Friday, October 18, 2019
Relationship between GDP and the quality of life in Brazil Research Paper
Relationship between GDP and the quality of life in Brazil - Research Paper Example 81). Scope of Research The companies that are able to take the proactive mindset should have the capability to rebuild several business strategies with the objective of shaping a better future to taste success. The aim of the thesis is to devise a win-win situation that benefits the communities and the corporate bottom lines in a similar fashion. Thesis Statement What are implications of corporate involvement in order to solve social problems? Literature Review According to Dominic Barton, the operating environment of business is experiencing radical transformation. The going concerns are getting influenced by demographical, technological and societal factors. It can be anticipated that the above mentioned trends will affect the operating environment, but it is surprising to witness the confluence of the trends. He states a wave of transformation on the way. Elizabeth Stevenson sought to examine the size or the scope of the changes. The time calls for examination of whether the move is towards venturing into new markets, or ways to survive efficiently. The operating environment will be influenced in a different fashion if the move is towards overcoming the scarcity of resources or interacting with the authorities in a different way. According to Patrick Viguerie, examination of the demand pools will reveal that the revenue leaders of today will not be in a sustainable position in the coming years as far as unit leadership in emerging markets is concerned. This means that the new world will witness new leaders. He stated that companies opt to view the short term while deriving strategies. Several insertion points were put forwarded by Sven Smith. The strategies should be informed by some upfront section along with some trends that will contribute to promotion of new businesses. The section can be undertaken on a monthly or annual basis. Research is required to determine the degree of the position of the resources against the trends as well as to make a second st rategy if the undertaken strategy sinks (Belgard & Rayner, 2004, p. 4). The forecasted trends are easy to be embedded into the strategic planning processes but in a tricky fashion. A long term trend embedded into the planning process can be a throwaway in the initial stages. The existing challenge is to engage line executives in order to recognize the trends, and if the trends are analyzed as forces of nature, it would be hard to recalculate again into the trajectory of the business keeping in mind the subsequent shifts. The tasks ahead of the global corporation are to contend with the amount of restructuring and shifting of portfolios that are anticipated to occur in the coming decade. The corporations need to analyze the nature of the shifts and build a conviction and find the right moves that will contribute to the creation of value. The implications of the trends will be profound. The coming years will witness multiple headquarters as the organizations will like to expand their operations. The pools of talent that has been created around the world now are sufficient to deal with the expansion plans. A competitive advantage lies in bringing the talent pools into the leadership arrangements and assimilates them into the borderless corporations. In order to unleash the talent, the corporation will have to reengineer the society and the economy and provide
Thursday, October 17, 2019
Competitiveness in the International Electronics Industry Essay
Competitiveness in the International Electronics Industry - Essay Example The author Morri tells us that though the electronic industry is fairly small in the Dominican Republic by global standards, it employs however about 10,000 workers and contributes to about 5 percent of total Dominican exports (8). He further states that the electronic industry is by far the most important industry for a small economy (8). But in order to increase the competition in the electronic industry, the manufacturers in the electronic industry must learn to work together with the public sector to increase the competition position of the industry (Morri 9). The Dominican Republic has to meet the challenges of the public demands in order to ensure their competition in the electronics industry. The number of workers employed tells us how much is going into the export part of the trade. In order to accomplish competitiveness in the electronic industry, certain factors must be adhered to such as the "improvement in the quality and the cost of the electricity supply. Assistance with both local and international supply sourcing issues including possible common import purchasing and horizontal integration for inputs such as fabricated metals and moldings. In addition, the encouragement of domestic and foreign investment in critical local suppliers in such areas such as sheet metal fabrication, printed circuit boards, transformers, and general electronic component distribution (Morri 9)." In Latin America, there is extensive foreign investment in the sector by companies such as Verizon, Tricom, Centennial and Cable and Wireless and the cost of a T1 which is a high speed internet is the lowest priced in the whole of Latin America (Morri 16). On the other hand, "Guatemala, Honduras and Nicaragua have competitively low labor rates per hour, but they are not currently considered a competitive threat to the Dominican Republic because all three countries lack a secure environment (Morri 24)." In the above scenario, foreign investment in the Latin American companies makes it possible to guarantee low prices on certain commodities and labor being cheap makes it not a very feasible environment and so lacks the basis for a competitive environment. Another country that is ideal to examine would be the Chinese and Mexican market in relations to the US market. These two countries supply a lot of their goods to the US markets. According to Morri (9), China and Mexico supply a lot of their electronics to the US markets. In doing so, the global supply chain from the US to Asia threatens competition including low levels of linkages existing between the electronic manufacturers and the lack of industry expertise in the policy making and FDI promotion framework (Morri 10). The US markets are highly dependent on countries such as Mexico and China to provide a steady supply of electronic goods. Another important factor in increasing competition in the electronic industry is to : "create a one-stop-shop to streamline red tape. Increase image of electronics and the electrical industry locally. Also, employ or train electronic industry experts in policy and FDI promotion. In addition, build electronic industry support infrastructure for industry investors including offering investors full pre-, during- and post investment services and support. It would also help to decrease exit as well as entry barriers to increase investor confidence (Morri
