Bringing Life to a Biology Lab
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Proliferation and regeneration of adult mammalian neurons does not typically occur. However previous studies from this lab have demonstrated that eye drop application of the alpha7 nicotinic acetylcholine receptor agonist (α7 nAChR), PNU-282987, increases the number of retinal ganglion cells (RGCs) compared to controlled untreated conditions in adult rats and emerge from Muller glia. In this research documentary, we investigate when mitotically active cells first emerge from Muller glia in adult Long Evans rats in comparison to other animals, like chick and fish, which can regenerate adult neurons. We hypothesize that the nAChR agonist triggers growth of new neurons in adult rats using typical developmental processes. Experiments are discussed to test this hypothesis in a video format. This format was selected as an opportunity to familiarize the community with the culture of a college research lab. Groups of rats were selected to be used at three different time points: 12 hours, 24 hours, and 36 hours after treatment with PNU-282987. The α7 nAChR agonist was applied in phosphate buffered saline containing 1 mg/ml bromodeoxyuridine (BrdU) as eye drops to label mitotically active cells. Once eye drop treatments were completed, animals were sacrificed, retinas were removed and immunostained with an antibody against BrdU and proliferating cell nuclear antigen (PCNA) to assay S-phase completion or cell cycle reentry respectively. After immunocytochemical processing, retinas were sectioned, mounted and viewed under a Nikon confocal microscope. The results demonstrated that the early growth pattern for regeneration in adult rat retinas matched that of avian and fish; in that PCNA positive cells were identified first in the inner nuclear layer (INL) of the retina at 12 hours, and found in both INL and outer nuclear layer (ONL) of the rats at 24 and 36 hours. BrdU cells were only found in the ONL after the 36 hour treatment. These results provide insight into the mechanism of α7 nAChR agonist-induced regeneration in adult mammals and suggest that induced growth corresponds to a normal growth pattern found in animals capable of adult regeneration. This video also functions to show the process of research in a biological sciences lab, display what scientist do in times of difficulty, and introduces the relationships between people that form the community of the lab.
Bach, Harrison, "Bringing Life to a Biology Lab" (2017). Honors Theses. 2803.
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