The Successful Invasion Of Midgut Epithelium Essay

5. Explain why proteases are secreted in an inactive state and describe the means by which proteases are activated in the stomach and small intestine. – The enzymes protease, amylase and lipase, are potent enzymes that are capable of digesting the pancreatic cells- a process called autodigestion. To protect themselves from autodigestion in case the digestive enzymes accidentally get turned on, pancreatic cells produce enzymes in inactive form called zymogens, which are stored in membrane-bound sacks called zymogen granules. Enteropeptidase (also called enterokinase) is an enzyme produced by cells of the duodenum

As evolution evolved, so did the digestive systems of various organisms. From earth worms to the fetal pig, the digestive systems have changed due to genetic and environmental factors for survival. The six organisms that we dissected in this course are the following: the earthworm, the clam, the crawfish, the starfish, the perch, and the fetal pig. We will discuss each organism’s digestive system associated with their eating habits, discuss the changes in the digestive systems from the more primitive to the more advanced, and discuss how these advanced characteristics improved the efficiency of the organism’s digestive system.

Once N. meningitidis has encountered a healthy host it uses its type IV pilus to protrude from the capsule and bind epithelial cells and erythrocytes within the mucosal surface. The pili also generate what is known as a twitch motility which allows the bacterium to pass the epithelial layer and invade the host.

Chapter 9: Gastrointestinal System The gastrointestinal system is essentially a long tube running from the mouth to the anus. It serves as the primary source nutrients to the body as it breaks down and digest all of the food consumed by the body before excreting it. The gastrointestinal system contains the mouth, teeth, esophagus, slower esophageal sphincter, stomach, pyloric sphincter, small intestine, ileocecal valve, appendix, large intestine, rectum, and anus.

There are several virulence factors associated with the initial infection, including: filamentous hemagglutinin (FHA) and the pertussis toxin. Bordetella pertussis colonizes in the host via filamentous hemagglutinin (FHA) and the pertussis toxin. FHA is a large protein that forms filamentous structures on the cell surface and also binds to galactose residues on the surface of the trachea’s ciliated epithelial cells. The pertussis toxin is a protein that has five subunits: S1, S2, S3, S4, and S5, is also involved in adherence to the tracheal epithelium. Many of these components are also known as adhesions, which bind the bacteria to the host cell. While others utilize different receptors and bind to a glycolipid found specifically on the tracheal epithelium. Bordetella pertussis also produces its own toxins, such as invasive adenylate cyclase, which is a single polypeptide that enters epithelial cells, locally reduces phagocytic activity, and lyses red blood cells, and initiates infection. Lethal toxin, formerly called dermonecrotic toxin, is a protein that causes inflammation where Bordetella pertussis colonizes. Tracheal toxin, a peptidoglycan fragment, destroys ciliated cells, stimulates the release of interleukin-1, and causes fever. Once infected, the individual receives antibiotics, usually erythromycin. In order to have more control of this disease, there needs

Y. pestis has multiple virulence factors which is activated upon entering into the mammalian host (resulting in a change of temperature from lower temperature to around 37°C). For invasion, it has a protease called the plasminogen activator (Pla) that breaks down fibrin. This allows it to spread systemically from the original inoculation site (area of flea bite). This bacterium also has a hemin storage system, which enables it to survive in phagocytic cells and enhances uptake into eukaryotic (host’s) cells. Y. pestis also encode a type 3 secretion system (T3SS), which is a secretion system made up of macromolecular structures that lines the inner and outer membranes of the bacteria. It enables the direct translocation, from bacterial cytosol into host cells, of

The overall structure of NoV Pro is that of a cysteine protease with a chymotrypsin-like fold and a catalytic triad consisting of His-30, Glu-54, and Cys-139 (71). The structures of Norovirus proteases share a high degree of structural similarity to picornaviral 3C proteases (75, 76), making picornaviral proteases an excellent model for comparison. The mechanism of catalysis for the Norovirus proteases is similar to the serine proteases that contain a Ser-His-Asp triad in the active site. The mechanism of catalysis of serine proteases is shown in Figure 2. The catalysis reaction occurs in two halves, acylation and deacylation. First, the carbonyl of the peptide substrate is attacked by the Serine and His residues of the catalytic triad (77). The result is the first of two tetrahedral intermediates which collapses to form the acylenzyme intermediate (77). The second half of the reaction is very similar where a water molecule and His residue attack the acylenzyme intermediate to yield the second “transition-state” intermediate which collapses to release the carboxylic acid product (77). Similar to the serine proteases, the Cys-139 residue of Norovirus proteases functions similarly to the Ser residue and the Glu-54 functions as the Asp residue of the serine proteases while the His residue function is