Mental Health Laws in the movies PRimal Fear and Nuts Essay
Mental Health Laws in the movies PRimal Fear and Nuts - Essay Example In the case of ââ¬Å"Nutsâ⬠the defendant is declared to be mentally insane but seeks to establish that she is mentally competent to face trial. While these two films have a different orientation to the subject of legal insanity, both of them deal with the courtroom proceedings surrounding the establishment of this legal defense. In both these films, the defendants admit to their criminal acts, but it is the defense that puts forth the insanity plea in ââ¬Å"Primal Fearâ⬠, while it is the prosecution that advances the insanity defense in challenging the defendantââ¬â¢s competence to stand trial. The film ââ¬Å"Nutsâ⬠revolves around a call girl, Claudia, who has killed a client and has been declared to be insane by the resident jail psychiatrist. She comes from a respectable, middle class white family and her mother, a timid woman together with her stepfather, are eager to ensure that the psychiatristââ¬â¢s finding is substantiated, so that their daughter is declared not guilty and the publicity involved with a public trial can be avoided. As the film progresses, Claudiaââ¬â¢s hostile attitude which even extends to clipping her attorney on the nose, coupled with the huge chip she carries on her shoulder only appear to corroborate this diagnosis and make it even more difficult for Claudia to prove that she is mentally competent to stand trial for her crime. As the film unfolds, some of the characterââ¬â¢s motivation and reasons for her lifestyle and attitude become clearer, one of them being the revelation about her stepfatherââ¬â¢s abuse in childhood and h er motherââ¬â¢s tacit knowledge of the situation, while failing to address it. The film ends with Claudia successfully establishing her competence to stand trial, since her hostility and violent attitude is partly explained by her background. The film ââ¬Å"Primal Fearâ⬠presents a defendant who is a vulnerable looking altar boy, accused of
Wednesday, October 16, 2019
Competitiveness in the International Electronics Industry Essay
Competitiveness in the International Electronics Industry - Essay Example The author Morri tells us that though the electronic industry is fairly small in the Dominican Republic by global standards, it employs however about 10,000 workers and contributes to about 5 percent of total Dominican exports (8). He further states that the electronic industry is by far the most important industry for a small economy (8). But in order to increase the competition in the electronic industry, the manufacturers in the electronic industry must learn to work together with the public sector to increase the competition position of the industry (Morri 9). The Dominican Republic has to meet the challenges of the public demands in order to ensure their competition in the electronics industry. The number of workers employed tells us how much is going into the export part of the trade. In order to accomplish competitiveness in the electronic industry, certain factors must be adhered to such as the "improvement in the quality and the cost of the electricity supply. Assistance with both local and international supply sourcing issues including possible common import purchasing and horizontal integration for inputs such as fabricated metals and moldings. In addition, the encouragement of domestic and foreign investment in critical local suppliers in such areas such as sheet metal fabrication, printed circuit boards, transformers, and general electronic component distribution (Morri 9)." In Latin America, there is extensive foreign investment in the sector by companies such as Verizon, Tricom, Centennial and Cable and Wireless and the cost of a T1 which is a high speed internet is the lowest priced in the whole of Latin America (Morri 16). On the other hand, "Guatemala, Honduras and Nicaragua have competitively low labor rates per hour, but they are not currently considered a competitive threat to the Dominican Republic because all three countries lack a secure environment (Morri 24)." In the above scenario, foreign investment in the Latin American companies makes it possible to guarantee low prices on certain commodities and labor being cheap makes it not a very feasible environment and so lacks the basis for a competitive environment. Another country that is ideal to examine would be the Chinese and Mexican market in relations to the US market. These two countries supply a lot of their goods to the US markets. According to Morri (9), China and Mexico supply a lot of their electronics to the US markets. In doing so, the global supply chain from the US to Asia threatens competition including low levels of linkages existing between the electronic manufacturers and the lack of industry expertise in the policy making and FDI promotion framework (Morri 10). The US markets are highly dependent on countries such as Mexico and China to provide a steady supply of electronic goods. Another important factor in increasing competition in the electronic industry is to : "create a one-stop-shop to streamline red tape. Increase image of electronics and the electrical industry locally. Also, employ or train electronic industry experts in policy and FDI promotion. In addition, build electronic industry support infrastructure for industry investors including offering investors full pre-, during- and post investment services and support. It would also help to decrease exit as well as entry barriers to increase investor confidence (Morri
Tuesday, October 15, 2019
Overview on coral reef re-plantation in X-Sea port area Essay
Overview on coral reef re-plantation in X-Sea port area - Essay Example In many parts of the world, the coral population has undergone a massive reduction due to various human factors. The health of the coral reefs has been steadily declining over the past few decades. Environmental pollution and rampant destructive fishing practices damage the delicate corals. Nutrients seeping into the sea from agricultural areas cause the algae in the sea to increase in volume. This causes smothering of the corals and leads to decrease in size of coral reefs. Quite recently, the decrease in the coral populations has been attributed to a dozen or more deceases that attack corals. Many of these diseases were unknown until recently. Coral reefs have also been affected by bleaching. Bleaching is the discoloration or loss of symbiotic zooxanthellae. In 1979 and 1980, several incidents of coral bleaching occurred at reefs around Okinawa, Easter Island, northeast Australia, and the Caribbean Sea. Outbreaks of bleaching also occurred in 1982 and 1983, including reefs off east Africa, Indonesia, and the west coast of Central and South America, and from 1986 to 1988 in areas such as Taiwan, Hawaii, Fiji, Mayotte Island, and the entire length of the Great Barrier Reef. The most extensive bleaching episode ever documented occurred in 1998 and affected reefs in the Indian Ocean, Pacific Ocean, Red Sea, Persian Gulf, and Caribbean Sea. In some areas 100 percent of the corals were bleached and more than 70 percent of the corals died. (Smith 2003) Taking the rapidly declining coral population and the vulnerability of corals various measure are being taken in many countries to prevent further damage to the corals. Some of these steps include strict vigilance on fishing practices, artificial plantation of corals etc. Methods of coral community rehabilitation included coral transplantation and translocation, reattachment of coral fragments, providing artificial substrata, coral cultivation, prevention measures, and mitigation of damaged coral reefs. (Yeemin No
