Brainless slime moulds can remember

UNIVERSITY OF SYDNEY

Share on print The discovery of this chemical memory system that helps slime mould remember where they've been could help explain how the memory of multi-cellular organisms may have evolved. Image: Tanya Latty Can you have a memory if you don't have a brain? The question has been answered with the discovery that brainless slime moulds use excreted chemicals as a memory system. The finding by University of Sydney researchers is strong support for the theory that the first step toward the evolution of memory was the use of feedback from chemicals. "We have shown for the first time that a single-celled organism with no brain uses an external spatial memory to navigate through a complex environment," said Christopher Reid from the University's School of Biological Sciences. The research, led by Reid, with colleagues from the school and a colleague from Toulouse University, is published in the Proceedings of the National Academy of Sciences journal today. "Our discovery is evidence of how the memory of multi-cellular organisms may have evolved - by using external chemical trails in the environment before the development of internal memory systems," said Reid. "Results from insect studies, for example ants leaving pheromone trails, have already challenged the assumption that navigation requires learning or a sophisticated spatial awareness. We've now gone one better and shown that even an organism without a nervous system can navigate a complex environment, with the help of externalised memory." The research method was inspired by robots designed to respond only to feedback from their immediate environment to navigate obstacles and avoid becoming trapped. This 'reactive navigation' method allows robots to navigate without a programmed map or the ability to build one and slime moulds use the same process. The researchers used a classic test of independent navigational ability, commonly used in robotics, requiring the slime mould to navigate its way out of a U-shaped barrier. As the slime mould (Physarum polycephalum) moves it leaves behind a thick mat of non-living, translucent, extracellular slime. When it is foraging the slime mould avoids areas that it has already 'slimed' suggesting it can sense extracellular slime upon contact and will recognise and avoid areas it has already explored. "This shows it is using a form of external spatial memory to more efficiently explore its environment," said Reid. "We then upped the ante for the slime moulds by challenging them with the U-shaped trap problem to test their navigational ability in a more complex situation than foraging. We found that, as we had predicted, its success was greatly dependent on being able to apply its external spatial memory to navigate its way out of the trap." In simple environments the use of externalised spatial memory is not necessary for effective navigation but in more complex situations it significantly enhances the organism's chance of success, just as it does for robots using reactive navigation. Christopher Reid's work also appears in the Macleay Museum's current exhibition The Meaning of Life which features prominent research from the School of Biological Sciences in its 50-year history. Editor's Note: Original news release can be found here.

Skin cancer cream a step closer

RMIT

Share on print Melanoma is responsible for 75% of skin cancer deaths in Australia and currently the only treatment is to remove the tumour. The new peptide is toxic to melanoma cells but leaves normal skin cells unharmed. Image: jamesbenet/iStockphoto RMIT University researchers have designed a peptide that imitates a melanoma-killing virus, in a biomedical engineering advance that could lead to the development of a cream to target and treat Australia's "national cancer". The RMIT team has successfully synthesised a peptide that mimics the activity of a virus protein, with laboratory tests showing the peptide kills melanoma cells while leaving normal human skin cells unharmed. Lead investigator Dr Taghrid Istivan said peptide therapy had the potential to lead to new, non-invasive treatments for melanoma, which is responsible for 75 per cent of skin cancer deaths in Australia. "Australia has the highest incidence of melanoma in the world, with more than 11,000 new diagnoses each year," Dr Istivan said. "Currently the only effective treatment for early stage melanoma is surgery to cut out the tumour and healthy skin surrounding the affected mole. "The peptide we have developed is toxic to melanoma cells but leaves normal skin cells unaffected. "With further work, including clinical trials, we hope our research could lead to the development of a cream to painlessly and efficiently treat early stage melanoma." Dr Istivan and her colleagues in RMIT's Health Innovations Research Institute and the School of Applied Sciences tested the efficacy of a peptide - a short chain of amino acids - that was designed to work like the proteins of the myxoma virus, a cancer-killing virus shown to be toxic to melanoma in previous studies. "A virus protein is big, expensive to synthesise and has inherent risks when used in medical treatments, because all viruses can mutate," she said. "By synthesising a small peptide that mimics the action of a protein, we can offer a stable, safe, targeted and cost-effective alternative." The researchers used a novel bioengineering method developed at RMIT by Professor Irena Cosic and Dr Elena Pirogova, from the School of Electrical and Computer Engineering, to design the peptide. The peptide was synthesised as a powder, liquefied and tested in vitro on normal human cells and melanoma cells. Dr Istivan is presenting the research findings at the 40th Congress of the International Society of Oncology and Biomarkers (13 - 17 October, Jerusalem). Editor's Note: Original news release can be found here.

