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Györi J, Kohn AB, Romanova DY, Moroz LL. ATP signaling in the integrative neural center of Aplysia californica. Sci Rep 2021; 11:5478. [PMID: 33750901 PMCID: PMC7943599 DOI: 10.1038/s41598-021-84981-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Accepted: 02/23/2021] [Indexed: 11/22/2022] Open
Abstract
ATP and its ionotropic P2X receptors are components of the most ancient signaling system. However, little is known about the distribution and function of purinergic transmission in invertebrates. Here, we cloned, expressed, and pharmacologically characterized the P2X receptors in the sea slug Aplysia californica—a prominent neuroscience model. AcP2X receptors were successfully expressed in Xenopus oocytes and displayed activation by ATP with two-phased kinetics and Na+-dependence. Pharmacologically, they were different from other P2X receptors. The ATP analog, Bz-ATP, was a less effective agonist than ATP, and PPADS was a more potent inhibitor of the AcP2X receptors than the suramin. AcP2X were uniquely expressed within the cerebral F-cluster, the multifunctional integrative neurosecretory center. AcP2X receptors were also detected in the chemosensory structures and the early cleavage stages. Therefore, in molluscs, rapid ATP-dependent signaling can be implicated both in development and diverse homeostatic functions. Furthermore, this study illuminates novel cellular and systemic features of P2X-type ligand-gated ion channels for deciphering the evolution of neurotransmitters.
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Affiliation(s)
- János Györi
- Department of Experimental Zoology, Centre for Ecological Research, Balaton Limnological Institute, 8237, Tihany, Hungary.,Whitney Laboratory for Marine Bioscience, University of Florida, St. Augustine, FL, 32080, USA
| | - Andrea B Kohn
- Whitney Laboratory for Marine Bioscience, University of Florida, St. Augustine, FL, 32080, USA
| | - Daria Y Romanova
- Institute of Higher Nervous Activity and Neurophysiology of RAS, Moscow, 117485, Russia
| | - Leonid L Moroz
- Whitney Laboratory for Marine Bioscience, University of Florida, St. Augustine, FL, 32080, USA. .,Departments of Neuroscience and McKnight Brain Institute, University of Florida, Gainesville, FL, 32610, USA.
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2
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Application of Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry Imaging for Food Analysis. Foods 2019; 8:foods8120633. [PMID: 31810360 PMCID: PMC6963588 DOI: 10.3390/foods8120633] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Revised: 11/21/2019] [Accepted: 11/28/2019] [Indexed: 02/06/2023] Open
Abstract
Food contains various compounds, and there are many methods available to analyze each of these components. However, the large amounts of low-molecular-weight metabolites in food, such as amino acids, organic acids, vitamins, lipids, and toxins, make it difficult to analyze the spatial distribution of these molecules. Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) imaging is a two-dimensional ionization technology that allows the detection of small metabolites in tissue sections without requiring purification, extraction, separation, or labeling. The application of MALDI-MS imaging in food analysis improves the visualization of these compounds to identify not only the nutritional content but also the geographical origin of the food. In this review, we provide an overview of some recent applications of MALDI-MS imaging, demonstrating the advantages and prospects of this technology compared to conventional approaches. Further development and enhancement of MALDI-MS imaging is expected to offer great benefits to consumers, researchers, and food producers with respect to breeding improvement, traceability, the development of value-added foods, and improved safety assessments.
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3
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Localization and functional characterization of a novel adipokinetic hormone in the mollusk, Aplysia californica. PLoS One 2014; 9:e106014. [PMID: 25162698 PMCID: PMC4146582 DOI: 10.1371/journal.pone.0106014] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2014] [Accepted: 07/28/2014] [Indexed: 11/19/2022] Open
Abstract
Increasing evidence suggests that gonadotropin-releasing hormone (GnRH), corazonin, adipokinetic hormone (AKH), and red pigment-concentrating hormone all share common ancestry to form a GnRH superfamily. Despite the wide presence of these peptides in protostomes, their biological effects remain poorly characterized in many taxa. This study had three goals. First, we cloned the full-length sequence of a novel AKH, termed Aplysia-AKH, and examined its distribution in an opisthobranch mollusk, Aplysia californica. Second, we investigated in vivo biological effects of Aplysia-AKH. Lastly, we compared the effects of Aplysia-AKH to a related A. californica peptide, Aplysia-GnRH. Results suggest that Aplysia-AKH mRNA and peptide are localized exclusively in central tissues, with abdominal, cerebral, and pleural ganglia being the primary sites of Aplysia-AKH production. However, Aplysia-AKH-positive fibers were found in all central ganglia, suggesting diverse neuromodulatory roles. Injections of A. californica with Aplysia-AKH significantly inhibited feeding, reduced body mass, increased excretion of feces, and reduced gonadal mass and oocyte diameter. The in vivo effects of Aplysia-AKH differed substantially from Aplysia-GnRH. Overall, the distribution and biological effects of Aplysia-AKH suggest it has diverged functionally from Aplysia-GnRH over the course of evolution. Further, that both Aplysia-AKH and Aplysia-GnRH failed to activate reproduction suggest the critical role of GnRH as a reproductive activator may be a phenomenon unique to vertebrates.
