Shigella flexneri Shigella flexneri, a facultative anaerobe belonging to the family Enterobacteriaceae, is a Gram-negative rod that is the causative agent of diarrhea and dysentery in humans. Potentially life-threatening, S. flexneri's effects include bacteremia, hemolytic uremic syndrome (HUS) and toxic megacolon (4). The principle disease of diarrhea and dysentery caused by this pathogen is known as shigellosis. 10-100 organisms are sufficient to cause disease, and transmission is generally from person-to-person by way of fecal-oral (2). Shigellosis can be characterized as a disease with over 60% incidence in children ages 1-5 (6). Life cycle: 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). A diagram outlining S. flexneri's type three secretion system can be viewed at: http://www.grad.ucl.ac.uk/comp/2003/jointposter/gallery/index.pht?entryID=29 Virulence: A 214-kb virulence plasmid encodes for S. flexneri's entry into human epithelial cells and intra-intercellular movement (6). Once in contact with the target cell, Ipa proteins (IpaB, IpaC and Ipa D) encode for a specific type III secretion system, thus, enabling entry of the pathogen into the target cell and characterizing S. flexneri with an invasive phenotype (1). One 30-kb block of the plasmid contains genes at the ipa/mxi-spa locus.
Once the recombinant plasmid was obtained, it was then inserted into E. coli cells through transformation. From a successful transformation, we expected the bacterial cells to translate the inserted EGFP sequence into its protein form. The bacteria cultures were plated on petri dishes containing growth supplement, Luria Broth (LB), an antibiotic: Kanamycin, and IPTG which induced the fluorescence property within successfully transformed bacterial colonies. Different variants of the petri dishes were also included as control and unknown.
In this paper, I will discuss what tornadoes are and how they form, what different forms of tornadoes there are, what tornado watches and warning are and give examples of tornadoes in Oklahoma and what destruction they caused, also while providing information about the Doppler radar.
In the end, Janie found herself being defined by other people, so to say Logan, Joe, and Tea Cake. During her marriage to Logan, Janie is viewed as a spoiled and non-hard working girl that needs to learn what it means to make a living. In her marriage to Joe, Janie is only needed for her outward appearance for him to define as his possession; never did he consult her about what she wanted. In both of these relationships she was forced to be something that she was not. Once Tea Cake came along everything had changed; going from following another man’s orders to being able to live a fun-loving life. Throughout the time she spends with him, finally free from being defined by someone else, Janie Crawford discovers who she is and what love is.
Legionella pneumophila GRAPH Introduction: Legionella pneumophila are gram-negative rods. They are very difficult to culture because of their complex nutrient requirements, such as cysteine, high concentrations of iron, and the use of activated charcoal agar. They survive as intracellular pathogens of either protozoa or human macrophages. They are most often found in stagnant water reservoirs like air conditioning cooling towers, whirlpool spas, humidifiers, faucets and shower heads, and are infectious when inhaled. L. pneumophila was first identified and named after the American Legion convention of 1976, held in Philadelphia, PA.
National Oceanic and Atmospheric Administration (NOAA)/National Climatic Data Center (NCDC), (2001). U.S. Tornado Climatology. Accessed on 9//27/2011 at http://www.ncdc.noaa.gov/oa/climate/severeweather/tornadoes.html#deadly
1. According to the USA Today Tornado Information website, a tornado is a "violently rotating column of air in contact with the ground and pendant from a thunderstorm." Therefore, thunderstorms are the first step in the creation of a tornado.
The swiftness, beauty, and absolute daunting sight of tornadoes have haunted minds and pulled at the curiosity of many. As Mother Nature’s fiercest windstorms, tornadoes do not simply lift you up and transport you to the magical Land of Oz. Rather, they habitually throw you around like a rag doll leaving a disaster behind them. Interestingly enough, tornadoes are yet to be fully understood. We know what a tornado is and how it forms but why it forms under various circumstances and not others is still under scrutiny.
...ed for the worse, eventually leading up to Janie killing Tea Cake in self-defense. Janie experienced true grief and guilt for Tea Cake’s death, unlike the forced grief she showed everyone in Eatonville when Jody died. This grief, along with the disloyalty of her former friends during trial, makes Janie realize that she can survive on her own; Tea Cake’s death completes Janie’s journey to self-discovery.
... and quickly grow. Secondly, invasins help the bacteria spread in the host’s tissues. An invasion is a protein that acts locally to damage host cells to facilitate the growth and spread of the pathogen. More simply, Staphylococcus aureus and Streptococcus pyogens have a small army of invasins that basically attack the host very quickly and spread the bacteria out far – into the blood and organs. Another virulence factor of both Staphylococcus aureus and Streptococcus pyogens is their cellular secretions. The secretions include antigens, enzymes, and toxins that assist with various functions needed to feed the bacteria and fend off the host’s immune defences.
