MACROPHAGE-MELANOCYTE HETEROKARYONS

Abstract

Mouse peritoneal macrophages, which do not synthesize DNA in vitro, were fused with melanocytes, a mouse cell strain which proliferates rapidly in vitro. DNA synthesis was induced in macrophage nuclei 2–3 hr after fusion and occurred irrespective of the number of macrophage nuclei present per melanocyte nucleus in each heterokaryon. 50–80% of macrophage nuclei initiated DNA synthesis in the 3–7 hr period after fusion. The activation of most 11–12-day chick red cell nuclei in melanocyte cytoplasm took longer than 10 hr. The lag before DNA synthesis may reflect the heterochromatin content of each nucleus.