Marsupial bones and worms’ brains
At day two of Fresh Science, meet two researchers from Sydney
Two tiny fossils are set to overturn the conventional theory about the evolution of marsupials, which holds that there was a single migration from the part of the Gondwana ‘supercontinent’ that became South America to the part that became Australia.
“The origins of Australian marsupials suddenly got a lot more complicated!” says palaeontologist Dr Robin Beck, an ARC DECRA postdoctoral fellow at the University of NSW.
How worms and their genes could help us understand dementia and ageing.
The discovery of a link between a specific gene and ageing in a species of worm could reveal valuable lessons for the treatment of Alzheimer’s disease.
Low levels of the protein generated from the gene known as ‘tau’—also present in humans—not only hastens age-related changes in the brain of the worm, but also shortens the worm’s life, Sydney University PhD candidate Yee Lian Chew has found.
These two stories are being presented at Fresh Science. Twelve early-career scientists are unveiling their research to the public for the first time in Melbourne this week and in coming weeks.
Let me know if you’d like to hear more about any of these stories – read more below.
Kind regards,
Niall
- Tiny fossils link ‘old bastard’ marsupials to South America and Africa
- Worms reveal link between dementia gene and ageing
- Still to come at Fresh Science
Tiny fossils link ‘old bastard’ marsupials to South America and Africa
Two tiny fossils are prompting an overhaul of theories about marsupial evolution after they revealed unexpected links to South America – and possibly Africa.
One of the fossils, found at the Tingamarra site in south-eastern Queensland, is a 55 million-year-old ankle bone from a mouse-sized marsupial previously known only from South America. The second is a tooth, which derives from a formerly unknown species that shows similarities to fossils found in South America and, surprisingly, North Africa.
The two fragments are set to overturn the conventional theory about the evolution of marsupials, which holds that there was a single migration from the part of the Gondwana ‘supercontinent’ that became South America to the part that became Australia.
“The origins of Australian marsupials suddenly got a lot more complicated!” said palaeontologist Dr Robin Beck, an ARC DECRA postdoctoral fellow at the University of NSW.
“All the species of modern day marsupials here are quite closely related. The species represented by the ankle-bone belongs to an entirely different group – a group that we know lived in South America but, up until now, we thought never made it to Australia.
The tooth is more of a mystery: are its origins in South America, Africa or somewhere else?
“It is impossible to explain the presence of these new fossils in Australia using the single dispersal model. Instead, there may have been multiple movements of marsupials between South America and Australia.”
Because the fossil tooth comes from a species previously unknown to science, Dr Beck had the honour of formally describing and naming it. His paper on the subject has been accepted for publication this year in the journal Acta Palaeontologica Polonica.
“I’ve named it after one of my colleagues, Henk Godthelp, who has led research at Tingamarra together with Mike Archer and Sue Hand,” he explained. “Henk’s nickname is ‘The Old Bastard’, so I’ve called the species Archaeonothos henkgodthelpi, which translates, roughly, to ‘the ancient illegitimate of Henk Godthelp’. The name also implies the species is unrelated to other Australian marsupials.”
The similarities between the fossil tooth and those of an extinct species recorded in Tunisia remain the tantalising subject of further research. For the moment, though, Dr Beck thinks the tooth and the ankle-bone – which he described in the German journal Naturwissenschaften – provide fascinating new information about the history of marsupials in Australia.
“They mean that extinction has played a much bigger role in the story than we previously thought,” he said. “Some species became extinct in Australia but survived in South America. And perhaps the opposite is also the case – will there be discoveries in South America of typically ‘Australian’ fossils?”
Dr Beck said climate change might have played a role in the disappearance of the ‘ameridelphian’ marsupials. The Tingamarra fossil deposits date from 55 million years ago, when the climate was very warm. “It would have been lush rainforest,” he said. “Since then, the climate in Australia has been gradually cooling.”
Dr Beck is one of 12 early-career scientists unveiling their research to the public for the first time thanks to Fresh Science, a national program sponsored by the Australian Government through the Inspiring Australia initiative.
For interviews:
- Niall Byrne, 0417 131 977, niall@scienceinpublic.com.au
University contact:
- Deborah Smith, 02 9385 7307, deborah.smith@unsw.edu.au
Worms reveal link between dementia gene and ageing
The discovery of a link between a specific gene and ageing in a species of worm could reveal valuable lessons for the treatment of Alzheimer’s disease.
Low levels of the protein generated from the gene known as ‘tau’—also present in humans—not only hastens age-related changes in the brain of the worm, but also shortens the worm’s life, Sydney University PhD candidate Yee Lian Chew has found.
“We found that worms lacking tau lived almost one third shorter than worms that have tau, providing startling evidence that the gene is important in regulating overall lifespan,” said Yee Lian.
Her findings – together with related experiments on mice and other models – could be very important for future Alzheimer’s Disease treatments.
“One theory of dementia suggests that lowering the activity of this gene in a patient will lead to some degree of cognitive improvement,” she said. “However, too little is also bad. It needs to be a balance.”
Yee Lian’s work at the university’s School of Molecular Bioscience uses a species of nematode worm called Caenorhabditis elegans, which is see-through and just one millimetre long.
The worms are an exceptional way to study brain ageing, she says, as their transparency allows her to easily examine the changes that emerge in older brain cells and to study how fast the brain ages.
“Humans are certainly more complex than worms, but at a molecular level there are many striking similarities,” Yee Lian says. “The lack of complexity is also an advantage – worms have 302 brain cells whereas humans have billions. It is much simpler to study brain ageing in an animal where individual cells can be easily observed.”
In humans, aging is associated with subtle changes in the brain. These changes are comparable to those observed in worm brains, such as the growth of structures called branches and beads along nerve fibres known as axons.
“Our most exciting discovery is that worms lacking tau display these abnormal structures at early and middle age, while normal worms that have tau only show these structures late in life,” said Ms Chew.
“This suggests that the lack of tau causes worm brain cells to age faster.”
The discovery, which was published in the Journal of Cell Science, may lead to valuable clues for the treatment of Alzheimer’s Disease, a devastating condition which affects one in four people over the age of 85.
“Our research provides an important stepping stone towards the ultimate goal of improving diagnostic tools and treatments for those suffering from this condition,” she said.
Ms Chew is one of 12 early-career scientists unveiling their research to the public for the first time thanks to Fresh Science, a national program sponsored by the Australian Government through the Inspiring Australia initiative.
For interviews:
- Niall Byrne, 0417 131 977, niall@scienceinpublic.com.au
University contact:
- Verity Leatherdale, University of Sydney, 02 9351 4312, verity.leatherdale@sydney.edu.au
Still to come at Fresh Science
Tomorrow, you’ll hear about how algae could prove the key to cheaper and more efficient production of alternative fuel.
Despite the claims of some, commercially viable fuels from algae have not yet been developed. But newly trialled native algae species provide real hope, a Queensland scientist has found.