1
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Valamparamban GF, Spéder P. Homemade: building the structure of the neurogenic niche. Front Cell Dev Biol 2023; 11:1275963. [PMID: 38107074 PMCID: PMC10722289 DOI: 10.3389/fcell.2023.1275963] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Accepted: 11/16/2023] [Indexed: 12/19/2023] Open
Abstract
Neural stem/progenitor cells live in an intricate cellular environment, the neurogenic niche, which supports their function and enables neurogenesis. The niche is made of a diversity of cell types, including neurons, glia and the vasculature, which are able to signal to and are structurally organised around neural stem/progenitor cells. While the focus has been on how individual cell types signal to and influence the behaviour of neural stem/progenitor cells, very little is actually known on how the niche is assembled during development from multiple cellular origins, and on the role of the resulting topology on these cells. This review proposes to draw a state-of-the art picture of this emerging field of research, with the aim to expose our knowledge on niche architecture and formation from different animal models (mouse, zebrafish and fruit fly). We will span its multiple aspects, from the existence and importance of local, adhesive interactions to the potential emergence of larger-scale topological properties through the careful assembly of diverse cellular and acellular components.
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Affiliation(s)
| | - Pauline Spéder
- Institut Pasteur, Université Paris Cité, CNRS UMR3738, Structure and Signals in the Neurogenic Niche, Paris, France
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2
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Dunton AD, Göpel T, Ho DH, Burggren W. Form and Function of the Vertebrate and Invertebrate Blood-Brain Barriers. Int J Mol Sci 2021; 22:ijms222212111. [PMID: 34829989 PMCID: PMC8618301 DOI: 10.3390/ijms222212111] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Revised: 10/23/2021] [Accepted: 10/28/2021] [Indexed: 12/25/2022] Open
Abstract
The need to protect neural tissue from toxins or other substances is as old as neural tissue itself. Early recognition of this need has led to more than a century of investigation of the blood-brain barrier (BBB). Many aspects of this important neuroprotective barrier have now been well established, including its cellular architecture and barrier and transport functions. Unsurprisingly, most research has had a human orientation, using mammalian and other animal models to develop translational research findings. However, cell layers forming a barrier between vascular spaces and neural tissues are found broadly throughout the invertebrates as well as in all vertebrates. Unfortunately, previous scenarios for the evolution of the BBB typically adopt a classic, now discredited 'scala naturae' approach, which inaccurately describes a putative evolutionary progression of the mammalian BBB from simple invertebrates to mammals. In fact, BBB-like structures have evolved independently numerous times, complicating simplistic views of the evolution of the BBB as a linear process. Here, we review BBBs in their various forms in both invertebrates and vertebrates, with an emphasis on the function, evolution, and conditional relevance of popular animal models such as the fruit fly and the zebrafish to mammalian BBB research.
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Affiliation(s)
- Alicia D. Dunton
- Developmental Integrative Biology Group, Department of Biological Sciences, University of North Texas, Denton, TX 76203, USA; (T.G.); (W.B.)
- Correspondence:
| | - Torben Göpel
- Developmental Integrative Biology Group, Department of Biological Sciences, University of North Texas, Denton, TX 76203, USA; (T.G.); (W.B.)
| | - Dao H. Ho
- Department of Clinical Investigation, Tripler Army Medical Center, Honolulu, HI 96859, USA;
| | - Warren Burggren
- Developmental Integrative Biology Group, Department of Biological Sciences, University of North Texas, Denton, TX 76203, USA; (T.G.); (W.B.)
