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REMOVAL OF PYRIMIDINE DIMERS IN UV‐IRRADIATED SPORES OF Dictyostelium discoideum DURING GERMINATION
Author(s) -
Okaichi Kumio,
Tano Keizo,
Ohnishi Takeo,
Nozu Keiichi
Publication year - 1985
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1985.tb03618.x
Subject(s) - spore , germination , pyrimidine dimer , irradiation , microbiology and biotechnology , strain (injury) , biology , chemistry , botany , dna , biochemistry , dna damage , anatomy , physics , nuclear physics
— The spores of Dictyostelium discoideum TW‐8 ( radC ) are about twice as sensitive to UV than the parental strain NC‐4 spores at a 10% survival level. Ultraviolet irradiation apparently suppressed the emergence of amoebae from swollen TW‐8 spores as compared with NC‐4 spores, though the conversion of spores into swollen spores was not affected by UV irradiation in either strain. About 85% removal of pyrimidine dimers was detected in UV‐irradiated NC‐4 spores at 200 J/m 2 during spore germination for 9 h, but no removal of pyrimidine dimers was detected in TW‐8 spores under the same conditions. The removal of pyrimidine dimers from the NC‐4 spores began at around 2 h germination when the spores have become swollen. The number of enzyme‐sensitive sites (ESS) detected by Micrococcus luteus endonuclease in the DNA of UV‐irradiated NC‐4 spores also began to decrease at about 2 h into germination. The decrease in ESS, however, was hardly detectable in UV‐irradiated TW‐8 spores at any step during germination. Cycloheximide inhibited both decrease in the number of pyrimidine dimers, and decrease in the number of ESS of UV‐irradiated NC‐4 spores. It is suggested that UV‐specific endonuclease is newly synthesized in swollen spores of NC‐4.