Investigation of the mechanics of gastrulation in the chick embryo using new transgenic chicken lines

Abstracts are not currently available in GtR for all funded research. This is normally because the abstract was not required at the time of proposal submission, but may be because it included sensitive information such as personal details.

This study aims to analyse and model the mechanisms that quantitatively coordinate key epiblast cell behaviours that drive primitive streak formation in the chick embryo. Previous work has shown that tissue flows are driven by myosin dependent directed cell intercalations in conjunction with apical contraction and ingression of mesendoderm cells. Now we will investigate the mechanism by which forces generated by these complex cell behaviours can organise the spatio-temporal coordination of cell divisions, ingressions and intercalations of hundreds of thousands of epiblast cells to drive the embryo wide tissue flows. Specifically, we will investigate whether mechano-sensitive myosin accumulation and activation organises the observed large scale orientation of cell intercalations and characterise the mechano-transduction pathways involved. We will investigate how cell behaviour generated tension drives the balance of cell divisions and ingressions through the streak and out with the streak to achieve cellular homeostasis of the embryonic region during streak formation. We will initiate an analysis of how mechanical feedback is involved in the control of gene expression controlling cell behaviours and differentiation. This work will be based on our recent advances in light sheet microscopy, quantitative large scale data analysis, and the local and large scale biological, chemical and physical manipulation of cells and tissues. The work will also rely heavily on the generation of novel knockin chick lines where critical components of the actin myosin cytoskeleton are endogenously labelled and knocked out using a highly innovative avian transgenesis and gene editing platform. This will establish the chick as a power full amniote model system that combines easy of live culture and experimental accessibility of embryos with extensive and cost effective genetic manipulation.

The research proposed here investigates the mechanisms governing gastrulation, a central process in the development of all higher animals. It makes use of state of the art long term lightsheet microscopy, advanced large scale automated image processing, data analysis and mathematical modelling in combination with novel transgenesis and gene editing techniques to study gastrulation in the chick embryo. Our work focusses on elucidating the mechano-chemical mechanisms that coordinate individual cell behaviours such as division, ingression and intercalation of a large population of hundreds of thousands of differentiating cells to generate and organise complex tissues at the organism scale. Findings made here will greatly increase our understanding of the development, the origin and causes of many congenital defects associated with early development, e.g. spina bifida, partial twinning, heart and vasculature defects and should be of interest to researchers working on these problems.
This research will advance the establishment of the chick embryo as a key model system to study amniote development, by a combination of experimental accessibility of the embryo, which allows detailed analysis of dynamic processes at the cell and tissue level over extended periods of time, with the ability to genetically tag and precisely manipulate individual key components of the gene regulatory, signalling and executing systems involved, hitherto only available in invertebrates and lower vertebrates such as amphibians and fish. Furthermore, the availability of another genetically tractable relatively cost effective model system besides mice is a pre-requisite for a comparative approach necessary to distinguish generic characteristic from species specific adaptations of the mechanism that drive gastrulation in amniotes. This should be of interest to many researchers working at different aspects of amniote development and development in general.
Key processes of gastrulation such as directed collective migration, tissue deformation, ingression and EMT are also central to other biological processes using similar cellular mechanisms like wound healing, tissue repair and regeneration. Failure to properly control these is key to the development of autoimmune diseases and metastasis of cancer cells. Therefore findings made here will be directly relevant to researchers in these areas.
Understanding these developmental processes is also essential for the rational use of embryonic stem cells in regenerative medicine. It is by no means clear how embryonic stem cells migrate to the right positions and organise themselves to repair defects in-situ. Clearly, successful manipulation of stem cells will require understanding of directed cell migration, cell-cell interactions and interactions between behaviour and signalling. Therefore, in the longer term, the research proposed is expected to have practical applications in these increasingly important areas of medicine and healthcare, affecting researchers and practitioners in both the academic and the commercial sector. Life science research activities in Dundee are already responsible for 16% of the Tayside economy.
The project will train a number of young researchers (PDRAs and PhD students) in a unique combination of live imaging, computational data analysis, modelling and advanced transgenesis and gene editing methods.
Insights and materials (movies of development) acquired in this research are already extensively used in lectures for undergraduate and postgraduate students by us and colleagues. Gastrulation is core material in many Life Sciences and Medical textbooks and key research findings made here will become textbook material for medical and life sciences.
This research generates exquisite experimental and computational images that have and will be part of exhibitions at the local, national and international level and will stimulate further interactions with branches of the creative industries.