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Tue 24 Jun 14:00: The statistical challenges in tackling persistent climate model uncertainty through model-observation comparisons. https://teams.microsoft.com/l/meetup-join/19%3ameeting_OWJjY2ViNjktOWZjMS00NGJmLWI5MTUtNTYxM2E5MTgyMTQ1%40thread.v2/0...
Abstract: The effects of aerosols on the Earth’s energy balance since pre-industrial times (aerosol radiative forcing) has significantly and repeatedly dominated the uncertainty in reported estimates of global temperature change from the IPCC . The magnitude of aerosol radiative forcing of climate over the industrial period is estimated to lie between about -2 and -0.4 W m-2, compared to a much better understood forcing of 1.6 to 2.0 W m-2 due to CO2 . In this seminar, past efforts to quantify the range of possible aerosol forcings predicted from an aerosol-climate model that are caused by parametric uncertainty, and to constrain that forcing uncertainty through model-observation comparison using extensive aerosol and cloud-based measurements from ships, flight campaigns, satellites and ground stations, will be discussed. We find that despite a very large reduction in plausible parameter space and reasonable constraint on observable properties, the observational constraint based on this comprehensive set of measurements only partially reduces the range of aerosol radiative forcings from our model. In the NERC project ‘Towards Maximum Feasible Reduction in Aerosol Forcing Uncertainty’ (Aerosol-MFR), several key statistical challenges highlighted from this work are being addressed in order to improve the model-observation comparison process for uncertainty constraint. This includes optimising the way observational constraints are applied, designing new approaches for reducing error compensation effects and using the PPE to identify and characterise model structural errors. Preliminary results from the project so far will be outlined, along with further plans to tackle this important problem.
Biography: Dr Jill Johnson is a Lecturer in Statistics in the School of Mathematical and Physical Sciences at the University of Sheffield. Her research interests are in the development and practical application of statistical methods to quantify, assess and then reduce uncertainty in large-scale complex models of real-world systems, with a focus on problems in environmental science. Prior to joining Sheffield in August 2021, Jill worked as an applied statistician / research associate for over 8 years in the aerosol research group at the Institute for Climate and Atmospheric Science, University of Leeds, where her work focussed on the quantification and constraint of key uncertainties in models of the atmosphere and climate. Her current research builds on this work, including the NERC research project ‘Towards Maximum Feasible Reduction in Aerosol Forcing Uncertainty (Aerosol-MFR)’.
https://teams.microsoft.com/l/meetup-join/19%3ameeting_OWJjY2ViNjktOWZjMS00NGJmLWI5MTUtNTYxM2E5MTgyMTQ1%40thread.v2/0?context=%7b%22Tid%22%3a%2249a50445-bdfa-4b79-ade3-547b4f3986e9%22%2c%22Oid%22%3a%228b208bd5-8570-491b-abae-83a85a1ca025%22%7d
- Speaker: Dr Jill S Johnson; School of Mathematical and Physical Sciences, University of Sheffield, UK
- Tuesday 24 June 2025, 14:00-15:00
- Venue: Chemistry Dept, Unilever Lecture Theatre and Teams.
- Series: Centre for Atmospheric Science seminars, Chemistry Dept.; organiser: Yao Ge.
Wed 04 Jun 14:00: The Australian Antarctic Program Partnership (AAPP) Biogeochemistry Project: Understanding the changing Southern Ocean carbon cycle
The Australian Antarctic Program Partnership (AAPP) is focused on understanding the nature and impacts of Southern Ocean Change. The Biogeochemistry Project, one of the seven complementary initiatives within the AAPP , combines observations, models and data syntheses to understand changes in the Southern Ocean carbon cycle. This work is undertaken in collaboration with other government agencies, national infrastructure programs, and academic institutions, and highlights the use of essential ocean observations and models to improve understanding and deliver impact. An overview of recent field programs will be presented, along with new work to quantify the uptake and storage of anthropogenic CO2 in the ocean, to validate estimates of ocean carbon export from autonomous platforms, and to improve model representation of air-sea CO2 exchange.
- Speaker: Elizabeth H. Shadwick, CSIRO Environment
- Wednesday 04 June 2025, 14:00-15:00
- Venue: BAS Seminar Room 1.
- Series: British Antarctic Survey - Polar Oceans seminar series; organiser: Dr Birgit Rogalla.
