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A team of Australian and international scientists 鈥 including UNSW Sydney聽Professor Marc Wilkins 鈥 have made a significant breakthrough, successfully sequencing the full koala genome.聽

The consortium of scientists comprised 54 scientists from 29 different institutions across seven countries, led by聽, Director of the Australian Museum Research Institute, and , University of Sydney. The team sequenced over 3.4 billion base pairs and more than 26,000 genes in the koala genome 鈥 which makes it slightly larger than the human genome.聽The findings were published today in聽Nature Genetics.

Unlocking the genomic sequence gives scientists unprecedented insights into the unique biology of the koala: the highly accurate genomic data will provide them with new information that will inform conservation efforts, aid in the treatment of diseases, and help to ensure the koala鈥檚 long-term survival.

The 3.4 billion base pairs of the published koala genome were sequenced and assembled at the Ramaciotti Centre for Genomics at UNSW.

鈥淲e sequenced and then assembled the genome with supercomputers, allowing the consortium to study the >20,000 genes of this unique species,鈥 said , Director of the Ramaciotti Centre for Genomics at UNSW.聽

鈥淲e did so using new technology which can sequence very long pieces of DNA. This allowed us to do a very high-quality genome assembly 鈥 meaning that the result is the best marsupial genome to date, and one that鈥檚 on par with the human genome in terms of its quality, which is incredibly exciting.

鈥淏ecause of its high quality, this genome is now a fundamental resource for all the other marsupial genomes which have yet to be generated and studied. We will be able to use this as a reference for the entire marsupial community.鈥

Immune system

Professor Johnson added: 鈥淭he Koala Genome Consortium has been an ambitious journey, affording us great insights into the genetic building blocks that make up a koala 鈥 one of Australia鈥檚, as well as the world鈥檚, most charismatic and iconic mammals.聽

鈥淭his milestone has come from our vision to use genomics to conserve this species. The genetic blueprint has not only unearthed a wealth of data regarding the koala鈥檚 unusual and highly specialised diet of eucalyptus leaves, but also provides important insights into their immune system, population diversity and the evolution of koalas,鈥 she said.

According to Professor Belov, another important discovery was the characterisation of the composition of koala milk.聽 Like all marsupials, koalas do most of their development in the pouch. They are born without an immune system after 34-36 days gestation and spend ~6 months developing in the pouch.聽

鈥淲e characterised the main components of the mother鈥檚 milk 鈥 which is crucial for koala joeys,鈥 Professor Belov said. 鈥淲e identified genes that allow the koala to fine-tune milk protein composition across the stages of lactation, to meet the changing needs of their young.鈥

鈥淭hanks to the high-quality genome, the team was able to analyse and discover koala-specific milk proteins that are critical for various stages of development. It also appears these proteins may have an antimicrobial role, showing activity against a range of bacterial and fungal species, including Chlamydia pecorum, the strain known to cause ocular and reproductive disease in koalas,鈥 Professor Belov said.

Vaccine

Chlamydia causes infertility and blindness and has severely impacted koala populations in New South Wales and Queensland.聽Using information gained from the koala genome, scientists hope to develop a vaccine to fight diseases like chlamydia.

One of the most threatening processes to koala survival is loss of habitat through land clearing and urbanisation, which results in a reduction of habitat connectivity, reduced genetic diversity and puts koalas at high risk of inbreeding. The results of inbreeding can be highly detrimental to the survival of those koala populations, as it leads to reduced genetic diversity.聽

鈥淔or the first time, using over 1000 genome linked markers, we are able to show that NSW and QLD populations show significant levels of genetic diversity and long-term connectivity across regions,鈥 Professor Johnson said.聽

鈥淓nsuring this genetic diversity is conserved in concert with other conservation measures to protect habitat, reduce vehicle strikes, dog attacks and disease is the keys to the long-term survival of the koala.鈥澛

All of the sequence data generated by The Koala Genome Consortium has been deposited into public databases and made freely available to scientists around the world. 鈥淣ot only does open data promote the best interests of science, it also maximises the benefits that the koala populations, and the public, receive from such research,鈥 Professor Johnson said.聽

The koala is a native tree-dwelling Australian marsupial that is one of the world鈥檚 most fascinating and iconic mammals. Not only is the koala synonymous with Australia, it is also a powerful international symbol for the preservation and conservation of our natural world.聽

Wild koalas are currently found in eucalypt forest and woodlands across Eastern Australia (Victoria, New South Wales and Queensland) and have been translocated to other sites, such as south eastern South Australia and onto some islands such as Kangaroo Island, South Australia and French Island, Victoria.

Their unique and highly specific diet of eucalyptus (gum) tree leaves has resulted in koalas being especially vulnerable to habitat loss due to the clearing of native vegetation for agriculture and urban development.聽 The Australian Federal government lists koala populations in Queensland, New South Wales and Australian Capital Territory as 鈥榲ulnerable鈥 under national environment law.聽

鈥淥ur next efforts must be in the application of these findings to genetically manage koala populations and advance the treatment of the diseases affecting koalas, with the goal of conserving this very important species,鈥 Professor Johnson said.