Identification of novel secreted compounds from the amphibian pathogen Batrachochytrium dendrobatidis

dc.contributor.committeeChairSan Francisco, Michael
dc.contributor.committeeMemberSan Francisco, Susan
dc.contributor.committeeMemberZak, John
dc.contributor.committeeMemberHamood, Abdul
dc.contributor.committeeMemberRollins-Smith, Louise
dc.creatorStarr, Amanda M.
dc.creator.orcid0000-0002-1705-7164
dc.date.accessioned2020-07-08T15:50:30Z
dc.date.available2020-07-08T15:50:30Z
dc.date.created2019-08
dc.date.issued2019-08
dc.date.submittedAugust 2019
dc.date.updated2020-07-08T15:50:30Z
dc.description.abstractGlobal amphibian decline is caused in large measure by the fungal pathogen, Batrachochytrium dendrobatidis. The fungus produces a motile zoospore that is attracted to the keratin rich layer of epidermal skin, where it produces a suite of proteases to help degrade intercellular junctions, elastin, and antimicrobial peptides. The zoospore resorbs its flagellum, produces a germ tube to infiltrate deeper into epidermal layers, and transitions into a thallus. The thallus then differentiates into a zoosporangium and produces secreted metabolites that alter the immunological response of the amphibian. Infected animals have thickened skin which is sloughed off. Because the skin of amphibians plays a major role in air and moisture exchange, the resulting osmotic imbalance is believed to lead to eventual death of infected animals by cardiac arrest. An unexplained symptom of the B. dendrobatidis infection on amphibians is the loss of their righting reflex. Previous research has suggested that B. dendrobatidis possesses a non-ribosomal peptide synthetase (NRPS). This dissertation research has shown that B. dendrobatidis possesses NRPS-encoding genes. We hypothesized that B. dendrobatidis produces secondary metabolites that may play a role in its pathogenicity. Growth of the fungus in rich media supplemented with lactose and heat-killed bacteria was most effective for induction of the NRPS gene cluster and other genes responsible for the synthesis of secondary metabolites. Cell culture filtrates of B. dendrobatidis grown in various modified media were subjected to high performance liquid chromatography-mass spectrometry and data analyzed by Compound Discoverer 3.0. Among the products observed, three were identified that have not been previously reported to be produced by this pathogen. The use of wax moth larvae (Galleria mellonella), as a whole organism bioassay system, to study pathogenicity of B. dendrobatidis in this work, establishes it as a novel entity for investigation as we preserve our precious resource of amphibians.
dc.format.mimetypeapplication/pdf
dc.identifier.urihttps://hdl.handle.net/2346/86131
dc.language.isoeng
dc.rights.availabilityRestricted from online display. To be vetted for access, please click on Request a Copy on the left or contact the author directly.
dc.subjectChytrid
dc.subjectVirulence
dc.titleIdentification of novel secreted compounds from the amphibian pathogen Batrachochytrium dendrobatidis
dc.typeThesis
dc.type.materialtext
thesis.degree.departmentBiological Sciences
thesis.degree.disciplineBiology
thesis.degree.grantorTexas Tech University
thesis.degree.levelDoctoral
thesis.degree.nameDoctor of Philosophy

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