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3
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Rittschof CC, Schirmeier S. Insect models of central nervous system energy metabolism and its links to behavior. Glia 2017; 66:1160-1175. [DOI: 10.1002/glia.23235] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2017] [Revised: 08/30/2017] [Accepted: 09/08/2017] [Indexed: 11/11/2022]
Affiliation(s)
- Clare C. Rittschof
- Department of Entomology; College of Agriculture, Food, and the Environment, University of Kentucky; Lexington Kentucky
| | - Stefanie Schirmeier
- Institut für Neuro-und Verhaltensbiologie, University of Münster; Münster Germany
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4
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Weiler A, Volkenhoff A, Hertenstein H, Schirmeier S. Metabolite transport across the mammalian and insect brain diffusion barriers. Neurobiol Dis 2017; 107:15-31. [PMID: 28237316 DOI: 10.1016/j.nbd.2017.02.008] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Revised: 01/02/2017] [Accepted: 02/20/2017] [Indexed: 12/31/2022] Open
Abstract
The nervous system in higher vertebrates is separated from the circulation by a layer of specialized endothelial cells. It protects the sensitive neurons from harmful blood-derived substances, high and fluctuating ion concentrations, xenobiotics or even pathogens. To this end, the brain endothelial cells and their interlinking tight junctions build an efficient diffusion barrier. A structurally analogous diffusion barrier exists in insects, where glial cell layers separate the hemolymph from the neural cells. Both types of diffusion barriers, of course, also prevent influx of metabolites from the circulation. Because neuronal function consumes vast amounts of energy and necessitates influx of diverse substrates and metabolites, tightly regulated transport systems must ensure a constant metabolite supply. Here, we review the current knowledge about transport systems that carry key metabolites, amino acids, lipids and carbohydrates into the vertebrate and Drosophila brain and how this transport is regulated. Blood-brain and hemolymph-brain transport functions are conserved and we can thus use a simple, genetically accessible model system to learn more about features and dynamics of metabolite transport into the brain.
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Affiliation(s)
- Astrid Weiler
- Institut für Neuro- und Verhaltensbiologie, Universität Münster, Badestr. 9, 48149 Münster, Germany
| | - Anne Volkenhoff
- Institut für Neuro- und Verhaltensbiologie, Universität Münster, Badestr. 9, 48149 Münster, Germany
| | - Helen Hertenstein
- Institut für Neuro- und Verhaltensbiologie, Universität Münster, Badestr. 9, 48149 Münster, Germany
| | - Stefanie Schirmeier
- Institut für Neuro- und Verhaltensbiologie, Universität Münster, Badestr. 9, 48149 Münster, Germany.
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5
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DeSalvo MK, Hindle SJ, Rusan ZM, Orng S, Eddison M, Halliwill K, Bainton RJ. The Drosophila surface glia transcriptome: evolutionary conserved blood-brain barrier processes. Front Neurosci 2014; 8:346. [PMID: 25426014 PMCID: PMC4224204 DOI: 10.3389/fnins.2014.00346] [Citation(s) in RCA: 84] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Accepted: 10/10/2014] [Indexed: 12/29/2022] Open
Abstract
Central nervous system (CNS) function is dependent on the stringent regulation of metabolites, drugs, cells, and pathogens exposed to the CNS space. Cellular blood-brain barrier (BBB) structures are highly specific checkpoints governing entry and exit of all small molecules to and from the brain interstitial space, but the precise mechanisms that regulate the BBB are not well understood. In addition, the BBB has long been a challenging obstacle to the pharmacologic treatment of CNS diseases; thus model systems that can parse the functions of the BBB are highly desirable. In this study, we sought to define the transcriptome of the adult Drosophila melanogaster BBB by isolating the BBB surface glia with fluorescence activated cell sorting (FACS) and profiling their gene expression with microarrays. By comparing the transcriptome of these surface glia to that of all brain glia, brain neurons, and whole brains, we present a catalog of transcripts that are selectively enriched at the Drosophila BBB. We found that the fly surface glia show high expression of many ATP-binding cassette (ABC) and solute carrier (SLC) transporters, cell adhesion molecules, metabolic enzymes, signaling molecules, and components of xenobiotic metabolism pathways. Using gene sequence-based alignments, we compare the Drosophila and Murine BBB transcriptomes and discover many shared chemoprotective and small molecule control pathways, thus affirming the relevance of invertebrate models for studying evolutionary conserved BBB properties. The Drosophila BBB transcriptome is valuable to vertebrate and insect biologists alike as a resource for studying proteins underlying diffusion barrier development and maintenance, glial biology, and regulation of drug transport at tissue barriers.
