[Cytogenetic investigations of bone marrow cells from mice exposed onboard biosatellite "Bion-M1"]

The results of studying the mitotic activities and chromosomal aberrations in bone marrow cells from C57/BL6N mice with the help of the anaphase technique in 12 hours after completion of the 30-day "Bion-M1" mission and ground-based experiment using flight equipment are presented. A statistically reliable decline of the mitotic activity (0.74%) was found in cells taken from the space flown animals. In the ground-based experiment, a statistically reliable downward trend in proliferative activity (1.37%) was revealed after the comparison with groups of vivarium control (1.46-1.53%). In both experiments mice increased the number of initial mitotic phases (prophase + metaphase) relative to the sum of anaphases and telophases. The number of aberrant mitoses grew reliably in the group of flight animals by 29.7%, whereas in the ground-based experiment an upward trend was insignificant as their number increased up to 2.3% only. In the vivarium controls aberrant mitoses constituted 1.75-1.8%. An increase in chromosomal aberrations was largely due to such abnormalities as fragments. These findings seem to have been a result of summation of the effects of radiation and other stressful factors in space flight.