Bulletin of the American Physical Society
Mid-Atlantic Section Meeting 2021
Volume 66, Number 18
Friday–Sunday, December 3–5, 2021; Rutgers University, New Brunswick, New Jersey
Session C04: Biophysics I |
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Chair: Anirvan Sengupta, Rutgers University Room: 202B |
Saturday, December 4, 2021 9:00AM - 9:36AM |
C04.00001: Cell polarity and shape sensing: how does a cell know its own shape? Invited Speaker: Brian Camley Crawling eukaryotic cells are soft matter driven out of equilibrium by active forces - a great playground for physicists - but their physics also strongly constrains cell function. I will discuss the group's recent work on how reactions on the cell's surface - a model of cell polarity driven by the patterning of Rho GTPase proteins - can become sensitive to cell shape. This shape sensing can lead to surprising new behaviors, like migrating cells developing a spontaneous circular motion. This complex chemical reaction can, in some limits, be understood as minimizing a simple energy proportional to the perimeter of the protein domain on the cell membrane. I will also discuss how roughness in membrane shape can potentially distort shape sensing by leading to protein domains becoming trapped in local minima. [Preview Abstract] |
Saturday, December 4, 2021 9:36AM - 10:12AM |
C04.00002: Cellular memory in bacteria and its influence on future generations Invited Speaker: Hanna Salman We study how the cellular memory influences cellular properties and restrict heterogeneity in future generations. Heterogeneity in physical and functional characteristics of cells proliferates within a population due to stochasticity in intracellular biochemical processes and in the distribution of resources during divisions. It is limited, however, in part by the inheritance of cellular components between consecutive generations. In this talk I will present our new study in which, we characterize the dynamics of (non-genetic) inheritance in the simple bacterial model organism E. coli, and reveal how it contributes to regulating the various cellular properties (size, growth rate, etc.) in future generations. This is achieved using a novel microfluidic device that enables us to measure how two sister cells become different from each other over time. Our measurements provide the inheritance dynamics of different cellular properties, and the ‘inertia’ of cells to maintain these properties along time, i.e. cellular memory. We find that cellular memory is property specific and can last up to ∼10 generations. Our results can uncover mechanisms of non-genetic inheritance in bacteria and help develop quantitative description of cell progression and variation over time. [Preview Abstract] |
Saturday, December 4, 2021 10:12AM - 10:24AM |
C04.00003: A PDE Model For Protocell Evolution And The Origin Of Chromosomes Via Multilevel Selection Daniel Cooney, Fernando Rossine, Dylan Morris, Simon Levin The origin of chromosomes was a major transition in the evolution of complex cellular lie. In this talk, we model the origin of chromosomes by considering a simple protocell composed of two types of genes: a ``fast gene'' with an advantage for gene-level self-replication and a ``slow gene'' that replicates more slowly at the gene level, but which confers an advantage for protocell-level reproduction. Using a PDE to describe how the composition of genes within protocells evolves over time under within-cell and between-cell competition, we find that the gene-level advantage of fast replicators casts a long shadow on the multilevel dynamics of protocell evolution: no level of between-protocell competition can produce coexistence of the fast and slow replicators when the two genes are equally needed for protocell-level reproduction. By introducing a ``dimer replicator'', a linked pair of the slow and fast genes, we see that coexistence between the two genes can be promoted in multilevel competition between fast, slow, and dimer replicators. Our results suggest that genetic linkage can work in concert with deterministic multilevel selection to faciliate coexistence of two genes that are complementary at the protocell level but compete at the level of individual gene-level replication. [Preview Abstract] |
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