Animal testing on invertebrates

Most animal testing involves invertebrates, especially "Drosophila melanogaster", a fruit fly, and "Caenorhabditis elegans", a nematode. These animals offer scientists many advantages over vertebrates, including their short life cycle, simple anatomy and the ease with which large numbers of individuals may be studied. Invertebrates are often extremely cost-effective, as thousands of flies or nematodes can be housed in a single room.

With the exception of some cephalopods, invertebrate species are not protected under most animal research legislation, and therefore the total number of invertebrates used remains unknown.

Main uses

Research on invertebrates is the foundation for current understanding of the genetics of animal development. "C. elegans" is especially valuable as the precise lineage of all the organism's 959 cells is known, giving a complete picture of how this organism goes from a single cell in a fertilized egg, to an adult animal. The genome of this nematode has also been fully sequenced and any one of these genes can easily be inactivated through RNA interference, by feeding the worms antisense RNA. [cite journal |author=Lee J, Nam S, Hwang SB, "et al" |title=Functional genomic approaches using the nematode Caenorhabditis elegans as a model system |journal=J. Biochem. Mol. Biol. |volume=37 |issue=1 |pages=107–13 |year=2004 |pmid=14761308 |url=http://www.jbmb.or.kr/fulltext/jbmb/view.php?vol=37&page=107] A major success in the work on "C. elegans" was the discovery that particular cells are programed to die during development, leading to the discovery that programed cell death is an active process under genetic control. [cite journal |author=McCarthy JV |title=Apoptosis and development |journal=Essays Biochem. |volume=39 |issue= |pages=11–24 |year=2003 |pmid=14585071] The simple nervous system of this nematode allows the effects of genetics on the development of nerves to be studied in detail. [cite journal |author=Seifert M, Schmidt E, Baumeister R |title=The genetics of synapse formation and function in Caenorhabditis elegans |journal=Cell Tissue Res. |volume=326 |issue=2 |pages=273–85 |year=2006 |pmid=16896949 |doi=10.1007/s00441-006-0277-2] However, the lack of an adaptive immune system and its simple organs prevents "C. elegans" being used in medical research such as vaccine development.cite journal |author=Schulenburg H, Kurz CL, Ewbank JJ |title=Evolution of the innate immune system: the worm perspective |journal=Immunol. Rev. |volume=198 |issue= |pages=36–58 |year=2004 |pmid=15199953 |doi=10.1111/j.0105-2896.2004.0125.x]

The fly "D. melanogaster" is the most widely-used animal in genetic studies. This comes from the simplicity of breeding and housing the flies, which allows large numbers to be used in experiments. Molecular biology is relatively simple in these organisms and a huge variety of mutant and genetically-modified flies have been developed. [cite journal |author=Dietzl G, Chen D, Schnorrer F, "et al" |title=A genome-wide transgenic RNAi library for conditional gene inactivation in Drosophila |journal=Nature |volume=448 |issue=7150 |pages=151–6 |year=2007 |pmid=17625558 |doi=10.1038/nature05954] Fly genetics has been vital in the study of development, the cell cycle, behavior, and neuroscience. The similarities in the basic biochemistry of all animals allows flies to be used as simple systems to investigate the genetics of conditions such as heart disease and neurodegenerative disease. [cite journal |author=Marsh JL, Thompson LM |title=Can flies help humans treat neurodegenerative diseases? |journal=Bioessays |volume=26 |issue=5 |pages=485–96 |year=2004 |pmid=15112229 |doi=10.1002/bies.20029] [cite journal |author=Bier E, Bodmer R |title=Drosophila, an emerging model for cardiac disease |journal=Gene |volume=342 |issue=1 |pages=1–11 |year=2004 |pmid=15527959 |doi=10.1016/j.gene.2004.07.018] However, like nematodes, "D. melanogaster" is not widely used in applied medical research, as the fly immune system differs greatly from that found in humans, [cite journal |author=Leclerc V, Reichhart JM |title=The immune response of Drosophila melanogaster |journal=Immunol. Rev. |volume=198 |issue= |pages=59–71 |year=2004 |pmid=15199954 |doi=10.1111/j.0105-2896.2004.0130.x] and diseases in flies can be very different from diseases in humans. [cite journal |author=Mylonakis E, Aballay A |title=Worms and flies as genetically tractable animal models to study host-pathogen interactions |journal=Infect. Immun. |volume=73 |issue=7 |pages=3833–41 |year=2005 |pmid=15972468 |url=http://iai.asm.org/cgi/content/full/73/7/3833?view=long&pmid=15972468 |doi=10.1128/IAI.73.7.3833-3841.2005]

ee also

*Animal testing on non-human primates
*Animal testing on rodents
*Testing cosmetics on animals

References

Further reading

General
*Lawrence PA. "The Making of a Fly: The Genetics of Animal Design." Blackwell Publishing Limited (March 1, 1992) ISBN 0-632-03048-8
*Demerec M. "Biology of Drosophila" Macmillan Pub Co (January 2000) ISBN 0-028-43870-1
*Hall, DH. "C. Elegans Atlas" Cold Spring Harbor Laboratory Press (November 30, 2007) ISBN 0-879-69715-6

Practical
*Goldstein LSB, (Ed) Fryberg EA. "Methods in Cell Biology: Drosophila Melanogaster : Practical Uses in Cell and Molecular Biology" Academic Press (January 1995) ISBN 0-125-64145-1
*Epstein HF, (Ed), Shakes DC. "Methods in Cell Biology: Caenorhabditis Elegans : Modern Biological Analysis of an Organism" Academic Press (October 1995) ISBN 0-122-40545-5

External links

* [http://flybase.net/ FlyBase] Main "Drosophila" research database.
* [http://www.wormbase.org/ WormBase] Main "C. elegans" research database.