DESOXYRIBONUCLEIC ACID REPLICATION OF AUTOSOMAL HETEROCHROMATIN

The interphase nuclei of tissues of various origin of the European hedgehog display several very large chromocenters. They represent an appropriate material for the study of heterochromatin. Using 3H-thymidine autoradiography in cultures of hedgehog tissues, an autosomal origin of heterochromatin bodies is assumed. The results presented show that 1. 1. Autosomal heterochromatin synthesizes DNA in the condensed state. 2. 2. The replication of the DNA of autosomal heterochromatin exceeds considerably in time the replication of euchromatin. Thus, for a very extended terminal stage the heterochromatin is still found in replication. 3. 3. Within the overall context of asynchrony of DNA replication the autosomal and the sexchromosomal heterochromatin exhibit a nearly synchronous replication behaviour. The particular case of the European hedgehog provides clues for the assumption of genetic inactivation of the autosomal heterochromatin. © 1969.