Abstract
Summary
(1) PNA was completely extracted from fixed sections of liver by 18 hours of treatment with 10% perchloric acid at 4°C. No significant quantity of DNA was removed by such treatment even after 93 hours of incubation. (2) The above treatment is inadequate to extract PNA completely from nerve cells. However, with formalin-fixed nerve tissue, 12 hours incubation in 10% perchloric acid at 20°C and 15 minutes at 37°C was found to effect complete extraction of PNA with no loss of DNA. (3) At higher temperatures of extraction, the margin of safety between complete removal of FN A and incipient extraction of DNA was much smaller. (4) Prolonged hardening of nervous tissue in 10% formalin rendered PNA resistant to extraction by perchloric acid. (5) Perchloric acid extraction of fixed sections of nervous tissue removed insignificant quantities of nerve cell protein. (6) Cell structure was unaltered by this extraction procedure. (7) This extraction procedure did not alter the E2537A of two tissues without PNA, skeletal muscle and ribonuclease-treated nerve cells. It was suggested that this procedure could be employed to provide tissue “blanks” in ultraviolet microabsorption spectroscopy for PNA in tissue sections.
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