Graduation Year

2022

Date of Submission

12-2022

Document Type

Campus Only Senior Thesis

Degree Name

Bachelor of Arts

Department

Physics

Reader 1

Janet Sheung

Reader 2

Adam Landsberg

Abstract

The active nature of cells is fueled by molecular motors which work to transport various cargo. Previous work has shown that cytoskeletal composites reconstituted in vitro facilitate differing modes of cargo diffusion. Active networks of the motor protein myosin and the biopolymers actin and microtubules were shown to transport polystyrene microspheres first subdiffusively then superdiffusively, while inactive networks made without molecular motors transported similar cargo purely subdiffusively. Here, a modified experimental design is investigated in which the speeds of transport for fluorescently labeled DNA, a biologically relevant cargo, in different active and inactive networks in comparison to a control group are analyzed. The active network considered consists of the molecular motor kinesin-1 as well as its associated biopolymer, microtubules and the inactive network is solely microtubules. The transportation of DNA was tracked through these three cytoskeletal networks using fluorescence light sheet microscopy, and the time-dependent flow field of DNA through active cytoskeletal composites were ascertained using PIVlab, a particle image velocimetry module for MATLAB. It was found through statistical pairwise comparisons that DNA in the inactive network was consistently transported the slowest, while DNA in the control group had the highest average speeds. The higher speeds found in active composites in comparison to inactive composites is reflective of the lack of superdiffusive phase in which mean squared displacement of cargo increases at an increasing rate that was found to be characteristic of inactive networks. The hierarchy of average speeds found that place DNA in the inactive network in the slowest position support the findings in previous studies that used inorganic materials such as polystyrene microspheres possibly having relevance to in vivo biological processes such as viral DNA transport in the cell.

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This thesis is restricted to the Claremont Colleges current faculty, students, and staff.

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