Metaphase chromosome uptake by mammalian cells and cxpression of the genes transferred

Isolated metaphase chromosomes can be incorporated into mammalian cells. The genetic information thereby transferred, in the form of a chromosome, can be replicated and expressed in the recipient cell and its progeny, thus resulting in permanent genetic change. Whether this information transfer involves an intact chromosome or merely a fragment, which may be integrated into a host chromosome, has not yet been established. The possible implications of these findings for analysis of genetic linkage in somatic cells are discussed. Probable steps currently limiting the efficiency of this transfer process are also considered.O. W. McBRIDE, Laboratory of Biochemistry, National Cancer Institute, Bethesda , Maryland