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Role of small effector molecules in bacterial signalling.
Kolář, Petr ; Lichá, Irena (advisor) ; Hilská, Markéta (referee)
Small effector molecules play an important role in bacterial physiology. There are many types of them in the bacterial cell. One group are small signalling molecules which participate in quorum sensing, enabling bacterial cell-cell communication as part of a extracellular signalling. These molecules mediate information about the cell density and different qualities of the extracellular matrix. Next group of small effector molecules are modified nucleotides. They participate in intracellular signalling pathways which regulate the switch of bacterial lifestyle according to changing environment. Best studied are signalling pathways using the molecules - c-di-GMP and (p)ppGpp. Detail studies were done in case of gram positive (Bacillus subtilis) and gram negative (Escherichia coli, Vibrio cholerae) bacteria, where was proved the connection between c-di-GMP signalling pathways and quorum sensing (Vibrio cholerae, Xanthomonas campestris). Important discovery in field of small effector molecules is the c-di-AMP signalling pathway in Bacillus subtilis. New regulatory mechanisms were determined in well-known small effector molecule cAMP, regarding the signalling pathways connections (Vibrio cholerae). Recent studies considering the cooperation of the extracellular and intracellular signalization pathways...
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Changes in the ability to form persisters in chronological isolates of Staphylococcus aureus
Kotková, Hana ; Lichá, Irena (advisor) ; Tkadlec, Jan (referee)
In immunodeficient patients, for example with cystic fibrosis (CF), the opportunistic pathogen Staphylococcus aureus causes chronic infections of respiratory tract that are treated with antibiotics (ATB) in the long term. However, exposure to antibiotics can lead to persistence, thereby result a recurrence of infection. The aim of this work was to examine in selected pairs of S. aureus chronological isolates from the respiratory tract of CF patients how their ability to form persisters is changing in time. I have found that the ability to persist within the clonal pair does not change significantly after two years of survival in the host, and that the ability to persist depends on the adaptative mutations of the isolates. Persister formation may depend on mutations in operon of the alternative sigma B factor (sigB) and the major virulence gene regulator (agr). By dual staining with DioC2(3) and To-pro-3, I was able to determine the changes in membrane potential and membrane permeability during the killing curve with ATBs. The distribution into subpopulations according to these parameters depends primarily on the antibiotic used. I conclude that various antibiotics can induce different mechanisms causing a persistent state. Futhermore, I have constructed plasmids with a labeled promoter to determine...
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Changes in the ability to form persisters in chronological isolates of Staphylococcus aureus
Kotková, Hana ; Lichá, Irena (advisor) ; Tkadlec, Jan (referee)
In immunodeficient patients, for example with cystic fibrosis (CF), the opportunistic pathogen Staphylococcus aureus causes chronic infections of respiratory tract that are treated with antibiotics (ATB) in the long term. However, exposure to antibiotics can lead to persistence, thereby result a recurrence of infection. The aim of this work was to examine in selected pairs of S. aureus chronological isolates from the respiratory tract of CF patients how their ability to form persisters is changing in time. I have found that the ability to persist within the clonal pair does not change significantly after two years of survival in the host, and that the ability to persist depends on the adaptative mutations of the isolates. Persister formation may depend on mutations in operon of the alternative sigma B factor (sigB) and the major virulence gene regulator (agr). By dual staining with DioC2(3) and To-pro-3, I was able to determine the changes in membrane potential and membrane permeability during the killing curve with ATBs. The distribution into subpopulations according to these parameters depends primarily on the antibiotic used. I conclude that various antibiotics can induce different mechanisms causing a persistent state. Futhermore, I have constructed plasmids with a labeled promoter to determine...
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Role of small effector molecules in bacterial signalling.
Kolář, Petr ; Lichá, Irena (advisor) ; Hilská, Markéta (referee)
Small effector molecules play an important role in bacterial physiology. There are many types of them in the bacterial cell. One group are small signalling molecules which participate in quorum sensing, enabling bacterial cell-cell communication as part of a extracellular signalling. These molecules mediate information about the cell density and different qualities of the extracellular matrix. Next group of small effector molecules are modified nucleotides. They participate in intracellular signalling pathways which regulate the switch of bacterial lifestyle according to changing environment. Best studied are signalling pathways using the molecules - c-di-GMP and (p)ppGpp. Detail studies were done in case of gram positive (Bacillus subtilis) and gram negative (Escherichia coli, Vibrio cholerae) bacteria, where was proved the connection between c-di-GMP signalling pathways and quorum sensing (Vibrio cholerae, Xanthomonas campestris). Important discovery in field of small effector molecules is the c-di-AMP signalling pathway in Bacillus subtilis. New regulatory mechanisms were determined in well-known small effector molecule cAMP, regarding the signalling pathways connections (Vibrio cholerae). Recent studies considering the cooperation of the extracellular and intracellular signalization pathways...
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