of the major neural cell types has a distinct pattern of labeling by lectins. Effects of enzymatic and other treatments on lectin labeling lead us to conclude that the predominant lectin ligands are: glycosphingolipids and an O-linked, fucose-containing glycoprotein on axons of olfactory receptor neurons, O-linked glycoproteins on antennal-lobe neurons, and N-linked glycoproteins on all classes of glial cells in the primary olfactory pathway. Wheat germ agglutinin labels all olfactory axons uniformly during much of development, but labeling becomes restricted to the pheromone-responsive olfactory receptor neurons in the adult male. Succinylated WGA reveals differences in these axon classes earlier, as glomerului develop from protoglomeruli. The adult female displays a less pronounced difference in labeling of axons targeting ordinary and sexually dimorphic glomeruli. Differences in labeling of receptor axons targeted to ordinary and sexually dimorphic glomeruli may be correlated with differences in function or connectivity in different regions of the antennal lobe.
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Affiliation(s)
- Nicholas J Gibson
- Arizona Research Laboratories, Division of Neurobiology, University of Arizona, Tucson, Arizona 85721-0077, USA.
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Schachtner J, Trosowski B, D'Hanis W, Stubner S, Homberg U. Development and steroid regulation of RFamide immunoreactivity in antennal-lobe neurons of the sphinx moth Manduca sexta. ACTA ACUST UNITED AC 2004; 207:2389-400. [PMID: 15184511 DOI: 10.1242/jeb.01036] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
During metamorphosis, the insect nervous system undergoes considerable remodeling: new neurons are integrated while larval neurons are remodeled or eliminated. To understand further the mechanisms involved in transforming larval to adult tissue we have mapped the metamorphic changes in a particularly well established brain area, the antennal lobe of the sphinx moth Manduca sexta, using an antiserum recognizing RFamide-related neuropeptides. Five types of RFamide-immunoreactive (ir) neurons could be distinguished in the antennal lobe, based on morphology and developmental appearance. Four cell types (types II-V, each consisting of one or two cells) showed RFamide immunostaining in the larva that persisted into metamorphosis. By contrast, the most prominent group (type I), a mixed population of local and projection neurons consisting of about 60 neurons in the adult antennal lobe, acquired immunostaining in a two-step process during metamorphosis. In a first step, from 5 to 7 days after pupal ecdysis, the number of labeled neurons reached about 25. In a second step, starting about 4 days later, the number of RFamide-ir neurons increased within 6 days to about 60. This two-step process parallels the rise and fall of the developmental hormone 20-hydroxyecdysone (20E) in the hemolymph. Artificially shifting the 20E peak to an earlier developmental time point resulted in the precocious appearance of RFamide immunostaining and led to premature formation of glomeruli. Prolonging high 20E concentrations to stages when the hormone titer starts to decline had no effect on the second increase of immunostained cell numbers. These results support the idea that the rise in 20E, which occurs after pupal ecdysis, plays a role in the first phase of RFamide expression and in glomeruli formation in the developing antennal lobes. The role of 20E in the second phase of RFamide expression is less clear, but increased cell numbers showing RFamide-ir do not appear to be a consequence of the declining levels in 20E that occur during adult development.
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Affiliation(s)
- Joachim Schachtner
- Department of Biology, Animal Physiology, Philipps-University, 35032 Marburg, Germany.
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Hummel T, Zipursky SL. Afferent induction of olfactory glomeruli requires N-cadherin. Neuron 2004; 42:77-88. [PMID: 15066266 DOI: 10.1016/s0896-6273(04)00158-8] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2003] [Revised: 02/13/2004] [Accepted: 03/04/2004] [Indexed: 11/26/2022]
Abstract
Drosophila olfactory receptor neurons (ORNs) elaborate a precise internal representation of the external olfactory world in the antennal lobe (AL), a structure analagous to the vertebrate olfactory bulb. ORNs expressing the same odorant receptor innervate common targets in a highly organized neuropilar structure inside the AL, the glomerulus. During normal development, ORNs target to specific regions of the AL and segregate into subclass-specific aggregates called protoglomeruli prior to extensive intermingling with target dendrites to form mature glomeruli. Using a panel of ORN subclass-specific markers, we demonstrate that in the adult AL, N-cadherin (N-cad) mutant ORN terminals remain segregated from dendrites of target neurons. N-cad plays a crucial role in protoglomerulus formation but is largely dispensible for targeting to the appropriate region of the AL. We propose that N-cad, a homophilic cell adhesion molecule, acts in a permissive fashion to promote subclass-specific sorting of ORN axon terminals into protoglomeruli.