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Zaima N, Goto-Inoue N, Moriyama T. Matrix-Assisted Laser Desorption/Ionization Imaging Mass Spectrometry: New Technology for Vascular Pathology. J Vasc Res 2014; 51:144-8. [DOI: 10.1159/000362123] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2013] [Accepted: 02/11/2014] [Indexed: 01/30/2023] Open
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TARGETED MASS spectrometry Imaging: Specific Targeting Mass Spectrometry imaging technologies from history to perspective. ACTA ACUST UNITED AC 2012; 47:133-74. [DOI: 10.1016/j.proghi.2012.08.002] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/27/2012] [Indexed: 12/28/2022]
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White SH, Magoski NS. Acetylcholine-evoked afterdischarge in Aplysia bag cell neurons. J Neurophysiol 2012; 107:2672-85. [DOI: 10.1152/jn.00745.2011] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
A brief synaptic input to the bag cell neurons of Aplysia evokes a lengthy afterdischarge and the secretion of peptide hormones that trigger ovulation. The input transmitter is unknown, although prior work has shown that afterdischarges are prevented by strychnine. Because molluscan excitatory cholinergic synapses are blocked by strychnine, we tested the hypothesis that acetylcholine acts on an ionotropic receptor to initiate the afterdischarge. In cultured bag cell neurons, acetylcholine induced a short burst of action potentials followed by either return to near baseline or, like a true afterdischarge, transition to continuous firing. The current underlying the acetylcholine-induced depolarization was dose dependent, associated with increased membrane conductance, and sensitive to the nicotinic antagonists hexamethonium, mecamylamine, and α-conotoxin ImI. Whereas nicotine, choline, carbachol, and glycine did not mimic acetylcholine, tetramethylammonium did produce a similar current. Consistent with an ionotropic receptor, the response was not altered by intracellular dialysis with the G protein blocker guanosine 5′-(β-thio)diphosphate. Recording from the intact bag cell neuron cluster showed acetylcholine to evoke prominent depolarization, which often led to extended bursting, but only in the presence of the acetylcholinesterase inhibitor neostigmine. Extracellular recording confirmed that exogenous acetylcholine caused genuine afterdischarges, which, as per those generated synaptically, rendered the cluster refractory to further stimulation. Finally, treatment with a combination of mecamylamine and α-conotoxin ImI blocked synaptically induced afterdischarges in the intact bag cell neuron cluster. Acetylcholine appears to elicit the afterdischarge through an ionotropic receptor. This represents an expedient means for transient stimulation to elicit prolonged firing in the absence of ongoing synaptic input.
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Affiliation(s)
- Sean H. White
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - Neil S. Magoski
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
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Boggio KJ, Obasuyi E, Sugino K, Nelson SB, Agar NY, Agar JN. Recent advances in single-cell MALDI mass spectrometry imaging and potential clinical impact. Expert Rev Proteomics 2012; 8:591-604. [PMID: 21999830 DOI: 10.1586/epr.11.53] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Single-cell analysis is gaining popularity in the field of mass spectrometry as a method for analyzing protein and peptide content in cells. The spatial resolution of MALDI mass spectrometry (MS) imaging is by a large extent limited by the laser focal diameter and the displacement of analytes during matrix deposition. Owing to recent advancements in both laser optics and matrix deposition methods, spatial resolution on the order of a single eukaryotic cell is now achievable by MALDI MS imaging. Provided adequate instrument sensitivity, a lateral resolution of approximately 10 µm is currently attainable with commercial instruments. As a result of these advances, MALDI MS imaging is poised to become a transformative clinical technology. In this article, the crucial steps needed to obtain single-cell resolution are discussed, as well as potential applications to disease research.
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Affiliation(s)
- Kristin J Boggio
- Department of Chemistry and Volen Center for Complex Systems, Brandeis University, Waltham, MA, USA
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HEYLAND ANDREAS, VUE ZER, VOOLSTRA CHRISTIANR, MEDINA MÓNICA, MOROZ LEONIDL. Developmental transcriptome of Aplysia californica. JOURNAL OF EXPERIMENTAL ZOOLOGY. PART B, MOLECULAR AND DEVELOPMENTAL EVOLUTION 2011; 316B:113-34. [PMID: 21328528 PMCID: PMC4028319 DOI: 10.1002/jez.b.21383] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2010] [Revised: 09/08/2010] [Accepted: 10/12/2010] [Indexed: 11/08/2022]
Abstract
Genome-wide transcriptional changes in development provide important insight into mechanisms underlying growth, differentiation, and patterning. However, such large-scale developmental studies have been limited to a few representatives of Ecdysozoans and Chordates. Here, we characterize transcriptomes of embryonic, larval, and metamorphic development in the marine mollusc Aplysia californica and reveal novel molecular components associated with life history transitions. Specifically, we identify more than 20 signal peptides, putative hormones, and transcription factors in association with early development and metamorphic stages-many of which seem to be evolutionarily conserved elements of signal transduction pathways. We also characterize genes related to biomineralization-a critical process of molluscan development. In summary, our experiment provides the first large-scale survey of gene expression in mollusc development, and complements previous studies on the regulatory mechanisms underlying body plan patterning and the formation of larval and juvenile structures. This study serves as a resource for further functional annotation of transcripts and genes in Aplysia, specifically and molluscs in general. A comparison of the Aplysia developmental transcriptome with similar studies in the zebra fish Danio rerio, the fruit fly Drosophila melanogaster, the nematode Caenorhabditis elegans, and other studies on molluscs suggests an overall highly divergent pattern of gene regulatory mechanisms that are likely a consequence of the different developmental modes of these organisms.
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Affiliation(s)
| | - ZER VUE
- University of California, Merced, School of Natural Sciences, Merced, California
| | - CHRISTIAN R. VOOLSTRA
- University of California, Merced, School of Natural Sciences, Merced, California
- Red Sea Research Center, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia
| | - MÓNICA MEDINA
- University of California, Merced, School of Natural Sciences, Merced, California
| | - LEONID L. MOROZ
- The Whitney Laboratory for Marine Bioscience, University of Florida, Florida
- Department of Neuroscience, University of Florida, Florida
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9
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Matrix-assisted laser desorption/ionization imaging mass spectrometry. Int J Mol Sci 2010; 11:5040-55. [PMID: 21614190 PMCID: PMC3100838 DOI: 10.3390/ijms11125040] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2010] [Revised: 11/25/2010] [Accepted: 11/27/2010] [Indexed: 12/24/2022] Open
Abstract
Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) is a powerful tool that enables the simultaneous detection and identification of biomolecules in analytes. MALDI-imaging mass spectrometry (MALDI-IMS) is a two-dimensional MALDI-mass spectrometric technique used to visualize the spatial distribution of biomolecules without extraction, purification, separation, or labeling of biological samples. MALDI-IMS has revealed the characteristic distribution of several biomolecules, including proteins, peptides, amino acids, lipids, carbohydrates, and nucleotides, in various tissues. The versatility of MALDI-IMS has opened a new frontier in several fields such as medicine, agriculture, biology, pharmacology, and pathology. MALDI-IMS has a great potential for discovery of unknown biomarkers. In this review, we describe the methodology and applications of MALDI-IMS for biological samples.
