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Boto T, Tomchik SM. Functional Imaging of Learning-Induced Plasticity in the Central Nervous System with Genetically Encoded Reporters in Drosophila. Cold Spring Harb Protoc 2024; 2024:pdb.top107799. [PMID: 37197830 DOI: 10.1101/pdb.top107799] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Learning and memory allow animals to adjust their behavior based on the predictive value of their past experiences. Memories often exist in complex representations, spread across numerous cells and synapses in the brain. Studying relatively simple forms of memory provides insights into the fundamental processes that underlie multiple forms of memory. Associative learning occurs when an animal learns the relationship between two previously unrelated sensory stimuli, such as when a hungry animal learns that a particular odor is followed by a tasty reward. Drosophila is a particularly powerful model to study how this type of memory works. The fundamental principles are widely shared among animals, and there is a wide range of genetic tools available to study circuit function in flies. In addition, the olfactory structures that mediate associative learning in flies, such as the mushroom body and its associated neurons, are anatomically organized, relatively well-characterized, and readily accessible to imaging. Here, we review the olfactory anatomy and physiology of the olfactory system, describe how plasticity in the olfactory pathway mediates learning and memory, and explain the general principles underlying calcium imaging approaches.
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Affiliation(s)
- Tamara Boto
- Department of Physiology, Trinity College Dublin, Dublin 2, Ireland
- Trinity College Institute of Neuroscience, Trinity College Dublin, Dublin 2, Ireland
| | - Seth M Tomchik
- Neuroscience and Pharmacology, University of Iowa Carver College of Medicine, Iowa City, Iowa 52242, USA
- Stead Family Department of Pediatrics, University of Iowa Carver College of Medicine, Iowa City, Iowa 52242, USA
- Iowa Neuroscience Institute, University of Iowa Carver College of Medicine, Iowa City, Iowa 52242, USA
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2
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Aragon MJ, Mok AT, Shea J, Wang M, Kim H, Barkdull N, Xu C, Yapici N. Multiphoton imaging of neural structure and activity in Drosophila through the intact cuticle. eLife 2022; 11:e69094. [PMID: 35073257 PMCID: PMC8846588 DOI: 10.7554/elife.69094] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2021] [Accepted: 01/23/2022] [Indexed: 11/13/2022] Open
Abstract
We developed a multiphoton imaging method to capture neural structure and activity in behaving flies through the intact cuticle. Our measurements showed that the fly head cuticle has surprisingly high transmission at wavelengths >900nm, and the difficulty of through-cuticle imaging is due to the air sacs and/or fat tissue underneath the head cuticle. By compressing or removing the air sacs, we performed multiphoton imaging of the fly brain through the intact cuticle. Our anatomical and functional imaging results show that 2- and 3-photon imaging are comparable in superficial regions such as the mushroom body, but 3-photon imaging is superior in deeper regions such as the central complex and beyond. We further demonstrated 2-photon through-cuticle functional imaging of odor-evoked calcium responses from the mushroom body γ-lobes in behaving flies short term and long term. The through-cuticle imaging method developed here extends the time limits of in vivo imaging in flies and opens new ways to capture neural structure and activity from the fly brain.
