Bahlawane discussion Essay Example for Free

Bahlawane discussion Essay Conclusion Taking in account the scheme of galactoglucan synthesis regulation (Fig. 4. 1) and the scheme of motility regulation (Fig. 4. 2) proposed in this study, we may try to follow the effect of such regulation paths in the life styles of the bacteria. The last one is named as free – living microorganism or as symbiont in the plant root. In the first case, the bacteria are exposed to dryness and nutrients starvation. At this stage, the biofilm production is a pre-requisite for survival. Therefore, the EPS’s biosynthesis has to be switched ON. As it is quite improbable that the cell density is high enough to activate the quorum sensing system, we can speculate that MucR plays a key role in activating the succinoglycan biosynthesis. Since the soil exhibits very low level of Pi, galactoglucan is, at this point produced through the activation via phoB and WggR. Upon biofilm formation, the cell density probably increases and could activate the quorum sensing system, allowing the bacteria to produce more galactoglucan and swarm towards better conditions. In such conformation, the cells present within the centre of the swarming population are non motile and synthesized EPS; thus the cells present at the migration front are highly motile but do not synthesized EPS. It would be interesting to clarify whether a cell differentiation, as proposed by Soto (Soto et al. , 2002), takes place at this stage. Finally, if the host is present in the next neighbourhood the chemotactic compounds, as well as the nutrients found in the rood exudates, will attract the bacteria. When approaching the root, the moisture increases, along with the nutrients availability; so that swarming motility will be replaced by swimming motility that decline progressively. Indeed, the bacteria attached to the root, increasing the cell density that may lead to the inhibition of flagella production via ExpR / QS. Instead, EPS are produced, allowing recognition between the plant and the microbe as well as the invasion of the new synthesized infection thread. Once within the root, the bacteria will differentiate to bacteroid and start fixing nitrogen. We tried to highlight in this thesis the relevance of exopolysaccharides and motility for an efficient symbiosis. Great advances have been made the last years, leading to the identification of the quorum sensing interaction with motility. We participate in inclusion of MucR, as new regulator of motility and ExpR as requisite for swarming. However, the full understanding of the influence of motility in symbiosis establishment will require finding out which signals are inducing mucR and exoR/ exoS. Moreover, some tests have to be implemented to investigate the symbiosis establishment in more realistic conditions. Indeed, the bacteria are usually directly inoculated to the root, so that motility, via swarming or swimming is not required. Acknowledgments First and foremost, I would like to thank Prof. Dr. Alfred Puhler, Chair of the Genetics department, for allowing me use the very good infrastructure that promotes a very pleasant and conducive atmosphere during my research using performant techniques. I am especially grateful to Prof. Dr. Anke Becker, my supervisor, for giving me the chance to come back to research. Without her advices, ideas and resources, this work would not be possible and achieved. Thus, I thank her too for the freedom she gave me, as well as her support to test new ideas and her great help by conceiving and writing the manuscripts that become the pillars of this manuscript. Within the laboratory members, I would like to thank first Dr. Birgit Baumgarth who introduced me to the lab and to the investigated organism. Then, special thanks to Dr.Matthew McIntosh for the quorum sensing – related work and his help for preparing the derived publication. Furthermore, I would like to deeply thank Dr. Natasha Pobigaylo for her friendship, her helpful discussions and for giving me courage when I am about to lose it. I thank Manuela Mayer, too, for the assistance in microarray hybridizations as well as Dr. Lisa Krol, Javier Serrania and Thomas Montfort for the everyday help in the lab. Finally, I would like to thank all Exopol group members for the support and advices. Least, I would like to thank my family for their unending and heartwarming support in many ways. Special thanks to Rachida Bendaou, my mother-in-law, for her support in caring my children during my research. I would like to thank my children, Ines, Soraya and Jasmine, for filling up my life with love and happiness. I would like to apologize for the bad mood and stress situations that are unfortunately connected with such a thesis. My heartfelt gratitude to my understanding and loving husband, Naoufal, for his moral and financial support, for believing in me and for sharing the passion for science with me. Resume In order to enter symbiosis with its legume partner, Sinorhizobium meliloti has to face continual changing conditions. It has more ability to adapt quickly to the situation than the ability to face it efficiently that makes the difference in term of symbiosis efficiency. For the first interactions with its host, motility is required by S. meliloti to move towards the chemotactic compounds released by its host when exopolysaccharides (EPSs) are required later on, for the attachment to the root as well as for the invasion of the infection thread, leading to the formation of the root nodule. We focused in this study the regulatory networks leading to the coordination of motility and EPS’s production in the strain Rm2011. Depending on the phosphate concentration encountered in the environment Rm2011 synthesizes two different exopolysaccharides (EPS). Galactoglucan (EPS II) is produced under phosphate starvation but also in the presence of extra copies of the transcriptional regulator WggR (ExpG) or as a consequence of a mutation in mucR. The galactoglucan biosynthesis gene cluster contains the operons wga (expA), wge (expE), wgd (expD), and wggR (expG). Two promoters, differentially controlled by WggR, PhoB, and MucR, were identified upstream of each of these operons. The proximal promoters of the wga, wge, and wgd transcription units were constitutively active when separated from the upstream regulatory sequences. Promoter activity studies and the positions of predicted PhoB and WggR binding sites suggested that the proximal promoters are cooperatively induced by PhoB and WggR. MucR was shown to strongly inhibit the distal promoters and bound to the DNA in the vicinity of the distal transcription start sites. An additional inhibitory effect on the distal promoter of the structural galactoglucan biosynthesis genes was identified as a new feature of WggR in a mucR mutant. Motility is organized in S. meliloti in a hierarchical cascade, with Class Ia genes, encoding the major regulator of motility VisNR; controlling the expression of the class Ib gene, rem, which encodes a central regulator, activating the expression of the downstream Class II and class III genes. We could demonstrate that MucR binds a DNA sequence upstream of rem, following a different mechanism as previously observed upon binding upstream of the wg genes. By this way, MucR inhibits rem expression as well as the expression of the Rem-regulated genes such as flaF and flgG. Furthermore, we addressed a balance of the swimming and swarming abilities of several S. meliloti strains derivatives of Rm2011. We could show that all strains, able to build flagella, were swimming on low viscosity agar plates. However, swarming over high viscosity agar plates required all a functional expR / sin locus, the ability to build flagellum and the production of exopolysaccharides. Finally, we propose a model for the coordination of motility and EPSs synthesis in S. meliloti.