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10
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Moroz LL, Kohn AB. Do different neurons age differently? Direct genome-wide analysis of aging in single identified cholinergic neurons. Front Aging Neurosci 2010; 2. [PMID: 20725513 PMCID: PMC2910937 DOI: 10.3389/neuro.24.006.2010] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2009] [Accepted: 01/27/2010] [Indexed: 11/24/2022] Open
Abstract
Aplysia californica is a powerful experimental system to study the entire scope of genomic and epigenomic regulation at the resolution of single functionally characterized neurons and is an emerging model in the neurobiology of aging. First, we have identified and cloned a number of evolutionarily conserved genes that are age-related, including components of apoptosis and chromatin remodeling. Second, we performed gene expression profiling of different identified cholinergic neurons between young and aged animals. Our initial analysis indicates that two cholinergic neurons (R2 and LPl1) revealed highly differential genome-wide changes following aging suggesting that on the molecular scale different neurons indeed age differently. Each of the neurons tested has a unique subset of genes differentially expressed in older animals, and the majority of differently expressed genes (including those related to apoptosis and Alzheimer's disease) are found in aging neurons of one but not another type. The performed analysis allows us to implicate (i) cell specific changes in histones, (ii) DNA methylation and (iii) regional relocation of RNAs as key processes underlying age-related changes in neuronal functions and synaptic plasticity. These mechanisms can fine-tune the dynamics of long-term chromatin remodeling, or control weakening and the loss of synaptic connections in aging. At the same time our genomic tests revealed evolutionarily conserved gene clusters associated with aging (e.g., apoptosis-, telomere- and redox-dependent processes, insulin and estrogen signaling and water channels).
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Affiliation(s)
- Leonid L Moroz
- Department of Neuroscience, Evelyn F and William L. McKnight Brain Institute, University of Florida Gainesville, FL, USA
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11
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Affiliation(s)
- Kamila Chughtai
- FOM-Institute for Atomic and Molecular Physics, Science Park 104, 1098 XG Amsterdam, The Netherlands
| | - Ron M.A. Heeren
- FOM-Institute for Atomic and Molecular Physics, Science Park 104, 1098 XG Amsterdam, The Netherlands
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12
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Jackson SN, Woods AS. Direct profiling of tissue lipids by MALDI-TOFMS. J Chromatogr B Analyt Technol Biomed Life Sci 2009; 877:2822-9. [PMID: 19095508 PMCID: PMC2945280 DOI: 10.1016/j.jchromb.2008.11.033] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2008] [Revised: 11/17/2008] [Accepted: 11/20/2008] [Indexed: 11/20/2022]
Abstract
Advances in matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) have allowed for the direct analysis of biological molecules from tissue. Although most of the early studies of direct tissue profiling by MALDI-TOFMS have focused on proteins and peptides, analysis of lipids has increased dramatically in recent years. This review gives an overview of the factors to consider when analyzing lipids directly from tissue and some recent examples of the use of MALDI-TOFMS for the direct profiling of lipids in tissue.
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Affiliation(s)
| | - Amina S. Woods
- NIDA IRP, NIH, 333 Cassell Drive, Baltimore, MD 21224, United States
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13
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Franck J, Arafah K, Elayed M, Bonnel D, Vergara D, Jacquet A, Vinatier D, Wisztorski M, Day R, Fournier I, Salzet M. MALDI imaging mass spectrometry: state of the art technology in clinical proteomics. Mol Cell Proteomics 2009; 8:2023-33. [PMID: 19451175 DOI: 10.1074/mcp.r800016-mcp200] [Citation(s) in RCA: 140] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A decade after its inception, MALDI imaging mass spectrometry has become a unique technique in the proteomics arsenal for biomarker hunting in a variety of diseases. At this stage of development, it is important to ask whether we can consider this technique to be sufficiently developed for routine use in a clinical setting or an indispensable technology used in translational research. In this report, we consider the contributions of MALDI imaging mass spectrometry and profiling technologies to clinical studies. In addition, we outline new directions that are required to align these technologies with the objectives of clinical proteomics, including: 1) diagnosis based on profile signatures that complement histopathology, 2) early detection of disease, 3) selection of therapeutic combinations based on the individual patient's entire disease-specific protein network, 4) real time assessment of therapeutic efficacy and toxicity, 5) rational redirection of therapy based on changes in the diseased protein network that are associated with drug resistance, and 6) combinatorial therapy in which the signaling pathway itself is viewed as the target rather than any single "node" in the pathway.
