Unit 2 Assignment 1 Cellular Structures and Pathogenicity

Early infection with P. aeruginosa resembles acute non-CF infections within the airways, however the bacterium can evolve genotypically and phenotypically during infection, and adapt to its human host1. Adaptive mutations resulting in loss of motility and acquired antibiotic resistance support a sessile lifestyle that is associated with persistent infection within the CF lungs9, 12. Chronic infection is characterized by immunity-mediated inflammation from increased recruitment of polymorphonuclear leukocytes to the lungs2. Furthermore, P. aeruginosa utilizes an assortment of virulence factors such as proteases, exotoxin A, and phospholipases to destroy host tissue, by which the symptoms of CF patients are

- H. pylori has 4 to 6 "lophotrichous flagella" which are its favor in motility. Usually, the

Bacteria will always want to thrive and do what is best for itself and find the most suitable host. The ideal situation between a host and bacteria would be mutualism which is a form of coevolution in which two species benefit from the same act. Michal Pollen briefly discusses this in Botany of Desires by comparing both bees and flowers. When he puts himself in the mind of the bee he can understand that the plants were luring the bees for there own desires. In other words, the plants get the bee to perform activities that they cannot themselves.

Background: Cystic fibrosis facilitated chronic lung infections caused by Pseudomonas aeruginosa have caused many great tribulations within the healthcare field. As a highly opportunistic bacteria, many treatments fail to fully eradicate the biofilms layers within the thick mucosal membrane, which lines the lungs of CF patients.2 The median life expectancy for CF patients is around 40 years, however those who acquire P. aeruginosa within

The effectiveness of disease treatment is often presented by the challenge of antimicrobial resistance. Cystic Fibrosis (CF) for example, is a pulmonary infection characterized by the poly-microbial growth of bacteria within biofilms, in the pulmonary tract of humans. For children suffering from CF, Staphylococcus aureus (S. aureus) initially colonizes their airways, which with age, becomes replaced by Pseudomonas Aeruginosa (P. aeruginosa). The eradication of P. aeruginosa by antibiotics fails in 10-40% of CF patients. In the article, it was proven that there existed an interaction between the staphylococcal protein A (SpA) from S. aureus filtrates (SaF, a bacterial supernatant of S. aureus), and an exopolysaccharide (Psl) of P. aeruginosa. This interaction lead to the aggregation and increased resistance to tobramycin¬ – an antibiotic used to eradicate P. aeruginosa, to prevent chronic colonization of the bacteria. The study conducted involved 7 samples of P. aeruginosa that were taken from individuals who underwent successful eradication treatment, and 7 samples from individuals who still had persistent isolates. These P. aeruginosa samples were cultured for 24 hours in media. When SaF was added to the overnight preformed biofilms, the eradicated isolates were not affected by the SaF; however, the persistent isolates showed significant reduction is surface coverage due to densely packed cellular aggregation, without affecting the biomass or viability of persistent isolates. The

When antibiotic is used most of the bacteria die but a few bacteria with antibiotic resistance gene survive and reproduce and pass this advantage to their offsprings. This selective pressure exists naturally, however antibiotic misuse can be accused for fastening the spread of the antibiotic resistance gene [Refer to figure 2] (Learn Genetics 2015). Consequently, inappropriate antibiotic intake will lead to a greater chance of superbugs being developed. Antibiotic resistance can be defined as a new ability which a bacterium has developed to stay unattached in the presence of an antibiotic that was previously effective to destroy the bacterium (ABC science 2015). Four key mechanisms that has been identified for bacterial antibiotic resistance can be listed as: producing enzymes that inhibit the functionality of the drug, reducing the effectiveness of the drug by producing targets against which the antibiotic, reducing the permeability of the drug into the bacterium and active export of antibiotics using various pumps (Pogson 2012). All these mechanisms can be developed by any of the bacteria when the corresponding mutated gene of antibacterial resistance is received. The genes code for specific proteins, and variation in the gene leads to alteration of the shape of proteins. This leads to changing the functionality

In addition, many of the drugs available to treat infectious disease actually originate from bacteria and fungi. In Biology, constant inquiry of the mechanisms of life lead to new discoveries every day. Clearly, microbes are very important for studying and understanding our world. Dr. Henkin stressed their importance in the seminar, specifically the study of bacteria and bacteria’s manipulation of gene expression.

