Interplay between tissue material properties and acquisition of cell fate during development

During zebrafish early development, the cell mass transitions from a pluripotent state to a patterned embryo. Intriguingly, regions of different fates correspond to regions of different tissue material properties. Using genetic mutants with altered tissue material properties and optogenetic manipulations to interfere with cell to tissue scale architecture, Camilla investigates functional links and possible mechanisms of a co-regulation between the tissue material state and cell fate decisions. 

About the scientist: Camilla holds a bachelor degree in Biology from the University of Rome “La Sapienza” (Italy). She broadened her experience in developmental biology during her master in Molecular Biosciences with a major in Developmental and Stem Cells Biology at the Heidelberg University. During this time she did internships in the labs of Lazaro Centanin (COS – Heidelberg), Marco Milan (IRB – Barcelona) and her master thesis on the evolution of germ band extension in flies and midges in the lab of Steffen Lemke (COS – Heidelberg). She then joined the Petridou lab in 2020 as a PhD student. 

The impact of cell division synchronicity on the tissue material state

Early embryonic development in metazoans commonly starts in cell cycle synchrony, but cell division synchrony ceases before major morphogenetic events take place (see movie). Although cell cycle dynamics are regulated at the single cell level, the cell-to-cell desynchronization observed in early embryos elicits collective effects, including shape and pattern formation. In this PhD project, Lena tries to understand the interplay of cell cycle synchrony and the tissue material state in the early zebrafish embryo.

About the scientist: Originally from Austria, Lena has completed her undergraduate studies in Biochemistry at McGill University (Montreal, Canada). There, she was first in contact with developmental morphogenesis through the lab of Maxime Bouchard, working on the formation of the ureter-bladder connection during mouse development. She then continued her studies at the University of Cambridge in the lab of Thorsten Boroviak (Cambridge, United Kingdom) working on culture of human stem cell spheroids. Lena then started her PhD at the Petridou group in 2020. Find Lena on LinkedIn and X.

The Role of different Material Phase Transitions in Shaping Tissue Organization

Zebrafish early embryos undergo dramatic changes in their material properties, which critically influence their morphogenesis. By developing optogenetic techniques and implementing genetic mutants alongside pharmacological interventions, Cristina can manipulate the key parameters that govern these tissue properties (see image: Sagittal view of a wild-type D. rerio embryo during gastrulation compared to an optogenetically fluidized embryo at the same developmental stage). Cristina and Laura teamed up to explore how different material phase transitions contribute to the overall tissue architecture using these approaches. Cristina further supports the group by optimising new methods including transcriptomics and metabolomics.

About the Scientist: Cristina is a Biologist who graduated from the University of Barcelona (UB), where she developed a strong interest in Developmental Biology. Her early research at UB’s Genetics Department focused on the role of Selenoproteins in Drosophila melanogaster. After completing her Ph.D., Cristina expanded her expertise in growth regulation and metabolism at the German Cancer Research Center (DKFZ). Cristina then joined the De Renzis group at EMBL as a research technician, working with optogenetic tools in Drosophila, embracing a Synthetic Biology approach to Developmental Biology questions. Since 2020, she has been a Scientific Officer in the Petridou group.

The emergence and function of different types of tissue material phase transitions during embryo development

Laura is interested in how cells sense and respond to different tissue material states and their changes. She is characterising both responses at short timescales (e.g. cellular dynamics, see movie) and at long timescales (e.g. gene expression changes). Additionally, Laura is exploring together with Cristina the different types of material phase transitions, how they can be triggered, and what their role is.

About the scientist: Laura completed her Biology undergraduate studies at Heidelberg University (Germany), where she became interested in developmental biology and signalling while working on Hydra tentacle formation in the lab of Thomas Holstein. She then worked with trypanosomes during an internship in the lab of Paula MacGregor at the University of Cambridge (UK). Afterwards, Laura did a Master’s at Freiburg University (Germany), focusing on developmental biology and working in the lab of Wolfgang Driever, where she worked on Yap/Taz signalling in zebrafish embryonic neural stem cells. Laura started her PhD at the Petridou group in 2021. Find Laura on LinkedIn and X.

Shine a Light on Epithelial-to-Mesenchymal (EMT) Phase Transition

EMT is a key process common in embryonic development as well as cancer initiation and metastasis. Despite our knowledge in transcriptional drivers and mechanical elements regulating EMT, how molecular states interplay with biophysical parameters when cells initiate, progress, and exit EMT is not fully understood. For her EIPOD project, Yuting integrates the phase transition theory, tissue material state profiling, and light-induced spatial barcoding technology (collaborating with Sinem Saka group) to decode EMT mechanisms from microscopic (molecular, cellular) to macroscopic (tissue) levels.

