Toward the end of "The Meaning of it All," Shubin provides several examples of Nobel Prize-winning studies based on model organisms (198). Pioneering researchers have used these organisms to uncover new biological insights.
What exactly are model organisms? What are the pros and cons of using them?
Model 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.
ReplyDelete(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)
There are three major types of model organisms which Matt did not discuss. The genetic model organisms are species that are used for genetic analysis because they breed in large numbers and have a short generation time so large scale crosses can be set up and followed over several generations. Many mutants are generally available and they offer detailed genetic maps. This can include baker's yeast and the common fruit fly.
ReplyDeleteThe next type is the experimental model organism which don't have long generartion intervals but they have experimental advantages. This can include chickens and frogs which produce embryos that can easily be studied and manipulated. These species are widely used model organisms in developmental biology.
The third group consists of the genomic model organisms which occupy pivotal position in the evolutionary tree. Genes affecting more evolutionarily advanced features are less likely to have direct counterparts in simple animals. The mouse genome is similarly organised to the human genome and some blocks of genes are even arranged in the same order. This makes studies on mice very effective and it's the most widely used for the testing of new drugs.
Overall, we have three major classifications of model organisms and as stated by Matt, there are of course ethical problems with any testing. It allows us to find new drugs/cures with the tradeoff of killing/harming innocent organisms. Although I would like to think we could replace these "test dummies", I don't think it will be coming anytime soon. :(
Eryk Fundakowski- arthur2446@comcast.net
http://www.nih.gov/science/models/
http://www.wormclassroom.org/teaching-model-organisms
http://www.clfs.umd.edu/labs/mount/Models.html