Today, the concepts of "genetics" and "DNA" in our minds are inseparable. And surely many will recall the names of Watson and Crick when mentioning the spiral structure of this foundation of our heredity. But not everyone knows that deoxyribonucleic acid (DNA) itself was not discovered by them at all, and it was not always the main molecule of life. Who discovered DNA, what is its significance and other aspects is the topic of this article.
Cold castle
In the laboratory where Friedrich Miescher worked, there was little light and it was very cold. After all, it was equipped in the castle of Hoetubingen of the Duke of Württemberg (Tübingen, Germany). It was the low temperature that became a fortunate combination of circumstances that made it possible in 1869 to make a discovery, which was later called one of the largest events of the XIX-XX centuries in the science of genetics. Today, a museum exhibit operates in this castle, and that very kitchen is called the “Cradle of Biochemistry”. Who discovered the DNA and what came before it?
Random biochemist
Johann Friedrich Mischer (1844-1895) was born into a family of hereditary doctors in the Swiss city of Basel. In the same place, the 23-year-old Friedrich graduated from the medical faculty of the university. But, contrary to family expectations, he did not become a doctor. He was exclusively interested in living cells and the processes that take place in them. And the young scientist was in the same laboratory in the company of forty such innovators who, under the supervision of the founder of biochemistry Felix Hoppe-Zeiler (1825-1895) studied human blood cells. It was one of the first, at that time the only biochemical laboratory in Europe, which was founded in 1818 by an outstanding chemist who gave the name hemoglobin and blood carboxyhemoglobin.
Strange sediment
The story of the discovery of DNA is very interesting. Young Friedrich Mischer got to study white blood cells (white blood cells). They brought blood bandages and pus from a local hospital, which he washed and examined the white blood cell proteins. It was then that he noticed that in the test tubes after the isolation of proteins there always remained some kind of white precipitate in the form of flakes. Studying his find under the microscope, Micher noticed that after washing, only the nucleus remained from the white blood cells. The conclusion was obvious: the substance is in the core. That's who discovered the DNA, he only called the substance nuclein (from the Latin word nucleus - nucleus).
Inquisitive researcher
The scientist changed the methods of leukocyte washing, reagents and cleaning methods. It turned out that this substance is neither protein nor fat. Biochemistry was only in its infancy, chemical analysis was a difficult, long and very laborious affair. But Friedrich Mischer conducted it and found out that the components of DNA are carbon, oxygen and nitrogen. But what is more strange - phosphorus was present in the substance in high concentrations. At that time, chemistry did not know compounds of a similar composition, and Misher realized that he had discovered something special. Goppe-Zeiler (mentor) supported him, and in 1871 the works were published and were accompanied by a review of a respected chemist of that time. Further study revealed the acidic properties of the substance, and it was then that it became known as nucleic acid. Although, in truth, the discoverer did not like this, and in his works he continued to call DNA nuclein.
Fishing for science
Returning to Basel, and taking the post of head of the department of physiology at the university where he studied, Mischer continued his scientific research. He chose salmon milk as the object for studying DNA. By the way, even today salmon milk is used to obtain DNA in large quantities. In the Rhine, salmon was abundant in those days, and Friedrich combined a pleasant pastime with a fishing rod and work on the extraction of material for research. In his works on milk (1874), he did not even suggest the role of DNA in the inheritance of traits, but rather linked this substance to fertilization processes. From studying salmon milk, he went on to study their physiology.
Later, the scientist began to study the healthy diet for prison inmates. He even wrote a cookbook. Then he founded the Institute of Anatomy and Physiology (Basel), contributed to the study of the role of blood cells in respiration. And about his nucleotide for a long time forgotten.
The collapse of the protein theory of heredity
In the XIX century, the theory was dominated in science that proteins are the material carriers of hereditary information . The role of such a simple substance as DNA in this issue was not guessed. And only in 1944 they remembered the discovery of Misher. Another physician, an American, Oswald Avery (1877-1955) showed the genetic significance of DNA with his experiments. The experiments of Avery and his co-authors Colin MacLeod and Maclean McCarthy at the Rockefeller Institute for Medical Research (New York) have clearly demonstrated that it is DNA, not proteins, that carry genetic information.
From millennia to tens of years
Science needed millennia to understand the basis of heredity. But to decipher the DNA molecule, the mechanisms of matrix synthesis and the construction of the genomic map, it took only tens of years. The experiments that F. Griffith (1928) began were continued not only by Avery et al. Molecular biology was born at the time of introducing the world to a model of the structure of DNA - a double twisted helix (1953). The names of the authors of this model are James Watson and Francis Crick, who received the Nobel Prize for their howl DNA structure model. Who discovered the substance itself and investigated it, many sources are simply silent.
Tragedies and Fates
In the history of the discovery of DNA, there are many secrets, mysteries and offended scientists. For example, Erwin Charguff (1905-2002) until his death believed that Watson and Crick stole his Nobel Prize. And although he became famous for his rules (the rules of Chargeff or the complementarity of nucleotides in the DNA chain), he called Watson and Crick nothing more than charlatans. Another mystery and tragedy is associated with the name of Rosalyn Franklin (1920-1958) - an English biologist. It was her work on X-ray diffraction analysis of nucleic acids that Watson Crick showed when they came up with the idea of a double helix.
Summarize
The discovery of deoxyribonucleic acid, its composition and structure not only gave impetus to the movement of human thought. These discoveries transferred scientific theory to the field of specific experiments and practical applications. Today we decoded the human genome, found ways to identify hereditary pathological diseases of the fetus during fetal development, and learned how to determine the relationship and the perpetrators of crimes by DNA analysis. We got the opportunity to grow tomatoes with cold-tolerance genes for salmon, multi-colored pines that change color when interacting with pollutants, and (it’s impossible not to mention proto) to grow luminous piglets.
With the discovery of deoxyribonucleic acid, fantasists' dreams of immortality and the modernization of mankind cease to be a fairy tale, but only go to the plane of time. But all this happened due to the fact that Johann Friedrich Mischer continued his work in the laboratory, despite his frozen hands.