Recent and significant scientific developments and publications

 

Ancient remains

Remains of Tasmanian devils that are thousands of years old could hold clues about how to deal with the Devil Facial Tumour Disease (DFTD).

Dr Jeremy Austin, an evolutionary biologist from the University of Adelaide, received funding in October 2008 from the Australian Research Council (ARC) to examine the genetic diversity of ancient devil remains.

This work builds on the findings of scientists in the Save the Tasmanian Devil Program, who previously determined that DFTD is a contagious cancer. It can spread between individuals because of a lack of genetic diversity among Tasmanian devils.

‘We want to understand when, where and why Tasmanian devils lost genetic diversity,’ Jeremy said. ‘Some of the samples we have from Victoria and Western Australia go back thousands of years. They’ll be able to give us an indication of how genetically diverse devils were, and whether they’ve been through something like this before.’

The ultimate goal of this research is to develop a screening program that identifies devils with a higher genetic diversity. These devils are the animals that will most likely be immune or resistant to the Devil Disease.

 

New strains of DFTD emerging

The Devil Facial Tumour Disease (DFTD) is evolving in the wild, according to research undertaken for the Save the Tasmanian Devil Program.

In July 2008, Anne-Maree Pearse, a cytogeneticist with the Tasmanian Department of Primary Industries and Water, said a project undertaken at the Mt Pleasant Laboratory had identified several different strains of the transmissible cancer.

"We had a basic understanding of the disease, but we knew it was important to monitor and track its behaviour over time," Mrs Pearse said. "Our earlier research, identifying that DFTD is a transmissible cancer, highlighted the fact that we’re up against a very unusual type of cancer.

"So we established a project to monitor and understand the evolution of DFTD. It’s out of this project that we’ve discovered more about the unusual nature of this disease."

Staff at Mt Pleasant identified several different cytogenetic strains of DFTD. They are now trying to establish if those strains have behavioural differences in the way they affect Tasmanian devils.

"Our preliminary findings indicate that the early strains of DFTD are becoming unstable and may be under selective pressure to transform," Mrs Pearse said.

"Our concern is that although the disease has much more potential to evolve and develop these different strains, the devil itself doesn’t have the same potential. It doesn’t seem to be able to adapt and respond to the changing disease types.

"What that means is that while some animals may have some immune response to the disease now, we don’t know whether they will be immune to all the different strains of the disease."

Mrs Pearse said there was further work being undertaken to understand the evolving disease.

"All of this again highlights the reality that there isn’t a single, simple solution to managing the impacts of the devil disease," Dr Pearse said. "We’re dealing with a highly complex cancer type, and it is continuing to evolve. We need to continue to monitor its behaviour, and take that into account as we identify management options."

 

The diet of devils

Recently-published research into the diet of the Tasmanian devil will be important for the management of wild and captive devil populations, as well as in helping us to understand the devil’s place in the environment.

‘The diet of the Tasmanian devil, Sarcophilus Harrisii, as determined from analysis of scat and stomach contents’, by David Pemberton et al, was published in the Papers and Proceedings of the Royal Society of Tasmania, Vol. 142(2), 2008.

The research - based on scats founds at six different sites, as well as the stomach contents of seven devil roadkills - found that mammals, birds, fish, insects and plant material were all part of the Tasmanian devil’s diet. But it’s mammals that made up more than 60 per cent of the diet, with Common Ringtail Possums, Pademelons and Bennett’s Wallaby being the species that contributed most significantly.

‘To date, we’ve had only limited understanding of the diet of Tasmanian devils,’ said Dr David Pemberton, Program Leader within the Wildlife and Marine Conservation Section of DPIW and co-author of the book ‘Tasmanian Devil: A unique and threatened animal.’

‘So our study was to further our understanding of the ecology of this threatened species, as well as provide important information for its management. It’s fascinating to realise that devils usually have a mixed feed, and that this often contains birds and mammals.’

The Papers and Proceedings of the Royal Society of Tasmania are available in libraries.

 

Devils breeding early in response to DFTD

Tasmanian devils are breeding early in response to the Devil Facial Tumour Disease (DFTD), scientists from the Save the Tasmanian Devil Program have discovered.

In a paper published in July 2008 in the US journal, Proceedings of the National Academy of the Science (PNAS), the researchers explain that this is the first known case of infectious disease leading to increased early reproduction in a mammal.

