Melittin Lab Report

It has prompted efforts to develop so-called alternatives to the antibiotics. Its benefits may be superior to the prescription antibiotics as it doesn’t cause antibiotic resistance and has no harmful side effects.

Drug therapy relies on the principle of selective toxicity, where the effects of the drug are only harmful towards the foreign parasite and not at all to the host. By comparing the effects of different drugs on various parasitic organisms we are able to distinguish the type of disease or infection that is present as well as the mechanism of action that takes place by each drug in question. The drugs may function by interacting with enzymes such as transpeptidase and thymidylate synthetase, for example Penicillin and 5-FU function respectively. The effectiveness can be quantified by measuring the zones of inhibition created by the drug on the plate of the bacteria or fungus. This is the area where there is no growth due to the action of the drug. The discovery that the Micrococcus-luteus is classed as a bacteria was made apparent due to Penicillin’s success in inhibiting it’s growth. The action of the Amphotericin solely on the Pythium, gives reason to believe that it can be grouped with fungal growths.

A study involving 200 patients showed that 21% developed diarrhea and 50% showed signs of PMC (4). Subsequent studies suggested that enteric bacteria play a role in the development of PMC, such as the finding that vancomycin is protective in hamster guts against clindamycin colitis (5). It appeared that broad-spectrum antibiotics seemed to be altering normal floral microbiota, providing wide-open spaces for the overgrowth of pathogenic organisms to occur.

When examining the D. Melanogaster mutants in the lab, our group immediately noticed an apparent difference from the wild-type flies. None of the mutants were able to fly. This led us to believe that we were dealing with a wing mutation. Upon further examination, we concluded that it was the overall wing shape that prevented the mutants from flying. The wing shapes among the mutants varied in both size and shape. Some were long, while others were short. The mutant wings could be distinguished into two general classes. One division of the mutant wing was short and stubby, almost a fourth the size of the wild-type wing. The rest of the mutants ranged in wing size and length, however many mutant wings were the same length as the wild-type wings. Although the

To date, the following groups of peptides have been identified: tryptophyllins (Ge et al. 2014, Wang et al. 2015), tachykinins (Mignogna et al. 1997, Wang et al. 2008), bradykinins, caerulein, sauvagine (Mignogna et al. 1997, Wang et al. 2008), and opioid peptides (Mignogna et al. 1997). In more recent years, investigators discovered adenoregulin, caerin homologs, dermaseptins (Wang et al. 2008), and medusin (Xi et al. 2013). The primary function of these peptides is to kill pathogenic bacteria, but they inhibit the growth of other parasitic microorganisms as well (Clarke 1997, Wang et al. 2015). To carry out their antimicrobial activity, most peptides interfere with the plasma membrane of the bacterium (Nicolas and Amiche 2006, Rollins-Smith et al. 2005). These peptides are cationic, or positively charged, and attach to the negatively charged heads on the microbe’s phospholipid bilayer (Nicolas and Amiche 2006, Rollins-Smith et al. 2005). Complex steps then occur, but in the end, the orientation of the bacterium’s cell membrane is disturbed, which leads to cell destruction (Nicolas and Amiche 2006, Rollins-Smith et al. 2005). While some scientists researched how these peptides attacked microbes, others investigated and identified new types of peptides in the red-eye leaf frog’s

The intestine contains 70% of the body’s circulating lymphocytes, many of which are found within the epithelium [29]. In the lamina propria there are several lines of immune cells, key to the host response to microbiota, such as macrophages, dendritic cells and myofibroblasts [30,31]. Gut lymphoid tissue, and surface and circulating immunoglobulin concentrations rise substantially with the introduction of bacteria to the gut [32]. In early human life, pioneering species in the gut interact through surface cell receptors on gut immune cells, such as caspase-recruitment-domain protein (CARD), and toll-like receptors (TLRs), to promote the expression of host genes that generate an intraluminal and mucosal environment that further favors their colonization [33,34]. Besides the TLRs there is another family of membrane-bound receptors for detection of proteins called NOD-like receptors, leucine-rich repeat containing‖ proteins (NLRs). NRLs are located in the cytoplasm and are involved in the detection of bacterial pathogen-associated molecular patterns (PAMPs) that enter the mammalian cell. NRLs are especially important in tissues where TLRs are expressed at low levels [35]. In addition to intestinal epithelial cells, the epithelium includes specialized cells such as goblet cells, which secrete the protective mucus layer limiting the contact between bacteria and epithelial cells, and Paneth cells,

Although mucin is an essential component of mucus, little is known about the evolution of mucin genes or other genes associated with the maintenance of mucosal linings, their expression patterns or what specific role mucins and associated genes play in mucosal barrier function and immunity in cnidarians (Schama et al., 2012). As a defence against infectious and external stimuli, the mucosal barrier has evolved to respond to physiological and immunological stimuli originating from diverse organisms and the environment, including ultra-violet radiation, bacteria and desiccation (Linden et al., 2008).

