Photo of me

Rhoda J Hawkins


Research interests

University of Sheffield logo
Department of Physics and Astronomy
Home
Research
People
Vacancies
Publications
Biography
Administration
Teaching
Our research is in theoretical biological physics. We use approaches from theoretical physics to study biological and biologically inspired systems. We seek to describe biological processes using the powerful language of mathematics and aim to explain how physical principles act in living systems. We develop simple models, allowing analytical results where possible and using computational simulations where necessary to retain sufficient detail to describe behaviour seen in experiments. To do this we work in collaboration with scientists from a range of disciplines including biology and medicine. This page outlines some of the areas we are interested in. Please see our publications for more details of work we have already done.

Active matter

"Active matter" is material that is out of equilibrium due to its constitutive components having an internal source of energy that drives the system out of equilibrium. From a physics perspective active matter is a novel type of material that displays rich and interesting behaviours. Active gel theory uses equations developed for viscoelastic gels or liquid crystals and adds terms to describe the "active" out-of-equilibrium nature of materials such as those found in living systems and synthetic active materials.

Cytoskeleton

Active matter theory can be used to model the cytoskeleton of living cells. The cytoskeleton is a biopolymer network made of filamentous proteins such as actin and microtubules shown in read and green in the picture below.
Image of the Cytoskeleton
We are particularly interested in actomyosin cytoskeleton made up of actin filaments and myosin molecular motors. By consuming chemical fuel (ATP) the actin filaments grow (polymerise) and the molecular motors can walk along the filaments exerting stress on the actin filaments. The overall effect of the stress exerted by myosin on actin is contraction.

Cell migration

The dynamics of the cytoskeleton drive cell deformation and movement. Using active matter theory to model the cytoskeleton, we seek to better understand the mechanics of cell migration. How do the active properties of the cytoskeleton biological gel enable cells to move independently in a way that non-living gels like hair gel don't?

We are particularly interested in cell motility in confinement. Cells sometimes have to squeeze though small gaps, for example immune cells chasing bacteria or metastatic cancer cells exiting a tumour and moving to form a secondary tumour elsewhere. We develop theoretical models of cell migration in confinement in collaboration with experimentalists in Paris (primarily Matthieu Piel's lab).
Pushing off the walls model
For example some years ago we developed an initial simple model for a mechanism for cell motility in confinement which works in a similar way to a rock climber using a technique called "chimneying". The climber pushes against two opposing rock faces in order to gain the friction needed to climb. In a similar way the cell in our mechanism pushes against the confining walls to create the friction needed to move.

Cell nucleus

The cell nucleus contains the DNA (shown in blue in the image above). When cells squeeze through particularly small gaps the nucleus has to change shape to get through. We are interested in this and other scenarios when the nucleus is deformed. We model the nucleus as an elastic object and calculate the forces required to deform it. Some of the questions we consider are: How does the cell generate the forces needed to push/pull the nucleus? What is the physical role of the nucleus in cell migration? How does the cytoskeleton active gel interact with the nucleus? We have received funding for this work from EPSRC and collaborated with Matthieu Piel and Denis Wirtz labs.

Image of Nucelus Deformation

Metastatic cancer cells

We are interested in using what we have learnt about cell migration in confined environments and the role of the nucleus to better understand cancer metastasis. We have been working with Nicola Brown, Jamie Hobbs, Ashley Cadby, and Ingunn Holen on a cancer research UK funded project on breast cancer bone metastases.

Phagocytosis/Endocytosis

Endocytosis and phagocytosis are processes in which biological cells take in particles (e.g. molecules or microbes) by engulfing them with membrane. The membrane deforms to engulf the particle and then pinches off into a vesicle inside the cell. We are interested in the role of actin and other biopolymers in this process. We are currently collaborating with Kathryn Ayscough's lab and Simon Johnston's lab. With Simon Johnston we are particularly interested in the ability of immune cells called macrophages to engulf and kill infectious bugs.
Image of Nucelus Deformation




Top