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Affiliation(s)
- Julien Franck
- MALDI Imaging Team, Laboratoire de Neuroimmunologie des Annélides, IFR 147, CNR-FRE 2933, University of Lille1, 59655 Villeneuve d'Ascq, France
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14
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Rubakhin SS, Sweedler JV. Quantitative measurements of cell-cell signaling peptides with single-cell MALDI MS. Anal Chem 2008; 80:7128-36. [PMID: 18707135 PMCID: PMC2646760 DOI: 10.1021/ac8010389] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2008] [Accepted: 07/14/2008] [Indexed: 11/28/2022]
Abstract
Cell-to-cell signaling peptides play important roles in neurotransmission, neuromodulation, and hormonal signaling. Significant progress has been achieved in qualitative investigations of signaling peptides in the nervous system using single cell matrix-assisted laser desorption/ionization mass spectrometry. However, quantitative information about signaling peptides is difficult to obtain with this approach because only small amounts of analytes are available for analysis. Here we describe several methods for quantitative microanalysis of peptides in individual Aplysia californica neurons and small pieces of tissue. Stable isotope labeling with d0- and d4-succinic anhydride and iTRAQ reagents has been successfully adopted for relative quantitation of nanoliter volume samples containing the Aplysia insulin C beta peptide. Comparative analysis of the C beta peptide release site, the upper labial nerve, and its synthesis location, the F- and C-clusters, shows that the release site possesses almost three times more of this compound. The method of standard addition permits absolute quantitation of the physiologically active neuropeptide cerebrin from small structures, including nerves and neuronal clusters, in the femtomole range with a limit of detection of 19 fmol. The simplicity of these methods and the commercial availability of the reagents allow quantitative measurements from a variety of small-volume biological samples.
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Affiliation(s)
- Stanislav S. Rubakhin
- Department of Chemistry and the Beckman Institute, University of Illinois, Urbana, Illinois 61801
| | - Jonathan V. Sweedler
- Department of Chemistry and the Beckman Institute, University of Illinois, Urbana, Illinois 61801
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15
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Wisztorski M, Croix D, Macagno E, Fournier I, Salzet M. Molecular MALDI imaging: an emerging technology for neuroscience studies. Dev Neurobiol 2008; 68:845-58. [PMID: 18383549 DOI: 10.1002/dneu.20623] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Mass spectrometry (MS) has become an essential tool for the detection, identification, and characterization of the molecular components of biological processes, such as those responsible for the dynamic properties of the nervous system. Generally, the application of these powerful techniques requires the destruction of the specimen under study, but recent technological advances have made it possible to apply the matrix-assisted laser desorption/ionization (MALDI) MS technique directly to tissue sections. The major advantage of direct MALDI analysis is that it enables the acquisition of local molecular expression profiles, while maintaining the topographic integrity of the tissue and avoiding time-consuming extraction, purification, and separation steps, which have the potential for introducing artifacts. With automation and the ability to display complex spectral data using imaging software, it is now possible to create multiple 2D maps of selected biomolecules in register with tissue sections, a method now known as MALDI Imaging, or MSI (for Mass Spectrometry Imaging). This creates, for example, an opportunity to correlate functional states, determined a priori with live recording or imaging, with the corresponding molecular maps obtained at the time the tissue is frozen and analyzed with MSI. We review the increasing application of MALDI Imaging to the analysis of molecular distributions of proteins and peptides in nervous tissues of both vertebrates and invertebrates, focusing in particular on recent studies of neurodegenerative diseases and early efforts to implement assays of neuronal development.
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Affiliation(s)
- Maxence Wisztorski
- Equipe Imagerie MALDI, Cité Scientifique, Université des Sciences et Technologies de Lille, 59650 Villeneuve d'Ascq, France
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16
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Romanova EV, Rubakhin SS, Sweedler JV. One-step sampling, extraction, and storage protocol for peptidomics using dihydroxybenzoic Acid. Anal Chem 2008; 80:3379-86. [PMID: 18321135 DOI: 10.1021/ac7026047] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The isolation and extraction of natively occurring signaling peptides (SPs) from tissue is a critical first step in characterizing these peptides. Recent studies have outlined several approaches designed to preserve and extract SPs from tissue. Here, we demonstrate a surprisingly simple method to extract SPs from tissue samples, ranging from cell clusters to brain punches to intact brain regions, using a matrix often employed in matrix-assisted laser desorption/ionization mass spectrometry-2,5-dihydroxybenzoic acid (DHB). DHB allows for the effective extraction of endogenous peptides from tissue as well as long-term preservation of tissue samples and extracts. Using the mouse pituitary gland as a model, the extraction protocol effectively recovers 24 known and many additional putative peptides from individual samples. Peptide extracts stored in the DHB extraction media are stable for years without freezing. The approach is also effective for other neuronal tissues; the complement of neuropeptides in bag cell neuron clusters from the Aplysia central nervous system, the rat cerebellum, and rat dorsal striatum also have been examined. Advantages of this new extraction procedure are its technical simplicity, reproducibility, ease of remote preparation of samples, and long-term sample preservation without freezing.
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Affiliation(s)
- Elena V Romanova
- Department of Chemistry and the Beckman Institute, University of Illinois, 600 South Mathews Avenue 63-5, Urbana, Illinois 61801, USA
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17
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Rubakhin SS, Sweedler JV. Characterizing peptides in individual mammalian cells using mass spectrometry. Nat Protoc 2007; 2:1987-97. [PMID: 17703210 DOI: 10.1038/nprot.2007.277] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Cell-to-cell chemical signaling plays multiple roles in coordinating the activity of the functional elements of an organism, with these elements ranging from a three-neuron reflex circuit to the entire animal. In recent years, single-cell mass spectrometry (MS) has enabled the discovery of cell-to-cell signaling molecules from the nervous system of a number of invertebrates. We describe a protocol for analyzing individual cells from rat pituitary using matrix-assisted laser desorption/ionization MS. Each step in the sample preparation process, including cell stabilization, isolation, sample preparation, signal acquisition and data interpretation, is detailed here. Although we employ this method to investigate peptides in individual pituitary cells, it can be adapted to other cell types and even subcellular sections from a range of animals. This protocol allows one to obtain 20-30 individual cell samples and acquire mass spectra from them in a single day.