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Affiliation(s)
- Michael K DeSalvo
- Department of Anesthesia and Perioperative Care, University of California San Francisco San Francisco, CA, USA
| | - Samantha J Hindle
- Department of Anesthesia and Perioperative Care, University of California San Francisco San Francisco, CA, USA
| | - Zeid M Rusan
- Department of Anesthesia and Perioperative Care, University of California San Francisco San Francisco, CA, USA
| | - Souvinh Orng
- Department of Anesthesia and Perioperative Care, University of California San Francisco San Francisco, CA, USA
| | - Mark Eddison
- Janelia Farm Research Campus, The Howard Hughes Medical Institute Ashburn, VA, USA
| | - Kyle Halliwill
- Pharmaceutical Sciences and Pharmacogenomics, University of California San Francisco San Francisco, CA, USA
| | - Roland J Bainton
- Department of Anesthesia and Perioperative Care, University of California San Francisco San Francisco, CA, USA
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6
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The Aqueous Extract of Rhizome of Gastrodia elata Protected Drosophila and PC12 Cells against Beta-Amyloid-Induced Neurotoxicity. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2013; 2013:516741. [PMID: 24174977 PMCID: PMC3794658 DOI: 10.1155/2013/516741] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/07/2013] [Accepted: 07/30/2013] [Indexed: 12/13/2022]
Abstract
This study aims to investigate the neuroprotective effect of the rhizome of Gastrodia elata (GE) aqueous extract on beta-amyloid(Aβ)-induced toxicity in vivo and in vitro. Transgenic Drosophila mutants with Aβ-induced neurodegeneration in pan-neuron and ommatidia were used to determine the efficacy of GE. The antiapoptotic and antioxidative mechanisms of GE were also studied in Aβ-treated pheochromocytoma (PC12) cells. In vivo studies demonstrated that GE (5 mg/g Drosophila media)-treated Drosophila possessed a longer lifespan, better locomotor function, and less-degenerated ommatidia when compared with the Aβ-expressing control (all P < 0.05). In vitro studies illustrated that GE increased the cell viability of Aβ-treated PC12 cells in dose-dependent manner, probably through attenuation of Aβ-induced oxidative and apoptotic stress. GE also significantly upregulated the enzymatic activities of catalase, superoxide dismutase, and glutathione peroxidase, leading to the decrease of reactive oxidation species production and apoptotic marker caspase-3 activity. In conclusion, our current data presented the first evidence that the aqueous extract of GE was capable of reducing the Aβ-induced neurodegeneration in Drosophila, possibly through inhibition of apoptosis and reduction of oxidative stress. GE aqueous extract could be developed as a promising herbal agent for neuroprotection and novel adjuvant therapies for Alzheimer's disease.
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7
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Mutunga JM, Boina DR, Anderson TD, Bloomquist JR, Carlier PR, Wong DM, Lam PCH, Totrov MM. Neurotoxicology of bis(n)-tacrines on Blattella germanica and Drosophila melanogaster acetylcholinesterase. ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY 2013; 83:180-194. [PMID: 23740645 PMCID: PMC4739519 DOI: 10.1002/arch.21104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
A series of bis(n)-tacrines were used as pharmacological probes of the acetylcholinesterase (AChE) catalytic and peripheral sites of Blattella germanica and Drosophila melanogaster, which express AChE-1 and AChE-2 isoforms, respectively. In general, the potency of bis(n)-tacrines was greater in D. melanogaster AChE (DmAChE) than in B. germanica AChE (BgAChE). The change in potency with tether length was high in DmAChE and low in BgAChE, associated with 90-fold and 5.2-fold maximal potency gain, respectively, compared to the tacrine monomer. The optimal tether length for Blattella was 8 carbons and for Drosophila was 10 carbons. The two species differed by only about twofold in their sensitivity to tacrine monomer, indicating that differential potency occurred among dimeric bis(n)-tacrines due to structural differences in the peripheral site. Multiple sequence alignment and in silico homology modeling suggest that aromatic residues of DmAChE confer higher affinity binding, and the lack of same at the BgAChE peripheral site may account, at least in part, to the greater overall sensitivity of DmAChE to bis(n)-tacrines, as reflected by in vitro assay data. Topical and injection assays in cockroaches found minimal toxicity of bis(n)-tacrines. Electrophysiological studies on D. melanogaster central nervous system showed that dimeric tacrines do not readily cross the blood brain barrier, explaining the observed nonlethality to insects. Although the bis(n)-tacrines were not good insecticide candidates, the information obtained in this study should aid in the design of selective bivalent ligands targeting insect, pests, and disease vectors.
