动物实验 z-bio 2021-10-21 271

　　Scientists at Harvard University modified the zebrafish to start forming limb-like appendages by regulating individual genes. Researchers discovered this mutation by accident and screened various genetic mutations and their effects on fish development. This may provide clues for understanding the transition of vertebrates from sea to land. M. Brent Hawkins, the first author of the study, said: "I can't believe that a single mutation will produce a completely new bone or joint. I found that this is because none of the 30,000 bony fish have this mutation.

　　The mutation really surprised us. "Hawkins recently received a PhD in biology and evolution. Harvard University biology. Hawkins and colleagues discovered a mutation that caused the "proximal radius" of the zebrafish pectoral fin bone, which is attached to the fish's shoulder The joints are like a human arm attached to a shoulder. However, unlike humans and other quadrupeds, zebrafish do not have bones like arms and fingers. However, this mutation allows the formation of a new set of long bones, called With a "medium radius", the long bone can be connected to the existing proximal radial joint to form a joint similar to an elbow joint.

　　Associate Professor of Genetics at Harvard Medical School and Matthew Harris, an orthopedist at Boston Children's Hospital, are the lead authors of this study. He said: "Through this mutation, the fish gains new bones, joints and muscle attachments. Yes. No genetic mutations of muscles, joints or bones are required. The system has been adjusted. You can also adjust any changes you make. Everything."

　　Genetic analysis revealed two genes. Both vav2 and waslb mutations can independently cause this developmental change. It was previously thought that these two genes had nothing to do with skeletal development, but in the analysis of this study, both genes activated the Hox (homotype) mechanism that controls the center of the limbs, which was proved to be related to skeletal development (1) . "Through these zebrafish, we can actually prove that these mutations activate developmental mechanisms that are usually thought to occur only in the limbs. Therefore, they have never been found in bony fish. These patterns are thought to be related only to the limbs, not only because Their form is also because of their ancestral pattern."

　　The limbs are vertebrates, and birds and bats can fly. Considered to be an important evolutionary innovation, it enables zebrafish to walk on land. These results indicate that this group of fish was previously thought to have lost or silenced the mechanisms necessary for limb evolution, but actually retained the unique ability to form these structures. Hawkins said: "Through investigation, we found unexpected commonalities between fins and limbs. I think we will find more similarities."

　　Despite these findings, the new bones changed the pectoral fins of zebrafish. Getting my function is still a problem. In the next step, the researchers will use precision video microscopes to determine whether these new bone joints are sufficient to affect the movement of zebrafish. Hawkins said: "Usually these structures do not have the joints needed to move on land, but it is interesting to see if this change can be placed and adjusted on the platform."

　　These mutations were caused by discoveries. Researchers have taken the first step in how vertebrates can land on the ground, and the genetic and developmental mechanisms required to realize them. Hawkins said: "That's not all, but you can see the windows. Let us solve this mystery. How fins evolved into modern limbs." "For me, these mutations taught the development and formation of animals. It gave me a complex structure. This often reminds me that not all "monsters" are scared. If you look closely, they can tell you A lot of information about yourself.