EFFECTS OF LEAD ON THE NUCLEAR REPETITIVE DNA OF THE MOSS FUNARIA-HYGROMETRICA (BRYOPHYTA)

funaria hygrometrica gametophytes were grown in in vitro controlled sy stems in the presence and absence of lead. Their nuclear genomes were then analyzed directly in situ with A+T and G+C specific fluorochromes , image analysis and statistical data elaboration by specific software , in order to characterize the different fractions of repetitive DNA. The results reveal qualitative and quantitative differences between th e nuclear genomes of lead-stressed and unstressed individuals. These d ifferences seem to consist of a significant increase in G+C rich repet itive DNA sequences in nuclei of the stressed individuals. These seque nces form well defined agglomerates, generally situated adjacent to th e nucleolar region, which increase in both size and number in the pres ence of lead. Some hypotheses are discussed.