During development, organisms interact with their natural habitats while undergoing morphological changes, yet we know little about how the interplay between developing systems and their environments impacts animal morphogenesis. Cnidaria, a basal animal lineage that includes sea anemones, corals, hydras, and jellyfish, offers unique insight into the development and evolution of morphological complexity. In my talk, I will introduce our research on “ethology of morphogenesis,” a concept that links the behavior of organisms to the development of their size and shape at both cellular and biophysical levels, opening new perspectives about the design principle of soft-bodied animals. In addition, I will discuss a fascinating feature of cnidarian biology. For humans, our genetic code determines that we will grow two arms and two legs. The same fate is true for all mammals. Similarly, the number of fins of a fish or legs and wings of an insect is embedded in their genetic code. I will describe how sea anemones defy this rule.

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• Speaker: Aissam Ikmi
• Monday 29 November 2021, 14:30-15:30
• Venue: Online.
• Series: Morphogenesis Seminar Series; organiser: .

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During development, organisms interact with their natural habitats while undergoing morphological changes, yet we know little about how the interplay between developing systems and their environments impacts animal morphogenesis. Cnidaria, a basal animal lineage that includes sea anemones, corals, hydras, and jellyfish, offers unique insight into the development and evolution of morphological complexity. In my talk, I will introduce our research on “ethology of morphogenesis,” a concept that links the behavior of organisms to the development of their size and shape at both cellular and biophysical levels, opening new perspectives about the design principle of soft-bodied animals. In addition, I will discuss a fascinating feature of cnidarian biology. For humans, our genetic code determines that we will grow two arms and two legs. The same fate is true for all mammals. Similarly, the number of fins of a fish or legs and wings of an insect is embedded in their genetic code. I will describe how sea anemones defy this rule.

Join the mailing list for the zoom link https://lists.cam.ac.uk/mailman/listinfo/ucam-morphogenesis-series

• Speaker: Aissam Ikmi
• Monday 29 November 2021, 14:30-15:30
• Venue: Online.
• Series: Morphogenesis Seminar Series; organiser: .

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Matteusz Trylinski Coordination of cellular behaviours enables both the formation of tissues and complex organs during development and the appearance of new structures during evolution. One of such events is the emergence of glial wrapping during Metazoan history, which among others increased the speed and the precision of information transfer along axons. Although we have a good understanding on the current mechanisms regulating this process, little is known about their evolutionary origin. Here, we address this question by using an evolutionary-conserved sensory organ, the Drosophila thoracic microchaete. These organs are made of four lineage-related cells – two outer structural cells and two inner sensory cells – that are organised in a concentric, or “onion-like”, fashion. Given that homologous structures can be found in Tardigrades, which have diverged from Arthropods over 500 million years ago, we speculate that the mechanisms involved in the successive ensheathments during microchaete morphogenesis might be reminiscent of the ancestral state. In particular, we investigate how, following the first lineage division that gives rise to the outer-cell and inner-cell progenitors, the future structural-sensory interface is generated, and how the inner-cell progenitor is enwrapped by the outer-cell progenitor. Our preliminary results suggest that this wrapping event combines both non-transcriptional effectors related to asymmetric cell division and transcriptional targets expressed by the inner-cell progenitor.

Renske Vroomans Most multicellular organisms undergo some form of development and morphogenesis. Recent studies have shown that many of the genetic tools to regulate these processes were already present in their unicellular ancestor. This suggests that the most ubiquitous developmental processes may also be traced back all the way to the emergence of multicellularity itself. Furthermore, the evolutionary transition to multicellularity may have predominantly required changes in regulation and coordination, more than changing the gene content. We use evolutionary models to study the evolution of cell adhesion and gene regulation at the onset of multicellularity. We find that the physical properties of cell clusters can be sufficient to drive selection for cell adhesion. Once cells evolve adhesion however, their regulatory dynamics evolve as well: while cells evolve adhesion to survive collectively, within such cohesive clusters, intercellular competition drives cells to behave “selfishly” by dividing sooner and perform the collective task later. The model demonstrates how the transition to multicellularity may have driven a drastic switch in cell behaviour, leading to complex coordinated dynamics compared to the unicellular cousins, without changing the genetic toolkit.

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• Speaker: Renske Vroomans; Matteusz Trylinski
• Monday 25 October 2021, 14:30-15:30
• Venue: Online.
• Series: Morphogenesis Seminar Series; organiser: sarah.robinson.

