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Johan Friedrich Miescher (13 August 1844, Basel - 26 August 1895, Davos) was a Swiss biologist. He isolated various phosphate-rich chemicals, which he called nuclein (now nucleic acids), from the nuclei of white blood cells in 1869 at Felix Hoppe-Seyler's laboratory at the University of Tübingen, Germany, paving the way for the identification of DNA as the carrier of inheritance. The significance of the discovery, first published in 1871, was not at first apparent, and it was Albrecht Kossel who made the initial inquiries into its chemical structure.
Miescher came from a scientific family: his father and his uncle held the chair of anatomy at the University of Basel. As a boy he was shy but intelligent. He had a partial hearing impairment due to a severe attack of typhus. But this did not stop him from having an interest in music and his father performed publicly. Miescher himself studied medicine at Basel. In the summer of 1865 Friedrich worked for the organic chemist Adolf Stecker in Goettingen. His studies were interrupted for the year when he became ill with typhoid fever; however, he still received his M.D. in 1868.
Miescher felt that his partial deafness would be a disadvantage as a doctor so he turned to physiological chemistry. Miescher originally wanted to study lymphocytes but was encouraged by Felix Hoppe-Seyler to study leucocytes. Miescher was interested in studying the chemistry of the nucleus. Lymphocytes were difficult to obtain in sufficient enough numbers to study while leucocytes were known to be the one of the main components in pus and could be obtained from bandages at the nearby hospital. The problem was, however, washing the cells off the bandages without damaging them.
Miescher devised different salt solutions eventually producing one with sodium sulphate. The cells were filtered. Since centrifuges were not present at this time the cells were allowed to settle at the bottom of a beaker. He then tried to isolate the nuclei free of cytoplasm. He subjected the purified nuclei to an alkaline extraction followed by acidification resulting in a precipitate being formed which Miescher called nuclein (now known as DNA). He found that this contained phosphorus, nitrogen, and sulfur. The discovery was so unlike anything else at the time that Hoppe-Seyler repeated all Miescher's research himself before publishing it in his journal. Friedrich then went on to study physiology at Leipzig in the laboratory of Carl Ludwig for a year before returning to Basel where he was appointed professor of physiology.
Miescher and his students researched much of the nucleic acid chemistry but their function remained unknown. However, his discovery played an important part in the identification of nucleic acids as the carriers of inheritance. The importance of Miescher's discovery was not apparent until Albrecht Kossel (a German physiologist specializing in the physiological chemistry of the cell and its nucleus and of proteins) carried out research on the chemical structure of nuclein. Friedrich Miescher is also known for demonstrating that carbon dioxide concentrations in blood regulate breathing.
He died of tuberculosis in 1895 aged 51. He has had a laboratory of the Max Planck Society in Tübingen and a research institute in Basel named after him.
|This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Friedrich_Miescher". A list of authors is available in Wikipedia.|