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Affiliation(s)
- James M Mutunga
- Department of Entomology, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
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8
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Otopalik AG, Shin J, Beltz BS, Sandeman DC, Kolodny NH. Differential uptake of MRI contrast agents indicates charge-selective blood-brain interface in the crayfish. Cell Tissue Res 2012; 349:493-503. [DOI: 10.1007/s00441-012-1413-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2011] [Accepted: 03/19/2012] [Indexed: 11/28/2022]
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9
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Gladstone M, Su TT. Chemical genetics and drug screening in Drosophila cancer models. J Genet Genomics 2011; 38:497-504. [PMID: 22035870 DOI: 10.1016/j.jgg.2011.09.003] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2011] [Revised: 09/10/2011] [Accepted: 09/10/2011] [Indexed: 01/05/2023]
Abstract
Drug candidates often fail in preclinical and clinical testing because of reasons of efficacy and/or safety. It would be time- and cost-efficient to have screening models that reduce the rate of such false positive candidates that appear promising at first but fail later. In this regard, it would be particularly useful to have a rapid and inexpensive whole animal model that can pre-select hits from high-throughput screens but before testing in costly rodent assays. Drosophila melanogaster has emerged as a potential whole animal model for drug screening. Of particular interest have been drugs that must act in the context of multi-cellularity such as those for neurological disorders and cancer. A recent review provides a comprehensive summary of drug screening in Drosophila, but with an emphasis on neurodegenerative disorders. Here, we review Drosophila screens in the literature aimed at cancer therapeutics.
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Affiliation(s)
- Mara Gladstone
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, USA
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10
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Hartenstein V. Morphological diversity and development of glia in Drosophila. Glia 2011; 59:1237-52. [PMID: 21438012 DOI: 10.1002/glia.21162] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2010] [Accepted: 01/25/2011] [Indexed: 12/31/2022]
Abstract
Insect glia represents a conspicuous and diverse population of cells and plays a role in controlling neuronal progenitor proliferation, axonal growth, neuronal differentiation and maintenance, and neuronal function. Genetic studies in Drosophila have elucidated many aspects of glial structure, function, and development. Just as in vertebrates, it appears as if different classes of glial cells are specialized for different functions. On the basis of topology and cell shape, glial cells of the central nervous system fall into three classes (Fig. 1A-C): (i) surface glia that extend sheath-like processes to wrap around the entire brain; (ii) cortex glia (also called cell body-associated glia) that encapsulate neuronal somata and neuroblasts which form the outer layer (cortex) of the central nervous system; (iii) neuropile glia that are located at the interface between the cortex and the neuropile, the central domain of the nervous system formed by the highly branched neuronal processes and their synaptic contacts. Surface glia is further subdivided into an outer, perineurial layer, and an inner, subperineurial layer. Likewise, neuropile glia comprises a class of cells that remain at the surface of the neuropile (ensheathing glia), and a second class that forms profuse lamellar processes around nerve fibers within the neuropile (astrocyte-like or reticular glia). Glia also surrounds the peripheral nerves and sensory organs; here, one also recognizes perineurial and subperineurial glia, and a third type called "wrapping glia" that most likely corresponds to the ensheathing glia of the central nervous system. Much more experimental work is needed to determine how fundamental these differences between classes of glial cells are, or how and when during development they are specified. To aid in this work the following review will briefly summarize our knowledge of the classes of glial cells encountered in the Drosophila nervous system, and then survey their development from the embryo to adult.
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Affiliation(s)
- Volker Hartenstein
- Department of Molecular Cell and Developmental Biology, University of California Los Angeles, Los Angeles, California 90095, USA.
