. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 398 THEO. M. KONIJN AND KENNETH B. RAPER plated on non-nutrient agar and incubated in constant light, constant darkness, and with initial dark periods of 4, 6 or 8 hours followed by light. The myxamoebae grown in the light aggregated earlier than the cells grown in darkness (Fig. 6). It" the light- and dark-grown cells were mixed in a ratio of 1:1 the time of aggrega- tion was intermediate between that of the light and the dark controls, but closer to that of the light-grown myxamoebae. Even if only \Q% of the myxamoeba
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 398 THEO. M. KONIJN AND KENNETH B. RAPER plated on non-nutrient agar and incubated in constant light, constant darkness, and with initial dark periods of 4, 6 or 8 hours followed by light. The myxamoebae grown in the light aggregated earlier than the cells grown in darkness (Fig. 6). It" the light- and dark-grown cells were mixed in a ratio of 1:1 the time of aggrega- tion was intermediate between that of the light and the dark controls, but closer to that of the light-grown myxamoebae. Even if only \Q% of the myxamoebae were. L 4D-L 6D-L 8D-L D Light Conditions Preceding Aggregation FIGURE 6. The influence of different light conditions on the time of aggregation in Dictyo- stelium discoideum, NC-4(H), in light-grown and in dark-grown myxamoebae and in mixtures of the two; myxamoebae grown in liquid shaken culture. Data represent averages for 3 experiments in each case. Populations tested: O: Cells grown in the light; (j: Light- and dark-grown cells in a ratio of 1:1; <w Light- and dark-grown cells in a ratio of 1:10; 9 Cells grown in darkness. Patterns of incubation: L: Continuous light; 4O-L: 4 hours dark followed by light; 6D-L: 6 hours dark followed by light; 8D-L: 8 hours dark followed by light; D: Continuous dark. (The two lower curves are drawn with breaks at 3L-D to reflect data obtained in earlier experiments. See Figure 3.) grown in the light, they still reduced the time of aggregation compared with pure populations of dark-grown cells. DISCUSSION Two striking features of this study are (1 ) the dependence ot the onset of aggregation on the prevailing light conditions, and ( 2 ) the different effects ot altered light conditions on different species and even in different strains of the same species. After deposition of the centrifuged cells, constant light was optimal for aggrega- tion in most species, \\hile an increasing dark period gradually delayed the occur- rence of aggregat
Size: 1890px × 1322px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
