{"600181":{"#nid":"600181","#data":{"type":"event","title":"Geochemical Controls on Protocell Self-Assembly in the Origins of Life","body":[{"value":"\u003Ch4\u003EEAS Spring 2018 Seminar Series Presents: Dr. Nita Sahai, University of Akron\u003C\/h4\u003E\r\n\r\n\u003Cp\u003EThe focus of our work is to determine the constraints placed by atmosphere-water-rock interactions on the environmental conditions for self-assembly of the molecular building blocks of the earliest like-like entities, \u0026ldquo;protocells.\u0026rdquo;\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003EWe have addressed the problem that modern\u003Cstrong\u003E \u003C\/strong\u003Egeochemical concentrations of total dissolved phosphate (\u003Cstrong\u003EP\u003Csub\u003ET\u003C\/sub\u003E\u003C\/strong\u003E) and Mg\u003Csup\u003E2+\u003C\/sup\u003E are much lower than those are required for non-enzyamtic (prebiotic) RNA synthesis, while Mg\u003Csup\u003E2 \u003C\/sup\u003Eand Ca\u003Csup\u003E2+\u003C\/sup\u003E concentrations are too high for membrane stability, so how did life emerge on early Earth?\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003EWe used a geochemical thermodynamic modeling approach, to show that a single, globally-occurring geological process of komatiite rock weathering and evaporation of the resulting solutions under specific partial pressures of atmospheric CO\u003Csub\u003E2\u003C\/sub\u003E (P\u003Csub\u003ECO2\u003C\/sub\u003E) can quantitatively provide the P\u003Csub\u003ET\u003C\/sub\u003E, Mg\u003Csup\u003E2+\u003C\/sup\u003E and Ca\u003Csup\u003E2+\u003C\/sup\u003E concentrations required for nucleotide synthesis, RNA polymerization and protocell-membrane stability.\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003EConversely, the biologically-required concentrations of P\u003Csub\u003ET\u003C\/sub\u003E, Mg\u003Csup\u003E2+\u003C\/sup\u003E and Ca\u003Csup\u003E2+\u003C\/sup\u003E place constraints on the P\u003Csub\u003ECO2\u003C\/sub\u003E levels on early Earth compared to previous estimates ranging over five orders of magnitude. Using these environmental constraints on Mg\u003Csup\u003E2+\u003C\/sup\u003E and Ca\u003Csup\u003E2+\u003C\/sup\u003E concentrations, we examined the stability and evolution of simple protocell membranes from pure single chain amphiphile (SCA) compositions through mixed SCA-phospholipid (PL) to pure PL compositions found in modern cells.\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003EWe showed that, rather than acting being toxic, the divalent cations promoted evolution of the membranes towards more modern compositions. We also found that RNA oligomer synthesis is possible even at much lower concentrations of Mg\u003Csup\u003E2+\u003C\/sup\u003E than previously reported, well within the concentration range constrained by the atmosphere-water-rock interactions.\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003EThus, we have used a geochemical modeling approach to create the components of a simple protocell under geochemically plausible conditions.\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":"A seminar by Dr. Nita Sahai, School of Earth and Atmospheric Sciences Spring 2018 Seminar Speaker Series"}],"uid":"34458","created_gmt":"2017-12-21 14:34:52","changed_gmt":"2018-01-31 17:00:07","author":"nlawson3","boilerplate_text":"","field_publication":"","field_article_url":"","field_event_time":{"event_time_start":"2018-03-01T11:00:00-05:00","event_time_end":"2018-03-01T11:50:00-05:00","event_time_end_last":"2018-03-01T11:50:00-05:00","gmt_time_start":"2018-03-01 16:00:00","gmt_time_end":"2018-03-01 16:50:00","gmt_time_end_last":"2018-03-01 16:50:00","rrule":null,"timezone":"America\/New_York"},"extras":[],"hg_media":{"600172":{"id":"600172","type":"image","title":"Nita Sahai","body":null,"created":"1513863576","gmt_created":"2017-12-21 13:39:36","changed":"1513863576","gmt_changed":"2017-12-21 13:39:36","alt":"","file":{"fid":"228805","name":"Nita Sahai.jpg","image_path":"\/sites\/default\/files\/images\/Nita%20Sahai.jpg","image_full_path":"http:\/\/hg.gatech.edu\/\/sites\/default\/files\/images\/Nita%20Sahai.jpg","mime":"image\/jpeg","size":71258,"path_740":"http:\/\/hg.gatech.edu\/sites\/default\/files\/styles\/740xx_scale\/public\/images\/Nita%20Sahai.jpg?itok=gKFUOja-"}}},"media_ids":["600172"],"groups":[{"id":"364801","name":"School of Earth and Atmospheric Sciences (EAS)"}],"categories":[],"keywords":[{"id":"175623","name":"EAS Seminar"}],"core_research_areas":[],"news_room_topics":[],"event_categories":[{"id":"1795","name":"Seminar\/Lecture\/Colloquium"}],"invited_audience":[{"id":"78761","name":"Faculty\/Staff"},{"id":"174045","name":"Graduate students"},{"id":"78751","name":"Undergraduate students"}],"affiliations":[],"classification":[],"areas_of_expertise":[],"news_and_recent_appearances":[],"phone":[],"contact":[{"value":"\u003Cp\u003EHost: Jennifer Glass\u003C\/p\u003E\r\n\r\n\u003Cp\u003ELogistics: Natasha Lawson\u003C\/p\u003E\r\n","format":"limited_html"}],"email":[],"slides":[],"orientation":[],"userdata":""}}}