BEGIN:VCALENDAR VERSION:2.0 PRODID:icalendar-ruby CALSCALE:GREGORIAN METHOD:PUBLISH BEGIN:VTIMEZONE TZID:Europe/Vienna BEGIN:DAYLIGHT DTSTART:20230326T030000 TZOFFSETFROM:+0100 TZOFFSETTO:+0200 RRULE:FREQ=YEARLY;BYDAY=-1SU;BYMONTH=3 TZNAME:CEST END:DAYLIGHT BEGIN:STANDARD DTSTART:20231029T020000 TZOFFSETFROM:+0200 TZOFFSETTO:+0100 RRULE:FREQ=YEARLY;BYDAY=-1SU;BYMONTH=10 TZNAME:CET END:STANDARD END:VTIMEZONE BEGIN:VEVENT DTSTAMP:20260424T143154Z UID:6267c1da514a2339340145@ist.ac.at DTSTART:20230502T160000 DTEND:20230502T170000 DESCRIPTION:Speaker: David Vijatovic and Verena Hübschmann\nAbstract: Dav id Vijatovic (PhD student\, Sweeney group)Title and abstract:Dissecting sw im-to-walk transition and its neural basis during Xenopus frog metamorphos isTo parse the neural basis of motor behavior\, we capitalize on the uniqu e swim-to-walk transition of the Xenopus frog metamorphosis. This transiti on enables us to dissect the spinal circuitry for tail versus limb-based m ovement. We combine a robust behavioral assay with molecular cell-type pro filing in wild-type\, and then loss-of-function mutant\, tadpoles to evalu ate how neuronal diversity scales with and contributes to the increase in movement complexity over this transition.To characterize movement complexi ty\, we devised a high-speed behavioral set-up that tracks individual body parts of the frog. Using the SLEAP software\, we quantified intra- and in ter-body part movement and created locomotor profiles that we correlated w ith the cell-type composition of the spinal circuit.To assess spinal cell types at swim and limb stages\, we profiled the expression of transcriptio n factors that define motor neurons (MNs) and V1 interneurons (V1s)\, an i nhibitory class modulating MN firing. At free-swimming tadpole stages\, MN s and V1s double in number and diversify in their transcriptional profile\ , acquiring subpopulations resembling the mouse hypaxial and preganglionic motor columns and V1 clades. At metamorphosis\, spinal neuron diversity t hen peaks with the formation of limb motor columns and an increase in V1 n umber and diversity that largely matches the neonate mouse.We then asked h ow loss of cell-type diversity would alter the frogs motor repertoire. Usi ng CRISPR/Cas9\, we selectively knocked out three candidate master regulat or genes: FoxP1\, Hoxc9\, and Engrailed-1. By comparing the behavior of mu tant versus wild-type animals\, we unravel each cell subtypes contribution to tail and limb motor function.Our work maps MN and V1 molecular propert ies onto the tail and limb-based behavior of frog metamorphosis\, defining how transcriptional diversity scales with movement complexity. We also de monstrate the conservation of MN and V1 molecular organization between the frog\, the most ancient tetrapod\, and mouse\, a four-limbed mammal.Veren a Hbschmann (PhD student\, Siegert Group)Title and abstract:Human microgli a contribute to viral-mediated inflammation and impact neuronal activity i n retinal organoidsViral infection-induced inflammation during pregnancy h as been associated to malformation of the fetal brain and to long-term beh avioral consequences in adulthood such as schizophrenia. Microglia respond to inflammatory signals and at the same time are actively involved in neu ronal development. Yet\, little is known about how an inflammatory environ ment affects microglia during human embryonic development and which conseq uences this has on neuronal circuit formation and function. Human induced pluripotent stem cells (hiPSC) provide a unique opportunity to generate br ain region-specific models and to study their neuronal organization and co nnectivity.Recently\, we have shown that we can differentiate hiPSC into f unctional microglia-like cells (iMG) and retinal organoids (RO) 1\,2. Usin g both models allows us to overcome the limitation that organoids commonly lack microglia and to generate microglia-assembled retinal organoids (iMG -RO).Here\, we show that iMG successfully integrate into RO and colonize s ynaptic layers. However\, iMG presence has no immediate impact on the neur onal activity at baseline condition as determined with calcium imaging. To simulate a viral-mediated inflammatory environment\, we add poly(I:C) to iMG-RO. As anticipated\, iMG become activated leading to an inflammatory s ignature. Interestingly\, it also alters the calcium amplitude but not the frequency within neurons. To identify whether we can rescue the poly(I:C) -mediated effects\, we apply the anti-inflammatory drug Ibuprofen\, which can be taken during the first half of pregnancy. This treatment dampens iM G activation and mitigates inflammatory gene upregulation in RO. Remarkabl y\, only in the presence of iMG in RO\, Ibuprofen treatment rescues the in creased calcium amplitude suggesting that microglia are critical involved in resolving this effect. This provides first insights into how inflammati on during pregnancy might lead to neurological phenotypes in human.Bartals ka\, K.\, Hbschmann\, V.\, Korkut-Demirba\, M.\, Cubero\, R.J.A.\, Venturi no\, A.\, Rssler\, K.\, Czech\, T.\, and Siegert\, S. (2022). A systematic characterization of microglia-like cell occurrence during retinal organoi d differentiation. IScience 25\, 104580.Hbschmann\, V.\, Korkut-Demirba\, M\, and Siegert\, S. (2022). Assessing human iPSC-derived microglia identi ty and function by immunostaining\, phagocytosis\, calcium activity\, and inflammation assay. StarProtocol 3\, 4\, 101866. LOCATION: Heinzel Seminar Room\, Ground Floor\, Office Bldg West \, ISTA ORGANIZER:mmosiash@ist.ac.at SUMMARY:David Vijatovic and Verena Hübschmann: David Vijatovic and Veren a Hübschmann (NDT) URL:https://talks-calendar.ista.ac.at/events/4140 END:VEVENT END:VCALENDAR