The first genetically engineered marsupial has been created by researchers at the RIKEN Center for Biosystems Dynamics Research (BDR). This study, which was published in the scientific journal Current Biology, will help to decipher the genetic basis of unique characteristics found only in marsupials.
Animals that have been genetically modified, particularly mice and rats, are extremely useful for studying biological processes. For example, researchers frequently silence genes to learn more about their normal functions. Because marsupials have distinct characteristics, studying them necessitates the creation of a representative animal model. The opossum, which is thought to be the ancestor of all marsupials, is currently the best option. The opossum, the first marsupial to have its entire genome sequenced, is a good model animal because its size and breeding habits are similar to those of mice and rats.
The opossum, like other marsupials, has a number of characteristics that are not shared by other mammals. It develops without a functional placenta, resulting in the premature birth of pups. It develops skin cancer, like humans, but not other non-marsupial mammals, simply by being exposed to ultraviolet light. In addition, unlike other mammals, newborn opossum pups with spinal cord injuries have the ability to heal themselves naturally. Because of these distinguishing characteristics, marsupial biology is gaining popularity. However, without established technology to genetically modify marsupials, it has been difficult to analyze their underlying genetics. Now, a research team led by Hiroshi Kiyonari at RIKEN BDR is using new gene-editing technology to kickstart opossum research.
Marsupials are one of three extant mammalian subclasses, each with its own set of characteristics not shared by other mammals. Future research can produce genetically modified marsupials that will have an impact on mammalian embryology, genomic imprinting, reproduction, neurobiology, immunogenetics, cancer biology, and even comparative evolution.
Hiroshi Kiyonari
Because the solution for genome editing is injected into the fertilized eggs, genome editing necessitates the systematic collection of fertilized eggs. Because opossums have a long estrus cycle and a strong sense of territoriality, it takes about a week for a couple to mate even if they live together, making the experiment difficult to carry out in a systematic manner. The researchers used a hormone used in mice and other laboratory animals to stimulate estrus in females, and they were able to significantly reduce the time required for mating.
To generate a genome-edited fertilized egg, the embryo must be implanted into a surrogate mother. The researchers successfully transferred a fertilized egg into the uterus of a fertile female opossum, as is done in mice and rats, and obtained pups. This is the first instance of embryo transfer technology being used in marsupials.
The solution required for genome editing is typically injected into the fertilized egg with a fine needle. The injection needle, however, cannot penetrate the opossum’s fertilized egg because it is surrounded by a thick layer of proteins and a hard shell-like structure. “Using a piezoelectronic element along with the needle, which allowed the needle to penetrate the hard shell coat and thick layer surrounding the egg, was one of the tricks to our success,” Kiyonari explains. As a result of the piezo, it is now possible to inject zygotes without causing significant damage.”
To validate the overall methodology, the researchers targeted a gene responsible for the production of body pigments. When this gene is faulty, pigment cannot be produced, and the skin is colorless. Some of the offspring born as a result of this experiment were albino, and their genes were passed down to the next generation. As a result, this is the first successful gene editing in marsupials.
Researchers can now focus on answering all of their questions about marsupial biology now that the process has been established. “Marsupials are one of three extant mammalian subclasses, each with its own set of characteristics not shared by other mammals. Following the validation of the technology in this proof-of-concept experiment, future research can produce genetically modified marsupials that will have an impact on mammalian embryology, genomic imprinting, reproduction, neurobiology, immunogenetics, cancer biology, and even comparative evolution “Kiyonari expresses himself.