The best new superfood

CHARLES STURT UNIVERSITY

Share on print Anti-cancer properties have been found in extracts from Australian-grown faba beans, along with effects that may have implications for treating hypertension and maintaining healthy weight. As part of a study into the health benefits of faba beans, PhD student from Charles Sturt University (CSU), Ms Siem Siah applied phenolic compounds from Nura and Rossa faba beans to five different cancer cell lines in laboratory experiments at Wagga Wagga. In all cases the rate of cancer cell death was accelerated. Ms Siah said, “We know that antioxidant properties are potentially linked to anti-cancer properties, so we were trying to look for the connections.” Ms Siah’s PhD principal supervisor Dr Chris Blanchard from CSU’s School of Biomedical Sciences said the research team, from CSU, NSW Department of Primary Industries (DPI) and CSIRO, was astonished by the findings from experiments on anti-cancer and enzyme-inhibiting properties. “We were absolutely blown away by the results,” Dr Blanchard said.  The findings have been published in the British Journal of Nutrition. NSW DPI chemist Dr Jennifer Wood co-supervised Ms Siah’s PhD with Dr Blanchard. Dr Izabela Konczak from CSIRO Food and Sciences oversaw the experiments. The preliminary experiments on antioxidant properties were carried out at CSU and the cell culture assays were carried out at CSIRO. In plants, phenolic compounds are chemicals largely responsible for colour, metabolism and defensive mechanisms. Because they play a strong protective role against insects, they are often found in seed coats and hulls. Ms Siah grew cultures of four cancer cell lines – bladder, stomach, liver and colon cancers – in flasks, then applied the phenolic compounds to them directly and waited 24 hours to measure the proliferation of cells. The rate of cancer cell multiplication was greatly reduced once the faba bean extracts were applied. For a fifth type of cancer cell, acute promyelocytic leukemia, Ms Siah applied a method called flow cytometry. Dr Wood said the experiment yielded an insight into the mechanism that inhibited the cancer cell multiplication. “Normal healthy cells are programmed to multiply, grow and die (cell death is called apoptosis),” Dr Wood said. “Cancer cells evade the process of apoptosis, continue to proliferate and become tumours. “This work showed faba bean phenolics induced normal cell death in the cancer cells. Conversely, the extracts had no effect on the proliferation of normal human colon cells tested, a very favourable outcome.” Additional experiments on the interaction with important human enzymes showed that phenolic extracts from faba beans inhibited angiotensin converting enzyme (ACE), a common target of pharmaceutical medication for hypertension. These compounds also inhibited the action of the digestive enzymes alpha-glucosidase and lipase, which could mean slower digestion (and therefore a longer feeling of satiety), and lower sugar and fat absorption by the digestive system.                                  Dr Blanchard said several avenues could be pursued to build on these findings and look for therapeutic human health applications, if funding becomes available. “One is to generate large amounts of these extracts and undertake feeding trials to see if we can directly use extracts as a natural product to improve health outcomes. “Or you could drill down further and find out what compounds are involved in these activities, synthesise them and have them approved for pharmaceutical use. “Or we could do further testing in human trials, incorporating faba beans in diets to demonstrate exactly what happens when we consume them over a long period,” Dr Blanchard said.  Dr Blanchard and Ms Siah are members of the EH Graham Centre for Agricultural Innovation - a collaborative research alliance of CSU and NSW DPI. Editor's Note: Original news release can be found here.