The scientists outline data from five Tasmanian study sites to show that a majority of female devils are responding to the disease by breeding when they are one-year old, instead of the usual two years. And instead of breeding about three times in a lifetime, most are breeding only once before they die.

"We have found that devils are compensating for the disease by breeding early," said Dr Menna Jones, wildlife management officer with the Save the Tasmanian Devil Program. “There is a 16-fold increase in the number breeding at the age of one year.

"The devils are under intense selection for early breeding because the disease is 100 per cent fatal. Any devil that’s successful in breeding more than once is putting out more of its genes into the pool of survivors."

Scientists conjecture that the early breeding may have been encouraged by the greater abundance of food available to the lower density of surviving devils.

The paper was researched by Dr Jones and her PhD student, Shelly Lachish; Professor Hamish McCallum, Rodrigo Hamede, Heather Hesterman, UTAS; Professor Andrew Cockburn, ANU; Clare Hawkins, Diana Mann, David Pemberton, Department of Primary Industries and Water.

Facts on the adaptation of Tasmanian devils, taken from the research paper, "Life-history change in disease-ravaged Tasmanian devil populations".

• Scientists analysed data from five devil populations where individually marked devil populations have been studied both before and after the arrival of the DFTD.
• The disease has had highly significant effect on the age structure of devil populations at all five sites. More older animals were present in the population before the disease: many fewer older animals were found post-disease.
• Before DFTD, female devils began seasonal breeding at age two, produced a litter annually for three years and died aged five or six. Records of early breeding are rare. Post-DFTD, females are largely semelparous – that is, have only one breeding opportunity.
• Substantial increases in early breeding by one year-old females occurred at four of the five sites. At the fifth site, Little Swanport on Tasmania’s East Coast, a cause for the lack of increase in early breeding cannot be determined given the snapshot nature of the data. It may be due to chance.
• Any ability in devils to increase lifetime reproductive output beyond one litter, or even rear a single litter to independence before death from cancer, should also enhance the fitness of those individuals.
• Although the ability to switch to early reproduction offers some prospect for persistence and recovery, the prognosis of this iconic species remains uncertain.

 

A lack of genetic diversity

Collaborative research across Australia has provided further evidence that a lack of genetic diversity among Tasmanian devils is a key factor in the transmission of Devil Facial Tumour Disease (DFTD).

The latest findings, published online in the Proceedings of the National Academy of Sciences, built on earlier research into the immune systems of Tasmanian devils. DFTD is extremely rare as it’s only one of three recorded cancers that can spread like a contagious disease.

"Devils in eastern Tasmania do not mount an immune response against DFTD," said Dr Katherine Belov, from Sydney University’s School of Veterinary Science.

"This is due to a loss of genetic diversity in the most important immune gene region of the genome: the Major Histocompatibility Complex (MHC).

"In the case of devils from eastern Tasmania, genetic diversity at the MHC is so low, and the MHC type of tumour and host are so alike, that the host does not see the tumour as ‘non-self’."

The research brought together scientific staff from Sydney University, the University of Tasmania’s Menzies Research Institute, the Department of Primary Industries and Water (Tasmania), the Australian Museum and Macquarie University (NSW).

"We now have a tool to measure immune response genes and we are now in search of devils whose MHC might be different from the MHC of the tumour," said Dr Greg Woods, Associate Professor Immunology at the Menzies Research Institute.

"This knowledge could then be used to alert the devil’s immune system to recognise the cancer cells as foreign.

"This will then persuade the devil’s immune system to destroy these cancer cells."

 

Update on toxicological investigations

Independent assessments of toxicological data from healthy devils and devils suffering from Tasmanian Devil Facial Tumour Disease found that a chemical cause of the disease is unlikely.

The two reports (see links below) also indicated that although levels of dioxin and other chemicals were detected in devil tissues they were at levels to be expected for a top of the food chain species such as the Tasmanian devil.

None of the chemicals measured were at significantly different levels in diseased and healthy animals and there was no evidence that any of the chemicals are linked to DFTD.

The assessments were undertaken as one part of the research into possible causes of the disease and simply help guide ongoing investigations in this field.

The two assessments were undertaken by Dr Tony Ross, a specialist veterinary pathologist with a strong background in toxicology and Professor Michael Moore, the Director of the National Research Centre for Environmental Toxicology.