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Affiliation(s)
- Max Jameson Aragon
- Department of Neurobiology and Behavior, Cornell UniversityIthacaUnited States
| | - Aaron T Mok
- School of Applied and Engineering Physics, Cornell UniversityIthacaUnited States
| | - Jamien Shea
- Department of Neurobiology and Behavior, Cornell UniversityIthacaUnited States
| | - Mengran Wang
- School of Applied and Engineering Physics, Cornell UniversityIthacaUnited States
| | - Haein Kim
- Department of Neurobiology and Behavior, Cornell UniversityIthacaUnited States
| | - Nathan Barkdull
- Department of Physics, University of FloridaGainesvilleUnited States
| | - Chris Xu
- School of Applied and Engineering Physics, Cornell UniversityIthacaUnited States
| | - Nilay Yapici
- Department of Neurobiology and Behavior, Cornell UniversityIthacaUnited States
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Valle AF, Honnef R, Seelig JD. Automated long-term two-photon imaging in head-fixed walking Drosophila. J Neurosci Methods 2021; 368:109432. [PMID: 34861285 DOI: 10.1016/j.jneumeth.2021.109432] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Revised: 11/24/2021] [Accepted: 11/26/2021] [Indexed: 10/19/2022]
Abstract
BACKGROUND The brain of Drosophila shows dynamics at multiple timescales, from the millisecond range of fast voltage or calcium transients to functional and structural changes occurring over multiple days. To relate such dynamics to behavior requires monitoring neural circuits across these multiple timescales in behaving animals. NEW METHOD Here, we develop a technique for automated long-term two-photon imaging in fruit flies, during wakefulness and extended bouts of immobility, as typically observed during sleep, navigating in virtual reality over up to seven days. The method is enabled by laser surgery, a microrobotic arm for controlling forceps for dissection assistance, an automated feeding robot, as well as volumetric, simultaneous multiplane imaging. RESULTS The approach is validated in the fly's head direction system and walking behavior as well a neural activity are recorded. The head direction system tracks the fly's walking direction over multiple days. COMPARISON WITH EXISTING METHODS In comparison with previous head-fixed preparations, the time span over which tethered behavior and neural activity can be recorded at the same time is extended from hours to days. Additionally, the reproducibility and ease of dissections are improved compared with manual approaches. Different from previous laser surgery approaches, only continuous wave lasers are required. Lastly, an automated feeding system allows continuously maintaining the fly for several days in the virtual reality setup without user intervention. CONCLUSIONS Imaging in behaving flies over multiple timescales will be useful for understanding circadian activity, learning and long-term memory, or sleep.
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Affiliation(s)
| | - Rolf Honnef
- Center of Advanced European Studies and Research (caesar), Bonn, Germany
| | - Johannes D Seelig
- Center of Advanced European Studies and Research (caesar), Bonn, Germany.
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Krasitskaya VV, Bashmakova EE, Frank LA. Coelenterazine-Dependent Luciferases as a Powerful Analytical Tool for Research and Biomedical Applications. Int J Mol Sci 2020; 21:E7465. [PMID: 33050422 PMCID: PMC7590018 DOI: 10.3390/ijms21207465] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Revised: 10/05/2020] [Accepted: 10/07/2020] [Indexed: 12/19/2022] Open
Abstract
: The functioning of bioluminescent systems in most of the known marine organisms is based on the oxidation reaction of the same substrate-coelenterazine (CTZ), catalyzed by luciferase. Despite the diversity in structures and the functioning mechanisms, these enzymes can be united into a common group called CTZ-dependent luciferases. Among these, there are two sharply different types of the system organization-Ca2+-regulated photoproteins and luciferases themselves that function in accordance with the classical enzyme-substrate kinetics. Along with deep and comprehensive fundamental research on these systems, approaches and methods of their practical use as highly sensitive reporters in analytics have been developed. The research aiming at the creation of artificial luciferases and synthetic CTZ analogues with new unique properties has led to the development of new experimental analytical methods based on them. The commercial availability of many ready-to-use assay systems based on CTZ-dependent luciferases is also important when choosing them by first-time-users. The development of analytical methods based on these bioluminescent systems is currently booming. The bioluminescent systems under consideration were successfully applied in various biological research areas, which confirms them to be a powerful analytical tool. In this review, we consider the main directions, results, and achievements in research involving these luciferases.
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Affiliation(s)
- Vasilisa V. Krasitskaya
- Institute of Biophysics SB RAS, Federal Research Center “Krasnoyarsk Science Center SB RAS”, 660036 Krasnoyarsk, Russia; (V.V.K.); (E.E.B.)
| | - Eugenia E. Bashmakova
- Institute of Biophysics SB RAS, Federal Research Center “Krasnoyarsk Science Center SB RAS”, 660036 Krasnoyarsk, Russia; (V.V.K.); (E.E.B.)
| | - Ludmila A. Frank
- Institute of Biophysics SB RAS, Federal Research Center “Krasnoyarsk Science Center SB RAS”, 660036 Krasnoyarsk, Russia; (V.V.K.); (E.E.B.)
