Influence of Thermal Conditioning on the Heat-induced Radioresistance in Primordial Germ Cells of the Fish Oryzias Latipes

Summary

Heat treatment (41°C, 30 min) given before γ-irradiation results in an increase in radiation resistance of primordial germ cells (PGCs) in Oryzias latipes at a mitotically inactive stage. This may be attributed to the appearance of a shoulder region on the dose–response curve, indicating an increased capacity to tolerate radiation damage. The radiation response curve is biphasic and the conversion of a radiosenstivie population to a less sensitive one as a result of heat treatment is suggested. When the PGCs were made thermotolerant by a ‘priming’ heat treatment (41°C, 10 min) a second heat treatment (41°C, 30 min) at 2 h interval did not induce resistance to radiation. A treatment of 41°C for 30 min without ‘priming’ gave a thermal reduction ratio of 4·6, whereas with ‘priming’ the ratio was 1·0. Thus heat induces radiation resistance in PGCs but this induction is suppressed under thermotolerant conditions.

• germ cells
• fish
• thermotolerance
• resistance