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Science News in Brief

By Stephen Luntz

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Water Rat Water Testers
Water rat numbers serve as good indicators of the health of wetlands, so their decline in southern-western Australia is a concern.

“Little is known about the Australian water rat. They are severely under-researched all over Australia, with most research occurring in the 1950s – this just comprised of vague habitat descriptions or animal sightings,” says Ms Clair Smart, who surveyed lakes and wetlands in metropolitan Perth for her Honours thesis at the University of Western Australia.

“A large amount of wetlands on the Swan Coastal Plain have been destroyed and, of those remaining, many are degraded, polluted, contaminated or drying out,” Smart says.

In addition to the effects of water diversion and drought, Smart found that populations of the native mammals are affected by lead pollution but benefit from the greater productivity of iron-rich waters.

Smart is seeking opportunities to translocate water rats to healthier wetlands.

Slow Food for Weight Loss
Speed of eating is a powerful predictor of weight, at least among middle-aged women, according to University of Otago researcher Dr Caroline Horwath.

“For every one-step increase in a five-step scale ranging from ‘very slow’ eating to ‘very fast’, the women’s BMI increased by 2.8%, which is equivalent to a 1.95 kg weight increase in a woman of average BMI for this group,” Horwath says.

Horwath acknowledges that underlying factors that also cause obesity drive rapid eating but says: “If there is a causal link, reduction in eating speed is a very promising way to prevent weight gain”.

The study was conducted on 1500 women aged 40–50 and controlled for age, ethnicity, smoking, physical activity and menopause status. A follow-up study is being undertaken to test if the relationship is causal, and intervention trials will begin if this appears likely.

Diabetes Link to Bowel Cancer
Men with Type 2 diabetes have double the risk of developing bowel cancer of other men their age. One in 12 Australians will be diagnosed with the disease before the age of 85.

“On the strength of these results, doctors should consider lowering the screening threshold for these patients,” said Prof Tim Davis of the University of Western Australia’s School of Medicine and Pharmacology.

Davis conducted an 11-year study of 1300 people with Type 2 diabetes and noted: “When detected early, 90% of bowel cancer cases can be treated successfully. Unfortunately the condition is often not diagnosed until it reaches an advanced stage and is now Australia’s second leading cancer killer.”

Both diabetes and bowel cancer are on the rise. Bowel cancer has also recently been linked to desk jobs, probably through excessive sitting (AS, July/August 2011, p.11).

Lord Howe Species Threatened
Lord Howe Island makes a major contribution to NSW’s marine biodiversity, but this is under threat without protection of critical habitat, a study by Southern Cross University has found.

“We studied the habitats of seven fish species that are threatened or vulnerable to extinction in northern NSW, covering rocky subtidal reefs and carbonate (coral) reefs of Lord Howe Island and surrounding islands,” said Dr Steve Purcell. Some were found in healthy numbers around Lord Howe, but Purcell noted: “We searched for 13 hours in seagrass beds for endemic seahorses and pipefishes and found only one”.

The research produced new understanding of the ecological conditions on which some species depend. “Our study shows that double-header wrasses have a closer association with seagrass than previously understood,” Purcell said.

Iron Rice
Processes to transport iron to edible parts of the rice plant have been engineered into the cereal, producing an accompanying increase in zinc.

“Rice is the primary source of food for roughly half of the world’s population, particularly in developing countries, yet the polished grain, also known as white rice, contains insufficient concentrations of iron, zinc and pro-vitamin A to meet daily nutritional requirements,” said Dr Alex Johnson of the Australian Centre for Plant Functional Genomics (ACPFG).

The ACPFG’s rice has four times the iron of conventional rice, making it the first rice variety reported capable of giving the recommended daily intake of iron. The World Health Organisation considers iron deficiency the world’s most common nutritional disorder. “A lack of genetic variation in rice has hindered efforts by conventional breeding programs to address iron levels,” Johnson said.

The production of the high iron and zinc rice under greenhouse conditions was published in PloS ONE.

Incontinence Widespread
Urinary incontinence (UI) is far more widespread among young women than has previously been realised. The problem has not been tackled as a result of this underestimation of its frequency.

Tessa O’Halloran, an Honours student at Monash University’s Department of Medicine, interviewed 1000 healthy younger women. “Our research found that UI affects 12.6% of women under 30 years, unrelated to pregnancy, and is associated with impaired well-being,” O’Halloran said.

The assumption has existed that UI is restricted to older women and those who are, or have been, pregnant. O’Halloran found that while UI is more common among women who have been sexually active, it is 50% less common while taking oral contraceptives.

“I encourage young women who are experiencing this problem to speak to a medical practitioner to learn how to best manage the problem in the short-term and then to prevent a worsening of the condition in later life,” O’Halloran said.

Thermopower for Nanobots
A step has been taken towards the goal of providing an energy source for nanomachines. “The development of miniaturised energy sources is a key challenge to overcome in order to build the next generation of electronic devices,” says Mr Sumeet Walia, a PhD student at RMIT University’s Microplatforms Research Group. Walia noted that as electronic devices have become smaller, power sources have not been able to keep pace.

Walia has published developments in new semiconductor structures suited to the task in Energy and Environmental Science. “We focus on thermopower waves – which generate intense waves of electrical current by sweeping electrical carriers from one end of materials to another – because of their potential for creating small-scale power sources that can release energy at very high rates,” he said.

Walia’s supervisor, A/Prof Kourosh Kalantar-Zadeh said: “Tiny electronic devices powered by thermopower waves could apply large energies to targeted cancer cells inside the human body, enabling an exceptional level of precision in cancer treatment”.

Swamp Bush-Pea Blooming
The horrors of the 2009 Victorian bushfires have at least given indigenous plants an advantage over introduced species. Dr Arn Tolsma of the Arthur Rylah Institute has found that the threatened swamp bush-pea (Pultenaea weindorferi) may have benefited most of all.

The bush-pea normally grows sparsely in drainage lines around Kinglake but Tolsma says: “It is possible that we have gone from a total population of a few thousand plants before the fires to millions at the moment. A lot of native plants have hard seeds that are stimulated to germinate by the heat or smoke produced by bushfires, and the swamp bush-pea seems to be a champion of this response.”

The burst of life will leave plenty of seeds in the ground waiting for the next fire. However, Tolsma says the swamp bush-pea will not cease to be threatened if, as expected, other plants displace it in the next few years.

Biology Becomes Clear
An aqueous reagent known as Scale turns biological tissue transparent, transforming our capacity to see deep into samples.

In work published in Nature Neuroscience, researchers at the Japanese research institute RIKEN revealed that Scale is able to perform this clearing trick far more effectively than other reagents, and does so without damaging the sample in other ways. They have combined this with techniques that maintain the intensity of light from fluorescent proteins encoded in the tissue to be able to study neurons in the mouse brain at unprecedented depths.

“Our current experiments are focused on the mouse brain, but applications are neither limited to mice nor to the brain,” Atsushi Miyawaki explains. “We envision using Scale on other organs such as the heart, muscles and kidneys, and on tissues from primate and human biopsy samples.”