Australasian Science: Australia's authority on science since 1938

Exclusive news for subscribers

By Stephen Luntz

Subscribe for complete access to all news articles, columns and features each month.

Glucose Absorption Gingered Up

Ginger has been used as a traditional medicine for many diseases, but its application to diabetes has been overlooked. Both animal and cell culture studies suggest it may assist with the uptake of blood glucose into muscle cells.

“Under normal conditions, blood glucose level is strictly maintained within a narrow range, and skeletal muscle is a major site of glucose clearance in the body,” says Prof Basil Roufogalis of the University of Sydney’s Faculty of Pharmacy. However, Type 2 diabetes interferes with glucose uptake, at least partly by reducing the efficiency of the GLUT4 protein, which helps to transport glucose into muscle cells.

While insulin is normally considered responsible for controlling this transportation, Roufogalis has shown that ginger can also play a role. “This assists in the management of high levels of blood sugar that create complications for long-term diabetic patients, and may allow cells to operate independently of insulin,” Roufogalis says.

Keen to discover the ginger chemicals responsible, and the mechanism, Roufogalis conducted chromatographic fractioning on a ginger extract solution, producing seven fractions distinguished by polarity. Two fractions demonstrated a capacity to induce glucose uptake in tissue cultures, with the most effective rich in gingerols – the chemicals distinctive to ginger.

The most recent step in the work, published in Planta Medica, has been to show that exposure to gingerols increases the concentration of GLUT4 on the surface of muscle cells. Roufogalis says it is yet to be established whether the increase in GLUT4 concentration balances the loss of efficiency in transport as a result of diabetes, of if other processes are also going on.

“All we know is that insulin resistance, glucose sensitivity and tolerance all seem to be improved in animal studies with ginger,” Roufogalis says. “How that relates to GLUT4 is still not clear. We need clinical trials to demonstrate usefulness, and we hope to be able to get a greater effect by identifying the chemicals involved.’

Thymus Size Predicts Pre-eclampsia

The unexpected, and still unexplained, relationship between pre-eclampsia and thymus size in foetuses could improve the prospects for women experiencing the most common pregnancy-related disease.

“Pre-eclampsia affects an estimated 5000 to 10,000 women in Australia every year,” says Prof Ralph Nanan of the Sydney Medical School, Nepean. The condition usually occurs in the final trimester of pregnancy, triggering high blood pressure, kidney and liver damage. While there are usually no warning signs, maternal obesity and first pregnancy are considered risk factors.

In the Journal of Reproductive Immunology Nanan revealed that babies born to women who suffered pre-eclampsia during pregnancy have smaller thymuses. The thymus plays a crucial role in the immune system by eliminating T-cells that attack the body’s own proteins, and Nanan suspects that children with smaller thymuses will have compromised immune systems. However, he says research to validate this is still underway.

In the process of this discovery Nanan found something even more significant. The reduced size of the thymus was observed on ultrasounds taken on 50 women who experienced pre-eclampsia during pregnancy, compared with 100 controls, and the difference could be seen even before maternal symptoms of pre-eclampsia could be detected.

“We measured a range of other factors in the foetuses and none of them showed significant differences, but the thymus size was easily statistically significant,” Nanan says. He is now conducting a study on 1200 pregnant women, of whom 3–5% are expected to get pre-eclampsia based on typical distributions.

“If our results are confirmed, the next step would be to combine this test with other risk factors to develop a composite tool for more exact predictions,” Nanan says. This could prompt increased monitoring in the most likely cases, and make it far easier to test potential therapies.

Nanan concedes that the cause of the observations remains a mystery. “We know pre-eclampsia occurs when the immune system rejects the foetus, but we don’t know why it reduces thymus size weeks before we see anything else.” The fact that the affected organ is essential to the immune system is unlikely to be a coincidence.

Squid Subdued after Sex

A study of dumpling squid has revealed that they pay a price for sex, but it isn’t a deterrent according to research published in Biology Letters.

