First Man-Made Living Mammals Created by Recombining Chromosomes of Living Mouse

Researchers at the Chinese Academy of Sciences report fully and successfully recombining the chromosomes of a living mouse, an animal named Xiao Zhu, or "Little Bamboo."

In a Chinese Academy of Sciences laboratory, Little Bamboo, also described by ZME Science as "one unassuming mouse," is, in fact, the first of its species, specifically a man-made species.

This genome of the mouse has 19 pairs of chromosomes, one lesser than natural, and it is all because of human scientists' meddling.

The Beijing team fully recombined the mouse's genes through a process whereby its chromosomes were broken into different segments and then put back together in a brand-new set-up.

This is the first time such a process was performed on the scale of a living organism minus seriously affecting its ability to live.

This means that Xiao Zhu is, as a result, the first of its kind of a new and man-made rat species, not to mention the first mammal in the world with fully recombined genes.

New Rat Species

According to Li Wei, the study's lead author, a researcher from the Institute of Zoology at the Chinese Academy of Sciences in Beijing, for the state-owned Science and Technology Daily, mammalian genomes are much more complex compared to yeast genomes, and complete chromosomal rearrangements in mammals have stayed unsuccessful.

Essentially, chromosomes are condensed strands of DNA bunched together in different shapes, helping keep DNA tidy in the nucleus of a cell.

They are roughly equivalent to a compressed digital document, "if you will, helping the data occupy less space" on the cells' hard drive, explained Wei.

These bunches of DNA are naturally breaking down and recombining during sexual reproduction when pieces of chromosomes of each parent bind to the equivalent chromosome pieces of the other parent to form a new genome that inherits parts of both parents.

Such a process is complicated and delicate, and errors here can cause many problems for any affected offspring.

CRISPR Gene-Editing Mechanism

Scientists have been attempting to interfere with this process to help deal with such errors when they occur, although they said they had had very limited success, and what success they indeed have, was only using single-cell organisms like yeast.

Nonetheless, the present research shows that such interventions can be carried out, even in living organisms, paving the way for synthetic biology to tackle an entire range of new experiments.

For this paper, as indicated in a News CBC report, Li, together with his colleagues, utilized the gene-editing mechanism CRISPR.

The tool is based on natural gene-modification processes and acts similar to the scissor-and-clue mechanism, enabling researchers to cut the strands of DNA in certain areas and weld in new bits before trying to string them back together.

The team used CRISPR to manipulate the chromosomes of a unique reproductive stem containing the mouse, which they developed specifically for this study.

New Species Created

Through this method, the researchers managed to create a new species that, despite having a different chromosome package in the cells compared to natural rodents, appears healthy and exhibits normal behavior.

The recombined mice were then allowed to mate with un-modified species, which did lead to successful pregnancies, albeit at a comparatively low rate.

Such pairs' offspring had the manipulated chromosomes of their parents, showing that the effects of such gene editing extend through generations.

Meaning, that for the first time worldwide, science experts have achieved full chromosomal rearrangement in mammals, making a breakthrough in synthetic biology, a South China Morning Post report specified.

Related information about roaring or screaming mice is shown on Ivan E.'s YouTub video below:

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