A tornado occurs in very powerful thunderstorms, and usually it occurs in a super cell. A super cell is a type of storm that already has rotation inside of it, called a mesocycle. A tornado begins to form when a downdraft of air pulls the mesocycle down towards the ground. A funnel begins to form, and when the funnel cloud finally touches down, it officially becomes a tornado. As warm, moist air (the fuel of a tornado) is drawn into the tornado, it matures...
On Janie’s quest for self-fulfillment, she realizes that she must live for hers to find the love that she needs and wants. Security and status do not equal love these unnatural things caused her marriage to Logan and Joe to be unsuccessful. When Janie meets, Teacake it is his natural aura that complements Janie because the novel shows us that nature is her identity.
Tornadoes are formed typically during a front of stormy weather known as a supercell, although not always. It begins with cold air and warm air that collide. This causes the cold air to drop and the warm air to rise and spin into a funnel. However, before the funnel can develop, a series of steps must occur leading up to the storm. First, a change in wind direction and an increase in wind speed must occur which will happen with an increasing altitude. This creates an effect of invisible horizontal spinning which occurs in the lower atmosphere. Next, rising air in the thunderstorm tilts the rotating air from horizontal to vertical. Then, the 2-6 mile wide area of rotation must be kept within the majority of the storm. The final step is for a low cloud base containing no rain to form a funnel cloud, creating the tornado. Tornadoes follow a very specific and definite life cycle.
Bacterial cells, like plant cells, are surrounded by a cell wall. However, bacterial cell walls are made up of polysaccharide chains linked to amino acids, while plant cell walls are made up of cellulose, which contains no amino acids. Many bacteria secrete a slimy capsule around the outside of the cell wall. The capsule provides additional protection for the cell. Many of the bacteria that cause diseases in animals are surrounded by a capsule. The capsule prevents the white blood cells and antibodies from destroying the invading bacterium. Inside the capsule and the cell wall is the cell membrane. In aerobic bacteria, the reactions of cellular respiration take place on fingerlike infoldings of the cell membrane. Ribosomes are scattered throughout the cytoplasm, and the DNA is generally found in the center of the cell. Many bacilli and spirilla have flagella, which are used for locomotion in water. A few types of bacteria that lack flagella move by gliding on a surface. However, the mechanism of this gliding motion is unknown. Most bacteria are aerobic, they require free oxygen to carry on cellular respiration. Some bacteria, called facultatibe anaerobes can live in either the presence or absence of free oxygen. They obtain energy either by aerobic respiration when oxygen is present or by fermentation when oxygen is absent. Still other bacteria cannot live in the presence of oxygen. These are called obligate anaerobes. Such bacteria obtain energy only fermentation. Through fermentation, different groups of bacteria produce a wide variety of organic compounds. Besides ethyl alcohol and lactic acid, bacterial fermentation can produce acetic acid, acetone, butyl alcohol, glycol, butyric acid, propionic acid, and methane, the main component of natural gas. Most bacteria are heterotrophic bacteria are either saprophytes or parasites. Saprophytes feed on the remains of dead plants and animals, and ordinarily do not cause disease. They release digestive enzymes onto the organic matter. The enzymes breakdown the large food molecules into smaller molecules, which are absorbed by the bacterial cells. Parasites live on or in living organisms, and may cause disease. A few types of bacteria are Autotrophic, they can synthesize the organic nutrients they require from inorganic substances. Autotrophic bacteria are either photosynthetic or Chemosynthetic. The photosynthetic bacteria contain chlorophyll that are different from the plant chlorophyll. In bacterial photosynthesis, hydrogen is obtained by the splitting of compounds other than water.
A tornado is a violent windstorm characterized by a twisting, funnel-shaped cloud. It is spawned by a thunderstorm (or sometimes as a result of a hurricane) and produced when cool air overrides a layer of warm air, forcing the warm air to rise rapidly. Tornadoes can cause a lot of damage and even deaths. The damage from a tornado is a result of the high wind velocity and wind-blown debris. Tornado season is generally March through August, although tornadoes can occur at any time of year. They tend to occur in the afternoons and evenings: over 80 percent of all tornadoes strike between noon and midnight. From 1950-1995 the total number of tornadoes in Michigan was 722, with an average of 5 deaths and 3,217 injuries (70 a year average) resulting from the storm a year.
All thunderstorms are characterized by updrafts, rising air currents which supply the warm, humid air that fuels thunderstorms; sometimes, however, the column of rising air becomes a vortex—a funnel cloud, or if it reaches the ground, a tornado. A tornado is often located at the edge of an updraft, next to air coming down from the thunderstorm with falling rain or hail. This explains why a burst of heavy rain or hail sometimes announces a tornado’s arrival. As air rises from the ground in the tornado’s vortex, a low-pressure area is created near the ground. Air rushes to fill this area, causing additional damaging to areas not directly hit by the tornado. As air rushes into the vortex, its pressure lowers, cooling the air. T...