Recent research has looked at the cost of sex in terms of energy expenditure and vulnerability to predators (AS, April 2012, p.6). Ms Amanda Franklin of the University of Melbourne’s Department of Zoology observed the small cephalopod known as dumpling squid (Euprymna tasmanica) during and after mating.

“We found that, after mating, both male and female dumpling squid took up to 30 minutes to recover to their previous swimming ability,” Franklin says. “This suggested that the squid were suffering from temporary muscle fatigue. Our results were a little surprising as the degree of fatigue was similar in both genders even though mating looks more strenuous for males.”

While squid were unable to forage or flee predators in this post-coital state, the danger was small compared with the mating itself. Not only do the squid mate while hovering above the sand, but mating can take 1–3 hours. During this time the male holds the female from underneath and releases spermataphores, or sperm-containing bundles, which he progressively inserts inside her.

Given their precarious positions, the squid try to disguise their location by changing colour and producing clouds of ink.

Despite the danger, dumpling squid mate often during their year-long lifespan. Franklin is currently studying whether the number of times a female squid mates affects her longevity, as well as whether the presence of a predator inhibits mating.

Canadian Origin for Australia’s Metals

Some of Australia’s richest mineral deposits may be the result of an association with Laurentia, which now forms the bulk of North America, according to researchers from Geoscience Australia. The relationship with the Canadian component of Laurentia was a far more profitable marriage than a later dalliance with southern portions of the same continent.

Between 1800 and 1500 million years ago most of the Earth’s land masses combined in the supercontinent of Nuna (also known as Columbia). “When continents amalgamate you have a lot of subduction zones as you have to eliminate the oceanic crust between. Volcanoes form above the zones and deposits form inside these,” says Dr David Houston. “Behind the volcanic zone you get another class of deposits where heat from magma dissolves metals from rocks, rises to the sea floor and deposits them there.”

Supercontinental break-ups can also leave a legacy. “Rift valleys form when the crust is pulled apart. Heat comes in and drives the circulation of hydrothermal fluids. You get a different suite of deposits from this, such as lead–zinc deposits,” Houston says.

Houston says their ages indicate that the minerals at Broken Hill and Mt Isa originated during the Nuna break-up, with a number of major copper and gold deposits arising from its earlier formation.

Dr Alex Lambeck says that a distinct isotopic trace to rocks around these deposits mark them as unAustralian. The isotopes are consistent with a major volcanic province existing in a neighbouring continent, with a huge river bringing sediment to Australia.

Lambeck set about finding the presence of similar isotopes from the same era on another continent, indicating it was Australia’s neighbour at the time. Laurentia provided the most promising source, although Baltica (made up of Scandinavia and parts of eastern Europe) remains a possible alternative.

Several proposals exist for how Australia and Laurentia might have fitted together at the time, but Houston says his team favour the idea that northern Australia was nudging the Yukon territories.

Hundreds of millions of years after Nuna broke up, Australia and Laurentia had another close encounter as part of the supercontinent Rodinia. This time, Houston says, we were parked next to the Californian or Mexican end, and the separation was less profitable, although some uranium deposits and smaller mines resulted.

Ancient Penguins Leave Mossy Legacy

Pockets of lush moss in Antarctica are a result of ancient penguin colonies and the nutrients they left behind in their droppings.

Even ice-free parts of Antarctica are usually devoid of nutrients, having been stripped by wind and past glaciations. However, in a presentation to the Society of Experimental Biology’s annual meeting, Prof Sharon Robinson of the University of Wollongong demonstrated a characteristic “seabird signature” in soil nitrogen at the sites.

“As nitrogen moves through an ecosystem, the N15 is enriched,” Robinson says. “Nitrogen that has gone from plankton to krill to fish to birds has a distinct signature.”

Robinson checked the moss and confirmed that the nitrogen was coming from the soil rather than from wind-borne ammonia derived from surviving penguin colonies.

