S. carpocapsae and X. nematophila are mutualistic symbionts that parasitize, kill and use insects for reproduction. S. carpocapsae develop into non-feeding infective juveniles (IJ’s). The S. c. IJ’s serve as vectors for the X. n. The vector IJ’s then colonize at a place termed the vesicle. X. n. are released from the vesicle, via nematode defecation, into a new insect host. This process serves as a model to understand general aspects of horizontal transmission of symbionts by their hosts. It takes very few X. n. cells that are retained in the intestinal vesicle to initiate colonization of S. c.
Microbial attachment to host tissues plays an important role in the initiation of pathogenic and nonpathogenic microbe-host interactions. Besides providing a basis for hosts, specific interaction between bacterial and host molecules is important in determining the ability of some bacterial species to colonize certain hosts, but not others.
Fimbriae, nonfimbrial adhesins and polysaccharides are the general classes of bacterial outer surface structures that mediate adherence to host tissue receptors. Many of the biochemical activities for these processes still remain unknown.
A study of the morphology of the intestinal vesicle was done using differential interference contrast (DIC) light microscopy and transmission electron microscopy. The study concluded that the vesicle is a modification of the anterior nematode intestine and forms independently of bacterial colonization.
The nematode Steinernema carpocapsae and bacteria Xenorhabdus nematophila were studied in this paper. Their symbiotic relationship is formed when X. nematophila bacteria adhere to a site consisting of spherical bodies in the lumen of the nematode’s inte...
... middle of paper ...
...
The effects of this symbiotic relationship could be exploited in the real world. It provides a viable alternative to the use of insecticides. The discharged bacteria consume insects, eliminating their ability to impede the normal growth of crops. This method has been shown to be quite effective. Also it is favored over traditional chemicals as the use of nematodes and bacteria poses virtually no risk to consumers.
Applications to medicine:
Two important compounds have been isolated from Xenorhabdus: nematophin and xenorxide. Nematophin is an antifungal and antibacterial agent. Xenorxide has been shown to attack cancer cells, found in the lungs, breasts, prostate, and colon, and to leave healthy cells alone. The major advantage of these chemicals is that they may be used to combat strains of bacteria that have become resistance to conventional antibiotics.
S. flexneri causes infection via bacterial penetration of the mucous membrane in the human colon. Humans are the only known reservoir to this pathogen (7). Following invasion of M cells and upon contact with the epithelial cells of the colon, S. flexneri releases Ipa proteins through a type three secretion system. Once inside the host cell, Ipa proteins activate small GTPases in the Rho family as well as c-src, a protooncogene, leading to cytoskeletal rearrangements. This alteration to the cytoskeleton allows the bacteria to be macropinocytosed by the host cell. Once inside the host, the pathogen colonizes the cytoplasm. IcsA, a bacterial surface protein, activates the host protein N-WASP and, in turn, stimulates actin assembly by host Arp 2/3. Thus, S. flexneri develops actin-based motility enabling the pathogen to become efficient at cell-to-cell spread and host cell cytoplasmic colonization. Infected cells become highly proinflammatory and secrete IL-8. IL-8 attracts neutrophils to the site of infection. The influx of neutrophils, chemokines and cytokines to the area damages the epithelial layer permeability and, in turn, advocates further S. flexneri invasion (6). Once initial invasion of S. flexneri occurs, the targeted epithelial cells require 45 minutes to 4 hours to mount an inflammatory response (8).
Unlike other worms these freshwater flatworms are unsegmented. They are acoelomates, meaning that they lack a coelom or a complete gut cavity. Their demonstration of bilateral symmetry has been linked directly to cephaliza...
Tapeworms are one of the most common parasites. These parasites hide within the intestinal track of its host and leech off of its nutrients. These parasites cause the infection taeniasis (Parasites – Taeniasis). Although this parasite causes little to no symptoms, they can also cause cysticercosis (Parasites – Taeniasis). This disease infects the muscles, brain, and t...
(ii) Motility and chemotaxis. In addition to their role in the attachment of microorganisms to plant roots, functional flagella are important for bacterial motility. The crucial role of motility for successful rhizosphere colonization is somewhat controversial because some studies have indicated that motility of Pseudomonas is not required for root colonization in wheat and soybean (Howie et al. 1987). However, flagella were shown to be essential for colonization of potato roots (de Weger et al. 1987). Studies confirming the role of motility in the colonization process were performed in the absence of percolating water, and it was assumed that motile or non-motile introduced bacterial strains were transported by the growing roots. However, under more natural conditions the presence of percolating water will affect the dispersal of bacterial strains regardless of their ability to swim.
