SISTER-CHROMATID EXCHANGES IN CONIFEROUS FOREST TREES

A significant increase of the sister chromatid exchange (SCE) frequenc y is typical for mutagen-treated cells and widely considered as an ind icator of genotoxic environmental impacts. SCEs were studied in 3 wide spread gymnosperms: the spruce Picea abies, the pine Pinus sylvestris, and the larch Larix decidua, each with 2n=24 chromosomes. Unifilarly BrdUrd-substituted chromosomes revealed, by means of the fluorescent p lus Giemsa (FPG) technique, a basic SCE frequency of 36.9/cell in Pice a abies, 36.2/cell in Pinus sylvestris, and 27. 6/cell in Larix decidu a. Seedlings from damaged P. abies trees revealed significantly more S CEs/cell than seedlings from healthy trees of the same area.