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Affiliation(s)
- Thomas Hummel
- Howard Hughes Medical Institute, Department of Biological Chemistry, Geffen School of Medicine, Molecular Biology Institute, Box 951662, University of California, Los Angeles, Los Angeles, CA 90095, USA
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39
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Tucker ES, Oland LA, Tolbert LP. In vitro analyses of interactions between olfactory receptor growth cones and glial cells that mediate axon sorting and glomerulus formation. J Comp Neurol 2004; 472:478-95. [PMID: 15065121 DOI: 10.1002/cne.20058] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
During development, the axons of olfactory receptor neurons project to the CNS and converge on glomerular targets. For vertebrate and invertebrate olfactory systems, neuron-glia interactions have been hypothesized to regulate the sorting and targeting of olfactory receptor axons and the development of glomeruli. In the moth Manduca sexta, glial reduction experiments have directly implicated two types of central olfactory glia, the sorting zone- and neuropil-associated glia, in key events in olfactory development, including axon sorting and glomerulus stabilization. By using cocultures containing central olfactory glial cells and explants of olfactory receptor epithelium, we show that olfactory receptor growth cones elaborate extensively and cease advancement following contact with sorting zone- and neuropil-associated glial cells. These effects on growth cone behavior were specific to central olfactory glia; peripheral glial cells of the olfactory nerve failed to elicit similar responses in olfactory receptor growth cones. We propose that sorting zone- and neuropil-associated glial cells similarly modify axon behavior in vitro by altering the adhesive properties and cytoskeleton of olfactory receptor growth cones and that these in vitro changes may underlie functionally relevant changes in growth cone behavior in vivo.
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Affiliation(s)
- Eric S Tucker
- Department of Cell Biology and Anatomy, University of Arizona, Tucson, Arizona 85724-5044, USA
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40
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Abstract
We have investigated possible roles of the Eph family receptor tyrosine kinases and their ligand ephrins in the developing primary olfactory nerve pathway in the moth Manduca sexta. The Manduca homologs of the Eph receptor (MsEph) and ephrin ligand (MsEphrin) are most closely related to Drosophila Eph and ephrin, respectively. In situ labeling with Fc-fusion probes, in which IgG Fc was linked to the extracellular domain of MsEph (Eph-Fc) or MsEphrin (ephrin-Fc), reveals that both Eph receptors and ephrins are expressed on axons of olfactory receptor cells (ORCs) during their ingrowth to the primary center, the antennal lobe (AL). Interestingly, Eph receptors and ephrins are differentially distributed among identifiable glomeruli such that glomeruli with high receptor staining show little or no ligand staining, and vice versa, suggesting a complementary Eph-ephrin expression by subsets of ORC axons innervating a particular set of glomeruli. In contrast, neither Eph receptors nor ephrins are detectable in intrinsic components of the AL. In vitro, ephrin-Fc and Eph-Fc, when present homogeneously in the substratum, inhibit neurite outgrowth from olfactory epithelial explants. Moreover, in patterned substratum, neurites growing on the standard substratum turn or stop after encountering the test substratum containing ephrin-Fc. These in vitro observations indicate that MsEphrin can act as an inhibitor/repulsive cue for ORC axons. Based on results from in situ and in vitro experiments, we hypothesize that Eph receptors and ephrins mediate axon sorting and fasciculation through repulsive axon-axon interactions.
