DIFFERENTIAL RESPONSES TO NEUTRAL RED UPTAKE OF MATING TYPE-I AND MATING TYPE-II CELLS IN PARAMECIUM-PRIMAURELIA .2. CHANGE IN THE MACRONUCLEAR DNA CONTENT

The cytofluorometric measurements of the macronuclear DNA content of reactive split cells stained with neutral red solution reveal that the dye affects differently the mating type I (stocks 90 and P) and the mating type II (stock 90) cells of Paramecium primaurelia. In fact, unlike mating type I populations, the mating type II stained cells show a macronuclear Feulgen-DNA content significantly higher than that of the unstained population. It can be assumed that the differential effect of neutral red is related to a different storage of dye in the two mating types cells. These results give further evidence that the expression of the two mating types, related to the mode of clonal growth, is linked to with cell conditions which are found to be different.