Cell Adhesion Molecules in Olfactory Connection Formation

Cell Adhesion Molecules in Olfactory Connection Formation This dissertation study investigated expression, function and the regulatory mechanism of cell adhesion molecules in the formation of olfactory connections. Identification and characterization of a novel protocadherin, Pcdh20, provided additional evidence that multiple cell adhesion molecules are involved in the development of the olfactory system. In combination with several established studies by Sakano and Yoshihara’s group, my study further supports the neural identity model and provides a regulatory mechanism involving MeCP2 in the establishment and maintenance of this combinatory cell adhesion molecule expression in the olfactory sensory neurons. OR identity in correlation with cell adhesion molecule expression Though many cell adhesion molecule expression patterns were described, few of them were correlated with specific ORs. On the other side of the coin, it is also unknown whether a specific OR is correlated with a specific set of cell adhesion molecules throughout development. In adult mice, Pcdh20 expression is in a subpopulation of OSNs and their axons terminate in a small number of discrete Pcdh20-positive glomeruli in the OB. Interestingly, the distribution and numbers of Pcdh20-positive glomeruli are markedly different across gender. More Pcdh20-positive glomeruli with a wider distribution pattern are observed in the male OB, whereas fewer glomeruli with more restricted clustering of Pcdh20-positive glomeruli are found in female OB. The sexually dimorphic expression of Pcdh20 suggests that there may be different ORs associated with Pcdh20 in different sexes. 103 If Pcdh20 expression is correlated with specific OR expression, identification of Pcdh20 associated ORs could reveal possible sex-specific OR expression and aid in further investigation of OR-specific ligand function. In previous studies, cDNA libraries from a single OSN were obtained. OR expression in a single OSN can be identified by PCR using degenerate primers (Dulac and Axel, 1995). In collaboration with Dr. T. Cutforth from Stanford University, I have initiated this study by isolating single OSNs by dissociation of OE and attempting to identify Pcdh20 expressing cells by PCR. Several attempts were made to confirm OR expression using degenerate primers designed by L. Buck (Buck and Axel, 1989). Though I will not be able to complete this study during my dissertation research, identification of Pcdh20 associated ORs will provide important insight into not only OR and CAM association but also understanding of differential OR gene expression in different sexes and whether or not the main OB is related to pheromone recognition. Neuronal activity and regulation of cell adhesion molecule expression Neuronal activity results in long term changes in neurons by regulating gene expression. OSNs constantly respond to external stimuli throughout the life of the animal. Using genetic models and surgical manipulations, it is shown that blocking odorant evoked activity alters the expression of selected cell adhesion molecules. Even though regulation of cell adhesion molecule expression is important for the formation of olfactory axonal converge into glomeruli, the regulatory mechanism of gene expression is undetermined. I reported here that olfactory axon convergence is disrupted in MeCP2 null mice. Furthermore, I also obtained evidence that MeCP2 directly regulated Kirrel 2/3 expression. In MeCP2 KO mice, significant increases in Kirrel2/3 gene transcripts were observed in OE, suggesting that MeCP2 is a transcription suppressor for Kirrel 2/3 gene expression. In addition, my data provide evidence that MeCP2 function is regulated by neuronal activity. With the presence of odorant evoked 104 activity, MeCP2 is phosphorylated at Serine80 and also possesses enhanced binding affinity to promoters of Kirrel2 and Kirrel3 genes. Though MeCP2 increased its binding to promoters of both Kirrel2 and Kirrel3, transcript level changes are markedly different between Kirrel2 and Kirrel3 under odorant stimulation. Other transcription factors were shown to be regulated by neuronal activity. It is likely that both Kirrel2 and Kirrel3 are regulated under multiple neural activity dependent transcription factors. We propose a model in which a balanced transcriptional regulation from both repressors (like MeCP2) and enhancers (like CREB, MEF) determines the expression levels of Kirrel2 and Kirrel3. When both repressor and enhancer are under neural activity regulation, how the balance tilts will determine whether Kirrel2/3 expression will be up- or down-regulated in OSNs. In this study, the olfactory system serves as an excellent model system to study gene regulation of MeCP2 by neuronal activity at physiological levels. Previously, the mechanism of MeCP2 on gene expression regulation by neuronal activity was only studied in vitro. The brain is composed of heterogeneous cells and their neuronal circuits are extremely complex. In contrast, the OE is composed of a single type of neuron. This property provides an opportunity to study neuronal subtype specific MeCP2 function. In addition, the olfactory system provides an excellent system to study the effect of neuronal activity due to it accessibility. Odorant stimulation can be given to the OSNs in the nasal cavity to allow investigation of gene regulation under physiological level of stimulation. To further investigate the model we proposed, it is important to elucidate the full spectrum of MeCP2 target gene regulation. Future study should be done to screen MeCP2 target binding through ChIP-Chip analysi s. MeCP2 binding sequence will provide information in the target genes they regulate in the OSNs. To further provide or block odorant evoked activity, changes in MeCP2 binding will allow us to identify target genes that are activity dependent. Furthermore, identification of odorant evoked activity dependent transcription enhancers in OSNs will allow further  validation of the regulatory model we proposed here. Understanding neural activity dependent MeCP2 function is critical in elucidating the mechanisms of Rett Syndrome. Though rapid progress has been made in the identification of MeCP2 targeting genes, we still do not understand how changes in gene expression result in neuronal structural and functional changes. Rett Syndrome is exacerbated during the early postnatal period. Neural activity plays a critical role in this process. Understanding the relationship between physiological levels of neuronal activity and MeCP2 regulation is the obvious next challenge. The olfactory system provides an excellent model for the easy manipulation of activity stimulation and examination of subtle axonal targeting defects. This study established that cell adhesion molecules are regulated by MeCP2 in an activity dependent manner. Further genomic analysis will provide a comprehensive understanding of MeCP2 regulation of gene expression and could help in the development of treatment strategies for Rett Sy ndrome.