Since the last ice age, Antarctica’s edges have experienced isostatic rebound, rising out of the ocean now that they are carrying less weight. Locations popular with penguins 3000–8000 years ago are marked by the presence of eggshells, bones and the pebbles that Adelie penguins use to build their nests. However, they are now too far from the sea to make attractive nesting grounds.

Ice has been retreating at these sites for thousands of years, but Robinson says some of the sites near Casey Station are seeing moss overtaken by lichen. “At three out of four of the sites we are studying it is getting drier,” she says. “This is partly because wind speeds around the edge of the continent have increased as a result of the ozone hole, but snow banks that used to melt in summer have been reduced in the last two or three decades as a result of global warming.”

Robinson says it is not known how the moss reached the sites. While it was once thought to have been blown from other lands or been brought by sea birds she speculates: “Tiny invertebrates in the soil have been shown to have survived the ice age, so it is possible the moss spores have been there for many thousands of years.

Robinsons describes this as “a reminder to scientists and tourists we need to make sure our clothes and boots are as clean as possible to avoid bringing something in”.

Warming Leaves Are Narrowing

The leaves of the narrow-leaf hopbush (Dodonaea viscosa) have become dramatically narrower in recent decades, apparently in response to rising temperatures.

Hot, dry climates favour narrow leaves, providing a way to lose heat without too much loss of water. Studies have shown that individuals within the same species of plant growing in drier environments will have narrower leaves.

The narrow-leaf hopbush had leaves averaging just 4–5 mm in the 19th century. However, Dr Greg Guerin of the University of Adelaide’s School of Earth and Environmental Sciences says there was considerable variation around this average, with ranges from 2–9 mm.

The plant is widespread through the Flinders Ranges, and was extensively collected in biological surveys, revealing that the hottest environments hosted the narrowest leaves.

Guerin used 250 collections to make a comparison of the hopbush’s leaves since the 1880s, noting that South Australian temperatures have increased by 1.2°C since 1950 while rainfall in the Flinders Ranges has not changed. In Biology Letters he has revealed that the leaves have narrowed by 2 mm over that time, a roughly 40% reduction.

“Climate change is often discussed in terms of future impacts, but changes in temperature over recent decades have already been ecologically significant,” Guerin says. “It’s important to understand how plants cope with changing climates, because species that are more adaptive to change may be good candidates for environmental restoration efforts.

“Other species in the region have less potential to adapt. These species may rely more heavily on migration – moving from location to location where the climate is favourable – but this can be problematic in a landscape fragmented by human activity.”

Guerin says he is thinking of conducting garden experiments where individual plants with different parentage are grown alongside each other as a way of establishing whether the process is one of natural selection or reveals flexibility in the responses of individual plants. “I tend to suspect some component of both,” he says.

While the width of the narrowest leaves has barely changed, wider-leaved specimens have largely disappeared.

The hopbush remains widespread in the Flinders Ranges, but Guerin says it is not clear if its abundance has changed with time.

Sea-Ice Warming Link Explained

The Arctic has been warming much faster than the planet as a whole. Prof Ian Simmonds of the University of Melbourne’s School of Earth Sciences says the rise can be anything from double to four times the global rate depending on whether you define the Arctic as the ocean only or include some surrounding lands.

This is not completely surprising since carbon dioxide traps radiating heat best at low temperatures. However, Simmonds notes: “Most of the heat is not trapped directly by carbon dioxide. The CO2 warms the air a little, enabling it to hold more water vapour, which then in turn traps more heat.

“However, the Arctic air is so cold that even with a little warming it holds very little water vapour.” Consequently, the warming effects are not straightforward to predict.

Two years ago the University of Melbourne team revealed the role that loss of sea-ice was playing by allowing more heat to be absorbed by the darker waters of the oceans (AS, July/August 2010, p.10). Now in Geophysical Research Letters the same researchers have examined how the removal of this ice blanket affects the interaction between the ocean and the atmosphere.