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11
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Leiserson WM, Keshishian H. Maintenance and regulation of extracellular volume and the ion environment in Drosophila larval nerves. Glia 2011; 59:1312-21. [PMID: 21305613 DOI: 10.1002/glia.21132] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2010] [Accepted: 12/01/2010] [Indexed: 11/07/2022]
Abstract
In mammals and insects, paracellular blood barriers isolate the nervous system from the rest of the animal. Glia and accessory cells of the nervous system use pumps, channels, cotransporters, and exchangers collectively to maintain the extracellular ion environment and osmotic balance in the nervous system. At present, the molecular mechanisms that regulate this process remain unclear. In humans, loss of extracellular ion and volume regulation in the nervous system poses serious health threats. Drosophila is a model genetic organism with a proven track record for uncovering molecular mechanisms relevant to human health and disease. Here, we review what is known about extracellular ion and volume regulation in larval abdominal nerves, present some new data about the impact of neural activity on the extracellular environment, and relate the findings to mammalian systems. Homologies have been found at the level of morphology, physiology, molecular mechanisms, and mutant phenotypes. The Fray-Ncc69 module regulates extracellular volume in larval nerves. Genetic rescue experiments with the mammalian orthologs prove this module has a direct correlate in humans. This and other molecular homologies, together with the similar physiological needs, suggest that uncovering the molecular mechanisms of ion and volume regulation in larval nerves will likely provide significant insights into this process in mammalian systems.
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Affiliation(s)
- William M Leiserson
- Molecular, Cellular, and Developmental Biology Department, Yale University, P.O. Box 208103, New Haven, Connecticut 06520-8103, USA.
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12
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Abstract
The ensheathment of neurons and their axons creates an ion-sensitive microenvironment that allows rapid conduction of nerve impulses. One of the fundamental questions about axonal ensheathment is how insulating glial cells wrap around axons. The mechanisms that underlie insulation of axons in invertebrates and vertebrates are not fully understood. In the present article we address cellular aspects of axonal ensheathment in Drosophila by taking advantage of glial mutants that illustrate a range of phenotypic defects including ensheathment of axons. From the findings of these mutant studies, we summarize that loss of glial cells, defects in glial membrane wrapping, failure of glial migration, and loss of specialized ladderlike septate junctions between ensheathing glial membranes result in axon-glial functional defects. These studies provide a broad perspective on glial ensheathment of axons in Drosophila and key insights into the anatomical and cellular aspects of axonal insulation. Given the powerful genetic approaches available in Drosophila, the axonal ensheathment process can be dissected in great detail to reveal the fundamental principles of ensheathment. These observations will be relevant to understanding the very similar processes in vertebrates, where defects in glial cell functions lead to devastating neurological diseases.
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Affiliation(s)
- Swati Banerjee
- Department of Cell and Molecular Physiology, Neurodevelopmental Disorders Research Center, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599-7545, USA
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13
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Banerjee S, Pillai AM, Paik R, Li J, Bhat MA. Axonal ensheathment and septate junction formation in the peripheral nervous system of Drosophila. J Neurosci 2006; 26:3319-29. [PMID: 16554482 PMCID: PMC6674093 DOI: 10.1523/jneurosci.5383-05.2006] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Axonal insulation is critical for efficient action potential propagation and normal functioning of the nervous system. In Drosophila, the underlying basis of nerve ensheathment is the axonal insulation by glial cells and the establishment of septate junctions (SJs) between glial cell membranes. However, the details of the cellular and molecular mechanisms underlying axonal insulation and SJ formation are still obscure. Here, we report the characterization of axonal insulation in the Drosophila peripheral nervous system (PNS). Targeted expression of tau-green fluorescent protein in the glial cells and ultrastructural analysis of the peripheral nerves allowed us to visualize the glial ensheathment of axons. We show that individual or a group of axons are ensheathed by inner glial processes, which in turn are ensheathed by the outer perineurial glial cells. SJs are formed between the inner and outer glial membranes. We also show that Neurexin IV, Contactin, and Neuroglian are coexpressed in the peripheral glial membranes and that these proteins exist as a complex in the Drosophila nervous system. Mutations in neurexin IV, contactin, and neuroglian result in the disruption of blood-nerve barrier function in the PNS, and ultrastructural analyses of the mutant embryonic peripheral nerves show loss of glial SJs. Interestingly, the murine homologs of Neurexin IV, Contactin, and Neuroglian are expressed at the paranodal SJs and play a key role in axon-glial interactions of myelinated axons. Together, our data suggest that the molecular machinery underlying axonal insulation and axon-glial interactions may be conserved across species.
