|Latest Pusztai review published / Pusztai on GM pea study misinformation (5/12/2005)|
The latest Pusztai review has now been published:
A. Pusztai and S. Bardocz: GMO in animal nutrition: potential benefits and risks. In "Biology of Nutrition in Growing Animals", R. Mosenthin, J. Zentek and T. Zebrowska (Eds.), 2OO5. Elsevier Limited, pp. 513-54O.
Unfortunately, the book is priced at GBP145.00 but libraries may consider taking it.
You can get more information on www.elsevierhealth.com or from Louisa Welch, e-mail: [email protected]
Normally I don't bother to correct mistakes that are not in scientific texts. However, in this instance I make an exception because Dr Preston severely criticizes and ridicules Greenpeace for their mistakes.
The science qualifications of the Greenpeace GM campaigner, Jeremy Tager, are probably not up to Dr Preston's and therefore one should be less severe with him, although Jeremy Tager ought to have checked up on what is rightly or wrongly ascribed to him. However, Dr Preston has no such excuses. Although I doubt that many scientists would read his piece on this website, here is a list of scientific mistakes that he should not have made - all to be found in his relatively short piece:
Second para (lines 9-1O): Glycosylation of proteins does not occur at arginine residues. This is schoolbook stuff.
Third para (lines 5-6): Neither trypsin inhibitors (and particularly bean or pea trypsin inhibitors) nor bean alpha-amylase inhibitor belong to the prolamine superfamily. Bean alpha-amylase inhibitor is neither sulphur amino acid-rich (with just over 1% methionine) nor a small protein (its molecular weight is 6O,OOO daltons). Apart from that, what he says in this para is correct, although the last sentence cannot be construed to apply to bean/pea alpha-amylase inhibitor.
Fourth para: No careful independent studies on GM crops prior to commercialization are done! If he thinks that such studies are done, please, let us have the references. Please, do not bother us with commercial animal production studies or studies from people with affiliations or funding from the biotech industry that have not been independently confirmed. In fact, this commendable GM pea study is almost unique in this respect.
I also have to tell Dr Preston that in the close to 36,OOO distinct Phaseolus vulgaris cultivars (in Cali, Columbia) the glycosylation of their constituent alpha-amylase inhibitors is very variable, but they are probably no more allergenic than the variety examined by Prescott et al.
Thus, we would not have to consider his hypothetical experiment to find such different glycosylation patterns. The evidence provided in the paper, by the way, does not unequivocally establish that the difference in glycosylation of the alpha-amylase inhibitor is the sole or even the main reason for the allergenicity of the GM peas.
Incidentally, I told both Higgins and Chrispeels that the GM pea alpha-amylase inhibitor had different subunit and glycosylation patterns way back in 1998 but they did not seem to be unduly concerned about this. In fact, both were rather sceptical when I told them that the transgene-expressed alpha-amylase inhibitor in peas had a distinctly different structure from that in kidney beans. I ought to know because this was the very first plant glycoprotein I isolated and characterized in 1963/1964 and published in Biochem J in 1966. They brushed this aside at the time, but I see from the paper that in the best tradition of Maarten Chrispeels who used to live on the morsels of my papers and ideas, worked it out and now accepts it. Needless to say, also in the best tradition of these guys, without acknowledging this. Indeed, in the paper they managed to avoid even referring to our J. Nutrition paper, a feat even Houdini would have been proud of.