{ "136577-21878875": { "datetime_modified":"20260325T152032", "datetime_start":"20260417T120000", "datetime_end":"20260417T130000", "has_end_time":1, "date_start":"2026-04-17", "date_end":"2026-04-17", "time_start":"12:00:00", "time_end":"13:00:00", "time_zone":"America\/Detroit", "event_title":"Two extremes of liquid-liquid phase separation in membranes: minimal, artificial membranes with only two lipids vs. living, biological membranes with hundreds of components", "occurrence_title":"", "combined_title":"Two extremes of liquid-liquid phase separation in membranes: minimal, artificial membranes with only two lipids vs. living, biological membranes with hundreds of components: Sarah Keller (University of Washington)", "event_subtitle":"Sarah Keller (University of Washington)", "event_type":"Workshop \/ Seminar", "event_type_id":"21", "description":"Amidst longstanding excitement about liquid\u2013liquid phase separation in biological contexts, fundamental questions have persisted about exactly which molecules are required for this transition in lipid membranes. The Keller Group applies those questions to both artificial and biological membranes. In simple membranes, enormous progress has been made in understanding large-scale, liquid-liquid phase separation in membranes with as few as three components: a sterol, lipid with ordered chains, and a lipid with disordered chains. How low can we go? Are three components really necessary? Our group set out to discover a truly minimal system with only two components. Inspired by reports that sterols interact closely with lipids with ordered chains, we found that phase separation can robustly occur in bilayers in which a sterol and lipid are replaced by a single, joined sterol\u2013lipid. Next, we turned our attention to natural membranes. Micron-scale liquid-liquid phase separation occurs in vacuole membranes of budding yeast (S. cerevisiae) at their growth temperature when the yeast switch from the log stage of growth to the stationary stage. The membrane phases are functionally important \u2013 they play a role in enabling the yeast to survive periods of stress. We found that yeast actively regulate this phase transition to hold the membrane transition of their membrane ~15C above the yeast growth temperature. They must do so by changing their lipidome. When yeast enter the stationary stage (and their membranes phase separate), the fraction of one lipid type (PC-lipids) doubles, and lipids of that type have higher melting temperatures, which is consistent with phase separation occurring in membranes containing a sterol, lipids with ordered chains, and lipids with disordered chains.", "occurrence_notes":null, "guid":"136577-21878875@events.umich.edu", "permalink":"http:\/\/events.umich.edu\/event\/136577", "building_id":"1000158", "building_name":"Chemistry Dow Lab", "campus_maps_id":"34", "room":"1640", "location_name":"Chemistry Dow Lab", "has_livestream":0, "cost":"", "tags":["Biophysics"], "website":"https:\/\/chem.washington.edu\/people\/sarah-l-keller", "sponsors":[ { "group_name":"LSA Biophysics", "group_id":"3767", "website":"" } ], "image_url":"", "styled_images":{ "event_thumb":"", "event_large":"", "event_large_2x":"", "event_large_lightbox":"", "group_thumb":"", "group_thumb_square":"", "group_large":"", "group_large_lightbox":"", "event_large_crop":"", "event_list":"", "event_list_2x":"", "event_grid":"", "event_grid_2x":"", "event_feature_large":"", "event_feature_thumb":"" }, "occurrence_count":1, "first_occurrence":21878875 } , "147781-21901964": { "datetime_modified":"20260415T164254", "datetime_start":"20260420T130000", "datetime_end":"20260420T140000", "has_end_time":1, "date_start":"2026-04-20", "date_end":"2026-04-20", "time_start":"13:00:00", "time_end":"14:00:00", "time_zone":"America\/Detroit", "event_title":"CHPS Seminar | Reconstructing the properties of the protosolar disk using cosmochemistry", "occurrence_title":"", "combined_title":"CHPS Seminar | Reconstructing the properties of the protosolar disk using cosmochemistry: Alessandro Morbidelli (Observatoire de la Cote d'Azur)", "event_subtitle":"Alessandro Morbidelli (Observatoire de la Cote d'Azur)", "event_type":"Workshop \/ Seminar", "event_type_id":"21", "description":"Observations of protoplanetary disks with ALMA have revealed a large diversity of properties, but also some common tendencies in terms of dust\/gas density and radial extension ratios, as well as the appearance of features like rings and gaps or cavities. It is too late to observe the proto-solar disk, but many of its properties can be inferred from the current distribution of planetesimals and using cosmochemical constraints on the chronology of planetesimal accretion and the isotopic heterogeneity of the disk. I will review the available data, which can be used to reconstruct the proto-solar disk. The view that emerges is that of a quite standard disk of about 90 au in gas radius and 45 au in dust radius, forming planetesimals at two distinct epochs (one of which is very early, while the disk was presumably still in Class-0 or Class-1 stage) and evolving towards a transition disk at the appearance of Jupiter and Saturn. Similarities and differences with the PDS70 disk will be discussed.", "occurrence_notes":null, "guid":"147781-21901964@events.umich.edu", "permalink":"http:\/\/events.umich.edu\/event\/147781", "building_id":"1000167", "building_name":"West Hall", "campus_maps_id":"163", "room":"411", "location_name":"West Hall", "has_livestream":0, "cost":"", "tags":["Astronomy","Free","Physics","Talk"], "website":"https:\/\/lsa.umich.edu\/physics", "sponsors":[ { "group_name":"LSA Biophysics", "group_id":"3767", "website":"" } ], "image_url":"", "styled_images":{ "event_thumb":"", "event_large":"", "event_large_2x":"", "event_large_lightbox":"", "group_thumb":"", "group_thumb_square":"", "group_large":"", "group_large_lightbox":"", "event_large_crop":"", "event_list":"", "event_list_2x":"", "event_grid":"", "event_grid_2x":"", "event_feature_large":"", "event_feature_thumb":"" }, "occurrence_count":1, "first_occurrence":21901964 } }