Health Services Organization Essay Example for Free
Health Services Organization Essay Identify and evaluate at least three forces that have affected the development of the health care system in the U. S. The U.S. healthcare system has continually evolved due to the success of innovative fore-thought. These innovations have been both strategic and tactical, influenced by all segments of the health care industry. There are many key strategic and tactical innovations, I will elaborate on three forces I feel affect the development of the healthcare system in the U.S.; they are: Increasing cost of healthcare, affect of economics on the healthcare system, and labor force trends in the U.S. as it relate to healthcare. * The steadily increasing cost of healthcare in the U.S. 1. The Unites States is known as the land of plenty, but if you are a native of this great nation you might feel quite differently about that statement. Being poor here has to be much like being poor anywhere else in the world, poor is poor; what might be different is opportunity. The opportunity that we are going to discuss is that of the pursuit of receiving the best healthcare regardless of race, creed, national origi n, or station in life (being with or without money). The cost of health care in the U.S. neared 2.6 trillion dollars in 2010, this is a staggering amount of money; but what make it more astonishing is that this amount is ten times higher than the 1980ââ¬â¢s sum of 256 billion dollars that was generated by health care system (population bulletin, 2008). The rate of funds generated by health care has slowed down in recent years, but still is expected to grow faster than the national income. Our country need to address this growing burden and not just let politician say itââ¬â¢s a major policy priority, really make it a priority for the overall good of our nation. Furthermore, the United States has been in a recession for most of the past decade, resulting in a high rate of unemployment and lower incomes for many Americans. These conditions have put even more attention on health spending due to its affordability. Since 2002, employer- sponsored health care coverage for employee and family premiums increased by 97%, making the pursuit of health care a burden on the workers and employers. Medicare covers disabled people as well as the elderly; while Medicaid provides medical coverage for low-income families. Medicare enrollment has grown tremendously over the years due to the aging baby boomers and Medicaid due to the recession. This has added considerably to government spending, straining both federal and state budgets. Health spending accounted for 17.9% of the nationââ¬â¢s Gross Domestic Product (GDP) in 2010 (kaiserEDU.com, Health Policy from the Henry J. Kaiser Family Foundation, Explained). * Economic affect healthcare. 2. Economics and health care is very simple to explain, especially by someone who has seen first-hand families being mentally tormented, because they could not afford dental care for their children, the check-up not covered by the companyââ¬â¢s insurance to enable your child to be eligible to play football, or not being able to afford the prescription medication. There are many reasons families go without medical care, and far too many times itââ¬â¢s just because the individual is living just above the poverty line; which make them ineligible for assistance. I personally feel the affect economics have on healthcare or the lack there of, can never be explained any clearer; unless you are experiencing it yourself. * Labor force trends in the U.S. 3. In the 1960ââ¬â¢s the U.S. labor force grow at the rate of 1.7 percent annually and continue to grow into the 70ââ¬â¢s as the baby boomer (those born between 1946-1964 generation continued to reach adulthood and enter the workforce. During this same period women began to enter the workforce as never seen before causing the labor force to grow at a rate of 2.6 percent annually. One might not see this as a health issue, but with women joining the workforce men began to feel the pressure, causing health complication. Women on the other hand who at one time lived the life of a care free house wife, but now working in corporate America; has started to feel stress now heart attacks are the number one killer of the American female species. I know there was nothing glamorous about being a slave, but slaves lived with just about no illnesses or life threatening diseases, know blacks have the highest numbers when it comes to diabetes, HIV, and high blood pressure than any other ethnic group (but we are free), freedom should make us take life more serious and take care of ourselves as well as our children. During the 1980ââ¬â¢s and 90ââ¬â¢s fewer people entered the workforce, therefore the labor force growth slowed down and ranged from 1.6 to 1.1 percent. Even though we had covered on set of baby boomers we were about to see another set reach adulthood and struggle for a place in the workplace (U.S. labor force trends), in-turn means no health insurance because they are no longer their parents dependent. Healthcare is becoming a great necessity due to infectious diseases, the year of the flower children seem to have spread more than just flowers. Health Insurance Companies are not seeing their usual capital gain at this point, consequently a change in the way benefits are paid across overall is about to change. At one time people thought as long as they paid their insurance premiums the benefits would be there when or if it was needed (we learned to read the fine print). * Speculate whether or not these forces will continue to affect the health care system in the U.S. over the next decade. (Include a force that was not mentioned that you believe will impact the health care system of the nation. Unfortunately we show no immediate signs that the cost of healthcare will decline in the Unites States anytime soon. With all the bickering about healthcare, thereââ¬â¢s one fact everyone seems to agree on: American medicine cost too much, especially considering what weââ¬â¢re getting for