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Affiliation(s)
- Stanislav S Rubakhin
- Department of Chemistry and the Beckman Institute, University of Illinois, Urbana, Illinois 61801, USA
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18
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Ye X, Kim WS, Rubakhin SS, Sweedler JV. Ubiquitous presence of argininosuccinate at millimolar levels in the central nervous system of Aplysia californica. J Neurochem 2006; 101:632-40. [PMID: 17250653 DOI: 10.1111/j.1471-4159.2006.04395.x] [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: 11/30/2022]
Abstract
Endogenous nitric oxide (NO) is generated by nitric oxide synthases (NOSs), which convert arginine (Arg) and oxygen to citrulline (Cit) and NO. Cit can be enzymatically transformed back to Arg by argininosuccinate synthetase (ASS) and argininosuccinate lyase (ASL) via a pathway involving argininosuccinate (ArgSuc). Arg, Cit, and ArgSuc levels have been measured in single neurons, neuronal clusters, and neuropil from the nervous system of the common neurobiological model Aplysia californica. Using capillary electrophoresis with laser-induced fluorescence detection, ArgSuc was found to be present in the nervous system in millimolar concentrations at levels significantly exceeding Cit levels (p<0.01). ArgSuc levels are proportional to Arg concentrations in single neurons, whereas they have no clear correlation to the Cit or Arg/Cit ratio. NOS-expressing neurons often exhibit fixative-resistant nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) staining. Incubation of ganglia with Arg results in an increase in Cit and ArgSuc levels in the NADPH-d-positive neuropil with no effect on ArgSuc levels in NADPH-d-negative neurons, suggesting NOS activity in the neuropil. Similar incubation with Cit leads to decreased ArgSuc levels in NADPH-d-negative neurons. These results can be explained by localization of NOS and ASS in different neurons; therefore, the complete Arg-Cit-NO cycle may not be present in the same neuron. The surprisingly high intracellular ArgSuc concentration suggests alternative sources of ArgSuc and that at least a portion may be formed by the reverse reaction of ASL (catalyzing the conversion of Arg to ArgSuc), which can be inhibited by Cit.
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Affiliation(s)
- Xiaoying Ye
- Department of Chemistry and the Beckman Institute, University of Illinois, Urbana, Illinois 61801, USA
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19
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Heyland A, Price DA, Bodnarova-Buganova M, Moroz LL. Thyroid hormone metabolism and peroxidase function in two non-chordate animals. JOURNAL OF EXPERIMENTAL ZOOLOGY. PART B, MOLECULAR AND DEVELOPMENTAL EVOLUTION 2006; 306:551-66. [PMID: 16739141 DOI: 10.1002/jez.b.21113] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
In mammals, thyroid hormone (TH) signaling is essential for metabolic control, differentiation and homeostasis. These hormones are also involved in the regulation of metamorphosis in amphibians and lampreys and a role in basal chordates has been suggested. Increasing evidence supports TH-related function not only in basal chordates such as urochordates and cephalochordates but also in other invertebrate groups. However, the regulatory mechanisms underlying TH function including the mechanisms of endogenous synthesis of hormones in these groups are essentially unknown. Our data provide evidence for endogenous TH synthesis in the sea hare Aplysia californica and the sea urchin Lytechinus variegatus based on thin layer chromatography. Pharmacological experiments show that these hormones accelerate development to metamorphosis and specifically affect the formation of juvenile skeletal structures in the sea urchin. Furthermore, we identified two new peroxidase genes (LvTPO from L. variegatus and AcaTPO from A. californica) showing high sequence similarity with peroxidasin and thyroid peroxidases (the critical TH synthesis enzymes found in all vertebrates). Spatial and temporal expression patterns of these transcripts suggest a role of LvTPO and AcaTPO in a variety of processes such as development to metamorphosis and the regulation of the animal's energetics. We discuss our new findings in the context of evolution of TH synthesis and TH signaling in non-chordate animals.
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Affiliation(s)
- Andreas Heyland
- The Whitney Laboratory for Marine Bioscience, University of Florida, St Augustine, FL 32080, USA.
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20
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Woods AS, Jackson SN. Brain tissue lipidomics: direct probing using matrix-assisted laser desorption/ionization mass spectrometry. AAPS JOURNAL 2006. [PMID: 16796390 DOI: 10.1208/aapsj080244] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Lipidomics is the new frontier in biomolecular structural studies. Not only are lipids the main components in membranes that define the contours of the cell and its organelles, but they are also used for storage. Lipids form stable noncovalent complexes with proteins as well as with many drugs. Lipids are a storage depot for drugs and certain types of organic molecules. To study lipid composition and distribution, complex and time-consuming techniques are used. However, recent advances in mass spectrometry, mainly matrix-assisted laser desorption/ionization (MALDI) have made it possible to directly probe tissues to study structural components, as well as for the localization of drugs. Direct tissue imaging is a powerful tool as it gives a more complete and accurate structural picture and can trace and follow where drugs localize in tissue with minimal anatomical disruption and a minimum of manipulations. Hence, we believe that in addition to its accuracy and efficiency, this new approach will lead to a better understanding of physiological processes as well as the pathophysiology of disease.
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Affiliation(s)
- Amina S Woods
- National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, 5500 Nathan Shock Drive, Baltimore, MD 21224, USA.
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21
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Woods AS, Jackson SN. Brain tissue lipidomics: direct probing using matrix-assisted laser desorption/ionization mass spectrometry. AAPS JOURNAL 2006; 8:E391-5. [PMID: 16796390 PMCID: PMC3231574 DOI: 10.1007/bf02854910] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Lipidomics is the new frontier in biomolecular structural studies. Not only are lipids the main components in membranes that define the contours of the cell and its organelles, but they are also used for storage. Lipids form stable noncovalent complexes with proteins as well as with many drugs. Lipids are a storage depot for drugs and certain types of organic molecules. To study lipid composition and distribution, complex and time-consuming techniques are used. However, recent advances in mass spectrometry, mainly matrix-assisted laser desorption/ionization (MALDI) have made it possible to directly probe tissues to study structural components, as well as for the localization of drugs. Direct tissue imaging is a powerful tool as it gives a more complete and accurate structural picture and can trace and follow where drugs localize in tissue with minimal anatomical disruption and a minimum of manipulations. Hence, we believe that in addition to its accuracy and efficiency, this new approach will lead to a better understanding of physiological processes as well as the pathophysiology of disease.
