From Mendel to epigenetics: History of genetics

In the paper

“In reality, there is no consensus about the definition of epigenetics. This is why the ‘Epigenomics Mapping Consortium’ of NIH (National Institutes of Health, USA) recently defined epigenetics in order to give room to both heritable and non-heritable changes”

What the sources say

• Not checked yetcites [20] [20] ‘Roadmap Epigenomics Project’ ‘Overview’, 2010 http://www.roadmapepigenomics.org/

In the paper

“on the occasion of the third International Conference on Plant hybridization, Bateson proposed that the new science of heredity based on Mendel's laws be named ‘genetics’. This proposal was enthusiastically approved”

In the paper

“As early as 1902, Walter Sutton and Theodor Boveri proposed to consider the chromosomes as the bearers of the Mendelian factors. They rightly thought that the process of meiosis, that is to say the two successive cell divisions leading from a diploid cell to the four haploid cells that generate the gametes, was the basis for Mendel's laws of segregation and reassortment”

In the paper

“Mendel's experimental work on peas was crucial, but only in a methodological sense. Mendel's intention was not to offer general laws of heredity, but only a ‘law of the development of hybrids’ in plants”

In the paper

“This book also introduced a technical vocabulary that rapidly became indispensable for all Mendelians: ‘allelomorph’ (or, more simply, ‘allele’), ‘homozygote’, and ‘heterozygote’; these terms imply that for a given character transmitted in a Mendelian way, each individual has two (and exactly two) physical versions of the same hereditary element — an idea that Mendel did not suggest”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites [2] [2] Bateson, W. A Defence of Mendel's Principles of Heredity, Cambridge University Press, Cambridge, UK, 1902

In the paper

“In a letter to his colleague Adam Sedgwick in 1905, the English biologist William Bateson (1861–1926) used the word ‘genetics’ to designate ‘the science of heredity and variation’.”

In the paper

“In the context of chromosomal genetics, a gene is also a unit of recombination (intra-chromosomal recombination resulting from crossing-overs). And finally, Muller's X-ray induced mutagenesis experiments introduced the notion that a gene is a unit of mutation. Remarkably, these three notions coexisted harmoniously (or almost) until the discovery that genes are made of DNA.”

In the paper

“In 1915 this led him to publish, with three other colleagues, all of whom became major geneticists, what is probably the most important book in the entire history of genetics, The Mechanism of Mendelian Heredity [7].”

What the sources say

• ?Not checked — no full text of the sourcecites [7] [7] Morgan, T.H.; Sturtevant, A.H.; Muller, H.J.; Bridges, C.B. The Mechanism of Mendelian Heredity, Henry Holt, New York, 1915 (Trad. fr. Le mécanisme de l’hérédité mendélienne. Lamertin, Bruxelles) source

In the paper

“The common feature of these changes is their stability, but this stability is more or less pronounced: some epigenetic modifications are transmissible from one generation to another while others are not. Some patterns of methylation seem to be transmissible, and therefore function as alleles, from a genetic point of view. Histone modifications are not transmissible.”

In the paper

“The term ‘pangene’ is the origin of Wilhelm Johannsen's ‘gene’, proposed in 1909 in the important book where he also introduced the words ‘genotype’ and ‘phenotype’ [6].”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites [6] [6] Johannsen, W. Elemente der Exakten Erblickeitslehre, Gustav Fischer, Jena, 1909

In the paper

“Benzer proposed to adopt it as the basis for the definition of the new concept of the gene that he proposed, in replacement of the obsolescent ‘classical concept’, the ‘cistron’ concept. A cistron is a unit of genetic function, identified by applying a cis-trans test.”

What the sources say

• ?Not checked — no full text of the sourcecites [14] [14] Greenspan, R.J. Seymour Benzer (1921-2007), Curr. Biol., Volume 18 (2008), p. R106-R110 source

In the paper

“In the 1920s, the chromosomal theory had become an essential part of genetics and it gave a more material flavor to genetics. In the new theoretical framework, the genes had spatial significance: they were located on chromosomes, and they occupied a precise location each relative to the others: their ‘genetic distance’ could be calculated on the basis of the proportion of crossing overs.”

In the paper

“The original idea, proposed triumphantly around 1960, was that a gene is no more nor less than a DNA sequence that codes for the amino-acid sequence of a protein (or, more generally, a polypeptide).”

