DNA Methylation: Basic Mechanisms

2 On the Early History of 5-mC In the fall of 1966, Norton D. Zinder of Rockefeller University in New York City presented the Harvey Lecture on "Phage RNA as Genetic Material" (Zinder 1966). Frankly,I do not remember manydetailsofhis talk. However, one ofhis concluding remarks, in which he thanked his teacher Rollin Hotchkiss, stuck in my mind andbecame an important leitmotiffor much of my own scienti?c career. Norton's relevant passages went somethinglikethis (approximate quotation): When we hope to have made a scienti?c discovery, we better spend much of our time immediately after this fortunate event in trying to counter our own beliefsand interpretations. Onlyafter a lot of painstaking scrutiny involving many control experiments when our discoveryhas stood the test of careful consideration, can one hope that our colleagues will beabletocon?rm the new ?ndings. Of course, it is a major task of the scienti?c community to respectfully meet supposedly novel announ- ments withdisbelief and skepticism and in turn commence the process of disproving these concepts. Consistent con?rmations, with plenty of modi?cations to be sure, will providethe encouragement necessary to continue and to improve the initial observations and conclusions.Apparently, the scienti?c tradition re?ected in this overall cautious attitude had emanatedfrom the laboratory of Oswald Avery that Rollin Hotchkiss had been trained in. This certainly most important of scienti?ccredos seems tocontradict intuitively held notions and might bethought to run counter to general practice.