Direct Seeding Literature Review Essay Example for Free

Direct Seeding Literature Review Essay Introduction: The world’s total forest area is just over 4 billion hectares, which corresponds to an average of 0.6 ha per capita (Figure 1). The five most forest-rich countries (the Russian Federation, Brazil, Canada, the United States of America and China) account for more than half of the total forest area. Deforestation – mainly the conversion of tropical forest to agricultural land – shows signs of decreasing in several countries. Around 13 million hectares of forest were converted to other uses or lost through natural causes each year in the last decade. At a regional level, South America suffered the largest net loss of forests between 2000 and 2010 – about 4.0 million hectares per year – followed by Africa, which lost3.4 million hectares annually (Figure 5). Oceania also reported a net loss of forest (about 700 000 ha per year over the period 2000–2010), mainly due to large losses of forests in Australia, where severe drought and forest fires have exacerbated the loss of forest since 2000. Asia, which had a net loss of forest of some 600 000 ha annually in the 1990s. Need of Forest Restoration: Within the last ten years, tropical rainforests have been destroyed at an annual rate of 0.8% of area (Whitemore, 1997). So this things brings to human being to think about the forest restoration. Forest restoration is defined as â€Å"actions to re-instate ecological processes, which accelerate recovery of forest structure, ecological functioning and biodiversity levels towards those typical of climax forest† Various forest restoration methods have been developed, for instance, the accelerated natural regeneration ( ANR) (Jansen and Pfeifer , 1989), The Framework Species method(Goosem Tucker, 1995) and The Maximum Species Diversity method. The ANR method is Effective where natural regeneration is already underway. Eliminates nursery and tree planting costs. Relatively cheap – Capitalizes on â€Å"free† ecological services US$ 1,400/ha. The Framework Species method is suitable where native vegetation is close by. Its only need a single planting and it is self sustaining. In the Maximum Species Diversity method a large percentage of species are from the mature phase and primary promoters are avoided. The major disadvantage of this method slower growth rate and post planting management is required. Now a days there is some evidence that , reforestation plays a key role in the long term of restoration of landscape functioning, as well as social and economic development. Reforestation can catalyses and induce succession of forest ecosystems using native species (Parrotta, 2000). Direct Seeding: An ancient method of establishing trees is by sowing seeds directly where the future trees are required. In many circumstances, this method is superior to the traditional method of planting nursery-raised plants. In several tropical countries, the demand for reforestation is often not met due to limited resources. Supplementing traditional planting with direct seeding can enable these countries to increase reforestation. Direct seeding is a regeneration method of sowing seeds directly where the future trees are required, whether it is for forest plantations, shelterbelts or in agroforestry. In this way the laborious task of raising nursery plants and transplanting them to the planting site is omitted. Direct seeding offers various interesting possibilities e.g. the ability to rapidly increase the area being forested or the ability to provide rural people with an inexpensive method to obtain benefits from trees. History of Direct Seeding: Direct seeding has over the last 50 years gained in importance, especially in North America and China where large areas have been direct seeded from helicopters or aero planes. Direct seeding from the air has been widely used in China where more than 15 million ha have been reforested between 1956 and 1985 (Xinhua Jingchun, 1988). In the developed countries more than 1⠁„2 million ha were reported to be direct seeded in 1974 or about 20 % of the area being planted (Appleroth, 1975). Direct seeding in the tropics is less reported compared with the subtropics (Australia and USA) or the temperate regions (USA, Canada and Scandinavia). Trials have been carried out and reported from various tropical countries for example Indonesia, Philippines, India, Central America, Northern Australia and the Sahel in Africa. Direct seeding in the tropics has been carried out many times without the results ever being published. In the dry tropics traditional forestry is limited and most trees are r aised in connection with agriculture. Here, direct seeding already plays an important role, this could increase in the future by being implemented in afforestation and in establishment of shelterbelts. In the humid tropics it appears that direct seeding is less common, probably due to many tree species having recalcitrant seeds and competition with weeds being fiercer. Nevertheless direct seeding has the ability to contribute significantly to tropical forestry in the future, probably not as the main regeneration method but as a method that under certain circumstances is superior to other methods. The following will describe various scenarios where direct seeding is employed in the tropics. Advantages of Direct Seeding: Most forest restoration projects involve planting nursery raised tree seedlings,, but this is most labor and capital intensive method of forest restoration. Seed collection, raising seedlings in a nursery, planting and maintaining planted saplings until they can establish and become independent all require substantial labor inputs (Hardwick et al., 2000). Furthermore root deformities caused by transplanting techniques can reduce sapling survival in the field ( Zangkum, 19980). The Potential advantages of direct seeding over other plantation establishment techniques include cost savings associated with nursery care and planting as well as the possibility that trees established by this means may develop more naturally or quickly, than would transplanted seedlings or cuttings( Engel Parrotta,2001). The Eden Project in Niger is recommending direct seeding as an appropriate method of establishing trees where water is scarce (Eden Foundation, 2000). It is claimed that nursery plant use precious irrigation water, whereas direct seeding carried out prior to or during the rainy season does not need irrigation. They further maintain that plantation established by direct seeding tend to produce extensive root system, whereas the above ground shoots grow more slowly. In contrast seedlings in nurseries tend to produce large shoots and have to be irrigated or they they will suffer high mortality, whereas plants that established through direct seeding are more likely to be able to reach moisture remaining in the soil after rainy season.(Oschner,2001). This was quantified by Samba (1992) who sowed the seeds of Faidherbia albida at the same time as planting as planting nursery raised plants. Four months after sowing direct seeded plants were about twice as tall and had a mean dry root mass 25 times higher than that of the nursery raised plants. The disadvantages of Direct Seeding: The significant disadvantages of direct seeding that can outweigh these advantages include low germination survival percentages, seedling mortality associated with weed competition and also poor weather condition (Evans, 1982). Steven stated that the results of direct seeding are affected by a number of factors including species, soil conditions, site preparation and techniques for seed germination. Garwood (1989) pointed out that seed destructed by animals also plays a key role in reducing seed germination. Direct Seeding in different purposes: Direct deeding can used for many purposes like for plantation, restoration, in mine spoils rehabilitation, in agro forestry. Negreros et al., 2003 worked in Mexico to restore the area by Mahogany seeds. Because this is very valuable for timber. He found that Burying Mahogany seeds were clearly better than sowing them on the soil surface and it yields double comapared to sowing method. For restoration purposes by direct seeding method, Tunjai and Elliott (2011) found that seed trait is very important to achieve the goal of forest restoration by this method. They said Large or intermediate sized seeds, Round or oval seeds, Medium or low moisture content seeds showed good establishment when they sowed in the field for forest restoration purposes. For mine site rehabilitation Parrotta and Knowles(2001) found that In term of species richness, densities and life span over 40 years Direct seeding got the most priority. They experimented with four forest restoration techniques and direct seeding showed the good result for rehabilitation mine site in Brazil. Factors effecting seed germination when applied by direct seeding: Seed germination is the activation of the metabolic machinery of the embryo, leading to the emergence of a new seedling ( Poulsen and Stubsgaard, 1995). Seeds of some species do not germinate due to hard seeed coats hindering intake of water ( Baskin Baskin, 1998). Seed treatments can be applied to break dormancy and improve the seed coat permeability. For germination to be initiated three conditions must be fulfilled: first seeds must be viable that the embryo must be alive and capable of germination. Second, the seed must be subjected to a proper environmental conditions, available water, proper temperatures, a supply of oxygen and sometimes light. Third dormancy must be overcome. ( Poulsen and Stubsgaard, 1995).However seed treatments can be applied to break dormancy and impro ve seed coat permeability such as scarification, soaking in water or boiling in hot water or hot sand.( Hardwick Elliott,1992). Problems with weeds: Studies conducted by Sun, Dickson and Bragg ( 1995) in Australia, found that the survival and early growth of Alphitonia petriei through direct seeding are largely affected by weed competition and site conditions. The death of germinated seedlings, a few weeks after germination in the plots where weeds remained undisturbed through out the experiment, was mot likely due to the effects of competition for light from the existing weeds. Results from both the glasshouse and field experiments also indicate that weed compition severely limited the early growth of Alphitonia. Frequent weeding is necessary during the early growth phase.