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41
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Nezlin LP, Heermann S, Schild D, Rössler W. Organization of glomeruli in the main olfactory bulb of Xenopus laevis tadpoles. J Comp Neurol 2003; 464:257-68. [PMID: 12900923 DOI: 10.1002/cne.10709] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Structural and functional investigations were carried out to study olfactory glomeruli in the main olfactory bulb (OB) in tadpoles of the clawed frog, Xenopus laevis. Calcium imaging of odor response patterns of OB neurons revealed that the synapses within the glomeruli are functional. Tracing axons of individual olfactory receptor neurons (ORNs), dendrites of mitral/tufted (M/T) cells and processes of periglomerular interneurons indicate that the glomerular architecture is solely determined by terminal branches of ORN axons and tufts of M/T primary dendrites. The small population of periglomerular neurons forms wide-field arborizations that always extend over many glomeruli, enter the glomeruli, but lack any glomerular tufts. Antibodies to synaptophysin indicate a high density of synapses within glomeruli, which was further confirmed at the ultrastructural level and quantified to approximately 0.5 synaptic sites per microm(2). Combining immunocytochemistry and ultrastructural investigations, we show that glomeruli in Xenopus laevis tadpoles lack any cellular borders. Glomeruli are surrounded neither by periglomerular somata nor by glial processes. Taken together, our results demonstrate that olfactory glomeruli in Xenopus laevis tadpoles (1) are fully functional, (2) are spheroidal neuropil aggregations of terminal tufts of ORNs and tufts of primary dendrites of M/T cells, and (3) are not enwrapped by a border formed by juxtaglomerular cells.
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Affiliation(s)
- Leonid P Nezlin
- Department of Molecular Neurophysiology, University of Göttingen, 37073 Göttingen, Germany.
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42
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Lohr C. Monitoring neuronal calcium signalling using a new method for ratiometric confocal calcium imaging. Cell Calcium 2003; 34:295-303. [PMID: 12887977 DOI: 10.1016/s0143-4160(03)00105-2] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Ca2+ signalling influences many processes in the adult and developing nervous system like exocytosis, synaptic plasticity, and growth cone motility. Optical techniques in combination with fluorescent Ca2+ indicators are the most frequently used methods to measure Ca2+ signalling in cells. In the present study, a new method for ratiometric confocal Ca2+ imaging was developed, and the usefulness of the system was tested with two different neuronal preparations. Developing Manduca sexta antennal lobe neurons were loaded with the Ca2+-sensitive dye Fura Red-AM, and the ratio of fluorescence excited at 457 and 488nm was measured with a confocal laser scanning microscope. During pupal stages 4-12, the antennal lobe neuropil is restructured which includes the ingrowth of olfactory receptor axons, dendritic outgrowth of antennal lobe neurons, and synaptogenesis. In antennal lobe neurons, application of the AChR agonist carbachol induced Ca2+ oscillations the amplitude and frequency of which changed during stages 4-9, while at the end of synaptogenesis, at stages 11 and 12, only single Ca2+ transients were elicited. The Ca2+ oscillations were blocked by D-tubocurarine and Cd2+, indicating that they were due to Ca2+ influx through voltage-gated Ca2+ channels, activated by nAChR-mediated membrane depolarization. To test whether single action potentials can induce Ca2+ transients detectable by Fura Red, individual leech Retzius neurons were injected iontophoretically with the Ca2+ indicator, and the membrane potential was recorded during Ca2+ imaging. Single action potentials induced transient increases in the Fura Red ratio measured in the axon, while trains of action potentials elicited Ca2+ transients that could also be recorded in the cell body and the nucleus. The results show that Fura Red can be used as a ratiometric Ca2+ indicator for confocal imaging.
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Affiliation(s)
- Christian Lohr
- Abteilung für Allgemeine Zoologie, Universität Kaiserslautern, Postfach 3049, Kaiserslautern 67653, Germany.