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Matteusz Trylinski Coordination of cellular behaviours enables both the formation of tissues and complex organs during development and the appearance of new structures during evolution. One of such events is the emergence of glial wrapping during Metazoan history, which among others increased the speed and the precision of information transfer along axons. Although we have a good understanding on the current mechanisms regulating this process, little is known about their evolutionary origin. Here, we address this question by using an evolutionary-conserved sensory organ, the Drosophila thoracic microchaete. These organs are made of four lineage-related cells – two outer structural cells and two inner sensory cells – that are organised in a concentric, or “onion-like”, fashion. Given that homologous structures can be found in Tardigrades, which have diverged from Arthropods over 500 million years ago, we speculate that the mechanisms involved in the successive ensheathments during microchaete morphogenesis might be reminiscent of the ancestral state. In particular, we investigate how, following the first lineage division that gives rise to the outer-cell and inner-cell progenitors, the future structural-sensory interface is generated, and how the inner-cell progenitor is enwrapped by the outer-cell progenitor. Our preliminary results suggest that this wrapping event combines both non-transcriptional effectors related to asymmetric cell division and transcriptional targets expressed by the inner-cell progenitor.

Renske Vroomans Most multicellular organisms undergo some form of development and morphogenesis. Recent studies have shown that many of the genetic tools to regulate these processes were already present in their unicellular ancestor. This suggests that the most ubiquitous developmental processes may also be traced back all the way to the emergence of multicellularity itself. Furthermore, the evolutionary transition to multicellularity may have predominantly required changes in regulation and coordination, more than changing the gene content. We use evolutionary models to study the evolution of cell adhesion and gene regulation at the onset of multicellularity. We find that the physical properties of cell clusters can be sufficient to drive selection for cell adhesion. Once cells evolve adhesion however, their regulatory dynamics evolve as well: while cells evolve adhesion to survive collectively, within such cohesive clusters, intercellular competition drives cells to behave “selfishly” by dividing sooner and perform the collective task later. The model demonstrates how the transition to multicellularity may have driven a drastic switch in cell behaviour, leading to complex coordinated dynamics compared to the unicellular cousins, without changing the genetic toolkit.

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• Speaker: Renske Vroomans; Matteusz Trylinski
• Monday 25 October 2021, 14:30-15:30
• Venue: Online.
• Series: Morphogenesis Seminar Series; organiser: sarah.robinson.

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During pattern formation, morphogenetic events provide a response of the naïve tissue to chemical and mechanical positional cues. To what extent these processes shape pattern establishment and contribute to natural variation remains unclear. We studied cell dynamics occurring during the emergence of feather array geometries in birds, which involves a gradual regionalisation of the skin through self-organisation. We identified highly dynamic modifications of local cell density, movement, and shape occurring during primordia emergence in the Japanese quail. Using inter-species comparison in poultry, finch, emu, ostrich and penguin embryos, followed by perturbation of skin architecture ex vivo, we showed that oriented anisotropy of dermal cells prior to primordia formation is necessary for the regularity of the final array. Our results provide key insights into the cellular basis of self-organisation and demonstrate that initial tissue morphology constrains pattern attributes, uncovering a morphogenetic mechanism contributing to pattern evolution.

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• Speaker: Marie Manceau
• Monday 01 November 2021, 14:30-15:30
• Venue: Online.
• Series: Morphogenesis Seminar Series; organiser: margherita battistara.

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During pattern formation, morphogenetic events provide a response of the naïve tissue to chemical and mechanical positional cues. To what extent these processes shape pattern establishment and contribute to natural variation remains unclear. We studied cell dynamics occurring during the emergence of feather array geometries in birds, which involves a gradual regionalisation of the skin through self-organisation. We identified highly dynamic modifications of local cell density, movement, and shape occurring during primordia emergence in the Japanese quail. Using inter-species comparison in poultry, finch, emu, ostrich and penguin embryos, followed by perturbation of skin architecture ex vivo, we showed that oriented anisotropy of dermal cells prior to primordia formation is necessary for the regularity of the final array. Our results provide key insights into the cellular basis of self-organisation and demonstrate that initial tissue morphology constrains pattern attributes, uncovering a morphogenetic mechanism contributing to pattern evolution.

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• Speaker: Marie Manceau
• Monday 01 November 2021, 14:30-15:30
• Venue: Online.
• Series: Morphogenesis Seminar Series; organiser: margherita battistara.

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Although cell-to-cell heterogeneity in gene and protein expression within cell populations has been widely documented, we know little about its biological functions. By studying progenitors of the posterior region of bird embryos, we found that expression levels of transcription factors Sox2 and Bra, respectively involved in neural tube and mesoderm specification, display a high degree of cell-to-cell heterogeneity. By combining forced expression, and downregulation approaches with time-lapse imaging we demonstrate that Sox2-to-Bra ratio guides progenitor’s motility and their ability to stay in or exit the progenitor zone to integrate neural or mesodermal tissues. Indeed, high Bra levels confer high motility that pushes cells to join the paraxial mesoderm, while high levels of Sox2 tend to inhibit cell movement forcing cells to integrate the neural tube. Mathematical modelling captures the importance of cell motility regulation in this process and further suggests that randomness in Sox2/Bra cell-to-cell distribution favors cell rearrangements and tissue shape conservation.