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Affiliation(s)
- Amina S Woods
- National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, 5500 Nathan Shock Drive, Baltimore, MD 21224, USA.
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22
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Miao H, Rubakhin SS, Scanlan CR, Wang L, Sweedler JV. d-Aspartate as a putative cell-cell signaling molecule in theAplysia californicacentral nervous system. J Neurochem 2006; 97:595-606. [PMID: 16539650 DOI: 10.1111/j.1471-4159.2006.03791.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
The content, synthesis and transport of D-aspartate (D-Asp) in the CNS of Aplysia californica is investigated using capillary electrophoresis (CE) with both laser-induced fluorescence and radionuclide detection. Millimolar concentrations of D-Asp are found in various regions of the CNS. In the cerebral ganglion, three adjacent neuronal clusters have reproducibly different D-Asp levels; for example, in the F- and C-clusters, up to 85% of the free Asp is present in the D-form. Heterogeneous distribution of D-Asp is also found in the individual identified neurons tested, including the optical ganglion top-layer neurons, metacerebral cells, R2 neurons, and F-, C- and G-cluster neurons. The F-cluster neurons have the highest percentage of D-Asp (approximately 58% of the total Asp), whereas the lowest value of approximately 8% is found in R2 neurons. In pulse-chase experiments with radiolabeled D-Asp, followed by CE with radionuclide detection, the synthesis of D-Asp from L-aspartate (L-Asp) is confirmed. Is D-Asp in the soma, or is it transported to distantly located release sites? D-Asp is clearly detected in the major nerves of A. californica, including the pleuroabdominal and cerebrobuccal connectives and the anterior tentacular nerves, suggesting it is transported long distances. In addition, both D-Asp and L-Asp are transported in the pleuroabdominal connectives in a colchicine-dependent manner, whereas several other amino acids are not. Finally, d-Asp produces electrophysiological effects similar to those induced by L-Asp. These data are consistent with an active role for D-Asp in cell-to-cell communication.
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Affiliation(s)
- Hai Miao
- Department of Chemistry and the Beckman Institute, University of Illinois at Urbana-Champaign, 61801, USA
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23
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Hummon AB, Amare A, Sweedler JV. Discovering new invertebrate neuropeptides using mass spectrometry. MASS SPECTROMETRY REVIEWS 2006; 25:77-98. [PMID: 15937922 DOI: 10.1002/mas.20055] [Citation(s) in RCA: 127] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Neuropeptides are a complex set of messenger molecules controlling a wide array of regulatory functions and behaviors within an organism. These neuromodulators are cleaved from longer protein molecules and often experience numerous post-translational modifications to achieve their bioactive form. As a result of this complexity, sensitive and versatile analysis schemes are needed to characterize neuropeptides. Mass spectrometry (MS) through a variety of approaches has fueled the discovery of hundreds of neuropeptides in invertebrate species in the last decade. Particularly successful are direct tissue and single neuron analyses by matrix-assisted laser desorption/ionization (MALDI) MS, which has been used to elucidate approximately 440 neuropeptides, and examination of neuronal homogenates by electrospray ionization techniques (ESI), also leading to the characterization of over 450 peptides. Additional MS methods with great promise for the discovery of neuropeptides are MS imaging and large-scale peptidomics studies in combination with a sequenced genome.
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Affiliation(s)
- Amanda B Hummon
- Department of Chemistry, University of Illinois, Urbana, Illinois 61801, USA
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Jezzini SH, Moroz LL. Identification and distribution of a two-pore domain potassium channel in the CNS of Aplysia californica. ACTA ACUST UNITED AC 2004; 127:27-38. [PMID: 15306118 DOI: 10.1016/j.molbrainres.2004.05.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/01/2004] [Indexed: 11/26/2022]
Abstract
A cDNA encoding a potassium channel of the two-pore domain family (K2p) of leak channels was cloned from the CNS of the marine opisthobranch Aplysia californica. This is the first sequence of the K2p family identified in molluscs and has been named AcK2p1. The deduced amino acid sequence is homologous to channels of the mammalian two-pore domain halothane inhibited (THIK) subfamily, bearing 46% identity to THIK-1 (KCNK 13) and 48% to THIK-2 (KCNK12). We used in-situ hybridization to analyze the distribution of this class of channels in the CNS. AcK2p1 is specifically expressed in many central neurons of all major ganglia including the largest identified neurons MCC, R2 and LP1. The highest expression of AcK2p1 was detected in an asymmetrical and distinct cluster of up to 30 cells located at the dorsal-medial region of the right pleural ganglion. The neuron-specific distribution seen in the molluscan CNS is consistent with data from mammals that indicate THIK is only expressed in restricted neuronal populations, suggesting its involvement in both the maintenance of neuronal phenotype and in the specific functional role of these neurons in their respective networks.
