Discipline: Biological Sciences
Subcategory: Cell and Molecular Biology
Victor Gipson II - University of Georgia
Co-Author(s): Dr. Vladimir Mashanov, University of North Florida, Jacksonville, FL
Many organisms have an impressive ability to regenerate injured body parts. Regeneration phenomena are diverse and can involve various levels of biological regeneration ranging from large body parts and appendages, such as whole-arm regrowth in a brittle star, to the replacement of individual skin cells in humans. Even though humans can regenerate, the overall regeneration capability in our species is quite limited compared to that of some invertebrates. For example, humans do not repair injuries to their central nervous system (CNS). When the spinal cord is injured, there is currently no way to restore it back to its original form and function.
There are invertebrates that have the ability to completely regenerate major injuries to their nervous system. One such organism is the sea cucumber, Sclerodactyla briareus, from the phylum Echinodermata. It completely regrows its radial nerve cord in about four or five weeks. The overall goal of this project is to analyze the histological structure of the radial nerve cord at different time points post-injury. Understanding the regeneration process in the S. briareus CNS may give us insight as to how humans may be capable of this as well.
The mid-ventral radial nerve cords in adult individuals were injured through a complete perforating injury of the ventral body wall at the mid-body level. The injured sea cucumbers were then kept in aerated sea water for the duration of the experiments. At several time points post-injury (day 1, 5, 8, 12, 16, 22, 29), regenerating tissues were dissected out and processed for histological analysis. The tissue samples were fixed in paraformaldehyde and tissue processed for cryosectioning. Serial cryosections were collected on gelatin-covered slides and stained with hematoxylin and eosin. The slides were viewed and photographed using an Olympus compound microscope equipped with a digital camera using bright field settings. The digital micrographs were adjusted for brightness and contrast and then collated together using Fiji and Gimp imaging processing software.
On day 1, the lesioned ends of the radial nerve cords were still exposed into the coelomic cavity. On day 5, the radial nerve cord showed the earliest signs of tissue reorganization and growth at the wound surface. On day 16, the two rudiments from either side of the wound have grown and reconnected. Day 29 shows almost a complete restoration of the original histological structure. This project allowed us to choose the time points in regeneration at which to analyze the differential gene expression in sea cucumber regeneration in a subsequent project.
References: Kille, Frank R. ‘Regeneration in Thyone briareus Lesueur following induced autotomy.’ The Biological Bulletin 69.1 (1935): 82-108.
Funder Acknowledgement(s): This project was funded by the National Science Foundation REU Grant OCE-1560213.
Faculty Advisor: Dr. Vladimir Mashanov, firstname.lastname@example.org
Role: I conducted all of the research since this was my REU project over the summer. I was under the wing of Dr. Vladimir Mashanov throughout and he helped guide me.