the money. As expert look toward the future, they donââ¬â¢t see the cost dropping dramatically anytime soon. Curbing the rise in healthcare cost depend on our ability to gain control of the many forces causing them to climb, technology has helped other industries lower costs by eliminating waste and increasing efficiencies, but its done the opposite in healthcare (Lisa Zamosky, Los Angeles Times, September 12, 2012. Without any dispute Iââ¬â¢m sure we can all agree the economy will always affect healthcare and the people who need it, which will always be everyone. We all hope the economy will make a rapid recovery, but thatââ¬â¢s just not how things work; just as it took decades of bad decisions to get us where we are today itââ¬â¢s going to take time for our nation to make a meaningful recovery. Over the next 50 years, the labor force is projected to grow even more slowly (at about 0.6 percent per year) as baby boomers retire. What will this mean as far as health care is concern; well as we grow older our need for healthcare on a regular base becomes more essential than it was when we were in our prime (population bulletin). Baby boomers, reaching senior living status promotes a different type of demand on the medical system; a tremendous demand for those employed by senior living facilities, as well as those providing home health care. * Evaluate the importance of technology in the health care system. Technology is the driving force behind the universe, if you are not a believer just think about the devices you use to get through your day; hence technology. Medical technology is constantly presenting us with new devices that make our lives more fulfilling, we have laser surgery, hip replacement, artificial limb to replace worn out or damaged ones, cataract surgery that have advanced so rapidly itââ¬â¢s amazing, can you believe a person can have heart surgery and be walking around the next day? This is all because of technology, itââ¬â¢s amazing. This is something we cannot put a price on, what is being learned and the advances being made due to research technology is saving lives as well as making lives better each and every day. References: KaiserEDU.com, Health Policy, from the Henry J. Kaiser family foundation, Explained, Cost and Spending. http://www.kaiseredu.org/en/Top ics/Costs-and-Spending Population Bulletin, Vol. 63 No. 2, June 2008, U.S. Labor Forces Trends By: Marlene A. Lee and Mark Mather (Marlene A. Lee is a senior research associate and editor of the Population Bulletin at the Population Reference Bureau. She holds degrees in public policy analysis and development sociology/demography from the University of North Carolina At Chapel Hill and Cornell University. Mark Mather is associate vice president of Domestic Programs at the Population Reference Bureau, where he coordinates several projects that communicate population research to advocacy groups, educators, the media, and the public. He holds a doctorate and a masterââ¬â¢s degree in sociology/demography from the University of Maryland. http://www.prb.org
Sunday, October 13, 2019
Sucrose Synthase Key Enzyme In Sucrose Metabolism Biology Essay
Sucrose Synthase Key Enzyme In Sucrose Metabolism Biology Essay Sucrose synthase is a key enzyme in sucrose metabolism. Sucrose metabolism is required by the plant to form carbon required for various processes in the plant such as respiration, starch and cell wall formation. The enzyme is encoded by a small multigene family where most plants have at least two isoforms of the enzyme. The kinetics of sucrose synthase show that different Km values and ratios of sucrose breakdown exist for the enzyme. The methods of extracting, assaying and purifying the enzyme are shown in the enzyme characteristics. Factors such as pH, addition of different buffers, metal ions, fungal volatiles as well as environmental factors such as anoxia have all been shown to affect sucrose synthase activity. The enzymes protein sequences have been phylogenetically divided up into six main groups using clustalw. Sucrose synthase is normally present in the cytoplasm but the availability of sucrose in the chloroplast and its ability to use ADP as a substrate would indicate that the enzyme may be able to act in the chloroplast as well as the cytoplasm. Sucrose synthase is an important enzyme in sucrose metabolism in plants cells. (Persia et al., 2008) The main route of entry of carbon from sucrose is commonly known to be sucrose synthase. (Bieniawska et al., 2007) This carbon is used for respiration and in the synthesis of cell wall polymers and starch. (Persia et al., 2008) The main form of reduced carbon in plants is sucrose. It is used to support growth and synthesis of reserve materials e.g. starch in heterotrophic sink tissues. (Matic et al., 2004) The UDP-glucose supplied by sucrose synthase is used for cell wall biosynthesis while working with the cellulose synthase complex. (Baud, Vaultier and Rochat, 2004) In most fruit tissues, an increase in sucrose synthase activity is alongside with sucrose accumulation. This would suggest that sucrose synthase plays a physiologically important role. (Islam, Matsui and Yoshida, 1996) Carbohydrates are transported from photosynthetic source tissues to sink tissues in the form of sucrose . The consequent cleavage of sucrose in the sink tissues is the first step for its use in various metabolic pathways. The sugar is cleaved in vivo by either sucrose synthase (Sus) or by invertase. Invertase catalyses an irreversible reaction where sucrose is cleaved into glucose and fructose (Matic et al., 2004) while sucrose synthase catalyses the reversible conversion of sucrose and uridine-diphosphate (UDP) into uridine-diphosphoglucose and fructose. (Hirose, Scofield and Terao, 2008) (Hardin and Huber, 2004) These enzymes play a crucial role in plant growth and development. (Abid et al., 2009) Sucrose Synthase is cytosolic (Ã
ebkovà ¡ et al., 1995) and has been characterized in many different plant species such as maize (Hardin and Huber, 2004), rice (Odegard, Liu and Lumen, 1996) and sugarcane (Schà ¤fer, Rohwer and Botha (2005)). Its activity has been studied in many plant organs such as roots, leaves and seeds. (Ã
