A Study of Prejudice in Harper Lees To Kill a Mockingbird Research Paper Example

A Study of Prejudice in Harper Lees To Kill a Mockingbird Research Paper Example A Study of Prejudice in Harper Lees To Kill a Mockingbird Paper A Study of Prejudice in Harper Lees To Kill a Mockingbird Paper Essay Topic: A Woman Killed With Kindness Literature To Kill a Mockingbird We see in the novel To Kill a Mockingbird, by Harper Lee an assortment of racial, social, religious and gender prejudice. The narrative is set in the small town of Maycomb, located in Alabama. The era is the early 1930s, a very prejudiced time in the southern states of America. This period of history was also the time of the Great Depression that occurred due to the Wall Street Crash in 1929. This novel is based upon a court case of a black man that is accused of the rape of a white woman. This tale is split up into two different parts. Part one introduces the main characters and portrays the several different prejudices which they both feel and experience. The second part of this novel presents the case of Tom Robinson, the black man. To Kill a Mockingbird focuses predominantly on the subject of racial prejudice throughout its entirety. There were an excessive amount of prejudice people at this time in the southern states. The Civil War ended in 1876, giving the blacks their deserved freedom from slavery. Even though the war had come to a close so long before the story takes place, in the 1930s, racial tension is still very high. There is strain between the blacks and the whites because the blacks legally are not subject to the whites anymore, yet the whites do not want to change their ways of living above the blacks, with the blacks under their authority. Even the small town of Maycomb was greatly overruled by the prejudices of whites; Atticus, his family, and Miss Maudie, are shown as the only unprejudiced people throughout the whole of the Maycomb County. Mr Ewell, the man who accuses Tom Robinson of raping his daughter, is by far the most prejudiced man in the whole novel. We see this right after the trial when Bob Ewell stops Atticus on the post office corner, spits in his face and says, according to Miss Stephanie Crawford, Hed get him if it took the rest of his life. The reader might consider that this doesnt show prejudice, but we see that throughout the novel Bob Ewell hates the unprejudice white people like Atticus. We see later on in the book that Tom Robinson is probably innocent and falsely accused. Because of Mr Ewell accusing Tom and causing his conviction, this eventually brings about the death of Tom. The black community is presented throughout the story in a very positive light. The Finchs maid is a loving, tender-hearted woman, who cares for Jem and Scout, bringing them up as if they were her own children, disciplining them at appropriate times, and giving them a mothers love. Tom Robinson is a very hard-working family man, praised by his employer, that That boys worked for me for eight years and I aint had a speck o trouble outa him. Not a speck. His kindness is shown in his feelings for Mayella Ewell, he felt right sorry for her. After the trial, when Calpurnia brings Atticus into the kitchen the next morning, the kitchen table was loaded with enough food to bury the family, brought by the black community, because they preciate what you did, Mr Finch. Gender prejudice is focused on in this book a great deal less than racial prejudice. Gender prejudice is defined as attributing certain characteristics to one sex or other which is not based on reason or experience. Jem told me I was being a girl, that girls always imagined things. We see that women were treated more as servants and maids than as wives and helpers in the 1930s. They were not allowed to sit on a jury because they were considered too frail. At the beginning of the book, Scout relates, I sat at the little table in the dining room; Jem and Francis sat with the adults at the dinning table. Scout feels that Aunty dislikes her because she isnt enough of a lady. We believe Scouts aunt is unreasonable in her demand on her to sit alone, because at such a young age it is abnormal for a young girl to sit still and try to be a lady. Throughout the novel, Scout is constantly embarrassed by, or embarrasses her aunty because of her continuous tom-boy attitude. The second strongest discrimination that is shown in this story is the social prejudice of Maycomb County. The Ewells are perceived as low down people, because they are poor and dirty and never going to school. They are despised by the middle class almost as much as blacks of Maycomb. Another poor family that is depicted, is the Cunninghams. When Walter Cunningham comes over for dinner, he poured syrup on his vegetables, and meatand probably would have poured it into his milk glass if (Scout) hadnt asked him what the sam hill he was doing. The book displays the Cunninghams as honest and upright people, they never took anything they couldnt pay back but because of their poverty they are looked down upon in the society. One of the Cunninghams sat on the jury during Tom Robinsons trial, in the beginning he was rarin for an outright acquittal. The Radleys, Jem