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• Speaker: Bertrand Benazeraf
• Monday 15 November 2021, 14:30-15:30
• Venue: Online.
• Series: Morphogenesis Seminar Series; organiser: ldt31.

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Although cell-to-cell heterogeneity in gene and protein expression within cell populations has been widely documented, we know little about its biological functions. By studying progenitors of the posterior region of bird embryos, we found that expression levels of transcription factors Sox2 and Bra, respectively involved in neural tube and mesoderm specification, display a high degree of cell-to-cell heterogeneity. By combining forced expression, and downregulation approaches with time-lapse imaging we demonstrate that Sox2-to-Bra ratio guides progenitor’s motility and their ability to stay in or exit the progenitor zone to integrate neural or mesodermal tissues. Indeed, high Bra levels confer high motility that pushes cells to join the paraxial mesoderm, while high levels of Sox2 tend to inhibit cell movement forcing cells to integrate the neural tube. Mathematical modelling captures the importance of cell motility regulation in this process and further suggests that randomness in Sox2/Bra cell-to-cell distribution favors cell rearrangements and tissue shape conservation.

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• Speaker: Bertrand Benazeraf
• Monday 15 November 2021, 14:30-15:30
• Venue: Online.
• Series: Morphogenesis Seminar Series; organiser: ldt31.

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Jamie McGinn Mounting evidence suggests that epithelial stem cells are more dynamic than originally thought. Stem cell behaviour is not a discrete state as it can be re-gained by differentiating cells as a result of tissue challenges such as injury and tumorigenesis. This plasticity may explain why, despite decades of intensive research in epithelial stem cell biology, the field still debates about the identity of the cell populations contributing to the homeostasis and repair of squamous tissues. In order to fully unveil the rules governing epithelial cell behaviour, it is critical to understand the dynamic nature of epithelial cells by exploring their response to situations away from homeostasis. In this study we investigate the cell fate transitions taking place in the mouse squamous oesophageal epithelium from birth until the onset of adult homeostasis, as a physiological model of rapid but restricted tissue growth. Observations throughout post-natal development show that oesophageal expansion after birth occurs in a biphasic pattern, with a fast initial growth that slows down before reaching adult tissue size. This turning point is characterized by a range of changes in the expression of key developmental factors, defining the transition of cell fate identity in the basal progenitor cell compartment. The establishment of homeostatic oesophageal features coincide with significant changes in tissue architecture, including tissue strain and decreased cell density. Remarkably, tissue stretching experiments reveal that the mechanical changes experienced by the developing oesophageal epithelium after birth are critical for shifting the rapid growing tissue into a homeostatic mode.

Ben Steventon As cells proceed through development, information contained in the genome is expressed in a context-dependent manner. This must be regulated precisely in both space and time to generate patterns of gene expression that set-up the spatial coordinates of tissue and organ primordia that build the embryo. Our current understanding of pattern formation relies on the concept of positional information, the idea that cells receive instructive signals that impart a spatial coordinate system to generate pattern. While this model works very well in static cell populations with minimal cell rearrangement, it becomes challenging when considering dynamic morphogenetic processes such as gastrulation. Furthermore, pattern formation in gastrulation is highly flexible to alterations in the size, scale and spatial rearrangement of cells in both experimental and evolutionary situations. Our work seeks to provide illustrations of two concepts that will help resolve these long-standing problems of pattern regulation, evolvability and self-organisation. Firstly, downward causation emphasises the role that multi-tissue interactions play in relaying information from changes at the organ and organism level to the regulation of gene regulatory networks (GRNs) at the cell level. Secondly, pattern emergence considers how extracellular signals act to control the dynamics of autonomous GRN activity, rather than as instructive signals to direct cell fate transitions. In this sense, we propose that pattern formation should not be seen as a downstream output of organisers and their responding tissues, but rather as an emergent property of their dynamic interaction.

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• Speaker: Ben Steventon, Jamie McGinn
• Monday 08 November 2021, 14:30-15:30
• Venue: Online.
• Series: Morphogenesis Seminar Series; organiser: ldt31.