Bioerosion and Reef Ecology Essay example -- Bioeroding Ecosystem Ecol

Bioerosion and Reef Ecology The breakdown of calcareous substrates among coral reefs, or bioerosion, is a facet of reef ecology too often forgotten. The process plays a much more important role than it is usually credited with. Bioeroding species, consisting of many different types of organisms that act on the environment in a seemingly endless variety of ways, interact with the ecosystem and with each other as part of the reef growth and degradation cycle. The degradation portion of this cycle, the part that is most often overlooked, is essential for the development of reefs as the diverse and beautiful habitats that we know them as. Bioerosive interactions are very complex, and a general understanding of the process of bioerosion is necessary to gain a solid understanding of the reef ecosystem. Introduction What is the significance, if any, of bioerosion in respect to a reef’s ecosystem? How does bioerosion take place, and what effects does it have on the biology of a reef? These are important questions to ask, as the processes that take place inside dead coral skeletons or over long periods of time generally happen beyond the perception of the human eye or mind, and thus are often looked over. Bioerosion, defined for this paper as the biological breakdown of substrates (specifically the calcareous skeletons of corals and other reef organisms), is half of the process of reef growth and decay and is too often looked upon as a negative force in reef dynamics. Not only is bioerosion the occasional victim of a generally negative sentiment, but bioerosion is sometimes simply forgotten from scientific literature. For example, Australia’s Great Barrier Reef attributes the whole of physical breakdown of dead coral skeleton... ...-604. LeCampion-Alsumard, T., Golubic, S., Hutchings, P. (1995). Microbial endoliths in skeletons of live and dead corals: Porites lobata (Moorea, French Polynesia). Marine Ecology. Progress Series 11, 149-157. Naylor, L.A., Viles, H. A., and Carter, N.E.A. (2002). Biogeomorphology revisited: looking towards the future. Geomorphology. Volume 47. Issue 1. pp. 3-14. Rouse, Greg W., and Fredrik Pleijel. (2001). Polychaetes. Oxford University Press, Inc. New York. Spencer, T., and Viles, H. (2002). Bioconstruction, bioerosion, and disturbance on tropical coasts: coral reefs and rocky limestone shores. Geomorphology. Volume 48. Issues 1-3. pp. 23-50. Zubia, M. and M. Peyrot-Clausade. (2001). Internal bioerosion of Acropora formosa in Reunion (Indian Ocean): microborer and macroborer activities. Oceanologica Acta. Vol. 24, Issue 3. pp. 251-262.

