Kangaroo genome hops into history

The genetic makeup of the Australian tammar wallaby has been sequenced. Photo: Marilyn Renfree

The international research collaboration, led by Australian scientists, has provided many insights into the genetic makeup of the iconic Australian kangaroo, including the genes behind its unusual reproductive system and how some genes control the development of the kangaroo’s specialised toes that allow them to hop.

The results have been published in the international journal Genome Biology.

The joint lead authors on the paper, Professor Marilyn Renfree from the University of Melbourne and Dr Tony Papenfuss from Melbourne’s Walter and Eliza Hall Institute, noted that as in other mammals, the tammar shares many thousands of genes with humans.

“What is interesting is the surprising similarities as well as the differences in the genes uncovered in this study,” Professor Renfree says.

“The genetic sequence of the tammar wallaby has provided new insights into marsupial early development, lactation and the immune system.”

Professor Renfree says kangaroos and wallabies, like all marsupials, have many unusual biological characteristics.

 “They give birth to tiny under-developed young after a very short pregnancy, which is then followed by a long and sophisticated lactation period while in the mother’s pouch,” she says.

“This includes the simultaneous provision of two types of milk from adjacent mammary glands to offspring of different ages. This is like the left breast and right breast making milk of two completely different compositions.”

Dr Tony Papenfuss says the discovery of new genes involved in immunity, development and reproduction highlights the valuable insight that sequencing the genetic material of our native fauna and flora can deliver.

“The new information that the genome sequence provides will also help to contribute to our understanding of Australian wildlife health and conservation,” Dr Papenfuss says.

“Using the genetic sequence we have discovered many new marsupial genes vital to the survival of the young, including genes that make antimicrobial proteins that kill bacteria in the dirty pouch.

“While many of the genes in the tammar sequence are shared with humans, the study revealed a new human gene that we didn’t even know humans had. This is the sort of exciting discovery that we hoped to uncover.”

Dr Sue Forrest from the Australian Genome Research Facility whose team led the Australian component of the sequencing says this exciting project shows how Australian facilities are able to unlock the valuable genetic information contained within our own unique Australian species.

“Importantly, dramatic technology advances now mean we can sequence Australian species faster and more cost effectively than ever before,” she says.

Dr Kim Worley from the Human Genome Sequencing Center at the Baylor College of Medicine USA, who led the US component of the sequencing, says that the tammar wallaby joins the other sequenced mammalian genomes that are wonderful resources for understanding mammalian biology.

Sequencing of the wallaby genome is a dream come true for Professor Jenny Graves, a long-time campaigner for sequencing genomes of Australian animals, and the foundation director of the ARC Centre of Excellence in Kangaroo Genomics.

“Our work mapping wallaby genes to chromosomes provides a basis for arranging and interpreting the sequence,” she says.

The study was supported by the State Government of Victoria, the National Institutes of Health, USA, Applied Biosystems (Life Technologies), the Australian Genome Research Facility, the Jack Brockhoff Foundation and the Australian Research Council’s Centre of Excellence in Kangaroo Genomics, with partners at the University of Melbourne, ANU, University of New South Wales, The Walter and Eliza Hall Institute of Medical Research and the Australian Genome Research Facility.