Table II.
Effects of exogenous polyamines on ODC activity in C. reinhardtii cells
| Polyamine | Concentration | ODC Activity | Student's t Test |
|---|---|---|---|
| mmol L−1 | % | ||
| – | – | 100.0 | – |
| Putrescine | 0.05 | 98.0 ± 3.4 | Nonsignificant |
| Putrescine | 0.10 | 97.1 ± 3.2 | Nonsignificant |
| Putrescine | 0.20 | 91.4 ± 7.6 | P < 0.05 |
| Putrescine | 0.50 | 82.5 ± 10.2 | P < 0.005 |
| Putrescine | 0.75 | 69.8 ± 13.1 | P < 0.0005 |
| Putrescine | 1.00 | 62.4 ± 6.9 | P < 0.0001 |
| Spermidine | 0.02 | 78.1 ± 16.7 | P < 0.005 |
| Spermidine | 0.05 | 61.3 ± 12.3 | P < 0.0005 |
| Spermidine | 0.07 | 50.9 ± 10.5 | P < 0.0001 |
| Spermidine | 0.10 | 44.7 ± 5.9 | P < 0.0001 |
| Spermine | 0.02 | 79.5 ± 18.4 | P < 0.025 |
| Spermine | 0.05 | 67.1 ± 16.3 | P < 0.00025 |
| Spermine | 0.07 | 54.7 ± 9.8 | P < 0.0001 |
| Spermine | 0.10 | 48.2 ± 5.3 | P < 0.0001 |
Cultures of the wall-deficient strain C. reinhardtii cw-15 (5 L) were grown under a 14-h light/10-h dark regime to a cell density of 0.5 to 1.0 × 106 cells mL−1. At the day of the experiment, 200-mL aliquots were taken from these cultures 8 h after onset of illumination and further incubated in the light in the presence of different concentrations of putrescine, spermidine, and spermine, respectively. After 5 h, cells were harvested by centrifugation and cell lysates prepared and analyzed for ODC activity and protein as described in “Materials and Methods.” Specific ODC activities are shown as percentage of the maximal activity of each experiment. Mean values of five separate experiments ± sd are given. P values were calculated by Student's t test.