Experiments were conducted with the A87 Xenopus tissue culture cell line which centered on use of the line's efficient photoreactivation (PR) mechanism to: (1) determine the extent to which sister chromatid exchanges (SCEs), induced by exposing early G1 phase cells to low UV fluenced, are photoreactivable, and (2) determine the extent to which the photoreactivable SCEs resulting from these low UV fluences constitute lethal lesions. For the first determination, UV fluences - SCE frequency relations and UV fluence + PR fluence - SCE frequency relations were established for UV fluences in the range 0-12 J/m2 and a single PR fluence of 22,000 J/m2. Comparison of these relations indicated that the cells photoreactivated a predominant fraction (near .70) of the induced SCEs. For the second determination, a detailed time course of PR of induced SCEs relation and a time course of PR of induced lethality relation were established for the cells, using a single UV fluence of 5.0 J/m2 and a single PR fluence of 22,000 J/M2.Comparison of these relations indicated that few, if any, photoreactivable SCEs constituted photoreactivable lethal lesions. This comparison also suggested that further high resolution cytological studies of time course of PR of UV-induced SCEs may reveal additional relations between repair of SCEs and changes in vertebrate chromosome structure as cells progress through interphase.
Laswell, Dawn; Barber, Jennifer; and Griggs, H. Gaston
"Photoreactivation of UV-Induced Damage in G1 Phase Xenopus Cells That Leads to a Sister Chromatid Exchanged and Cell Death,"
Journal of the Arkansas Academy of Science: Vol. 45
, Article 16.
Available at: http://scholarworks.uark.edu/jaas/vol45/iss1/16