From his position as editor of Nature, Philip Campbell has provided the world with measured and intelligent leadership in biology, at a time of radical transformation in our discipline. It is puzzling that he would have chosen to side with a vociferous minority in obfuscating the reality of the contamination of one of the world's main food crops with transgenic DNA of industrial origin, (letters May 15th).

Perhaps the key lies in his tacit acknowledgement, albeit by dismissal, of the enormous pressures on anyone working in or around the biological sciences ever since we were set on a collision course with commercial interests.

He is right in pointing out that modern science should not be - and is not normally - carried out by obscurantist practices exposed by George Monbiot, (the fake persuaders May 14). But Philip Campbell's participation, however reluctant, in these practices seems to be further evidence of the insidious challenges facing open discourse in biology. Our discovery of transgenic DNA in Mexican landraces (indigenous strains),  of maize has never been seriously challenged and continues to be confirmed.  There is no legitimate reason why we should have acquiesced in Nature's insinuations for a retraction, or why Nature should have taken the unprecedented measure of unilaterally withdrawing its support for our paper, which in its own peer reviewed system recognised as valid and important.

Neither of the two letters published by Nature, purportedly showing fatal flaws in our paper, ever questioned our main discovery. All results to date from our laboratory, as well as those from independent studies using a variety of methods, continue to support our statement, (Mexico's vital gene reservoir polluted by modified maize, April 19). It is perplexing that Nature would have chosen to side with a single critic, against  the concordant indications of a tandem of independent reviewers appointed by the journal itself, and against all empirical evidence.

Science has progressed in modern times by the presentation of results which are subsequently refined or rectified by further empirical work. As Nature well knows, the self-perpetuating genetic contamination of our crops will remain as an undeniable ecological reality for others to confirm. But will we, as a society, have the independent, public infrastructure to confront this and similar challenges derived from our transformation of the biosphere?

The coordinated attempt to discredit our discoveries in the public piazza sends a chilling message to those who would dare ask important but uncomfortable questions and find their truthful answers. It is an assault on the very foundation of science.

Against those who would like to bury from public view the reality of the uncontrolled movement of transgenic DNA in the environment , I can only echo the words of Galileo: "Eppur si mouve", [And yet it moves].

Ignacio H Chapela
Berkeley, California
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