and Scouts next door neighbour, have a son named Arthur Radley but all the children in the neighbourhood call him Boo. There is social prejudice shown here, in that he is not accepted because he is different from most people. The reason the children call him Boo is because for years time no one had seen him and the kids imagined him to be a ghost. There was a incident when Boo was thirty years of age he stabbed his father in the leg with a pair of scissors. Boo was imprisoned in the basement of the county jail until one day his father took him home and he was never seen again. Inside the house lived a malevolent phantom Any stealthy crimes committed in Maycomb were his work. The pecans from the Radley tree fall into the school yard, but they lay untouched because Radley pecans would kill youfolks say he pizened em and put em over on the school side of the fence. This shows how intolerant the county is against Boo, just for one crime he is sent to jail and is never seen again after his father takes him home. No one really knows Boo Radley but he is suspected by all that he is a crook and a killer. This is displayed, one September afternoon, Scout nearly smashes a roly-poly but is stopped by her brother. She asks, Why couldnt I mash him? Jem says, Because they dont bother you. Jem is learning to empathize with others, including Boo. You can shoot all the blue jays you want, but it is a sin to kill a mockingbird. Atticus told the children when they received air rifles. Miss Maudie explained Your father is right, mockingbirds dont do one thing but make music for us to enjoy. They dont eat up peoples gardens, dont nest in corncribs, they dont do one thing but sing their hearts out for us. That is way its a sin to kill a mockingbird. Mockingbirds here symbolize both Tom Robinson and Boo Radley. These two persons are harmless to society, yet because of the time and age, they are looked down upon and despised. This is the real sin, because they are not only harmless, but defenceless. Religious prejudice plays a small part in the book, when Cal, the familys black maid, took the children to a black church named First Purchase African M.E. Church. There was a big, tall Black woman called Lula and she objected to Cal bringing Scout and Jem to the black church. Lula wants to know why you bringin white chillum to a nigger church. This shows that the churches are segregated from each other, and that the Black church does not accept white people and the white church does not accept the Black people. We see later on that the children are asked to stay; this is because their father Atticus is not prejudiced and is defending Tom Robinson. The discrimination and intolerance that Harper Lee is really trying to expose is racial prejudice. This book has caused millions of people to consider the effect that racial prejudice really has. Tom Robinson is killed trying to escape from jail, because although Atticus proved that he was innocent, the jury still convicted him. The story ends with Boo finally coming out of his house, to save Jem and Scout from Mr Ewell, who tries to kill them, showing the children that the way that had imagined Boo was wrong. Over-all, this book teaches everyone something important about prejudice and how to live in the world today.

buy custom Ameribus International essay

buy custom Ameribus International essay This is paper which gives specific answers to a set of four questions which are mainly touching on the business organizations depending on each other and how such dependence is implemented through joint activities or alliances. The first question touch a multinational company Ameribus and the question seeks to clarify which strategy can be used in countering the stiff competition from similar competing companies. The other four questions touch on the other companies with similar objective of enlarging the market that they sell their goods in. In the case of Ameribus International it is clear that there is an urgent need for the company to change its marketing tactics in order to be relevant and command some presence in the market among its rivals who seem to be taking two steps at a time ahead of the company. When a company is in such a position, the leaders ought to make a very carefully analysis of both the market and the rival companies. The strategy that Ameribus will take will depend more on which steps the rival companies have taken and also the market situation. It should be noted that in our case the leadership of Ameribus will play a great role in navigating the company on a path to commanding a good market presence. Given the two options of either transforming into a global or a transnational organization, the role of leadership will play a great part in determining the strategy which Ameribus takes. The leaders role in the short term future is impacted by the present information revolution. This affects the process of leadership by speeding up the inputs, requiring faster and more personal transformation of the product, all in a business climate that builds competition through response time to customer demands. This section is going to look at what should be done for Ameribus to become a global organization. Arguing