- School of Fundamental Biology and Biotechnology, Siberian Federal University, 660041 Krasnoyarsk, Russia
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A single pair of leucokinin neurons are modulated by feeding state and regulate sleep-metabolism interactions. PLoS Biol 2019; 17:e2006409. [PMID: 30759083 PMCID: PMC6391015 DOI: 10.1371/journal.pbio.2006409] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Revised: 02/26/2019] [Accepted: 01/25/2019] [Indexed: 12/25/2022] Open
Abstract
Dysregulation of sleep and feeding has widespread health consequences. Despite extensive epidemiological evidence for interactions between sleep and metabolic function, little is known about the neural or molecular basis underlying the integration of these processes. D. melanogaster potently suppress sleep in response to starvation, and powerful genetic tools allow for mechanistic investigation of sleep–metabolism interactions. We have previously identified neurons expressing the neuropeptide leucokinin (Lk) as being required for starvation-mediated changes in sleep. Here, we demonstrate an essential role for Lk neuropeptide in metabolic regulation of sleep. The activity of Lk neurons is modulated by feeding, with reduced activity in response to glucose and increased activity under starvation conditions. Both genetic silencing and laser-mediated microablation localize Lk-dependent sleep regulation to a single pair of Lk neurons within the Lateral Horn (LHLK neurons). A targeted screen identified a role for 5′ adenosine monophosphate-activated protein kinase (AMPK) in starvation-modulated changes in sleep. Knockdown of AMPK in Lk neurons suppresses sleep and increases LHLK neuron activity in fed flies, phenocopying the starvation state. Further, we find a requirement for the Lk receptor in the insulin-producing cells (IPCs), suggesting LHLK–IPC connectivity is critical for sleep regulation under starved conditions. Taken together, these findings localize feeding-state–dependent regulation of sleep to a single pair of neurons within the fruit fly brain and provide a system for investigating the cellular basis of sleep–metabolism interactions. Neural regulation of sleep and feeding are interconnected and are critical for survival. Many animals reduce their sleep in response to starvation, presumably to forage for food. Here, we find that in the fruit fly Drosophila melanogaster, the neuropeptide leucokinin is required for the modulation of starvation-dependent changes in sleep. Leucokinin is expressed in numerous populations of neurons within the two compartments of the central nervous system: the brain and the ventral nerve cord. Both genetic manipulation and laser-mediated microablation experiments identify a single pair of neurons expressing this neuropeptide in the brain as being required for metabolic regulation of sleep. These neurons become active during periods of starvation and modulate the function of insulin-producing cells that are critical modulators of both sleep and feeding. Supporting this notion, knockdown of the leucokinin receptor within the insulin-producing cells also disrupts metabolic regulation of sleep. Taken together, these findings identify a critical role for leucokinin signaling in the integration of sleep and feeding states.
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Chatterjee A, Lamaze A, De J, Mena W, Chélot E, Martin B, Hardin P, Kadener S, Emery P, Rouyer F. Reconfiguration of a Multi-oscillator Network by Light in the Drosophila Circadian Clock. Curr Biol 2018; 28:2007-2017.e4. [PMID: 29910074 PMCID: PMC6039274 DOI: 10.1016/j.cub.2018.04.064] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2017] [Revised: 02/28/2018] [Accepted: 04/18/2018] [Indexed: 01/02/2023]
Abstract
The brain clock that drives circadian rhythms of locomotor activity relies on a multi-oscillator neuronal network. In addition to synchronizing the clock with day-night cycles, light also reformats the clock-driven daily activity pattern. How changes in lighting conditions modify the contribution of the different oscillators to remodel the daily activity pattern remains largely unknown. Our data in Drosophila indicate that light readjusts the interactions between oscillators through two different modes. We show that a morning s-LNv > DN1p circuit works in series, whereas two parallel evening circuits are contributed by LNds and other DN1ps. Based on the photic context, the master pacemaker in the s-LNv neurons swaps its enslaved partner-oscillator-LNd in the presence of light or DN1p in the absence of light-to always link up with the most influential phase-determining oscillator. When exposure to light further increases, the light-activated LNd pacemaker becomes independent by decoupling from the s-LNvs. The calibration of coupling by light is layered on a clock-independent network interaction wherein light upregulates the expression of the PDF neuropeptide in the s-LNvs, which inhibits the behavioral output of the DN1p evening oscillator. Thus, light modifies inter-oscillator coupling and clock-independent output-gating to achieve flexibility in the network. It is likely that the light-induced changes in the Drosophila brain circadian network could reveal general principles of adapting to varying environmental cues in any neuronal multi-oscillator system.