There are two different types of worms or parasites that can affect animals, in relation to this report the focus will be on parasites that affect sheep. They are called endoparasites and ectoparasites. This report will predominately emphasise on the endoparasites, or the internal parasites. These endoparasites are divided into three categories; nematodes [or roundworms], cestodes, [or tapeworms] and trematodes [or flukes]. The parasites are broken into these groupings due to their structure.
Multiplication of attached organisms leads to confluent growth and biofilm formation. Adherent bacteria synthesise extracellular polymers.
C. immitis is found preferentially in alkaline sandy clay soils in warm dry climates with a high salt content between 10-30cm below the surface.(4, 5) It’s distribution through the soil is patchy, concentrated around animal burrows or soils rich in nitrogen containing animal excreta, persisting for extended periods in the environment.(5)
Many aphid species are partners in mutualistic relationships with several ant taxa (Flatt and Weisser 2000). The degree of this mutualism can be either obligate or facultative depending on several ecological and physiological factors (Stadler and Dixon 2005). Aphids produce nourishing, sugar-rich honeydew which ants can procure by stroking the aphids’ anus or nectar organ with their antennae (Yao and Akimoto 2001). In return, ants offer the aphids protection from predators and parasitoids (Yao and Akimoto 2001). Ants also can perform hygienic services for the aphid colony by removing exuviae and excrement which decreases the risk of fungal growth (Detrain et al. 2010). Honeydew-collecting ants involved in these interactions include the subfamilies Formicinae and Dolichoderinae, as well as several species in the Myrmica and Tetramorium genera of the Myrmicinae subfamily (Stadler and Dixon 2005).
Conventional farming practices are responsible for many negative health and environmental issues. One of the main issues is the creation of monocultures in the farming environment. Specifically growing the same species of plants or animals in mass quantities without variation every season is not natural. Monocultures do not exist in nature (Pollan 67). Nature practices diversity and for good reason. In nature and organic farming, if there is a threat to one species, there are others to balance the decrease in the threatened species. Conventional farmers and the modern food industry argue that planting the same crop year after year is convenient and profitable because it cuts down on the different types of farm equipment necessary in production, and initially, in the types of pesticides, herbicides, and fertilizers needed. However, in this unnatural environment, tremendous amounts of pest...
Microbes are everywhere in the biosphere, and their presence invariably affects the environment in which they grow. The effects
Biofilms are formed by a six step process. First is a reversible process, when an organic monolayer(made of polysaccharides or glycoproteins) absorbs to the surface, altering the chemical and physical properties of the surface. This makes the surface more conditioned and increase the chance that planktonic bacteria will attach. Secondly, also a reversible step, is when the free-floating or planktonic bacteria encounter the conditioned surface, and some attachment of the bacteria may occur. The third step is when the bacteria is left attached too long, then an irreversible attachment occurs. F...
As time has progressed, there has always been an overarching need for high amounts of crop production throughout the world. With the rapid rate of population growth, the need for crops and other sources of nutrients is only increasing. In order to meet these high demands and increase yields, farmers and other agriculturalists have started implementing the use of pesticides. These chemical mixtures are being used in order to prevent, destroy, repel or mitigate any pests from destroying growing crops. However, using pesticides on crops can create massive amounts of pollution, negatively affect an individual’s health, and can spark biodiversity loss within an ecosystem. According to Michael C.R. Alavanja, “Over 1 billion pounds of pesticides are used within the United States (US) each year and approximately 5.6 billion pounds are used worldwide”. With all this in mind, it is clear that pesticides should not be made available to farmers and agriculturalists, and should
Instead of using pesticides in farming a better alternative would be biological control. This is when a natural predator is released into the crop growing area as a result the number of pests can be reduced.
Studies have shown that there are bacteria and fungi with certain strains that live in soil. When they are applied to the seeds, they can aid crops by invigorating plant growth or by decreasing the damage created from plant pathogens bred from the soil. Another example is the bacterial species, Mycorrhiza. It is a fungus, which is able to form a union with a majority of land plants. When this action occurs, that symbiotic relationship assists to increase uptake by the root system to about 90 percent. This in turn helps the plant take in water and nutrients from deep inside the soil. It also allows the activation of genes and physiological changes in the plant which helps them to survive drought circumstances. Other microbes are also able to lift a plant 's resistance to bugs. A larger focus on microorganisms colonizing our plants and sharing a symbiotic relationship with them would greatly improve yields and lessen the need for costly fertilizers and pesticides. Information such as this would be very useful for students in college who are interested in businesses such as