Description and microbial characterization of bald sea urchin disease and spotting disease in the purple sea urchin

Bald sea urchin disease (BSUD) has been described for a variety of sea urchin species across many locations. The disease is characterized by spine loss and in some cases, discrete lesions. A similar, but separate disease, called spotting disease, has also been described for a variety of sea urchin species, and is characterized by discrete lesions on the body surface composed of discolored necrotic tissue that cause the loss of all surface appendages within the lesioned area. Discrete lesions are described for both BSUD and spotting disease, leading to confusions in distinguishing the two diseases. Previous studies investigating both BSUD and spotting disease have focused on identifying the underlying causative agents, which have proven to be a wide array of pathogenic bacteria that vary based on ocean location and species. In our aquaria, we had sea urchins that contracted BSUD and spotting disease separately. Our sea urchins are housed in a closed aquarium system, therefore, we were able to make direct comparisons between diseased and healthy sea urchins for both diseases. First, we aimed to characterize the BSUD infection by investigating the global surface microbiome of sea urchins infected with BSUD and after their recovery to identify changes to the microbiome associated with the disease. Secondly, we investigated the spotting disease infection by characterizing the global surface microbiome and the microbiome of various tissues. We collected samples, isolated the genomic DNA, and sequenced the V3-V4 region of the 16S rRNA gene. Results show that the global surface microbiome for sea urchins infected with BSUD undergoes significant shifts as they recover from disease. Many taxa are associated with the pathogenic microbiome, suggesting that the BSUD infection is likely the result of an altered microbial community. For the spotting disease investigation, results show that the lesions are composed mainly of Arcobacter and Vibrio, and that the bacteria in the lesions are also present in the tissues of healthy sea urchins, which suggests that the pathogenic bacteria that cause spotting disease may be present normally in sea urchin tissues. Finally, we show that BSUD and spotting disease are separate diseases with distinct symptoms and are associated with distinct microbiomes.

Author

• Shaw, Chloe

Language

• en

Keyword

• Echinoderm
• 16S gene sequence
• Microbiome
• Infection
• Strongylocentrotus purpuratus

Date created

• 2023

Type of Work

• Master's Thesis

License

• All rights reserved

Rights statement

• In Copyright

GW Unit

• Biological Sciences

Degree

• M.S.

Advisor

• Saw, Jimmy
• Smith, L. Courtney

Committee Member(s)

• Smith, L. Courtney
• Saw, Jimmy
• Eleftherianos, Ioannis

Persistent URL

•  https://scholarspace.library.gwu.edu/etd/gq67js05d