In his report, Dr Tony Ross says a small number of chemicals may warrant further investigation including arsenic and some of the brominated diphenyl ethers.

He states that although the results will be of interest to some scientists, they do not show a link between chemicals and DFTD.

The next stage of this area will involve further discussions with scientific staff involved in the project, and the independent toxicologists to identify any other areas that may need further examination in relation to the disease.

Reports:

Opinion on a chemical aetiology for facial tumor development in the Tasmanian Devil (PDF, 83 KB)

Persistent Chemicals in Tasmanian Devils (PDF, 214 KB)

 

Using genetics to guide selective breeding

An integrated research program is needed to describe the Tasmanian devil genome and determine how to overcome the problem of low genetic diversity in the population, a genetics workshop at the University of Tasmania concluded in November 2007.

Internationally-recognised genetics and cancer experts made these recommendations based on what has been learned from the cheetah and mammoth. Like the devil, the survival of those species was compromised by low genetic diversity.

The photograph shows (rear, l - r) Paul Humphrey (University of Tasmania), Greg Woods (Menzies Institute), Stephen Schuster (Penn State University, USA), Menna Jones (University of Tasmania), Hamish McCallum (University of Tasmania), Steve Smith (DPIW); (front, l - r) Jeremy Austin (University of Adelaide), Vanessa Hayes (Garvan Human Cancer Institute, NSW), Kathy Belov (University of Sydney), Shelly Lachish (University of Queensland).

“There is a lesson to be learnt from extinct species,” said Professor Stephen Schuster, from Penn State University in the United States, who is currently analysing the genome of the extinct mammoth. “We should not wait for one or two years to begin working on the devil.”

Dr Vanessa Hayes, head of the Cancer Genetics Group at the Garvan Institute of Medical Research in NSW, said the cheetah is a perfect comparison to the devil.

“The cheetah was headed for extinction due to in-breeding and low genetic diversity until genetics was used to guide selective breeding,” she said. “That project has been a wonderful success, and the cheetah is being saved."

Adelaide University’s Dr Jeremy Austin is an expert in DNA studies of extinct species, including the thylacine. “We know what is needed,” he said. “We have the expertise from studies on other species, and now we need to use the new DNA sequencing tools to save this species from extinction.”

Dr Kathy Belov, from the University of Sydney, recently discovered that some western devils are genetically distinct from eastern devils.

Ecohealth journal article - September 2007

The Tasmanian Devil Facial Tumour Disease (DFTD) was the special focus of the September 2007 issue of the international, peer-reviewed journal, EcoHealth (www.ecohealth.net), which focuses on ecology, human health, global climate change, and conservation medicine..

“This crisis is exactly why we launched our journal five years ago,” said Dr Bruce Wilcox, editor-in-chief of EcoHealth. “We focus on the connections between ecology and health, and here’s an example where a disease threatens the imminent extinction of a keystone species.”

The journal featured articles written by members of the Save the Tasmanian Devil Program and collaborative partners, covering key issues of DFTD definition, impacts, conservation management, and physiological response.

Click on the titles to read the following papers published in Ecohealth:

• Towards a Case Definition for Devil Facial Tumour Disease: What is it? (PDF, 191 KB)
• Distribution and Impacts of Tasmanian Devil Facial Tumour Disease (PDF, 301 KB).
• Conservation Management of Tasmanian Devils in the Context of an Emerging, Extinction-threatening Disease: Devil Facial Tumour Disease. (PDF, 235 KB).
• The Immune Response of the Tasmanian devil and the Devil Facial Tumour Disease. (PDF, 314 KB).

See also: Editorial (PDF, 104 KB), Cover Essay (PDF, 91 KB), and In This Issue (PDF, 89 KB).

The journal, EcoHealth, is one aspect of the work of U.S.-based Wildlife Trust – a group founded in 1971 to empower local conservation scientists worldwide to protect nature and safeguard ecosystem and human health.

Wildlife Trust pioneered the field of Conservation Medicine, a new discipline that addresses the link between ecological disruption of habitats and the effects on wildlife, livestock and human health (www.conservationmedicine.org) through inter-disciplinary collaboration amongst doctors, veterinarians, public health workers, statisticians, ecologists, geologists, and other scientists and policy makers. "In the case of Tasmanian devils," said Mary Pearl, President of Wildlife Trust, "here's another textbook example of an emerging infectious disease bringing the proximate cause of a species' extinction."

