Genetic study of our national icons

Research

Most of us hold a picture of this animal in the palm of our hand every day. But few realise what an amazing creature the platypus is.

The Australian icon pictured on our 20 cent coin may hold the answers to many questions puzzling evolutionary biologists the world over.

For the past five years, University of Adelaide geneticist Dr Frank Grützner has devoted his time to solving the mysteries of the platypus's genes and chromosomes. Why? Because this unique monotreme could give us some invaluable insights into the history of our own genes.

One has to go back 210 million years to find the last common ancestor between humans and the platypus, the earliest known branch in the mammalian lineage.

"Evolution filters out important genes," Dr Grützner says. "By studying the platypus we can probably find the genes that play a crucial role in our own development."

The platypus is unique for a number of reasons.

"They are egg laying, which is extraordinary for a mammal. They are venomous, they regulate their body temperature at 32 degrees - not 37 as most other mammals - and their reproductive system is a mixture of reptilian and mammalian. Their sperm looks exactly like chicken sperm. There's a whole raft of extremely interesting stories with the platypus.

"There are still a lot of holes in our knowledge of the sex-determining genes in humans. If we can work out what is going on with the platypus, it could tell us something relevant to humans and fill some of those gaps," Dr Grützner says.

The whole platypus genome is currently sequenced in the United States. Dr Grützner's lab in Adelaide and the Australian National University are collaborating with the US on this sequencing project.

But there are some major disadvantages with using the platypus as a model for genetic research, which is why scientists are now looking to the echidna for answers.

"Keeping and breeding the platypus has been a huge problem. In this respect the echidna is a much better choice. Echidnas are also found throughout Australia, whereas platypuses are contained mainly to eastern Australia."

Dr Grützner from the University's School of Molecular and Biomedical Science, Dr Peggy Rismiller from Anatomical Sciences, Dr Greg Johnston from the Royal Zoological Society of South Australia and Professor Steve Donnellan from the SA Museum are about to launch a collaborative echidna project.

"We want to integrate state-of-the-art radio tracking and molecular genetic techniques that we have established in the platypus to give us an in-depth insight into behaviour and ecology of the echidna.

"A combination of field work and molecular work and a unique combination of expertise in this collaboration will reveal unprecedented insights into the biology of these enigmatic and iconic animals," Dr Grützner says.

Dr Grützner joined the School of Molecular and Biomedical Science at the University of Adelaide in 2005 as a lecturer and took up an ARC Australian Research Fellowship in 2006.

Originally from Germany, he completed his PhD at the Max Planck Institute for Molecular Genetics in Berlin. In 2001 he secured an ARC Postdoctoral Fellowship with Professor Jenny Graves at the Australian National University, studying reptiles, marsupials and monotremes.

Dr Grützner is continuing his research into platypus and echidna in Adelaide as well as other animal systems like reptiles and cattle.

Story by Candy Gibson