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w słowach kluczowych: pęknięcia DNA dwuniciowe

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Metoda znajdowania komórek i zliczania ognisk występowania histonu γ-H2AX w obrazach na potrzeby detekcji dwuniciowych pęknięć DNA

Wojciechowski P., Bal A.

Pomiary Automatyka Kontrola

2012

R. 58, nr 4

387-390

Niniejsza praca opisuje algorytm automatyzujący proces zliczania ognisk histonu γ-H2AX w obrazach mikroskopowych. Ogniska te są miejscami, w których doszło do fosforylacji białka histonu H2AX w pozycji seryny 139 wskutek dwuniciowych pęknięć DNA. Propono-wana metoda działa dwuetapowo. Najpierw w obrazie mikroskopowym selekcjonowane są obiekty uznawane za komórki, a następnie na obszarze tych obiektów poszukiwane są miejsca wyznakowane barwnikiem fluorescencyjnym związanym z przeciwciałem anty-γ-H2AX - miejsca te wskazują na lokalizację ognisk γ-H2AX.

This paper describes an algorithm for automating the process of counting foci of histone γ-H2AX in microscope images. Foci are the places where there occurred H2AX protein phosphorylation on Ser139 site in response to DNA double-strand breaks (DSBs). In a γ-H2AX genotoxic test the number of foci per a single cell is counted. The proposed method works in two stages. The first stage is segmentation of a microscopic image (Fig. 1a) for selecting cell regions. For this purpose fusion of binarization methods is used - for the each pixel the result is obtained by comparison of the results from the Otsu method, the triangle method and the method in which the threshold is equal to the image average brightness. The pixel is classified as an object's pixel when at least two methods give such results. For improving segmentation results a morphological filter is used. The results (Fig. 1b) usually comprise regions representing single cells (Fig. 1c) and a set of agglomerated cells (Fig. 1d). A modified watershed segmentation and region classify method is used for separation of agglomerated cells into regions representing only one cell. The final result (Fig.1e) contains only regions representing single cells. In the second stage for each single cell region the foci (which are marked with a fluorescent indicator joined with anti- γ-H2AX antibody) are found (Fig. 3) with use of watershed segmentation on the pseudogradient image (which is obtained by aggregation of the results of cell image binarization with different thresholds; Fig. 2). The final results in form of foci number as a function of time after irradiation (Fig. 4) are similar to the test results of non-lethal DNA damages founded in the literature (e.g. [5]) - this allows stating that the presented method gives good results.

Integration of DNA and bionical engineering

Goncharenko V. V., Loboda P. I., Goncharenko M. V., Heilmaier M.

International Journal of Applied Mechanics and Engineering

2011

Vol. 16, no 2

359-369

A unified geometric version of a mechanical model of a single stretched and compressed double-stranded DNA is suggested. This version is comfortable for use by scaling for development of bionical engineering models of a wide class of highly innovative devices.