Researchers from the Institute of Zoology of the Chinese Academy of Sciences have announced the first controlled merger of chromosomes in mammals, and the study will help to understand how chromosomes transformation affects evolution.
For small periods of time, chromosomal selection remains stable in one species, but it is constantly changing on a scale of evolution, explained by scientists. For example, for a million years, rodents experience 3.2 to 3.5 adjustments in chromosomal sets and for primates 1.6 this small figure determines, for example, the difference between gorillas and humans.
In their work, scientists used stem cells from unfertilized mice embryos. The complexity of genetic modification is that some genes are activated only if they come from one of their parents. . This process is called genomic implanting. However, unfertilized embryos contain only the mother's DNA, so not all changes will be active in modified animals.
To circumvent this limitation, scientists blocked three areas responsible for genomic implantation, and then they modified the DNA of several embryos: the first group combined two medium-sized chromosomes in different configurations.
The study showed that the merger of the second chromosome with the top of the first led to premature progeny, while the opposite formed larger, more alarming and slower individuals, with only mice with four and five chromosomes able to produce offspring with wild rodents but at a much lower rate than standard laboratory mice.
The authors note that the results of the study show how chromosomes merges limit cross-breeding with others, leading to reproductive isolation and species formation over time.