FIGURE LEGENDS
FIGURE 1. Effect of long-term stress acclimation on
partitioning of PSII (a) and PSI (b) in UWO 241 and SAG 49.72 grown
under control and long term stress conditions. ΦNO, non-regulated energy
dissipation; ΦNPQ, non-photochemical energy quenching; ΦPSII, PSII
quantum yield; ΦPSI, PSI quantum yield; ΦND, donor side limitation; ΦNA,
acceptor side limitation. C, Control; HL, High Light; LT, Low
Temperature; HS, High Salt. Values are means with standard deviations
(n=3). All parameters were measured at growth irradiance (see Table 1).
FIGURE 2. Capacity for nonphotochemical quenching in UWO 241
(UWO) and SAG 49.72 (SAG) grown under control and high stress
conditions. C, Control; HL, high light; LT, low temperature; HS, high
salt. Letters - a, statistical significance between control vs. stress
within one algal species; b, statistical significance between UWO 241
vs. SAG 49.72 when grown under same treatment (n=3; p<0.05).
FIGURE 3. 77K Chl a fluorescence emission spectra of the
mesophile SAG 49.72 (a) and the psychrophile UWO 241 (b) and acclimated
to control and long-term stress treatments. C, Control; HL, high light;
LT, low temperature; HS, high salt.
FIGURE 4. Photosystem I (P700) oxidation/reduction of the
mesophile SAG 49.72 and the psychrophile UWO 241 grown under control and
long-term stress conditions. a. Oxidation state of P700.
b. Re-reduction kinetics of P700+. P700oxidation/reduction was monitored in the presence of far red light.
Letters - a, statistical significance between control vs. stress within
one algal species; b, statistical significance between UWO 241 vs. SAG
49.72 when grown under same treatment (n=3; p<0.05). C,
Control; HL, high light; LT, low temperature; HS, high salt; ND, not
detectable.
FIGURE 5. Photosystem I oxidation/reduction kinetics in UWO 241
grown under control and long-term stress conditions.
P700 oxidation/reduction was monitored in the presence
of red actinic light following DCMU pretreatment. (a) Oxidation state of
P700. (b) Re-reduction kinetics of
P700+. Letters statistical significance between control
vs. stress (n=3; p<0.05). C, Control; HL, high light; LT, low
temperature; HS, high salt. (c) P700+ re-reduction kinetics.
FIGURE 6 . NPQ and CEF exhibit a linear relationship. C.
raudensis SAG 49.72 and C. sp. UWO241 grown under control and long-term
stress conditions. NPQ axis represents maximum NPQ values determined
from light response curves. CEF represents P700 re-reduction rates.
Dashed and solid lines show linear regression for all data points or
individual organisms, respectively (n=3 or 7-9 for NPQ and CEF,
respectively).
FIGURE 7. Activity of AsA-GSH pathway enzymes, ascorbate
peroxidase (APX, a) and glutathione reductase (GR, b) the mesophile SAG
49.72 and the psychrophile UWO 241 grown under control and long-term
stress conditions. Letters - a, statistical significance between control
vs. stress within one algal species; b, statistical significance between
UWO 241 vs. SAG 49.72 when grown under same treatment (n=3;
p<0.05). C, Control; HL= high light; LT, low temperature; HS,
high salt.
FIGURE 8. Photoinhibition and recovery in the mesophile SAG
49.72 and the psychrophile UWO 241. Cultures grown under control
conditions exposed to either high light (HL, 300 μmol
m-2s-1) or low temperature LT,
(2oC) short-term stress for 60 min then returned to
control conditions for 120 min to recover. (a) Percent photoinhibition
was determined by loss of photochemical ability
(FV/FM) relative to time zero. (b)
Photochemical quenching, qL. C. nonphotochemical quenching, ɸNPQ (n=3).
FIGURE 9. Production of reactive oxygen species in UWO 241 (P)
vs. SAG 49.72 (M) during short-term incubation in low temperature
(5oC) or high light (300 μmol
m-2s-1) stress. Algal samples were
incubated for 1 hour in the presence of NBT dye to detect superoxide.
Data is normalized to time 0. Letters - a, statistical significance
between control vs. stress within one algal species; b, statistical
significance between UWO 241 vs. SAG 49.72 when grown under same
treatment (n=3; p<0.05).
Table 1. Growth conditions for UWO 241 and SAG 49.72 used in
this study.