Tuesday, March 29, 2011
Discovering Disease
On page 198, Shubin discusses a method employed by European scientists to study a mitochondrial disease. The team studied a microbe known as Paracoccus denitrificans and were able to create the same human mitochondrial disease in the bacterium by changing certain genes. How might this method, using evolutionary history to identify genetic mutations that cause disease, be further expanded and applied to other aspects and characteristics of human life, even beyond disease? Would it be useful? Why or why not? vickram.pradhan@yahoo.com Vickram Pradhan 1/2a
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This process might be used to study characteristics of human life, like genetic mutations and diseases, by using organisms that share certain features with humans instead of actual humans for research. Once we understand the relationship between ourselves and other organisms, we can determine which creatures make for a good human analog in which respects. Once a model organism is found, it can be much easier, faster, more effective, and more ethical to use that organism to research aspects of human life than to use humans (http://www.fishforscience.com/model-organisms/model-organisms).
ReplyDeleteA general, traditional model organism for this type of research is rats, hence the term “lab rat.” Rats and mice have many developmental similarities to humans, and they have been used in research on many types of diseases and disorders. To perform these experiments, like the one on Paracoccus denitrificans by changing their genes, “Transgenic mice result from genetically altered embryos: a gene or combination of genes is microinjected into developing oocytes. The genetic alteration affects the germ plasm, and subsequently can be transmitted to progeny” (http://www.vetmed.ucdavis.edu/Animal_alternatives/cancer.htm). In this way, human diseases like cancer and Parkinson’s Disease can be researched and hopefully cured through experiments on other organisms.
The use of model organisms for human research is not limited to diseases, though. Scientists at John Hopkins were able to introduce a gene into mice in 2007 that allowed the mice to have a much broader range of color vision than they would normally have (http://www.colormatters.com/vision_mice.html). This research can aid our understanding of how human color vision functions and develops. Creating this type of artificial alteration to otherwise naturally occurring mutations that cause change and ultimately evolution over time can allow for specific observation of known genetic changes, generating a better picture of how genetics are linked to physiological development.
By understanding the connections between humans and other organisms, we can gain a greater knowledge of our own bodies and, hopefully, find cures to some of our most detrimental diseases.
- Vincent Fiorentini
(vincent@panatechcomputer.com)
Vince did a great job on answering this and because of that, there is not much else to answer from the question. But I would like to elaborate on Vince’s response further, especially on model organisms and the ethical issues that come with it.
ReplyDeleteModel organisms have always been used to explore different diseases and treatments for humans. These animals have special characteristics that make them either very accessible, or very easy to be used to reach the objective of the experiment. Some of these characteristics include short life-cycles, techniques for genetic manipulation like stem cell lines, methods of transformation, inbred strains etc., and non-specialist living requirements. Scientists also look for the size and generation time of the organism, and the potential economic benefit of the experiment. Some of the most common model organisms include E. coli, Yeasts, fruit flies, and the African clawed frog. Each of these has their own “specialties” when it comes to experiment types. For example, E.coli is the most widely used organism in molecular genetics. Another example is how fruit flies can be raised easily in a lab, mutations are easily induced and usually observable, and they have rapid generations which is why they are used as test subjects for molecular genetics, population genetics, and developmental biology.
(http://ceolas.org/VL/mo/)
But one of the most recent and impressive model organisms is the zebrafish. These small vertebrates are better than mice in some ways because they are cheaper and easier to handle, as well as the fact that they have a transparent and readily accessible embryo for developmental biology work. Presently, the zebrafish is being used in a project researching its possible effectiveness as a cancer model system. This is mostly due to its transparent embryos which allow for rapid screening and experimental manipulation. Although the necessary research is still being done to determine if the zebrafish is a better alternative to mice, the future does look promising according to James F. Amatruda of the Howard Hughes Medical Institute: “The magnitude of the challenges facing zebrafish cancer research is matched by the great promise of the system to discover novel cancer genes, to probe the interactions among these genes, and to identify chemotherapeutic and chemopreventive agents in the context of a living, vertebrate organism”.
http://www.peds.swmed.edu/utsw/facdir/cma/fileuploads/7/facdir73954/CancerCell2002.pdf
With all this talk about model organisms, many people forget about what is actually being done to these animals. The ethical battle between scientists and animal rights activists has existed since the beginning and has caused many problems for scientist when it comes to publishing their findings. Animal rights activists have two main arguments against animal lab testing: the deontological argument and the utilitarian argument. The deontological argument consists of how human benefit should not be derived from animal suffering from a moral standpoint. The utilitarian argument questions the basis for animal use and challenges the reliability of treatment strategies based on the study of other species and the validity of animal models. Many scientists counter these arguments with the question, “How is it possible to develop technology without it?” or “Do you want to be the test subject?”. The two sides of this argument are very biased and because of this, the ethical battle about lab testing of model organisms may never end.
http://www.stats.ox.ac.uk/__data/assets/pdf_file/0017/4607/Blakemore.pdf
Matt Micucci (coochqbk@sbcglobal.net)