BME PhD Defense Announcement for Matthew J. Thompson (D. Umulis and V. Munnamalai, Co-Chairs) Everyone is invited to attend the public presentation beginning at 11:30am EST. Title: Precision of Positional Information Along the Developing Cochlea Radial Axis: Linear BMP Activity Helps Set the Stage Date: September 14, 2022 Time: 11:30am EST Location: MJIS 2001 and Zoom* Committee: David M. Umulis, Co-Chair; Vidhya Munnamalai, Co-Chair; Srividya Iyer-Biswas; Michael G. Heinz; Tamara L. Kinzer-Ursem Abstract: Positional information encoded in signaling molecules is essential for early patterning in the prosensory domain of the developing cochlea. The cochlea contains an exquisite repeating pattern of sensory hair cells and supporting cells, and this requires precision in the morphogen signals that set the initial radial compartment boundaries, but this has not been investigated. To measure gradient formation and morphogenetic precision in developing cochlea, we developed a quantitative image analysis procedure measuring SOX2 and pSMAD1/5/9 profiles in mouse embryos at E12.5, E13.5, and E14.5. Intriguingly, we found that pSMAD1/5/9 profile forms a linear gradient in the medial ~75% of the PSD during embryonic day (E)12.5 and E13.5. This is a surprising readout of activity for a diffusive BMP4 ligand secreted from a tightly constrained lateral region, since morphogens typically form exponential or power-law gradient shapes. This is meaningful for gradient interpretation because while linear profiles offer the theoretically highest information content and distributed precision for patterning, a linear morphogen gradient has not yet been observed. In addition to the information-optimized linear profile, we found that while pSMAD1/5/9 is stable during this timeframe an accompanying gradient of SOX2 shifts dynamically. Third, we see through joint decoding maps of pSMAD1/5/9 and SOX2 that there is a high-fidelity mapping between signaling activity and position in the regions soon to become Kölliker's organ and the organ of Corti where radial patterns are more intricate. Mapping is ambiguous in the prosensory domain precursory to the outer sulcus, where cell fates are uniform. Altogether, this research provides new insights into the precision of early morphogenetic patterning cues in the radial cochlea prosensory domain. *Matthew Thompson is inviting you to a scheduled Zoom meeting. Topic: Matthew Thompson's PhD Defense Time: Sep 14, 2022 11:15 AM Eastern Time (US and Canada) Join Zoom Meeting https://purdue-edu.zoom.us/j/94518363803?pwd=QjQvd0x6ank0NjViODI3WW50UGRPUT0... Meeting ID: 945 1836 3803 Passcode: 722960 One tap mobile +13126266799,,94518363803#,,,,*722960# US (Chicago) +16465588656,,94518363803#,,,,*722960# US (New York) Dial by your location +1 312 626 6799 US (Chicago) +1 646 558 8656 US (New York) +1 646 931 3860 US +1 301 715 8592 US (Washington DC) +1 309 205 3325 US +1 669 444 9171 US +1 669 900 6833 US (San Jose) +1 719 359 4580 US +1 253 215 8782 US (Tacoma) +1 346 248 7799 US (Houston) +1 386 347 5053 US +1 564 217 2000 US Meeting ID: 945 1836 3803 Passcode: 722960 Find your local number: https://purdue-edu.zoom.us/u/abPZ15oKzK