ebkovà ¡ et al., 1995) For trees, cellulose biosynthesis is a highly regulated process in which carbon is permanently placed in their primary and secondary cell walls. Sucrose is the main carbon source for cellulose synthesis. The stem is made up of extremely active sink cells which utilise sucrose for cellulose synthesis. Sucrose synthase is the main sucrolytic enzyme in these cells that catalyzes the reversible conversion of sucrose into fructose and UDP-glucose which is needed for cellulose biosynthesis. (Joshi, Bhandari and Ranjan, 2004) It also plays an important role providing adequate sugar supply during anoxic stress. It has been shown that during anoxic germination of rice, sucrose synthase activity was enhanced whereas the activity of invertase was depressed. This would indicate that sucrose synthase is the enzyme predominantly responsible for sucrose breakdown during anoxia. (Joshi, Bhandari and Ranjan, 2004) Fig 1: Diagram of the cleavage and synthesis reaction of sucrose synthase (Rà ¶mer et al., 2004) Different isoforms of the gene are present in most plants. In the case of maize, two non-allelic genes were discovered for sucrose synthase but more investigation lead to the discovery of a third. At least three genes for sucrose synthase have been discovered in rice where the genes show differences in expression between tissues. RSus1 is expressed in root phloem while RSus2 is expressed in leaf phloem. (Schà ¤fer, Rohwer and Botha, 2005) When examining the different isoforms at an amino acid level it is appears that there is less homology between different sucrose synthase genes in a species than when the gene is compared to its corresponding gene in another species. In the case of maize, there is 75% homology between the SS1 gene and SS2 gene of maize but there is 90% homology between rice RSus1 and maize SS2 genes. In sugarcane, the SS1 gene is 97% identical at the amino acid level to maize SS1 gene. (Lingle and Dyer, 2001) Nolte and Koch (1993) undertook a study to determine whether sucrose synthase was localized to certain part of the vascular strand. It is well known that sucrose synthase is present in vascular bundles for example in transgenic tobacco plants phloem specific expression of a maize sucrose synthase gene has been observed. Their study, using immunohistochemistry, found that sucrose synthase was restricted to the cytoplasm of companion cells of the phloem and did not appear to be present in other organelles of the plant. (Nolte and Koch, 1993) The molecular mass of sucrose synthase can be determined by gel filtration. Sucrose synthase elutes from the column with a Kav value of 0.17844 which when using a calibration curve correlates to a molecular mass of 362kDa. Using SDS-PAGE gradient gel the molecular mass of each subunit can be estimated at 92kDa. This can conclude that sucrose synthase is a tetrameric enzyme with a molecular mass of 360kDa and four identical subunits of 90kDa. (Hardin and Huber, 2004) (Elling and Kula, 1993) It can associate with membranes and the actin cytoskeleton where its activity is known to be involved with cellulose synthesis. It does this by channelling uridine-diphosglucose to the growing glucan chain by the enzyme cellulose synthase. (Hardin and Huber, 2004) Analysis of Sucrose Synthase Gene Family: From the results of species examined to date, it is shown that sucrose synthase is encoded by a small multigene family. (Bieniawska et al, 2007) Most species of plants have at least two isoforms of sucrose synthase. These isoforms usually have comparable biochemical properties and highly homologous amino acid sequences. (Wen et al., 2010) Further analysis of transgenic and mutant crop plants show certain isoforms of sucrose synthase have specific functions in the plant. The rug4 mutation of pea removes the SUS1 isoform but has no effect on SUS2 or SUS3. This would indicate that these two isoforms are not able to make up for the loss of SUS1 in the seed or root nodule. It is clear that the loss of different isoforms affect the plant in certain ways. Loss of the SH1 isoform in maize has different outcomes from the loss of SUS1 isoform. SH1 is required for normal cell wall formation during endosperm development while both isoforms are needed for wild-type rates of starch synthesis. Why different isoforms have different functions is unclear. The same functions can be carried out in the cell by different isoforms but can occur in distinct cell types, developmental periods or environmental conditions. It is likely that different isoforms could have non-overlapping, particular functions in the same cell. (Bieniawska et al., 2007) It is difficult to decide on the precise roles of the genes in sucrose synthase gene family when there is not enough information in existence. Although there is some information available on some of the isoforms and theyre functions in the plant, no analysis of the functions of the gene family has been carried out. The model plant Arabidopsis is ideal for carrying out such an analysis. Six sucrose synthase genes are in the Arabidopsis genome. Based on comparisons of the amino acid sequences the isoforms they encode can be divided into three distinct pair groups. The isoforms SUS1 and SUS4 are 89% identical to each other but have less than 68% similar amino acid sequences to other isoforms. Similarly, SUS2 and SUS3 are 74% identical to other isoforms and are 67% less identical to the other forms of enzyme. SUS5 and SUS6 are 585 identical to each other but have less 48% similarity to the other isoforms. When examining other dicotyledonous species it appears that at least two of the thr ee pairs of isoforms are present. When phylogenetic analysis was carried out, it showed that the isoforms AtSUS1 and AtSUS4 are related to pairs of isoforms from pea (Fabacae), carrot (Umbelliferae) and potato (Solanacae). A pair of isoforms from Craterostigma plantagineum (Scrophulariacae) is closely related to the pair of isoforms AtSUS2 and AtSUS3 in the Arabidopsis. The pair AtSUS5 and AtSUS6 is related strongly to a pair of genes from rice. This evidence shows that it is unlikely that the three pairs of isoforms in Arabidopsis are as a result of gene duplication events. It is possible that each isoform has an exact function preserved in a wide range of plants. The members of Arabidopsis gene family are strongly differentially expressed in different organs of the plant through its development and in response to external stimuli e.g. environmental stress. This is seen in gene families of other plants studied. (Bieniawska et al., 2007) Fruit quality is determined by the type and quality of sugars present. A study of the sucrose synthase-encoding gene from the muskmelon fruit was carried out to evaluate how to genetically improve the quality of the fruit. This is done by finding the sugar components in fruit, to identify the enzymes involved in sugar metabolism and distinguish the relationship between sugar accumulation and the activities of related enzymes. It is thought that sucrose synthase is the enzyme involved in metabolising sucrose in developing muskmelon fruit. To examine this, a full length cDNA strand encoding sucrose synthase was extracted from a muskmelon fruit by RT-PCR and RACE and identified as CmSS1. Real time PCR analysis showed that CmSS1 expression changed in among different tissues of the plant e.g. root, stem, leaf. It showed that the mRNA levels are highest in the root and lowest in mature fruit. Fig 2: The patterns of CmSS1 transcript abundance in the different tissues of the muskmelon plant. These results were found using quantitative real-time PCR analysis of total RNA prepared from the root, stem, leaf, flower and