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ABSTRACT The concept of chromatin as a complex of nucleic acid and proteins in the cell nucleus was developed by cytolog ists and biochemists in the late 19th century. It was the starting point for biochemical research on DNA and nuclear proteins. Although interest in chromatin declined rapidly at the beginning of the 20th century, a few decades later a new focus on chromatin emerged, which was not only related to its structure, but also to its function in gene regulatory processes in the development of higher organisms. Since the late 20th century, research on chromatin modifications has also been conducted under the label of epigenetics. This article highlights the major phases of chromatin research until the present time and introduces major investigators and their scientific and philosophical outlooks.
Eukaryotic genomes are packaged into a nucleoprotein complex known as chromatin. The term was introduced in 1879 by German cytologist Walther Flemming. While observing the processes of mitosis in a light microscope, Flemming coined the term to describe the easily stainable threads in the nucleus. He predicted that it would not have a long life: "The word chromatin may serve until its chemical nature is known, and meanwhile stands for that substance in the cell nucleus which is readily stained" (Portugal and Cohen 1977, 40). However, Flemming's prediction did not come true. Although the chemical nature of chromatin-a complex of nucleic acid and proteins-was already elucidated at the end of the 19th century, the term did not disappear, and it even became fashionable again at the end of the 20th century. But despite the fact that both its chemical structure and the structure and function of DNA have been elucidated, the exact function of chromatin has not yet been completely resolved.
Unlike the terms genes or epigenetics, which have changed their definitions rapidly over time, the definition of chromatin has remained more or less the same for more than a century. The present paper illuminates how different scientific contexts changed the relevance and meaning of this key scientific concept from the 19th century until the present time. It introduces the seminal researchers involved in chromatin research and analyzes the philosophy behind their different views.
The Rise and Decline of Chromatin Research, 1870s-1950s
The rise of...