International Mammalian Genome Society

17th International Mouse Genome Conference

9-12 November 2003, Braunschweig, Germany


POSTER 49 - BIODOSIMETRY BY DETECTING Γ-H2AX FOCI IN CB.17 MOUSE PERIPHERAL LYMPHOCYTES, ORGAN TISSUES AND SCID LYMPHOMA CELLS AFTER 137CS Γ-RAY IRRADIATION

Nakajima H
Osaka University

Co-Authors: Tsuboi R, Nomura T
Institutions: Osaka University

To measure the radiation damage, γ-H2AX foci in the irradiated CB.17 peripheral lymphocytes, organ tissues and SCID lymphoma cell line established from CB.17 scid/scid mice were detected as fluorescent signals, since phosphorylation of H2AX by PI3 kinase at serine 139 (γ-H2AX) occurs following DNA double strand- but not single-strand break induction and is probably the earliest manifestation of the lesion.

CB. 17 mice and SCID lymphoma cells were exposed to 0, 0.1, 0.2, 0.5, 1, 2, 4 Gy (1 Gy / min) of γ-rays. The γ-H2AX foci were detected as fluorescent signals in both cells at 3 minutes after irradiation and the signal intensity reached maximum within 30 minutes after exposure, and then faded quickly. Dose dependent signal amplification was also observed.

These results suggest that quantitation of DNA double strand- breaks ( DSBs ) by the γ-H2AX foci is an useful biodosimeter for detecting high and low dose radiation damage in mice. It is also suggested that there is a threshold dose which can not be discriminated the additional radiation induced DSBs from spontaneous DSBs in a cell.

Additionally, genes related to the H2AX phosphorylation are supposed to express in all cells of organs to repair spontaneous DSBs caused environmental effects, e.g. radiations and chemicals, however, it seems that theses essential systems are not working in all organs (Ex. small intestine).


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