Effect of UVC Light on Growth, Incorporation of Thymidine, and DNA Chain Elongation in Cells Derived from the Indian Meal Moth and the Cabbage Looper

Abstract

After exposure to 10 or 20 J/m2 UVC light, cells of the UMN-PIE-1181 line, an embryonic cell line derived from the Indian meal moth, Plodia interpunctella, exhibited a rapid and prolonged depression in the rate of incorporation of [3H]thymidine, whereas cells of the TN-368 line, an ovarian cell line derived from Trichoplusia ni, the cabbage looper, showed only a slight drop in incorporation and a rapid recovery after exposure to 10 or 40 J/m2 UVC light. The extent of this depression was not correlated to the amount of cell killing by UVC light in these cell lines or in IAL-PID2 cells. Blockage of fork progression was correlated to the depression in thymidine incorporation. TN-368 cells exhibited little blockage after exposure to 10 or 20 J/m2 UVC light, whereas UMN-PIE-1181 cells exhibited significant blockage at these fluences. Photoreactivation did not entirely relieve blockage, depression in thymidine incorporation, or cell killing, indicating that, although the (5-6) dimer appears to be the major lesion responsible for these effects, other lesions such as the (6-4) photoproduct may play a role.

Moths: Myths and mysteries of stress resistance

“…Although Drosophila cells were more sensitive to UV than the cabbage looper line, they were capable of photoreactivating nearly 80% of the UV damage, perhaps implying a larger role for cyclobutane-type pyrimidine dimers or 6-4 photoproducts in the lethality of these cells (29). Photoreactivation has been found to reverse the majority of UV-induced blockage of DNA fork progression in lepidopteran cells (30). While the looper cells are quite adept at photoreactivating DNA damage induced by 254 nm light, it should be remembered that the UV resistance demonstrated, even in the absence of photoreactivating light, was at least 12 times greater than for hamster cells.…”