mature fruit of muskmelon. During fruit development and ripening it was shown that CmSS1 mRNA was at its maximum level at five days after pollination and decreased steadily during fruit development until it reached its minimum level of maturity. This was discovered using again real-time RT-PCR analysis of mesocarp tissues from five days of pollination to ripening. Fig 3: This graph depicts the patterns of CmSS1 transcript abundance in developing muskmelon fruits found by using quantitative real-time PCR analysis of total RNA prepared from muskmelon. (Wen et al., 2010) The sugar content and SS activity were analysed to show the functions of CmSS1 in regulating fruit quality. It showed that very low concentrations of sucrose are present in young and unripe muskmelons. Between 20 and 30 days after pollination there is a massive rise in the amount of sucrose in the fruit. Sucrose synthase activity increased in the direction of sucrose synthesis and decreased in the direction of sucrose cleavage through fruit development. (Wen et al., 2010) Fig 4: The depiction of sucrose content and sucrose synthase activity during muskmelon fruit development. The first chart shows sucrose content during fruit development. The second shows sucrose activity in the sucrose synthesis direction and the third shows sucrose cleavage direction during muskmelon fruit development. (Wen et al., 2010) Enzyme Kinetics of Sucrose Synthase: An investigation was carried out by Schà ¶fer et al. to the find the properties of three sucrose synthase isoforms present in sugarcane. Kinetic analysis indicated that the three sucrose synthase genes in sugarcane are different isoforms, with major differences in Km values and the ratios of sucrose breakdown synthesis. The kinetic characteristics of the SuSyA and SuSyB isoforms, both expressed in the leaf roll, differ greatly. It was found that SuSyA has almost three times higher affinity for sucrose than the SuSyB isoform whereas SuSyB has a much greater affinity for UDP than SuSyA. Based on the differences in their kinetic properties it can be concluded that SuSyB and SuSyC are different isoforms of sucrose synthase. SuSyC has roughly ten times higher affinity for UDP compared to the other two isoforms. (Schà ¤fer et al., 2005) Fig 5: The graph shows the Lineweaver-Burk plot of 1/v against 1/S for the isoforms SuSys A, B and c where UDP was the variable substrate. The concentration of sucrose was kept constant at 320nM. The Km values were determined from the non-linear fit of the data to the Michaelis-Menten equation. (Schà ¤fer et al., 2005) When examining sucrose synthase in soybean nodules Morell and Copeland (1985) found the kinetic constants of UDP, UDPglucose, sucrose and fructose by fitting the data to the following two equations: 1. v = VA/KiaKh + KhA + KhB + AB 2. v = VA/Ka + A + A/Ki The kinetic constants for ADP, CDP and ADPglucose were found using non linear regression analysis of initial velocity data. Fig 6: Graph showing the effect of sucrose concentration on the cleavage activity of sucrose synthase in soybean nodule. The lines show the fit of data to equation 1. The reaction mixture were composed of 20à µmol Hepes-KOH buffer (pH 7.5) 2à µmol UDP, 1.5à µmol NAD, 25à µg UDPglucose dehydrogenase. Each symbol represents a different concentration of sucrose. The dark circle shows 3.2à µM, the clear circle shows 4à µM, the dark triangle shows 6.25à µM, 10à µM is shown by the clear triangle and the dark square depicts 20à µM. In the cleavage and synthesis direction standard Michaelis-Menten kinetics are observed. The variation of concentration of sucrose at different concentrations of UDP gave an intersecting pattern of linear double reciprocal plots. (Morrell and Copeland, 1985) Parameter Value V (U/mg protein) 13.3à ±2.0 Km sucrose (mM) 31.3à ±7.1 Ki sucrose (mM) 31.9à ±13.1 Km UDP (mM) 0.005à ±0.002 Ki UDP (mM) 0.005à ±0.001 Fig 7: Table showing the kinetic parameters for the cleavage reaction of sucrose synthase in soybean nodules. (Morrell and Copeland, 1985) Fig 8: The graph depicting the effect of UDPglucose concentration on the synthesis reaction of sucrose synthase activity in soybean nodules. The reaction mixtures contained 20à µmol Hepes-KOH buffer, 15 à µmol fructose, 5à µmol MgCl2, 0.4 à µmol P-enolpyruvate, 0.15 à µmol NADH, 20à µmol KCl, 25à µg pyruvate kinase 25à µg lactate dehydrogenase and the required amount of enzyme. As in the previous graph, the amount of UDPglucose was varied in the presence of 2.5mM (dark circle), 3.2mM (clear circle), 4mM (dark triangle), 5mM (clear triangle) and 8mM (dark square) fructose. The results on the graph are representing the fit of data to equation 1. When the concentration of UDPglucose was varied at the concentrations of fructose in the graph, an intersecting pattern of linear double reciprocal plots was seen. From fitting the data from the graph to equation 1, it is noted that substrate inhibition would have occurred at a concentration greater than 15mM fructose. Parameter Value V (U/mg protein) 14.3à ±1.2 Km fructose (mM) 3.7à ±0.8 Ki fructose (mM) 19.6à ±9.9 Km UDPglucose (mM) 0.012à ±0.006 Ki UDPglucose (mM) 0.064à ±0.014 Fig 9: table showing the kinetic results by fitting the figures from the graph to equation 1. When partially purified SuSyA, SuSyB and SuSyC were blotted to a nitrocellulose filter the results showed that all three isoforms are approximately 94kDa. (Schà ¤fer et al., 2005) The would correlate to the findings of Hardin et al and Lothar et al who stated that sucrose synthase is tetrameric enzyme made up of four 90kDa subunits. Fig 10: Immunoblot of sugarcane SuSy. A crude extract of protein from leaf roll was loaded into lane 2 while partially purified isoforms of SuSyA, SuSyB and SuSyC were loaded to lane 3, 4 and 5. The molecular weight ladder was used to identify the bands see in each lane. (Schà ¤fer et al., 2005) Characteristics of Sucrose Synthase: Extraction of Protein: The method for extracting protein from the leaves of maize (Zea mays), rice (Oryza sativa) and tobacco was done as follows: 1-3g of leaves was ground in liquid nitrogen and the powder was mixed in the ratio 1:2 with extraction buffer. The buffer was made up of 0.1M tris-HCl, pH 8, 10mM DTT and 1% polyvinylpolypyrrolidone. The samples were then incubated on ice for 15 minutes and then centrifuged at 1,000g for 10 minutes at 4oC. The pellet was then removed and the supernatant was re centrifuged at 100,000g for one hour at 4oC. After this final centrifugation, the pellet and supernatant which contained the soluble proteins was resuspended in sample buffer for electrophoresis. (Persia et al., 2008) When extracting protein from rice seeds, a similar procedure is followed. Seeds weighing roughly 50-100mg at various stages of growth were homogenized in 400à µl of extraction buffer and kept at 4oC. The buffer was made up of 50mM Tris-HCl, pH7.5, 1.0mM DTT, 1.0mM EDTA and 2mM PMSF. Ammonium sulphate fractions (30-50% w/v) were precipitated and then resuspended in dialysis buffer made up of 50mM Tris-HCl, pH 8.0, 5mM MgSO4, 5mM 2-mercaptoethanol. This was then dialyzed overnight at 4oC. (Odegard, Liu and De Lumen., 1996) The method for extracting protein from tobacco pollen tubes is slightly different to those mentioned previously. The pollen first was slowly thawed from storage at -20oC and hydrated in a humid chamber overnight. It was then germinated in BK medium and allowed to germinate at 25oC for three hours. After this period had elapsed, the pollen was collected by centrifugation at 1,000g for 5 minutes at 25oC. It was then washed twice with BRB25 buffer which is made up of 25mM HEPES, pH 7.5, 2mM EGTA and 2mM MgCl2 and 15% Suc. After washing, the pollen was resuspended in lysis buffer and lysed on ice using a motor-driven Potter-Elvehk-jem homogenizer. The lysis buffer used was made up of BRB25 buffer along with 2mM dithiothreitol, 1mM phenylmethylsulfonyl fluo ride (PMSF), 10à µL/mL protease inhibitors, 1mM NaN3 and 10% mannitol. After lysis was carried out, the samples were centrifuged at 1,000g for 10 minutes at 4oC. The supernatant was centrifuged again at 4oC for 45 minutes at 100,000g over a 20% (w/v) Suc cushion. The supernatant was then collected as it contained the soluble protein fraction. (Persia et al., 2008) Enzyme Assays: After extracting protein, the sucrose synthase activity in sugarbeets was found using a spectrophotometric end point assay. The activity of the enzyme was monitored as fructose formed at 35oC. This was carried out in a solution that contained 250mM sucrose, 2mM UDP and 100mM MES. The control was carried out by assaying for activity in the absence of UDP. The total protein concentration was determined using the Bradford method where bovine serum albumin was the standard. (Klotz and Haagenson., 2008) When assaying for protein from rice, the Bradford method was followed to determine protein concentration as was done in Klotz et al. 40mg of protein was used per assay. The assay was carried out in 20mM MES pH 6.4, 200mM sucrose and 4mM UDP for 15 minutes at 30oC. The reaction was stopped by boiling for 2 minutes and the fructose levels were measured. The control tubes did not contain UDP. (Odegard, Liu and De Lumen., 1996) When examining the effect of sucrose synthase on carbon partitioni ng a similar method was followed for assaying the protein. Sucrose synthase was assayed in the direction of sucrose breakdown using 50à µl poplar plant extract. The tetrazolium blue assay was followed to determine the amount of free fructose. As in previously mentioned assays, the absence of UDP in the assay acted as a control. The total protein content was found by employing the Bradford (Bio-Rad) protein assay. (Coleman, Yan and Mansfield., 2009) A similar method was followed for carrying out an assay for the enzyme on tomato tissue. The reaction mixtures contained 50mM Hepes-NaOH buffer, 15mM MgCl2, 25mM fructose and 25mM UDP glucose. This was incubated at 37oC for 30 minutes and was terminated with the addition of 70à µl of 30% KOH. The enzyme blanks were terminated with the addition of KOH at 0 minutes. The tubes were then kept at 100oC for 10 minutes to destroy any fructose. The soluble protein content was determined using the Lowry method whereby bovine serum albumin was th e standard. (Islam, Matsui and Yoshida., 1996) Alkaline copper solution is added to each tube and allowed to stand at room temperature for roughly 30 minutes. Dilute folate reagent is then added to each tube rapidly and after 30 minutes the absorbance is read at 750nm. (Lowry et al., 1951) The results were measured as à µmole of sucrose per minute per mg protein. (Islam et al., 1996) When assaying for sucrose synthase in the cleavage direction Rà ¶mer et al used recombinant SuSy1 gene from potato. In a volume of 100à µl HEPES buffer with a concentration of 200mM and pH 7.6 recombinant sucrose synthase was incubated along with 2mM UDP and 500mM sucrose for ten minutes at 30oC. HPLC analysis was used for the formulation of UDP-glucose. The Bradford assay was used to determine protein concentrations as was carried out by Klotz et al and Coleman et al. The activity of the enzyme was also tested with the nucleoside diphosphates dTDP, CDP, ADP and GDP at 2mM. For assaying recombinant e nzyme in the synthesis direction a similar method was followed as when assaying for standard enzyme. Recombinant sucrose synthase was incubated in a total volume of 100à µl HEPES buffer where this time the pH was 8.0 and the concentration was as in cleavage direction of 200mM. 1mM UDP-Glc and 20mM D-fructose was also added to the mixture and it was incubated for five minutes at 30oC. The reaction was heated to 95oC for five minutes and HPLC analysis was used to establish the formation of UDP. The sucrose synthase activity was also tested using dTDP-Glc, CDP-Glc and ADP-Glc. (Rà ¶mer et al., 2004) Purification of Protein: After extraction of the protein from the crude extract, purification can be carried out. This can be done in a number of ways such as Batch adsorption with Sephadex A50, Anion exchange chromatography and Gelfiltration. SDS-PAGE can be carried out after purification to check the purity of the protein sample. The Sephadex A50 gel is loaded into a glass funnel and washed twice with deionised water. The gel was then washed twice with 300ml standard buffer. The protein sample was loaded to the gel and slowly sucked through the gel for 30 minutes. The gel bed was then washed with 300ml standard buffer and then with 300ml standard buffer containing 100mM KCl. The last washing step contained 300mM KCl. 200ml of the first salt preparation was concentrated to 40-50ml by using a cross-flow ultrafiltration module with YM 30 ultrafiltration membrane that had been pretreated with 55 PEG 4000 solution. This was done to prevent the enzyme sticking to the membrane. In anion exchange chromatography a Sepharose Q column was first equilibrated with 300ml Hepes buffer. This was made up of 200mM pH 8 with 50mM KCl. 70-80mg of protein sample was loaded and the elution was started using two different salt gradients. To prevent enzyme inactivation after elution all the fractions were titrated back to pH 7.2. All fractions that contained enzyme activity were pooled and concentrated by using ultrafiltration. Gelfiltration experiments are carried out on a prepacked HiLoad 16/60 Superdex 200 prep grade column that was connected to FPLC equipment. Four samples containing 2mg of protein were loaded and eluted with a flow rate of 1 ml min-1. The fractions were then pooled and stored at -20oC in 500à µl aliquots. (Elling and Kula., 1993) To determine the purity of the protein, SDS-PAGE is carried out. This is done by loading 100à µg of protein samples to a 125 SDS-polyacrylamide slab gel that was overlaid with stacking gel. The electrophoresis was carried out at 4oC and at 40V for 16 hours a nd followed by 200V for one hour. Coomassie blue R 250 was used to stain the gel followed by destaining. (Kumutha et al., 2008) Factors that affect Sucrose Synthase Activity: Ã
