Exposure to ultraviolet radiation has been associated with variety effects in many organisms ranging
from molecular and tissue damage to population level effects. The exposure of embryos of the catfish, Clarias
gariepinus (Burchell, 1822) to 366 nm UVA at different doses 15, 30 and 60 min resulted in the hatching
time delayed to 29 h-post-fertilization stage (29 h-PFS) in comparison with normal hatching time of
22 h-PFS at 29 C. In embryos exposed to 15 min/UVA, 30 min/UVA and 60 min/UVA the total percentage
of hatched embryos/fertilized eggs were 90%, 89% and 85%, respectively, while in control was 95% at 29 h-
PFS. The total percentage of mortality/ hatched embryos were (1–14)%, (2–22)%, (2–23)% and (3–40)% for
control, 15 min, 30 min and 60 min groups, respectively, at 40 h-PFS. Also as a result some morphological
malformations; (yolk sac oedema, body curvature, fin blistering, and dwarfism) were revealed. These
destructive effects were also confirmed by histopathological changes in gills, eyes, intestinal tract, spinal
cord, notochord, liver, skin and kidney. The results confirm that exposure to UVA caused an exposure
time-dependent delay in hatching rate and reduced the percentage of the hatched embryos but the mortality
rate increased with increase of the exposure time to UVA.

Exposure to ultraviolet radiation has been associated with variety effects in many organisms ranging
from molecular and tissue damage to population level effects. The exposure of embryos of the catfish, Clarias
gariepinus (Burchell, 1822) to 366 nm UVA at different doses 15, 30 and 60 min resulted in the hatching
time delayed to 29 h-post-fertilization stage (29 h-PFS) in comparison with normal hatching time of
22 h-PFS at 29 C. In embryos exposed to 15 min/UVA, 30 min/UVA and 60 min/UVA the total percentage
of hatched embryos/fertilized eggs were 90%, 89% and 85%, respectively, while in control was 95% at 29 h-
PFS. The total percentage of mortality/ hatched embryos were (1–14)%, (2–22)%, (2–23)% and (3–40)% for
control, 15 min, 30 min and 60 min groups, respectively, at 40 h-PFS. Also as a result some morphological
malformations; (yolk sac oedema, body curvature, fin blistering, and dwarfism) were revealed. These
destructive effects were also confirmed by histopathological changes in gills, eyes, intestinal tract, spinal
cord, notochord, liver, skin and kidney. The results confirm that exposure to UVA caused an exposure
time-dependent delay in hatching rate and reduced the percentage of the hatched embryos but the mortality
rate increased with increase of the exposure time to UVA.

Exposure to ultraviolet radiation has been associated with variety effects in many organisms ranging
from molecular and tissue damage to population level effects. The exposure of embryos of the catfish, Clarias
gariepinus (Burchell, 1822) to 366 nm UVA at different doses 15, 30 and 60 min resulted in the hatching
time delayed to 29 h-post-fertilization stage (29 h-PFS) in comparison with normal hatching time of
22 h-PFS at 29 C. In embryos exposed to 15 min/UVA, 30 min/UVA and 60 min/UVA the total percentage
of hatched embryos/fertilized eggs were 90%, 89% and 85%, respectively, while in control was 95% at 29 h-
PFS. The total percentage of mortality/ hatched embryos were (1–14)%, (2–22)%, (2–23)% and (3–40)% for
control, 15 min, 30 min and 60 min groups, respectively, at 40 h-PFS. Also as a result some morphological
malformations; (yolk sac oedema, body curvature, fin blistering, and dwarfism) were revealed. These
destructive effects were also confirmed by histopathological changes in gills, eyes, intestinal tract, spinal
cord, notochord, liver, skin and kidney. The results confirm that exposure to UVA caused an exposure
time-dependent delay in hatching rate and reduced the percentage of the hatched embryos but the mortality
rate increased with increase of the exposure time to UVA.

The present study aimed to elucidate the negative impacts of UVA on some biochemical and hematological
variables of the economically important African catfish, Clarias gariepinus and investigates the putative
role of quince (Cydonia oblonga Miller) leaf extract in protection and/or alleviation of such negative
impacts. Changes in the hematological and blood biochemical values often reflect alteration of physiological
state. Blood parameters can be useful for the measurement of physiological disturbances in stressed
fish and thus provide information about the level of damage in the fish. We found a significant (P < 0.05)
decrease in the red blood cell counts, hemoglobin and hematocrit in the groups exposed to UVA compared
to the control groups. Exposure to UVA induced marked red cell shrinkage (increased mean cell
hemoglobin concentration) and showed an elevation in mean cell volume and mean cell hemoglobin
in the blood of the exposed fish compared to the control. A significant (P < 0.05) reduction in the total
white blood cells was recorded in the exposed fish compared to the control. The biochemical parameters
(blood glucose, total plasma protein, blood cholesterol, plasma creatinine, aspartic amino transferase and
alanine amino transferase) exhibited a significant increase in the blood of fish exposed to UVA.
Methanolic extract of quince leaf before ripening of the fruits was analyzed by GC/MS. To investigate
the biological impact of this extract and its biologically active components, this extract was tested for
its putative role in alleviation of UVA effect on catfish. Quince leaf extract had the ability to prevent
hematotoxic stress induced by UVA and resulted in enhancement of the immune system of catfish represented
by significant (P < 0.05) increase in the number of white blood cells and lymphocytes of the catfish.
Quince extract also protected the red blood cells from UVA damage. To our knowledge this is the first
report of the effect of quince leaf extract on an aquatic organism.

The present study aimed to elucidate the negative impacts of UVA on some biochemical and hematological
variables of the economically important African catfish, Clarias gariepinus and investigates the putative
role of quince (Cydonia oblonga Miller) leaf extract in protection and/or alleviation of such negative
impacts. Changes in the hematological and blood biochemical values often reflect alteration of physiological
state. Blood parameters can be useful for the measurement of physiological disturbances in stressed
fish and thus provide information about the level of damage in the fish. We found a significant (P < 0.05)
decrease in the red blood cell counts, hemoglobin and hematocrit in the groups exposed to UVA compared
to the control groups. Exposure to UVA induced marked red cell shrinkage (increased mean cell
hemoglobin concentration) and showed an elevation in mean cell volume and mean cell hemoglobin
in the blood of the exposed fish compared to the control. A significant (P < 0.05) reduction in the total
white blood cells was recorded in the exposed fish compared to the control. The biochemical parameters
(blood glucose, total plasma protein, blood cholesterol, plasma creatinine, aspartic amino transferase and
alanine amino transferase) exhibited a significant increase in the blood of fish exposed to UVA.
Methanolic extract of quince leaf before ripening of the fruits was analyzed by GC/MS. To investigate
the biological impact of this extract and its biologically active components, this extract was tested for
its putative role in alleviation of UVA effect on catfish. Quince leaf extract had the ability to prevent
hematotoxic stress induced by UVA and resulted in enhancement of the immune system of catfish represented
by significant (P < 0.05) increase in the number of white blood cells and lymphocytes of the catfish.
Quince extract also protected the red blood cells from UVA damage. To our knowledge this is the first
report of the effect of quince leaf extract on an aquatic organism.

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.