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

July 21, 2022

Good memories, bad memories, and the protein in between

Imbuing one’s memories with value judgments is an evolutionary adaptation that’s both a blessing and a curse. We may romanticize our own past, but the fact that we paint some memories with darker shades allows us to carry cautionary lessons and other wisdom through life. Now scientists at the Salk Institute in La Jolla, California, have discovered that a single, specific molecule in the brain is responsible for coloring our memories, good or bad. Using CRISPR to knock out genes in mice, they showed that a small neuropeptide called neurotensin in the brain’s basolateral complex of the amygdala is responsible for good and bad associations—and it’s likely the same mechanism in humans. “This is something that’s core to our experience of life, and the notion that it can boil down to a single molecule is incredibly exciting,” one of the researchers said in a press statement. Biological processes often turn out to be more complex than we first think, but it’s an exciting discovery nonetheless. Nature

The neuronal expression of various genes and proteins (tagged white, red, and green) is visible among the deep blue neurons of mouse brain cells (blue). Salk Institute

Gut bacteria and vitamin A metabolism

Vitamin A is an essential dietary nutrient that gets converted in the body into retinoic acid, a metabolite required for growth and development. This conversion process has largely been associated with our own human cells, but new research from Brown University in Providence, Rhode Island, and the University of Washington in Seattle suggests that good “commensal” bacteria in the gut also convert vitamin A into retinoids. They show that feeding Lactobacillus intestinalis probiotics to mice whose microbiomes had been depleted restored retinoic acid synthesis in their guts. They claim this is an emergent property of the gut, with no one single bacterial strain encoding all the enzymes required—but rather multiple gut bacteria sharing the necessary metabolic machinery. The work lays the foundation for developing new probiotic-based therapies, according to the researchers. Cell Host & Microbe

A protein target in rice to boost photosynthetic efficiency of crops

Researchers at the Chinese Academy of Agricultural Sciences in Beijing have found a “transcriptional regulator” protein called OsDREB1C that modulates DNA expression in rice and boosts the plant’s photosynthetic efficiency. Controlling its action has potential to improve grain yields, shorten growth cycles, and increase the amount of food produced by the same arable land. In field trials they showed that overexpressing this regulator increased rice yields by 41–68 percent while also decreasing the amount of fertilizer needed. This is an important first step toward a new green revolution because it could help cross-breeders or genetic engineers rapidly create new crop varietals that carry enhanced traits based on the action of this DNA regulator. Science

Red blood cells as never seen before

Anyone who has ever looked at a blood splatter under a microscope will know the familiar, disk-like appearance of erythrocytes, the simplest of all human cells—albeit a critically important player in health and disease. Now our picture of the simple red blood cell, as it’s more commonly known, has gotten a whole lot more detailed thanks to a new study from the University of Texas that highlights the 1,200 human proteins found in red blood cells and maps their dynamic interactions among the 100 or so molecular-machine-like protein complexes that determine the structure and function of the cells. Cell Reports

Deep learning speeds protein design

Researchers in David Baker’s lab at the University of Washington are describing two new methods this week for probing protein–protein interactions and predicting the critical component of proteins involved in binding and catalytic functions (a first step in the rational design of future drugs). They colorfully label their AI approaches “constrained hallucination” and “inpainting” and say they should be widely applicable to protein design. “We use these two methods to design candidate immunogens, receptor traps, metalloproteins, enzymes, and protein-binding proteins and validate the designs using a combination of in silico and experimental tests,” the researchers write. Science

Baguettes and bliss

Is there an inverse relationship between eating carbs and suffering depression? That’s what a study from Xi’an Jiaotong University in China suggests. Comparing 268,922 genetic variants associated with relative carbohydrate intake to 143,265 genetic variants associated with major depressive disorder, the researchers found a protective effect of higher carbohydrates in the diet, which appeared to lower depression risk. “These findings may inform prevention strategies and interventions directed towards relative carbohydrate intake and depression,” the researchers write. Maybe low-carb diets are just depressing?! Nature Human Behavior