title: Sublethal gamma irradiation affects reproductive impairment and elevates antioxidant enzyme and DNA repair activities in the monogonont rotifer Brachionus koreanus.
abstract: To examine the effects of gamma radiation on marine organisms, we irradiated several doses of gamma ray to the microzooplankton Brachionus koreanus, and measured in vivo and in vitro endpoints including the survival rate, lifespan, fecundity, population growth, gamma ray-induced oxidative stress, and modulated patterns of enzyme activities and gene expressions after DNA damage. After gamma radiation, no individuals showed any mortality within 96 h even at a high intensity (1200 Gy). However, a reduced fecundity (e.g. cumulated number of offspring) of B. koreanus at over 150 Gy was observed along with a slight decrease in lifespan. At 150 Gy and 200 Gy, the reduced fecundity of the rotifers led to a significant decrease in population growth, although in the second generation the population growth pattern was not affected even at 200 Gy when compared to the control group. At sub-lethal doses, reactive oxygen species (ROS) levels dose-dependently increased with GST enzyme activity. In addition, up-regulations of the antioxidant and chaperoning genes in response to gamma radiation were able to recover cellular damages, and life table parameters were significantly influenced, particularly with regard to fecundity. DNA repair-associated genes showed significantly up-regulated expression patterns in response to sublethal doses (150 and 200 Gy), as shown in the expression of the gamma-irradiated B. koreanus p53 gene, suggesting that these sublethal doses were not significantly fatal to B. koreanus but induced DNA damages leading to a decrease of the population size.
authors.affiliation: Department of Biological Sciences, College of Science, Sungkyunkwan University, Suwon 440-746, South Korea.
authors.forename: Jeonghoon
authors.initials: J
authors.lastname: Han
authors.affiliation: Department of Biological Sciences, College of Science, Sungkyunkwan University, Suwon 440-746, South Korea.
authors.forename: Eun-Ji
authors.initials: EJ
authors.lastname: Won
authors.affiliation: Division of Life Sciences, Korea Polar Research Institute, Incheon 406-840, South Korea.
authors.forename: Il-Chan
authors.initials: IC
authors.lastname: Kim
authors.affiliation: Division of Life Sciences, Korea Polar Research Institute, Incheon 406-840, South Korea.
authors.forename: Joung Han
authors.initials: JH
authors.lastname: Yim
authors.affiliation: Department of Life Science, College of Natural Sciences, Hanyang University, Seoul 133-791, South Korea.
authors.forename: Su-Jae
authors.initials: SJ
authors.lastname: Lee
authors.affiliation: Department of Biological Sciences, College of Science, Sungkyunkwan University, Suwon 440-746, South Korea. Electronic address: jslee2@skku.edu.
authors.forename: Jae-Seong
authors.initials: JS
authors.lastname: Lee
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000378:metabolism; D004249:DNA Damage; D004260:DNA Repair / Q000528:radiation effects*; D005720:Gamma Rays; D005786:Gene Expression Regulation / Q000528:radiation effects; D005978:Glutathione / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D012098:Reproduction / Q000502:physiology / Q000528:radiation effects; D012403:Rotifera / Q000201:enzymology / Q000378:metabolism / Q000528:radiation effects*; D014874:Water Pollutants, Chemical / Q000378:metabolism
chemical_list: D000975:Antioxidants; D017382:Reactive Oxygen Species; D014874:Water Pollutants, Chemical; D005978:Glutathione
keywords: DNA damage; DNA repair; Gamma radiation; Offspring; Reactive oxygen species; Rotifer