I have horns on my head! "Little Secrets" from Ruminants

Totograph: Cheng Weijia
At the Qinchuan cattle breeding base at Northwestern University of Agriculture, Forgion and Technology, a cow sits leisurely on the ground, his mouth like chewing gum. The sharp horns highlight its "sacred and inviolable" status in the sunlight.
These such ruminants, Jiang Yu, a professor at the School of Animal Science and Technology at Northwestern University of Agriculture, Foraging and Technology, and his co-workers,
Qiu Qiang,
" cattle, sheep and deer, are mostly herbivores without fangs and claws, and horns are both a self-defense tool for their hunters and a major tool for competing for mates and territories among their peers. Jiang Yu told China Science that studying these horns is one of their daily pleasures: How did they develop? Why are there so many shapes? ......
Among these horns, the gorgeous antlers stand out. Like the "black jade severity" skill, even breaks can continue to come up with new ones. What the hell is going on here?back to the beginning, the cow is not actually eating grass, by the keeper held in the heart of it has been full of food and drink. Why "pretend" to chew food? It turns out that these are all "ruminant" mechanism troublemakers.
" this kind of animals eat very quickly, a little bit of gnawing immediately swallowed, rushed to a safer place in the stomach. But they don't chew when they eat, so a lot of food doesn't digest. Their stomachs are special, divided into four chambers, in turn known as the tumor stomach, mesh stomach, valve stomach and wrinkled stomach. One of the main storage and digestion plant fibers is the tumor stomach, which, like vomiting reflexes, returns un chewed food to the mouth (ruminant) for digestion. Jiang Yu said.
in these ruminants, in addition to this unique tumor stomach, its various shapes of bone horns are considered to be the evolutionary history of animals organ shape innovation miracle. Wang Wen told China Science daily that ruminants are the only existing group of animals with bone horns, and ruminants in different sciences have different forms of horns.
Wang Wen introduced, "for example, the horn of the giraffe is composed of bone protrusions covered only by skin and hair; Its raw tissue is above the deer antlers, so it grows in forks. When growth stops, the antlers are calcified into antlers, and there are no horns. Some animals with adversity also do not have long horns, such as mus with mules and mules. "
deer, especially deer, whose horns grow at an extremely fast rate. Every spring to summer, newly grown antlers grow about 1 to 2 meters long, which means an average of 1.7 to 2 centimeters a day, and cell division and proliferation even faster than cancerous tissue.
and even more interesting is that the deer, which grows at a "cancer rate", has a lower cancer rate of its own, with a one-in-five chance of developing the disease in other species.
are all horns, why is it so different? Leaving aside this different face value, why does antlers still possess this special fairy skill? Even the bones of a species seem to be "stronger" than their peers? The scientist fell into meditation.this, the researchers used evolutionary and comparative genomics to compare big data to look for genomic differences and genes expressed in horned ruminants and other mammals.
first of all, we need to know that these horns are not the bones that connect the head itself, but the new organs produced by the tissue. During development, it is originally a separate, small cell cluster that migrates from nerve cells. After receiving fresh tissue from the species, the team began an analysis of the transcription group and conducted physiological, bio-bio-experiments such as dyeing on early embryos, Jiang said.
, the cells gradually developed independently into the core bones of the horns, which eventually be integrated into the skull. Jiang Yu made an image analogy to reporters: "It's like a baby is born with as many as 305 bones, but then some of the bones may fuse, for example, the skull will be fused from a dozen pieces into six pieces." This suggests that during the cell's division and proliferation process, it can lead to tissue fusion. "
, the question is, why do these tissues develop into horns of different shapes?" Even a cornerless situation? Looking at the plate's "freshly baked" horn tissue, the experimenters analyzed its genome expression.
By comparing different types of ruminant genomes with up to 270 transcription groups, the team found that horns and antlers had similar patterns of gene expression, with specifically high-expression genes collected primarily from genes expressed in bone, skin, brain and testicular tissue. These angular tissue-specific high-expression genes, along with some rapidly evolving genes, are involved in the neural ridge cell migration path, which means that the horns of ruminants may have the same cell "ancestor", the head ridge stem cells.
why some animals don't have horns, it's simple, because their genes are 'broken,'" he said. Jiang Yu said playfully.
, of course, the most interesting thing for scientists is the magical antlers, a species like the "eddy little strong" that has greatly attracted the interest of cancer researchers.
team found that multiple pathogenic gene paths, activated in antlers and genetically altered, may play an important role in regulating the rapid regeneration of deer antlers. At the same time, several important anti-cancer genes have also undergone genetic changes, which may strengthen the anti-cancer effect.
why can antlers grow rapidly and animals themselves are less susceptible to cancer? Originally only because of the "cancer mountain." Today, Qiu and his team will conduct in-depth research on demonstrating the potential mechanisms of rapid controlled cell growth and exploring deer as organ regeneration models and cancer models, "which will provide new ideas and approaches to cancer treatment and prevention." Qiu Qiang said.don't look at these horns are usually very powerful, in livestock production they are not welcome.
" horns are very large and sharp, used against natural enemies or to fight each other. He said that in the same kind may cause mutual harm, if the mood is not good to you, the consequences are even more unimaginable. "Jiang Yu spread out the stall, " so the use of hornless cattle and sheep for livestock production, for breeders, milkers and the safety of the animals themselves is very important, in addition to hornless ruminants can also be used for long-horned nutrients more in meat production and milk production. "
but there are great challenges in choosing such hornless varieties. One is that the species has not yet been selected to be complete. Although breeders put a lot of effort into breeding hornless cattle and sheep breeds, using gene-editing techniques to produce black-and-white flower cows that don't have long horns, the calf doesn't have to go through the painful process of being branded out of its horns after birth. But the hornless mutation used in gene-editing breeding for goats and sheep has not yet been confirmed.
, the selection of new varieties may not lead to an increase in livestock production. "If a cow with horns wants to be bred into a hornless breed, it needs to be hybridized with a hornless variety, but its milk production may decrease after hybridization, resulting in losses. An American gene-editing breeding company has obtained a high-yielding hornless black-and-white cow by using gene editing to target mutations in hornless genes. For this reason, Jiang said, the team is further exploring and editing the targeted mutations that affect the hornless genes of hornless sheep and hornless goats.
Wang said the findings are important for understanding the evolutionary history of ruminants, regenerative medicine, tumor biology, and the development of new breeds of livestock.
, after all, is there anything more important to this improved new breed than the "harmonious coexistence" of everyone without a fight?
paper information: DOI: 10.1126/science.aav6335