In the paper

“In the following years, still working on the mold Neurospora crassa, they showed that a single gene controls each step in a metabolic pathway. This led to the famous ‘one gene–one enzyme hypothesis’ [10].”

What the sources say

• ?Not checked — no full text of the sourcecites [10] [10] Horowitz, N.K. The one gene-one enzyme hypothesis, Genetics, Volume 33 (1948), pp. 612-613 source

In the paper

“In the new molecular context, the typical mutation unit is the nucleotide; the recombination unit consists of two adjacent nucleotides; and the functional unit is the sequence of nucleotides able to perform a physiological function”

In the paper

“Today, many molecular processes are known that challenge the traditional ‘one gene-one protein’ dogma. In reality, it seems hopeless to provide a general definition of the gene on the basis of exclusively molecular criteria”

In the paper

“Mendel's memoir remained largely unknown until 1900, when his ‘laws’ (plural instead of singular) were rediscovered.”

In the paper

“After the pioneering work of Herman Muller in the 1920s on the effect of X-rays on Drosophila, a genetic mutation was defined as a local alteration of a chromosome: a particular allele was transformed into another one, the ‘mutant gene’.”

In the paper

“These findings suggest that the information contained in our genome goes far beyond the usual picture of 20,000–25,000 protein-coding genes. There are many more functional units than those protein-coding genes.”

In the paper

“Benzer showed that recombination (crossing over) can occur in many places within a single gene, and this allowed him to discover the fine molecular structure of the gene. Simultaneously, Benzer showed that mutation events could also affect a given gene at many sites. This was the origin of the notion of ‘punctual mutation’”

What the sources say

• ?Not checked — no full text of the sourcecites [14] [14] Greenspan, R.J. Seymour Benzer (1921-2007), Curr. Biol., Volume 18 (2008), p. R106-R110 source

In the paper

“One is Hugo de Vries’ use of the words ‘pangenesis’ and ‘pangene’ in a book published in 1889 as Intracellular Pangenesis [4,5]. In this book, De Vries supported the existence of hereditary particles in all the cells of an organism. For these particles, he coined the word ‘pangene’”

What the sources say

• Not checked yetcites [4] [4] De Vries, H. Intracellulare pangenesis, Gustav Fischer, Jena Gustav Fischer, 1910 (English translation: Intracellular Pangenesis. Open Court, Chicago, Trad. partielle en français dans [5])
• Not checked yetcites [5] [5] Lenay, C. La découverte des lois de l’hérédité: une anthologie (1862-1900), Presses Pocket, Paris, 1990

In the paper

“Bateson's 1902 book was certainly a key event, because it showed that Mendel's first law (the law of segregation, applying to just one character) applied not only to plants but also to animals; Bateson also defended that the Mendelian laws of hybridization did not apply only to the results of crosses between individuals of distinct varieties or species, but to a huge number of individual”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites [2] [2] Bateson, W. A Defence of Mendel's Principles of Heredity, Cambridge University Press, Cambridge, UK, 1902

In the paper

“In the mid-1930s, genetics was conventionally subdivided into three major sub-disciplines: formal genetics proper; population genetics, which provided the main theoretical basis for the Modern Synthesis; and physiological genetics, the aim of which is to study how the genes produce their effects”

In the paper

“Recent data show that 98.5% of our genome is not translated into proteins, but more than 70% is transcribed into RNA. Furthermore, 70,000 promoter regions (the sites where proteins bind to control gene expression) and 400,000 enhancers (regulatory sites that affect the expression of distant genes) have been discovered in the human genome [17].”

What the sources say

• ?Not checked — no full text of the sourcecites [17] [17] Maher, B. The human encyclopaedia, Nature, Volume 489 (2012), pp. 46-48 source

In the paper

“However, the word ‘genetics’ was only coined in 1906, to designate the new science of heredity.”

In the paper

“Conversely, Thomas Hunt Morgan (1866–1945), who was the main architect of the fusion between Mendelian genetics and the chromosomal theory, did not accept the former in the early 1900s. In 1908, however, he began working on heredity with Drosophila melanogaster (fruit fly), using both the chromosomal theory of heredity and Mendelian genetics.”

In the paper

“For instance, William Bateson, in a sense the founding father of genetics, never accepted this theory.”

In the paper

“Split genes, commonly found in eukaryotes and viruses, are genes composed of a succession of exons (some of which corresponding in part or in totality to coding sequences) and introns (or intervening sequences eliminated after splicing of the exons at the RNA level).”