#### Presentation Title

Binary vs Polar Division in Chlamydia Trachomatis: Imaging Bias and Computational Model

#### Faculty Mentor

German Enciso

#### Start Date

17-11-2018 12:30 PM

#### End Date

17-11-2018 2:30 PM

#### Location

CREVELING 30

#### Session

POSTER 2

#### Type of Presentation

Poster

#### Subject Area

physical_mathematical_sciences

#### Abstract

Recent work has been made to determine the reproductive mechanism in Chlamydia— a major sexually transmitted disease. Using different experimental evidence, two groups have reached conflicting conclusions as to whether it divides in a binary fashion, or via polar division through bud formation. We use computational methods to study the bias resulting from measuring cell sizes using 2D slices rather than 3D volumes of the bacteria. We find that this bias can lead to a conclusion of polar division, even when division is binary. Additionally, we implement a recent hypothesis of cell fate regulation through cell size, to demonstrate that experimental data is consistent with binary division.

#### Summary of research results to be presented

We simulate imaging of binary division using a geometric approach. We use two spheres with varying distances as our progeny cells and intersect with a uniformly distributed plane to simulate imaging at random orientations. The resulting plane intersections are circle segments in the plane. We compute the areas of these circle segments and collect them in histograms. By first fixing the size of daughter cells, we find that over half of our data is that of asymmetric daughter/parent size ratios. This suggests that most of the images observed using 2D slices would appear to depict polar division, rather than binary. Then we normally distribute the cell sizes in simulation to more accurately depict the biological system; hence we can compare the input and output size ratios. We find that 2D imaging output produces significantly more images of asymmetric division than that of our input. This suggests that an observer using a 2D imaging approach would see cells undergoing polar division rather than binary. Thus, two-dimensional imaging can lead to researchers making incorrect conclusions about cellular division mechanisms. We demonstrate, using deterministic modeling, how these two mechanisms predict radically different behavior of Chlamydia trachomatis in the mammalian cell. Assuming the proposed size control mechanism of conversion between reticulate (RB) and elementary (EB) bodies, we find that the binary division model predicts experimental data (12 to 40 hours post infections) while the polar model does not.

Binary vs Polar Division in Chlamydia Trachomatis: Imaging Bias and Computational Model

CREVELING 30

Recent work has been made to determine the reproductive mechanism in Chlamydia— a major sexually transmitted disease. Using different experimental evidence, two groups have reached conflicting conclusions as to whether it divides in a binary fashion, or via polar division through bud formation. We use computational methods to study the bias resulting from measuring cell sizes using 2D slices rather than 3D volumes of the bacteria. We find that this bias can lead to a conclusion of polar division, even when division is binary. Additionally, we implement a recent hypothesis of cell fate regulation through cell size, to demonstrate that experimental data is consistent with binary division.