Project description:SP cells in HL cell lines are characterized by up-regulation of genes related to TNF-alpha Signaling via NF-κB, Inflammatory Response and Hypoxia compared to the non-SP cells.
Project description:SP cells in HL cell lines are characterized by up-regulation of genes related to TNF-alpha Signaling via NF-κB, Inflammatory Response and Hypoxia compared to the non-SP cells.
Project description:To identify the respective roles of light and ROS in the photoinhibition process and detect a possible light-driven tolerance to oxidative stress, we compared the transcriptomic responses of Synechococcus sp. WH7803 acclimated to low (LL) or high light (HL) to oxidative stress, induced by hydrogen peroxide (H202) or methylviologen (MV). Cultures were acclimated during many generations to continuous low light (LL, 18 ?mol photons m-2 s-1, hereafter LL cells) and high light (HL, 250 ?mol photons m-2 s-1, hereafter HL cells) provided by Sylvania Daylight 58W/154 fluorescent bulbs. For all stress experiments performed in this study, exponentially growing cultures (1 to 3 x 107 cells mL-1), were split into subcultures and submitted to oxidative stress by addition of H2O2 or MV and harvested when PSII quantum yield fell to half of the initial value. For H2O2 experiments, this level of PSII photoinactivation was reached 2 h after submitting LL and HL cultures to 750 M and 25 M respectively. Because of the large divergence in dose and kinetics responses to MV between LL- and HL cells, it was not possible to find MV concentrations leading to 50 % decrease of quantum yield at the same time for both light acclimations. Thus, array analyses for MV were performed on HL and LL cultures incubated at the same MV concentration (50 M) but harvested once PSII quantum yield was halved, i.e. after 1 and 3.5 h of stress respectively. All hybridizations were performed on 4 independent biological replicates and using as reference sample a pool of RNA from all samples investigated in this study. Pairwise comparison were performed to analyze the stress induced by either H2O2 or MV on both LL- and HL cultures (i.e. LL-Ct vs. LL+MV, LL-Ct vs. LL+H2O2, HL-Ct vs. HL+MV, HL-Ct vs. HL+H2O2) as well as to compare the steady state acclimation to different light conditions (i.e. LL-Ct vs. HL-Ct).