A contagious cancer

The Devil Facial Tumour disease is a remarkable cancer as it is one of only three recorded cancers that spread like a contagious disease. Under normal circumstances cancer cannot be “caught” as the cancer cells from one host are completely different to the next host and should be rejected by the immune system.

Since DFTD breaks this rule, there are many questions which need to be answered to explain how this cancer can be spread from devil to devil. One of the most important questions relates to their immune system.

Researchers at the Menzies Research Institute, led by Associate Professor Greg Woods, are currently undertaking studies to investigate whether Tasmanian devils have a fully functional immune system. PhD student, Alex Kreiss (see photo), has taken many blood samples from Tasmanian devils and subjected these samples to laboratory tests of immune function, similar to tests that are performed in normal pathology laboratories that investigate human blood samples. Alex has shown that our Tasmanian devils do have a good immune system as they have the correct mix of white blood cells and the lymphocytes, the key cell in the immune system, function normally.

These laboratory tests were then extended to analyse the immune response of the Tasmanian devil directly. This required injection of red blood cells under the skin of a number of Tasmanian devils. This was performed with the assistance of experienced veterinary surgeon, Dr Barrie Wells. Results of these studies were even more conclusive confirming that Tasmanian devils have a functional immune system as the devils rapidly produced antibodies in response to the foreign red cells.

We are therefore confronted with the perplexing problem that DFTD can develop in animals with a fully competent immune system. This is an immunological conundrum and further investigations were undertaken to determine why the devil facial tumour cells are not recognised by the immune system. The devil to devil transmission suggests that this cancer is similar to a transplant, but rather than a transplant of a life saving organ such as a heart or kidney, the transplant is a life threatening cancer.

Mixed lymphocyte reactions were then undertaken to investigate whether the Tasmanian devil has the correct genes to allow recognition of foreign cells. This was performed by mixing lymphocytes from many devils to see if they reacted to each other. The results from these studies clearly showed that devils failed to recognise cells from other devils as different. This provides strong evidence that a lack of genetic diversity contributes to why the cancer is infectious. Therefore when a healthy devil is infected with a devil facial tumour from another animal, the infected devil’s immune system assumes that the new cancer cells are the same as its own cells and will not reject it.

The daunting task ahead is to learn how to persuade the devil’s immune system to recognise the cancer cells as hostile infectious agents, which will then alert the devil’s immune system to destroy these cancer cells.

A facial tumour that appeared to shrink in an “interesting” devil

A diseased Tasmanian devil with a facial tumour that appeared to shrink is among the interesting animals caught by our population monitoring team at Fentonbury, in the State’s south. Photographs of this two-year-old female show that her facial tumour appeared to decrease in size over a three- to six-month period. Sadly, however, the tumour then increased again, killing the animal.

“We have to exercise a bit of caution in saying that this is definitely evidence of tumour regression in an individual,” said Billie Lazenby, a scientific officer with the Department of Primary Industries and Water. “Some people might say that the tumour just changed shape, or maybe that part of the tumour fell off. But it definitely looked smaller.

“So it’s important for us to know whether this is normal. Do some individuals just have a much better capacity to cope with the disease? Or do they have a less virulent strain of the disease? Or do they have a better immune response? These are the key questions.” Why was this devil “interesting”? Fentonbury is one of the most intensely monitored of all our trapping sites across Tasmania, with field trips occurring over a 10-day period, four times per year. Of the 46 diseased animals that Billie Lazenby has marked since she started working there in June 2004, she’s only recaptured 10 more than once. Once an animal gets DFTD, that’s basically it. Of the 10 diseased animals caught twice, only two individuals have been caught more than twice – the devil with what appeared to be a shrinking tumour, and a second female, which was three years old. Remarkably, both diseased animals successfully weaned their young before being overwhelmed by the cancer. “One of the advantages of a long-term ecological monitoring program is that we could follow the progress of pouch young from these interesting females,” said Billie. “They could have something special, so we also take blood and tissue samples to study the reason for their apparent longevity.” Other points of interest from the Fentonbury site include the fact that eight of the 10 diseased devils that were caught twice were female. This may have to do with the fact that females have smaller home ranges, and are more likely to be trapped twice.