Bacterial endospores are highly resistant structures that can withstand many forms of treatments, including heat and UV (Atrih & Foster, 2002), and this characteristic is facilitated by their unique spore structure. Bacterial capsules play an important role in the virulence of bacteria for their host, and enable bacterial cells to evade host defense mechanisms and survive hostile environments. The structure and function of endospores and capsules work specifically to benefit the microbial cell; furthermore, various physiological changes occur in these structures as a result of environmental stress (Sahin, Yong, Driks, & Mahadevan, 2012). The specific mechanism of these physiological changes, the types of environmental stresses that cause the changes, and how these correlate with endospore and capsular structure and function are essential to the understanding of this topic.

Quorum sensing isa form of cell-to-cell communication that bacteria use to coordinate the expression of genes involved in behaviours such as flagellar movement9,10 virulence factor production,11,12 and

In axenic culture, it forms a tear drop-shaped trophozoite, 10 × 7 μm in size [4] (Fig. 1A). T. vaginalis possesses five flagella. Four of these flagella are anterior flagella for twitching motility [1]. The fifth flagellum is attached by the undulating membrane. Its function is associated with quivering motility [4]. The protozoan also owns an axostyl that consists of tubulin and actin fibers [1]. The axostyl is associated with cell attachment and mitosis [4]. During infection, T. vaginalis internalizes the flagella and transforms into an amoeboid appearance in order to attach vaginal epithelial cells [1](Fig. 1B and C). The cytoplasm consists of a single nucleus and hydrogenosomes. The hydrogensomes are energy-producing organelles

Dr. Zemer Gitai received his bachelor’s degree from the MIT, and after this he completed his graduate endeavors from the UCSF. During this time, he concentrated in working on axon guidance in Caeorhabditis elegalns because he wanted to find out where the worm’s neurons came from and how they worked. This was the start of his interest in how small molecules such as proteins worked together as a complex system, and how spatial cues were being controlled. Dr. Gitai later joined Princeton University’s faculty and became the Director of Graduate Studies for the Department of Molecular Biology. Now Dr. Gitai focuses on the cell biology of bacteria and how their cells are able to self-organize across spatial scales.

1984). Large majority of bacteria move towards or away from stimuli using chemokinesis. Chemokinesis can be positive meaning towards or negative meaning away from a chemical origin. The type of movement is dependent on the type of flagella present, monotrichous where the rotation is counter clockwise via a running movement or clockwise through a tumble movement. Monotrichous flagella contain only a single flagellum in one pole compared to the peritrichous flagellum is multiple flagella arranged in tufts in polar or random areas (Macnab, R. 1984). This movement occurs also with Peritrichous flagella where the movement occurs in a forward run or a tumble. This movement can be controlled through the mechanism of switching the rotation of flagella towards attractants or away from repellants. Movement towards attractants occurs through decreasing abundance of tumbles and enlargement of the run lengths themselves. The opposite occurs for movements away from with reduction of run lengths and the increased repetitiveness of the tumble

The bacterium evolved by loosing its genes converting it from a free-living microbe into a pathogen. It needs the host’s nutrients in order to survive. The bacterium latches itself onto the host epithelial cells by a 160 kDa type 1 pilli. The pilli, located on a specific organelle on the polar region of the

Bacteria regulate their population gene expression by cell-to-cell communication through a process known as quorum sensing, a ‘collective sensing’ of molecules that are emitted in the environment, leading to a collective response (Popat et al., 2015). Quorum sensing is widely used to control various biological processes for their survival, usually those that are unproductive in an individual cell (Lixa et al., 2015). Depending on the biological process the bacteria regulates, quorum sensing undergoes different mechanisms and tight regulatory circuits to communicate with each other and transmit signals.

Although both Archaeal and bacterial cells possess flagella for motility, the composition of each organism’s flagellum is very different. In bacterial cell, the flagellum is composed of a basal body, external protein filaments both are joined together by a third component called the hook.(Bacteria Flagella David Gene Morgan , Shahid Khan). In Archaeal, the protein filament is polymerised, glycosylated and very much thinner. The Archaeal flagellum is believed to be similar to the bacteria IV pilus in structure.(www.uniprot.org/keywords/974).