Scientists used supercomputers to finally crack the genetic code of koalas

Image: University of Sydney
  • Scientists have sequenced the koala genome for the first time.
  • The five year project was completed by a global consortium of 54 scientists from 29 organisations.
  • The massive data will help scientists in efforts to conserve koala populations.
  • The research also discovered an important characteristic of the composition of koala milk.

The full koala genome has been sequenced, in a multi year project using supercomputers, for the first time.

An international consortium, of 54 scientists in 29 organisations, led by Australian scientists and geneticists reported the koala genome sequence in a paper published in the journal Nature Genetics.

Considered to be the most complete marsupial genome sequenced to date in terms of quality, equal to that of the human genome, the data will provide scientists with information to help habitat conservation, tackle diseases and ensure the animal’s long-term survival.

Jennifer Graves, Distinguished Professor of Genetics at La Trobe University and winner of the 2017 Prime Minister’s Prize for Science, said: “We could never have imagined, when we were pioneering koala genetics in the 1980s, that one day we’d have the entire koala genome sequence.”

In a project started in 2013, the scientists sequenced more than one billion base pairs and more than 26,000 genes in the koala genome, which makes it slightly larger than the human genome.

Rebecca N. Johnson, Chief Scientist of the Australian Museum, and colleagues say the genome mapping enables a holistic, scientifically grounded approach to koala conservation.

“Koala numbers have plummeted in northern parts of its range since European settlement of the continent, but increased in southern sections of the range, notably in parts of Victoria and South Australia,” the researchers write.

“The uneven response of koala populations throughout its range is one of the most difficult issues in its management.”

Chlamydia, which causes infertility and blindness, has severely impacted koala populations in New South Wales and Queensland.

Current estimates put the number of koalas in Australia at 329,000 and a continuing decline is predicted.

The researchers discuss the findings:

Katherine Belov, co-lead author at the University of Sydney and Professor of Comparative Genomics, says an important discovery was the characterisation of the composition of koala milk.

They are born without an immune system after 34 to 36 days gestation and spend about six months developing in the pouch.

“We characterised the main components of the mothers’ milk – which is crucial for koala joeys – born the size of a jellybean and weighing half of one gram,” Professor Belov says.

“We identified genes that allow the koala to finetune milk protein composition across the stages of lactation, to meet the changing needs of their young.

“Thanks 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.”

The 3.4 billion base pairs of the published koala genome were sequenced at the Ramaciotti Centre for Genomics, at the University of New South Wales, using new sequencing technology.

UNSW Professor Marc Wilkins, director of the Ramaciotti Centre for Genomics, said: “We then assembled the genome with supercomputers, allowing the Consortium to then study the 20,000+ genes of this unique species.”

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.

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