Cold Spring Harbor Laboratory, New York

Dr Elizabeth Murchison and colleagues at New York’s Cold Spring Harbor Laboratory are using new DNA sequencing technologies to discover the genes that cause DFTD. Cold Spring Harbor Laboratory is a world centre for molecular biology research. It is home to Nobel Prize winner James D. Watson who, together with Francis Crick, discovered the double helix structure of DNA. Cold Spring Harbor continues to be at the cutting edge of DNA research. Elizabeth and her group are using new DNA sequencing machines to identify chromosomal rearrangements in DFTD and to sequence DFTD cancer genes. “This work will help us to understand more about DFTD at the molecular level,” says Elizabeth. “This may lead to the discovery of a DFTD diagnostic test and information that can help with the devil conservation effort.” Devil genome sequence information generated at Cold Spring Harbor Laboratory will be freely available on the internet to all DFTD scientists. “The sequences will be a useful resource for everyone,” says Elizabeth, “and we hope that it will accelerate the global effort to save the devil”.

July 2007 - Genome sequences

Dr Kathy Belov, from the University of Sydney, is hoping her recent work with genome sequences will lead to a better understanding of the Tasmanian devils’ immune responses to facial tumours. Dr Belov was among 11 Australians taking part in a recent international study led by the leading genomic research centre, the Broad Institute in Boston. The US research team sequenced the genome of the South American opossum - the first time scientists had done so for a marsupial. Dr Belov was involved in the painstaking task of comparing the genetic information revealed about the opossums’ immune system with that of humans by using highly complex algorithms, or mathematical formulae, on computers.

'We think that having this basic information about the immune system of one marsupial will really help us to understand the immune responses of other marsupials,' Dr Belov said.

The researchers are now working to compile the genome sequence of the Tammar wallaby. Armed with immune gene sequences from just "one or two" marsupial species, scientists will be able to rapidly characterize immune genes in the devil and measure the immune responses to tumours in the Devil Facial Tumour Disease. This would allow them to identify difference between animals which recover from the tumours, or have a slower disease progression and those that succumb quickly.

'That would certainly help us understand the immunology of the tumour and hopefully come up with a cure in the long term,' Dr Belov said.

CSIRO Scientific Research - May 2007

CSIRO scientists have joined the battle to save Australia’s iconic Tasmanian devils from the deadly cancer devastating the devil populations. Researchers from CSIRO’s Livestock Industries Australian Animal Health Laboratory (AAHL), Textiles and Fibre Technology and Land and Water are working together to hunt down the cause of the Devil Facial Tumour Disease (DFTD) and to establish how far the disease has spread. The integrated research group at AAHL will use a variety of techniques including microscopy, microarrays and a range of molecular techniques to search for infectious agents, markers for disease and to determine where the tumour originates from. “We will be working in a number of areas including establishing whether a virus or other infectious agents are associated with the tumours,” AAHL’s Dr Alex Hyatt, said. “If successful the establishment of pre-clinical tests will allow researchers to remove known infected devils, in turn limiting the spread of the disease.” Dr Jeff Church, a chemist and Spectroscopist at CSIRO Textiles and Fibre Technology, is investigating the Tasmanian devil’s hair to determine if any chemical or structural changes can be detected that can be correlated with the disease. “We are hoping we can work together to develop a pre-clinical diagnostic test based on recent developments in the diagnosis of human breast cancer,” Dr Church said. “Such a test would enable the screening of captured animals prior to their release into the wild or placement into isolated breeding populations.” Mr Steve Marvanek, Spatial Data Analyst at CSIRO Land and Water, recently integrated historical wildlife spotlight data, devil monitoring data and geo-referenced reports of diseased devils into a geographical information system (GIS) to map the spatial and temporal distribution of the disease across Tasmania.

A case definition of Devil Facial Tumour Disease - November 2006

Tasmanian Department of Primary Industries and Water (DPIW) veterinary pathologist Dr Richmond Loh, in conjunction with Murdoch University, published a case definition of the Tasmanian devil disease in the November edition of Veterinary Pathology (Abstract). The publication reported that there was little difference in the tumours across their range, that they affect both male and female animals equally, and that they are very aggressive local cancers that have metastasised in more than 60% of cases.