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Ang LH, Kim J, Stepensky V, Hing H. Dock and Pak regulate olfactory axon pathfinding in Drosophila. Development 2003; 130:1307-16. [PMID: 12588847 DOI: 10.1242/dev.00356] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The convergence of olfactory axons expressing particular odorant receptor (Or) genes on spatially invariant glomeruli in the brain is one of the most dramatic examples of precise axon targeting in developmental neurobiology. The cellular and molecular mechanisms by which olfactory axons pathfind to their targets are poorly understood. We report here that the SH2/SH3 adapter Dock and the serine/threonine kinase Pak are necessary for the precise guidance of olfactory axons. Using antibody localization, mosaic analyses and cell-type specific rescue, we observed that Dock and Pak are expressed in olfactory axons and function autonomously in olfactory neurons to regulate the precise wiring of the olfactory map. Detailed analyses of the mutant phenotypes in whole mutants and in small multicellular clones indicate that Dock and Pak do not control olfactory neuron (ON) differentiation, but specifically regulate multiple aspects of axon trajectories to guide them to their cognate glomeruli. Structure/function studies show that Dock and Pak form a signaling pathway that mediates the response of olfactory axons to guidance cues in the developing antennal lobe (AL). Our findings therefore identify a central signaling module that is used by ONs to project to their cognate glomeruli.
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Affiliation(s)
- Lay-Hong Ang
- Department of Cell and Structural Biology, University of Illinois at Urbana-Champaign, 601 South Goodwin Avenue, C626, Urbana, IL 61801, USA
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Younossi-Hartenstein A, Salvaterra PM, Hartenstein V. Early development of the Drosophila brain: IV. Larval neuropile compartments defined by glial septa. J Comp Neurol 2003; 455:435-50. [PMID: 12508318 DOI: 10.1002/cne.10483] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
In this study, we have analyzed the architecture of the brain neuropile of the Drosophila larva, which is formed by two main structural elements: long axon tracts and terminal axonal/dendritic arborizations carrying synapses. By using several molecular markers expressed in neurons and glial cells, we show that the early larval neuropile is subdivided by glial sheaths into numerous compartments. The three-dimensional layout of these compartments and their relationship to the pattern of long axon tracts described in the accompanying article (Nassif et al. [2003] J. Comp. Neurol 417-434) was modeled by using a three-dimensional illustration computer software. On the basis of their location relative to each other and to long axon tracts, larval brain compartments can be identified with compartments defined by structural and functional criteria for the adult fly brain. We find that small precursors of most of the compartments of the adult central brain can be identified in the early larva. Changes in brain compartmental organization occurring during larval growth are described. Neuropile compartments, representing easily identifiable landmark structures, will assist in future analyses of Drosophila brain development in which the exact location of neurons and their axonal trajectories is of importance.
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Affiliation(s)
- Amelia Younossi-Hartenstein
- Department of Molecular Cell and Developmental Biology, University of California Los Angeles, Los Angeles, California 90095, USA
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45
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Schachtner J, Huetteroth W, Nighorn A, Honegger HW. Copper/zinc superoxide dismutase-like immunoreactivity in the metamorphosing brain of the sphinx mothManduca sexta. J Comp Neurol 2003; 469:141-52. [PMID: 14689479 DOI: 10.1002/cne.10992] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Cu/Zn superoxide dismutase (SOD) is part of the defense mechanism that protects cells from being damaged by reactive oxygen species. During metamorphosis of the nervous system, neurons undergo various fates, which are all coupled to high metabolic activities, such as proliferation, differentiation, pathfinding, and synaptogenesis. We describe the pattern of SOD immunoreactivity of identified neurons and neuron groups in the brain of Manduca sexta from the late larva through metamorphosis into adult. We focused on neurons of the developing antennal lobes, the optic lobes, and the central brain. Our results indicate the transient expression of SOD during phases in which the neurons develop their final adult identities. Our data also suggest that the SOD immunoreactivity may be used as an indicator for the period in which developing neurons form their synapses. We also observed SOD immunoreactivity within nitric oxide-sensitive cells as characterized by immunolabeling against 3'5'-cyclic guanosine monophosphate and soluble guanylyl cyclase, a novel finding in insects.
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Affiliation(s)
- Joachim Schachtner
- Fachbereich Biologie, Tierphysiologie, Philipps-Universität, 35032 Marburg, Germany.
