Analysis of Stochasticity in Competence Regulation of Streptococcus Mutans Using Microfluidics and Single Cell Analysis

MISSING IMAGE

Material Information

Title:
Analysis of Stochasticity in Competence Regulation of Streptococcus Mutans Using Microfluidics and Single Cell Analysis
Physical Description:
1 online resource (129 p.)
Language:
english
Creator:
Son, Minjun
Publisher:
University of Florida
Place of Publication:
Gainesville, Fla.
Publication Date:

Thesis/Dissertation Information

Degree:
Doctorate ( Ph.D.)
Degree Grantor:
University of Florida
Degree Disciplines:
Physics
Committee Chair:
HAGEN,STEPHEN JAMES
Committee Co-Chair:
HEBARD,ARTHUR F
Committee Members:
MUELLER,GUIDO
MUTTALIB,KHANDKER A
BURNE,ROBERT ARTHUR,JR

Subjects

Subjects / Keywords:
analysis -- bimodal -- bistability -- cell -- competence -- comrs -- comx -- comy -- csp -- fluorescence -- microfluidics -- mutans -- single -- stochasticity -- streptococcus -- xip
Physics -- Dissertations, Academic -- UF
Genre:
Physics thesis, Ph.D.
bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
born-digital   ( sobekcm )
Electronic Thesis or Dissertation

Notes

Abstract:
Streptococcus mutans (S. mutans) is a Gram-positive and anaerobic pathogen commonly found in the human mouth. It is best known for its role as the primary causative agent of dental caries. Like many bacteria, Streptococcus mutans has the ability to import exogenous DNA and alter its own genetic composition through a behavior known as genetic competence. Genetic competence plays an important role in the virulence of S. mutans and is closely linked to its growth rate, biofilm formation, and stress tolerance. Over 30 years of research have revealed several essential genes in the competence regulation of S. mutans. These include comX, which encodes an important regulator for the late competence genes, and comY, an essential late competence gene for the internalization of exogenous DNA. The regulation of both genes involves at least two quorum-sensing signal peptides, CSP and XIP. Regulation of the com genes is also highly stochastic, such that only a fraction of cells in a population become competent. The detailed operation of these circuits and the origin of such stochasticity are not well understood due to the complexity of multiple interacting regulatory circuits and environmental inputs. To study these mechanisms, we used microfluidics to gain precise control over the chemical environment, introduced fluorescent protein reporters of gene expression, and analyzed the fluorescence images to quantify the gene expression in individual cells. Our study of comX revealed that the two signal peptides induce comX expression in different ways, with the growth medium playing an important role in this induction. CSP induced bimodal comX expression in complex (peptide rich) media, while XIP did not induce any comX expression. On the contrary, only XIP was able to induce comX expression in defined (peptide free) media, and the expression pattern was unimodal. It was also shown that cytoplasmic copy of ComS peptide is required for bimodal expression of comX. To further explore the origins of stochasticity in S. mutans genetic competence, we cloned dual color fluorescent reporters (GFP and RFP) to monitor two vital genes (comX and comY) simultaneously at the single-cell level. The study showed evidence that an additional bistable switch or mechanism follows comX activation, upstream of comY. Such series of bimodal or non-linear circuits may allow S. mutans to create a diverse community-wide response in competence gene expression.
General Note:
In the series University of Florida Digital Collections.
General Note:
Includes vita.
Bibliography:
Includes bibliographical references.
Source of Description:
Description based on online resource; title from PDF title page.
Source of Description:
This bibliographic record is available under the Creative Commons CC0 public domain dedication. The University of Florida Libraries, as creator of this bibliographic record, has waived all rights to it worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.
Statement of Responsibility:
by Minjun Son.
Thesis:
Thesis (Ph.D.)--University of Florida, 2014.
Local:
Adviser: HAGEN,STEPHEN JAMES.
Local:
Co-adviser: HEBARD,ARTHUR F.
Electronic Access:
RESTRICTED TO UF STUDENTS, STAFF, FACULTY, AND ON-CAMPUS USE UNTIL 2015-05-31

Record Information

Source Institution:
UFRGP
Rights Management:
Applicable rights reserved.
Classification:
lcc - LD1780 2014
System ID:
UFE0046217:00001