title: Tolerance of spermatogonia to oxidative stress is due to high levels of Zn and Cu/Zn superoxide dismutase.
abstract: BACKGROUND
  Spermatogonia are highly tolerant to reactive oxygen species (ROS) attack while advanced-stage germ cells such as spermatozoa are much more susceptible, but the precise reason for this variation in ROS tolerance remains unknown.
  
  
  RESULTS
  Using the Japanese eel testicular culture system that enables a complete spermatogenesis in vitro, we report that advanced-stage germ cells undergo intense apoptosis and exhibit strong signal for 8-hydroxy-2'-deoxyguanosine, an oxidative DNA damage marker, upon exposure to hypoxanthine-generated ROS while spermatogonia remain unaltered. Activity assay of antioxidant enzyme, superoxide dismutase (SOD) and Western blot analysis using an anti-Copper/Zinc (Cu/Zn) SOD antibody showed a high SOD activity and Cu/Zn SOD protein concentration during early spermatogenesis. Immunohistochemistry showed a strong expression for Cu/Zn SOD in spermatogonia but weak expression in advanced-stage germ cells. Zn deficiency reduced activity of the recombinant eel Cu/Zn SOD protein. Cu/Zn SOD siRNA decreased Cu/Zn SOD expression in spermatogonia and led to increased oxidative damage.
  
  
  CONCLUSIONS
  These data indicate that the presence of high levels of Cu/Zn SOD and Zn render spermatogonia resistant to ROS, and consequently protected from oxidative stress. These findings provide the biochemical basis for the high tolerance of spermatogonia to oxidative stress.
authors.affiliation: Research Group for Reproductive Physiology, South Ehime Fisheries Research Center, Ehime University, Ainan, Ehime, Japan.
authors.forename: Fritzie T
authors.initials: FT
authors.lastname: Celino
authors.forename: Sonoko
authors.initials: S
authors.lastname: Yamaguchi
authors.forename: Chiemi
authors.initials: C
authors.lastname: Miura
authors.forename: Takashi
authors.initials: T
authors.lastname: Ohta
authors.forename: Yuzuru
authors.initials: Y
authors.lastname: Tozawa
authors.forename: Toshiharu
authors.initials: T
authors.lastname: Iwai
authors.forename: Takeshi
authors.initials: T
authors.lastname: Miura
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology; D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D006063:Chorionic Gonadotropin / Q000494:pharmacology; D004524:Eels; D019271:Hypoxanthine / Q000494:pharmacology; D008297:Male; D018384:Oxidative Stress / Q000187:drug effects / Q000502:physiology*; D034741:RNA, Small Interfering / Q000494:pharmacology; D017382:Reactive Oxygen Species / Q000378:metabolism; D013091:Spermatogenesis / Q000187:drug effects / Q000502:physiology; D013093:Spermatogonia / Q000201:enzymology / Q000378:metabolism*; D013482:Superoxide Dismutase / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D013737:Testis / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D015032:Zinc / Q000378:metabolism* / Q000502:physiology
chemical_list: D006063:Chorionic Gonadotropin; D034741:RNA, Small Interfering; D017382:Reactive Oxygen Species; D019271:Hypoxanthine; D013482:Superoxide Dismutase; D015032:Zinc