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Successful genetic engineering in opossums

Recently, scientists at RIKEN’s Centre for Life Systems Dynamics Research successfully created the first genetically engineered opossums.

Genetically engineered animals, particularly mice and rats, have been extremely important for the study of biological processes as they carry virtually all the same genes that operate in humans. This has led to researchers now being capable of targeting and switching off genes to help assess their biological function. This is an essential part of the study of diseases, treatments and many other aspects in the clinical world.

Marsupials have several unique characteristics not shared by many other mammals. For example, they develop without functional placentas and pups are given birth to prematurely. Additionally, they have high susceptibility to skin cancer from UV light exposure and can also heal spinal injuries naturally. Therefore, marsupials provide beneficial insight to future mammalian genomic studies.

Opossum genome modification

In this study, scientists used opossums to explore gene modification in marsupials. This is because they are the genetic ancestors of marsupials and share many of their characteristics. As opossums show many biological similarities to mice and rats, scientists could use existing research models to administer hormones to manipulate key reproductive processes. This was achieved through the collection of opossum zygotes and subsequent genome editing via injection of CRISPR/Cas9. A surrogate mother was used for assisted reproduction of the genetically modified offspring. The genome editing targeted the Tyr gene, which provides instructions to produce tyrosinase. This is an enzyme located in melanocytes, which are specialised pigment cells. When the Tyr gene was disrupted, the absence of tyrosinase resulted in a failure to produce pigments and hence, the loss of skin colour was observed.

Therefore, the birth of albino offspring confirmed a successful transfer of the edited gene to the new opossum generation. Then, embryo transplantation into a surrogate mother took place to produce genetically modified offspring. This is the first time that this Crispr/CAS9 technology has been successful in opossums, presenting exciting new opportunities for further research into many more of the overlooked animal’s genes and their unique functions.

The future of mammalian embryo genetic engineering

This study has created a critical foundation for the expansion of mammalian reverse genetics. The successful methodologies highlighted in this research will undoubtedly be useful towards future in-vivo gene function studies. Opossums and marsupials trail closely behind eutherian mammals; hence this data could soon be applied to further subclasses, with this groundwork now laid out. We will surely see mammalian embryos included in future gene studies, given the huge potential in clinical applications, such as drug design and clinical diagnoses.

Image credit: Mario Hernandez from Pixabay