koala_genome team_2014_10_23
The koala genome team at work in the lab at the Australian Centre for Wildlife Genomics at the Australian Museum Research Institute. © Stuart Humphreys, Australian Museum.

Australian researchers have taken a big step towards unlocking the genetic secrets of one of the continent's most iconic animals: the koala. Not only will this genetic sleuthing help shed light on some of the koala's unique biological quirks, it will also help efforts to protect the increasingly threatened marsupials.  

The research team, which included Dr Rebecca Johnson from the Australian Museum Research Institute as well as Queensland University of Technology's Professor Peter Timms, has effectively produced a "genetic instruction manual" for the species. 

"A gene is a segment of DNA that holds the instructions to make proteins, the building blocks of life. Previously, fewer than 100 koala genes had been identified by scientists. This new publication reports on the identification of approximately 15,000 koala genes (i.e. the koala ‘transcriptome’), representing all the genes that were 'switched-on' in the koalas sampled. This is only the third transcriptome to be obtained from a marsupial," the researchers explain.

The team sampled genetic material from two koalas, a male and a female, and was able to identify the switched-on genes in a range of different koala tissues, including spleen, liver, uterus, kidney, lung, heart, brain, adrenal gland, bone marrow, lymph node, salivary gland and testes.

The data obtained should help scientists answer questions about some of the more unusual aspects of koala biology – like how these eucalyptus-loving marsupials are able to survive on such a highly specialised leafy diet (eucalyptus leaves are not only very fibrous and low in nutrition, they're also poisonous to most other animals).  

In addition, the team hopes their genetic discoveries will help drive koala conservation. According to the Australian Koala Foundation, the animals are in serious decline, with estimates putting population numbers at fewer than 80,000 (and possibly as few as 43,000).

Aside from habitat loss and threats posed by dog attacks and collisions with vehicles, koala populations are also being ravaged by diseases like chlamydia and an AIDS-like virus known as KoRV (koala retrovirus). The virus, which has been detected in 100% of the animals in some areas, is thought to weaken the marsupials' immune systems, making them more susceptible to infections and cancer.  

"The koala transcriptome will ... significantly improve the conservation of koalas by transforming our understanding of koala immune genes and the koalas’ response to the diseases that currently threaten many populations," say the researchers.

The team also hopes to tap into new and detailed knowledge about genetic diversity among koala populations, allowing them to assess the impact of threats such as habitat fragmentation on the species.

"This will significantly improve our ability to manage wild and captive koala populations," the team notes.

Top header image: Justin Brown, Flickr