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Physicists use atomic magnetometers to measure the biomagnetic signals of the carnivorous plant

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Physicists use atomic magnetometers to measure the biomagnetic signals of the carnivorous plant

The Venus flytrap (Dionaea muscipula) is a carnivorous plant that encloses its prey using modified leaves as a trap. During this process, electrical signals known as action potentials trigger the closure of the leaf lobes. An interdisciplinary team of scientists has now shown that these electrical signals generate measurable magnetic fields. Using atomic magnetometers, it proved possible to record this biomagnetism.

“You could say the investigation is a little like performing an MRI scan in humans,” said physicist Anne Fabricant. “The problem is that the magnetic signals in plants are very weak, which explains why it was extremely difficult to measure them with the help of older technologies.”

Electrical activity in the Venus flytrap is associated with magnetic signals

We know that in the human brain voltage changes in certain regions result from concerted electrical activity that travels through nerve cells in the form of action potentials. Techniques such as electroencephalography (EEG), magnetoencephalography (MEG), and magnetic resonance imaging (MRI) can be used to record these activities and noninvasively diagnose disorders. When plants are stimulated, they also generate electrical signals, which can travel through a cellular network analogous to the human and animal nervous system.

An interdisciplinary team of researchers from Johannes Gutenberg University Mainz (JGU), the Helmholtz Institute Mainz (HIM), the Biocenter of Julius-Maximilians-Universität of Würzburg (JMU), and the Physikalisch-Technische Bundesanstalt (PTB) in Berlin, Germany’s national meteorology institute, has now demonstrated that electrical activity in the Venus flytrap is also associated with magnetic signals. “We have been able to demonstrate that action potentials in a multicellular plant system produce measurable magnetic fields, something that had never been confirmed before,” said Anne Fabricant, a doctoral candidate in Professor Dmitry Budker’s research group at JGU and HIM.

The trap of Dionaea muscipula consists of bilobed trapping leaves with sensitive hairs, which, when touched, trigger an action potential that travels through the whole trap. After two successive stimuli, the trap closes and any potential insect prey is locked inside and subsequently digested. Interestingly, the trap is electrically excitable in a variety of ways: in addition to mechanical influences such as touch or injury, osmotic energy, for example salt-water loads, and thermal energy in the form of heat or cold can also trigger action potentials. For their study, the research team used heat stimulation to induce action potentials, thereby eliminating potentially disturbing factors such as mechanical background noise in their magnetic measurements.

Biomagnetism — detection of magnetic signals from living organisms

While biomagnetism has been relatively well-researched in humans and animals, so far very little equivalent research has been done in the plant kingdom, using only superconducting-quantum-interference-device (SQUID) magnetometers, bulky instruments which must be cooled to cryogenic temperatures. For the current experiment, the research team used atomic magnetometers to measure the magnetic signals of the Venus flytrap. The sensor is a glass cell filled with a vapor of alkali atoms, which react to small changes in the local magnetic-field environment. These optically pumped magnetometers are more attractive for biological applications because they do not require cryogenic cooling and can also be miniaturized.

The researchers detected magnetic signals with an amplitude of up to 0.5 picotesla from the Venus flytrap, which is millions of times weaker than the Earth’s magnetic field. “The signal magnitude recorded is similar to what is observed during surface measurements of nerve impulses in animals,” explained Anne Fabricant. The JGU physicists aim to measure even smaller signals from other plant species. In the future, such noninvasive technologies could potentially be used in agriculture for crop-plant diagnostics, by detecting electromagnetic responses to sudden temperature changes, pests, or chemical influences without having to damage the plants using electrodes.

The results of the study have been published in Scientific Reports. The project received financial support from the German Research Foundation (DFG), the Carl Zeiss Foundation, and the German Federal Ministry of Education and Research (BMBF).

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Microscale robot folds into 3D shapes and crawls

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Physicists use atomic magnetometers to measure the biomagnetic signals of the carnivorous plant


Cornell University researchers have created microscale robots less than 1 millimeter in size that are printed as a 2D hexagonal “metasheet” but, with a jolt of electricity, morph into preprogrammed 3D shapes and crawl.

The robot’s versatility is due to a novel design based on kirigami, a cousin of origami, in which slices in the material enable it to fold, expand and locomote.

The team’s paper, “Electronically Configurable Microscopic Metasheet Robots,” published Sept. 11 in Nature Materials. The paper’s co-lead authors are postdoctoral researchers Qingkun Liu and Wei Wang. The project was led by Itai Cohen, professor of physics. His lab has previously produced microrobotic systems that can actuate their limbs, pump water via artificial cilia and walk autonomously.

In a sense, the origins of the kirigami robot were inspired by “living organisms that can change their shape.” Liu said. “But when people make a robot, once it’s fabricated, it might be able to move some limbs but its overall shape is usually static. So we’ve made a metasheet robot. The ‘meta’ stands for metamaterial, meaning that they’re composed of a lot of building blocks that work together to give the material its mechanical behaviors.”

The robot is a hexagonal tiling composed of approximately 100 silicon dioxide panels that are connected through more than 200 actuating hinges, each about 10 nanometers thin. When electrochemically activated via external wires, the hinges form mountain and valley folds and act to splay open and rotate the panels, allowing the robot to change its coverage area and locally expand and contract by up to 40%. Depending which hinges are activated, the robot can adopt various shapes and potentially wrap itself around other objects, and then unfold itself back into a flat sheet.

Cohen’s team is already thinking of the next phase of metasheet technology. They anticipate combining their flexible mechanical structures with electronic controllers to create ultra-responsive “elastronic” materials with properties that would never be possible in nature. Applications could range from reconfigurable micromachines to miniaturized biomedical devices and materials that can respond to impact at nearly the speed of light, rather than the speed of sound.

