Dr Tony Papenfuss from the Walter and Eliza Hall Institute’s Bioinformatics division and Professor Marilyn Renfree from The University of Melbourne’s zoology department led the study which has also revealed the genes behind the kangaroo family’s unusual reproductive system and the gene that may be responsible for the kangaroo’s characteristic hop.
The results have been published today in the journal Genome Biology.
The sequence of the first kangaroo genome is significant to the study of mammalian evolution. As kangaroos are separated from humans by a large evolutionary time span, it is hoped that the tammar wallaby DNA sequence may reveal crucial information about the early mammalian species from which humans evolved.
Dr Papenfuss said the discovery of new genes involved in immunity, development, lactation and reproduction highlighted the valuable insight that sequencing the genetic material of marsupials could deliver.
“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,” Dr Papenfuss said.
“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.
As well as producing the genome sequence, Dr Papenfuss and colleagues Professor Terry Speed, Dr Matt Wakefield and Dr Zhi-Ping Feng also generated a complementary ‘transcriptome’ sequence.
Dr Wakefield said the transcriptome represented a catalogue of how strongly each gene is switched on or off at different stages of the tammar life cycle and in different parts of the kangaroo’s body. “Study of the transcriptome will allow many more interesting questions to be asked about how kangaroo genes compare to their counterparts in humans,” 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,” Professor Renfree 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,” Professor Renfree said.
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.
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