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Mon 19 May 14:30: For both titles please look in the abstract session below. Please sign in at the Gurdon reception upon entry and the seminar will take place in the tea room.
Katie Goodwin Title: Physical confinement in the developing mouse embryo puts migrating primordial germ cells at risk of DNA damage
Abstract: High fidelity passing on of genetic material is essential to reproduction. Typically, this is accomplished by primordial germ cells (PGCs), which eventually produce sperm or eggs. In most animals, PGCs are specified far from the future gonads and must migrate through developing tissues to reach them. Failure to complete this journey can result in infertility or extra-gonadal germ cell tumours. Despite this important biomedical relevance, very little is known about PGC migration in mammalian embryos. Here, we performed dynamic and in-depth analyses of PGC migration during mouse embryogenesis, encompassing historically inaccessible stages. We found that migrating PGCs extend dynamic actin-rich protrusions, indicative of a migration strategy distinct to that used in non-mammalian model organisms. Their protrusive migration enables them to navigate through ECM barriers and increasingly developed tissues. These morphogenetic changes around PGCs impose increasing physical confinement, leading to significant nuclear deformation and even cell rupture. Endogenous and artificial increases in confinement lead to an increased incidence of DNA damage in PGCs, but not somatic cells. As a possible adaptation to mitigate this surprising stress, we found that PGCs deplete their nuclear lamina and have highly wrinkled nuclear envelopes that may enable them to squeeze through confined spaces damage-free. Overall, our insights into the fascinating journey of PGCs during mouse embryogenesis raise important questions about DNA repair, nuclear adaptations, and genome integrity in the mammalian germline.
Miguel Ángel Ortiz Salazar Title: Endogenous Nodal diverts Wnt signaling interpretation from posterior mesoderm to definitive endoderm in geometrically constrained human pluripotent cells.
Abstract: The ligands FGF8 and WNT3A are crucial for embryonic development. They are involved in cell migration, aid mesoderm induction early at gastrulation, and fuel axial elongation by generating Neuromesodermal progenitors (NMPs) that pattern posterior cell fates in the embryo. While both events have been extensively studied, the mechanisms by which these signals produce different outcomes depending on the context remain elusive. Here, we studied how the Wnt signaling dynamics correlate with their cell fate.
When human embryonic stem cells are exposed to these signals under standard culture conditions, they indeed induce an NMP -like state. In contrast, however, when the same protocol is performed in geometrically constrained colonies, an intricate 3D structure emerges, featuring a ball of epiblast disk-like cells (SOX2+, OCT4 , NANOG , ECAD ) on top of layers of definitive endoderm (DE) (SOX17, FOXA2 , GATA6 , NCAD , OTX2 ). When these structures are exposed to increasing WNT doses, signaling levels as measured with live GFP ::ß-catenin are elevated. However, these elevated WNT signals do not induce mesoderm or posteriorize the responding cells, challenging the classic concentration-dependent morphogen mechanism. By manipulating signaling pathways, we found that DE differentiation results from elevated endogenous NODAL signaling together with the exogenous WNT stimulation. The ability of WNT to induce NMPs and their specialized descendants, pre-somitic mesoderm (PSM) or neural progenitors (CDX1+, CDX2 , and TBX6 or SOX1 , SOX2 ) is restored only when WNT activation is combined with NODAL inhibition. Furthermore, combining live NODAL dynamics with time-point inhibitions, revealed that allowing NODAL signaling for the first 24 hours, enhances PSM induction while allowing it for 48 hours induces both DE and PSM fates. This shows that NODAL changes how the WNT signal is interpreted and is the main determinant of whether cells differentiate to endoderm or mesoderm. Finally, we determined that CHIR , a commonly used chemical Wnt activator, can induce PSM in a concentration-dependent manner with qualitatively different signaling dynamics through both the WNT and NODAL pathways compared to stimulation with WNT3A ligand.
Collectively, we demonstrate that cell fate decision-making is determined by the interplay between multiple pathways and not only by the levels of a single pathway, highlighting the dynamic nature of development.
This work has been funded by the National Science Foundation (MCB-2135296), Rice University, and Consejo Nacional de Ciencia y Tecnología (CONACYT – 41944)
Please sign in at the Gurdon reception upon entry and the seminar will take place in the tea room.
- Speaker: Katie Goodwin-MRC LMB; Miguel Ángel Ortiz Salazar-MRC LMB
- Monday 19 May 2025, 14:30-15:30
- Venue: In person at Gurdon Institute and Online.