(Engel Parrotta 2001). Problems with predation: Seed predation can be severe and looses up to 100% have been reported. (Crawley, 1992). Seed predation has identified as one of the biotic barriers to natural forest regeneration in the abandoned Amazon pasture derived from rainforest ( Nepstad et al., 1991). Garwood (1989) pointed out that seed destructed by animals also play vital roles in reducing seed germination. However Crouch And Radwan (1975) recommending seed coating and pelleting against seed predators. But little is known about this technique in tropical situation. The study of Woods and Elliott (2004) was designed based on the premise that scarifying seeds before sowing them in the fields cleared of weeds would shorten seed dormancy to decrease the time available for seed predation to occur and that burial conceals seeds from potential predator. They found that ants were the only predator observed. Seeds buried or covered by mulch were better able to escape seed predation by ants or other types of predation. Other problems: The results from Sun et al., 1995 showed that compacted and eroded soils are inhospitable to the establishment of A. petriei seedlings. So,at this point site preparation is necessary to overcome this problem. Points to achieve succession of using direct seeding: Sun et al.1995 conclude that weed control and maintenance of nutrient levels are essential for success. Engel and Parrotta (2001) suggested that what is required is a more systematic screening of potential species and their response to direct seeding under field conditions and evaluation of coast associated with plantation establishment and aftercare. Seed quality is also other concern, using fresh seeds collected from several parent trees growing on sites where soil and climatic conditions are similar to those being reforested and planting should be carried on high rainfall. Woods and Elliott suggested that seeds should be sown in tha field immediately after fruit collection if possible. In order to minimize seed storage, species selected for dirct seeding should fruit at the beginning of the rainy season when direct seeding is most likely to be successful. Areas where direct Seeding could get an importence: Many tropical species have recalcitrant seeds, e.g. most trees in the dipterocarp family. This means that the seeds deteriorate rapidly after collection and can only be stored for a short period. If transport and temporary storage can be reduced to a minimum by processing the seedlot at the collection site before direct seeding the seeds at the planned site, the whole operation may be done in fewer days compared to a solution with a central processing centre and a nursery. This solution should result in a seedlot with better germination and possibly a higher overall percentage of established plants. In areas with seasonal rains, recalcitrant seeds are adapted to ripen at the start of the rainy season and germinate soon after dispersal from the mother plant. Time for direct seeding will thus naturally be at the beginning of the wet season, just after collection of the seeds, where the rains will provide a good start for the seedlings. In contrast, nursery stock has to be planted out a year after seed collection at the onset of the next rainy season or alternatively at a time where drought can hinder the growth and survival of the seedlings. Many species will reach a fair size after a year in the nursery, resulting in more costly transport and planting of nursery stock compared to direct seeding. In Southeast Asia large areas of former rain forest lands have been turned into imperata (Imperata cylindrica) grassland, due to failure of reforestation. In Indonesia alone the latest estimate of Imperata grasslands is 8,6 million ha (Garrity et al. 1997). In these areas it is difficult for trees to establish naturally due to annual fires. Direct seeding in connection with constructing fire-belts could perhaps offer an alternative method to reforest these areas. In a trial in Jamaica a variety of trees was successfully established on grassland (Roshetko et al. 1991, 1991). It was concluded that trees can be established by direct seeding even with heavy grass competition, providing that monthly weeding is carried out until trees reach a competitive size. In a Nigerian trial Gliricidia sepium was both planted and direct seeded in Panicum maximum pastures after mechanical seedbed preparation (Cobbina 1994). Although planting showed better results, direct seeding could still offer a worthwhile alternative if expenses are taken into account. In order to compete with the imperata grass it would be sensible to start the reforestation with fast growing exotic tree species for example Acacia spp., Leucaena, Cajanus cajan or Sesbania spp. In order to obtain more valuable forest products planting or direct seeding of native primary forest species such as dipterocarps could be carried out at a later stage when the grasses have been outcompeted. Otsamo (2000) reported that native trees can be establish in the understorey of fast growing plantation species; he found 63 tree species in plantations on Borneo, which was established on former Imperata grasslands. Costs and benefits: Angel and Parrotta (2001) reported that the establishment and maintenance cost of direct seeding of five species in Brazil during the 2 years study period averaged 747-912 US $ per hectare. This cost compare favorably with those for plantation establishment and maintenance at this site using nursery grown seedlings of native tree species in other plantation treatments include in same project , which averaged1200- 1500 US $.(Unpublished data).Therefore direct seeding in this project can reduce about 63% compared with the plantation using nursery grown seedlings. References: Appelroth, S.E. (1975). Work study aspects of planting and direct seeding in forestry. In Symposium Stand Establishment; Proceedings, p. 202-269. Engel, V. L. and J. Parrotta, 2001. An evaluation of direct seeding for reforestation of degraded lands in central Sao Paulo state, Brazil. Forest Ecology an Management 152:169-181. Garwood, N.C.1989. Tropical soil seed banks. In: M.A. Leck, V.T. Parker and R.L. Simpson (Eds.). Ecology of soil seed banks. Academic press Newyork, 149-210. Goosem, S. and N.I.I. Tucker.1995. Repairing the rainforest. Theory and practice of rainforest re establishment. Wet tropics management authority. Cairns, Queensland, Australia.72 pp. Hardwick K (1999) Tree colonization of abandoned agricultural clearings in seasonal tropical montane forest in nothern Thailand. In, vol. Doctor of Philosophy. University of Wales, Bangor,p 168. Jansen, C.L. and S. Pfeifer.1989. Assisted natural regeneration: a new reforestation approach. USAID report prepared for the development of environment and natural resources. Government of the Philippines 22pp. Negreros CP, Hall RB (1996) First-year results of partial overstory removal and direct seeding of mahogany (Swietenia macrophylla) in Quintana Roo, Mexico. Journal of Sustainable Forestry 3:65-76 Negreros, C. P. and R. B. Hall, 1996. First-year results of partial overstory removal and direct seeding of mahogany (Swietenia macrophylla) in Quintana Roo, Mexico. Journal of Sustainable Forestry 3:65-76 Oschner, P. 2001. Direct seeding in the tropics. IUFRO Joint symposium on tree seed technology. Physiology and tropical Silviculture, College of forestry Natural Resources, University of the Philippines, Los banos. Parrotta JA, Knowles OH (2001) Restoring tropical forests on lands mined for bauxite: Examples from the Brazilian Amazon. Ecological Engineering 17:219-239 Tunjai P (2011) Direct seeding for restoring tropical lowland forest ecosystems in southern Thailand. In, vol. Doctor of Philosophy. Walailak University, Nakhon Si Thammarat, p 192 Woods K, Elliott S (2004) Direct seeding fo r forest restoration on abandoned agricultural land in northern Thailand. Whitmore, T. C. 1997. Tropical rainforest disturbance disapperance and species loss.In: W.F. Laurance And R.O. bierregaard Jr. (eds.0 . Tropical forest remmnants:Ecology management and Conservation of fragmant communities.(pp.3-12). Journal of Tropical Forest Science 16:248-259. Xinhua, C. and Z. Jingchun. 1988. Sowing from the air: China’s experience. Tigerpaper vol. XV: No. 1. FAO forest news. http://www.fao.org/docrep/013/i1757e/i1757e.pdf Zangkum, S. 1998. Growing tree seedlings to restore forests: effects of container type and media on seedling growth and morphology. MSc thesis, Chiang Mai Univerity, Chiang Mai.

Comparing Metaphors in Norman Macleans, A River Runs Through It and He

Comparing Metaphors in Norman Maclean's, A River Runs Through It and Henry David Thoreau's, Walden In Norman Maclean's A River Runs Through It, the author recounts the story of his early life growing up in Montana. The narrative revolves around his family and the art of fly fishing. Through the novel, Maclean begins to understand the wisdom of his father, the fierce independence and downfall of his brother, and the divinity and beauty of nature. A similar theme regarding divinity in nature is found in Henry David Thoreau's Walden. Building his own cabin and supplying his own food, Thoreau spends two years living alone beside Walden Pond. Thoreau recognizes nature as the "highest reality"(265) and the intrinsic work of "the Builder of the universe"(348). Thoreau also provides insights into human life and expresses these in indirect metaphors with his natural surroundings. The narratives differ most in their changes in mood and plot progression. In Walden, Thoreau displays a change from beginning to end, expressing pessimism and depression at first and then happiness and fulfillment in the end. A River Runs Through It is largely opposite of this change. Thus, both authors relate similar themes and experiences while significant differences exist in the mood and progression. One theme common to both narratives relates to how people are similar to bodies of water. Maclean illustrates this as he describes his brother Paul as being "tough"(8) and "very angry"(7) from his youth. Consequently, Paul's favorite river is the Big Blackfoot, which "is the most powerful and . . . runs straight and hard"(13). Maclean describes the river's "glacial origins"(14) and how it was formed overnight in "the biggest flood in the world"(14). Paul... ... glories in the beauty of nature and expressed how infinite man's possibilities are. In contrast, Maclean provides a valuable and realistic lesson, as his brother's premature death and his family's sorrow are the final details of his story. Despite, the depressing ending, Maclean expresses his belief in the permanence of one's legacy as he hears the words of his family echoed in the river. Thoreau states, "Yes, we have done great deeds, and song divine songs, which shall never die"(349). Thus, both works display compelling themes of nature and men's lives while differing substantially in their plot progression and mood. Works Cited Maclean, Norman. A River Runs Through It and Other Stories. Chicago: The U of Chicago P, 1976. Thoreau, Henry David. Walden. 1862. Walden and Other Writings by Henry David Thoreau. Ed. Joseph Wood Krutch. New York: Bantam, 2001. Comparing Metaphors in Norman Maclean's, A River Runs Through It and He Comparing Metaphors in Norman Maclean's, A River Runs Through It and Henry David Thoreau's, Walden In Norman Maclean's A River Runs Through It, the author recounts the story of his early life growing up in Montana. The narrative revolves around his family and the art of fly fishing. Through the novel, Maclean begins to understand the wisdom of his father, the fierce independence and downfall of his brother, and the divinity and beauty of nature. A similar theme regarding divinity in nature is found in Henry David Thoreau's Walden. Building his own cabin and supplying his own food, Thoreau spends two years living alone beside Walden Pond. Thoreau recognizes nature as the "highest reality"(265) and the intrinsic work of "the Builder of the universe"(348). Thoreau also provides insights into human life and expresses these in indirect metaphors with his natural surroundings. The narratives differ most in their changes in mood and plot progression. In Walden, Thoreau displays a change from beginning to end, expressing pessimism and depression at first and then happiness and fulfillment in the end. A River Runs Through It is largely opposite of this change. Thus, both authors relate similar themes and experiences while significant differences exist in the mood and progression. One theme common to both narratives relates to how people are similar to bodies of water. Maclean illustrates this as he describes his brother Paul as being "tough"(8) and "very angry"(7) from his youth. Consequently, Paul's favorite river is the Big Blackfoot, which "is the most powerful and . . . runs straight and hard"(13). Maclean describes the river's "glacial origins"(14) and how it was formed overnight in "the biggest flood in the world"(14). Paul... ... glories in the beauty of nature and expressed how infinite man's possibilities are. In contrast, Maclean provides a valuable and realistic lesson, as his brother's premature death and his family's sorrow are the final details of his story. Despite, the depressing ending, Maclean expresses his belief in the permanence of one's legacy as he hears the words of his family echoed in the river. Thoreau states, "Yes, we have done great deeds, and song divine songs, which shall never die"(349). Thus, both works display compelling themes of nature and men's lives while differing substantially in their plot progression and mood. Works Cited Maclean, Norman. A River Runs Through It and Other Stories. Chicago: The U of Chicago P, 1976. Thoreau, Henry David. Walden. 1862. Walden and Other Writings by Henry David Thoreau. Ed. Joseph Wood Krutch. New York: Bantam, 2001.

