(ORDO NEWS) — German scientists from the Institute for Plant Breeding of the Max Planck Society have identified a previously unknown mechanism that accelerates the evolution of DNA and genomes. The results of the study are described in a paper published in the journal Cell.
It is noted that the main role in this process is played by centromeres, which are the central region of chromosomes, the point at which sister chromatids join to form the X-shape.
Sister chromatids on the same chromosome are identical copies of each other that appear when DNA is replicated.
When a cell divides, each of the chromatids ends up in its own daughter cell. In most organisms, the chromosomes have one centromere, but some have several such structures, then the chromosomes are called holocentric – as opposed to monocentric chromosomes.
To determine how holocentricity affects the organism’s genome, the researchers used high-fidelity sequencing technology to sequence the genomes of three sedge plant species: Rhynchospora pubera, R. breviuscula, and R. tenuis. The results were then compared with the genome of their closest monocentric relative, Juncus effusus.
It turned out that there are strong differences in the organization of the genome and the behavior of chromosomes in holocentric and monocentric organisms. In the former, the functions performed by the centromere are distributed over numerous centromere domains.
Also, in holocentric species, the genes are evenly dispersed along the length of the chromosomes, and are not located at a distance from the centromeres and their surrounding areas.
The scientists concluded that holocentromeres stabilize chromosomal fragments and accelerate genome evolution, or an organism’s ability to make rapid, massive changes to its DNA structure. The authors of the work believe that their results can be applied in plant breeding.
Earlier, scientists from the University of Southern Denmark disproved the theory about the shorter life expectancy of men.
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