title: Wavelet transform analysis of chromatin texture changes during heat shock.
abstract: Texture analysis can be a useful tool to investigate the organization of chromatin. Approaches based on multiscale analysis and in particular the 'à trou' wavelet analysis has already been used for microscopy (Olivo Marin). In order to analyse texture changes, the statistical properties of the wavelet coefficient images were summarized by the first four statistical orders: mean, standard deviation, skewness and kurtosis of the coefficient image histogram. The 'à trou' transform provided a representation of the wavelet coefficients and texture parameters with the same statistical robustness throughout the scale spaces. It was applied for quantifying chromatin texture and heat-induced chromatin changes in living cells. We investigated the changes by both laser scanning and spinning disk confocal microscopies and compared the texture parameters before and after increasing duration of heat shock exposure (15 min, 30 min and 1 h). Furthermore, as activation of the heat shock response also correlates with a rapid localization of HSF1 within a few nuclear structures termed nuclear stress bodies (nSBs), we compared the dynamics of nSBs formation with that of textural changes during 1 h of continuous heat shock. Next, we studied the recovery phase following a 1-h heat shock. Significant differences were observed, particularly affecting the perinucleolar region, even for the shortest heat shock time affecting mostly the skewness and standard deviation. Furthermore, progressive changes could be observed according to the duration of heat shock, mostly affecting fine details (pixel-wise changes) as revealed by the parameters, obtained from the first- and second-order wavelet coefficients. 'A trou' wavelet texture analysis provided a sensitive and efficient tool to investigate minute changes of chromatin.
authors.affiliation: INSERM, IAB, University Grenoble Alpes, Grenoble, France.
authors.forename: G
authors.initials: G
authors.lastname: Herbomel
authors.affiliation: INSERM, IAB, University Grenoble Alpes, Grenoble, France.
authors.forename: A
authors.initials: A
authors.lastname: Grichine
authors.affiliation: CNRS, TIMC-IMAG, University Grenoble Alpes, Grenoble, France.
authors.forename: A
authors.initials: A
authors.lastname: Fertin
authors.affiliation: CNRS, LIPHY, University Grenoble Alpes, Grenoble, France.
authors.forename: A
authors.initials: A
authors.lastname: Delon
authors.affiliation: INSERM, IAB, University Grenoble Alpes, Grenoble, France.
authors.forename: C
authors.initials: C
authors.lastname: Vourc'h
authors.affiliation: INSERM, IAB, University Grenoble Alpes, Grenoble, France.
authors.forename: C
authors.initials: C
authors.lastname: Souchier
authors.affiliation: CNRS, TIMC-IMAG, University Grenoble Alpes, Grenoble, France.
authors.forename: Y
authors.initials: Y
authors.lastname: Usson
mesh_terms: D000465:Algorithms; D002470:Cell Survival; D002843:Chromatin / Q000737:chemistry / Q000378:metabolism*; D006367:HeLa Cells; D000076249:Heat Shock Transcription Factors / Q000378:metabolism; D018869:Heat-Shock Response / Q000502:physiology*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D018613:Microscopy, Confocal / Q000379:methods; D058067:Wavelet Analysis
chemical_list: D002843:Chromatin; C000619706:HSF1 protein, human; D000076249:Heat Shock Transcription Factors
keywords: Chromatin; confocal fluorescence microscopy; heat shock; living cell; texture; wavelet