title: A new tool for the quantitative analysis of dendritic filopodial motility.
abstract: Dendritic filopodia are tiny and highly motile protrusions formed along the dendrites of neurons. During the search for future presynaptic partners, their shape and size change dynamically, with a direct impact on the formation, stabilization and maintenance of synaptic connections both in vivo and in vitro. In order to reveal molecular players regulating synapse formation, quantitative analysis of dendritic filopodia motility is needed. Defining the length or the tips of these protrusions manually, however, is time consuming, limiting the extent of studies as well as their statistical power. Additionally, area detection based on defining a single intensity threshold can lead to significant errors throughout the image series, as these small structures often have low contrast in fluorescent images. To overcome these problems, the open access Dendritic Filopodia Motility Analyzer, a semi-automated ImageJ/Fiji plugin was created. Our method calculates the displacement of the centre of mass (CoM) within a selected region based on the weighted intensity values of structure forming pixels, selected by upper and lower intensity thresholds. Using synthetic and real biological samples, we prove that the displacement of the weighted CoM reliably characterizes the motility of dendritic protrusions. Additionally, guidelines to define optimal parameters of live cell recordings from dendritic protrusions are provided. © 2014 International Society for Advancement of Cytometry.
authors.affiliation: Department of Physiology and Neurobiology, Eötvös Loránd University, Pázmány P. stny. 1/C, H-1117, Budapest, Hungary.
authors.forename: Krisztián
authors.initials: K
authors.lastname: Tárnok
authors.forename: Márton
authors.initials: M
authors.lastname: Gulyás
authors.forename: Norbert
authors.initials: N
authors.lastname: Bencsik
authors.forename: Katalin
authors.initials: K
authors.lastname: Ferenc
authors.forename: Klaus
authors.initials: K
authors.lastname: Pfizenmaier
authors.forename: Angelika
authors.initials: A
authors.lastname: Hausser
authors.forename: Katalin
authors.initials: K
authors.lastname: Schlett
mesh_terms: D000818:Animals; D002465:Cell Movement; D003592:Cytophotometry / Q000295:instrumentation* / Q000379:methods; D003712:Dendrites / Q000378:metabolism / Q000648:ultrastructure*; D004622:Embryo, Mammalian; D015870:Gene Expression; D017930:Genes, Reporter; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D006624:Hippocampus / Q000378:metabolism / Q000648:ultrastructure; D007091:Image Processing, Computer-Assisted; D051379:Mice; D061251:Primary Cell Culture; D011554:Pseudopodia / Q000378:metabolism / Q000648:ultrastructure*; D013569:Synapses / Q000378:metabolism / Q000648:ultrastructure*; D059008:Time-Lapse Imaging / Q000295:instrumentation* / Q000379:methods
chemical_list: C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins
keywords: dendritic filopodia; motility analysis; neuron; time-lapse