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dc.contributor.advisorGilmore, Thomas D.en_US
dc.contributor.authorMansfield, Katelyn Marieen_US
dc.date.accessioned2019-12-16T20:00:27Z
dc.date.available2019-12-16T20:00:27Z
dc.date.issued2019
dc.identifier.urihttps://hdl.handle.net/2144/38976
dc.description.abstractMany organisms form mutually beneficial, symbiotic partnerships with other organisms. Corals and sea anemones undergo mutualistic symbioses with photosynthetic algae of the family Symbiodiniaceae, and these partnerships are key for the viability of coral reef ecosystems. Cnidarian-Symbiodiniaceae symbioses are sensitive to climate change-induced ocean warming, which causes the disruption of symbiosis, commonly referred to as bleaching, and can lead to coral mortality. Cellular and molecular aspects of how this symbiosis is established and disrupted by heat stress are not well understood. The research presented herein characterizes immunity transcription factor NF-kappaB in the cnidarian model organism Exaiptasia pallida (Aiptasia). It is shown that the DNA-binding site specificity of Aiptasia NF-kappaB is similar to mammalian NF-kappaB subunit p50 and that this binding specificity is conserved across a broad expanse of metazoans. Moreover, Aiptasia and human IkappaB kinases can phosphorylate serine residues in the C-terminus of NF-kappaB, signaling the protein for proteasomal processing to allow for nuclear localization, DNA binding, and transactivation. In Aiptasia, NF-kappaB expression is downregulated by symbiosis onset in larvae, and NF-kappaB total expression, DNA-binding activity, and tissue-specific expression are increased following laboratory-induced loss of symbiosis in adult Aiptasia. NF-kappaB downregulation during the onset of symbiosis occurs only with the compatible symbiont Breviolum minutum and data suggest that host TGFbeta plays a role in NF-kappaB downregulation. Results demonstrate that aposymbiotic Aiptasia (with high NF-kappaB levels) have increased survival following bacterial infection as compared to symbiotic anemones. A bioinformatic analysis shows that potential NF-kappaB binding sites are enriched in promoter regions of immune-related genes that are upregulated in aposymbiotic Aiptasia. Increased levels of NF-kappaB are also found in a genet of the coral Pocillopora damicornis that exhibits resilience to heat-induced bleaching. Overall, the results in this thesis suggest a role for NF-kappaB-directed immunity in symbiosis onset, bleaching, and resistance to biological stressors in cnidarians. It is proposed that NF-kappaB downregulation in Aiptasia is a mechanism to lower host immunity and promote the establishment of symbiosis, but that this process compromises host immunity to pathogen infection. Nevertheless, constitutively high basal levels of NF-kappaB may be protective against bleaching in cnidarians.en_US
dc.language.isoen_US
dc.subjectBiologyen_US
dc.subjectAiptasiaen_US
dc.subjectBleachingen_US
dc.subjectCoralen_US
dc.subjectNF-κBen_US
dc.subjectPocillopora damicornisen_US
dc.subjectSymbiosisen_US
dc.titleCharacterization of immunity transcription factor NF-kappaB in a symbiotic Cnidarian model organism, the sea anemone Exaiptasia pallidaen_US
dc.typeThesis/Dissertationen_US
dc.date.updated2019-11-13T20:01:26Z
etd.degree.nameDoctor of Philosophyen_US
etd.degree.leveldoctoralen_US
etd.degree.disciplineBiologyen_US
etd.degree.grantorBoston Universityen_US


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