Anna Mannini

Timing of Sex Chromosome Replication in Somatic and Germ-Line Cells of the Mouse and the Rat

Timing differences of the G2 periods were found among bone marrow cells labelled with 3H-thymidine in vivo , cultured kidney cells labelled in vitro<

KARYOTYPIC CLONAL EVOLUTION IN A CYSTIC ADENOMA OF THE OVARY

Abstract Short-term culture of cells from a cystic adenoma of the ovary removed from a 66-year-old woman, revealed normal cells, cells with a supernumerary C chromosome, and cells with two apparently similar C chromosomes. This was interpreted as evidence of clonal evolution, firstly by acquisition of a supernumerary chromosome followed by its occasional duplication leading to a second clone with 48 chromosomes. The chromosomal finding and the histological appearance of the tumour agree in indicating that this case illustrates the cytogenetic basis for the beginning of an evolution towards malignancy.

Incorporation of tritium-labelled actinomycin in a human cell line.

Abstract Autoradiography of cells of the EUE line cultured in vitro revealed preforential location of tritium-labelled actinomycin A1 and D on the nucleus and on the chromosomes. Uptake of 3H-actinomycin D by cell monolayers was, at the maximum, of the order of 4 per cent of the total radioactivity supplied to the cultures. Reproductive performance of the cells exposed to low doses of actinomycin D was studied by estimating total growth in monolayers, plating efficiency of single cells and mean number of cells in colonies derived from single cells. It was found that inhibition of clonal growth is more evident when actinomycin is given during the lag period after plating than when given at the beginning of the exponential growth. The hypothesis is made that addition of actinomycin at the beginning of the growth phase permitted synthesis of enough messenger-RNA to direct further cell division. It was confirmed that the first visible morphological changes induced by actinomycin are those affecting the nucleolar system. Actinomycin produced extensive chromosome breakage.