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Affiliation(s)
- Sami H Jezzini
- The Whitney Laboratory and Department of Neuroscience, University of Florida, 9505 Ocean Shore Blvd. St. Augustine, FL 32080, USA
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Romanova EV, Fosser KA, Rubakhin SS, Nuzzo RG, Sweedler JV. Engineering the morphology and electrophysiological parameters of cultured neurons by microfluidic surface patterning. FASEB J 2004; 18:1267-9. [PMID: 15208266 DOI: 10.1096/fj.03-1368fje] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The ability to control the orientation, morphology, and electrophysiological characteristics of neurons in culture allows the construction of neural circuits with defined physiological properties. Using microfluidic protein deposition onto chemically modified glass, we achieve the controlled growth of Aplysia neurons on geometrical patterns of poly-L-lysine and collagen IV, surrounded by nonadhesive regions of bovine albumin. We investigate the parameters essential for forming functional neuronal networks, the morphology, biochemistry, and electrophysiology under engineered cell culture conditions. We demonstrate that not only the orientation of neurite extension but also the number of primary neurites originating from the cell soma, their length, and branching pattern depend on the spatial constraints presented by the size and shape of the adhesion region on the patterned substrate. In addition, the physicochemical properties of the support layer influence the electrical activity of the cultured neurons. Substrate-dependent changes in the amplitude and in the dynamic parameters of the action potential cause decreased spike broadening in patterned neurons, which reflects changes in the number or functioning of active membrane ion channels. In contrast to morphology and electrophysiology, the neuropeptide content, as determined by mass spectrometry of individual patterned neurons, is not affected by the growth on patterned surfaces. Our results suggest that the morphological and electrophysiological parameters of neurons can be predictably altered/engineered by modulation of the chemical, physical, and topographical features of culture substrates. We also demonstrate that a full suite of techniques is required for functional characterization of neurons on engineered substrates.
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Affiliation(s)
- Elena V Romanova
- Department of Chemistry, Beckman Institute and Frederick Seitz Materials Research Laboratory, University of Illinois, Urbana, Illinois, USA
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26
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Dombeck DA, Blanchard-Desce M, Webb WW. Optical recording of action potentials with second-harmonic generation microscopy. J Neurosci 2004; 24:999-1003. [PMID: 14749445 PMCID: PMC6729824 DOI: 10.1523/jneurosci.4840-03.2004] [Citation(s) in RCA: 127] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Nonlinear microscopy has proven to be essential for neuroscience investigations of thick tissue preparations. However, the optical recording of fast (approximately 1 msec) cellular electrical activity has never until now been successfully combined with this imaging modality. Through the use of second-harmonic generation microscopy of primary Aplysia neurons in culture labeled with 4-[4-(dihexylamino)phenyl][ethynyl]-1-(4-sulfobutyl)pyridinium (inner salt), we optically recorded action potentials with 0.833 msec temporal and 0.6 microm spatial resolution on soma and neurite membranes. Second-harmonic generation response as a function of change in membrane potential was found to be linear with a signal change of approximately 6%/100 mV. The signal-to-noise ratio was approximately 1 for single-trace action potential recordings but was readily increased to approximately 6-7 with temporal averaging of approximately 50 scans. Photodamage was determined to be negligible by observing action potential characteristics, cellular resting potential, and gross cellular morphology during and after laser illumination. High-resolution (micrometer scale) optical recording of membrane potential activity by previous techniques has been limited to imaging depths an order of magnitude less than nonlinear methods. Because second-harmonic generation is capable of imaging up to approximately 400 microm deep into intact tissue with submicron resolution and little out-of-focus photodamage or bleaching, its ability to record fast electrical activity should prove valuable to future electrophysiology studies.
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Affiliation(s)
- Daniel A Dombeck
- School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853, USA
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Rubakhin SS, Greenough WT, Sweedler JV. Spatial Profiling with MALDI MS: Distribution of Neuropeptides within Single Neurons. Anal Chem 2003; 75:5374-80. [PMID: 14710814 DOI: 10.1021/ac034498+] [Citation(s) in RCA: 125] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
MALDI MS imaging and single-cell profiling are important new capabilities for mass spectrometry. The distribution of neuropeptides within a cell plays an important role in the functioning of the cells in a neuronal network. Protocols for subcellular MALDI MS are described that allow comparative peptide profiling of cell bodies and the neuronal processes (neurites) using single isolated neurons from the neuronal model Aplysia californica. The seawater surrounding the neurons is problematic for mass spectrometry and so must be removed in a manner that does not cause morphological changes or a redistribution of the neuropeptides. Several protocols have been investigated for subcellular spatial profiling, including the use of air-drying, replacement of the seawater with deionized water, and substitution of the cell matrix with fluorinert, mineral oil and glycerol, as well as paraformaldehyde fixation. Glycerol stabilization offers the best combination of preservation of cell morphology and prevention of neuropeptide redistribution. The profiles of the peptides in specific neuronal processes and the cell bodies demonstrate a variety of differences that appear to be cell-specific. These methods are suitable for smaller cells and subcellular MS imaging.
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Affiliation(s)
- Stanislav S Rubakhin
- Department of Chemistry, Psychology and the Beckman Institute, University of Illinois, Urbana, Illinois 61801, USA
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Kruse R, Sweedler JV. Spatial profiling invertebrate ganglia using MALDI MS. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2003; 14:752-759. [PMID: 12837597 DOI: 10.1016/s1044-0305(03)00288-5] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The ability of MALDI TOF MS to spatially map peptides and proteins directly from a tissue is an exciting advance to imaging mass spectrometry. Recent advances in instrumentation for MS have resulted in instruments capable of achieving several micron spatial resolution while acquiring high-resolution mass spectra. Currently, the ability to obtain high quality mass spectrometric images depends on sample preparation protocols that often result in limited spatial resolution. A number of sample preparation and matrix deposition protocols are evaluated for spatial profiling of Aplysia californica exocrine gland and neuronal tissues. Such samples are different from mammalian tissues, but make good targets for method optimization because of the wealth of biochemical information available on neuropeptide processing and distribution. Electrospray matrix deposition and a variety of freezing methods have been found to be optimum for these invertebrate tissues, with the exact protocols being tissue dependent.
