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Fan WJ, Yan MC, Wang L, Sun YZ, Deng JB, Deng JX. Synaptic aging disrupts synaptic morphology and function in cerebellar Purkinje cells. Neural Regen Res 2018; 13:1019-1025. [PMID: 29926829 PMCID: PMC6022458 DOI: 10.4103/1673-5374.233445] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Synapses are key structures in neural networks, and are involved in learning and memory in the central nervous system. Investigating synaptogenesis and synaptic aging is important in understanding neural development and neural degeneration in diseases such as Alzheimer disease and Parkinson's disease. Our previous study found that synaptogenesis and synaptic maturation were harmonized with brain development and maturation. However, synaptic damage and loss in the aging cerebellum are not well understood. This study was designed to investigate the occurrence of synaptic aging in the cerebellum by observing the ultrastructural changes of dendritic spines and synapses in cerebellar Purkinje cells of aging mice. Immunocytochemistry, DiI diolistic assays, and transmission electron microscopy were used to visualize the morphological characteristics of synaptic buttons, dendritic spines and synapses of Purkinje cells in mice at various ages. With synaptic aging in the cerebellum, dendritic spines and synaptic buttons were lost, and the synaptic ultrastructure was altered, including a reduction in the number of synaptic vesicles and mitochondria in presynaptic termini and smaller thin specialized zones in pre- and post-synaptic membranes. These findings confirm that synaptic morphology and function is disrupted in aging synapses, which may be an important pathological cause of neurodegenerative diseases.
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Affiliation(s)
- Wen-Juan Fan
- Institute of Neurobiology, School of Life Science, Henan University, Kaifeng, Henan Province, China
| | - Ming-Chao Yan
- Institute of Neurobiology, School of Life Science, Henan University, Kaifeng, Henan Province, China
| | - Lai Wang
- Institute of Neurobiology, School of Life Science, Henan University, Kaifeng, Henan Province, China
| | - Yi-Zheng Sun
- Institute of Neurobiology, School of Life Science, Henan University, Kaifeng, Henan Province, China
| | - Jin-Bo Deng
- Institute of Neurobiology, School of Life Science, Henan University, Kaifeng, Henan Province, China
| | - Jie-Xin Deng
- Institute of Neurobiology, School of Life Science, Henan University, Kaifeng, Henan Province, China
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Sugie A, Möhl C, Hakeda-Suzuki S, Matsui H, Suzuki T, Tavosanis G. Analyzing Synaptic Modulation of Drosophila melanogaster Photoreceptors after Exposure to Prolonged Light. J Vis Exp 2017. [PMID: 28287587 DOI: 10.3791/55176] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
The nervous system has the remarkable ability to adapt and respond to various stimuli. This neural adjustment is largely achieved through plasticity at the synaptic level. The Active Zone (AZ) is the region at the presynaptic membrane that mediates neurotransmitter release and is composed of a dense collection of scaffold proteins. AZs of Drosophila melanogaster (Drosophila) photoreceptors undergo molecular remodeling after prolonged exposure to natural ambient light. Thus the level of neuronal activity can rearrange the molecular composition of the AZ and contribute to the regulation of the functional output. Starting from the light exposure set-up preparation to the immunohistochemistry, this protocol details how to quantify the number, the spatial distribution, and the delocalization level of synaptic molecules at AZs in Drosophila photoreceptors. Using image analysis software, clusters of the GFP-fused AZ component Bruchpilot were identified for each R8 photoreceptor (R8) axon terminal. Detected Bruchpilot spots were automatically assigned to individual R8 axons. To calculate the distribution of spot frequency along the axon, we implemented a customized software plugin. Each axon's start-point and end-point were manually defined and the position of each Bruchpilot spot was projected onto the connecting line between start and end-point. Besides the number of Bruchpilot clusters, we also quantified the delocalization level of Bruchpilot-GFP within the clusters. These measurements reflect in detail the spatially resolved synaptic dynamics in a single neuron under different environmental conditions to stimuli.
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Affiliation(s)
- Atsushi Sugie
- Department of Neuroscience of Disease, Center for Transdisciplinary Research, Niigata University; Brain Research Institute, Niigata University; Dendrite Differentiation, German Center for Neurodegenerative Diseases (DZNE);
| | - Christoph Möhl
- Image and Data Analysis Facility, German Center for Neurodegenerative Diseases (DZNE);
| | - Satoko Hakeda-Suzuki
- Graduate School of Life Science and Technology, Tokyo Institute of Technology (Titech)
| | - Hideaki Matsui
- Department of Neuroscience of Disease, Center for Transdisciplinary Research, Niigata University; Brain Research Institute, Niigata University
| | - Takashi Suzuki
- Graduate School of Life Science and Technology, Tokyo Institute of Technology (Titech)
| | - Gaia Tavosanis
- Dendrite Differentiation, German Center for Neurodegenerative Diseases (DZNE)
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Huang BFF, Boutros PC. The parameter sensitivity of random forests. BMC Bioinformatics 2016; 17:331. [PMID: 27586051 PMCID: PMC5009551 DOI: 10.1186/s12859-016-1228-x] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Accepted: 08/26/2016] [Indexed: 02/07/2023] Open
Abstract
Background The Random Forest (RF) algorithm for supervised machine learning is an ensemble learning method widely used in science and many other fields. Its popularity has been increasing, but relatively few studies address the parameter selection process: a critical step in model fitting. Due to numerous assertions regarding the performance reliability of the default parameters, many RF models are fit using these values. However there has not yet been a thorough examination of the parameter-sensitivity of RFs in computational genomic studies. We address this gap here. Results We examined the effects of parameter selection on classification performance using the RF machine learning algorithm on two biological datasets with distinct p/n ratios: sequencing summary statistics (low p/n) and microarray-derived data (high p/n). Here, p, refers to the number of variables and, n, the number of samples. Our findings demonstrate that parameterization is highly correlated with prediction accuracy and variable importance measures (VIMs). Further, we demonstrate that different parameters are critical in tuning different datasets, and that parameter-optimization significantly enhances upon the default parameters. Conclusions Parameter performance demonstrated wide variability on both low and high p/n data. Therefore, there is significant benefit to be gained by model tuning RFs away from their default parameter settings. Electronic supplementary material The online version of this article (doi:10.1186/s12859-016-1228-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Barbara F F Huang
- Informatics and Bio-computing Program, Ontario Institute for Cancer Research, Toronto, Canada
| | - Paul C Boutros
- Informatics and Bio-computing Program, Ontario Institute for Cancer Research, Toronto, Canada. .,Department of Medical Biophysics, University of Toronto, Toronto, Canada. .,Department of Pharmacology and Toxicology, University of Toronto, Toronto, Canada. .,MaRS Centre, 661 University Avenue, Suite 510, Toronto, Ontario, M5G 0A3, Canada.
