Eur. Phys. J. Plus (2016) 131: 213
https://doi.org/10.1140/epjp/i2016-16213-5

Regular Article

MDI: integrity index of cytoskeletal fibers observed by AFM

¹ Dipartimento di Neuroscienze, Università degli Studi di Parma, via Volturno 39, 43125, Parma, Italy
² Museo Storico della Fisica e Centro Studi e Ricerche “Enrico Fermi”, Piazza del Viminale 1, 00184, Roma, Italy
³ INBB (Istituto Nazionale Biostrutture e Biosistemi), via delle medaglie d’Oro 305, Roma, Italy

^* e-mail: massimo.manghi@unipr.it

Received: 19 January 2016
Revised: 28 April 2016
Accepted: 22 May 2016
Published online: 24 June 2016

Abstract

The Modified Directional Index (MDI) is a form factor of the angular spectrum computed from the 2D Fourier transform of an image marking the prevalence of rectilinear features throughout the picture. We study some properties of the index and we apply it to AFM images of cell cytoskeleton regions featuring patterns of rectilinear nearly parallel actin filaments as in the case of microfilaments grouped in bundles. The analysis of AFM images through MDI calculation quantifies the fiber directionality changes which could be related to fiber damages. This parameter is applied to the images of Hs 578Bst cell line, non-tumoral and not immortalized human epithelial cell line, irradiated with X-rays at doses equivalent to typical radiotherapy treatment fractions. In the reported samples, we could conclude that the damages are mainly born to the membrane and not to the cytoskeleton. It could be interesting to test the parameter also using other kinds of chemical or physical agents.