Meeting Abstract
Xenopus laevis is a model system widely used to investigate metamorphosis, tail regeneration and regression. Aspects related to tail regeneration and regression are among the most interesting as both the processes are opposed to each other. In the present study we have investigated the role of reactive oxygen species (ROS) with emphasis on nitric oxide (NO) in both these processes. Our results on in situ staining for ROS show that during early stages of metamorphosis, tail fin showed presence of ROS in moderate amount reaching its peak in climax period. Just before the tail starts regressing, large amount of ROS were noted especially in the epidermal cells of the fin. Further increase in ROS in fin epidermal cells occurs once the regression had begun. In situ staining for mitochondrial derived NO in tail showed an increasing trend with metamorphic progress. Crucial role of fin epidermis in the process of tail regression is well established. Western blot results show decrease in expression of SOD and catalase as metamorphosis progressed indicative of lowered antioxidant defenses. In contrast, staining for ROS in the regenerate is much stronger than NO. Western blot results show increase in SOD but steady expression for catalase in regenerating tail compared to un-amputated tail during different stages of metamorphosis. This indicates increase in hydrogen peroxide as a salient feature of regeneration. It is possible that high levels of super oxide and hydrogen peroxide may inactivate NO. Thus, it appears that ROS signaling is vital to both the processes which may modulate signaling but disparity in type of ROS produced characterize subtle differences between regression versus restoration of the tail.
