Effect of inhibitors of protein synthesis and DNA replication on the induction of proteolytic activities, caspase-like activities and cell death in the unicellular chlorophyte Dunaliella tertiolecta

Figures & data

Fig. 1. Variation of PS II optimum quantum yield (F_v/F_m) under light deprivation in Dunaliella tertiolecta. Cultures were placed in darkness immediately after the day 0 measurement (culture in light). Control culture (•); culture containing 100 μM MMC (○); culture containing 100 μM CHX (▾); culture containing 1500 μM CAP (▿); culture containing 100 μM CHX + 1500 μM CAP (▪). Symbols are means of duplicate measurements and error bars indicate standard deviations. * indicates significant F-value in 1-way ANOVA for each sample time.

Fig. 2. Cell density of Dunaliella tertiolecta under light deprivation. Cultures were placed in darkness immediately after the day 0 measurement (culture in light). Symbols are means of triplicate measurements and error bars indicate standard deviations.

Fig. 3. Casein zymograms of protease activities from Dunaliella tertiolecta detected after separation of proteins by using 10% native PAGE under non-denaturing conditions. (A) in presence and absence of CHX and/or CAP. CBD: control culture (-CHX-CAP) before darkness; CAD: control culture (-CHX-CAP) after 6 days in darkness; CHX 6d: culture + CHX after 6 days in darkness; CAP 6d: culture + CAP after 6 days in darkness; CAP + CHX 6d: culture + CAP + CHX after 6 days in darkness. (B) in presence and absence of MMC. CBD: control culture (-MMC) before darkness; CAD: control culture (-MMC) after 6 days in darkness; MMC 6d: culture + MMC after 6 days in darkness.

Fig. 4. Total protein composition from Dunaliella tertiolecta detected after separation in a 15% gradient SDS – PAGE and stained with Coomasie blue R 250. (A) in presence and absence of CHX or MMC. (B) in presence and absence of CAP and CAP + CHX. Abbreviations as in Fig. 3.

Fig. 5. Caspase-like activity in Dunaliella tertiolecta. Caspase-like activity was measured as hydrolysis of 7-amino-4-fluoromethyl coumarin-labelled substrates specific for caspases 9 (LEHD, panel A) and 3 (DEVD, panel B) and before and after 6 d dark in the presence and absence of CHX, MMC, CAP and CAP + CHX. Abbreviations as in Fig. 3. Bars are means of triplicate measurements and error bars represent standard deviations. U is the activity of one unit of enzyme defined as 1 μmol of AFC-labelled substrate hydrolysed per minute. * indicate significant differences between each treatment and the control culture in darkness (Tukey test).