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SUMMARY:Meng Zhu-Maternal oxygen levels regulate the timing of limb develo
 pment in amniote species\; Alex Plum-Morphogen patterning in dynamic tissu
 es - Meng Zhu\; Alex Plum
DTSTART:20251124T143000Z
DTEND:20251124T153000Z
UID:TALK236425@talks.cam.ac.uk
CONTACT:Jia CHEN
DESCRIPTION:Name: Meng Zhu Affiliation: Tabin lab\, Harvard University\n\n
 Title: Maternal oxygen levels regulate the timing of limb development in a
 mniote species\n\nAbstract:\n\nHeterochrony\, or the alternation of develo
 pmental timing\, is an important mechanism underlying changes during evolu
 tion. A notable example involves the timing of amniote limb formation\, wh
 ere avian species display synchronized growth of the forelimbs and hindlim
 bs\, while mammalian species show a marked delay in hindlimb development r
 elative to forelimb. This is hypothesized to have evolved in the context o
 f an energy trade-off involving constrained nutrient supplies in the early
  development of eutherian mammals\, yet the molecular basis of the delay i
 s poorly understood. We here show that mammalian limb heterochrony is evid
 ent from the time the limb buds are first initiated\, and is associated wi
 th heterochronic expression of T-box transcription factors. This heterochr
 onic change relative to non-mammalian embryos is not due to changes in cis
 -regulatory elements controlling T-box gene suppression\, but unexpectedly
 \, is regulated by the differential oxygen levels to which avian and mamma
 lian embryos are exposed at prelimb initiation stages. By integrating RNA-
 sequencing analyses with genetic assays\, we found that hypoxia's impact o
 n hindlimb development is at least partially mediated through the expressi
 on of NFKB transcription factor\, cRel. Taken together\, these results pro
 vide mechanistic understanding of an important example of developmental he
 terochrony and exemplify the importance of the maternal environment in reg
 ulating the timing of embryonic development. In addition\, our results hel
 p to explain the limb-type specific venerability to gestational hypoxia.\n
 \nName: Alex Plum Affiliation: University of California San Diego (Biophys
 ics PhD student)\n\nTitle: Morphogen patterning in dynamic tissues\n\nAbst
 ract:\n\nEmbryogenesis integrates morphogenesis—coordinated cell movemen
 ts—with cell differentiation\, often informed by morphogen patterning. W
 hile largely studied independently\, morphogenesis and patterning often un
 fold simultaneously in early embryos. Yet how cell movements affect morpho
 gen transport and cells' exposure over time remains unclear\, as most patt
 ern formation models assume static tissues. Here we develop a theoretical 
 framework for morphogen patterning in dynamic tissues\,\n\nrecasting advec
 tion-reaction-diffusion equations in the cells' moving reference frames. T
 his framework (i) elucidates how morphogenesis mediates morphogen transpor
 t and compartmentalization: cell-cell diffusive transport is enhanced at m
 ulticellular flow attractors\, while repellers act as barriers\, affecting
  cell fate induction and bifurcations. (ii) It formalizes cell-cell signal
 ing ranges in dynamic tissues\, deconfounding morphogenetic movements to i
 dentify which cells could communicate via morphogens. (iii) It provides tw
 o new nondimensional numbers to assess when and where morphogenesis affect
 s morphogen transport. We demonstrate this framework by analyzing classica
 l patterning models with common morphogenetic motifs as well as experiment
 al tissue flows. Our work rationalizes dynamic tissue patterning in develo
 pment\, constraining candidate patterning mechanisms and parameters using 
 accessible cell motion data.
LOCATION:Online
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