from the point that already there are other companies in the market which can be said to firm on their market shar then Ameribus will need to adopt the GEMS {(Global Economic Management System) check the chart at the appendices} model which brings together historical, institutional, and regulatory factors. This model contains a multiple of factors which if well implemented will ass ist Ameribus in effectively going global and ensuring that it secures a good portion of the market which seems to be already dominated by its competitors (Porter, n.d.). The model is structured into soft and hard factors. The hard factors are listed as anchor effect, government policy, the agglomeration effects and historical factors. The soft factors in this model include the business climate, innovation and entrepreneurship, element of chance and industry networks. The consideration of all these factors will enable Ameribus to compete effectively. Some of the significant factors which Ameribus should look out for in the course of going global include factors conditions which include the infrastructure, capital and labor availability. The demand conditions like wise ought to be taken into consideration whereby factors such size, growth and proximity of the market is taken into consideration. Other significant factors to be given serious considerations include the supporting industries, public policy, socio-political climate, inter-firm linkages and element of chance (Porter, n.d.). The company leaders should be sensitive to the market dynamics especially where the rival companies command some presence. By going global and being sensitive, it will be make it possible for the company to reach out to the customers amidst the presence of the rival companies. First the managers of Ameribus should be able to scan the global environments, identify relevant opportunities and threats, and design responses that will satisfy customers in ways that competitors cant easily imitate and make sure that these plans are implemented, even as they compete across a variety of geographies. They must be able to accuratelyy sense changes in their competitive environment, including potential shifts in technology, competition, customers, and regulation, and must act on these opportunities and threats; to be able to seize them by reconfiguring them to meet new challenges (Kuglin and Hook 2002). It must capitalize on human resource management in all the continents to maximize on the potential of workers in the profitable bottom line of the organization. This should be done through training programs to give employees necessary information to do their jobs better. For Ameribus to globalize it must also employ what is called acquisition strategy. This helps in deregulation of multiple industries in many different economies, this increases market power, overcomes entry barriers to new markets or regions, avoids the cost of developing new products and increases the speed of new market entries, it reduces the risk of entering a new business. It will also help them diversify and reshape their competitive scope. According to Michael, Duane and Robert (2008), it is very significant for a business to employ enterprise systems to enable it value creation. In summary form, what ought to be done in order to enable a company to carry out the process of globalization successfully: First if globalization should be an option for the company to take. The leadership should then have the destination of the company in mind. It is recommended that with the globalization process, the reaching out of foreign countries should be carried out on a one by one basis. Another step to be undertaken is to research on the targeted market so as to come up with a proper marketing which best suits the area in question. Others which ought to be taken into consideration include visiting the market, writing a plan, forming strong allianceand making consultation from experts. A point to strongly put across is that when a company is being globalized it ought to be culturally very sensitive to the new region where anticipates to make its functions (Kuglin and Hook 2002). Buy custom Ameribus International essay

Asymmetric Synthesis Essay Example | Topics and Well Written Essays - 1000 words

Asymmetric Synthesis - Essay Example Hence, it is undeniably interesting to study the catalytic asymmetric synthesis of cinchona alkaloids , which have also been helpful in man's daily living. This includes its role in the production of food flavorings and medicines for different ailments like malaria. Additionally, the popularity of cinchona alkaloids over the years is also because of its qualifications in the three primary criteria of catalysts, which are as follows: 1) the diversity of reactions that the catalyst can trigger; 2) the accessibility of both enantiomeric antipodes of the catalyst at an affordable cost; and 3) the stability of the catalyst. The research aims to study the catalytic asymmetric synthesis of the popular two pairs of cinchona alkaloids which are enantiomeric in nature: cinchonine and cinchonidine, and; quinine and quinidine. The researcher aims to study the two pairs by isolating them through extraction of