Stimulation of DNA synthesis by ouabain and concanavalin A in cultures of embryonic neural retina cells.

Ouabain and concanavalin A, agents which bind to specific sites in the cell membrane, stimulate DNA synthesis and cell replication in monolayer cultures of neural retina cells from late chick embryos. The results suggest a relationship between control of retina cell replication and properties of the cell membrane. The experiments involved measurements of 3H-thymidine incorporation in primary monolayer cultures (24-48h) of retina cells from embryos of different ages. Stimulation by ouabain was greatest in cells from 14-day embryos, and its magnitude was similar to that elicited in these cell cultures by concanavalin A. Simultaneous treatment of 14-day retina cells with both agents resulted in a greater than additive stimulation of DNA synthesis. Our results demonstrated that, although during normal embryogenesis cell replication in the neural retina has virtually ceased by day 14 of development, some cells retained a capacity for mitogenesis when exposed to conditions such as provided in these experiments. By autoradiography the responding cells were identified as large epithelioid retina cells (LER cells). Under optimal conditions of simultaneous treatment with ouabain and Con A about 20% of the LER cells showed stimulation of DNA synthesis. The nature of LER cells and other aspects of our findings are discussed.