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14
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Freeman MR, Doherty J. Glial cell biology in Drosophila and vertebrates. Trends Neurosci 2006; 29:82-90. [PMID: 16377000 DOI: 10.1016/j.tins.2005.12.002] [Citation(s) in RCA: 178] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2005] [Revised: 10/21/2005] [Accepted: 12/06/2005] [Indexed: 11/22/2022]
Abstract
Glia are the most abundant cell type in the mammalian nervous system and they have vital roles in neural development, function and health. However our understanding of the biology of glia is in its infancy. How do glia develop and interact with neurons? How diverse are glial populations? What are the primary functions of glia in the mature nervous system? These questions can be addressed incisively in the Drosophila nervous system--this contains relatively few glia, which are well-defined histologically and amenable to powerful molecular-genetic analyses. Here, we highlight several developmental, morphological and functional similarities between Drosophila and vertebrate glia. The striking parallels that emerge from this comparison argue that invertebrate model organisms such as Drosophila have excellent potential to add to our understanding of fundamental aspects of glial biology.
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Affiliation(s)
- Marc R Freeman
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, MA 01605-2324, USA.
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15
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Kretzschmar D, Pflugfelder GO. Glia in development, function, and neurodegeneration of the adult insect brain. Brain Res Bull 2002; 57:121-31. [PMID: 11827744 DOI: 10.1016/s0361-9230(01)00643-8] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Glial cells have long been viewed as a passive framework for neurons but in the meanwhile were shown to play a much more active role in brain function and development. Several reviews have described the function of glia in the insect embryo. The focus of this review is the role of glial cells in the development and function of the normal and diseased adult brain. In different insect species, a considerable variety of central nervous system glia has been described indicating adaptation to different functional requirements. In the development of the adult visual and olfactory system, glial cells guide incoming axons acting as intermediate targets. Glia are part of the insect blood-brain barrier, provide nourishment for neurons, and help to regulate the extracellular concentration of ions and neurotransmitters. To fulfill these tasks insect glial cells, like vertebrate glia, interact with each other and with neurons, thus influencing neural activity. The examples presented suggest that crosstalk between all brain cells is necessary not only to develop and maintain the complex insect brain but also to endow it with the capacity to respond and adapt to the changing environment.
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Affiliation(s)
- D Kretzschmar
- Institut für Genetik und Neurobiologie, Biozentrum, Universität Würzburg, Würzburg, Germany.
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16
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O'Connor KR, Beyenbach KW. Chloride channels in apical membrane patches of stellate cells of Malpighian tubules of Aedes aegypti. J Exp Biol 2001; 204:367-78. [PMID: 11136622 DOI: 10.1242/jeb.204.2.367] [Citation(s) in RCA: 25] [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
Stellate cells of Aedes aegypti Malpighian tubules were investigated using patch-clamp methods to probe the route of transepithelial Cl(−) secretion. Two types of Cl(−) channel were identified in excised, inside-out apical membrane patches. The first Cl(−) channel, type I, had a conductance of 24 pS, an open probability of 0.816+/−0.067, an open time of 867+/−114 ms (mean +/− s.e.m., four patches) and the selectivity sequence I(−)>Cl(−)(much greater than) isethionate>gluconate. The I(−)/Cl(−)>>isethionate>gluconate. The I(−)Cl(−) permeability ratio was 1.48, corresponding to Eisenman sequence I. The type I Cl(−) channel was blocked by 2,2′-iminodibenzoic acid (DPC) and niflumic acid (2-[3-(trifluoromethyl)anilo]nicotinic acid). The removal of Ca(2+) from the Ringer's solution on the cytoplasmic side had no effect on channel activity. The second Cl(−) channel, type II, had a conductance of 8 pS, an open probability of 0.066+/−0.021 and an open time of 7.53+/−1.46 ms (mean +/− s.e.m., four patches). The high density and halide selectivity sequence of the type I Cl(−) channel is consistent with a role in transepithelial Cl(−) secretion under control conditions, but it remains to be determined whether these Cl(−) channels also mediate transepithelial Cl(−) secretion under diuretic conditions in the presence of leucokinin.