- Series: Morphogenesis Seminar Series; organiser: Jia CHEN.
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Mon 09 Jun 14:30: Ana Patricia Ramos-Forming an Eye: from cell behaviour to tissue shape changes;
Ana Patricia Ramos
Title:Forming an Eye: from cell behaviour to tissue shape changes
Abstract: Building an organ is a multistep process in which correct morphogenesis arises from feedback loops between genetic regulation and mechanical forces. A key morphogenetic event is the emergence of tissue curvature, which is essential for various developmental processes, such as gastrulation, and shapes multiple organs, including the heart and neural tube.
Curvature can develop alongside other cellular and tissue rearrangements. In many of these complex contexts, the biomechanical interactions driving curvature remain unclear, as the contributions of individual rearrangements and their interplay are difficult to disentangle.
To address this, we investigated the morphogenesis of the vertebrate optic cup, a highly curved structure that forms from a flat bilayered optic vesicle. Using zebrafish as a model system, where cell and tissue dynamics can be studied in native 4D conditions, we combined in vivo experiments, 4D segmentation and analysis, and theoretical modeling. This interdisciplinary approach allowed us to identify key players driving the emergence of optic cup curvature.
- Speaker: Kumud Saini, Robinson Lab, Sainsbury Laboratory & Ana Patricia Ramos, IGC, Portugal
- Monday 09 June 2025, 14:30-15:30
- Venue: Online.
- Series: Morphogenesis Seminar Series; organiser: Jia CHEN.
Mon 02 Jun 14:30: Maik Bischoff-Plexin/Semaphorin Antagonism Orchestrates Collective Cell Migration and Organ Sculpting by Regulating Epithelial-Mesenchymal Balance; Harry McNamara-Decoding and controlling self-organization in stem cell models of...
Maik Christian Bischoff
Title: Plexin/Semaphorin Antagonism Orchestrates Collective Cell Migration and Organ Sculpting by Regulating Epithelial-Mesenchymal Balance
Abstract:Cell behavior emerges from the intracellular distribution of properties like protrusion, contractility, and adhesion. Thus, characteristic emergent rules of collective migration can arise from cell-cell contacts locally tweaking architecture, orchestrating self-regulation during development, wound healing, and cancer progression. The Drosophila testis-nascent-myotube-system allows dissection of contact-dependent migration in vivo at high resolution. Here, we describe a role for the axon guidance factor Plexin A in collective cell migration: maintaining cell-cell interfaces at a precise point on the epithelial-mesenchymal spectrum. This is crucial for testis myotubes to migrate as a continuous sheet, allowing normal sculpting-morphogenesis. Cells must maintain filopodial N-cadherin-based junctions and remain ECM -tethered near cell-cell contacts to spread while collectively moving. Our data further suggest Semaphorin 1b is a Plexin A antagonist, fine-tuning activation. This reveals a contact-dependent mechanism to maintain sheet-integrity during migration, driving organ-morphogenesis. This is relevant for mesenchymal organ-sculpting in other migratory contexts like angiogenesis.
Harry McNamara (Assistant Professor of Molecular, Cellular and Developmental Biology, Yale University)
Title: Decoding and controlling self-organization in stem cell models of embryonic development
Abstract: The arrival of stem cell-based models of embryonic development (organoids, gastruloids, embryo models) presents new opportunities to investigate multicellular self-organization. Although development is often studied as a top-down process in which external spatial cues (such as morphogen gradients) instruct cell fate decisions, it is also thought that internal feedbacks in signaling networks can self-organize pattern formation from the bottom-up. Stem cell models use self-organization to generate cell types and tissue structures which resemble those built by real embryos. Despite rapid advances in stem cell model complexity and detailed comparisons to their in vivo counterparts, we have a comparatively limited understanding of how they emerge from cell signaling interactions. Unlocking the full potential of stem cell models will require not only characterizing their outputs but also understanding how they work.
We investigate stem cell self-organization by programming cells to read and write morphogen signals. By programming cells to record signaling activity, we can link early cell states to future cell fates and decode the origins of pattern formation. By controlling cell signaling with optogenetics, we can re-introduce spatial cues into stem cell models to guide morphogenesis and test predictions of quantitative theories. We will describe recent work applying this approach to study anterior-posterior symmetry breaking in the gastruloid as well as future opportunities in other stem cell developmental models.