Les Miserables :: essays research papers

Les Miserables, by Victor Hugo, starts out with Valjean saying how he is 19 years old and a thief. The novel goes through his whole life. It explains the many conflicts he faces. But mainly it shows how he tries to escape his past during the French Revolution. Valjean was not a very wealthy man. He stole a piece of bread because he was hungry. He got tried and committed as if he had done a major crime and served 5 years in prison. He ended up doing 19 years of hard labor because he had tried to escape and failed. After he got out he had no where to go. A forgiving bishop decided to take him in. He feeds him and gives him clothes and shelter. Even after all that the bishop has done for him, Valjean steals silverware from the bishop. Once the bishop found out it was him who had stole it, the bishop tells the police that he gave it to Valjean, so Valjean could get off. After this Valjean decides to shape himself up. He sold the silver and moved to a town up north. He gets a job and he tries to start a life. Not only did he change his name, but he becomes a changed person as well. He eventually becomes mayor of this town. However, his past comes to haunt him. A police officer, which goes by the name of Javert, followed him to this town. Javert accuses another man of being the thief, so Valjean, being a changed man, turns himself in to save an innocent man. Eventually, Valjean escapes. When he is out he meets this woman Fantine, who is a prostitute. She is very sick and Valjean helps nurse her. On her deathbed, Fantine asks Valjean to take care of her daughter who is now owned by a money hungry family. Valjean agrees and buys her daughter, Cosette, from this family. He then takes her and all of the money he has left and flees to Paris. The novel then moves to 9 years later. This is during the French Revolution. Cosette is now a young adult. She meets a student revolutionary named Marius. Javert, the police officer, is trailing Marius. That brings Javert back on the trail of Valjean. Once again, he can not escape his past. Cosette and Marius fall in love and plan to wed. Les Miserables :: essays research papers Les Miserables, by Victor Hugo, starts out with Valjean saying how he is 19 years old and a thief. The novel goes through his whole life. It explains the many conflicts he faces. But mainly it shows how he tries to escape his past during the French Revolution. Valjean was not a very wealthy man. He stole a piece of bread because he was hungry. He got tried and committed as if he had done a major crime and served 5 years in prison. He ended up doing 19 years of hard labor because he had tried to escape and failed. After he got out he had no where to go. A forgiving bishop decided to take him in. He feeds him and gives him clothes and shelter. Even after all that the bishop has done for him, Valjean steals silverware from the bishop. Once the bishop found out it was him who had stole it, the bishop tells the police that he gave it to Valjean, so Valjean could get off. After this Valjean decides to shape himself up. He sold the silver and moved to a town up north. He gets a job and he tries to start a life. Not only did he change his name, but he becomes a changed person as well. He eventually becomes mayor of this town. However, his past comes to haunt him. A police officer, which goes by the name of Javert, followed him to this town. Javert accuses another man of being the thief, so Valjean, being a changed man, turns himself in to save an innocent man. Eventually, Valjean escapes. When he is out he meets this woman Fantine, who is a prostitute. She is very sick and Valjean helps nurse her. On her deathbed, Fantine asks Valjean to take care of her daughter who is now owned by a money hungry family. Valjean agrees and buys her daughter, Cosette, from this family. He then takes her and all of the money he has left and flees to Paris. The novel then moves to 9 years later. This is during the French Revolution. Cosette is now a young adult. She meets a student revolutionary named Marius. Javert, the police officer, is trailing Marius. That brings Javert back on the trail of Valjean. Once again, he can not escape his past. Cosette and Marius fall in love and plan to wed.