the bark of the cinchona tree; a native of tropical regions. Due to their widespread use, all four members are readily available in large quantities from most chemical suppliers. Furthermore, before conducting several experiments for the research, the researcher will gather enough materials documenting the history of cinchona alkaloids. ... erature section of the research, which will include information about cinchona alkaloids from one of the earliest uses of cinchona alkaloids in asymmetric catalysis which was demonstrated by Pracejus in the 1960's to catalyze the asymmetric alcoholysis of ketenes (Pracejus, 1964) to its modern uses. Moreover, the study's related literature will consist of theories proposed about the asymmetric synthesis of cinchona alkaloids by chemists of different ages. One interesting theory which will contribute to the study of the alkaloid's catalytic asymmetric synthesis is that the alcohol is activated via a hydrogen bond with the tertiary amine of benzoylquinine. Addition of the alcohol to the ketene is followed by quenching of the resultant enolate by the chiral ammonium salt. The resultant esters are isolated in up to 76% enantiomeric excess. The research will strive to replicate the experiments conducted to support this theory. Also, with the proliferation of recent publications studying cinchona-ketene systems for asymmetric synthesis (Blake, 2001), the study will investigate different assumptions about the asymmetry in the synthesis of cinchona alkaloids. One of the most noticeable of these recent publications which the researcher intends to focus is Lectka's -halogenation of acid chlorides (Wack, 2001). Lectka stated that the benzoylquinine-ketene system reacts with quinone based electrophilic halogenating reagents to yield activated -halogenated esters with enantioselectivities as high as 99%, and with good yields. The study will try to prove this through catalytic asymmetric fluorination, where cinchona derivatives have already been used, though only stoichiometrically (Muiz, 2001). However, despite the efforts to base certain experiments upon previous studies, the

Corporatocracy Personal Statement Example | Topics and Well Written Essays - 250 words

Corporatocracy - Personal Statement Example The wealthy elite have the capacity to bribe government officials because of their financial clout; thus, they are able to rule the society. This to me is a system that does not benefit the currently struggling American family. As a Pakistani national who belongs to one of the influential political families in the country, being politically victimized in the late 1990s by the government provided the impetus for one’s decision to delve into the Foreign Service career. One decided to live in New York for the past two years to pursue higher education. I have witnessed western politics during this span of time and had the opportunity to compare Western politics and the ruling corporatocracy. The greed and tyranny of corporatocracy pushes the economy further down because it only benefits corporate executives and politicians. Their very existence is driven by selfish interests and therefore failed to consider social responsibility and utilitarianism. If corporations are not able to achieve the profit that they want because of legal impediments, their preferred option is to give unlimited campaign donations to politicians who can push for legislations that will benefit their companies. Hopefully, a career in Foreign Service will be my stepping stone towards the achievement of both personal and professional goals of trying to educate and convince people in corporations and governments, as well as the general public, that corporatocracy is not the answer to the economic and financial woes of the

Reflection papers#4 Essay Example | Topics and Well Written Essays - 750 words

Reflection papers#4 - Essay Example The punishment to fire that huge amount of people involved in corruption or those likely to be involved is acceptable. Even though the number of people sacked due to the corruption charges was extremely large, it is wise to eliminate them than try to change them (Watson, 2015). This is because; corruption does a lot of damage to the company than any other misconduct. First of all, corruption taints the image and reputation of a company and in fact for such an international company this is shameful and irreparable. Secondly, corruption threatens the very future of a company since money is used for personal things while the company’s needs are neglected. This leads to bad work environment, reduction of employee’s salaries and more. Thirdly, corruption leads to low quality standards of goods produced by a company which is corrupt. This is because they will take bribes and offer contracts to undeserving people furthermore, the work ethics will be poor since the workforce wi ll be full of incompetent people who bribed their way in to the company. Lastly, corruption will means that employees suffer at the hands of their fellow co workers and people with power since any charges will just be bribed and brushed off without fair and just consideration. This will also make many people be fired unjustly if the bosses feel like it. If I were the new chief ethics officer I would have handled the situation nearly the same way. However, I would have not fired everybody who was alleged to be in the corruption game. I would have used tact to find out the real ring leaders and not blame everybody in the departments. Even though bribery was legal in German until 1999, the corruption at Siemens was not justified (Watson, 2015). A leading international company like Siemens had a reputation to keep even when the vice was legal. A company can sign code and conduct contracts with employees upon employment where they are asked if

