The cytophotometric analysis of cell fusion and zygote formation in the myxomycete Didymium iridis

Abstract

Microspectrophotometric and cytochemical examinations were made on zygotes formed from myxamoebae and warm cells of the Honduran 1-2A1 and Panamanian 2-7A8 isolates of the heterothallic myxomycete Didymium iridis. Quantitative measurements of the Feulgen-DNA nuclear reaction were made at predetermined time periods. The results of this investigation indicate a delay of approximately 45 minutes to 1 hour before sexual fusion occurs between myxamoebae and swarm cells. Maximum zygote formation occurs approximately 1 hour after the initiation of sexual fusion. Myxamoebae are also shown to form more zygotes than swarm cells an din shorter length of time. It is also shown that myxamoebae replicate their DNA than divide, possessing a high rate of mitotic activity, whereas swarm cells have a limited capacity to divide, synthesizing DNA then undergoing G2 arrest.