I got a D for this TOK Essay Essay

4. The traditional TOK diagram indicates four ways of knowing. Propose the inclusion of a fifth way of knowing selected from intuition, memory or imagination, and explore the knowledge issues it may raise in two areas of knowledge. Word count: 1207 Memory is a tool people use to process things they come to learn about the world. In psychology memory is described by the term cognitive processes which include perception, thinking, problem solving, memory, language and attention. Cognition is ones mental perception of the world like images, words and concepts. Memory is not an exact copy of experiences but an outline. What people actually remember and what they have been told by someone else, is mixed so the thing people remember and thinks is the truth is a lie. This is called false memory and the brain would make an illusion or use imagination to twist the truth around. In this connection where people can manipulate memory questions may arise about the trustworthiness in a witness testimony. Also when people can manipulate memory how reliable is memory as a way of knowing. If a person witnessed a robbery and testified to the police about what they saw, you would not believe that a person would lie but if the policeman were to ask the wrong question people would subconsciously lie about what they saw. For example if a police man could ask, what colour shirt was he wearing? The witness would thing about the colour of the shirt but if instead he asked, what colour shirt was he wearing? Green? Blue? The witness might mention one of those colours the police man mentioned. So the witness could accidently give a false testimony because the policeman’s question was not neutral hence, the witness got false memory. This would be a connection to history as a area of knowing, history books consist of memories written down. Some history books are of primary memory, written by people who have experienced a historical aspect and secondary memory, written by people who have been told by another person who had experienced a historical aspect. Since memory is not always remembered correct history books can be wrong. Memory is one of the most important ways by which our histories animate our current actions and experiences. Memory seems to be a source of knowledge. We remember experiences and events which are not happening now, so memory differs from perception. We remember events which really happened, so memory is unlike pure imagination. Yet, in practice, there can be close interactions between remembering, perceiving, and imagining. Another area of knowing were memory is used is the arts. Actors, musicians and dancers use memory to remember words, notes and choreography. How they do this is by using motion, a required motion on stage, so the moves help the brain to recall stored information. Communication, reading lines out laud, even in early stages and try to visualise an audience you have to communicate to. Internalization, make the lines personal, to become the character, dancer or musician. In the way of knowing memory plays a big role in inductive reasoning and you could ask, to what extent is reason based on previous memory experience? We jump to conclusions in inductive reasoning as the results of our memory since memory is the key to remember past events, for example a person has only seen a red rose all his life so therefore all roses must be red but that is not true because there are many different coloured roses and this is called the problem of induction. If something has happen often in the past, there is a good chance it will do so again. The conclusions are drawn from limited evidence because we have no choice but to do so, most of the times this seems reasonable but sometimes not, we need to consider if the evidence supports a conclusion and when it doesn’t. Also in deductive reasoning we use memory to make generalisations and to draw similarities between issues, objects and thought. In deductive reasoning we would use memory to know what is required of valid and a true argument. In language also a way of knowing, memory is used to remember and understand the †codes† ,â€Å"symbols† and sounds in order to learn and communicate the language that is being taught. If we weren’t able to remember the†codes†, â€Å"symbols† and sounds when learning a language, languages would be meaningless. Because all we would just have been taught would be forgotten right away. Sense perception, a way of knowing, can only be used if we can remember what we see, hear, feel, smell and taste. Without memory we wouldn’t be able to recall these senses and perceive them. The other way around sense perception is a big trigger of memory, if for example the smell of a horse triggers my memory to think of my childhood because I grew up on a farm with horses so I would connect those things together, the smell of horses = my childhood. The same if a heard a specific song in an important moment of my life then when I heard that song later on in life I would think of that moment. Big event makes people remember too for example 9/11, people can remember what they were doing and where they were at the moment they were told or saw it on the news. Emotion is one of the ways of knowing which most people would argue could do without memory since it acts on impulse. However emotions are based on past experiences like affection and hatred towards somebody due to past events. In the dictionary emotion is described as particular type of mental state similar to memory. People remember differently and they need to know what type of learner they are. Some people are visual learners and others are audio learners. Visual learners need to see things to understand them for example in chemistry a visual learner needs to see the atom to understand what it is. An audio learner would need to hear the things they need to learn out laud and would not be able to understand it if the person had to read things to learn. If we know which type of learner we are we can better learn and learn faster. Memory is an important skill to have because without it we would not be able to exist. We would not be able to remember what we like, were we live, who to trust or what is right and wrong. Memory is the essential thing that the ways of knowing are build and based. It links all the ways of knowing together because all the ways of knowing needs memory to work precisely. Memory would not necessarily be a fifth way of knowing since there are many  flaw to memory, but I think that it connects the ways of knowing and it is an important skill to have so we can learn and use the accepted ways of knowing. Memory could be the overall term of ways of knowing and the four ways of knowing could be under the memory category. Bibliography Books Crane, John and Hannibal, Jette, Psychology course companion, Oxford university press, 2009 Alchin, Nicholas, Hodder Murray, 2003 Internet pages http://plato.stanford.edu/entries/memory/ http://theater.about.com/od/careersintheater/a/actors-memory.htm http://www.ibsurvival.com/topic/13374-memory/ http://pottsiex5.wordpress.com/2012/02/22/tok-reflection-memory/

