World-first echidna, improved platypus genomes mapped

The first ever echidna genome and a greatly improved, high-quality platypus genome have been sequenced by an international team of researchers.

The findings, published in Nature, were produced by 40 researchers from Australia, China, Japan, the US, and Denmark, including from the University of Sydney.

University of Sydney lead, Professor Katherine Belov from the School of Life and Environmental Sciences, said that through this research, she and the team “discovered new peptides” in both the platypus and echidna genomes. These peptides have the potential to be developed into novel drugs for humans and other animals due to their potent antimicrobial activities. “Their potential for biomedical applications is so exciting,” Professor Belov said.

“Platypuses and echidnas are humans’ most distant, living mammalian relatives. Their ancestors lived alongside dinosaurs, about 180 million years ago,” said study co-lead, the University of Adelaide’s Professor Frank Grutzner.

“The new genomes are a hugely valuable public resource for research into mammalian biology and evolution. This also has other important applications, for example, in human health and wildlife conservation.”

Female platypuses don’t have teats. Rather, they secrete milk onto their bellies for their babies to lap up. “We believe that the novel antimicrobial peptide genes that we found are secreted by mothers through their milk, to protect their young from harmful bacteria while they are in burrows,” Professor Belov said.

A similar process also occurs in echidnas. Newborn platypus and echidna do not have immune tissues or organs when they hatch from eggs. Their immune systems develop while they are in burrows.

These findings build on Professor Belov’s prior, genomic research on the platypus, which pinpointed the genes responsible for the animal’s venom. Future work will involve measuring the antimicrobial activities of each platypus and echidna peptide against a broad panel of bacteria and viruses, to identify the best targets for future development.

Researchers from other Australian universities, including the University of Melbourne, focused on identifying and studying genes responsible for platypus lactation in order to understand mammals’ evolutionary transition from egg-laying to live birth.

The platypus is considered ‘near threatened’, with several local populations already extinct. Though not threatened, the echidna has also suffered some local extinctions because of road deaths and habitat destruction. Recent, further habitat destruction, including due to the 2019-2020 bushfires, has hastened population declines. Not only does this mean fewer animals; it also means less genetic diversity, which weakens and therefore threatens the evolutionary potential of these species.

The researchers hope to remedy this using the results of their study to inform genetics-based breeding programs. “Not only can animals be bred based on their genetic compatibility; individuals with greater capacity to adapt to a changing environment can be selected for such breeding,” Professor Belov said.

Hero image credit: Gary Ramage.

Declaration: Work was supported by the Strategic Priority Research Program of the Chinese Academy of Sciences, the National Key R&D Program of China, International Partnership Program of Chinese Academy of Sciences, Carlsberg foundation and Villum Foundation, the National Natural Science Foundation of China, Natural Science Foundation of Zhejiang Province, European Research Council Starting Grant, start-up funds from Zhejiang University, and the Australian Research Council.

• Monotremes are the only mammals that lay eggs instead of birthing live young.
• Despite being mammals, they have some reptilian features: some of their bones resemble those of reptiles, and, like reptiles (and birds), they have a cloaca, with only one external opening for excretion and reproduction, whereas other mammals have separate systems for each.