During a blood meal, microfilariae get ingested by the blackfly. In the surrounding subcutaneous tissues, the saliva of fly acts as a chemo-attractant that attracts the microfilariae. The migration of microfilariae from the midgut of blackfly through the hemocoel to the fly flight muscles occurs after ingestion.

Orientia Tsutsugamushi is a Gram negative bacterium, and this microorganism is an obligate intracellular pathogen. Orientia Tsutsugamushi can cause scrub typhus disease. The microorganisms rapidly abscond from the pathway inside of the body, and then copies in the cytosol of eukaryotic host cells after entry into host cells (Ko). Orientia Tsutsugamushi has developed to block autophagy microbicide defense by escape autophagy recognition. It activates the autophagy way at the early stage of infection. According to Mizushima, “autophagy is an evolutionarily conserved and regulated intracellular catabolic mechanism that mediates the degradation of cytosolic components, including protein complexes and damaged organelles, in a lysosome-dependent

Cytotoxin associated gene A contains a stored pattern at the C- terminus known as the conserved repeat responsible for phosphorylation independent activity (CRPIA) [34]. This motif interacts with β-catenin-E-cadherin complex [35-37], hepatocyte growth factor receptor (MET)[38, 39], phospholipase C gamma (PLC-γ)[40], and partitioning-defective 1b/microtubule affinity-regulating kinase 2 (PAR1b/MARK2) [41-43] [44, 45] It has also been associated with JAK/STAT3 [31]. These interactions lead to cellular responses that promote inflammation, uncontrolled replication, disruption of neighboring cells communication, loss of cell function, loss of cell shape and loss of cell structure [34]. Unphospoporylated Cytotoxin associated gene A also affects zonula occludens 1 (ZO-1) which are proteins essential for epithelial tight junction by dislocating it from its cellular location [46] [47]. It also interrupts the junctional adhesion molecule A (JAM-A), producing dysfunctional construction of cell junctions [48].A variety of studies suggest that Cytotoxin associated gene A interact with PAR1b/MARK2, a crucial regulator of cell function and structure. Cytotoxin associated gene A disrupts its activity by affecting the alignment of microtubule arrangement, in this way causing a loss of cell polarity [49] [22] [47]. PAR1b binds to the CM or CagA multimerization of CagA that is involve in the CagA dimerization [50]

After entry, the bacteria are trapped in a single membrane vacuole known as the phagosome. Lm must escape from the phagosome into the cytosol by the action of the secreted pore-forming toxin, Listeriolysin O (LLO) which is encoded by hly (Portnoy et al., 2002). Getting access to the cytosol is necessary for a successful infection and failure to escape from the phagosome results in the elimination of the bacteria from tissues (Le Monnier et al., 2007). LLO belongs to a family of cholesterol- dependent cytolysins (CDCs) which are secreted as a soluble monomers and characterized by their ability to bind to the cholesterol of host membranes, oligomerize, and form a large pores (Schnupf et al., 2007). Bacterial membranes lacking sterols are therefore not affected by the action of these toxins.

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contains the necessary amino acids required for the parasite to live as well as replicate

N. gonorrhoeae are non-motile and possess type IV pili to adhere to surfaces. The type IV pili operate mechanistically similar to a grappling hook. Pili extend and attach to a substrate that signals the pilus to retract, dragging the cell

Endosymbiosis is the theory that eukaryotic cells were formed when a prokaryotic cell ingested some aerobic bacteria. The first step of the evolution of a eukaryotic cell is the infolding of the cellular membrane. This process takes place when the plasma membrane folds inwards and develops an envelope around a smaller prokaryotic cell. Once the smaller cell is engulfed, it becomes dependent upon its host cell. It relies on the host cell for organic molecules and inorganic compounds. However, the host cell also benefits because it has an increased output of ATP for cellular activities and becomes more productive. This ATP comes from the mitochondrion (the aerobe) that is engulfed.