Types of Tissue and Muscle

Types of Tissue and Muscle Muscle Muscle is one of the four fundamental types of tissue present in animals. It is a soft tissue primarily responsible to produce movement of a body part. Its cells convert the chemical energy of ATP into the mechanical energy of motion and exert a useful pull on another tissue. More specifically, muscle contraction serves the following overlapping functions: movement and contractile move of body contents in the course of respiration, circulation, digestion, defecation, urination, and childbirth. Stability by resisting the pull of gravity. Communication. As well as the control of body openings and passages. And finally, producing around 85% of our body heat, which is vital for the metabolism (Carey Carpenter, 2007). Classification There are three histological types of muscle—cardiac, smooth and skeletal—which differ in appearance, physiology, and function. The cardiac muscle is essentially limited to the heart, though it extends slightly into the nearby blood vessels. It is involuntary and striated because of the regular arrangement of their actin and myosin filaments. Its cells are much shorter, so they are commonly called myocytes, and are mononuclated (Saladin, 2003). The myocytes assemble branches of adjoining cells and form a network by attaching to each other in attachment points called intercalated discs that provide strong mechanical adhesions between adjacent cells. Smooth muscle lacks striations and is involuntary. Smooth muscle cells are usually long and spindle-shaped, and each fusiform cell has a single and centered nucleus (Purves et al., 2004). Small amounts of smooth muscle are found in the iris of the eye and in the skin, but most of it, called visceral muscle, forms layers in the walls of the digestive, respiratory, and urinary tracts, blood vessels, the uterus, and other viscersa (Alberts et al., 2008). The skeletal muscle type is of special interest of this thesis and will be further studied in the following sections. Skeletal muscle Skeletal muscles are, as the name implies, are bound to the skeleton by means of tendons, which means that they are volitional. It is composed of both muscular tissue and connective. A skeletal muscle cell (muscle fiber) is about 10 to 100m in diameter and 30 cm long. It is surrounded by a sparse layer of areolar connective tissue called the endomysium, which allows room for blood capillaries and nerve fibers to reach each muscle fiber. Muscle fibers are grouped in bundles called fascicles, which are visible to the naked eye as parallel strands. Each fascicle is separated from neighboring ones by a connective tissue sheath called the perimysium, usually somewhat thicker than the endomysium. The muscle as a whole is surrounded by still another connective tissue layer, the epimysium. The epimysium grades imperceptibly into connective tissue sheets called fasciae, deep fasciae between adjacent muscles and a superficial fascia (hypodermis) between the muscles and skin. It is described as striated and voluntary (Saladin, 2003). Structure The skeletal muscle tissue consists of long and cylindrical cells called muscle fibers, which are actually huge single cells that form during development by the fusion of many separate cells, called myoblasts. Each cell contains multiple nuclei adjacent to the plasma membrane, and they are about 10 to 100m in diameter and 30 cm long. The bulk of the cytoplasm inside is made up of myofibrils, which is the name given to the basic contractile elements of the muscle cell. Within each myofibril are thin actin filaments and thick specific muscle isoforms of myosin II filaments (Alberts et al., 2008). Myosin filaments are bundles of molecules with globular heads and polypeptide tails. Actin filaments consist of two chains of actin monomers twisted together. They are wrapped by chains of the polypeptide tropomyosin and studded at intervals with another protein, troponin. In most regions of the myofibril, each thick myosin filament is surrounded by six thin actin filaments, and conversely, each thin actin filament sits within a triangle of three thick myosin filaments. The myofibril consists of repeating units, called sarcomeres, which are the units of contraction, built up of approximately 2.2 microns in length. Each sarcomere is made of overlapping filaments of actin and myosin, which create a distinct band pattern. As the muscle contracts, the sarcomeres shorten, and the appearance of the band pattern changes. Each sarcomere is bounded by Z-lines, which are structures that anchor the thin actin filaments. Centered