Science hope for threatened koalas

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PARIS, July 3, 2018 (BSS/AFP) – Australia’s koalas, their very existence
imperilled by disease, bushfires, car strikes, and dog attacks, face a more
hopeful future thanks to scientists cracking its genetic code, a study said
Tuesday.

A mammoth effort by more than 50 researchers in seven countries uncovered
26,558 koala genes, yielding vital DNA clues for vaccines against diseases
such as sexually transmitted chlamydia, which blinds the cuddly critters and
leaves them infertile.

“The genome has allowed us to understand the koala immune genes in detail
for the first time,” said Rebecca Johnson of the Australian Museum Research
Institute, a co-author of the study published in Nature Genetics.

“These genes (are) directly contributing to vaccines for koalas,” she told
AFP.

The DNA code should also boost koala breeding programmes.

It revealed that inbreeding was higher among koalas from Victoria and South
Australia states than among their cousins from Queensland and New South
Wales.

The discovery “allows us to make recommendations for how to preserve the
populations with high genetic diversity and how animals might be translocated
to improve the diversity of inbred populations,” Johnson said.

From between 15 and 20 species some 30 to 40 million years ago, a single
species of koala survives in Australia today — some 330,000 individuals in
all, most living in protected areas.

As few as 43,000 may be left in the wild, down from an estimated 10 million
koalas before Europeans began settling Down Under in around 1788.

Koala numbers were decimated partly by a thriving pelt trade from the 1870s
to the late 1920s.

The International Union for Conservation of Nature qualifies the koala’s
protection status as “vulnerable”.

– Picky eater –

Koalas are marsupials — mammals that raise their young in a tummy pouch.
Born without an immune system, the koala joeys are heavily dependent on their
mothers’ milk.

A key discovery resulting from the genome sequencing was the discovery of
koala-specific milk proteins that may also have “powerful antibiotic
properties… (that are) really effective against bacteria and fungi”.

“So we think one day we could develop antibiotics for humans and other
animals straight out of the koala’s pouch,” the study’s co-author Katherine
Belov of the University of Sydney told AFP.

“And the implications for that are huge, because of course antibiotics
resistance is on the rise and we are seeing more and more novel bacteria
emerge that are resistant to all drugs on the market.”

Koalas’ unusual diet consists mainly of eucalyptus leaves, which would be
toxic for most animals and are low in calories, meaning the fluffy “bears”
have to eat a lot and rest often.

The new study identified genes responsible for liver detoxification that
likely permitted koalas to become such dietary specialists, thus avoiding
competition for food with other animals.

Unfortunately, their pickiness now adds to the survival pressure, with
eucalyptus trees cleared for farmland or for urban construction.

Global warming, experts say, will further raise the risk of devastating
forest fires and tree death.

The koala genome is bigger than the human genome, with about 20,000 genes.

It is the most complete genome yet sequenced for any marsupial, of which
there are about 300 species, the researchers said.

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