Importance of Attending All Your Classes

So have you ever asked yourself or wondered: What’s the importance of attending all your classes, and what’s the importance of actively participating in class discussions? Well you will soon find out that it is so very important that you do attend all your classes and that you are actively participating in class discussions. First let’s answer what’s the importance of attending all your classes? Well to start off with attending class helps you to learn in many different ways. Lectures help you out on reading assignments, class presentations show information differently than the text, discussion of topics provides current or new information, and hearing comments and questions of others may answer your own questions. Taking your classes seriously is the only way that you will ever do well in college. Going to class is a good thing because well you paid for it. Why throw your money away simply because you don't feel like going? Don't let your teacher get free money, and then give them an excuse to fail you. Why would you even sign up for college if you weren't going to go to class in the first place? There is no reason not to go to class if you are going to college. That is why you go to school, because you are taking classes to learn. It’s only beneficial to you! Moving on, what’s the importance of actively participating in class discussions? Well the most important reason is that the teacher will consider your participation as a positive sign you are listening, willing to cooperate and most importantly willing to learn. And it also means that you are alert and thinking about what's being taught. In addition you may have valuable opinions and ideas which your classmates or teacher may need or want to hear. If you don't speak up and share, how will they know? Also you learn more by challenging and discussing the idea or topic presented. And lastly some classes may give a participation credit. So the more you participate in class discussions the better participation grade you will receive and you’ll learn more that way too! So just go to class, and participate in class discussions. It can be annoying, but you will get more out of the class if you take if you actually go. Sure, class can be boring, and they can be really early or late sometimes, but it pays to go. You learn more, you get more information, it’s beneficial for you and you get the most for the money that you paid for school. It is a huge investment, and you should take it seriously.

The Issue Of Child Labor - 1196 Words

The issue of child labor has drawn significant attention since early 1990s as many labor union and special interest groups advocate banning import of goods produced by the child labor in developing countries and the international consensus in the form of Convention on the Right of the Child (CRC) which is widely ratified in 1989 by countries (Boyden, Ling and Myers, 1998). However, concern regarding child labor is not new and can be dated back to industrial revolution, especially late eighteenth and early nineteenth century, in England many parents were helpless but to send their children to work to cope the increasing poverty and inequality. (Horrell and Humphries, 1995; Edmonds, 2007). Nevertheless, before the industrial revolution and†¦show more content†¦There have been steady decline in the incidence of child s exposure to hazardous work and child labor on balance. However, the recent estimates of child labor are still astonishingly high and the trend predict even slowe r pace of decline in child labor. According to ILO report in 2012, for age group 5-17 years 16.7 percent (or 264,427 in absolute number) of children are in some form of employment, 10.6 percent (equivalently 167,956) is considered as child labor, and 5.4 percent (equivalently 85,344) is involved in hazardous work. Although these figures are lower than the corresponding figures in 2000, the absolute numbers of child labor are still very high (ILO 2013). Policy measures adopted to reduce child labor are derived from an increasing number of theoretical and empirical research on this issue specially since late 1990s. Theoretical studies use the household decision making model to explain the incidence of child labor and attempt to find the determinants of child labor. Initial models that attempt to explain the phenomenon of child labor assume an exploitative household where child is considered household s asset and parents are the sole decision maker who maximizes their welfare disregar ding the welfare of child. In these models parents are selfish and child labor is chosen if it maximizes household welfare which may disregardShow MoreRelatedThe Issue Of Child Labor Laws1461 Words   |  6 PagesThe United States of America has always been deeply ideologically split on the idea of child labor. On the one side, many people believe that children benefit from long hard hours at work because it prepares them for the real world unlike the ability of school. Along with the growth of the child, they also believe that it would create large economical growth throughout the nation. Among the many people that believe this are two of hour founding fathers, Benjamin Franklin and Abraham Lincoln. 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What can be done to resolve this global issue? Child labor is when companies use children to perform manufacturing duties— typically being paid in low wages. There are many different reasons and causes of child labor such as: poverty, globalization, and corruption. In some countries, however, child labor is considered a cultural norm. Although

Spanish Phrases Using Sangre

Blood has long been a symbol of life, so it shouldnt come as a surprise that the Spanish word for blood, sangre, makes itself into a wide variety of phrases, many of which have little to do with blood in a literal sense. One such phrase — sangre azul, meaning blue blood — has even made its way into English in the form of blue-blooded. As a term referring to someone from higher social levels, the Spanish phrase originally referred to the visible blood veins of people with fair complexion. The following are some of the most common sangre phrases along with an example each of their usage. Alguien in these phrases means someone, while algo means something. Spanish Phrases Referring To Blood chuparle a alguien la sangre (literally, to suck the blood out of someone): to bleed someone dry. El sector pà ºblico es el drà ¡cula que chupa la sangre de este paà ­s. The public sector is the Dracula that is bleeding this country dry.helar la sangre (literally, to freeze the blood): to scare stiff, to curdle the blood. No es una gran pelà ­cula pero tiene un montà ³n de sustos y uno en concreto me helà ³ la sangre. It isnt a great film, but it has a ton of frightening moments and one of them in particular scared me spitless.No llegà ³ la sangre al rà ­o (literally, the blood didnt arrive at the river): Things didnt get all that bad. Pero no llegà ³ la sangre al rà ­o y con el paso de los meses, Federico volvià ³ a casa. But it didnt turn out all that bad, and with the passage of the months, Federico returned home.llevar algo en la sangre (literally, to carry something in the blood): to have something in ones blood. Mi hijo lleva la mà ºsica en la sangre. My son has mus ic in his blood.quemar la sangre a alguien (literally, to scald someones blood): to make someones blood boil; to cause someone to be extremely angry. Me quemaba la sangre cuando salà ­ del cine. My blood was boiling when I left the movie theater. (The verb encender can be used instead of quemar.)de sangre caliente: warm-blooded. Con algunas excepciones, todos los mamà ­feros y aves son de sangre caliente. With some exceptions, all mammals and birds are warm-blooded.de sangre frà ­a: cold-blooded. No se sabe si los pterosaurios eran animales de sangre frà ­a. It is unknown whether pterosaurs were cold-blooded animals.de sangre ligera (literally, thin-blooded): having a likable personality. Aquà ­ descubrirà ¡ el espà ­ritu jovial de los habitantes, gente de sangre ligera que vive con una actitud positiva. Here you will discover the cheerful spirit of the inhabitants, a likable people who live with a positive attitude. (This term is used primarily in Central and South America. The opposite term is de sangre pesada.)sudar sangre: to sweat blood, to put forth an extraordinary effort. Te prometo que sudarà © sangre, si es necesario, para llevarte hacia mi lado. I promise you that I will sweat blood, if necessary, to bring you to my side.tener mala sangre (literally, to have bad blood): to have bad intentions, to be evil. Se necesita tener mala sangre para crear un virus destructivo. You have to be malicious to create a destructive virus.tener sangre de horchata (literally, to have the blood of horchata, a beverage often made from almonds, rice or tiger nuts): to be extremely calm, to have no feelings, to have the blood of a turnip. Normalmente en este tipo de situaciones tiene sangre de horchata. Normally under these circumstances hes very calm. (In some regions, the word atole, a corn-based drink, is used.)no tener sangre en las venas. (literally, to not have blood in the veins): for someone to not have any life (usually used figuratively in reference to e motions). El que pueda permanecer imperturbable y no baile con esta seleccià ³n es porque no tiene sangre en las venas. Anyone who can just stay still and not dance to this piece doesnt have any life in him.