in the sarcomere is the A-band, which contains all the myosin filaments. The H-zone and the I-band, are regions where actin and myosin filaments do not overlap in the relaxed muscle. The dark stripe within the H-zone is called the M-band; it contains proteins that help hold the myosin filaments in their regular arrangement. The bundles of myosin filaments are held in a centered position within the sarcomere by a protein called titin. Cardiac muscle and smooth muscle also contain sarcomeres, although the organization is not as regular as that in skeletal muscle (Alberts et al., 2008; Purves et al., 2004.). The plasma membrane, called the sarcolemma has tunnel-like infoldings called transverse (T) tubules that penetrate through the fiber and emerge on the other side. The function of a T tubule is to carry an electrical current from the surface of the cell to the interior when the cell is stimulated. Most other organelles of the cell, such as mitochondria and smooth endoplasmic reticulum (ER), are located between adjacent myofibrils. The sarcoplasm also contains an abundance of glycogen, which provides stored energy for the muscle to use during exercise, and a red pigment called myoglobin, which binds oxygen until it is needed for muscular activity. The smooth ER of a muscle fiber is called sarcoplasmic reticulum (SR). It forms a network around each myofibril, and alongside the T tubules it exhibits dilated sacs called terminal cisternae. The SR is a reservoir for calcium ions; it has gated channels in its membrane that can release a flood of calcium into the cytosol, where the calcium a ctivates the muscle contraction process (Saladin, 2003). Muscle contraction For contraction to occur, an action potentials spreads from the end plate and when it reaches the T tubules, it continues down them into the sarcoplasm. Action potentials open voltage-regulated ion gates in the T tubules. These are physically linked to calcium channels in the terminal cisternae of the sarcoplasmic reticulum (SR), so gates in the SR open as well and calcium ions diffuse out of the SR, down their concentration gradient and into the cytosol. The calcium ions bind to the troponin of the thin filaments. The troponin-tropomyosin complex changes shape and shifts to a new position. This exposes the active sites on the actin filaments and makes them available for binding to myosin heads; the myosin heads must have an ATP molecule bound to it to initiate the contraction process. Myosin ATPase, an enzyme in the head, hydrolyzes this ATP. The energy released by this process activates the head, which â€Å"cocks† into an extended, high-energy position. The head temporarily keeps the ADP and phosphate group bound to it. The cocked myosin binds to an active site on the thin filament. Myosin releases the ADP and phosphate and flexes into a bent, low-energy position, tugging the thin filament along with it. This is called the power stroke. The head remains bound to actin until it binds a new ATP. Upon binding more ATP, myosin releases the actin. It is now prepared to repeat the whole process—it will hydrolyze the ATP, recock (the recovery stroke), attach to a new active site farther down the  thin filament, and produce another power stroke (Saladin, 2003). Classes of muscle fibers Not all muscle fibers are metabolically alike or adapted to perform the same task. Some respond slowly but are relatively resistant to fatigue, while others respond more quickly but also fatigue quickly. Indeed, skeletal muscles can be divided into fast and slow twitch fibers and its myosin heavy chain (MHC) isoform expression. Type I (MHC-I): Also called slow oxidative (SO) or slow-twitch. These fibers have relatively abundant mitochondria, myoglobin, and blood capillaries, and therefore a relatively deep red color. They are well adapted to aerobic respiration, which does not generate lactic acid. Thus, these fibers do not fatigue easily. However, in response to a single stimulus, they exhibit a relatively long twitch, lasting about 100 milliseconds (msec). Type II (MHC-II): Also called fast glycolytic (FG) or fast-twitch. They are well adapted for quick responses but not for fatigue resistance. They are rich in enzymes of the phosphagen and glycogen–lactic acid systems. Their sarcoplasmic reticulum releases and reabsorbs Ca2 quickly, which partially accounts for their quick, forceful contractions. They are relatively pale (white fibers). These fibers produce twitches as short as 7.5 msec, but because of the lactic acid they generate, they fatigue more easily than SO fibers. Some authorities recognize two subtypes of FG fibers called types MHC-IIA and MHC-IIB. Type IIB is the common type just described, while IIA, or intermediate fibers, combine fast-twitch responses with aerobic fatigue-resistant metabolism. Type IIA fibers, however, are relatively rare except in some endurance-trained athletes (Saladin, 2003). Notably, human skeletal muscle does not contain MHCIIb (Spangenburg and Booth, 2003; Schiaffino and Reggiani, 1994; Smerdu et al., 1994). In addition, ‘‘hybrid’’ fibers containing two MHC isoforms (i.e., type I/IIA, IIAX, IIXB) can also be present in muscle (Schiaffino and Reggiani, 1994; Staron