The term "epigenetics" was introduced in 1942 by embryologist Conrad Waddington, who, relating it to the 17th century concept of "epigenesis", defined it as the complex of developmental processes between the genotype and phenotype. While in the years that followed, these processes - in particular gene regulation - were tackled, not in the frame of epigenetics but of genetics, research labelled "epigenetics" rose strongly only in the 21st century. Then it consisted of research on chromatin modifications, i.e. chemical modifications of DNA or histone proteins around DNA that do not change the base sequence. This rise was accompanied by far-reaching claims, such as that epigenetics provides a mechanism for "Lamarckian" inheritance. This article highlights the origin of epigenetics, the major phases of epigenetic research, and the changes in the meaning of the term. It also calls into question some of the far-reaching claims that have accompanied the recent rise of epigenetics.

SummaryThis historical review highlights the life and research of Leonor Michaelis, the German-Jewish-American pioneer in enzyme kinetics and the physical chemistry of proteins. Based on an overview of early research on enzyme kinetics, the outstanding achievements of Michaelis and his research fellow Maud Menten (i.e. their mathematical derivation of the fundamental kinetic rate law and the corresponding affinity constant of the enzyme-substrate bond) are highlighted and discussed. The background and consequences of Michaelis's marginalization in German academia and, finally, his emi- gration from Germany (already prior to the advent of Nazism) are analysed. An examination of Michaelis's major work in the field of biological redox reactions in New York and a general assessment of Michaelis as a researcher conclude this part of the review. IntroductionOn 3 December 2011, a ceremony was organized by the Department of Biology of Humboldt University of Berlin to mark the change of name of one of its buildings from Abderhalden Haus to Leonor Michaelis Haus (Fig. 1) This decision was taken after the questionable nature of major parts of Emil Abderhalden's research had come to light (see below). The renaming of the institute after Leonor Michaelis is of dual significance: first, it is a powerful reminder of Leonor Michaelis's seminal and far-reaching research in Berlin around a century ago, which is part of the topic of this special issue; it also draws attention to the lack of acknowledgement he received while in Germany, as a consequence of which he left the country in 1922. Second, as was realized immediately by the young researchers who participated in the renaming ceremony (one of the authors of the present review, UD, participated in the event, with a lecture on Michaelis), it provides Humboldt University's Department of Biology with the role model of an outstanding, internationally renowned researcher whose work has remained fertile to this day, and also of an exceptional human being (Fig. 2).We review Michaelis's life and research, with special emphasis on his work in Berlin. Throughout his life, Michaelis successfully dealt with a variety of different topics, which included experimental embryology, the physical chemistry of proteins, immunology, and biological redox reactions. In addition, he wrote several textbooks on subjects such as embryology [1] and mathematics for biologists and medical students [2]. Here, we focus on his ground-breaking work on the physical chemistry of proteins and enzymes, which culminated in his famous mathematical derivation, together with Maud Menten, of the fundamental kinetic rate law and the corresponding affinity constant of the enzyme-substrate complex. In addition, we review Michaelis's disclosure of the fraudulent nature of Abderhalden's work and its consequences. An examination of Michaelis's major work in the field of biological redox reactions in New York and a general assessment of him as a researcher conclude this part of the review.Leonor Michaelis in Berlin: his emig...

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Chemie und Biochemie in Deutschland waren von der Entlassung und Emigration jüdischer Wissenschaftler in besonderem Maße betroffen. Diese Verjagung jüdischer Wissenschaftler trug insbesondere in der Biochemie, der Physikalischen Chemie und der Quantenchemie zu einem nach 1945 deutlich werdenden starken Rückgang der internationalen Bedeutung deutscher Wissenschaft bei. Nichtemigrierte Wissenschaftler paßten sich nach 1933, von einigen Ausnahmen abgesehen, in den meisten Fällen schnell an die neuen politischen Verhältnisse an. Eine Reihe von ihnen unterstützte die Politik der Nationalsozialisten sogar aktiv. Diese Tatsache sowie die nach dem Krieg verbreitete Haltung des „Vergessens“ der zwölf Jahre nationalsozialistischer Herrschaft erschwerten den internationalen wissenschaftlichen Austausch nach 1945 und verzögerten dadurch den Anschluß der zurückgefallenen Forschungsgebiete an das internationale Forschungsniveau.