Essay on John Steinbeck of Mice and Men Settings

John Steinbeck wrote ‘Of Mice and Men’ to show how hard life was for migrant ranch workers during the time of the Great Depression and how they were often exploited by their employers. In showing how George and Lennie’s dream of owning their own piece of land did not come true, Steinbeck explores a wider theme, criticising the idea of the American Dream. The American Dream tells people that there is ‘opportunity for each... regardless of the fortuitous circumstance of birth and position. Steinbeck criticises this as these ranch workers were given few opportunities. Settings play a very important part in the novel as they pinpoint clear times and places giving a sense of realism to the story, but they are also used to create atmosphere.†¦show more content†¦George and Lennie work on the land and their dream is to one day have some land of their own. When the Brush is revisited in section six, the quotation ‘a pleasant shade had fallen’, tells us that the atmosphere has changed. Also the animals tell us of a change as in section 6 the ‘beak lanced down and plucked it out by the head’ telling us of the water snakes death. This setting has altered than that of section one, where the animals were peaceful. ‘The rabbits sat as quietly as little grey, sculptured stones’ implies that they were minding their own business and safe as they were not scared of their surrounding until George and Lennie disturbed them. This is a large contrast between settings and tells us that in section 6, something must happen to explain the animals behaviour, implying a death. The Bunkhouse is another main setting in the novel and is important as it is where the readers are introduced to the rest of the characters. The bunkhouse is a functional building with not a lot of potential. This setting shows a sense of reality as it provides only the bare minimum to the ranch workers as if they do not deserve anything more. There are ‘eight bunks’ in the bunkhouse, with each one having ‘two shelves for personal belongings’, showing they don’t have enough money for a lot of things for themselves. Steinbeck is showing as if the ranch workers are not as good as the rest of the people.Show MoreRelated John Steinbeck Essay1174 Words   |  5 PagesJohn Steinbeck A novelist is someone who writes novels, or writes a fancy work of fiction which often has a complicated plot, many major and minor characters, a significant theme, and several varied settings. A novelist will use literary devices such as characterization, tone, symbolism, imagery, and figurative language. John Steinbeck, an American novelist, uses many literary devices such as metaphors, similes, imagery, and figurative language along with excellent descriptive words to developRead MoreAmerica Is Home To Many Great Writers Whom Come Different1709 Words   |  7 PagesAmerica is home to many great writers whom come different backgrounds. American authors like John Steinbeck who add biographical elements into their pieces of writing. John Steinbeck, one of the most honorable authors of time, is known for receiving Nobel Prize, California commonwealth club medal, Pulitzer Prize, and other great accomplishments towards publishing sixteen novels. Steinbeck’s realist style of w riting and life experiences impacting his life show the reader he’s been through a lot inRead More Comparing Of Mice and Men and John Steinbecks Life Essay849 Words   |  4 Pages   John Steinbecks agricultural upbringing in the California area vibrantly shines through in the settings and story lines of the majority of his works. Steinbecks novel, Of Mice and Men, takes place in the Salinas Valley of California. The drama is centered around two itinerant farm workers, George Milton and Lennie Small, with a dream of someday owning a place of their own. Lennie Small is a simple-minded, slow moving, shapeless hulk with pale eyes whose enormous physical strength often causesRead MoreJohn Steinbeck: An American Writer During the Great Depression1315 Words   |  6 Pagesand issues. They were motivated to arouse sympathy for the suffering of common people, especially those at the very bottom of the society. (Wang, 2012) John Steinbeck (1902-1968), born in Salinas, California, is one of the most significant and representative American writers in that era. He is the winner of the Noble Prize for Literature in 1962. John Steinbeck’s living experience in California had a great influence on his writing. He grew up in one of the richest agricultural place. Steinbeck’s lifelongRead More Truths Exposed in John Steinbecks Of Mice and Men Essay1045 Words   |  5 PagesTruths Exposed in Of Mice and Men  Ã‚        Ã‚   John Steinbecks timeless novel Of Mice and Men is a somewhat controversial story of the hardships of life. To illustrate these hardships, Steinbeck takes the reader back to an era of bankruptcies, migrant workers, and drifters. Today, this time, the 1930s, is branded the Great Depression. The quest of George and Lennie, two migrant workers, is an example of the dilemma of thousands of homeless and unemployed men in America during the Great DepressionRead MoreJohn Steinbeck s Of Mice And Men1319 Words   |  6 PagesBryann Cervantes AP English IV Mrs. Batey Of Mice and Men To most, John Steinbeck’s Of Mice and Men is a revered novel on racial segregation in the United States. This text has been remarkably controversial because of the way it deals with difficult issues regarding race and the American dream; however, despite its disputable history, it is an incredibly important book that is used to study many aspects of race relations in the United States in the early to mid twentieth century, more specificallyRead MoreOf Mice And Men By John Steinbeck Analysis1000 Words   |  4 Pagesâ€Å"Of Mice and Men† by John Steinbeck, portrayed the times of hardship and struggle in United States’ Great Depression. When two exorbitantly contrasting drifters, try to make enough money by working on ranches to achieve their variation of the American Dream. Steinbeck effectively got readers attention through each dramatic page and ended the novella with a drastic turn of events that will leave the readers in awe. Although many book conc erning the great depression may seem boring Steinbeck was successfulRead MoreOf Mice and Men by John Steinbeck973 Words   |  4 PagesIntroduction: I. Background A. John Steinbeck was born on February 27th, 1902 in Salinas, California. 1. Salinas River was one of the few centers for shipping, farming, and agriculture a. John Steinbeck worked as an employed laborer, digging canals and working beside men similar to characters in his novels. 2. In a discussion John Steinbeck said, I worked in the same country that the story is laid in. The characters are composites to a certain extent. Lennie was a real person. Hes in an insaneRead MoreAnalysis of Of Mice and Men by John Steinbeck1493 Words   |  6 PagesAnalysis of ‘Of Mice and Men by John Steinbeck ‘Of Mice And Men by John Steinbeck is a classic novel, tragedy, written in a social tone. The authorial attitude is idyllic, however, as the story develops it changes into skeptic. It is evident that Steinbeck knew the setting and places he is writing about. In my opinion Steinbeck drew the subject matter from his own experience of working on ranches, he was interested in special kinds of relationships among men working on ranches with him. ThereRead MoreEssay about Analysis of ‘Of Mice and Men by John Steinbeck 1488 Words   |  6 PagesAnalysis of ‘Of Mice and Men by John Steinbeck ‘Of Mice And Men by John Steinbeck is a classic novel, tragedy, written in a social tone. The authorial attitude is idyllic, however, as the story develops it changes into skeptic. It is evident that Steinbeck knew the setting and places he is writing about.

