The week’s most astounding developments from the neobiological frontier.

April 14, 2022

Gut bacteria and the brain: Who rescues whom?

Researchers at the Pasteur Institute in Paris have demonstrated that NOD2 protein receptors found on neurons in the mouse brain can directly sense tiny pieces of cell wall broken off by bacteria in the gut. In direct response to sensing those molecules, the mouse regulates physiological processes like hunger and body temperature through its hypothalamus, a brain region which is also involved in regulating sleep cycles and fight-or-flight responses. This sensing likely takes place in other mammalian brains as well, including humans, and besides providing a better understanding of gut/brain cross-talk and potential ways to modulate things like appetite and body temperature, the work presents a delicious evolutionary puzzle: Why? Has the mammalian brain evolved to sense danger through bacteria in the gut so it can shut down appetite and avoid becoming sick—or has our bacterial microbiome evolved to manipulate our brains, regulate our food intake, and protect their own backyard? Science

Dutch study shows nurture dominates nature in microbiome

And speaking of gut bacteria, a major new study came out this week from the Dutch Microbiome Project looking at the gut microbiomes of 8,208 people aged 8–84 from three generations across 2,756 families. Led by researchers at the University of Groningen, the study asked how the human gut microbiome is shaped by genetics, lifestyle, medication, socioeconomic status, environmental exposures, and diet, and it found the primary drivers are where we live and who we live with. Only 6.6 percent of microbial species found in the gut are heritable whereas 48.6 percent of them can be explained by cohabitation. Nature

A soft robotic gel that can break bricks

Researchers at Seoul National University in South Korea have designed a fast hydrogel-based actuator—a breakthrough in soft robotics that could lead to better ways of designing implantable robots for surgical purposes. Inspired by the ability of plants to break through cracks in the concrete, the researchers exploited the phenomenon of turgor pressure, the loss of which makes strong and crisp plant leaves wilt when they lose moisture. Combining that principle with electroosmosis, they designed a soft hydrogel that is strong enough to break through a brick. Science

Edible silk barcodes could help combat fake drugs

Researchers at the National Institute of Agricultural Sciences in Wanju, South Korea, and Purdue University in West Lafayette, Indiana, have developed a potential new way to combat the massive illicit trade in counterfeit pharmaceuticals, which are a huge public health threat because they account for 10 percent of all global pharmaceutical sales, amounting to $200 billion every year. The new technology is based on edible silk proteins encoded with three distinctly colored fluorescent proteins, trace amounts of which can be arrayed into a barcode-like matrix, incorporated into a pharmaceutical, and read by a smartphone. Because the technology is entirely protein-based, the authors write, it should be safe to consume. ACS Central Science

Silkworms can produce edible, fluorescent silk cocoons (left side of left image); the proteins from the cocoons can be used in codes (right) to verify the authenticity of medications.

Passive immunization through gene therapy?

A phase 1 clinical trial involving eight people living with HIV/AIDS may be the first glimpse of a brand-new technology for protecting people against infectious diseases in the future. Led by the National Institute of Allergy and Infectious Diseases (NIAID), the study looked at the safety of injecting the eight people with a recombinant adeno-associated virus vector—the principal technology used in gene therapy. The idea was to administer genes that encode a powerful, “broadly neutralizing” antibody against HIV—a hybrid of vaccination and what’s known as passive immunization. Vaccines are great if they work, but past efforts to design HIV vaccines that raise broadly neutralizing antibodies directly have failed. Passive immunization relies on administering serum from disease survivors or monoclonal antibodies produced in the laboratory, and it works well, but it’s also expensive. Could this new approach be the best of both worlds? Nature Medicine

“Prefactual thinking” eases misinformation in people’s minds

Recalling a famous line from Seinfeld (“It’s not a lie if you believe it”), a new study shows that people are less likely to deem false claims as unethical if they think they could come true eventually. Conducted by researchers at London Business School, the work involved 3,607 people from 59 countries who were asked to judge false statements about consumer products, professional skills, and controversial political issues. People were less likely to regard outright lies as problematic if they believed the gist was correct, and when people entertained such “prefactual thoughts,” they were more inclined to share those lies on social media. This is significant, the researchers write, because the more acceptable people think a lie is, “the less accountable they will hold the people who tell it, and the more inclined they will be to spread the falsehood themselves.” Journal of Personality and Social Psychology