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46
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Soustelle L, Besson MT, Rival T, Birman S. Terminal glial differentiation involves regulated expression of the excitatory amino acid transporters in the Drosophila embryonic CNS. Dev Biol 2002; 248:294-306. [PMID: 12167405 DOI: 10.1006/dbio.2002.0742] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The Drosophila excitatory amino acid transporters dEAAT1 and dEAAT2 are nervous-specific transmembrane proteins that mediate the high affinity uptake of L-glutamate or aspartate into cells. Here, we demonstrate by colocalization studies that both genes are expressed in discrete and partially overlapping subsets of differentiated glia and not in neurons in the embryonic central nervous system (CNS). We show that expression of these transporters is disrupted in mutant embryos deficient for the glial fate genes glial cells missing (gcm) and reversed polarity (repo). Conversely, ectopic expression of gcm in neuroblasts, which forces all nerve cells to adopt a glial fate, induces an ubiquitous expression of both EAAT genes in the nervous system. We also detected the dEAAT transcripts in the midline glia in late embryos and dEAAT2 in a few peripheral neurons in head sensory organs. Our results show that glia play a major role in excitatory amino acid transport in the Drosophila CNS and that regulated expression of the dEAAT genes contributes to generate the functional diversity of glial cells during embryonic development.
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Affiliation(s)
- Laurent Soustelle
- Laboratoire de Génétique et Physiologie du Développement, CNRS-Université de la Méditerranée, Developmental Biology Institute of Marseille, Campus de Luminy case 907, 13288 Marseille Cedex 09, France
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47
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Lohr C, Tucker E, Oland LA, Tolbert LP. Development of depolarization-induced calcium transients in insect glial cells is dependent on the presence of afferent axons. JOURNAL OF NEUROBIOLOGY 2002; 52:85-98. [PMID: 12124748 DOI: 10.1002/neu.10075] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Changes in the intracellular Ca(2+) concentration ([Ca(2+)](i)) induced by depolarization have been measured in glial cells acutely isolated from antennal lobes of the moth Manduca sexta at different postembryonic developmental stages. Depolarization of the glial cell membrane was elicited by increasing the external K(+) concentration from 4 to 25 mM. At midstage 5 and earlier stages, less than 20% of the cells responded to 25 mM K(+) (1 min) with a transient increase in [Ca(2+)](i) of approximately 40 nM. One day later, at late stage 5, 68% of the cells responded to 25 mM K(+), the amplitude of the [Ca(2+)](i) transients averaging 592 nM. At later stages, all cells responded to 25 mM K(+) with [Ca(2+)](i) transients with amplitudes not significantly different from those at late stage 5. In stage 6 glial cells isolated from deafferented antennal lobes, i.e., from antennal lobes chronically deprived of olfactory receptor axons, only 30% of the cells responded with [Ca(2+)](i) transients. The amplitudes of these [Ca(2+)](i) transients averaged 93 nM and were significantly smaller than those in normal stage 6 glial cells. [Ca(2+)](i) transients were greatly reduced in Ca(2+)-free, EGTA-buffered saline, and in the presence of the Ca(2+) channel blockers cadmium and verapamil. The results suggest that depolarization of the cell membrane induces Ca(2+) influx through voltage-activated Ca(2+) channels into antennal lobe glial cells. The development of the depolarization-induced Ca(2+) transients is rapid between midstage 5 and stage 6, and depends on the presence of afferent axons from the olfactory receptor cells in the antenna.
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Affiliation(s)
- Christian Lohr
- ARL Division of Neurobiology, University of Arizona, P.O. Box 210077, Tucson, Arizona 85721-0077, USA.
