title: Analysis of the spatial organization of molecules with robust statistics.
abstract: One major question in molecular biology is whether the spatial distribution of observed molecules is random or organized in clusters. Indeed, this analysis gives information about molecules' interactions and physical interplay with their environment. The standard tool for analyzing molecules' distribution statistically is the Ripley's K function, which tests spatial randomness through the computation of its critical quantiles. However, quantiles' computation is very cumbersome, hindering its use. Here, we present an analytical expression of these quantiles, leading to a fast and robust statistical test, and we derive the characteristic clusters' size from the maxima of the Ripley's K function. Subsequently, we analyze the spatial organization of endocytic spots at the cell membrane and we report that clathrin spots are randomly distributed while clathrin-independent spots are organized in clusters with a radius of 2 μm, which suggests distinct physical mechanisms and cellular functions for each pathway.
authors.affiliation: Unité d'Analyse d'Images Quantitative, Institut Pasteur, Paris, France ; Unité de Recherche Associée 2582, Centre National de la Recherche Scientifique, Paris, France.
authors.forename: Thibault
authors.initials: T
authors.lastname: Lagache
authors.affiliation: Unité Mixte de Recherche 518 Mathématiques et Informatique Appliquées, AgroParisTech and INRA, Paris, France.
authors.forename: Gabriel
authors.initials: G
authors.lastname: Lang
authors.affiliation: Unité de Biologie des Interactions Cellulaires, Institut Pasteur, Paris, France ; Unité de Recherche Associée 2582, Centre National de la Recherche Scientifique, Paris, France.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Sauvonnet
authors.affiliation: Unité d'Analyse d'Images Quantitative, Institut Pasteur, Paris, France ; Unité de Recherche Associée 2582, Centre National de la Recherche Scientifique, Paris, France.
authors.forename: Jean-Christophe
authors.initials: JC
authors.lastname: Olivo-Marin
mesh_terms: D002966:Clathrin / Q000737:chemistry; D008954:Models, Biological; D008962:Models, Theoretical
chemical_list: D002966:Clathrin