The origin of tumour cells - November 2006

Research into the origins of the tumour cells by DPIW veterinary pathologist, Dr Richmond Loh, in conjunction with Murdoch University, was published in the November edition of Veterinary Pathology (Abstract). This research supports the hypothesis that the cells are of neuroendocrine origin. Although DFTD was once thought to be a variant of lymphosarcoma, and a retrovirus was considered a possible cause, this research provides evidence to the contrary.

Managing an emerging disease threat - October 2006

The Public Library of Science Biology recently published the work of Dr Menna Jones and Professor Hamish McCallum of the University of Tasmania. Their paper uses the Devil Facial Tumour Disease as a case study on managing an emerging disease threat. It highlights the need to make management decisions with imperfect knowledge and the importance of continuously managing the known risks. The paper examines the range of options for managing the disease threat.

The impact and distribution of the Tasmanian Devil Facial Tumour Disease - July 2006

The August 2006 edition of Biological Conservation, (available online from Science Direct www.sciencedirect.com), published research by scientists from a range of institutions, co-ordinated by DPIW wildlife biologist Clare Hawkins. The research brought together results from all the field monitoring that has been undertaken as part of the program. It also combined data from annual spotlighting surveys over the last decade, and historical records of devil trapping, to give an overall picture of the changing distribution of Devil Facial Tumour Disease and its impact on Tasmanian devil populations.

Clones transmitted by allograft - February 2006

Senior cytogeneticist with the Department of Primary Industries and Water (DPIW), Anne-Marie Pearse, and her assistant, technician Kate Swift, published ground-breaking research on the Tasmanian Devil Facial Tumour Disease (DFTD) in the world's pre-eminent peer-reviewed science journal, Nature. The paper establishes with a high degree of certainty that devil facial tumours are clones transmitted by allograft. Allograft is where tissue is transplanted from a donor of the same species, but different genetic make-up, without the recipient's immune system rejecting the graft. This is an exceptionally rare occurrence.

Full list of recent scientific publications (PDF, 38 KB)

Recent Public Lecture series recordings

Newsletters

Newsletters produced by the Devil Facial Tumour Disease Program will keep you informed about the progress being made in response to the disease.
August 2007 (PDF, 1.17 MB)
May 2007 (PDF, 752 KB)
February 2007 (PDF, 897 KB)
December 2006 (PDF, 621 KB)
March 2006 (PDF, 906 KB)

Research and Scholarship Grants

The University of Tasmania Foundation nominates and allocates a number of scholarships and research grants bi-annually through the Tasmanian Wildlife Research Advisory Committee (TWRAC) for research into the facial tumour disease currently devastating Tasmanian devil populations. (Information on recent recipients is available on our Schools page.) These awards are funded from public donations received through the Tasmanian Devil Research Appeal Fund. They support key research areas approved by the Devil Facial Tumour Disease Steering Committee, which was formed after the October 2003 workshop of scientists and animal health experts from institutions and organisations throughout Australia. More information on the awards and application process is available from www.utas.edu.au/devilappeal

Latest Spotlighting Data

Each year the Department of Primary Industries and Water undertakes “spotlighting” surveys of a number of native species around the State.
These surveys provide an opportunity to understand whether populations of particular species are increasing or decreasing across the State and in particular areas.Having been conducted over many years, the spotlight data on Tasmanian devils provides an opportunity to understand the declines that have occurred since the emergence of the disease. As previously highlighted in research co-ordinated by Dr Clare Hawkins from DPIW, there had been a Statewide decline of more than 40 per cent in average sightings per spotlighting survey route from 1992-95 to 2002-05. Incorporation of the latest 2006 spotlighting data into this analysis indicates that the devil population is continuing to decrease Statewide. Latest estimate of the decline in Tasmanian devils since the first report of the disease (spotlighting survey results compared from 1992-95 to 2003-06) shows the Statewide decline in sightings is now 53 per cent. In specific areas where the disease has been recorded for longest the declines are more dramatic. For example in the north east, where the disease was first reported, the sightings have declined by 89 per cent from 1992-95 to 2002-05.

Would you like to know more?

See the Science of Devil Facial Tumour Disease information on the Tasmanian Department of Primary Industries and Water website.

View a movie on the Tasmanian devil and the race to prevent its extinction.