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Belmer A, Klenowski PM, Patkar OL, Bartlett SE. Mapping the connectivity of serotonin transporter immunoreactive axons to excitatory and inhibitory neurochemical synapses in the mouse limbic brain. Brain Struct Funct 2016; 222:1297-1314. [PMID: 27485750 PMCID: PMC5368196 DOI: 10.1007/s00429-016-1278-x] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Accepted: 07/20/2016] [Indexed: 12/25/2022]
Abstract
Serotonin neurons arise from the brainstem raphe nuclei and send their projections throughout the brain to release 5-HT which acts as a modulator of several neuronal populations. Previous electron microscopy studies in rats have morphologically determined the distribution of 5-HT release sites (boutons) in certain brain regions and have shown that 5-HT containing boutons form synaptic contacts that are either symmetric or asymmetric. In addition, 5-HT boutons can form synaptic triads with the pre- and postsynaptic specializations of either symmetrical or asymmetrical synapses. However, due to the labor intensive processing of serial sections required by electron microscopy, little is known about the neurochemical properties or the quantitative distribution of 5-HT triads within whole brain or discrete subregions. Therefore, we used a semi-automated approach that combines immunohistochemistry and high-resolution confocal microscopy to label serotonin transporter (SERT) immunoreactive axons and reconstruct in 3D their distribution within limbic brain regions. We also used antibodies against key pre- (synaptophysin) and postsynaptic components of excitatory (PSD95) or inhibitory (gephyrin) synapses to (1) identify putative 5-HTergic boutons within SERT immunoreactive axons and, (2) quantify their close apposition to neurochemical excitatory or inhibitory synapses. We provide a 5-HTergic axon density map and have determined the ratio of synaptic triads consisting of a 5-HT bouton in close proximity to either neurochemical excitatory or inhibitory synapses within different limbic brain areas. The ability to model and map changes in 5-HTergic axonal density and the formation of triadic connectivity within whole brain regions using this rapid and quantitative approach offers new possibilities for studying neuroplastic changes in the 5-HTergic pathway.
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Affiliation(s)
- Arnauld Belmer
- Translational Research Institute, Queensland University of Technology, Brisbane, Qld 4059, Australia
| | - Paul M Klenowski
- Translational Research Institute, Queensland University of Technology, Brisbane, Qld 4059, Australia
| | - Omkar L Patkar
- Translational Research Institute, Queensland University of Technology, Brisbane, Qld 4059, Australia
| | - Selena E Bartlett
- Translational Research Institute, Queensland University of Technology, Brisbane, Qld 4059, Australia. .,Institute of Health and Biomedical Innovation (IHBI), Queensland University of Technology, Brisbane, Australia.
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Peng H, Zhou J, Zhou Z, Bria A, Li Y, Kleissas DM, Drenkow NG, Long B, Liu X, Chen H. Bioimage Informatics for Big Data. ADVANCES IN ANATOMY, EMBRYOLOGY, AND CELL BIOLOGY 2016; 219:263-72. [PMID: 27207370 DOI: 10.1007/978-3-319-28549-8_10] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Bioimage informatics is a field wherein high-throughput image informatics methods are used to solve challenging scientific problems related to biology and medicine. When the image datasets become larger and more complicated, many conventional image analysis approaches are no longer applicable. Here, we discuss two critical challenges of large-scale bioimage informatics applications, namely, data accessibility and adaptive data analysis. We highlight case studies to show that these challenges can be tackled based on distributed image computing as well as machine learning of image examples in a multidimensional environment.
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Affiliation(s)
- Hanchuan Peng
- Allen Institute for Brain Science, Seattle, WA, USA.
| | - Jie Zhou
- Department of Computer Science, Northern Illinois University, Dekalb, IL, USA
| | - Zhi Zhou
- Allen Institute for Brain Science, Seattle, WA, USA
| | - Alessandro Bria
- Department of Engineering, University Campus Bio-Medico of Rome, Rome, Italy.,Department of Electrical and Information Engineering, University of Cassino and L.M., Cassino, Italy
| | - Yujie Li
- Allen Institute for Brain Science, Seattle, WA, USA.,Department of Computer Science, University of Georgia, Athens, GA, USA
| | | | - Nathan G Drenkow
- Johns Hopkins University Applied Physics Laboratory, Laurel, MD, USA
| | - Brian Long
- Allen Institute for Brain Science, Seattle, WA, USA
| | - Xiaoxiao Liu
- Allen Institute for Brain Science, Seattle, WA, USA
| | - Hanbo Chen
- Allen Institute for Brain Science, Seattle, WA, USA.,Department of Computer Science, University of Georgia, Athens, GA, USA
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