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Affiliation(s)
- Abhishek Chatterjee
- Institut des Neurosciences Paris-Saclay, Univ. Paris Sud, CNRS, Université Paris-Saclay, 91190 Gif-sur-Yvette, France
| | - Angélique Lamaze
- Institut des Neurosciences Paris-Saclay, Univ. Paris Sud, CNRS, Université Paris-Saclay, 91190 Gif-sur-Yvette, France
| | - Joydeep De
- Institut des Neurosciences Paris-Saclay, Univ. Paris Sud, CNRS, Université Paris-Saclay, 91190 Gif-sur-Yvette, France
| | - Wilson Mena
- Institut des Neurosciences Paris-Saclay, Univ. Paris Sud, CNRS, Université Paris-Saclay, 91190 Gif-sur-Yvette, France
| | - Elisabeth Chélot
- Institut des Neurosciences Paris-Saclay, Univ. Paris Sud, CNRS, Université Paris-Saclay, 91190 Gif-sur-Yvette, France
| | - Béatrice Martin
- Institut des Neurosciences Paris-Saclay, Univ. Paris Sud, CNRS, Université Paris-Saclay, 91190 Gif-sur-Yvette, France
| | - Paul Hardin
- Department of Biology and Center for Biological Clocks Research, Texas A&M University, College Station, TX 77845-3258, USA
| | | | - Patrick Emery
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - François Rouyer
- Institut des Neurosciences Paris-Saclay, Univ. Paris Sud, CNRS, Université Paris-Saclay, 91190 Gif-sur-Yvette, France.
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Bakayan A, Domingo B, Vaquero CF, Peyriéras N, Llopis J. Fluorescent Protein-photoprotein Fusions and Their Applications in Calcium Imaging. Photochem Photobiol 2017; 93:448-465. [PMID: 27925224 DOI: 10.1111/php.12682] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Accepted: 09/19/2016] [Indexed: 12/21/2022]
Abstract
Calcium-activated photoproteins, such as aequorin, have been used as luminescent Ca2+ indicators since 1967. After the cloning of aequorin in 1985, microinjection was substituted by its heterologous expression, which opened the way for a widespread use. Molecular fusion of green fluorescent protein (GFP) to aequorin recapitulated the nonradiative energy transfer process that occurs in the jellyfish Aequorea victoria, from which these two proteins were obtained, resulting in an increase of light emission and a shift to longer wavelength. The abundance and location of the chimera are seen by fluorescence, whereas its luminescence reports Ca2+ levels. GFP-aequorin is broadly used in an increasing number of studies, from organelles and cells to intact organisms. By fusing other fluorescent proteins to aequorin, the available luminescence color palette has been expanded for multiplexing assays and for in vivo measurements. In this report, we will attempt to review the various photoproteins available, their reported fusions with fluorescent proteins and their biological applications to image Ca2+ dynamics in organelles, cells, tissue explants and in live organisms.
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Affiliation(s)
- Adil Bakayan
- BioEmergences Unit (CNRS, USR3695), Université Paris-Saclay, Gif-sur-Yvette, France
| | - Beatriz Domingo
- Centro Regional de Investigaciones Biomédicas (CRIB) and Facultad de Medicina de Albacete, Universidad de Castilla-La Mancha, Albacete, Spain
| | - Cecilia F Vaquero
- Centro Regional de Investigaciones Biomédicas (CRIB) and Facultad de Medicina de Albacete, Universidad de Castilla-La Mancha, Albacete, Spain
| | - Nadine Peyriéras
- BioEmergences Unit (CNRS, USR3695), Université Paris-Saclay, Gif-sur-Yvette, France
| | - Juan Llopis
- Centro Regional de Investigaciones Biomédicas (CRIB) and Facultad de Medicina de Albacete, Universidad de Castilla-La Mancha, Albacete, Spain
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Lark AR, Kitamoto T, Martin JR. In Vivo Functional Brain Imaging Approach Based on Bioluminescent Calcium Indicator GFP-aequorin. J Vis Exp 2016. [PMID: 26779599 DOI: 10.3791/53705] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Functional in vivo imaging has become a powerful approach to study the function and physiology of brain cells and structures of interest. Recently a new method of Ca(2+)-imaging using the bioluminescent reporter GFP-aequorin (GA) has been developed. This new technique relies on the fusion of the GFP and aequorin genes, producing a molecule capable of binding calcium and - with the addition of its cofactor coelenterazine - emitting bright light that can be monitored through a photon collector. Transgenic lines carrying the GFP-aequorin gene have been generated for both mice and Drosophila. In Drosophila, the GFP-aequorin gene has been placed under the control of the GAL4/UAS binary expression system allowing for targeted expression and imaging within the brain. This method has subsequently been shown to be capable of detecting both inward Ca(2+)-transients and Ca(2+)-released from inner stores. Most importantly it allows for a greater duration in continuous recording, imaging at greater depths within the brain, and recording at high temporal resolutions (up to 8.3 msec). Here we present the basic method for using bioluminescent imaging to record and analyze Ca(2+)-activity within the mushroom bodies, a structure central to learning and memory in the fly brain.
