Evolution and function of molecular scissors: topoisomerases and meiosis
During meiosis, numerous exchanges between maternal and paternal chromosomes occur. These recombination events proceed by a mechanism of DNA breakage and repair during the prophase of the first division of meiosis.
These breaks are produced by enzymes related to topoisomerases.
In two studies published in Molecular Biology and Evolution and Nature communications, scientists have contributed to understand how this activity has specialized during evolution to become involved in sexual reproduction by analyzing the evolutionary origin of these proteins.
Born in Algiers in July 1939, Jacques Demaille was one of the fathers of the French genome program. As a physician and researcher, he left his mark on medical research in Montpellier. After a stay in the United States in the laboratory of Edmond H. Fischer's laboratory in the United States, where he won the Nobel Prize in Physiology in 1992, he directed the Centre de Recherche en Biochimie Macromoléculaire (CRBM) from 1983 to 1997 and founded the Institut de Génétique Humaine (IGH) in 1998, which he directed until 2002. He was also president of the University of Montpellier and director of the CNRS Life Sciences Institute. He will be remembered as a passionate, inspiring and outstanding builder.
Early embryos show signs of genomic instability as well as the presence of mutations whose origin was unknown until now.
In this article, published in the journal Nucleic Acids Research, scientists were able to identify a molecular mechanism responsible, and showed that it is the DNA damage tolerance system, which could also contribute to variations in genetic background between individuals.
A video illustrating the organization of the genome in 3D has been released by the Cavalli team. The video summarizes the current understanding of genome organization in the three-dimensional space of the cell nucleus. It illustrates the different layers of chromosome organization, from nucleosomes, which envelop 146 base pairs of DNA, to chromosome territories, which can contain hundreds of millions of base pairs of DNA sequence. Between these two extremes, the hierarchical folding of the chromatin fiber into "nucleosome clusters", "chromatin nanodomains or CNDs", "Topologically Associating Domains or TADs" (including their formation mechanism via loop-extrusion) and "Compartments A and B" are presented.
In the description of the video, references can be found that complete the content.