- Speaker: Maik Christian Bischoff, UNC, Mark Peifer lab; Harry McNamara, Yale University
- Monday 02 June 2025, 14:30-15:30
- Venue: Online.
- Series: Morphogenesis Seminar Series; organiser: Jia CHEN.
Mon 12 May 14:30: Collective cell behaviors in mammalian intestinal morphogenesis
The mammalian intestinal epithelium undergoes constant renewal while simultaneously balancing cell fate decisions. In this talk, I will discuss our lab’s efforts in understanding how collective cell movement up the villus is regulated. Furthermore, I will describe our studies in how the intestinal stem cell niche, the crypt, forms postnatally and the role for epithelial-mesenchymal crosstalk in establishing the niche.
- Speaker: Kaelyn Sumigray, Department of Genetics at Yale School of Medicine
- Monday 12 May 2025, 14:30-15:30
- Venue: Online.
- Series: Morphogenesis Seminar Series; organiser: Jia CHEN.
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Wed 11 Jun 14:00: Exploring the Impact of Changing Overturning Circulation on Carbon Storage due to the Biological Carbon Pump: An Idealised Modelling Approach
Compelling evidence indicates that ocean circulation is undergoing significant changes due to global warming. These changes include reduced ocean ventilation caused by increased stratification and the weakening of the Atlantic Meridional Overturning Circulation (AMOC). Consequently, this will alter carbon, oxygen, heat and nutrient distribution, and will therefore affect primary production and, by extension, the biological carbon pump. Due to the ocean’s huge capacity for carbon storage, it is imperative that we understand the consequences of these changes.
To examine how ocean ventilation influences the biological carbon pump and overall oceanic carbon storage, an idealised box model of ocean carbon and heat uptake is extended to include biological processes and nutrient cycling. The model includes a thermocline with a dynamically controlled thickness and meridional overturning circulation, both of which vary with increasing temperatures, determining the extent of ocean ventilation. This model, previously employed to analyse the ocean’s carbon and thermal response to anthropogenic emissions, is now adapted to explore the effects of changing overturning on the biological carbon pump. A simple nutrient-phytoplankton-zooplankton-detritus (NPZD) biological model is introduced to simulate the role of macronutrient concentrations on phytoplankton and zooplankton growth. Simulations are conducted under scenarios of both constant and changing circulation to investigate the impacts of slower circulation on the biological carbon pump and its contribution to oceanic carbon storage.
- Speaker: Elisavet Baltas, University of Cambridge
- Wednesday 11 June 2025, 14:00-15:00
- Venue: BAS Seminar Room 2.
- Series: British Antarctic Survey - Polar Oceans seminar series; organiser: Dr Yohei Takano.
Wed 11 Jun 14:00: Title to be confirmed
Abstract not available
- Speaker: Elisavet Baltas, University of Cambridge
- Wednesday 11 June 2025, 14:00-15:00
- Venue: BAS Seminar Room 2.
- Series: British Antarctic Survey - Polar Oceans seminar series; organiser: Dr Yohei Takano.
Thu 22 May 16:00: Chasing Cracks on an Antarctic Ice Shelf
For this term we are celebrating fieldwork!
In this talk Emma will show us her expedition to the Brunt Ice Shelf in Antarctica
- Speaker: Emma Pearce
- Thursday 22 May 2025, 16:00-17:00
- Venue: Scott Polar Research Institute, main lecture theatre.
- Series: Scott Polar Research Institute - Polar Physical Sciences Seminar; organiser: meh91.
Thu 08 May 16:00: Crusing the South Shetland by Sail: In Search of Archaeology and Anything Green
For this term we are celebrating fieldwork!
In this talk Jeff will show us his travels about a sailing ship through the Southern Ocean
- Speaker: Jeff Kerby
- Thursday 08 May 2025, 16:00-17:00
- Venue: Scott Polar Research Institute, main lecture theatre.
- Series: Scott Polar Research Institute - Polar Physical Sciences Seminar; organiser: meh91.
Thu 15 May 16:00: Snow on the Edge: Marginal Snowpacks and Other Mediterranean Treasures
For this term we are celebrating fieldwork!
In this talk Konstantis will show off his winter work collecting data across the Alps
- Speaker: Konstantis Alexopolulos
- Thursday 15 May 2025, 16:00-17:00
- Venue: Scott Polar Research Institute, main lecture theatre.
- Series: Scott Polar Research Institute - Polar Physical Sciences Seminar; organiser: meh91.