Epigenetic Determination (Influence) of Stress and Stress Related Dise

Question: Discuss about the Essay for Epigenetic Determination (Influence) of Stress and Stress Related Diseases. Answer: Introduction The ability of environmental factors, such as stress, to promote the epigenetic transgenerational inheritance of disease and phenotypic variation has now been established in a number of organisms ranging from plants to humans, with a variety of environmental exposures. One of the first studies found that environmental toxicants such as fungicides and pesticides promoted epigenetic transgenerational inheritance of reproductive disease. Subsequently a large number of different types of toxicants (plastics, hydrocarbons, dioxin, biocides, dichlorodiphenyltrichloroethane (DDT)) have been shown to promote the transgenerational inheritance of disease from obesity to cancer (Skinner, 2014). Other critical environmental factors found to promote transgenerational disease are nutritional abnormalities such as caloric restriction or high fat diets. Psychiatric disorders and in particular stress-related psychiatric disorders such as post-traumatic stress disorder (PTSD), major depressive disorder (MDD), and anxiety disorders are multifactorial diseases influenced by both genetic predisposition and environmental factors (Stankiewicz, Swiergiel Lisowski, 2013) Adverse life events, especially early in life, have consistently been shown to strongly increase the risk for mood and anxiety disorders in large epidemiological studies (Gudsnuk Champagne, 2012) Although severe forms of early adverse life events such as childhood abuse or neglect have been associated with the highest rates of increased risk (Covington et al., 2011) other forms of early adverse experiences, such as parental loss, bullying, or low socioeconomic status in childhood, were also shown to consistently increase risk for a number of psychiatric disorders . Finally, an increasing body of literature suggests that prenatal adversity, in the form of stress or mood and anxiety disorders of the mother, is also a risk factor for psychiatric disorders. A factor common to these early adversities is that they have all been associated with long-term changes in the regulation of the stress hormone system (Yamawaki et al., 2012), which may be causally related to the development of disease. In addition to the strong effects of the environment, there is a significant genetic contribution to the development of these disorders. However, strong main genetic effects have not been observed for stress-related psychiatric disorders to date, reflected by a lack of genome-wide significant associations in studies with sample sizes that have led to robust genetic association signals for schizophrenia and bipolar disorder (Covington et al., 2011). The genetics of stress-related disorders are therefore confronted with the so-called missing heritability that describes the lack of strong effects in the kind of gene-association studies found in twin and family studies. Th is is likely accounted for by weak phenotype definitions potentially leading to a dilution of genetic effects. Current diagnostic classification includes a number of pathophysiological subtypes under the broad definitions of anxiety and depressive disorders. In addition, genetic factors may have considerably smaller effect sizes compared to schizophrenia where they explained variance by polygenic factors has consistently increased with growing sample sizes (Yamawaki et al., 2012), In MDD, anxiety disorders, and PTSD, the reliable detection of such polygenic risk factors may need much larger samples. A deeper understanding of the pathomechanisms leading to stress-related psychiatric disorders is important for the development of more efficient preventive and therapeutic strategies. Epidemiological studies indicate a combined contribution of genetic and environmental factors in the risk for disease. The environment, particularly early life severe stress or trauma, can lead to lifelong molecular changes in the form of epigenetic modifications that can set the organism off on trajectories to health or disease (Bagot et al., 2014). Epigenetic modifications are capable of shaping and storing the molecular response of a cell to its environment as a function of genetic predisposition. This provides a potential mechanism for gene-environment interactions. Thus, in this study aims to explore the recent advances regarding the stress related influence on the epigenetics and the relation of stress with stress disorders. Background Animal and human studies have found correlations between poor care during infancy and epigenetic changes that correlate with long-term impairments that result from neglect. Studies in rats have shown correlations between maternal care in terms of the parental licking of offspring and epigenetic changes. A high level of licking results in a long-term reduction in stress response as measured behaviorally and biochemically in elements of the hypothalamic-pituitary-adrenal axis (HPA). Further, decreased DNA methylation of the glucocorticoid receptor gene was found in offspring that experienced a high level of licking; the glucorticoid receptor plays a key role in regulating the HPA. The opposite is found in offspring that experienced low levels of licking, and when pups are switched, the epigenetic changes are reversed (Bagot et al., 2014). This research provides evidence for an underlying epigenetic mechanism. Further support comes from experiments with the same setup, using drugs that can increase or decrease methylation. Finally, epigenetic variations in parental care can be passed down from one generation to the next, from mother to female offspring. Fe male offspring who received increased parental care (i.e., high licking) became mothers who engaged in high licking and offspring who received less licking became mothers who engaged in less licking. The experimental study of the effects of social interactions and stressful life events has relied primarily on laboratory rodent models (typically involving rats and mice), although some primate work is available to provide further support of the profound effects of early-life experiences (Bagot et al., 2014). The effects of prenatal stress, maternal deprivation and/or separation, variation in maternal care, juvenile social enrichment and/or isolation, and adult social stress have been explored in these models and suggest that the quality of social interactions or the experience of stress can induce neuroendocrine effects that influence social behavior, reproductive success, cognitive ability, and stress responses. Although it is clear that during prenatal and early postnatal development there is a period of enhanced sensitivity to these environmentally induced effects, there may also be plasticity beyond infancy that extends into adolescence and adulthood. An intriguing finding with in these studies is the long-term effects of early- and later-life experiences on region-specific gene expression in the brain. For example, exposure to stressors during fetal development or in early infancy is associated with an upregulation of genes involved in the hypothalamic-pituitary-adrenal (HPA) response to stress and a downregulation of genes that exert a dampening effect on these pathways (Bagot et al., 2014). These findings have led to further exploration of the molecular mechanisms involved in gene regulation that may mediate this lasting effect. Epigenetic mechanisms provide a dynamic strategy for changing the expression of genes and are increasingly the focus of studies examining the biological pathways through which early-life experiences exert long-term effects on gene expression (Pea et al., 2014). Across species, it is evident that epigenetic effects can be induced by a variety of experiences, including the quality of social interactions and exposure to stressors. Moreover, in some cases, these developmental effects can be transmitted across generations, leading to neurobiological and behavioral variation in offspring and grand-offspring (Pea et al., 2014). In this review, we highlight research indicating a link between social and stressful experiences occurring over the lifespan and epigenetic variation and the transgenerational implications of these effects. Although motivated by interest in determining contributions to the pathophysiology of human disease, this research is drawn primarily from studies in laboratory r odents and thus can also provide insights into the conditions of life that induce persistent biological changes in laboratory animals. We discuss the implications of findings from the now rapidly advancing study of behavioral epigenetics for laboratory animal treatment and housing conditions. Manipulating the quality of these conditions may have significant long-term consequences for animal welfare and, in particular, the stress physiology and reproductive success of laboratory animals. In humans, a small clinical research study showed the relationship between prenatal exposure to maternal mood and genetic expression resulting in increased reactivity to stress in offspring. Three groups of infants were examined: those born to mothers medicated for depression with serotonin reuptake inhibitors; those born to depressed mothers not being treated for depression; and those born to non-depressed mothers. Prenatal exposure to depressed/anxious mood was associated with increased DNA methylation at the glucocorticoid receptor gene and to increased HPA axis stress reactivity (Pea et al., 2014). The findings were independent of whether the mothers were being pharmaceutically treated for depression. Recent research has also shown the relationship of methylation of the maternal glucocorticoid receptor and maternal neural activity in response to mother-infant interactions on video. Longitudinal follow-up of those infants will be important to understand the impact of early care giving in this high-risk population on child epigenetic and behavior (Hunter, R., 2012). Environmental and epigenetic influences seem to work together to increase the risk of addiction. For example, environmental stress has been shown to increase the risk of substance abuse. In an attempt to cope with stress, alcohol and drugs can be used as an escape. Once substance abuse commences, however, epigenetic alterations may further exacerbate the biological and behavioral changes associated with addiction (Sun, Kennedy Nestler, 2013). Chapter 2: Methodology The systematic review methodology has been followed in this research. Systematic review can be classified as the secondary research method, as in this research, previous study findings is being analyzed and conclusion is being made based on these findings. The systematic review method is also dictated as the Meta analysis study. This research method has been selected as it helps to collect authentic secondary data related to the research topic and helps to analyze these data through the emergence of some relevant themes (Klengel Binder, 2015). This thematic analysis enhances the efficiency of study results. As, the topic Epigenetic influence of stress and stress related diseases has been researched well in previous studies, the Meta analysis or systematic review method for the secondary study was suitable. Literature search Relevant literatures have been searched from authenticated search engines including Pubmed, CDU library, Google scholar and Medline. In the process of literature search, initially, the topic has been put in the search area and the results were reviewed based on the abstracts. After going through the abstracts, the inclusion and exclusion criteria for this research study have been aligned with the studies. The studies, which were successfully aligned with the research exclusion and inclusion criteria, have been selected. For secondary data search, key words related to the topic have been used including, epigenetics, influence of stress, stress and stress related disease, epigenetic modification and epigenetic adaptation of brain. After getting the search results, these articles were analyzed