ebkovà ¡ et al (1995) stated that sucrose synthase has two different pHs for optimal activity. In the cleavage direction it was found that most enzyme activity was observed between pH 6.0 and 8.5 at temperatures between 50 to 55oC. In the synthesis direction, a pH between 8.5 to 9.5 and a temperature of 35oC was optimal for enzyme activity. (Ã
ebkovà ¡ et al., 1995) This would correlate with the findings of Morell and Copeland (1985) who found that optimal activity of the enzyme in soybean was at pH 6 in the cleavage direction and at a pH of 9.5, sucrose synthase activity in the synthesis direction was at its highest. It was also found that at a pH of 7.5 the cleavage and synthesis activities were their highest. (Morrell and Copeland., 1985) Elling and Kula (1995) examined the effect of buffers TES-NaOH, MOPS-NaOH, TEA-NaOH and Tris-HCl on the pH optimum of sucrose synthase activity. These were determined using UDP and TDP as substrates for the reaction. They found that the e nzyme had its highest activity in Hepes-NaOH buffer. When MOPS-NaOH and TES-NaOH buffer was used, only 60-80% activity was noted. (Elling and Kula 1995) It was also found that the velocity of the reaction could be increased by increasing the temperature where optimal activity was seen between 50 and 60oC. Xu at al (1989) reported that potato and bean are also able to withstand these high temperatures. However once the temperature goes above 60oC enzyme activity starts to decreased rapidly and was destroyed once the temperature reached 70oC. (Xu et al., 1989) The cleavage of sucrose by the sucrose synthase enzyme was investigated to find the rate of cleavage reaction using different nucleosidediphosphates as cosubstrates. They found that the rate of reaction was UDP>TDP>ADP>CDP>GDP. Echt and Chourey (1985) found similar results when examining nucleotide specificity. They found that substrate specificity for SS1 and SS2 were UDP>TDP>ADP>CDP>UTP where each substrate was at a concentrat ion of 4mM. (Echt and Chourey 1985) Low levels of heavy metal ions such as mercurate inhibited cleavage activity of the enzyme. This would lead to the assumption that sulfhydryl groups are involved in the catalytic process. It is also inhibited by Tris-HCl and by small concentrations of MgCl2 and MnCl2. (Ã
ebkovà ¡ et al., 1995) Cations were shown by Elling and Kula (1995) to have a slight influence on enzyme activity. The activity was lessened slightly (10%) by the presence of 1mM Mn2+ and Mg2+ ions with UDP. The enzyme is completely inactivated in the presence of 1mM Cu2+ or Fe2+. (Elling and Kula., 1993) A recent study was undertaken to examine the effects of volatile emissions on carbohydrate metabolism. Studies on this area have taken place before but it is usually examining the results of physical contact between the host plant and the microbe. No work has taken place until now on the effect on the plant in the absence of physical contact. Many microbes such as Pseudomonas spp, Strepomyces spp, Penicillin spp and a selection of truffles produce ethylene. This gaseous plant hormone plays an important role in many aspects of plant growth and development such as seed germination, root hair initiation, fruit ripening and starch accumulation. In the work of Ezquer et al (2010), the possible effects of volatiles released from gram-negative bacteria, gram-positive bacteria and fungi on starch metabolism was studied. The results showed that the volatile compounds released by microbes promoted high levels of starch accumulation in mono- and dicotyledonous plants. It also revealed fungal vo latiles (FVs) promoted massive changes in expression of genes involved in many important processes in plant such as metabolism of carbohydrates, amino acids, sulphur and lipids, energy production, protein translation and stability, cell wall biosynthesis and photosynthesis. However no changes were noted in the expression in some of the genes that coded for proteins involved in starch and sucrose metabolism such as plastidial hexokinase, plastidial phosphoglucose isomerase, plastidial adenylate kinase, alkaline invertase and UDPglucose (UDPG) pyrophosphorylase. It was found in the study that FVs strongly upregulate the expression of Sucrose Synthase in potato leaves. The plants were cultured in the presence and absence of FVs emitted by A. Alternata. This caused a massive enhancement of expression of Sus4 isoform. A 29.4- and 31.63-fold increase was observed in expression when the plants were cultured in the presence and absence of sucrose. This isoform of the enzyme controls the accumulation of ADPG, UDPG and starch in potato source leaves and tubers. Analyses of the intracellular amounts of starch and nucleotide-sugars in the leaves of the plant show a positive correlation between patterns of enzyme activity and starch, UDPG and ADPG amounts. This was noted when the leaves were cultured in the presence and absence of FVs. Western blot analyses and quantitative RT-PCR confirmed also the increase in expression. (Xu et al., 1989) Environmental Factors affecting Sucrose Synthase Activity: Anoxia: Waterlogging is where oxygen supply is blocked to root leading a severe decrease in the amount of oxygen available to the plant. This leads to inhibition of root respiration that causes a major decline in energy of root cells affecting vital metabolic processes of the plant. This is restriction of oxygen supply is known as anoxia. The presence of glucose in an anoxic incubation medium drastically decreases meristem death and studies have shown that sucrose synthase is the enzyme mainly responsible for sucrose breakdown under anoxia. (Kumutha et al., 2008) The increase in glycolytic demands caused by these demands is the cause of increased sucrose synthase expression. This has been demonstrated in many plant species e.g. sucrose synthase gene is induced in wheat and in rice when oxygen levels are low. (Ricard et al., 1998) Harada et al (2005) also found an increase in sucrose synthase activity in pondweed turins while under anoxia. (Harada et al., 2005) Klotz and Haagenson (2008) foun d that sugarbeet contained two genes for sucrose synthase activity-SBSS1 and SBSS2. They demonstrated that anaerobic conditions caused a large increase in the transcription levels of SBSS1 and a quick increase and succeeding decline in SBSS2 transcription levels. However this did not correlate with a significant increase in sucrose synthase enzyme activity. A 23% increase in sucrose synthase activity was noted after initiation of anaerobic conditions but otherwise the activity of the enzyme did not differ greatly to that of the controls. (Klotz and Haagenson., 2008) Fig 11: The graph outlines the different rates of sucrose synthase activity in the con
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