Shenk argues that the widespread publicity of gene manipulation such as gene splicing, cloning, etc. has given the public an inaccurate view of "genetic understanding and genetic reality. The public has gotten the impression that the answer to almost every question about our health and well-being can be found in our genome" (180). He is essentially arguing that too much focus is being placed on genetic advances' power to influence human achievement. However, he also states in the argument that "we have far more control over our genes...than we think" (115) and advocates our potential to utilize our environment to use gene expression to our benefit. To what extent can we manipulate our genes to our advantage? In GxE, since Shenk argues that we have little control over our environment, is it possible to maximize our control over G? Or is that too closely tied to environment?
Vivian Wang (vivian.wang9895@gmail.com)
With the discovery of epigenetics, the control we have over our genes and the genes of future generations has changed drastically. Acting as a “mediator for gene expression” (159), the epigenome protects the DNA and regulates when certain genes are expressed and how they are expressed. Like DNA, epigenetic material is inherited, so manipulating genes starts with the choices and environment of past generations. Choices such as smoking and overeating have been proven to alter epigenetic marks, allowing certain genes to be over expressed while other “good” genes are not expressed as well. These marks are passed on to further generations, limiting the lifespan of children even before conception. These discoveries have put an emphasis on the importance of gene expression rather than the actual genes themselves. An experiment was done by Randy Jirtle, an oncologist from Duke University, to prove this. Pregnant mice with a regulated agouti gene, which gives them yellow coats and a better chance of being obese and diabetic, were used. Jirtle fed one group a diet high in B vitamins and one group a normal diet. The B vitamins caused more methyl groups to be available for attachment to the gene, causing DNA methylation and ultimately changing the expression of the gene. The group of mice receiving a B vitamin-rich diet gave birth to brown, normal-sized pups even though the agouti gene was present (http://www.time.com/time/magazine/article/0,9171,1952313-2,00.html). With this knowledge, we can manipulate the expression of our genes to our advantage. As further research is done, knowing what factors in our environment cause these changes in epigenetic marks can allow us to potentially manipulate the way genes are expressed in generations to come. Changing our environment, however is harder than it seems. Shenk states, “Even in a land of free choice, we are mostly shaped by habits, messages, schedules, expectations, social infrastructure, and natural surroundings that are not exclusively our own. Many of these elements are passed down from generation to generation with little or no change and are difficult or impossible to alter” (118-119). With our environment and genes being so connected in the GxE model it may seem difficult to manipulate anything with the environment seeming to be so difficult to change. This proves that we do not have complete control over what we can accomplish, but with the new knowledge of the GxE model, we can begin to take more control with the right steps. The only way we can maximize our control over genes is by controlling alterations to epigenetic material, which can be done by controlling our environment and choices. Though the environment is difficult to change, genes cannot be manipulated without environmental alterations.
ReplyDeleteJenna Sherman (jsherm013@aol.com)
In recent times, as a result of epigenetics, the notion of genetic engineering has taken off. Logically, many people initially thought that if you can control your environment, which epigenetics now tells us can influence gene expression, then you can control your genes. While this may be true to some degree, in reality “there is no escaping basic human biology” (Shenk 56). In terms of maximizing our control over our genes, as of right now humans are limited. This is because “one of the first genetic engineering experiments was conducted by Stanley Cohen and Herbert Boyer in 1973” (http://highered.mcgraw-hill.com/olcweb/cgi/pluginpop.cgi?it=swf::535::535::/sites/dl/free/0072437316/120078/bio38.swf::Early%20Genetic%20Engineering%20Experiment). From that point on, although science has been progressing at an unprecedented rate, human genetic advancements have not been stabilized. So all in all, genetic engineering is not a possibility as of right now. However, if we look at the definition of evolution, which is “the result of the interactions between organisms and their current environments” (Campbell 531), then we can see that in theory, if one manipulates his or her environment over an extended period of time, then one can maximize his or her manipulation of his or her genes. But in reality, a person as Shenk states, has little control over his or her environment. As Shenk shows, if one is subject to a large amount of dialogue at a young age, as found in “Hart and Risley’s incontrovertible study” (Shenk 47), then his or her intelligence levels go up. Similarly, to increase intelligence levels, “reading early and often…[and] Nurturance and encouragement…[and] setting high expectations” (Shenk 47) all attribute to changes in gene expression. Now, epigenetics is unique in that it shows how near evolutionary changes can take place over time. Prions, found inside cells can change shape based on environmental conditions such as temperature or the presence of chemicals. After they change shape, these proteins can collide with other prions and cause them to change shape as well. Soon after, “When the cell divides, both daughter cells will contain prions of both states, and the chain reaction can keep occurring in that new generation” (http://newswatch.nationalgeographic.com/2010/11/11/how_evolution_is_evolving/). When the prions interact with the rest of the cell, including the DNA, the different shapes of the prions can cause different proteins to be made, or different parts of the DNA to be read which triggers different phenotypes. So essentially, “some [prions] may actually become incorporated into the DNA” (http://newswatch.nationalgeographic.com/2010/11/11/how_evolution_is_evolving/) as a result of changes in diet, exercise, or lifestyle, or changes to one’s environment. These changes will then be passed down to the next generation. As of right now, this is the closest we can get to controlling G through our environment.
ReplyDeleteAs Jenna states “The only way we can maximize our control over genes is by controlling alterations to epigenetic material, which can be done by controlling our environment and choices. Though the environment is difficult to change, genes cannot be manipulated without environmental alterations” (Jenna Sherman).