Australasian Science: Australia's authority on science since 1938


By Stephen Luntz

Hormones combine against obesity, antioxidants don’t aid conception, a drug prevents breast cancer relapse, and more.

Parrots Alive

DNA analysis of five feathers collected in the Lake Eyre Basin have confirmed that the Australian night parrot is not extinct.

Pezoporus occidentalis is a different species from New Zealand’s famous kakapo, but shares both the popular name of night parrot and a critically endangered status. Indeed, WA Museum CEO Alec Coles said: “The night parrot is a bird many people believed to be extinct up until 1990, and the WA Museum is very pleased to have been asked to authenticate its existence”.

The feathers were found by bird enthusiast John Young, who said: “I’ve been tracking these birds for nearly 15 years and I’ve only ever seen them three times. Never before have I been able to get the evidence that would conclusively prove I’d actually found them.”

The site will not be revealed at the request of the property owner.

Hamstring Testing Device

Australia’s sports scientists are outperforming our cricket team, with Queensland University of Technology’s Faculty of Health producing a prototype machine with the potential to save athletes worldwide from hamstring strains.

“Hamstring muscle ‘tears’ are the most common sports injury in the world, with injured players typically missing 3–6 weeks competition and training,” said inventor Dr Tony Shield.

Current hamstring testing devices are expensive and slow, but Shield claimed: “Two of my postgraduate students recently tested a squad of 44 AFL players in 2 hours using the prototype of the QUT device”. Shield’s machine works by measuring the force applied to ankle restraints when athletes perform the “Nordic hamstring curl”, where subjects fall forwards from a kneeling position as slowly as possible.

“Armed with this information a trainer can make a more informed decision on what types of strength training need to be employed, and potentially whether a player is fit to take the field,” said Shield.

Hormones Combine Against Obesity

Two gut hormones that tell the brain it has eaten enough affect different brain regions, so increasing both works better at preventing over-consumption than either alone, Garvan Institute scientists have reported in Obesity.

Pre-clinical trials are underway of the hormones PYY3-36 and PP, both of which reduce fat gain and prevent insulin-resistance in mice. However, the Garvan study is the first to use the two in combination.

“There are many factors that influence appetite control – and we now realise that there won’t be a single molecular target, or a single drug, that will be effective,” said Dr Yan-Chuan Shi. “It will be important for drug companies to try different combinations of targets to see which combinations are most potent and at the same time have no side-effects, or at least minimal side-effects.”

Existing drugs that control eating effectively have side-effects that are usually considered too severe, but low doses of the two hormones may be better.

Antioxidants Don’t Aid Conception

Antioxidant supplements do not increase the chance of conception, according to a review of 28 studies published in The Cochrane Library.

Dietary supplements, including antioxidants, are commonly taken by women seeking to increase their chance of becoming pregnant. However, when Ms Marian Showell of the University of Auckland’s Department of Obstetrics and Gynaecology combined the trials she concluded: “There is no evidence in this review that suggests taking an antioxidant is beneficial for women who are trying to conceive”.

However, Showell warns that the quality of the trials was poor, largely due to small sample sizes. While the collective sample was adequate, the trials used different supplements, leaving open the possibility that some may work.

The women taking supplements were no more likely to miscarry or have ectopic pregnancies than those receiving placebos.

Tamoxifen Prevents Breast Cancer Relapse

Women who carry the breast cancer risk gene mutations BRCA1 and BRCA2 greatly reduce their risk of a second round of cancer if they take Tamoxifen after the first round of cancer.

Tamoxifen has had long-term success in treating certain forms of breast cancer by blocking the oestrogens they need to grow. More recently it has been shown it can prevent the formation of breast cancers, but this study is the first to show a reduced risk for women who carry the two genes that put them in most danger.

“In the past, the only way of reducing breast cancer risk for these high-risk women was to do invasive surgery to remove their breasts and/or ovaries. For women who choose not to undergo such surgery, or who would prefer to delay surgery until they are older, tamoxifen could now be a viable alternative,” said lead author Prof Kelly-Anne Phillips of the University of Melbourne.

The work was published in the Journal of Clinical Oncology.

Fear of Dogs Reduced by Video

A technique known as video self-modelling can help children reduce their fear of dogs.

“Everyone has fears from time to time, but fears can sometimes stop people from doing everyday activities and tasks,” said University of Canterbury Masters student Megan Swney. “Video self-modelling involves someone watching themselves on an edited video doing a target behaviour that they would normally find difficult to do.”

Children in the program read books about the safest way to behave around dogs and watched a video in which it appeared they were at the same location as a dog. They were then taken back to the location, this time with the dog there in real life, and reported feeling less fear than before the program.

Tobacco Harms Insects Too

Tobacco is bad for the health of the environment as well as people. A study of chironomids in the Ovens River found that deformities in these “non-biting midges” decreased once tobacco production in the area ceased.

“We have seen that land managers can make decisions about how they use their land that positively impact aquatic ecosystems because current farming practices in the area are having a lesser impact on the Ovens River,” said Dr Vincent Pettigrove of the University of Melbourne’s Centre for Aquatic Pollution and Identification Management. Pettigrove was co-author of a paper in Agriculture, Ecosystems and Environment on deformities in chironomid mouthparts.

Comparisons were made between 1988–89 and 2010. “The improvement in health of the chironomid is significant as an indicator of river health as they are found in every type of freshwater environment worldwide and are an important food resource for fish,” Pettigrove said.

Consequences of Climate Change

The devastating effect climate change will have on plants and animals has been quantified.

An international study in Nature Climate Change found that two-thirds of 50,000 common species will lose more than half their habitat range by 2080 if emissions of greenhouse gases continue unabated. While polar bears and penguins may be the emblems of climate danger, the study found that plants, reptiles and amphibians were under the most threat and that tropical regions would be “ground zero” for the disaster.

Early action could reduce losses by 60% while providing an extra 40 years for adaptation.

Crocs Vicious as Hatchlings

Crocodiles start fighting each other almost the moment they exit the egg, night vision from infrared cameras has revealed.

Crocodile hatchlings are camouflaged and inactive during the day, making their behaviour hard to study. Charles Darwin University PhD student Matthew Brien collected footage to see what goes on after dark.

“We already know that adult crocodiles have a diverse behavioural repertoire and demonstrate strong parental care like birds, but we have also found that rather than learn their life skills like many other animals they appear to be born with this innate set of behaviours,” said Brien.

“What we discovered is that crocodiles are born with a natural instinct to fight and gain dominance. When I first watched the footage I was shocked to see the baby saltwater crocodiles fighting in the form of head striking and death rolling each other, just like the adults would in the wild and in captivity.”

Australian Climate Stops Sea Level Rising

Major rainfall events can deposit so much water on land that sea levels temporarily stop rising, and Australia is particularly important in this process. Our soils and topography retain water longer than other continents so the effect is more pronounced.

A US National Centre for Atmospheric Research (NCAR) study published in Geophysical Research Letters observed the effects of three enormous downpours during 2010–11, and found it enough to lower ocean height by 7 mm for 18 months, overcoming the 3 mm/year rising trend.

“The smallest continent in the world can affect sea level worldwide,” said lead author John Fasullo of NCAR. “Its influence is so strong it can temporarily overcome the background trend of rising sea levels that we see with climate change.”

The La Niña event that produced Australia’s big wet also caused heavier rains in South America, but Fasullo observed: “Only in Australia could the atmosphere carry such heavy tropical rains to such a large area, only to have those rains fail to make their way to the ocean.”