{"648727":{"#nid":"648727","#data":{"type":"event","title":"PhD Defense by Emily Brown","body":[{"value":"\u003Cp\u003EIn partial fulfillment of the requirements for the degree of\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003EDoctor of Philosophy in Biology\u003C\/p\u003E\r\n\r\n\u003Cp\u003EIn the\u003C\/p\u003E\r\n\r\n\u003Cp\u003ESchool of Biological Sciences\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cstrong\u003EEmily Brown\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003EWill defend her dissertation\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003ECellular mechanisms of ecological interactions\u003C\/p\u003E\r\n\r\n\u003Cp\u003Eamong marine phytoplankton\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003EThursday, July 22\u003Csup\u003End\u003C\/sup\u003E, 2021\u003C\/p\u003E\r\n\r\n\u003Cp\u003E1:00 PM\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Ca href=\u0022https:\/\/bluejeans.com\/475557684\/3861\u0022\u003Ehttps:\/\/bluejeans.com\/475557684\/3861\u003C\/a\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003EMeeting ID: 475 576 684\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003Cstrong\u003EThesis Advisor:\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003EJulia Kubanek, Ph.D.\u003C\/p\u003E\r\n\r\n\u003Cp\u003ESchool of Biological Sciences\u003C\/p\u003E\r\n\r\n\u003Cp\u003ESchool of Chemistry and Biochemistry\u003C\/p\u003E\r\n\r\n\u003Cp\u003EGeorgia Institute of Technology\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cstrong\u003ECommittee Members:\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003EMark Hay, Ph.D.\u003C\/p\u003E\r\n\r\n\u003Cp\u003ESchool of Biological Sciences\u003C\/p\u003E\r\n\r\n\u003Cp\u003EGeorgia Institute of Technology\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003EJoseph Montoya, Ph.D.\u003C\/p\u003E\r\n\r\n\u003Cp\u003ESchool of Biological Sciences\u003C\/p\u003E\r\n\r\n\u003Cp\u003EGeorgia Institute of Technology\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003EPamela Peralta-Yahya, Ph.D.\u003C\/p\u003E\r\n\r\n\u003Cp\u003ESchool of Chemistry and Biochemistry\u003C\/p\u003E\r\n\r\n\u003Cp\u003ESchool of Chemical and Biomolecular Engineering\u003C\/p\u003E\r\n\r\n\u003Cp\u003EGeorgia Institute of Technology\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003EVinayak Agarwal, Ph.D.\u003C\/p\u003E\r\n\r\n\u003Cp\u003ESchool of Chemistry and Biochemistry\u003C\/p\u003E\r\n\r\n\u003Cp\u003ESchool of Biological Sciences\u003C\/p\u003E\r\n\r\n\u003Cp\u003EGeorgia Institute of Technology\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003EABSTRACT: The current body of work investigates the chemical mechanisms involved in predator-prey interactions using species from the chemically defended phytoplankton genus \u003Cem\u003EAlexandrium\u003C\/em\u003E and cues from one type of predatory zooplankton, copepods. To explore the role of dead phytoplankton cues in predation risk assessment and chemical defense plasticity, we exposed \u003Cem\u003EA. minutum\u003C\/em\u003E to chemical cues from six different lysed phytoplankton species. Chemical cues from dead conspecifics and congenerics drastically suppressed \u003Cem\u003EA.\u0026nbsp;minutum\u003C\/em\u003E toxin production, their chemical defense, and modestly enhanced growth regardless of their geographic co-occurrence. In contrast, exposure to cues from distantly related, but historically co-occurring phytoplankton species induced toxin production and decreased growth in \u003Cem\u003EA.\u0026nbsp;minutum\u003C\/em\u003E by roughly the same magnitude. This study revealed that \u003Cem\u003EA. minutum\u003C\/em\u003E perceives cues from dead competitors and that phylogenetic relatedness of the competitor is important in how it trades-off utilization of resources for either growth or defense. We also investigated how \u003Cem\u003EA.\u0026nbsp;minutum\u003C\/em\u003E perceives copepodamides, a suite of copepod metabolites known to induce resistance against predators in diverse phytoplankton taxa, and what metabolic pathways are involved in initiating of \u003Cem\u003EA. minutum\u003C\/em\u003E\u0026rsquo;s chemical defense. Recognition of copepodamides caused subtle, targeted changes in the metabolome of \u003Cem\u003EA.\u0026nbsp;minutum\u003C\/em\u003E including dysregulation of valine biosynthesis and enhancement of butanoate metabolism and arginine biosynthesis, as determined by nuclear magnetic resonance (NMR) and mass spectrometry (MS) based metabolomics. Additionally, inhibition experiments led to the discovery that copepodamides trigger signal transduction via disruption of serine\/threonine phosphatases, which leads to increased jasmonic acid biosynthesis and signaling, and ultimately results in amplified toxin biosynthesis in \u003Cem\u003EA.\u0026nbsp;minutum\u003C\/em\u003E. In addition to understanding how phytoplankton recognize and respond to predators, it is also valuable to understand how predators, such as copepods, select prey. We proposed that when selecting prey copepods may detect chemical cues on phytoplankton cell surfaces that are associated with toxicity rather than directly sensing the intracellular toxins. Using MS and NMR-based metabolomics, we discovered that the non-polar metabolomes of two \u003Cem\u003EAlexandrium\u003C\/em\u003E toxic species vary considerably from their non-toxic congener even though all three are very closely related. Metabolites belonging to seven different lipid classes were implicated in distinguishing the non-polar metabolomes of the \u003Cem\u003EAlexandrium\u003C\/em\u003E species based on toxicity. Ultimately, we partially identified three metabolites which exhibited the greatest enrichment in both toxic species relative to the non-toxic species. Overall, my dissertation research provides insight into mechanisms that mediate ecological interactions involving marine phytoplankton. These include assessment of predation risk, physiological mechanisms behind predator cue recognition and response, and cellular traits that may enable predators to distinguish toxic from non-toxic cells, leading to increased fitness for chemically defended prey. This thesis further demonstrates the complexity of planktonic interactions at both organismal and molecular levels.\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n","summary":null,"format":"limited_html"}],"field_subtitle":"","field_summary":"","field_summary_sentence":[{"value":"CELLULAR MECHANISMS OF ECOLOGICAL INTERACTIONS  AMONG MARINE PHYTOPLANKTON"}],"uid":"27707","created_gmt":"2021-07-13 17:16:01","changed_gmt":"2021-07-13 17:16:01","author":"Tatianna Richardson","boilerplate_text":"","field_publication":"","field_article_url":"","field_event_time":{"event_time_start":"2021-07-22T14:00:00-04:00","event_time_end":"2021-07-22T17:00:00-04:00","event_time_end_last":"2021-07-22T17:00:00-04:00","gmt_time_start":"2021-07-22 18:00:00","gmt_time_end":"2021-07-22 21:00:00","gmt_time_end_last":"2021-07-22 21:00:00","rrule":null,"timezone":"America\/New_York"},"extras":[],"groups":[{"id":"221981","name":"Graduate Studies"}],"categories":[],"keywords":[{"id":"100811","name":"Phd Defense"}],"core_research_areas":[],"news_room_topics":[],"event_categories":[{"id":"1788","name":"Other\/Miscellaneous"}],"invited_audience":[{"id":"78761","name":"Faculty\/Staff"},{"id":"78771","name":"Public"},{"id":"78751","name":"Undergraduate students"}],"affiliations":[],"classification":[],"areas_of_expertise":[],"news_and_recent_appearances":[],"phone":[],"contact":[],"email":[],"slides":[],"orientation":[],"userdata":""}}}