Limb Regeneration in Daphnia magna is Associated with Distal Cellular Enrichment, but Not Affected by Fluoxetine Exposure.
Contamination of freshwater ecosystems can be caused from several factors, including pharmaceutical disposal into the environment. Fluoxetine is one of the many pharmaceuticals that may be affecting these ecosystems. This drug, brand name Prozac, is an antidepressant used to treat several disorders such as depression and obsessive-compulsive disorder. To further our understanding of these effects, Daphnia magna were exposed to environmentally-relevant levels of fluoxetine and studied its effects on cellular regeneration of the bifurcated segment of the antennae. It was hypothesized that the fluoxetine group will have faster cellular regeneration than the control group. Batch size of neonates was also examined, we predicted fluoxetine was would increase average batch size. This hypothesis was pursued by exposing animals to drug, severing the left antenna where it bifurcates, and measuring regeneration through imaging. The control group was acclimated in COMBO medium with Ankistrodesmus sp. for three days, whereas the exposed group also had fluoxetine (1.0 μg/L). After three days the surgeries were performed, images were obtained, and the Daphnia magna were placed in their appropriate conical tube. On the tenth day, the animals were fixed and imaged. Viable animals underwent staining for fluorescence (F-actin, membranes, DNA) imaging. The results were analyzed through ImageJ and excel. We found that regrowth for the control group was 0.48 and fluoxetine exposed was 0.12. The standard deviation was calculated to be ±0.36 for the control group and ±0.56 for the group exposed to fluoxetine. Finally, the standard error was 0.12 for the control and 0.23 for individuals exposed to fluoxetine. Regrowth did occur, but there was no significant difference between control and exposed groups. Fluorescence microscopy revealed distal cellular enrichment at the site of regeneration. Our results shed light on percent regrowth of the distal cellular enrichment of D. magna. Time and resources set limitations on findings, mortality number could have impacted results.