Magdy E. Mahfouz, Mona M. Hegazi, Mohammed A. El-Magd and Enas A. Kasem
الملخص العربي
The strictly aquatic breathing Nile tilapia, Oreochromis niloticus is an extremely
hypoxia-tolerant fish. To augment our understanding of the effects of
hypoxia on anaerobic glycolysis in the Nile tilapia, we studied the effect of
short-term for 1 day (trial 1) and long-term for 30 days (trial 2) hypoxia on a
selected glycolytic enzymes activity and mRNA expression in liver and white
muscle. The hypoxic oxygen concentrations used in the two trials were 2, 1,
and 0.5 mg O2 L−1 for comparison with a control normoxic group 8 mg O2
L−1. The activity of phosphofructokinase (PFK), pyruvate kinase (PK), and
lactate dehydrogenase (LDH) in liver and white muscle except liver LDH
decreased in trial 1 and increased in trial 2. Assessments of mRNA levels in
trial 1 revealed that PFK was downregulated and LDH was upregulated in
liver and white muscle, while PK fluctuated between upregulation in liver and
downregulation in white muscle. Meanwhile, PK and LDH were upregulated
while PFK was similar to control values in both tissues in trial 2. Comet
assay results demonstrated an increase in DNA damage that was directly
proportional to increasing hypoxic concentrations. This damage was more
pronounced in trial 1. This suggests that the Nile tilapia cope better with
long-term hypoxic conditions, possibly as an adaptive response.
محمد رزق ابو المجد الغنام | Mohammed Rizk Abu El-Magd El-Ghannam | 8896