Biology Reference
In-Depth Information
Fig. 6.1
(
a
) Total activities
of superoxide dismutase
(SOD) in individuals of
Desmarestia anceps
collected
from 5.5, 9.0, and 13.5 m
water depth before UV
exposure. Activities were
fitted according to a
logarithmical function.
(
b
) Changes of SOD activities
after 4 h of exposure to PAR
alone (control,
dotted
columns
), PAR + UV-A
(
grey columns
), and
PAR + UV-A + UV-B
(black columns) in
comparison to initial SOD
activities before UV exposure
(
white columns
). Error bars
characterize standard
deviations. The
asterisks
represent statistical
differences between SOD
activities of individuals from
different depths (
a
) or light
treatments (
b).
Note that the
SOD activities are plotted
logarithmically
SOD activity (U mg
-1
)
10
2
10
3
10
4
0
a
2
4
6
8
10
12
y = 7508 - 6401.1log(x)
R
2
= 0.99981
14
10
4
b
10
3
10
2
5.5
9.1
13.6
Water depth (m)
individuals from the deepest position tested (13.5 m) revealed significantly lower
SOD activities of 241
184 Units mg protein
1
. SOD activities of
D. anceps
from
each water depth did not change in the course of the 4 h exposure to either UV-A or
UV-B radiation compared to samples under PAR alone (Fig.
6.1b
).
Thus, the results presented suggest that
D. anceps
' capacity to detoxify the
superoxide radical formed under conditions of environmental stress (here: artificial
UV radiation) is strongly related to environmental variability, i.e., according to
original growth depth: high SOD activities may protect shallow water individuals
of
D. anceps
efficiently against ROS induced by environmental stress. The intra-
specific adjustment of SOD activity thus seems to represent a crucial mechanism of
acclimation along environmental gradients. However, although UV-B radiation is
regarded to be an important factor determining macroalgal vertical distribution
