Project Outline

How does the heart form? Despite the large array of adult heart morphologies across nature, the initial heart vessel typically forms as a simple tubular structure. Further, the genetic network underlying the specification of the early embryonic heart is highly conserved across species.¹

In this project, we will use the power of Drosophila genetics and live imaging to unravel the fundamental mechanical and genetic mechanisms driving the formation of the initial heart vessel.^2-4 We will tackle two major questions: (1) how does the first lumen in the heart form; and (2) how are the aorta and heart mechanically separated?

The first aim will be to develop imaging approaches to enable imaging of the embryonic heart formation in vivo. This will involve using a range of microscopes (spinning disc, 2-photon, light-sheet). Combined with advanced image analysis methodologies,⁵ this exciting approach will enable unprecedented insight into the dynamics of the formation of the initial heart structure. As part of the project, there will be opportunities to perform experiments at the MRC LMB in Cambridge with our collaborator Kate McDole. This will use light-sheet microscopy. The student will explore which mechanical components (e.g., cell cytoskeleton, filopodia, actin, microtubules) are essential in building the early heart vessel. We will initially focus on identifying how perturbations to, for example, cadherins, alter the dynamics of heart lumen formation. The student will build the first in vivo and dynamic atlas of the processes underlying the formation of the embryonic heart lumen. Finally, we will use our knowledge developed to explore how the heart vessel is separated into the heart (pump) and the aorta. What are the processes driving formation of the differentiated heart structures?

This PhD project offers an exciting opportunity to leverage recent advances in live imaging and genetics to gain unprecedented insights into how a critical organ forms during development, with potential impact on human development.

This project is a truly interdisciplinary project, ideally suited for either (a) a trained biologist interested in developing their expertise in quantitative approaches or (b) a physicist or engineer (preferably with some optics experience) interested in applying the latest microscopy approaches to important biological systems.

Methodologies that will be developed as part of the project:

1. Drosophila genetics. This will include learning to perform crossing and generating new lines (potentially including CRISPR approaches)
2. Live imaging. We will utilise multiphoton microscopy and light-sheet microscopy to gain a subcellular view of how the heart initially forms
3. Image analysis. Taking data from our microscopy and generating quantitative data is essential. In particular, we want to understand the specific developmental time when morphological changes occur
4. Mechanobiology approaches to understanding cell function and morphology

The Saunders lab is a highly interdisciplinary environment, with biologists and physicists working together to tackle major questions concerning how organs form. The McDole lab is world-leading in imaging developing systems at cellular resolution. This project offers a motivated student the opportunity to learn a breadth of techniques in quantitative biology that have broad applicability. It will run in parallel with the lab’s British Heart Foundation supported research dissecting the genetics of heart formation.

References

1. Olson EN, Gene regulatory networks in the evolution and development of the heart. Science 2006; 313: 1922
2. Zhang S, Amourda C, Garfield D and Saunders TE. Selective filopodia adhesion ensures robust cell matching in the Drosophila heart. Developmental Cell 2018; 46: 189
3. Zhang S, Teng X, Toyama Y, and Saunders TE. Periodic Oscillations of Myosin-II Mechanically Proofread Cell-Cell Connections to Ensure Robust Formation of the Cardiac Vessel. Current Biology 2020; 30: 3364
4. Zhang S and Saunders TE. Mechanical processes underlying precise and robust cell matching. Seminars in Cell and Developmental Biology 2021, in press
5. Stringer C, Wang T, Michaelos M and Pachitariu M. Cellpose: a generalist algorithm for cellular segmentation 2021; 18: 100

Techniques

• Drosophila husbandry
• Drosophila genetics
• Confocal and other light microscopy
• Biophysical perturbation, e.g., laser ablation
• Image analysis tools, including Fiji and CellPose2.0
• Statistical analysis