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Neutron and Roentgen-Ray Effects on Protein Content of Rat Intestine.--M. H. Ross AND J. O. ELY (Am..f. Roentgenol. Radium Therapy, 62: 718, 1949). A reduction in the amounts of tyrosine, tryptophane, arginine and nitrogen, which are important constituents of protein, is evidence of a reduction in the amount of protein after neutron and roentgen irradiation.
Cytochemical determinations of the total protein content in tissue sections was estimated through the study of the tyrosine and tryptophane ultraviolet absorption at the wavelength 3654 ~. The tyrosine and tryptophane content was markedly decreased in the crypts of Lieberkfihn 24 hr. after 600 r total body roentgen irradiation, but there was no significant change in the tyrosine and tryptophane content of the crypts of Lieberkfihn 24 hr. after 56 n total body neutron irradiation. A considerable decrease in the tyrosine and tryptophane content of the crypts of Lieberkfihn was found 24 hr. after 100 n or 200 n total body irradiation respectively.
The arginine content was found to decrease 24 hr. after 600 r or 200 n total body irradiation.
The percentage of nitrogen was not markedly changed in the acetone dried intestinal mucosa in irradiated or non-irradiated fasted animals. The amount of acetone-dried intestinal mucosa was significantly changed after 24 and 48 hr. in those animals irradiated with 200 n, but was not changed in those non-irradiated animals whose food had been restricted for the same periods of time. The calculated total nitrogen for the acetone-dried intestinal mucosa was found to be greatly decreased 24 and 48 hr. respectively after 200 n neutron radiation, but there was no significant reduction in non-irradiated fasted animals.
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Lack of Depolymerase Effect on Desoxyribonucleic Acid in Living Cells.-J. 0. ELY AND M. H. Ross (Science, 109: 367, April 8, 1949). Desoxyribonucleic acid depolymerase had been reported bq several investigators to remove the ultraviolet light absorbing constituents and the Feulgen stainable material
Highly polymerized ribonucleic acid has been prepared from calf and rat liver. The procedure involves the maintenance of the pH between 6 and 7, the precipitation of a nucleic acid-protein complex from the cytoplasmic extract according to the method of Volkin and Carter, heat denaturation of the pro