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Nuclear matrices containing residual DNA were isolated from chicken erythrocytes after extraction of purified nuclei with buffered 2 M NaCl. After further purification of this residual DNA, it was found to contain high concentrations of beta-globin gene sequences as assayed by dot hybridization with 32P-labeled nick-translated pHB1001. Electron microscopy of a random sample of this residual DNA fraction shows the DNA to be intimately associated with protein at various intervals. A hypothesis for enrichment of active genes in residual DNA from purified chromatin or in nuclear matrix DNA is also discussed.

In the present studies, no porphyrins were found in the lunar surface fines collected from the Sea of Tranquillity by the Apollo 11 mission, from the Ocean of Storms by the Apollo 12 mission, and from the nonmare Fra Mauro Formation by the Apollo 14 expedition under the conditions in which porphyrins would have been detected had they been present in amounts as small as 10−14mole.