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Affiliation(s)
- Arianna R Lark
- Equipe: Imagerie Cérébrale Fonctionnelle et Comportements (ICFC), Institut des Neurosciences Paris-Saclay (Nero-PSI), UMR-9197, CNRS/Université Paris Sud; Interdisciplinary Program in Neuroscience, Graduate College, University of Iowa
| | - Toshihiro Kitamoto
- Interdisciplinary Program in Neuroscience, Graduate College, University of Iowa; Department of Anesthesia, Carver College of Medicine, University of Iowa
| | - Jean-René Martin
- Equipe: Imagerie Cérébrale Fonctionnelle et Comportements (ICFC), Institut des Neurosciences Paris-Saclay (Nero-PSI), UMR-9197, CNRS/Université Paris Sud;
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PKA and cAMP/CNG Channels Independently Regulate the Cholinergic Ca(2+)-Response of Drosophila Mushroom Body Neurons. eNeuro 2015; 2:eN-NWR-0054-14. [PMID: 26464971 PMCID: PMC4596083 DOI: 10.1523/eneuro.0054-14.2015] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2014] [Revised: 04/03/2015] [Accepted: 04/08/2015] [Indexed: 01/22/2023] Open
Abstract
The mushroom bodies (MBs) are the most prominent structures in adult Drosophila brain. They have been involved in several crucial functions, such as learning and memory, sleep, locomotor activity, and decision making. The mushroom bodies (MBs), one of the main structures in the adult insect brain, play a critical role in olfactory learning and memory. Though historical genes such as dunce and rutabaga, which regulate the level of cAMP, were identified more than 30 years ago, their in vivo effects on cellular and physiological mechanisms and particularly on the Ca2+-responses still remain largely unknown. In this work, performed in Drosophila, we took advantage of in vivo bioluminescence imaging, which allowed real-time monitoring of the entire MBs (both the calyx/cell-bodies and the lobes) simultaneously. We imaged neuronal Ca2+-activity continuously, over a long time period, and characterized the nicotine-evoked Ca2+-response. Using both genetics and pharmacological approaches to interfere with different components of the cAMP signaling pathway, we first show that the Ca2+-response is proportional to the levels of cAMP. Second, we reveal that an acute change in cAMP levels is sufficient to trigger a Ca2+-response. Third, genetic manipulation of protein kinase A (PKA), a direct effector of cAMP, suggests that cAMP also has PKA-independent effects through the cyclic nucleotide-gated Ca2+-channel (CNG). Finally, the disruption of calmodulin, one of the main regulators of the rutabaga adenylate cyclase (AC), yields different effects in the calyx/cell-bodies and in the lobes, suggesting a differential and regionalized regulation of AC. Our results provide insights into the complex Ca2+-response in the MBs, leading to the conclusion that cAMP modulates the Ca2+-responses through both PKA-dependent and -independent mechanisms, the latter through CNG-channels.
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Majdi S, Ren L, Fathali H, Li X, Ewing AG. Selected recent in vivo studies on chemical measurements in invertebrates. Analyst 2015; 140:3676-86. [DOI: 10.1039/c4an02172j] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Review ofin vivoanalysis of brain chemicals in invertebrates.
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Affiliation(s)
- S. Majdi
- Department of Chemistry and Chemical Engineering
- Chalmers University of Technology
- Gothenburg
- Sweden
| | - L. Ren
- Department of Chemistry and Chemical Engineering
- Chalmers University of Technology
- Gothenburg
- Sweden
| | - H. Fathali
- Department of Chemistry and Chemical Engineering
- Chalmers University of Technology
- Gothenburg
- Sweden
| | - X. Li
- Department of Chemistry and Chemical Engineering
- Chalmers University of Technology
- Gothenburg
- Sweden
| | - A. G. Ewing
- Department of Chemistry and Chemical Engineering
- Chalmers University of Technology
- Gothenburg
- Sweden
- Department of Chemistry and Molecular Biology
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