Complex Fluids and Flows in Mathematical Biology

Monday, June 14 at 11:30am (PDT)
Monday, June 14 at 07:30pm (BST)
Tuesday, June 15 03:30am (KST)

SMB2021 SMB2021 Follow Monday (Tuesday) during the "MS02" time block.
Note: this minisymposia has multiple sessions. The second session is MS03-MMPB (click here).

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Calina Copos (University of North Carolina at Chapel Hill, USA), Tony Gao (Michigan State University, USA), On Shun Pak (Santa Clara University, USA), Yuan-nan Young (New Jersey Institute of Technology, USA)


Biological fluid environments often display highly complex characteristics due to the presence of microstructure formed by suspensions of passive and/or active components such as proteins, microtubules, or self-propelled particles that interact with a flow. The complexity of these biological fluids and flows poses challenges to the mathematical description of the physics governing the biological processes. Continuing developments of mathematical and numerical tools have enabled the studies of biological processes involving complex fluid environments. This mini-symposium will focus on recent advances in this vibrant field of research. Topics include the impacts of complex rheology and heterogeneity of the fluid environments on various biological processes (e.g., cell motility, mucus transport) as well as novel emergent dynamics of active fluids. Fundamental insights gained from these complex biological flows will improve human understanding of important biological processes, diseases, and thereby the development of new therapies to improve health outcomes.

Calina Copos

(University of North Carolina, Chapel Hill, USA)
"Chimenying movement from the perspective of a cell"
Cell migration is critical for many important physiological processes, such as embryogenesis, tissue repair, and cancer metastasis. In experiments, some cells have been shown to migrate using round membrane protrusions called blebs while confined between two surfaces, such as a gel and a glass coverslip. These cells do not need to adhere to the channel walls in order to migrate under confinement, yet it is unclear how traction forces are coordinated in space and time to generate motion. A dynamic 2D computational model of a blebbing cell in a narrow channel is presented. The model includes the mechanics of the cortical actin and cell membrane, intracellular fluid flow, and evolution equations for the cortical actin for bleb formation and retraction. Several channel models are considered, including two rigid walls and the combination of a rigid and elastic wall. Model outputs include cell velocity, intracellular pressure, and traction forces on the channel walls. The contribution of confinement pressure to total intracellular pressure is quantified, and model simulations show adhesion to the substrate is necessary for migration when the channel is modeled by two rigid walls.

Jorn Dunkel

(Massachusetts Institute of Technology, USA)
"Altruistic fluid transport during fly egg development"
Fluid flow plays an important role during egg cell development. From insects to mice, oocytes mature by acquiring cytoplasm from sister germ cells, yet the biological and physical mechanisms underlying this transport process remain poorly understood. To study the dynamics of “nurse cell dumping” in fruit flies, we combined direct imaging with flow-network modeling and found that the intercellular pattern and time scale of transport are in accordance with a fundamental hydraulic pressure law. Changes in actomyosin contractility are observed only in the second phase of nurse cell dumping as surface waves that drive transport to completion. These results show that tandem physical and biological mechanisms are required for complete and directional cytoplasmic transport into the egg cell. (Imran Alsous et al., PNAS 118: e2019749118, 2021)

Sarah Olson

(Worcester Polytechnic Institute, USA)
"Centrosome movement during mitosis"
Proper formation and maintenance of the mitotic spindle is required for faithful cell division. While much work has been done to understand the roles of the key molecular components of the mitotic spindle, identifying the consequences of force perturbations in the spindle remains a challenge. We develop a computational framework to account for centrosome movement within the cytoplasm and utilize live cell imaging to inform and validate the model. Specifically, we investigate the role of cortical dynein on spindle pole length fluctuations.

Arezoo Ardekani

(Purdue University, USA)
"Swimming near a surfactant laden interface"
The interaction of motile microorganisms and surrounding fluids is of importance in a variety of biological and environmental phenomena including the development of biofilms, colonization of microbes in human and animal bodies, formation of marine algal blooms and bacterial bioremediation. Many microorganisms, especially bacteria, actively search for nutrients via a process called chemotaxis. The physical constraints posed by hydrodynamics in the locomotion of microorganisms can combine with their chemotactic ability to significantly affect functions like colonization of nutrient sources. Motivated by bacterial bio-remediation of hydrocarbons released during oil spills, I will discuss the role of hydrodynamics toward dictating distribution of microbes around interfaces and drops in the presence and absence of surfactant. We find that the presence of the surfactant significantly alters the dynamics of the swimmers specially by affecting their reorientation.

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Virtual conference of the Society for Mathematical Biology, 2021.