National Repository of Grey Literature 102 records found  beginprevious55 - 64nextend  jump to record: Search took 0.00 seconds. 
Oxidative stress in bacteria - with an emphasis on the model organism of Escherichia coli
Moravcová, Andrea ; Lichá, Irena (advisor) ; Čáp, Michal (referee)
Most bacterial species encounter aerobic conditions during their life, which can be toxic. This leads to a state of oxidative stress. Toxicity of aerobic environment results from the chemical properties of molecular oxygen and its reactive species (ROS). Bacteria had to adapt to these conditions in the past to ensure preservation and prosperity. This thesis is preferably focused on oxidative stress adaptations in the most elaborated bacterial model - Escherichia coli. Regulation of adaptations at the regulation of transcription, translation and metabolism level are described with emphasis on molecular mechanisms. The main adaptation mechanism against oxidative stress is the deactivation of ROS, as well as the repair of damaged cell structures (macromolecules). These enzyme activities are regulated by several transcriptional regulators. The transcriptional regulators OxyR and SoxRS have been well studied in E. coli. Even though these regulators are conserved across the bacterial spectrum, they may not have the same function in all organisms. For this reason, also other, more or less studied bacterial species - Bacillus subtilis, Streptomyces coelicolor, Pseudomonas putida, Pseudomonas aeruginosa - were included in this thesis. The various strategies of how these bacteria use not only OxyR and SoxRS...
The use of animal models in the study of pathogenesis of Bordetella pertussis
Traganová, Veronika ; Holubová, Jana (advisor) ; Lichá, Irena (referee)
Bordetella pertussis is a strictly human pathogen and a causative agent of whooping cough. The study of bacterial transmission, virulence factors and vaccine efficacy testing became a very relevant topic, due to the disease resurgence in well-vaccinated populations during the past decades. Detailed investigation of bacterial interactions in vivo requires a suitable animal model. The most common used animal for B. pertussis testing is a laboratory mouse, however mice are unable to develop the typical B. pertussis infection symptomps. In the field of vaccine research and testing, the newborn pig has also proved to be a suitable model. By far the best nonhuman host of B. pertussis is the recently discovered baboon model which can perfectly imitate the human respiratory tract conditions, immune response and also the host-to-host transmission. This thesis summarizes basic knowledge of model organisms used in the past and in the present for the study of B. pertussis. At the same time, it shows the comparison of the advantages and disadvantages of the discussed animal models.
Metabolic control of bacterial division.
Valtová, Aneta ; Lichá, Irena (advisor) ; Fišer, Radovan (referee)
Metabolic control of cell cycle has been study for a long time, but it is not completely known. Mechanisms of metabolic control described for a several decade has been explained on molecular level with using a modern methods. Regulation of cell cycle in consideration of metabolism and nutritional status is going on at the several level of cell replication. The most known is about assembly of bacterial cell divisiome. Changes in nutrient availability induce stress response that use low-molecular substances in signaling pathways leading to changes in the cell cycle. One of the most studied is (p)ppGpp that participates in stringent response and affect sigma factors, directly inhibits the initiation of replication by binding to the DnaG primase and indirectly inhibits the elongation of replication. Current researches has revealed that some enzymes with already known enzymatic function in the major metabolic pathways (glycolysis or TCA) also has a function as sensors that transmit the nutritional change signal directly into the cell dividing process. These signals most often inhibits FtsZ protein or affect its helper proteins and subsequent ring formation. Analogues of these enzymes were found in gram-positive (Bacillus subtilis) and gram-negative bacteria (Escherichia coli, Caulobacter crescentus)....
General stress response in Staphylococcus aureus and its role in adaptation to hyperosmotic stress
Kotková, Hana ; Lichá, Irena (advisor) ; Seydlová, Gabriela (referee)
Hyperosmotic stress induces a stress reponse in a halotolerant bacteria Staphylococcus aureus that helps it to survive even the osmotic conditions that are inhibiting for most of the bacteria. Stress responses of S. aureus include a general stress response that activates rapidly on a wide range of stresses and is ensured by expression of genes induced by an alternative sigma B subunit of RNA polymerase (SigB), and more specific responses to hyperosmotic stress associated with transporters of potassium and transporters of compatible solutes. Also, some virulence factors (such as the adhesive Ebh protein) allow S. aureus to survive hyperosmotic stress within the host, thereby helping to colonize it. It is currently known that the general stress response directly and indirectly participates in the specific stress adaptation through the Kdp transport system for potassium (Kdp transporter) and transporters of compatible solutes (PutP and OpuD). Expression of the Kdp transporter and the large S. aureus Ebh protein is SigB dependent, via Agr or ArlRS virulence regulator systems. The formation of a biofilm, in which SigB is significantly involved, may also enable to colonize host niches with low water activity. Hyperosmotic stress by triggering SigB initiates a complex response that is associated not only...
The role of alternative sigma factors of RNA polymerase in regulation of gene expression in Corynebacterium glutamicum
Šilar, Radoslav ; Nešvera, Jan (advisor) ; Branny, Pavel (referee) ; Lichá, Irena (referee)
Abstract Regulation of transcription by extracytoplasmic-function (ECF) sigma factors of RNA polymerase is an efficient way of cell adaptation to diverse environmental stresses. Amino acid-producing gram-positive bacterium Corynebacterium glutamicum codes for seven sigma factors: the primary sigma factor SigA, the primary-like sigma factor SigB and five ECF stress- responsive sigma factors (SigC, SigD, SigE, SigH and SigM). The sigH gene encoding SigH sigma factor is located in a gene cluster together with the rshA gene, encoding the anti-sigma factor of SigH. Anti-sigma factors bind to their cognate sigma factors and inhibit their transcriptional activity. Under the stress conditions the binding is released allowing the sigma factors to bind to the RNAP core enzyme. In this thesis, regulation of expression of genes encoding the most important ECF sigma factor SigH and its anti-sigma factor RshA as well as genes belonging to the SigH-regulon were mainly studied. The transcriptional analysis of the sigH-rshA operon revealed four housekeeping promoters of the sigH gene and one SigH-dependent promoter of the rshA gene. For testing the role of the complex SigH-RshA in gene expression, the C. glutamicum ΔrshA strain was used for genome-wide transcription profiling with DNA Microarrays technique under...
Regulation of expression of Ms1, a sRNA from Mycobacterium smegmatis
Páleníková, Petra ; Krásný, Libor (advisor) ; Lichá, Irena (referee)
Bacteria are exposed to various environmental conditions during their growth. They have to cope with rapid changes in temperature, lack of nutrition, etc. To survive, bacteria alter their gene expression. One type of regulation of gene expression is regulation by small RNAs (sRNAs). In bacteria, a well-studied sRNA is 6S RNA that binds to the RNA polymerase holoenzyme. However, 6S RNA has not been identified in several bacterial species. Mycobacteria are a genus that probably does not have 6S RNA. Instead, Mycobacterium smegmatis possess another sRNA - Ms1. Ms1 structurally resembles 6S RNA and indeed it was first identified as a 6S RNA structural homologue. However, Ms1 binds to RNAP devoid of any sigma factor, and, therefore, is significantly distinct from 6S RNA. This work describes regulation of expression of Ms1. DNA fragments of different length from the region upstream of the Ms1 gene were prepared. These fragments were fused to the lacZ reporter gene and their activity was tested in different growth phases and under stress. This allowed identification and characterization of the core promoter sequence and regulatory sequences that might interact with transcription factor(s). Promoter activity increased with increased length of the promoter fragment and after transition into stationary...

National Repository of Grey Literature : 102 records found   beginprevious55 - 64nextend  jump to record:
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