Relationship between Nuclear Volumes, Chromosome Numbers, and Relative Radiosensitivities

Abstract

An inverse relationship between a volume estimated to be associated with interphase chromosomes and acute lethal exposure to x-or gamma radiation has been found in 16 plant species. The apparent differences in radiosensitivities found would seem spurious, since the estimated average energy absorbed in the nucleus per chromosome (3.6 x 10(6) ev) approaches a constant (variation less than fourfold) in spite of wide ranges of lethal exposures (0.6 to 75 kr), of nuclear volumes (43 to 1758 micro(3)), and of somatic chromosome numbers (6 to 136). The regression line obtained can be used to predict the radiosensitivities of other plant species if their nuclear volumes and chromosome numbers are known.

Radiation induced hormesis and its cytological evaluation in sunnhemp <i>Crotalaria juncea</i> L.

“…The sensitivity of ionizing radiation is directly proportional to the size of the cell nucleus or chromosome volume. The larger the chromosome volume the more sensitive the material is to radiation (Sparrow et al 1963). Lacking plant diversity and eventual erosion of genetic resources has given added impetus to the field of induced mutagenesis.…”

Gamma Radiation

“…Elements important in fission products entering the environment through fallout or waste disposal. Sparrow (1962), Sparrow and Evans (1961), Sparrow and Woodwell (1962), and Sparrow et al (1963) have demonstrated that sensitivity of ionizing radiation is directly proportional to the size of the cell nucleus or chromosome volume. The larger the chromosome volume the more sensitive the material is to radiation.…”

“…Sparrow (1962), Sparrow and Evans (1961), and Sparrow et al (1963) present detailed information on the relationship between nuclear volumes, chromosome numbers and relative radiosensitivity.…”

Use of Radiation and Isotopes in Insects

“…Apparently, neither DNA content, chromosome number, nor chromosome arm number can be responsible for the differences in radiosensitivity of cells (Jacquet & Leonard, 1983). Even thou, there is a relationship between the interphase nuclear volume and cell sensitivity to radiation, that is used in vertebrate animals and plants to predict their sensitivity to chronic 68 irradiation, which express that the larger the nuclear volume, the greater the sensitivity (Casarett, 1968;Sparrow et al, 1963). The radiosensitivity of the mitotically active reproductive cells has different sterilization and killing susceptibility regarding the developmental stage and the division phase.…”