Strand breaks induced in plasmid DNA by ultra soft X-rays : Influence of hydration and packing

A. Eschenbrenner (1) , M.-A. Herve Du Penhoat (1) , A. Boissiere (1) , G. Eot-Houllier (2) , F. Abel (3) , M.-F. Politis (1) , A. Touati (1) , E. Sage , A. Chetioui (1)

1 IMPMC - Institut de minéralogie et de physique des milieux condensés
2 Institut Curie [Paris]
3 INSP - Institut des Nanosciences de Paris

D oTostudytheeffectofhydrationlevel andplasmidpackingonstrandbreakinductioninDNAbyultrasoftX-ray. Materialsandmethods: Bluescript(pBS, tightpacking)andpSP189(pSP, loosepacking)plasmidswereirradiatedby250, 380, and760eVultrasoft X-rays at theLaboratoirepour l'UtilisationduRayonnement Electromagne ́tiquesynchrotron facility(Orsay, France). Singleanddoublestrandbreaks(SSBandDSB)werequantifiedbygel electrophoresis. Results: The number of DSB per Gray and per Dalton in pBS plasmids were (5.6+0.1), (6.3+0.1) and (8.5+0.4)610712at 250, 380and760eV, respectively. Theywererespectively1.4+0.1, 1.1+0.1and1.9+0.2times largerforpSPplasmids. SSB/DSBratiosvariedbetween4.4and6.4. Conclusion: Theobserveddependencyof strandbreakinductionbyultrasoft X-rays onthehydrationlevel of DNAin plasmidsfilmsmaybeassociatedwith: (i)Damagetransferfromthewatershell totheDNAand/or(ii)changeinpacking. 760eVphotonswhicharemoreoftenabsorbedinthehydrationshell andyieldlongerrangeelectronsthan250and380eV photons, inducemoreDSBperGrayandperDalton, especiallyforthelooserplasmid(pSP)

Mots clés: Ultrasoft X-rays; doublestrandbreaks; coreevents; plasmid; hydration

Domaines: Autre [cond-mat.other]

A. Eschenbrenner, M.-A. Herve Du Penhoat, A. Boissiere, G. Eot-Houllier, F. Abel, et al.. Strand breaks induced in plasmid DNA by ultra soft X-rays : Influence of hydration and packing. International Journal of Radiation Biology, 2007, 83, pp.687-697. ⟨10.1080/09553000701584106⟩. ⟨hal-00173156⟩