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Jamie McGinn Mounting evidence suggests that epithelial stem cells are more dynamic than originally thought. Stem cell behaviour is not a discrete state as it can be re-gained by differentiating cells as a result of tissue challenges such as injury and tumorigenesis. This plasticity may explain why, despite decades of intensive research in epithelial stem cell biology, the field still debates about the identity of the cell populations contributing to the homeostasis and repair of squamous tissues. In order to fully unveil the rules governing epithelial cell behaviour, it is critical to understand the dynamic nature of epithelial cells by exploring their response to situations away from homeostasis. In this study we investigate the cell fate transitions taking place in the mouse squamous oesophageal epithelium from birth until the onset of adult homeostasis, as a physiological model of rapid but restricted tissue growth. Observations throughout post-natal development show that oesophageal expansion after birth occurs in a biphasic pattern, with a fast initial growth that slows down before reaching adult tissue size. This turning point is characterized by a range of changes in the expression of key developmental factors, defining the transition of cell fate identity in the basal progenitor cell compartment. The establishment of homeostatic oesophageal features coincide with significant changes in tissue architecture, including tissue strain and decreased cell density. Remarkably, tissue stretching experiments reveal that the mechanical changes experienced by the developing oesophageal epithelium after birth are critical for shifting the rapid growing tissue into a homeostatic mode.

Ben Steventon As cells proceed through development, information contained in the genome is expressed in a context-dependent manner. This must be regulated precisely in both space and time to generate patterns of gene expression that set-up the spatial coordinates of tissue and organ primordia that build the embryo. Our current understanding of pattern formation relies on the concept of positional information, the idea that cells receive instructive signals that impart a spatial coordinate system to generate pattern. While this model works very well in static cell populations with minimal cell rearrangement, it becomes challenging when considering dynamic morphogenetic processes such as gastrulation. Furthermore, pattern formation in gastrulation is highly flexible to alterations in the size, scale and spatial rearrangement of cells in both experimental and evolutionary situations. Our work seeks to provide illustrations of two concepts that will help resolve these long-standing problems of pattern regulation, evolvability and self-organisation. Firstly, downward causation emphasises the role that multi-tissue interactions play in relaying information from changes at the organ and organism level to the regulation of gene regulatory networks (GRNs) at the cell level. Secondly, pattern emergence considers how extracellular signals act to control the dynamics of autonomous GRN activity, rather than as instructive signals to direct cell fate transitions. In this sense, we propose that pattern formation should not be seen as a downstream output of organisers and their responding tissues, but rather as an emergent property of their dynamic interaction.

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• Speaker: Ben Steventon, Jamie McGinn
• Monday 08 November 2021, 14:30-15:30
• Venue: Online.
• Series: Morphogenesis Seminar Series; organiser: ldt31.

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Abstract not available

• Speaker: Professor Bhaskar Vira, University of Cambridge
• Friday 11 March 2022, 17:30-18:30
• Venue: Lady Mitchell Hall, Sidgwick Avenue.
• Series: Darwin College Lecture Series; organiser: Janet Gibson.

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Abstract not available

• Speaker: Professor Martin Jones, University of Cambridge
• Friday 04 March 2022, 17:30-18:30
• Venue: Lady Mitchell Hall, Sidgwick Avenue.
• Series: Darwin College Lecture Series; organiser: Janet Gibson.

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Abstract not available

• Speaker: Mr Alex Rushmer, Chef
• Friday 18 February 2022, 17:30-18:30
• Venue: Lady Mitchell Hall, Sidgwick Avenue.
• Series: Darwin College Lecture Series; organiser: Janet Gibson.

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Abstract not available

• Speaker: Mr Richard Parmee, University of Cambridge
• Friday 11 February 2022, 17:30-18:30
• Venue: Lady Mitchell Hall, Sidgwick Avenue.
• Series: Darwin College Lecture Series; organiser: Janet Gibson.

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Abstract not available

• Speaker: Ms Sarah Mukherjee, Journalist
• Friday 04 February 2022, 17:30-18:30
• Venue: Lady Mitchell Hall, Sidgwick Avenue.
• Series: Darwin College Lecture Series; organiser: Janet Gibson.

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Abstract not available

• Speaker: Professor Andrew Knight, University of Winchester
• Friday 28 January 2022, 17:30-18:30
• Venue: Online.
• Series: Darwin College Lecture Series; organiser: Janet Gibson.

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Abstract not available

• Speaker: Professor Sarah Bridle, University of Manchester
• Friday 21 January 2022, 17:30-18:30
• Venue: Online.
• Series: Darwin College Lecture Series; organiser: Janet Gibson.

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Abstract not available

• Speaker: Professor Bhaskar Vira
• Friday 11 March 2022, 17:30-18:30
• Venue: Lady Mitchell Hall, Sidgwick Avenue.
• Series: Darwin College Lecture Series; organiser: Janet Gibson.

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Abstract not available

• Speaker: Professor Martin Jones
• Friday 04 March 2022, 17:30-18:30
• Venue: Lady Mitchell Hall, Sidgwick Avenue.
• Series: Darwin College Lecture Series; organiser: Janet Gibson.

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Abstract not available

• Speaker: Mr Alex Rushmer
• Friday 18 February 2022, 17:30-18:30
• Venue: Lady Mitchell Hall, Sidgwick Avenue.
• Series: Darwin College Lecture Series; organiser: Janet Gibson.

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