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

August 11, 2022

Reprogramming plant growth through Boolean logic

How a plant takes root in the soil is a key factor determining its growth, and synthetic biologists have long dreamt of finding ways of controlling this basic process to confer resilience against drought and nutrient deficiencies and optimize plant growth. Now scientists at Stanford University have shown one way to do this—by designing synthetic genetic circuits to reprogram root growth. Using the mustard green Arabidopsis thaliana, they created a library of synthetic transcription factors and promoters, which are basic regulators of gene expression at the molecular level. They showed they could construct genetic circuits from these transcriptional regulators that predictably altered the root structure of the plant by controlling gene expression through Boolean logic. The same approach, they write, could be used to reprogram growth traits in other plants. Science

Synthetic genetic circuits designed to rewire gene expression in plant roots may be used to change the way they grow, according to new research. Jennifer A. N. Brophy

An artificial neuron that uses real neurotransmitters

While it’s not exactly the realization of “wetware” we have covered in the past, the announcement this week of a chemically mediated artificial neuron that responds to and releases the chemical neurotransmitter dopamine may be a step in that direction. Researchers at Nanjing University of Posts and Telecommunications in China and Nanyang Technological University in Singapore created the artificial neuron from carbon-based electrochemical sensors, which detect the dopamine, and heat-responsive hydrogels, which release it. As a demonstration they showed their artificial neurons detect dopamine in a type of rat cell and activate that same type of cell by releasing dopamine in response. This allowed them to control the movement of a mouse leg and robot hand with the technology. Nature Electronics

Potential MRI biomarker of cognitive fatigue

Thinking for a living is exhausting, and anyone who has put their feet up on the couch to watch mindless TV after a long day as a hardworking professional knows this—even though the precise neuroscience that explains exactly how daylong knowledge work leads to cognitive fatigue has never been understood. Now researchers at Pitié-Salpêtrière University Hospital and Sorbonne University in Paris, France, think they cracked it: Blame your brain’s glutamate for your mental exhaustion. Using MRI, they monitored various brain metabolites in two groups of people doing either high-demand or low-demand cognitive tasks throughout a mock workday. This allowed them to validate glutamate accumulation in the lateral prefrontal cortex as a cognitive fatigue biomarker. This marker was only present in the high cognitive demand test group, who also showed a reduction of pupil dilation during decision-making and a preference toward effortless behaviors with immediate gratifications at the end of the day. So maybe you should postpone important decisions until tomorrow. Current Biology

Bacterial swarming inspires new synbio tool

Researchers at the University of Arizona have discovered a way to build multicellular materials from the ground up through synthetic biology by inserting four different adhesion molecules on the surfaces of Escherichia coli cells. By growing turning loose the growing, swarming cells on Petri dishes, they were able to predictably program their growth into tiled 2D “tessellation” patterns reminiscent of M.C. Escher, Islamic architecture, and the Tetris video game. Working out the 4-bit logic of how to build these patterns, the researchers say this could be a new basic tool for synthetic biology. The same adhesion molecules could be engineered onto other cell types with lots of practical applications, including new molecular diagnostics, programmable self-growing materials, and artificial tissues. Nature

AI helps doctors treat back pain via teletherapy

A test of human teletherapy and AI-assisted teletherapy has shown great results in a small study of 278 people in the Veterans Affairs health system. Researchers at the University of Michigan compared the effectiveness of psychiatric treatments delivered through weekly calls by a clinician to treatment overseen by a clinician but with an AI assist, which determined whether a doctor’s call was needed each week based on the patient’s progress. The people in the study were suffering chronic back pain, and the treatment consisted of 10 weeks of cognitive behavioral therapy, a safe and effective alternative to opioids. Cognitive behavioral therapists are often in high demand, and the study showed an AI could potentially lift some of this burden. At six months, the people in the AI-assisted group showed as good or better improvement in physical function and pain intensity, while the therapists were able to cut the time they spent by more than half. JAMA Internal Medicine

A gene expression atlas for cows

A consortium of researchers at the USDA’s Agricultural Research Service in Beltsville, Maryland, the University of Edinburgh in Scotland, China Agricultural University, Beijing, and the Chinese Academy of Sciences have constructed a genetic atlas of the common cow, a resource for agriculture and animal husbandry they call the Cattle Genotype-Tissue Expression atlas. Based on 7,180 publicly available RNA-sequence samples, the atlas describes the gene expression landscape of dozens of cell types in the cow, characterizes gene expression across 23 distinct tissues, and links gene expression in the different tissues to “43 economically important traits.” The same consortium is also applying the approach to other livestock, including pigs, sheep, goats, and chickens. Nature Genetics