Total Protein to DNA Ratio in 2C Nuclei of Dry Seed Meristems in Relation to Chromosome and Chromatid Aberrations Induced By X-Irradiation

Abstract

SUMMARYTotal nuclear protein content has been determined in G1 cells (2C DNA content) of embryonic meristems in dry seeds in two groups of species: i) those having meristems composed exclusively of G1 cells, which react to X-rays with chromosome (B″) aberrations (Allium cepa, Heliantus annuus, Pinus pinea) and ii) those having meristems composed of both 2C (G1) and 4C (G2) cells in different proportions and in which part of G1 cells react to X-rays with chromatid (B') aberrations (Vicia faba, Triticum durum, Triticum dicoccum and Aegilops longissima).In species of i) nuclear protein content in G1 cells was rather constant, while in species of group ii) a great variability of total nuclear protein content in G1 cells was detected.The hypothesis is advanced that the protein moiety of chromosomes rather than changes in the DNA molecule may be responsible for the transition from chromosome to chromatid aberration in irradiated G1 cells.