“Because the electronics on each individual building block can harvest energy from light, you can design a material to respond in programmed ways to various stimuli. When prodded, such materials, instead of deforming, could ‘run’ away, or push back with greater force than they experienced,” Cohen said. “We think that these active metamaterials — these elastronic materials — could form the basis for a new type of intelligent matter governed by physical principles that transcend what is possible in the natural world.”



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Genes with strong impact on menopause timing also link to cancer risk

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Physicists use atomic magnetometers to measure the biomagnetic signals of the carnivorous plant


New research has found four genes with some of the largest known effects on the timing of menopause discovered to date, providing new insight into links between menopause timing and cancer risk.

Genes come in pairs, and when women only have one working copy of the four new genes identified (ETAA1, ZNF518A, PNPLA8, PALB2), they have menopause between two and five-and-a-half years earlier than average.

Published in Nature, the large-scale analysis was funded by the Medical Research Council and Wellcome. The team first looked at variation in data from genetic sequencing of 106,973 post-menopausal female participants in the UK Biobank study. Researchers focussed on rare types of genetic changes which cause a loss of the protein, and investigated their effect on the timing of menopause.

The genetic changes studied are all rare in the population, however their influence on menopause is five times greater than the impact of any previously identified common genetic variant. The strongest effect was found from gene variants in ZNF518A, only found in one in 4,000 women. These variants shortened reproductive lifespan more than most previously identified genes.

Discovering the effect of the genes gives scientists a better understanding of the biological mechanisms underpinning menopause, and links to other diseases.

Study co-lead Professor Anna Murray, of the University of Exeter Medical School, said: “For decades, menopause has been under-researched, yet now this is a rapidly evolving area of science. The timing of menopause has a huge impact on women as they plan their careers and lives, and understanding the genetic changes is of particular interest in terms of potential treatments that could prolong reproductive life in future.”

When unrepaired DNA damage occurs in eggs, they can die. The rate at which eggs are lost determines when women experience menopause. The team’s previous work has shown that many genes that influence the timing of menopause are likely to do this by affecting the genetic integrity of eggs. The same factors affect other cells and tissue types in parallel, and in this new study, the team found that many of the genes linked to menopause timing are also risk factors for cancer. These include changes in the BRCA1 and BRCA2 genes, which result in earlier menopause and also in increased risk of cancer.

This is thought to be the process at play in a fifth new gene linked to menopause timing (SAMHD1). The team discovered that changes in this gene can cause women to go through menopause over a year later than average. The researchers also found for the first time that changes in this gene cause predisposition to various cancers in men and women.

Professor John Perry, co-lead from the MRC Epidemiology Unit at the University of Cambridge added: “Past research suggests the female ovary ages at a faster rate than other organ in the body, and this is a model system for understanding the biology of broader ageing. Our latest research builds on this concept, demonstrating that studying ovarian ageing will not only lead to a better understanding of the biology behind infertility and other reproductive disorders, but will enhance our understanding of fundamental processes that regulate DNA damage and cancer risk in the general population.”

Using data from the 100,000 Genomes project, led by Genomics England and NHS England, the team next found that mothers with a high number of genetic variants that cause earlier menopause tended to have more new changes in the DNA they passed onto their children. The study authors believe this is because the relevant genes are involved in repairing damage to DNA, so this function may be compromised in the ovaries, enabling new genetic changes to occur in the eggs.

Dr Hilary Martin, a study co-lead from the Wellcome Sanger Institute, said: “New changes to the DNA in the egg or sperm are the source of all genetic variation in humans, contributing to differences between individuals in their appearance, behaviours and risk of disease. Until now, we knew very little about what influences these new DNA changes, apart from parental age. This is the first time we’ve seen that existing common variation in DNA influences the rate of these changes.”



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Mirror, mirror, in my tank, who’s the biggest fish of all?

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Physicists use atomic magnetometers to measure the biomagnetic signals of the carnivorous plant


What if that proverbial man in the mirror was a fish? Would it change its ways? According to an Osaka Metropolitan University-led research group, yes, it would.

In what the researchers say in Scientific Reports is the first time for a non-human animal to be demonstrated to possess some mental states (e.g., mental body image, standards, intentions, goals) which are elements of private self-awareness, bluestreak cleaner wrasse (Labroides dimidiatus) checked their body size in a mirror before choosing whether to attack fish that were slightly larger or smaller than themselves.

The team of OMU Graduate School of Science student Taiga Kobayashi, Specially Appointed Professor Masanori Kohda, Professor Satoshi Awata, and Specially Appointed Researcher Shumpei Sogawa, and Professor Redouan Bshary of Switzerland’s University of Neuchâtel, were among the group that last year reported the cleaner wrasse could identify photographs of itself as itself, based on its face through mirror self-recognition.

This time, the cleaner wrasse’s behavior of going to look in the mirror installed in a tank when necessary indicated the possibility that the fish were using the mirror to check their own body size against that of other fish and predict the outcome of fights.

“The results that fish can use the mirror as a tool can help clarify the similarities between human and non-human animal self-awareness and provide important clues to elucidate how self-awareness has evolved,” doctoral candidate Kobayashi declared.

This study was financially supported by JST SPRING (JPMJSP2139 to T.K.), JSPS KAKENHI (23KJ1829 to T.K., 19F19713 and 20K20630 to M.K., 22H02703 to S.A., and 20K20154 to S.S.), Swiss Science Foundation (310030_192673 to R.B.), and an OCU Strategic Research Grant 2018-2019 (to M.K. and S.A.).



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