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Affiliation(s)
- K R O'Connor
- Department of Biomedical Sciences, VRT 8014, Cornell University, Ithaca, NY 14853, USA
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17
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Fogerty FJ, Juang JL, Petersen J, Clark MJ, Hoffmann FM, Mosher DF. Dominant effects of the bcr-abl oncogene on Drosophila morphogenesis. Oncogene 1999; 18:219-32. [PMID: 9926937 DOI: 10.1038/sj.onc.1202239] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
We targeted expression of human/fly chimeric Bcr-Abl proteins to the developing central nervous system (CNS) and eye imaginal disc of Drosophila melanogaster. Neural expression of human/fly chimeric P210 Bcr-Abl or P185 Bcr-Abl rescued abl mutant flies from pupal lethality, indicating that P210 and P185 Bcr-Abl can substitute functionally for Drosophila Abl during axonogenesis. However, increased levels of neurally expressed P210 or P185 Bcr-Abl but not Drosophila Abl produced CNS defects and lethality. Expression of P210 or P185 in the eye imaginal disc produced a dominant rough eye phenotype that was dependent on dosage of the transgene. Drosophila Enabled, previously identified as a suppressor of the abl mutant phenotype and substrate for Drosophila Abl kinase, had markedly increased phosphotyrosine levels in Bcr-Abl expressing Drosophila, indicating that it is a substrate for Bcr-Abl as well. Drosophila, therefore, is a suitable model system to identify Bcr-Abl interactions important for signal transduction and oncogenesis.
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Affiliation(s)
- F J Fogerty
- Department of Medicine, University of Wisconsin Comprehensive Cancer Center, Madison 53706, USA
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Carlson SD, Hilgers SL. Perineurium in the Drosophila (Diptera : Drosophilidae) embryo and its role in the blood-brain/nerve barrier. ACTA ACUST UNITED AC 1998. [DOI: 10.1016/s0020-7322(98)00004-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Abstract
This paper reviews the structure and function of insect mechanoreceptors with respect to their cellular, subcellular, and cuticular organization. Four types are described and their function is discussed: 1, the bristles; 2, the trichobothria; 3, the campaniform sensilla; and 4, the scolopidia. Usually, bristles respond to touch, trichobothria to air currents and sound, campaniform sensilla to deformation of the cuticle, and scolopidia to stretch. Mechanoreceptors are composed of four cells: a bipolar sensory neuron, which is enveloped by the thecogen, the trichogen, and the tormogen cells. Apically, the neuron gives off a ciliary dendrite which is attached to the stimulus-transmitting cuticular structures. In types 1-3, the tip of the dendrite contains a highly organized cytoskeletal complex of microtubules, the "tubular body," which is connected to the dendritic membrane via short rods, the "membrane-integrated cones" (MICs). The dendritic membrane is attached to the cuticle via fine attachment fibers. The hair-type sensilla (types 1, 2) are constructed as first-order levers, which transmit deflection of the hair directly to the dendrite tip. In campaniform sensilla (type 3), there is a cuticular dome instead of a hair and the dendrite is stimulated by deformation of the cuticle. In these three types, a slight lateral compression of the dendrite tip is most probably the effective stimulus. In scolopidia, the dendritic membrane is most probably stimulated by stretch. On the subcellular level, connectors between the cytoskeleton, the dendritic membrane, and extracellular (cuticular) structures are present in all four types and are thought to be engaged in membrane depolarization.
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Affiliation(s)
- T A Keil
- Arbeitsgruppe Kaissling, Max-Planck-Institut für Verhaltensphysiologie, Seewiesen, Germany
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Abstract
Our understanding of epithelial development in Drosophila has been greatly improved in recent years. Two key regulators of epithelial polarity, Crumbs and DE-cadherin, have been studied at the genetic and molecular levels and a number of additional genes are being analyzed that contribute to the differentiation of epithelial cell structure. Epithelial architecture has a profound influence on morphogenetic movements, patterning and cell-type determination. The combination of embryological and genetic/molecular tools in Drosophila will help us to elucidate the complex events that determine epithelial cell structure and how they relate to morphogenesis and other developmental processes.
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Affiliation(s)
- U Tepass
- Department of Zoology, University of Toronto, Ontario, Canada.
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