Browsing by Subject "cells"

Now showing 1 - 3 of 3
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    Counting Photobleach Steps and the Dynamics of Bacterial Predators
    (Office of the Vice Chancellor for Research, 2016-04-08) Jashnsaz, Hossein; Tsekouras, Konstantinos; Al Juboori, Mohammed; Weistuch, Corey; Miller, Nick; Nguyen, Tyler; McCoy, Bryan; Perkins, Stephanie; Anderson, Gregory; Presse, Steve
    Photobleach (PB) counting is used to enumerate proteins by monitoring how the light intensity in some regions decreases by quanta as individual fluorophores photobleach. While it is straightforward in theory, PB counting is often difficult because fluorescence traces are noisy. In this work, we quantify the sources of noise that arise during photobleach counting to construct a principled likelihood function of observing the data given a model. Noise in the signal could arise from background fluorescence, variable fluorophore emission, and fluorophore blinking. In addition, in a completely different direction, we explore the role of hydrodynamic interactions on the dynamics of bacterial predators. Our study shows that Bdellovibrio (BV) - a model predatory bacterium - is susceptible to self-generated hydrodynamic forces. Near surfaces and defects, these hydrodynamic interactions co-localize BV with its prey, and this may enhance BV’s hunting efficiency.
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    Identifying Potential Proteasomal assembly factors and/or binding proteins using the yeast Saccharomyces cerevisiae as a model organism
    (Office of the Vice Chancellor for Research, 2015-04-17) Lindsay, Nicole; Hammack, Lindsay; Kusmiercyzk, Andrew
    The proteasome is a large multi-protein complex responsible for the ultimate degradation of proteins in the cell. Damaged or misfolded proteins are targeted for destruction and broken down into peptides. Proteasomal degradation plays a vital role in almost every cellular process, from the cell cycle, to cell development, to apoptosis. Moreover, understanding and identifying the proteasome assembly process, important binding factors, and chaperones that assist in proteasome assembly would be pivotal in developing strategies to remedy cellular disorders caused by defects in proteasomal function. The eukaryotic proteasome is composed of two main sub-complexes, a 20S core particle and a 19S regulatory particle that caps one or both ends of the 20S core particle. The 20S core particle is the degradation component of the proteasome, and it is made up of 14 unique subunits with seven distinct α and β subunits that assemble into four stacked heteroheptameric rings. On the β7 subunit, there is a C-terminal peptide tail that connects two halves of the 20S core particle. Previous research has shown that deletion of the β7 tail slows down proteasome assembly. We generated a yeast strain containing a deletion of the β7 tail along with deletion of two assembly factors, Pba1p and Ump1p. This strain is severely temperature sensitive and will be used to screen a plasmid-borne yeast genomic library. The goal is to potentially identify new proteasomal chaperones and/or binding partners which, when present in high copy, can overcome the defect imposed by the triple mutant.
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    A novel in vitro stretch device for simulating in vivo conditions
    (2018-05) Akella, Arun; El-Mounayri, Hazim
    Biological cells are constantly subjected to mechanical forces such as tension, compression and shear. The importance of these forces in mediating cell signals, maintenance of lineages, promoting embryonic cell differentiation and tissue engineering is only now coming into focus. It has been shown that stretch stimulus can influence growth, differentiation, as well as tissue strength and integrity. Most stretch systems built to understand more of these phenomena suffer from shortcomings, as accurately replicating the in vivo environment is quite challenging. Many of the devices currently available are very expensive as well as limited to a single application. The objective of this thesis is to design, manufacture, test, and validate a novel uniaxial cyclic cell stretch device that overcomes most of the major limitations of existing systems, and to experimentally demostrate that uniaxial cyclic stretch causes a shift towards in vivo characteristics of smooth muscle cells. The stretch mechanism is driven by a single servo motor which makes its operation simple and straight forward. Coolworks Lite, a proprietary software of the servo motor supplier, is used to control the motor and LabVIEW is used to obtain feedback from the sensors. Validation for the stretch machine was done by evaluating the performance of the device against engineering requirements. Methods were suggested to improve shortcomings that were encountered. Also, the machine's unique design allows its extension to a biaxial stretch unit while keeping the same driver platform, a concept for which has been discussed and illustrated.