MYOCARD OF mdx MICE CONTAINS FACTOR(S) THAT DAMAGE DNA STRUCTURE AND SEEM TO
RETARD DNA REPARATION AFTER γ-IRRADIATION (EXPERIENCES IN MODELLING SYSTEM)
V. M. Mikhailov,1 V. D. Zhestyanikov, G. E. Saveljeva
Institute of Cytology RAS, St. Petersburg;
1 e-mail: vmikhailov@mail.cytspb.rssi.ru
We studied the action of saline extracts of ventricle myocard (EM) of C57BL and mdx mice on DNA structure and
repair of one-strand breaks of DNA in a modelling system. The system involves DNA repair in Å. coli
WP2 cells after γ-irradiation. Using standard technique, DNA reparation was estimated on measuring the speed
of Å. coli DNA sedimentation in alkaline sucrose gradients. It was shown, that EM of C57BL or mdx mice
exerted no ifluence on DNA repair, which was completely declined within 60 min with EM present in the growth
medium of permeabilized Å. coli. Addition of C57BL mice EM into lytic solution does not accelerate DNA
sedimentation of nonirradiated Å. coli. At the same time, EM of mdx mice sharply accelerates DNA
sedimentation of nonirradiated Å. coli reducing DNA molecular weight from
200 · 106 äî 135 · 106 Da. At entering in the lytic solutin the EM of mdx mice
also slows down Å. coli DNA repair after γ-irradiation. It is supposed, that EM of mdx mice may
contain a factor(s) damaging DNA in the γ lysate and presumably slowing down DNA reparation after
γ-irradiation. Russian Foundation of Basic Research Grants 99-04-49390, 02-04-49870 and 00-04-49390.
Key words: mdx mice, myocardium saline extract, γ-irradiation, Å. coli, DNA one
strand breaks
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