Mannose-binding lectin is an important component of the innate immune system. MBL is originally synthesized in the liver, circulates throughout the body and has the ability to identify a broad range of pathogens based on recognition of carbohydrate repeats displayed on microbial surfaces .

Pathogenic L. monocytogenes go through an intracellular life cycle involving early escape from the phagocytic vacuole, rapid intracytoplasmic multiplication, bacterially induced actin-based motility, and direct spread to neighboring cells, in which they reinitiate the cycle. The bacterium is first phagocytosed by these cells and secretes a pore-forming toxin called listeriolysin, which allows the bacterium to escape from the phagosome. All virulent strains of L. monocytogenes synthesize and secrete listeriolysin. Phospholipase A and B are other virulence factors that facilitate escape of L. monocytogenes from the phagosome. Once out of the phagosome L. monocytogenes is capable of rapid division in the cytoplasm, evading the immune response and moving throughout the cytoplasm from cell to cell. L. monocytogenes is well known for its ability to propel itself like a rocket through the cell cytoplasm. This is the result of the bacterium’s ability to polymerize actin filaments at its tail end. Actin is arranged in subunits to form microfilaments that are capable of directing cell movement. L. monocytogenes accomplishes cell motility through a virulence factor called ActA that takes advantage of normal actin polymerization going on in the cell. The ActA protein shares sequence homology with a protein called WASP that is found in virtually all eukaryotic cells. WASP is responsible for recognizing and

The article also discusses the interesting capabilities of some bacteria. It states that some are able to escape phagocytosis and the process of opsonisation by utilising an external polypeptide layer known as the cell capsule. Similar to viruses, some bacteria are also able to execute Antigenic Variation, and this method of evading microbial detection is only effective

After internalization of C. albicans in phagocytes, it has been observed that the target fungal pathogen like any other microbial pathogen follows the path from phagosomes to phagolysosomes and gets fumigated and killed. During infection, Candida species are exposed to higher levels of reactive oxygen species (ROS), reactive nitrogen species (RNS) and antimicrobial peptides, low pH and reactive chloride species (HOCl) inside macrophages and neutrophils, and survival through these harsh conditions is essential for establishing disease and virulence. C. albicans evolved systems to directly scavenge the ROS produced by host cells and establish systemic infection. C.

Antimicrobial peptides (AMPs) are small proteins with potent antibacterial activity that are found in a variety of organisms, including humans [23]. AMPs can be classified according to their size of length, α or β conformational and predominant amino acid. Table 1.1 shows the different classification of AMPs with examples.Among the four groups of AMPs, the cationic antimicrobial peptides with amphipathic α-helical structure accounts for the most of natural AMPs [25]. The major difference within amphipathic α-helical structure AMPs lays in the sequences despite their common cationic and amphiphilic nature are similar [26]. Cathelicidins and defensins peptides are the two most frequently studied AMPs, these AMPs are positive charged and have the ability to kill microbes. They can function charged residues to separate from hydrophobic resides, associate with negative charged acidic polymers and molecules on the bacterial cell surfaces (Figure 1.5). It can disrupt the cell membrane’s physical integrity by the means of membrane thinning and transient pore formation [27]. Studies show that these AMPs can translocate through the membrane to kill bacteria [28].

The finding was in agreement with the previous results of the mass spectrometry, confocal microscopy of protein interaction reporter marked human cells, and also the immune-nano-gold electron microscopy imaging of additional protein interaction cross-linked cells of bacteria (Navare et al., 763). After the implementation of data processing stages, the researchers found six hundred and ninety distinctive cross-linked peptides making six hundred and twenty-six peptide pairs originating from two hundred and eleven proteins. 70% of these peptides were peptides of a lone protein consisting of non-overlapping and non-identical structures (Navare et al., 763). 8% of the predicted peptides matched the links among peptides of a lone protein possessing identical and overlapping consequences. The remaining 22% represented the cross-linked peptide sets which were among different proteins. Various techniques are available which help in the determination of the cross-linked and non-cleavable peptides (Navare et al., 763). There is the possibility of these approaches to show the improved determination of homodimer peptide sets because these two peptides share the same fragments in multifarious MS2 spectra. However, is not true for cleavable crosslinkers, ReACT and other analogous techniques. ReACT calculates produced cross-linked peptide masses as they produced cross-linked peptide are removed from the

It has been widely used in high risk population, such as the groups with AIDS, diabetes and so

Many antimicrobial peptides can be found in different species but among them a few can be isolated from the human. Among them, two are very much important and they are cathelicidins (LL-37) and defensins (alpha and beta).