by their titles initially. After excluding the non-suitable articles, the remaining articles were analyzed based on the abstracts and the appropriate ones were included. Then the final screening w as done according to the inclusion and exclusion criteria set for this study. According to that, the studies were selected and information reviewed. The studies were also checked for biasness and limitations. Finally 9 articles were selected for review. Inclusion or exclusion criteria Identify the report as a systematic review, meta-analysis, or both Not older than 10 years Includes a clear link between two variables of the study, stress and epigenetic influence Clearly understandable abstract with structured summary for the article including abstract, data source, findings and conclusion Qualitative research with or without thematic analysis Identify the report as a systematic review, meta-analysis, or both Describe method of data extraction from reports Discuss limitations at study and outcome level Search logistics In the following process the literature search has been done. Summary of selected journal articles Author Year Name of the article MichaelKSkinner 2014 Environmental stress and epigenetic transgenerational inheritance Adrian M. Stankiewicz, Artur H. Swiergiel, Pawel Lisowski 2013 Epigenetics of stress adaptations in the brain Kathryn Gudsnuk and Frances A. Champagne 2012 Epigenetic Influence of Stress and the Social Environment Rosemary C. Bagot, Benoit Labonte, Catherine J. Pea, Eric J. Nestler 2014 Epigenetic signaling in psychiatric disorders: stress and depression Richard G. Hunter 2012 Epigenetic effects of stress and corticosteroids in the brain Torsten Klengel, Elisabeth B. Binder 2015 Epigenetics of Stress-Related Psychiatric Disorders and Gene Environment Interactions Sun H1, Kennedy PJ, Nestler EJ. 2013 Epigenetics of the depressed brain: role of histone acetylation and methylation. Kathleen Saavedra , Ana Mara Molina-Mrquez , Nicols Saavedra , Toms Zambrano and Luis A. Salazar 2016 Epigenetic Modifications of Major Depressive Disorder Trump, S., Bieg, M., Gu, Z., Thrmann, L., Bauer, T., Bauer, M., ... Lawerenz, C 2016 Prenatal maternal stress and wheeze in children: novel insights into epigenetic regulation Chapter 3: Literature Review Overview of epigenetic regulatory mechanisms Epigenetic modes of gene regulation can be grouped into three general domains: (i) histone post-translational modifications (PTMs) and histone variant exchange; (ii) chromatin remodeling; and (iii) DNA methylation. While individually important, these mechanisms work together to orchestrate precise phenotypic outputs in mammalian cells. Also important for epigenetic control is the regulation of noncoding RNAs, which is not discussed here due to space limitations (Trump et al., 2016). Histone modifications The best-characterized mode of epigenetic regulation in brain is the post-translational, covalent modifications of histones.Histones are proteins that stably interact with DNA to form nucleosomes, which package DNA into chromatin.The nucleosome consists of DNA wrapped around an octamer of core histone proteins, two copies each of H3, H4, H2A, and H2B. For each of the core histones in mammals, with the exception of H4, variants exist that can exhibit significantly distinct structures, temporal regulation, and cell-type specificity from their canonical counterparts (Trump et al., 2016). Histone variants may also provide an alternative mechanism of encoding and transmitting epigenetic information. Figure: Chromatin structure and histone modifications at N-terminal histone tails. (A) The eukaryotic genome is organized by wrapping DNA around histone octamers to form the basic units of chromatin and nucleosomes, which are then further, organized and compacted into higher ordered structures. (B) The histone octamer consists of two copies each of H2A, H2B, H3, and H4. (Source: Sun, Kennedy Nestler, 2013) Interactions between DNA and core histone proteins can be altered by covalent modifications to histone N-terminal and C- terminal tails. Histone acetylation and phosphorylation decrease the affinity of histone octamers for DNA to loosen chromatin structure. This relaxed chromatin state, referred to as euchromatin, allows the transcriptional machinery, DNA binding proteins, and chromatin remodeling complexes access to genes and is often associated with active gene transcription. Methylation of lysine or arginine residues in histone tails is generally thought to be more stable than other histone PTMs, and plays roles in both transcriptional activation and repression depending on the residue being methylated (Sun, Kennedy Nestler, 2013). The enzymes that mediate histone modifications and their reversal can be understood as writers and erasers, respectively. For example, histone acetyltransferases (HATs) catalyze acetylation and histone deacetylases (HDACs) catalyze removal (deacetylation) of this mark. Similarly, histone methyltransferases (HMTs) catalyze methylation and histone demethylases (HDMs) catalyze removal of methylation marks. Proteins that bind to specific modified residues, termed readers, mediate the functional consequences of histone PTMs through effecting transcriptional change (Sun, Kennedy Nestler, 2013). Distinct roles for histone PTMs, along with their writers, readers, and erasers, led scientists to develop what is commonly referred to as the histone code hypothesis, which proposes that specific histone modifications work sequentially or in combination to form a code that can be read by other proteins to effect downstream changes in gene expression (Archer, 2015).While it is true that certain his tone PTMs is read in this way, it is becoming increasingly clear that a histone code per se does not work in isolation to direct the complex mechanisms of epigenetic regulation. Rather, this code cooperates with many other mechanisms, such as DNA methylation and chromatin remodeling, to produce a given phenotype. Chromatin remodeling With or without histone PTMs, nucleosomes themselves function as physical barriers to transcription.The precise positions of nucleosomes along DNA are controlled by chromatin remodeling complexes, which act to insert, slide, and eject histone octamers from the chromatin template. These multi-subunit complexes regulate the expression of many transcription factors. Chromatin remodelers also regulate alternative splicing, events that occur cotranscriptionally (Archer, 2015). It is likely that interactions between remodelers and associated transcription factors, other DNA binding proteins, histone PTMs, and DNA methylation, work together to direct remodeling activity in a manner that alters nucleosome positioning to affect gene transcription. DNA Methylation Historically, the most studied epigenetic modification is the direct methylation of DNA, involving the addition of a methyl group to cytosine (Branchi et al., 2011). DNA methylation is classically regarded as a highly stable epigenetic mark and can be maintained throughout the lifetime of an organism. DNA methyltransferase (DNMT) catalyzes DNA methylation and occurs most commonly at CpG dinucleotides (Curley et al., 2011). DNA methylation generally exerts a repressive effect on gene transcription, as exemplified by the X chromosome inactivation in females and genomic imprinting, where hypermethylation of one parental allele for a given gene results in monoallelic expression. methylated DNA is recognized by methyl-CpG-binding domain (MBD) proteins, such as MECP2 (protein-coding) and MBD1, whose binding can further recruit histone modifying enzymes and chromatin-remodeling complexes to compact nucleosomes and inhibit gene expression (Radtke et al., 2011). The process is also associated with splicing mechanism. Recently, additional DNA modifications have been discovered, including 5-hydroxymethylcytosine (5hmC), 5-formylcytosine, and 5-carboxylcytosine (Roth et al., 2011). These chemical modifications are thought to be derived from 5-methylcytosine through oxidation steps catalyzed by members of the ten-eleven translocation (TET) enzyme family, potentially representing a process of active DNA demethylation. DNA methylation in the brain may be more dynamic than in other tissues. Support for this idea comes from the discovery that: (i) the de novo DNA methyltransferase, DNMT3a, is the main DNMT expressed in neuron (Mahgoub Monteggia, 2013) (ii) the highest levels of oxidized forms of methylcytosine are found in the brain; and (iii) active DNA repair results in demethylated DNA in nondividing neurons (Hasan et al., 2013). There is also evidence that the primary effect of 5-hmC is to promote gene expression through mechanisms that remain poorly understood. Emerging themes from the literatures Epigenetic Impact of Prenatal Stress Chronic variable stress experienced by gestational females has been demonstrated to induce a long-term impact on HPA pathways, including altered gene expression within the hypothalamus. In mice, stress during the 1stweek of pregnancy has been found to induce significant impairments in male offspring (Skinner, 2014). Among male pups born to a stressed dam, CRF gene expression is increased and GR gene expression is decreased in adulthood. Analysis of DNA methylation within the promoter region of theCrfgene in hypothalamic tissue of stressed offspring versus control offspring indicates stress-induced reduction in DNA methylation. In contrast, within the promoter region of theNr3c1gene (encoding GR), prenatal stress is associated with increased DNA methylation. The direction of these epigenetic effects coincides well with the notion that increased DNA methylation leads to reduced gene expression. Although prenatal stress effects have been attributed to the direct exposure of the developing fetus to maternal glucocorticoids (Skinner, 2014). it is important to consider the placentathe interface between maternal and fetal physiological systemsas a mediating mechanism of prenatal effects. The expression of DNMTs in the placenta of prenatally stressed mice has been examined, and elevations in DNMT1 were observed (Skinner, 2014). Unlike the behavioral effects of this stress paradigm, stress-induced elevations in placental DNMT1 levels were observed in female offspring (with only a trend for an increase in males), which raises questions about the mechanisms of the sex specificity of prenatal stress. Prenatal stress exposure also has an impact on stress reactivity in adulthood. Chronic exposures produce exaggerated corticosterone responses to stress and a number of deficits in hippocampal structure and function. Variation in Early Postnatal Experiences: Effects on DNA Methylation and Histone Modifications Animal models of neglect, abuse, and variation in maternal care are increasingly incorporating analyses of epigenetic mechanisms to account for the persistent effects of these experiences. In mice, maternal separation (3 hours/day on postnatal days 110) has been found to increaseAvpgene expression in the PVN, and analysis of the promoter of this gene indicates decreased DNA methylation at several cytosine nucleotides within this region (Stankiewicz, Swiergiel Lisowski, 2013). These epigenetic effects are apparent at 6 weeks, 3 months, and 1 year after the experience of maternal separation. Hypomethylation of theAvpgene associated with maternal separation was also associated with reduced levels of binding of MeCP2 (a protein that binds to methylated DNA). Notably, MeCP2 is also associated with the primary pathology of Rett syndrome (Gudsnuk Champagne, 2012), and to play a role in the regulation of the expression of stress responsive genes such as BDNF. By means of a similar maternal separation paradigm, male offspring exposed to postnatal separation were found to have elevated levels of DNA methylation within theMecp2gene and decreased methylation within theCrfreceptor (Crfr2) gene (Gudsnuk Champagne, 2012). Abusive behavior toward pups has been found to induce significant changes in the epigenetic regulation of BDNF. Studies of Long-Evans rats indicate that daily exposure to 30 minutes of