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48
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Oland LA, Tolbert LP. Key interactions between neurons and glial cells during neural development in insects. ANNUAL REVIEW OF ENTOMOLOGY 2002; 48:89-110. [PMID: 12194908 DOI: 10.1146/annurev.ento.48.091801.112654] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Nervous system function is entirely dependent on the intricate and precise pattern of connections made by individual neurons. Much of the insightful research into mechanisms underlying the development of this pattern of connections has been done in insect nervous systems. Studies of developmental mechanisms have revealed critical interactions between neurons and glia, the non-neuronal cells of the nervous system. Glial cells provide trophic support for neurons, act as struts for migrating neurons and growing axons, form boundaries that restrict neuritic growth, and have reciprocal interactions with neurons that govern specification of cell fate and axonal pathfinding. The molecular mechanisms underlying these interactions are beginning to be understood. Because many of the cellular and molecular mechanisms underlying neural development appear to be common across disparate insect species, and even between insects and vertebrates, studies in developing insect nervous systems are elucidating mechanisms likely to be of broad significance.
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Affiliation(s)
- Lynne A Oland
- Arizona Research Laboratories Division of Neurobiology, University of Arizona, Tucson, Arizona 85721, USA.
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Mercer AR, Hildebrand JG. Developmental changes in the electrophysiological properties and response characteristics of Manduca antennal-lobe neurons. J Neurophysiol 2002; 87:2650-63. [PMID: 12037168 DOI: 10.1152/jn.2002.87.6.2650] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Using whole cell patch-clamp recordings, we have examined changes in the electrophysiological properties and response characteristics of antennal lobe (AL) neurons associated with the metamorphic adult development of the sphinx moth, Manduca sexta. Whole cell current profiles and electrical excitability were examined in dispersed AL neurons in vitro, and in medial-group AL neurons in situ in semi-intact brain preparations. Around stages 2-4 of the 18 stages of metamorphic adult development, whole cell current profiles were dominated by large outward (K+) currents. Calcium-dependent action potentials could be elicited at this stage, but only a small percentage of cells exhibited sodium spikes. From stages 3 to 10, there was a rapid increase in the proportion of AL neurons exhibiting rapidly activating, transient sodium currents, and many cells in vitro exhibited spontaneous bursts of spike activity at this time. As development progressed, action-potential waveforms became shorter in duration and larger in amplitude. Cell-type-specific differences in the prevalence of spontaneous activity, and in the electrophysiological properties and response characteristics of AL neurons, were most apparent late in metamorphosis. While removal of antennal sensory input to the ALs early (stage 1-2) in metamorphosis had no detectable effect on the development of cell excitability, a significantly higher percentage of neurons in vitro from stage 4 pupae exhibited sodium-based action potentials following the addition of serotonin to the culture medium. Characteristic forms of electrical excitability in developing Manduca AL neurons, and their modulation by serotonin, seem likely to play a central role in the functional development of the ALs.
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Affiliation(s)
- Alison R Mercer
- Department of Zoology, University of Otago, Dunedin, New Zealand.
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Mercer AR, Hildebrand JG. Developmental changes in the density of ionic currents in antennal-lobe neurons of the sphinx moth, Manduca sexta. J Neurophysiol 2002; 87:2664-75. [PMID: 12037169 DOI: 10.1152/jn.2002.87.6.2664] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Early in metamorphic adult development, action potentials elicited from Manduca sexta antennal lobe neurons are small in amplitude, long in duration, and calcium dependent. As development proceeds, the action potential waveform becomes larger in amplitude, shorter in duration, and increasingly sodium dependent. Whole cell voltage-clamp analysis of Manduca antennal-lobe neurons in vitro has been used to identify voltage-activated currents that contribute to developmental changes in the electrical excitability of these cells. Proximal Branching neurons [putative projection (output) neurons] and Rick Rack neurons (putative local antennal-lobe interneurons) are examined in detail early (pupal stage 5) and late (pupal stage 14) in adult metamorphosis. In both cell types, four voltage-gated and two calcium-dependent ionic currents have been identified. Cell-type-specific changes in the density of sodium, calcium, and potassium currents correlate temporally with changes in cell excitability and spike waveform. Developmental changes in ionic current profiles are accompanied also by the emergence of cell-type-specific response characteristics in the cells. Together with the accompanying paper, this study provides an important foundation for examining the impact of developmental changes in electrical excitability on the growth, electrical properties and connectivity of neurons in central olfactory pathways of the moth.
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Affiliation(s)
- Alison R Mercer
- Department of Zoology, University of Otago, Dunedin, New Zealand.
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