On the biological effects of high background radioactivity: studies on Tradescantia grown in radioactive monazite sand

Tradescantia, clone 02, plants were grown in garden soil and were exposed to low level external radiations ranging from 0.08 mR/hr to 1.3 mR/hr or were raised in radioactive monazite sand cultures. In the experiment on external exposure alone, one group of plants was irradiated from transplanting while another group was irradiated from flowering. The occurrence of somatic mutations in the staminal hairs was recorded from flowering, for a period of over sixty days. After the specified period of growth, the plants from the monazite cultures and control were sacrificed and assayed for the absorbed radionuclides, especially for the alpha emitters. The radionuclide content in the plant body did not show a direct relation with the amount of monazite in the cultures. It appears that the contribution from the absorbed radionuclides is much more important in the production of biological damage than external irradiation alone

Microspectrophotometric studies on the pigments in vivo of single algal cells-I. Pigments of Chlorella Pyrenoidosa

The pigments in vivo of single cells of Chlorella pyrenoidosa were studied by the microspectrophotometric technique. An accessory recording the first derivative of absorption was used to obtain fine resolution and enhanced accuracy. The results suggest that there are several long-wavelength components of Chl a in vivo. In addition, there seem to be four short-wave forms of Chl a. It is also likely that Chl b exists in vivo in two different forms. The existence of all these forms was demonstrated at room temperature

Frequency of polyploid cells in the bone marrow of rats fed irradiated wheat

Diets containing different proportions of non-irradiated or irradiated wheat were fed to Wistar rats for 1 or 6 wk. Cytological analysis of the bone marrow showed no significant difference in the frequency of polyploid cells in the rats fed non-irradiated or irradiated wheat diets, even when the treated wheat was fed to the rats within 24 hr of irradiation

Derivative microspectrophotometry of single cells in vivo

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A study of reactions of N-ethyl malaeimide with cellular fractions during radiosensitization of E. coli B/R

E. coli B/r cells γ-irradiated under anoxic conditions and in the presence of NEM showed enhanced damage in terms of their colony-forming ability. Irradiation leads to binding of NEM with cellular macromolecules, particularly proteins. Binding occurs to all amino acid residues. In vitro irradiation of bovine serum albumin in aqueous solution has confirmed this. A reaction between NEM and amino acid radical has been implicated. The binding of NEM with cellular proteins may lead to inactivation of enzymes involved in post-irradiation biochemical processes giving rise to enhanced damage. NEM also reacts with amino acids in the absence of radiation, which may partly explain the residual sensitization noticed in cells treated with NEM. Part of the sensitizing effect of NEM has been shown to be due to its electron affinic property