Ncell

Methodology We surveyed much more about t Ncell through the use of various sources. Through these surveys we came to know about different aspects about Ncell. But we tried to get more insight of the consumers or the users of Ncell . With this prime motives we all decided to conduct a small Consumer Feedback Survey among the users of Ncell. We asked them the close ended questionnaire as a part of our primary survey . These questionnaire were distributed among the 20 Ncell users To know the diversified customers response we have selected the respondents from many sector llike professionals, Students , housewife and so on.The nature of our questionare were solely based on the satisfaction level,attitude towards product ,features of products. The sample of the questionnaire is presented below: Customer Feedback Survey-Questionnaire Name: Address: Contact: Email: Profession: Please tick the appropriate options Q. 1. What is your view on network quality of Ncell ? a) Excellent b)Good c)Ave rage d)Below Average Q. 2. Which service of Ncell do you use most? a)Call b) GPRS/3G c)Data card d)others Q. How expensive do you think is the price of Ncell service? a)Cheap b)Satisfactory c)Expensive d)Comparatively expensive Q. 4 How much money ( in average )do you spend in Ncell ? a)less then 100 b)R. S 100-250 C)R. S 250- 500 d)R. S 500 and above Q. 5 How does the feedback and customer care service respond to your problems ? a)Very Fast b)Average C)Satisfactory d)Slow response Q. 6 How is Advertising of Ncell? a) Persuasive b) Reinforcing c) Reminding d) Informative Q. How often do you get bonus scheme or offer from Ncell ? a) Frequently b) Very often c) Sometimes d) Rarely Q. 8 If you are using Ncell Internet service, how is it? a) Very fast b) comparatively fast c) Moderate d) slow Q. 9 What factor influenced you to purchase Ncell service? a) Media advertisement b) Hoarding board c) word of mouth d) References e) Non Q. 10 Do you have any suggestions that would help us to imp rove our Ncell service? Signature of the customer: Thank you for your kind cooperationMajor Findings From the customer survey that we conducted with 20 different Ncell customers we have found some crucial results. According to them the network quality of Ncell service is good however some of them said it is excelled. Likewise talking about the services provided by Ncell many of them are using call and GPRS service, the majority of GPRS users are youth among them. Another important result we have found about the price that Most of the respondent said it is comparatively expensive (which mean the Ncell Price is expensive than its major rival NTC).However the service within the Ncell subscriber is not that expensive. The major factors affecting to purchase of Ncel Service are Media advertisement, hoarding board, word of mouth and references respectively. Moreover the advertising of the Ncell is more reinforcing according to the respondents however some of them said it is informative e also. Considering the aforementioned survey discussion now we would like to show here some figures and chart to understand the findings in more specific way. 1. Quality of Network