“Loss of sea-ice contributes to ground level warming while global warming intensifies atmospheric circulation and contributes to increased temperatures higher in the Arctic atmosphere,” Simmonds says.

He adds that one of the features of a warmer world is increased circulation between the tropics and the poles. “This circulation transports energy to the Arctic region, increasing temperatures further up in the atmosphere.

“There is a complex signal in the vertical structure of the warming,” Simmonds explains. “We used that to work backwards to try to understand what is going on. We’ve shown that the surface warming comes from the loss of sea-ice, but above a couple of kilometres is the increased transport of warm air from lower latitudes.

“With Arctic sea-ice set to break the record for lowest coverage this year we are in for interesting times.”

Smallest Electric Fields Revealed

Monash University scientists have demonstrated a capacity to measure the shape of electron fields within atoms, offering the potential for improved design of solid-state technologies such as computer chips and solar cells.

“We understand very well the electric field within a single atom,” says Dr Scott Findlay of the School of Physics. “However, inside a material the field is affected by surrounding atoms and the long range constant field that can exist within polarised objects.”

Findlay has combined with Japanese researchers to reveal these fields using scanning transmission electron microscopes and highly sensitive detectors. “It’s like rolling marbles to look for slight slopes in the ground,” Findlay says. “If the marble deflects to the left, that must be downhill; if the beam of electrons deflects to the left, that must be the direction the field points.”

Electron microscopes have allowed us to see the world at the atomic scale, but Findlay says this has generally been done with rotationally symmetric detectors to correct for aberrations. “Directional detectors have been used for mapping magnetic fields, but putting the two ideas together in this way is new.”

Alternative techniques, such as scale electron holography, also exist for mapping electron fields at such minute scales, but Findlay says these require great stability. “We’re seeing things that we’ve never seen before. Understanding the behaviour of materials and their electric fields on a very small scale expands what we are able to do with them,” Findlay says.

Supplements Quell Quake Stress

Two New Zealand studies have emphasised the benefits of micronutrient supplements.

A/Prof Julia Rucklidge of the University of Canterbury’s Department of Psychology was studying the effects of vitamin and mineral pills when an earthquake struck Christchurch in September 2010. People taking the supplements coped better than their peers.

When a more devastating quake hit in February 2011 Rucklidge investigated further. Operating from makeshift offices she gave 91 participants either a single Berocca or four or eight CNE pills. Berocca is primarily a B group vitamin pill, while CNE contains a wider range of minerals. Twenty-five people served as a non-randomised control.

“The most important thing is that all three treatment groups improved during the study whereas the control group did not. You don’t cure everyone in each group but, overall, participants were significantly better in terms of stress levels, depression, anxiety and post-traumatic stress disorder,” Rucklidge says.

“Both groups on CNE had less traumatic thoughts about the earthquake than the Berocca group, and the group taking CNE8 were more likely to feel very much improved’ compared with Berocca.”

Further earthquakes sustained the anxiety of the control group, making the lower stress responses of those on the supplements an encouraging sign.

While acknowledging that eight pills a day might create a significant placebo effect, Rucklidge notes that Berocca has outperformed placebos in double-blind trials. “We are comparing not with a placebo, but with something we already know works,” she says.

The disruption produced by a third earthquake prevented Rucklidge from enrolling a larger sample but the results “seem to suggest the additional minerals in CNE are performing a role, along with the B group vitamins,” she says.

“After a disaster we tend to look at issues like water and sanitation but we don’t think of nutritional needs, although we know survivors are more likely to eat processed foods,” says Rucklidge, whose results were published in Human Psychopharmacology.

Dr Susan Jack of Otago University has separately demonstrated the anaemia-fighting potential of micronutrient powders. She provided the mothers of 3112 6-month-old infants with powders containing iron and 14 vitamins and minerals. In the Archives of Pediatrics & Adolescent Medicine she demonstrated a 20% reduction in anaemia.