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Affiliation(s)
- Rebecca Kruse
- Department of Chemistry and the Beckman Institute, University of Illinois, Urbana, Illinois 61801, USA
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Identification and characterization of the feeding circuit-activating peptides, a novel neuropeptide family of aplysia. J Neurosci 2002. [PMID: 12196603 DOI: 10.1523/jneurosci.22-17-07797.2002] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
We use a multidisciplinary approach to identify, map, and characterize the bioactivity of modulatory neuropeptides in the circuitry that generates feeding behavior in Aplysia. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry of the cerebral-buccal connective (CBC), a nerve containing axons of many interneurons that control feeding behavior of Aplysia, was used to identify neuropeptides that may participate in generation and shaping of feeding motor programs. Using this functionally oriented search, we identified a novel family of peptides that we call the feeding circuit-activating peptides (FCAPs). Two peptides with masses identical to those observed in the CBCs (molecular weight 1387 and 1433) were purified from buccal ganglia and partially sequenced using mass spectrometry. The amino acid sequence was then used to clone the FCAP precursor, which encodes multiple copies of eight different FCAPs. The two FCAPs present in highest copy number correspond to those observed in the CBC. The distribution of FCAP expression was mapped using Northern analysis, whole-mount in situ hybridization, and immunocytochemistry. Consistent with our initial findings, FCAP-immunopositive axons were observed in the CBC. Furthermore, we found that FCAP was present in some cerebral-buccal and buccal-cerebral interneurons. As their name suggests, FCAPs are capable of initiating rhythmic feeding motor programs and are the first neuropeptides with such activity in this circuit. The actions of FCAPs suggest that these peptides may contribute to the induction and maintenance of food-induced arousal. FCAPs were also localized to several other neuronal systems, suggesting that FCAPs may play a role in the regulation of multiple behaviors.
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Li L, Floyd PD, Rubakhin SS, Romanova EV, Jing J, Alexeeva VY, Dembrow NC, Weiss KR, Vilim FS, Sweedler JV. Cerebrin prohormone processing, distribution and action in Aplysia californica. J Neurochem 2001; 77:1569-80. [PMID: 11413240 DOI: 10.1046/j.1471-4159.2001.00360.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The isolation, characterization, and bioactivity in the feeding circuitry of a novel neuropeptide in the Aplysia californica central nervous system are reported. The 17-residue amidated peptide, NGGTADALYNLPDLEKIamide, has been termed cerebrin due to its primary location in the cerebral ganglion. Liquid chromatographic purification guided by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry allowed the isolation of the peptide with purity adequate for Edman sequencing. The cerebrin cDNA has been characterized and encodes an 86 amino acid prohormone that predicts cerebrin and one additional peptide. Mapping using in situ hybridization and immunocytochemistry showed that cerebrin containing neuronal somata are localized almost exclusively in the cerebral ganglion, mostly in the F- and C-clusters. Both immunostaining and mass spectrometry demonstrated the presence of cerebrin in the neurohemal region of the upper labial nerve. In addition, immunoreactive processes were detected in the neuropil of all of the ganglia, including the buccal ganglia, and in some interganglionic connectives, including the cerebral-buccal connective. This suggests that cerebrin may also function as a local signaling molecule. Cerebrin has a profound effect on the feeding motor pattern elicited by the command-like neuron CBI-2, dramatically shortening the duration of the radula protraction in a concentration-dependent manner, mimicking the motor-pattern alterations observed in food induced arousal states. These findings suggest that cerebrin may contribute to food-induced arousal in the animal. Cerebrin-like immunoreactivity is also present in Lymnaea stagnalis suggesting that cerebrin-like peptides may be widespread throughout gastropoda.
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Affiliation(s)
- L Li
- Department of Chemistry and the Beckman Institute, University of Illinois, Urbana, Illinois 61801, USA
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Abstract
Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) has become a powerful and widespread analytical tool in all fields of life science. The wide mass range (1-300 kDa), high accuracy, and sensitivity make it a superior method for analysis of all kinds of biomolecules including proteins, nucleic acids, and carbohydrates. In combination with 2D-gelelectrophoresis, MALDI-TOF-MS is particularly suitable for the identification of protein spots via mass fingerprint or microsequencing. Furthermore, the method allows a detailed analysis of posttranslational protein modifications. Recently, the method was also successfully applied to DNA sequencing as well as screening for mutations. Thus, high-throughput genotyping of single nucleotide polymorphisms has the potential to become a routine method for both laboratory and clinical applications.
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Affiliation(s)
- T Bonk
- Institute of Biochemistry, University of Erlangen-Nürnberg, Fahrstrasse 17, D-91054 Erlangen, Germany
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32
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Abstract
Matrix-assisted laser desorption-ionization (MALDI) mass spectrometry (MS) is a rapid and sensitive analytical approach that is well suited for obtaining molecular weights of peptides and proteins from complex samples. MALDI-MS can profile the peptides and proteins from single-cell and small tissue samples without the need for extensive sample preparation, except for the cell isolation and matrix application. Strategies for peptide identification and characterization of post-translational modifications are presented. Furthermore, several recent enhancements in MALDI-MS technology, including in situ peptide sequencing as well as the direct spatial mapping of peptides in cells and tissues are discussed.
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Affiliation(s)
- L Li
- Department of Chemistry and Beckman Institute, University of Illinois, Urbana, IL 61801, USA
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Abstract
The first Aplysia californica insulin gene is characterized and its proteolytic processing from prohormone to final peptides elucidated using a combination of biochemical and mass spectrometric methods. Aplysia insulin (AI) is one of the largest insulins found, with a molecular weight of 9146 Da, and an extended A chain compared with other invertebrate and vertebrate insulins. The AI prohormone produces a series of C peptides and also a unique N-terminally acetylated D peptide. AI-producing cells are restricted to the central region of the cerebral ganglia mostly within the F and C clusters, and AI is transported to neurohemal release sites located on the upper labial and anterior tentacular nerves. The expression of AI mRNA decreases when the animal is deprived of food, and injections of AI reduce hemolymph glucose levels, suggesting that the function of insulin-regulating metabolism has been conserved.
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