About the scientist: Following her BSc (Zhejiang University, China) training in Biomedical Science, Yuting did her MSc and PhD research in the lab of Liz Patton at the Institute of Genetics and Cancer, University of Edinburgh (UK). Yuting started her postdoctoral research at the Petridou group in 2024.

Energetic cost and regulation of tissue phase transitions 

Tissue material phase transitions, such as solidification and fluidization, are regulated by cell parameters like density, motility and contact formation. Intriguingly, in physics, solidification vs fluidization are energetically different processes (exothermic vs endothermic) and similarly in tissues, the cell parameters that control the material state have a certain energetic demand. However, what are the energetic costs of different material phase transitions and what is the interplay with metabolism is yet unknown. During her EIPOD project in collaboration with the groups of Aulehla (EMBL- Heidelberg) and Rodenfelds (MPI-CBG – Dresden), Jlenia combines quantitative imaging analysis, metabolic profiling, biophysics and zebrafish and killifish embryology to uncover the mechano-metabolic principles underlying PTs.

About the scientist: Jlenia obtained her bachelor’s degree in Biology from the University of Piemonte Orientale “Amedeo Avogadro” in Italy. She then pursued a master degree in Functional Genomics at the University of Trieste. During her master thesis, she worked on cancer at the Regina Elena Cancer Institute in Rome, in the lab of Giovanni Blandino. For her PhD, Jlenia shifted her focus to studying the biogenesis of the nuclear pore complex (NPC) and spindle pole body (SPB) in yeast at the Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH) in the lab of Elmar Schiebel. Jlenia started her postdoc in the Petridou group in 2023.

The role of biophysical properties on the specification and function of the vertebrate organiser

The vertebrate organiser is crucial to develop the germ layers, pattern the body axes and initiate gastrulation. While we understand the signalling pathways and gene regulatory networks that specify and enable the functions of the organiser we do not know much about its biophysical properties. My project will use comparative embryological approaches, using killifish and zebrafish embryos (see movie, organiser labelled in green, cell membrane in red and interstitial fluid in cyan blue), to investigate how the physical properties of the cell, tissue and the in vivo environment can influence the structure and function of the vertebrate organiser.

About the Scientist: Karen obtained her bachelor’s degree in Chemistry from St. Stephen’s College, Delhi University, India. She then switched to studying biology, obtaining a Master’s by research in biology from the Tata Institute of Fundamental Research, Mumbai, India in the lab of Dr. Maithreyi Narasimha. During this three year program she studied the role of Notch signalling in patterning cell delamination during morphogenesis in the Drosophila embryo. Karen then obtained a PhD from the Max Planck Institute of Molecular Cell Biology and Genetics (MPI-CBG), Dresden, using the zebrafish optic cup to investigate the role of extracellular matrix topology on collective cell migration in vivo. She was a shared predoc in the labs of Dr. Caren Norden at MPI-CBG and Dr. Carl Modes at the Center for Systems Biology Dresden (CSBD). She joined the Petridou lab in 2024. Find Karen on LinkedIn. Karen is also a published poet and you can find her work at doodlinscientist.com.

Emergence and function of interstitial fluid compartment during vertebrate gastrulation

All embryonic cells are surrounded by extracellular fluid, whose properties serve diverse physical and chemical roles during organismal development. Extracellular Fluid Compartments (EFCs) greatly vary concerning their chemical composition, shape, size and dynamics, ranging from well-organized ordered structures, like extracellular matrix (ECM) and lumens, to the less-organized disordered interstitial spaces. Although ordered-EFCs have been for long identified as essential components of embryonic development, our knowledge of the emergence and function of disordered-EFCs is limited. Jun-Ru’s project aims to use a comparative approach in combination with quantitative live imaging, biophysical and biochemical assays to understand the function and formation of interstitial fluid in several teleost species.  

About the Scientist: Jun-Ru obtained his bachelor’s and master’s degrees from National Taiwan University, Taiwan. His master thesis focused on cell migration in leech embryo development. After a short stay at Academia Sinica, he then pursued his PhD at Max Planck Institute for Multidisciplinary Sciences, Goettingen, focusing on cell turnover in the planarian epidermis. Jun-Ru joined the Petridou lab as a postdoctoral researcher in 2024 .