Research Paper Published on Top Journal

　　 　　

On June 21st, the international academic journal  Science  published online paper "Genetic Basis of Ruminant Horn Development and Rapid Regeneration of Pilose Antler", which was jointly published by Professor Jiang Yu's research team from College of Animal Science and Technology of Northwest A&F University and 9 domestic and foreign units including Northwestern Polytechnical University. From the perspective of genetics, it is proposed for the first time that ruminant horns have the same cell origin-head neural spine stem cells, and their development process uses basically the same gene regulation pathway, which provides evidence for ruminant horns to have a single evolutionary origin and occurrence and development mechanism.

Why do cattle, sheep and deer have horns? What are the similarities and differences in genetic development between cattle and sheep horns and deer horns? In fact, they all belong to the order of ruminants, and they are the only existing mammals with bony appendages on their heads, which are known as horns. Different groups of animals with subhorned orders have their own unique horns. For example, the horns of giraffes are composed of bony processes covered only by skin and hair; The horn of bovine family also has a bony core, but it is covered by a horny sheath, which grows for life and cannot regenerate without bifurcation; The horns of deer animals fall off periodically and regenerate once a year. They are called velvet antler in the growth stage, and their germinal tissue is above velvet antler, so they will branch and grow. After the growth stops, the antler will calcify into antlers, and there is no horn sheath. Some animals with horns don't have horns, such as musk deer and roe deer.

Most herbivores have no fangs and claws. Horns are not only their self-defense tools against predators, but also the main tools for competing for mates and territories among the same kind. However, the existence of horns is not conducive to animal husbandry production management, and has great potential safety hazards. Therefore, breeders put a lot of energy into breeding hornless cattle and sheep breeds. Recombinetics of the United States used gene editing technology to cultivate black-and-white cows that don't grow horns, so that calves don't have to go through the painful process of being branded after birth. However, the hornless mutation used in goat and sheep gene editing breeding has not been confirmed yet. So are the development and growth of cattle horns, sheep horns and antlers controlled by the same genetic pathway? Does bone angle come from one origin or multiple origins? It has always been an unresolved scientific problem.

By comparing the genomes of different ruminants and up to 270 transcriptome, it was found that the horn and velvet antler have similar gene expression patterns, and the specifically highly expressed genes mainly come from the genes expressed in bone, skin, brain and testis. The study was carried out by Northwest A&F University, in conjunction with Northwestern Polytechnical University, Chinese Academy of Agricultural Sciences, Copenhagen University of Denmark, Kunming Institute of Zoology of Chinese Academy of Sciences, Sichuan Institute of Musk Deer Breeding, Shihezi University, Xinjiang Academy of Animal Husbandry, Shenzhen Huada Gene Research Institute and American Recombinetics. These horn tissue-specific highly expressed genes. Along with some rapidly evolving genes, they are involved in the migration pathway of nerve ridge cells. Therefore, it is proposed for the first time from the genetic point of view that the horns of ruminants have the same cell origin-head neural spine stem cells. It gives genetic evidence for the single evolutionary origin of ruminant horns, provides theoretical basis for the breeding of hornless cattle and sheep, and key target genes for the production of hornless cattle and sheep by gene editing.

In addition, antlers have an extremely fast regeneration rate. From spring to summer every year, their cell division and proliferation rate even exceeds the growth rate of cancer tissues (for example, red deer horns grow about 1.7 cm every day). However, long-term statistics from Philadelphia and San Diego zoos show that deer species have a lower incidence of cancer. This study found that many proto-oncogene pathways were activated and genetically changed in antler tissue, which may play an important role in regulating the rapid regeneration of antler. At the same time, several important tumor suppressor genes also underwent deer-specific genetic changes, which may strengthen the anti-cancer effect. Therefore, further functional research will have important scientific significance in proving the potential mechanism of rapid but controlled cell growth and exploring deer as an organ regeneration model and cancer model, and provide new ideas and methods for cancer treatment and prevention.

This research is especially grateful to the support of the high performance computing platform of Northwest A&F University. Funding comes from the National Natural Science Foundation of China Outstanding Youth Fund (31822052), general projects (31572381) and National Youth Thousand; Northwestern Polytechnical University Talent Team Construction Fund, National Youth Top-notch Project; Pilot Project of Chinese Academy of Sciences (XDB13000000, XDA16010405), National Talent Project of Shaanxi Province; Danish Youth PI Fund (VKR023447); National Natural Science Foundation of China (31501984), Jilin Natural Science Foundation of China (20170101158JC) and Basic Research Fund of Central Institute of Public Science (Y2019GH13).

Original link: https://science.sciencemag.org/content/364/6446/eaav6335? Intcmp="trendmd-sci