Sister-chromatid exchanges in Picea abies--a test for genotoxicity in forest trees

A genotoxicity test, based on the evaluation of sister-chromatid exchange frequencies, has been developed for the spruce fir. The basic frequency was 36.9 SCEs/cell. Mitomycin C treatment (MMC, 5 x 10(-6) M, 0.5 h) doubled the 'spontaneous' SCE frequency, maleic hydrazide treatment (MH, 5 x 10(-4) M, 0.5 h) increased it nearly 7-fold. This corresponds to data obtained previously for Vicia faba. Chromatid-type aberrations were induced by the same mutagens (MH, 5 x 10(-4) M, 0.5 h; MMC 2 x 10(-5) M, 1 h) or by triethylenemelamine (TEN, 2 x 10(-4) M, 0.5 h). MH treatment resulted in aberration yields comparable to those observed in Vicia faba, MMC and TEM were less efficient aberration inducers in P. abies. While SCEs may be counted for single chromosomes, for reliable evaluation of chromatid aberrations large numbers of complete and well spread metaphases have to be inspected.