Strewth: first wallaby genome published

It’s not every day a nation publishes the genome sequence of an animal from its coat of arms (a much more difficult task for British scientists). But today sees the release of the first complete genome of a tammar wallaby (Macropus eugenii).

The genome sheds light on some of its unique traits, such as its unusually 12 month gestation, its seasonal breeding and sophisticated lactation. It also hints at genes that are responsible for the wallaby and kangaroo’s signature hop.

Other discoveries from the genome include the 1,500 smell detector genes responsible for the tammar wallaby's excellent sense of smell, and genes that make antibiotics in the mother's milk in order to protect kangaroo newborns from E. coli and other harmful bacteria.

Along with the genome sequence was published the transcriptome, giving an indication of how genes are switched on and off through the lifetime of the animal. Study of the transcriptome will allow many more interesting questions to be asked about how kangaroo genes compare to their counterparts in humans.

"The tammar wallaby sequencing project has provided us with many possibilities for understanding how marsupials are so different to us," said Professor Marilyn Renfree from The University of Melbourne’s zoology department, one of the study’s lead authors.

“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,” said Dr Tony Papenfuss from the Walter and Eliza Hall Institute’s Bioinformatics division, and another lead author.

“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,” he said.

Professor Renfree said the tammar wallaby genome sequence showed tammars share 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,” she said.

She said 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.

“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," said Renfree.

The genome was sequenced to 2x coverage using Sanger sequencing complemented by next generation sequencing and integration of extensive physical and linkage maps to build the entire genome assembly.

The tammar wallaby is only the third marsupial and only the second Australian marsupial (after the Tasmanian devil), to have its genome sequenced.

The study was supported by the US National Institutes of Health, Australian Genome Research Facility, The Jack Brockhoff Foundation, Applied Biosystems, Australian Research Council Centre of Excellence in Kangaroo Genomics, the National Science Foundation, the University of Connecticut and the Victorian Government.

The genome sequence was published in the open access journal Genome Biology.