The Industrial Revolution - 936 Words

Nobel Prize laureate and economist Robert Emerson Lucas wrote in regards to the Industrial revolution: For the first time in history, the living standards of the masses of ordinary people have begun to undergo sustained growth. The novelty of the discovery that a human society has this potential for generating sustained improvement in the material aspects of the lives of all its members, not just the ruling elite, cannot be overstressed.† (Lucas 2002). The revolution itself was centred in Britain before spreading to the rest of Europe and America, and is most commonly placed within a general time period of the 18th to 19th century, though it is commonly accepted that it begun in approximately 1760 AD, and ended in 1830 AD (Ashton 1997). The Industrial Revolution was characterised by Britain’s transformation from an agrarian society, to one of manufacturing, rapid urbanisation, mass production, globalising markets, transport and communication developments, and most significantly- constantly increasing technological advances unlike any other point in history (Mokyr 1990). Employment opportunities were different to ever before, as factories, mills, mines, and positions in development became available (Miller Dodd 2014). Whilst industrialisation paved the way for some of the most significant advances in human history, it is also important to consider the impact it had upon the society in terms of what were often poor living and working conditions. B A C K G R O U N D /Show MoreRelatedIndustrial Of The Industrial Revolution1666 Words   |  7 PagesMartinez English IV, 1st hour 4/29/16 The Industrial Revolution The Industrial Revolution set people away from farms and small villages and moved them to cities and towns because of the job opportunities that arose in the cities. The Industrial Revolution not only helped people move along in the late 1700s and early 1800s but also it has made the people what they are today. During the Industrial Revolution, the movement from an agrarian society to an industrial one reshaped the roles of families, widenRead MoreThe Revolution Of The Industrial Revolution917 Words   |  4 PagesWhen thinking of the industrial revolution, I usually correlate this transitional period to great advancements in machinery, and an increase in jobs. However, after looking past the surface of the industrial revolution, in regards to the promise of great wealth, this promise was not kept, along with other issues. I believe that a â€Å"better life† would mean that people would not have to go through the same struggles they once did before the revolution, struggles such as not having a job, money, homeRead MoreThe Industrial Revolution943 Words   |  4 PagesThe Industrial Revolution, a Revolution that began in Britain in the nineteenth century, saw people move from working in the farming industry to working in factories. This transition from an agrarian society meant that many people moved to cities in search of jobs. New methods of manufacturing allowed goods to be produced far more cheaply and quickly than before. However, the Revolution came with its own negative consequences. The lives of children during the Industrial Revolution were torturousRead MoreThe Industrial Revolution1633 Words   |  7 Pagesmeans of communication, factories to manufacture the products you need, places to work, and ways to travel and transport goods. And what made these possible? The answer is the Industrial Revolution, which started in Europe around the year 1730. A revolution is a major change or turning point in something. The Industrial Revolution was a major turning point in history and in the way people lived. Their careers, living situations, location, values, and daily routines all changed, and they needed it desperatelyRead MoreThe Industrial Revolution1097 Words   |  5 PagesBefore the advent of the Industrial Revolution, most people resided in small, rural communities where their daily existences revolved around farming. Life for the average person was difficult, as incomes were meager, and malnourishment and disease were common. People produced the bulk of their own food, clothing, furniture and tools. Most manufacturing was done in homes or small, rural shops, using hand tools or simple machines. Did You Know? The word luddite refers to a person who is opposedRead MoreThe Industrial Revolution1090 Words   |  5 PagesShort Term Misery†¦ Long Term Gain There are two major industrializations that have occurred through out history, both which began in England. The Industrial Revolution was from 1750 until 1800. The first and second industrialization were filled with many inventions, new societal ideas, new raw materials, new sources of power, also new ideas and societal implements were made enabling the world and society to evolve. Overall these industrialization was filled with death, neglect, and disease but endedRead MoreThe Industrial Revolution705 Words   |  3 PagesThe Industrial Revolution was the quintessence of capitalistic ideals; it bred controversy that led to Karl Marx’s idea of communism as a massive grass roots reaction to the revolution’s social abuses. Firstly, the Industrial Revolution featured the construction of machines, systems and factories that allowed goods to be manufactured at a faster rate with a lower cost. The seed drill made it so there could be â€Å"a semi-automated, controlled dis tribution and plantation of wheat seed†(Jones 2013). SecondlyRead MoreIndustrial Revolution1160 Words   |  5 Pagesend of the 19th century, a significant change took place in the fundamental structure of the economy. That change was industrialization. During this time period, the United States of America changed from a large, agricultural country, to an urban industrial society. The process of industrialization began to take place in America, and eventually took over the economy during this period. Entrepreneurs and inventors put together various machines and businesses to help better the country function on aRead MoreThe Industrial Revolution Essay2099 Words   |  9 PagesThe Industrial Revolution was one of the largest social and cultural movements that changed the methods of manufacturing of metal and textiles, the transportation system, economic policies and social structure as well. Before the Industrial Revolution, people used to live by season due to agriculture. T hey thrived on whatever food was in season. Now, as a result of the Industrial Revolution, we live regimented and almost everything that is made, is mass produced. I will discuss three major topicsRead MoreThe Industrial Revolution2418 Words   |  10 PagesThe Industrial Revolution became a defining transitional period in United States history. The Industrial Revolution created opportunities for society through, employment, higher pay and allowed for the meeting of many cultures. As a result of high employment opportunities, people flocked to the North and populated areas of the nation creating urban cities. Urban cities of the nation have not changed much since the Industrial Revolution; people are still drawn to the urban culture because of the variety