aggressive caregiving on postnatal days 1 through 7 is associated with increased DNA methylation of theBdnfpromoter at postnatal days 8, 30, and 90 (Gudsnuk Champagne, 2012). Although a limited range of targets has been explored, these initial studies suggest that epigenetic modifications, particularly DNA methylation, are associated with early-life manipulation of the quality and frequency of contact between dams and pups. Another early life stress model, using stressed and abusive dams, showed that the pups reared under these conditions showed reduced levels of BDNF expr ession in the prefrontal cortex, which correlated with DNA hypermethylation at the activity dependent exon IV promoter. The investigators were able to reverse this effect by infusing the DNA methylation inhibitor zebularine (Gudsnuk Champagne, 2012). Non-coding RNA and epigenetic effects of stress The effects of stress on non-coding RNA activity and the regulation of the stress axis by ncRNA in the brain, have received less attention than DNA methylation and histone modification, but the few studies thus far completed demonstrate that the epigenetic actions of RNA are also likely to be a significant part of the effects of stress upon the brain. The GR is the target of a number of miRNAs (Hunter, 2012). The effects of stress on non-coding RNA activity and the regulation of the stress axis by ncRNA in the brain, have received less attention than DNA methylation and histone modification, but the few studies thus far completed demonstrate that the epigenetic actions of RNA are also likely to be a significant part of the effects of stress upon the brain. The GR is the target of a number of miRNAs (Hunter, 2012). Activation of Transcription Factors that Lead to Local Changes in the Epigenetic Profile An additional molecular mechanism leading to long-term epigenetic changes in response to stress is the activation of specific transcription factors that in turn lead to local changes in epigenetic profiles. Early reports on the transcription factor Sp-1 showed that binding of Sp-1 leads to a local inhibition of de novo DNA methylation (Sun, Kennedy Nestler, 2013). Furthermore, glucocorticoid receptor (GR) activation can lead to a local demethylation of GR response elements (GREs) (Sun, Kennedy Nestler, 2013). The mechanism of GR-induced local demethylation has not been fully understood, but the DNA repair machinery was implicated in this process, allowing the replacement of methylated by unmethylated cytosines. This demethylation of GREs subsequently facilitates the transcriptional effects of the GR on the target gene (Sun, Kennedy Nestler, 2013). Another example is the activation of the Nuclear Factor 1 A-type (NF1A) transcription factor by maternal care in rodents. Weaver et al. showed that high levels of maternal care in early life are linked to serotonin signaling in the rat hippocampus with an increase in expression of the transcription factor nerve growth factorinduced protein A (NGFI-A). This is the transcription factor that binds to the I7 promoter of the rat GR gene, increasing its expression. Binding of NGFI-A leads to a decrease in methylation of the promoter with subsequent higher transcription factor binding and increased GR expression (Sun, Kennedy Nestler, 2013). Recently, collaborative effects of increased expression and GR promoter binding of the methyl-CpG-binding domain protein 2 (MBD2) and NGF1-A activation by maternal care have been implicated in this demethylation (Sun, Kennedy Nestler, 2013). From a Short-Term Stress-Induced Imbalance to Long-Lasting Dysregulation and Disease An altered mRNA transcription following exposure to environmental impact can be seen as a short-term compensatory reaction of the organism to maintain homeostasis and to overcome the environmental impact (Klengel Binder, 2015). These immediate responses at the transcriptional level do not inevitably lead to long-lasting epigenetic changes. The longterm epigenetic changes in response to a qualifying environmental stressor require a sequence of short-term immediate molecular responses leading to long-lasting epigenetic adjustments. An example for such concerted changes is the modification of the rodent arginine vasopressin (avp) promoter in response to maternal separation (Trump et al., 2016). Directly after a 10-day maternal separation period at postnatal day 10, the transcriptional activation of AVP is detectable with changes in phosphorylation of MeCP2 and protein occupancy but without changes in the DNA methylation. At this time point, the epigenetic memory has not been formed, an d it is an intriguing question to ask if an early intervention e.g., by compensatory high maternal care, could prevent the transition from short-term MeCP2 phosphorylation to DNA methylation changes (Trump et al., 2016). The long-lasting epigenetic changes are established in a subsequent step, engraving the short-term transcriptional change by creating a long-lasting epigenetic memory by a reduced DNA methylation at the avp enhancer site for MeCP2 in the paraventricular nucleus of the hypothalamus (PVN) of early-life-stress-exposed mice. These data suggest that the immediate response via phosphorylation of MeCP2 is subsequently replaced by DNA methylation changes that persist over time (Trump et al., 2016). This example highlights that an understanding of factors leading to long-lasting modifications might help in improving our abilities to prevent and treat stress-related disorders. Epigenetics and depression: development vulnerability It is well established that adults who experienced childhood stress or maltreatment are at a significantly greater lifetime risk for a range of mood or other disorders. It is well established that adults who experienced childhood stress or maltreatment are at a significantly greater lifetime risk for a range of mood or other disorders (Skinner, 2014). Histone modifications Very little is known about the prenatal effects of stress on histone modifications. Treatment with the nonspecific HDAC inhibitor valproic acid, which has many additional pharmacological actions, after prenatal stress was shown to ameliorate several behavioral measures (),although more work is needed to elucidate the mechanisms responsible for these effects. More is known concerning the consequences of postnatal adversity in the form of maternal separation. In stress-susceptible BALB/C mice, MS reduces levels ofHdac1, -3,-7,-8,and-10in the forebrain in adulthoods, and increases acetylation of histone H4 (Skinner, 2014).Adult male rats that underwent maternal separation had reduced levels ofHdac1mRNA,consistent with the elevated H3 and H4 acetylation levels reported in the HPC of juvenile mice after maternal separation (Yamawaki et al., 2012). Adolescent fluoxetine treatment potentiated effects of maternal separation, but coadministration of fluoxetine with an HDAC inhibitor ameliorat ed the effects of maternal separation (Covington et al., 2011).These findings suggest that adolescence may be a relevant period for pharmacological intervention and that it may be possible to erase at least some of the damaging epigenetic signature of early-life stress. Similarly, low maternal LG is associated with decreased HPC H3K9 acetylation at the glucocorticoid receptor(Gr)exon 17promoter.These modifications are associated with the expression of depressive-like symptoms, reduced gene expression, and changes in DNA methylation spanning large regions of the genome (Skinner, 2014).Treatment with the nonselective HDAC inhibitor trichostatin A, infused either intracerebroventricularly (ICV) or intra HPC, reversed both the molecular and behavioral effects of low maternal care. DNA methylation Under normal conditions, the developing fetus is largely protected from maternal glucocorticoids by the enzyme 11-hydroxysteroid dehydrogenase type 2 (11-HSD2), which converts active glucocorticoids to their inactive form. However, 10% to 20% of maternal Cortisol is estimated to pass through the placenta to the fetus (Covington et al., 2011). Evidence suggests that maternal stress during pregnancy induces a hypermethylation ofHsd11b2in the placenta and hypomethylation in the fetal hypothalamusthat may consequently interfere with11-HSD2enzymatic activity (Yamawaki et al., 2012)and induce heightened stress responses among offspring. Mice exposed to prenatal stress had elevated levels ofDnmt3aandDnmt1mRNA in the PFC and HPC at birth, changes that persisted at postnatal day 7, 14, and 60 (Skinner, 2014).Furthermore, prenatal stress increased binding of DNMTl and MECP2, along with increased 5-methylcytosine and 5-hydroxymethylcytosine, within theReelinandGad67promoters. Thus, existing evi dence points to a role of prenatal stress in altering adult vulnerability to depression, in part via changes in DNA methylation. These alterations occur in specific genes and in specific brain regions, highlighting the difficulty in using peripheral tissues to predict functionally relevant changes within the brain. Postnatal experience, particularly variations in the level and quality of maternal care, alters DNA methylation levels in genes thought to be critically involved in behavioral stress responses. For instance, the offspring of low-LG mothers, compared with those reared by high-LG mothers, exhibit robust DNA methylation changes that colocalized with chromatin modifications (Covington et al., 2011).This coincides with lower HPC expression of several variants ofGr,including the HPC specific variant 17 (Yamawaki et al., 2012).These alterations preferentially affect promoters, as evidenced in the cluster of protocadherin genes, and follow a nonrandom, discontinuous pattern across large genomic regions. Similar alterations have been reported in the HPC of suicide completers with a history of child abuse. Individuals with a history of abuse who committed suicide exhibit lower expression levels of the 1B, 1C, and 1Fvariants ofGrcompared with nonabused suicides and controls (Covington et al., 2 011).These changes coincide with altered DNA methylation within respective promoters that may interfere with transcription factor binding.Furthermore, similar alterations withinGrpositively correlate with different features of child abuse in individuals with major depressive disorders. Stress also alters epigenetic marks beyond the early neonatal period. Three weeks of adolescent isolation induced depressive-like behaviors accompanied by a sustained (12 weeks) hypermethylation of the tyrosine hydroxylase(Th)gene promoter in the VTA of aDisc1mutant mouse. Promoter hypermethylation was associated with bothDisc1mutations and adolescent isolation, and these effects were additive, although only in specific cell populations (Hollis et al., 2011). The impact of abuse becomes obvious when assessing the gene functions enriched with differential methylation: differential methylation in the abused suicide group is enriched in genes related to cellular plasticity, while learning and memory genes were particularly affected in suicide. This suggests that among depressed suicide completers, intense early-life adversity might induce distinct longlasting epigenetic alterations. Epigenetic Effects of Stress during Adulthood The hippocampus shows high expression levels for a large number of epigenetic enzymes, so it is unsurprising that both stress and memory formation have been shown to utilize epigenetic mechanisms at the level of the hippocampus. Fear conditioning is associated with a variety of short and long-term epigenetic changes. (Yamawaki et al., 2012) showed that fear conditioning causes increased expression of the DNA methyltransferases DNMT3A and DNMT3B and that the inhibition of these enzymes impaired the consolidation of fear memories (Hollis et al., 2011). Further, they found that fear conditioning altered DNA methylation on thereelinandPP1genes, both of which have an influence on memory in other models (Razzoli et al., 2011), as well as methylation of the BDNF gene (Hollis et al., 2011). PP1 is notable in that one of its activities seems to be removing phosphorylations from histone H3 at serine 10, and that this