and Pette, 1993). The fiber types can be differentiated histologically by using stains for certain mitochondrial enzymes and other cellular components, like using immunohistochemical procedures with antibodies against the specific MHC isoforms (Schiaffino et al., 1989; Lucas et al., 2000). All muscle fibers of one motor unit belong to the same physiological type. Nearly all muscles are composed of both SO and FG fibers, but the proportions of these fiber types differ from one muscle to another. Muscle myogenesis Vertebrate skeletal myogenesis proceeds through three stages: determination of the muscle progenitor cells, called myoblasts; proliferation and in some cases migration of myoblasts; and their terminal differentiation into mature muscle by fusing to form multinucleated myotubes (Buckingham et al., 2003; Shi and Garry, 2006). Muscle development Muscle tissuesare derived from themesodermallayer of embryonicgerm cellsin a process known asmyogenesis. All muscles are derived fromparaxial mesoderm [8].The paraxial mesoderm is divided along the embryos length intosomites, corresponding to thesegmentationof the body.Muscle cells come from two cell lineages in the myotome somite, the epimere and hypomere, which formepaxialandhypaxialmuscles, respectively. Most muscles are hypaxial. During development,myoblasts either remain in the somite to form muscles associated with the vertebral column or migrate out into the body to form all other muscles. Myoblast migration is preceded by the formation ofconnective tissueframeworks, usually formed from the somaticlateral plate mesoderm.Myoblasts follow chemical signals to the appropriate locations, where they fuse into elongate skeletal muscle cells (Sweeney, 1997). Muscle differentiation Muscle fibersform from the fusion ofmyoblastsinto multi-nucleated fibers calledmyotubes. In the early development of an embryothese myoblasts will proliferate if enoughfibroblast growth factor(FGF) is present, without differentiating. When these factors are depleted, the myoblasts cease division and secretefibronectinonto theirextracellular matrix and bind to it through _5ÃŽ ²1 integrin, their major fibronectin receptor (Menko and Boettiger 1987; Boettiger et al. 1995). The second stage involves the alignment of the myoblasts together into chains and subsequently into myotubes. This step is mediated by cell membrane glycoproteins, including several cadherins and CAMs (Knudsen 1985: Knudsen et al. 1990). Recognition and alignment between cells takes place only if the two cells are myoblasts. However, identity of the species is not critical (Yaffe and Feldman, 1965). The third stage is the actual cell fusion itself. In this stage,calciumions are critical for development (Shainberg et al. 1969; David et al. 1981). Fusion is mediated by a set of metalloproteinasescalledmeltrins (e.g., c-Met).Myocyte enhancer factors(MEFs) promote myogenesis.Serum response factor(SRF) plays a central role during myogenesis, being required for the expression of striated alpha-actin genes (Wei et al., 1998).Expression of skeletalalpha-actinis also regulated by theandrogen receptor; steroids can thereby regulate myogenesis (Vlahopoulos et al., 2005). The specific extracellular signals that induce determination of each group of myoblasts are expressed only transiently. These signals trigger production of intracellular factors that maintain the myogenic program after the inducing signals are gone. We discuss the identification and functions of these myogenic proteins, and their interactions, in the next several sections. Muscle-specific transcription factors Pax family Satellite cells and proliferating myoblasts is characterized by the expression of Pax-genes, more specifically Pax7 and Pax3, which are transcription factors that regulate proliferation. Back to the developmental stage, in the lateral portion of the somite, which forms the hypaxial muscles, factors from the surrounding environment induce the Pax3 transcription factor. In the absence of other inhibitory transcription, Pax3 then activates the genes encoding two muscle-specific transcription factors, Myf5 and MyoD. In the medial region of the somite, which forms the epaxial muscles, MyoD is induced through a slightly different pathway[1]. Pax7 residing satellite cells proliferating stage and Pax7 knockout mice completely lack satellite cells (Seale et al., 2000). Cells expressing Pax7 is believed to be important for the regeneration of myoblasts. Also the expression of Pax3 has negative effect on the differentiation and it has been shown that this transcription factor is down-regulated in muscle by ubiquitination and proteasomal degradation before differentiation can proceed (Boutet et al., 2007). Pax genes have been shown to regulate the proliferation and survival even of certain cancers such as melanoma (Muratovska et al., 2003). Pax transcription factors are downregulated upon further differentiation and other proteins predominate. Meanwhile Pax3 _____, Pax7 appears only in muscle stem cells (___). MyoD family Muscle cells come from two cell lineages in the somite. In both instances, paracrine factors instruct the myotome cells to become muscles by inducing them to synthesize