Transgenic Bt-Crops

Domain II. These loops are extruding into the solvent. The structure of CrylAa was determined from the protease-digested (or activated) form. The structures of the C-terminal half and the hrst 27 aa N-terminal residues of CrylAa remain unknown. The Cry2Aa structure was determined from the full length, undigested protein. The Cry2Aa structure revealed additional a-helices on its N-terminus. 

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Tabashnik, B. E., Yves Carriere, TimothyJ. Dennehy, Shai Morin, Marks. Sisterson, Richard T. Roush, Anthony M. Shelton, and Jian-Zhou Zhao. Insect resistance to transgenic Bt crops Lessons from the laboratory and field. Journal of Economic Entomology 96 1031. 

First commercialized in 1996, today, Bt crops are the most commonly grown transgenic crops in the world. In 2004, an estimated 200 million acres of GE crops with Bt and/or herbicide tolerance were cultivated in seventeen countries worldwide, a 20% increase over 2003. U.S. acreage accounts for 59% of this amount followed by Argentina (20%), Canada and Brazil (6% each), and China (5%) (Fernandez-Cornejo and Caswell 2006). 

Letourneau, D.K., Robinson, G.S. and Hagen, J.A. 2003. Bt crops predicting effects of escaped transgenes on the fitness of wild plants and their herbivores. Environ. Biosafety Res. 2 219-246. 

The use of genetically modified corn and cotton has increased over 10-fold from 1992 to 1999 and as of 2002, 50 crop species have been evaluated for uses by the US Food and Drug Administration (FDA). In the development of transgenic crops, genes isolated from several varieties of the bacterium. Bacillus thuringienses (Bt) are probably the best known and most often cited example of GMO development. 

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