seems to be the basis for its role in long-term memory (Hollis et al., 2011). A subsequent study established that HDAC2 was the major neuronal class I HDAC and the HDAC responsible for modulating memory and synaptic plasticity, via a surprisingly select number of genes, including glutamate receptor subunits and BDNF. These findings provide the outlines of a complex set of interactions between memory, stress, or fear, a number of different epigenetic actors and long-term plasticity of the brain and behavior. With regard to explicit examinations of the effects of stress upon epigenetic modifications in the brain one of the earliest findings found that forced swim stress produced a significant increase in phospho-acetylation of Histone H3, at serine 10 and lysine 14 (H3S10p-K14ac) respectively, in the dentate gyrus of the hippocampal formation (Hollis et al., 2011). This combination of histone marks is associated with a transcriptionally active chromatin state. His initial finding established that a similar induction was produced by novelty stress and the phenomenon wasN-Methyl-D-aspartate (NMDA) receptor dependent and associated with c-Fos induction in the same cells, which showed the H3S10p-K14ac signal. Voluntary exercise, which is typically protective against the negative sequelae of stress, actually increases the levels of H3S10p-K14ac after both novelty and swim stress, suggesting that this may be part of an adaptive stress response rather than a pathological one. Social defeat stress, which represents one of the stronger models of human depression in terms of ethological and face validity (Razzoli et al., 2011), has a clear epigenetic component. Razzoli et al., ( 2011) found that chronic social defeat profoundly increased the levels of the repressive histone mark H3 lysine 27 dimethyl at promoter regions of the BDNF gene, while treatment with antidepressants produced and increase in activating marks such as histone H3 acetylation and histone H3 lysine four dimethylation (Tsankova et al., 2004, 2006). Subsequent studies found associations between chronic cocaine and social stress and HDAC5 (Renthal et al., 2007), as well as an antidepressant effect of HDAC2 in the social defeat model. In the study of Razzoli et al., (2011), it has been shown that Psychological stress during pregnancy increases the risk of childhood wheeze and asthma. Since epigenetic alterations have emerged as a link between perturbations in the prenatal environment and an increased disease risk we used whole genome bisulfite sequencing (WGBS) to analyze changes in DNA methylation in mothers and their children related to prenatal psychosocial stress and assessed its role in the development of wheeze in the child. The authors evaluated genomic regions altered in their methylation level due to maternal stress based of WGBS data of 10 mother-child-pairs. These data were complemented by longitudinal targeted methylation and transcriptional analyses in children from our prospective mother-child cohort LINA for whom maternal stress and wheezing information was available (n=443). High maternal stress was associated with an increased risk for persistent wheezing in the child until the age of 5. Both moth ers and children showed genome-wide alterations in DNA-methylation specifically in enhancer elements. Deregulated neuroendocrine and neurotransmitter receptor interactions were observed in stressed mothers and their children. In children but not in mothers, calcium- and Wnt-signaling required for lung maturation in the prenatal period were epigenetically deregulated and could be linked with wheezing later in childrens life. Chapter 4: Findings The study aimed to review the recent advances in the field of epigenetics and its relation with stress and stress related diseases. Here, the study revealed similar findings from the articles selected for reviewing. All the studies showed relationship of the epigenetic modification with environmental stressors. Studies found the role of non-coding RNAs and histone proteins based on the epigenetic signaling and it has been found that stress and depressive signs can stimulate the histone and DNA methylation or acetylation. Hollis et al., (2011) found that the gene transcription modification in prenatal stage can have significant effect in adulthood. One study showed the role of corticosteroid signaling in epigenetic modifications. On the other hand, 7 articles discussed about the role of histone modification as the significant effect of stress events. Several themes emerged from the previous studies, which have been reviewed further. The effect of pre and perinatal stress on epigenetic modificantions has also been evaluated (Chen, Ernst Turecki, 2011). 3 studies showed the effect of exposure to Prenatal Stress and its implications for brain development and behavior in animal model. One study findings included therapeutic implications of epigenetic modifications inhibitors can successfully combat with stress related symptoms. Chapter 5: Discussion and Conclusion These studies suggest that the experience of stress, whether during early-life or adulthood, has profound, genome-wide epigenetic consequences in the brain and peripheral tissues. Modifications of DNA methylation signatures in different regions of the brain are a plausible mechanism to explain how stress can induce enduring behavioral alterations. Peripheral tissues may provide biomarkers of stress exposure and vulnerability, although this remains to be determined. Skinner (2014) found that a sleep deprivation stress caused significant changes in the expression of 10 miRNAs in the mouse brain, as seven of these did not change in adrenalectomized mice, it is probable they are regulated by corticosteroids (Gudsnuk and Champagne, 2012). While the relations of whole classes of ncRNA's to stress and the stress axis remain to be explored, it can be said that ncRNA has a clear relation to the epigenetic tuning of the stress response and will likely provide a novel avenue to understanding stress and its associated pathologies. Given that, the prenatal period is susceptible to external stimuli that can shape the epigenetic landscape and thereby determine disease susceptibility later in life. Gudsnuk and Champagne (2012) found that both mothers and children experienced genome-wide perturbations in DNA-methylation affecting genomic regulatory elements in particular enhancer elements. Although this preferential deregulation in DNA methylation has already been described in disease states especially in cancer, the results show that also changes in the prenatal environment can lead to perturbed enhancer methylation already at a time at which no disease phenotype has yet developed. Epigenetic perturbations in DNA methylation by stress are not random but rather preferentially occur in enhancer elements regulating more than one gene in the genome, which might contribute to the broad ramifications for childrens health attributed to maternal prenatal stress. Stressful life events have been widely related to changes in the cortisol mediated stress response. DNA methylation of NR3C1 (glucocorticoid receptor) as the key mediator of this response has been associated with different types of stressful life events. The study showed that the epigenetic modifications of Wnt-signaling affected the alveolar differentiation and alters the lung development (Gudsnuk and Champagne, 2012). Alterations in epigenetics mechanism, such as DNA methylation, histone modification and microRNA expression could favor MDD advance in response to stressful experiences and environmental factors. The animal models in this review demonstrated that long-term epigenetic impact of agonistic social experiences, whereas communal care and juvenile social enrichment improved the benefits of social contact. As is the case for maternal behavior, modulation of the impact of social experiences will likely depend on contextual factors, particularly factors that increase or decrease HPA responses. Thus, housing conditions within the laboratory and manipulations of those conditions during experimental protocols may induce molecular changes followed by a long-term impact on social and anxiety-like behaviors. Studies presented in this review showed that stress-induced epigenetic changes can be reversed in adulthood using agents such as HDAC inhibitors or methyl group donors (Bagot et al., 2014). Functional effects of such treatment have been confirmed in studies on rodents and epigenetic drugs are already being developed (Hunter, 2012). Additionally, at least some of the epigenetic mechanisms active during stress are shared between rodents and humans, providing rationales for translatory potential. For example, perinatal epigenetic programming of GR expression seems to follow this logic, as the same changes were found in hippocampi of both postnatally stressed adult mice and human suicidal victims with history of child abuse (Gudsnuk Champagne, 2012). Unfortunately, potential unspecific and undesirable effects of such systemic treatment seem troubling. Only through more comprehensive research of epigenetic mechanism we may be able to develop safe and effective epigenetic-based therapies. The study of Klengel and Binder (2015) supports a role of ancestral stress in the epigenetic transgenerational inheritance of disease. Although direct stress exposure of adults can influence pathologies in the individual and offspring, the multigenerational versus transgenerational inheritance characteristics of the pathology need to be considered. A direct exposure generally affects somatic tissues that will be critical for the individuals disease, but a transgenerational effect requires a transmission of epigenetic information by the germline. Often, as shown in the current study (Sun, Kennedy Nestler, 2013), the transgenerational disease and pathology is distinct and/or has greater frequency than the direct exposure pathology In conclusion, it can be said that the complex epigenetic regulatory orchestra is just beginning to be understood. The role of many of its components such as non-coding RNA, 5hmC, histone variants and the editing of nucleic acids is still largely unknown. Without recognition of the impact of temporal dynamics, cellular diversity and systemic approach, both intra- and inter-cellular or structural, the final picture of the pathway from experience to changes in gene expression and behavior may continue to be vague and elusive. The study findings has been explored the research aim and established the influence of stress and stress related diseases on epigenetic changes. A variety of environmental factors promote the epigenetic transgenerational inheritance of disease. The observation that environmental stress can also promote transgenerational pathologies suggests ancestral stress conditions may be a significant factor in our own disease and what we pass down to our grandchildren. Several studies have considered the multigenerational impacts of stress on future generations, including World War 2 holocaust survivors offspring and traumatic stress generational effects in several African countries. The concept that ancestral stress, particularly during gestation, may influence disease etiology for generations to come is an important aspect to consider in regards to our environment and society. . Several studies now support the role of environmental stress in promoting the epigenetic transgenerational inheritance of disease. Observations suggest ancestral environmental stress may be a component of disease etiology in the current population. This is a no vel concept that will need to be seriously considered in future health management and therapy. Reference List Archer, T. (2015). Physical exercise as an epigenetic factor determining behavioral outcomes.Clinical and Experimental Psychology,2015. Bagot, R. C., Labont, B., Pea, C. J., Nestler, E. J. (2014). Epigenetic signaling in psychiatric disorders: stress and depression.Dialogues Clin Neurosci,16(3), 281-295. Branchi, I., Karpova, N. N., DAndrea, I., Castrn, E., Alleva, E. (2011). 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