the MyoD proteins (Maroto et al. 1997; Tajbakhsh et al. 1997). Or also called the myogenic bHLH (basic helix-loop-helix) proteins. The proteins of this family all bind to similar sites on the DNA and activate muscle-specific genes (e.g. the muscle-specific creatine phosphokinase gene by binding to the DNA immediately upstream from it, or the chicken muscle acetylcholine receptor) (Lassar et al. 1989; Piette et al. 1990). MyoD and Myf5 belong to this family and are particularly important for muscle differentiation [2]. Their important role during differentiation is supported by the MyoD-/-/Myf-5-/- mice lacking fully developed skeletal muscle (Rudnicki et al., 1993). Myf-5 promotes myoblasts’ proliferation and is required for the cells to initiate differentiation (Ustanina et al., 2007). Absence of MyoD inhibits differentiation in cell culture and the protein is therefore considered to be a positive regulator of the process (Sabourin et al., 1999). While Pax3 is found in several other cell types, the myogenic bHLH proteins are specific for muscle cells. Any cell making a myogenic bHLH transcription factor such as MyoD or Myf5 is committed to becoming a muscle cell. Myogenic regulatory factors (proper name?) Later than the MyoD proteins expression during differentiation, the myogenin and the myogenic regulatory factor 4 (MRF4) are present. Mice with deleted myogenin in developing myoblasts can start the differentiation process but they cannot move and die soon after birth (Hasty et al., 1993). Among other things, this suggests that myogenin is required at a later stage of the process. Similarly, MRF4 is important for the growth of muscle tissue (Rhodes and Konieczny, 1989). It is noted that the MEF2 family of transcription factors also regulate differentiation (Olson et al., 1995), but their functions are not described in this context. In summary, Pax transcription factors help to sustain it from the stem cell stage of satellite cells, MyoD and Myf-5 act as myogenic determinants in the myoblast’s diet, and myogenin and MRF4 are known as regulators of the later differentiation and muscle fiber formation (Pallari, 2011). Other factors Although some factors that induce differentiation remain unknown, some growth factors and signaling molecules have been shown to regulate the process. Notch signaling is important in animal embryonic development, in that it participates in the cell fate determination (Alberts et al., 2008). Notch has a dual role of myoblasts in that the protein has an inhibitory effect on myoblasts differentiation (Shawber et al., 1996) and simultaneously stimulates their proliferation (Conboy and Rando, 2002). The chemoattractant SDF-1 also has an inhibitory effect on myoblasts differentiation and stimulates their proliferation by activation of the PKCÃŽ ¶ (Ãâ€"demiÃ…Å ¸ et al., 2007). Moreover, differentiation requires the expression and activity of cyclindependent kinase (Cdk) inhibitors, such as p21 and p27, critical for the withdrawal of myoblasts from the cell cycle (Kitzmann and Fernandez, 2001). To fully understand the factors that regulate, activate and inhibit satellite cells and their differentiation requires even much research (Kuang and Rudnicki, 2007; Shi and Garry, 2006.). [1] developmental biology Scott gilbert [2] developmental biology Scott gilbert

North Korea Surprise Attack :: essays research papers

In 1949, Congress dragged its feet in considering a $150 million dollar aid bill to South Korea. Syngman Rhee had so often talked about invading North Korea that US leaders feared giving him too much in the way of weapons. For this reason, South Korea was sent only rifles, bazookas, and light artillery; tanks an airplanes were held back. Also by 1949, most of the US military had moved out. Only 500 advisors, known as KMAG (the Korean Military Advisory Group) remained in South Korea, under the command of Brigadier-General William L. Roberts. In January of 1950, the House defeated the Korean Aid Bill by a single vote; Korea was scheduled no to get American Aid for the following year, 1950. On June 25, 1950 the North Korean army attacked South Korea, crossing the 38th Parallel. Pentagon officials were stunned, and had no immediate contingency plan ready. Some said little could be done, while others suggested it was the beginning of Stalin's plot to take over the world. Truman and his circle of advisers sat firmly in this latter group. Immediately upon the invasion, these advisors discussed the prospect of sending General Douglas MacArthur, the US commander in the Far East, to lead a military response. The North Korean invaders hoped to take Seoul, the South Korean capital, as quickly as possible. The majority of ROK forces were routed by North Korean troops. Only one ROK division, the 6th, held its ground. John Muccio, the American ambassador to South Korea, quickly reported back to Washington that a "probable" full-scale attack was under way. Meanwhile, Syngman Rhee reacted to news of the invasion by ordering the imprisonment of more South Koreans. The UN was particularly upset about the North Korean invasion, because it had overseen the elections held in 1948, and did not want to see a war undo that election.