Many ultraviolet-A (UVA)-induced biochemical
and physiological changes are valid as
biomarkers using aquatic species for detection of the
degree of stress. Changes in the concentration and
activities of enzymes, such as glucose-6-phosphate
dehyderogenase (G6PDH), lactate dehyderogenase
(LDH), DNA damage and lipid peroxidation (LPO),
can be used as biomarkers to identify possible
environmental contamination in fish. This study
aimed to investigate the impact of UVA on the
activity of the selected enzymes, DNA damage and
LPO during early developmental stages of the African
catfish Clarias gariepinus. Embryo hemogenates were
used for measurements of G6PDH, LDH, DNA
damage and LPO concentrations and activities spectrophotometrically
at 37C. The normal ontogenetic
variations in enzyme activities, DNA damage and
LPO of the early developmental stages (24–168
h-PFS; hours-post fertilization stage) were studied.
There was a significant decrease in the activity of
G6PDH till 120 h-PFS. Then after 120 h-PFS, the
activity of such enzymes insignificantly increased
toward higher stages. The LDH activity was recorded
with a pattern of decrease till 96 h-PFS, followed by a
significant increase toward 168 h-PFS. The polynomial
pattern of variations in DNA damage and LPO
was also evident. The patterns of the enzyme activities,
corresponding DNA damage and LPO of the
early ontogenetic stages under the influence of three
different UVA doses (15, 30 and 60 min), were
recorded. The pattern of variations in G6PDH activity
in UVA-induced groups was similar to that of the
control group with variation in the magnitude of such
activity. In all treated groups, LDH activity decreased
till 96 h-PFS, then increased till 168 h-PFS. Within
each of the embryonic stages, the increase in UVA led
to a significant increase in DNA damage. A significant
increase in lipid peroxidation under UVA doses was
recorded. The variability in number and molecular
weight of proteins under exposure to UVA was
evident, reflecting some of the genetic and transcriptional
changes during exposure and development.