Researchers from the Chinese Academy of Sciences have reported successfully recombining chromosomes completely and successfully in a living mouse, an animal named Xiao Zhu, or “little bamboo.”
In the laboratory of the Chinese Academy of Sciences, an unpretentious rat called Little Bamboo is in fact the first of its kind, an artificial species. In this mouse’s genome he has 19 pairs of chromosomes, one less than in nature, but this is all due to the intervention of human scientists.
The Beijing team “completely recombined” the mice’s genes, breaking the chromosomes into different segments and then putting them back together in a new setup. This is the first time such a process has been carried out on an organismal scale without severely affecting viability. This effectively means that Little Bamboo is the first of a completely new artificial species of rat, and the world’s first mammal with completely engineered genes.
“Mammalian genomes are much more complex than yeast genomes, and full mammalian chromosomal rearrangements remain unsuccessful.” science and technology daily.
Chromosomes are condensed strands of DNA bundled into various shapes that help keep the DNA organized in the nucleus of the cell. They are roughly equivalent to compressed digital documents and help reduce the amount of space your data takes up on your cell’s hard drive.
These DNA bundles are naturally formed during sexual reproduction when each parental chromosomal segment joins with the other parent’s equivalent chromosomal segment to form an entirely new genome that inherits both segments. decompose and recombine into This process is very complex and delicate, and errors here can cause a great many problems for the affected offspring. Attempts have been made to interfere with this process, but with very limited success, using only single-celled organisms such as yeast.
However, current research shows that such interventions can also be performed in living organisms, paving the way for synthetic biology to tackle a whole range of new experiments.
For this paper, Lee and his colleagues used the gene editing tool CRISPR. It’s based on a natural genetic modification process and works like scissors and glue so the researcher cuts his DNA strands in specific areas, welds in new bits, and then ties them back together. can do. They used his CRISPR to manipulate the chromosomes contained in unique germline stem cells, mice they created specifically for this experiment.
Previous attempts by the team resulted in the aforementioned recombination error. The problem arose when trying to piece together two very long chromosome fragments. They bond imperfectly. These cells continue to grow into unhealthy, deformed specimens, or specimens that exhibit bizarre behavior, or cause the animal to become completely unviable and die.
Their answer was to use shorter chromosomal sequences and reduce the total number of chromosomes to 19 pairs. This is one less pair he has than a mouse naturally has. This approach led them to create a new species that appeared to be perfectly healthy and exhibit normal behavior despite having a completely different chromosomal package in their cells compared to natural mice. Succeeded.
The recombinant mice were then bred with unmodified animals and successfully conceived, albeit at a relatively low rate. The offspring of these pairs contain the parent’s manipulated chromosomes, indicating that the effects of such gene editing can spread across generations.
“This represents the world’s first complete chromosomal rearrangement in mammals and a new breakthrough in synthetic biology,” said Li. south china morning post“This work represents a breakthrough in bioengineering technology to understand the effects of large-scale remodeling of mammalian chromosomes, and to better understand the molecular mechanisms behind growth and development, reproductive evolution, and even the creation of species.” It helps me understand it better.”
Because of their observed ability to conserve genes across generations, the team hopes their approach will help explain how genetics affect conditions such as infertility and cancer, and how they can be treated. We are confident that it will be useful for researchers studying
The experiment had been approved by the Research Ethics Committee of the Chinese Academy of Sciences, but now the use of CRISPR on human embryos is strictly prohibited in China, so the team has taken many steps in this direction. rice field.