Parasites control their hosts using stolen genes
Horsehair worms come straight out of a horror movie. Born in water, they use aquatic insects to hitchhike to dry land where they’re eaten by unsuspecting insects like crickets or mantises. Once inside the host’s body the parasite starts growing and manipulating its host’s behaviour – ultimately forcing it to jump to its death in a body of water. Then, the worm bursts out to reproduce.
Previous research has suggested that horsehair worms hijack their hosts’ biological pathways and increase movement towards light, which causes them to approach water. It’s been thought that they produce molecules that mimic those in the host’s central nervous system, but how they do this has remained a mystery until now.
A new study in Current Biology has found that Chordodes horsehair worms likely acquired the genes to manipulate their hosts from the hosts themselves.
“Strikingly, many of the horsehair worm genes that could play important roles in manipulating their hosts were very similar to mantid genes, suggesting that they were acquired through horizontal gene transfer,” says Tappei Mishina at the RIKEN Center for Biosystems Dynamics Research (BDR), Japan.
Horizontal gene transfer is a process in which genes are transferred from one organism to another, but not through reproduction. The researchers found more than 1,400 Chordodes horsehair worm genes that match those in mantises – the ones associated with neuromodulation, attraction to light, and circadian rhythms appear to play a role in host manipulation.
Making ceramics tougher to crack
Ceramics are able to withstand extremely high temperatures and resist corrosion and surface wear, all while remaining lightweight. These properties make them useful for use in aerospace components and protective coatings, but their brittleness means they break easily under stress.
The new study looks at a class of ceramics known as high-entropy carbides – materials containing carbon atoms bonded with multiple metal elements. The researchers found that the key to enhancing ceramic toughness is to use metals from the fifth and sixth columns of the periodic table because they have a higher number of valence electrons.
Valence electrons reside in an atom’s outermost shell of electrons and are the ones that engage in bonding with other atoms.
“Those extra electrons are important because they effectively make the ceramic material more ductile, meaning it can undergo more deformation before breaking, similar to a metal,” says Kenneth Vecchio, professor of nanoengineering at the University of California San Diego, who led the study.
The challenge now is to scale up the production of these tough ceramics for commercial applications.
Robotic prosthetic ankles improve stability
Researchers have found that robotic prosthetic ankles that are controlled by nerve impulses allow amputees to move more naturally and improve their stability.
Their findings are outlined in a paper in Science Robotics.
“This work focused on ‘postural control,’ which is surprisingly complicated,” says Helen Huang, corresponding author of the study and Professor in the Joint Department of Biomedical Engineering at North Carolina State University.
“Basically, when we are standing still, our bodies are constantly making adjustments in order to keep us stable. For example, if someone bumps into us when we are standing in line, our legs make a wide range of movements that we are not even necessarily aware of in order to keep us upright.
“We work with people who have lower limb amputations, and they tell us that achieving this sort of stability with prosthetic devices is a significant challenge. And this study demonstrates that robotic prosthetic ankles which are controlled using electromyographic (EMG) signals are exceptionally good at allowing users to achieve this natural stability.”
EMG signals are the electrical signals from an individual’s muscles. The team worked with 5 people who had amputations below the knee on one leg, fitting them with a prototype robotic prosthetic ankle that responds to EMG signals that are picked up by sensors on the leg.
Participants were significantly more stable when using the prototype, being less likely to stumble or fall. They are now conducting a larger trial to both demonstrate the effects of the technology and identify which individuals may benefit most.
How to reduce injury risk of e-scooters
As the use of e-scooters has increased significantly in recent years, so too has the number of accidents involving this relatively new form of transport. Knowledge about the injury mechanisms in e-scooter accidents is limited, but a new study has addressed this gap to make recommendations to injury risk.
The research team analysed accidents in the literature, accident records, and videos, along with Human Body Model simulations, to predict injuries in e-scooter accidents.
They found that wearing a helmet while riding an e-scooter can reduce the risk of head injuries by 44%.
The simulations also showed that collisions with pedestrians often result in serious injuries, which a ban on e-scooters on pavements and footpaths would mitigate. Risk of head injury to pedestrians is also reduced by 49% when collision speed is reduced from 25 km/h to 15 km/h.
“In general, the risks of this form of mobility seem to be underestimated, which is why an increasing number of injuries is expected in the coming years,” says Christoph Leo from the Vehicle Safety Institute at Graz University of Technology, Austria, project manager of the research.
“You are safer in road traffic on foot or by bike and simultaneously do something good for yourself and the environment. Anyone who really needs to ride an e-scooter, please at least put on a helmet.”
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