Experimentally induced bacterial hemolytic jaundice of yellowtail and oxidative stress

To elucidate whether yellowtail Seriola quinqueradiata experimentally infected with the jaundice-causing bacteria suffer from severe oxidative stress, hemoglobin level in the blood, malondialdehyde (MDA), alpha-tocopherol (alpha-Toc) levels in the liver and plasma, and phosphatidylcholine hydroperoxide (PCOOH) level in the liver of the fish were analyzed alter an intraperitoneal injection with the causative agent of bacterial hemolytic jaundice. The bacterial injection brought hemolysis and jaundice in the fish. The liver PCOOH and MDA levels and the plasma MDA level increased and the plasma alpha-Toc level decreased in the infected fish. These results suggest that yellowtail experimentally affected by the jaundice suffer from severe oxidative stress. We have recognized that severe oxidative stress led to induction of heme oxygenase catalyzing bilirubin synthesis in the liver of yellowtail. Therefore, we consider that the jaundice of yellow tail caused by the causative bacteria is due to the stimulation of bilirubin synthesis induced by severe oxidative stress.