A team of Chinese scientists has genetically engineered a kind of mouse with 19 chromosomal pairs, one pair less than is standard in this species, and part of these genetic changes can be passed to offspring, according to a new study published on Friday in the top journal Science. 

It's the first time that chromosome level engineering has been achieved in a mammal, through a new technique using stem cells and gene editing.

Through the study, the team hopes to reveal more about how the rearrangement of chromosomes can influence the way that animals evolve over time.

Chromosomes are packages of organized genes, provided in equal number from each parent. In nature, changing the number of chromosomes of an animal usually takes millions of years through the course of evolution.

Rodents have 3.2 to 3.5 chromosomal rearrangements per million years, whereas primates have 1.6. But those 1.6 changes result in the difference between humans and gorillas, since gorillas have two separate chromosomes whereas in humans they are fused, said the paper's co-first author Li Zhikun, researcher from the Institute of Zoology under the Chinese Academy of Sciences (CAS).

"We experimentally demonstrated that the chromosomal rearrangement event is the driving force behind species evolution and important for reproductive isolation, providing a potential route for large-scale engineering of DNA in mammals," said Li. 

In individuals, chromosome fusions or relocations can lead to health problems like childhood leukemia, according to Li.

The ability to engineer such changes in lab conditions could one day help correct misaligned or malformed chromosomes in human bloodlines, according to the study.

The research was conducted in strict accordance with relative Chinese laws and regulations, and has undergone ethics reviews, the CAS said.

(With input from Xinhua)