The comparative study of different species could be of interest, both
applied and pure, to the field of cytogenetic damage induced by genoto
xic agents. For as accurate as possible an evaluation of the inter-spe
cies response differences to radiation, we have carried out a comparis
on between the behaviors of human and canine lymphocytes, using the mi
cronucleus assay (MN test) according to the cytokinesis-block method.
Up to 4 Gy doses, canine lymphocytes have been found to be about three
times more radiosensitive than human lymphocytes, due to blastization
inhibition (binucleation failure), and, for 1 and 2 Gy doses, about 1
.3 times more radiosensitive, due to MN yields. We discuss whether the
differing chromosome number (dog 78 and man 46) could have any effect
on the cytogenetic response. 3-Aminobenzamide, which inhibits poly(AD
P-ribose)polymerase activity, is able to increase the genotoxic effect
of X-rays in human lymphocytes, with a different response at the indi
vidual level. The same phenomenon with the same characteristics is als
o found in canine lymphocytes at the inter-individual level. Our in vi
tro radiobiological study confirms that the cytogenetic response obtai
ned in blood from selected breeds of mammalian species can be utilized
for applications in environmental studies.