title: Radioadaptive response in primary mouse spermatocytes revealed by analysis of synaptonemal complexes.
abstract: This study was aimed at estimating the damage to the synaptonemal complex (SC) of male mice caused by radiation exposure at the ultimate pre-meiotic interphase. Four experimental groups were formed: group 1 was an untreated control, group 2 received a low dose (50 mGy) of radiation, group 3 a high dose (4 Gy) of radiation, group 4 was first treated with a low dose (50 mGy) and 4 h later with a high dose (4 Gy). Mice were killed 4 days after the treatment. Early pachytene cells were selected for the electron microscopic analysis of SCs. These cells were supposed to be at pre-meiotic interphase at the time of irradiation. Treatment with a low dose of radiation did not produce any substantial increase in the frequency of SC aberrations, while exposure to the high dose resulted in various types of damage. Group 4 demonstrated significantly lower frequencies of axial breaks/fragments and multiaxial configurations than group 3. At the same time, these two groups did not differ in the frequencies of inter- and intrachromosomal exchanges such as translocations, inversions, and deletions. We suppose that the number of breaks produced by a high dose of radiation was the same in the both groups. However, a proportion of the breaks that remained unrepaired until pachytene and were expressed as gaps, fragments, and multiaxial configurations was reduced by pretreatment with the low dose of radiation.
authors.affiliation: Institute of Cytology and Genetics, Novosibirsk, Russia.
authors.forename: P M
authors.initials: PM
authors.lastname: Borodin
authors.forename: M
authors.initials: M
authors.lastname: Inouye
authors.forename: S
authors.initials: S
authors.lastname: Oda
authors.forename: T
authors.initials: T
authors.lastname: Ikushima
authors.forename: Y
authors.initials: Y
authors.lastname: Takagishi
authors.forename: H
authors.initials: H
authors.lastname: Yamamura
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D004307:Dose-Response Relationship, Radiation; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D008854:Microscopy, Electron; D011836:Radiation Tolerance; D013090:Spermatocytes / Q000502:physiology / Q000528:radiation effects* / Q000648:ultrastructure; D013573:Synaptonemal Complex / Q000528:radiation effects*