“This study provides clear evidence supporting the roll-out of ‘Sprinkles’ as a micronutrient intervention in Cambodia and similar settings,” Jack says. Satchels of Sprinkles cost 2–3¢ per child, or $16 over an 18-month period.

Floating Stones Observed off NZ

Vast fields of floating lumps of pumice the size of golf balls have been found off New Zealand. While the idea of floating rocks covering an area the size of Belgium may arouse apocalyptic visions, vulcanologist Mr Brad Scott from GNS Science says events such as this happen around once per year worldwide, although usually on a smaller scale.

Pumice is a volcanic rock riddled with holes that can reduce its average density below that of water, allowing it to float. When emitted by undersea volcanoes it rises to the surface.

Although the initial chunks may vary in size Scott says: “Pumice is very fragile. It gets broken easily, so I would be surprised if anything larger than a few centimetres across would survive long in the ocean environment without being smashed up.”

Although the stones have been sighted over an area of 30,000 km2, their density is quite low.

Scott was reluctant to speculate on the total volume of rocks, but patches are dense enough to be visible from satellites.

“Colleagues in French Polynesia have been tracking back through satellite images until we can’t find signs of them anymore,” says Scott. “It seems the first images were around 17–19 July. There was earthquake activity in the area on those dates, and we think that accompanied some eruptions.”

The source would have been an unknown volcano. New Zealand has been experiencing a surge of volcanic activity, with four volcanoes erupting at once on or near the islands. However, Scott says: “Hard as it is to believe, this is probably a coincidence”.

Scott warns that stones could clog the intakes of ships as they suck in water for cooling, but says any impact on marine life would probably be restricted to the area immediately around the undersea vent. If the stones do not wash ashore they become waterlogged and eventually sink.

Vitamin D Reduces Multiple Sclerosis Symptoms

A connection has emerged between the most common treatment for multiple sclerosis (MS) and vitamin D. While the finding may eventually lead to better treatment for the disease, the scientists involved say we have yet to discover what it really means.

Vitamin D can reduce inflammatory pathways in the immune system, and previous work has found that MS patients with high vitamin D levels have fewer and less severe attacks than those who are vitamin D-deficient.

Dr Steve Simpson of the Menzies Research Institute Tasmania analysed data from 178 patients with MS in southern Tasmania, where limited sunlight is considered a likely explanation for high rates of MS. Many of these patients were using interferon-beta, a treatment given to 60% of people with relapsing-remitting MS.

“Not only did we find that persons taking interferon-beta had higher vitamin D levels than those not taking it, we also found that this increase in vitamin D was due to an enhancement of the association between sun and vitamin D, with persons on interferon-beta having nearly three times as much vitamin D from similar amounts of sun exposure to those not taking interferon-beta,” Simpson says.

“In this analysis, however, we found that vitamin D was only associated with reduced risk of relapse among those using interferon-beta,” Simpson says. “Interestingly, the reciprocal was also true, with interferon-beta only associated with reduced risk of relapse among those with higher levels of vitamin D.”

The findings, published in Neurology, are particularly interesting because Simpson says no one knows why interferon-beta works. “MS is an immunological disorder, so it was thought immunological parameters might be therapeutic or harmful. It was found that interferon-gamma is harmful and beta is beneficial.”

However, the drug does not work in about 20% of cases, and in a similar number the side-effects outweigh the benefits.

Simpson notes that clinical trials will be needed to see if vitamin D doses can be combined with interferon-beta for maximum benefit. A number of explanations seem possible. “MS may interfere with vitamin D production or something downstream, and interferon may somehow correct this.” Alternatively vitamin D may be necessary to allow interferon-beta to perform some other role.

Simpson says if sunlight exposure is too low interferon-beta may “have nothing to correct”, and that it is possible “the reason people not on interferon-beta don’t show the association between vitamin D levels and better outcomes is that the levels are so low it doesn’t generate an effect”. The last idea raises the possibility that massive doses of vitamin D may perform a role even without interferon.