Description of what you have experienced as a major joy or a series of smaller related joys.

Description of what you have experienced as a major joy or a series of smaller related joys. Throughout our journeys, we can expect the road of life to be paved with many joys and sorrows. What I am about to convey to you, the reader, are a few of my joyful memories during my quarter of a century travels on this road. Some of you will be able to empathize with what I say and relate to the same general feelings. Others will not relate to my own specific events but instead recall their own. As human beings, we can relate to the same subject of joy and sorrow.My earliest, joyful childhood memory is that of my grandmother and the times we spent with one another. I had to have been about seven years old. At that age my grandmother meant the world to me. I remember her taking me on "secret" walks with her on her farm. These special adventures were reserved just for me.GrandparentsWe would go to her meadow of wild flowers on warm and sunny days, lay down a big comfy blanket, and have a picnic fit for royalty. She would always go out of her way to make our special retreats in this p lace magical. She would pack her best plates and crystal water goblets in her large wicker picnic basket, along with all the foods and beverages we jointly enjoyed. She and I would make our way to this place on earth that was reserved solely for the two of us, all the while, her reminiscing about our shared bonds of heritage. When we would get to our lea, with its soft scents of honeydew dancing around our noses, we would feast on our picnic. During our banquet, we would concoct outlandish stories, each of us building off the others, most of which involved fire breathing dragons and damsels...

Nucleation Definition (Chemistry and Physics)

Nucleation Definition (Chemistry and Physics) NucleationDefinition Nucleation is the process where droplets of liquid can condense from a vapor, or bubbles of gas can form in a boiling liquid. Nucleation can also occur in crystal solution to grow new crystals. It is seen in gases when tiny bubbles coalesce into larger ones. In general, nucleation is a self-organizing process that leads to a new thermodynamic phase or a self-assembled structure. Nucleation is affected by the level of impurities in a system, which can provide surfaces to support assembly. In heterogeneous nucleation, organization begins at nucleation points on surfaces. In homogeneous nucleation, organization occurs away from a surface. For example, sugar crystals growing on a string is an example of heterogeneous nucleation. Another example is the crystallization of a snowflake around a dust particle. An example of homogeneous nucleation is growth of crystals in a solution rather than a container wall. Examples of Nucleation Dust and pollutants provide nucleation sites for water vapor in the atmosphere to form clouds.Seed crystals provide nucleation sites for crystal growing.In the Diet Coke and Mentos eruption, the Mentos candies offer nucleation sites for the formation of carbon dioxide bubbles.If you place your finger in a glass of soda, carbon dioxide bubbles will nucleate around it. Carbon dioxide bubbles nucleating on a finger. Arie Melamed-Katz Sources Pruppacher, H. R.; Klett J. D. (1997). Microphysics of Clouds and Precipitation.Sear, R.P. (2007). Nucleation: theory and applications to protein solutions and colloidal suspensions (PDF). Journal of Physics: Condensed Matter. 19 (3): 033101. doi:10.1088/0953-8984/19/3/033101

