AUSTRALIA: Hopping into history

The Australian tammar wallaby is the first member of the kangaroo family to have its genetic makeup sequenced. An international research collaboration, led by Australian scientists, has provided many insights into the genetic makeup of the iconic 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.

Joint lead authors of a paper on the study, published in the international journal Genome Biology, 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," Renfree said. "The genetic sequence of the tammar wallaby has provided new insights into marsupial early development, lactation and the immune system."

Renfree said kangaroos and wallabies, like all marsupials, had 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.

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

Papenfuss said the discovery of new genes involved in immunity, development and reproduction highlighted the valuable insight that sequencing the genetic material of Australian native fauna and flora could deliver.

"The new information that the genome sequence provides will also help to contribute to our understanding of Australian wildlife health and conservation," he said. "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 Kim Worley from the Human Genome Sequencing Center at the US Baylor College of Medicine, who led the American component of the sequencing, said the tammar wallaby had joined other sequenced mammalian genomes that were wonderful resources for understanding mammalian biology.

The study was supported by several groups including the US National Institutes of Health, the Australian Genome Research Facility, and the Australian Research Council's Centre of Excellence in Kangaroo Genomics, with partners at the universities of Melbourne and New South Wales, the Australian National University, the Walter and Eliza Hall Institute of Medical Research and the Australian Genome Research Facility.