Discuss the challenges and benefits involved in using a health Essay - 1

Discuss the challenges and benefits involved in using a health promotion approach to tackle the levels of depression experienced within the general population - Essay Example This has been majorly attributed to the fact that research undertaken among these professionals to facilitate the understanding of mental health issues differ with regard to the methodologies, theories and language used to undertake the study. Stakeholders such as psychologist, sociologists, non-governmental organizations and governments have developed and implemented various approaches directed towards reducing various health challenges that arise due to cognitive problems. The level of efficacy among these approaches differs to a great extent; however, some of these challenges have shown a great level of relationship. Another most obvious characteristic of these challenges is the fact that they have benefits and to some extent demerits. This discussion will focus on the various approaches that are used to promote mental health among different populace and their associated challenges as well as benefits, specifically those that are applied towards reducing problems caused by depression. Depression one of the most common mental health challenges that are in the contemporary society. Most psychologists have described depression as disorder that affects an individual’s moods by causing continuous feelings of sadness as well as loss of interests in various human activities (Aguirre, 2008). In addition, depression has been cited as mental health challenge that can also affect an individual’s physical capacities and emotions by creating variation in an individual’s mode of thinking and behavior (Aguirre, 2008). One of the most common approach to addressing various levels of depression as a mental health challenge is the application of the Public Health Approach. Specifically, this approach involves the application of medical and psychological strategies geared towards changing the behaviors, lifestyles and coping mechanisms to challenges caused by depression. Public health approaches are closely related with the reduction of depression as a major

Music as a Means of Expressing Identity and Change in the Music Essay

Music as a Means of Expressing Identity and Change in the Music Industry - Essay Example The message conveyed in the music was not necessary false, but it was exaggerated in some manner (Whitfield). A typical example is L. Wolfe Gilbert who depicted â€Å"The levee, in old Alabammy†. It should be noted that the state is one hundred and fifty miles east of any levees. L. Wolfe Gilbert had some knowledge about the Black Sea because he was born in Ukraine, but he had no knowledge of the Mississippi River. Therefore, singing about the levee when he had no knowledge of any levee was a way of presenting imagination as truth, through music. Those who knew the levees, listened to his music, and identified with it, expressing their identity, a form of forgery it was. Another example of false reality is George Gershwin’s biggest hit, â€Å"Swanee† (Whitfield). The musician, George Gershwin, presented in his music, information about the Suwannee River as a reality, but this was a forged reality. This is because George Gershwin and his lyricist visited the Suwan nee River, only after their song had become so famous in the nation. This means that the two had no first hand experience or practical information about the Suwannee River, but they fantasised the information they sang about the river (Whitfield). That is why, during their visit to the river, they found the location not as impressive as expected, and were shocked on knowing the reality. Whoever who listened to the song, thinking that the artists knew the reality about what they were singing forged whatever the identity that s/he expressed about who s/he is. Nora Bayes produced soothing and famous hits such as ‘Shine On and Harvest Moon, but her song’s composer, Harry Von Tilzer was not a husbandman (Whitfield). The songs were used by listeners... This "Music as a Means of Expressing Identity and Change in the Music Industry" essay outlines interesting point of view on the music and purposes in which people use it. Also, it researches the music of the history and its development. The music industry has gone through several cycles of corporate consolidation and diversification since the late 19th century. Often these swings occurred in response to technological innovations or legal proceedings. There various moments of change that music has passed through, and such moments have had some effects on the sound of popular music. One such moment was the period when live performances lost their role in music. Initially, musicians performed their music live in clubs. The loss of the role of live performances in music led to led to the split of music genres. As a result, the use of discos where music was played in clubs became common. For instance, the Beatles made rock to be the most popular concert and album of their time (Wald). The making of rock the most popular concert and music of this time had a positive effect on the sound of popular music. There was more respect for popular music, as a result of this. It should also be noted that jazz music attained a widespread respectability as well, only after it had ceased to be a mainstream pop style. This is because he artists had capitalised on technological advancements to alter the beats of popular music. Later, due to technological advancements, rock music was separated from its rhythmic and cultural roots.