Human Brain Undergoes Major Midlife Reorganization: A detailed molecular map of the human hippocampus suggests brain aging involves a pronounced biological transition between roughly ages 50 and 75 rather than simply gradual decline. Researchers analyzed gene expression, chromatin accessibility, DNA methylation and three-dimensional genome organization in individual brain cells. During midlife, embryonically derived microglia—the brain’s resident immune cells—declined and were increasingly replaced by cells resembling blood-derived immune cells with stronger inflammatory signatures. Astrocytes and cells supporting the blood-brain barrier also decreased, while the normally organized 3D architecture of DNA progressively deteriorated across several cell types. The study, published in Science, could help explain why aging dramatically increases vulnerability to neurodegenerative diseases by identifying coordinated changes in immune, vascular and genomic regulation that emerge during later adulthood. (ScienceDaily)
Webb Finds Tiny Brown Dwarfs Near Planetary Mass: The James Webb Space Telescope has pushed observations of star formation into an extraordinarily low-mass regime, identifying brown dwarfs weighing only about twice as much as Jupiter. Astronomers surveyed IC 348, a young star-forming region approximately 1,000 light-years away in Perseus, to investigate how small an object can form through the same gravitational collapse that produces stars. Brown dwarfs occupy the boundary between stars and giant planets: they form from collapsing molecular clouds but never accumulate enough mass to sustain ordinary hydrogen fusion. Webb’s sensitivity also revealed young stars producing powerful jets that collide with surrounding gas and dust. Finding objects this small through a star-like formation process could help astronomers determine where brown dwarfs end and planets begin while placing new constraints on theories explaining how molecular clouds fragment into stars and substellar objects. (NASA Science)
Fecal Transplants Rapidly Ease Immunotherapy Colitis: Fecal microbiota transplantation may offer cancer patients a faster, less immunosuppressive treatment for severe intestinal inflammation caused by checkpoint immunotherapy. In an early Phase I/II trial from MD Anderson Cancer Center, 10 of the first 13 patients—nearly 77%—improved following FMT, with symptoms subsiding after a median of just 1.5 days. Eight responders remained in remission during follow-up. The treatment transfers carefully screened donor gut microbes to restore a healthier intestinal ecosystem, potentially reducing reliance on steroids and biologic drugs that suppress immunity and can complicate cancer treatment. Responders developed increases in bacteria associated with healthier intestines and decreases in inflammation-linked microbes. The results are encouraging but preliminary: only 13 patients were included, and larger randomized trials comparing FMT with standard therapy are planned. (Medical Xpress)
Robots Discover Hidden Chemistry in 135-Year-Old Reaction: Robotic experimentation and artificial intelligence have uncovered an unexpected pathway inside the Biginelli reaction, a classic chemical reaction studied since 1891. Rather than using automation simply to optimize production of a known molecule, researchers systematically tested 960 combinations of reaction conditions, effectively mapping a multidimensional chemical “hyperspace.” The search revealed a previously unknown branch producing complex bicyclic molecules. AI-assisted mechanistic analysis indicated an unusual pseudo-seven-component transformation in which seven molecules of the starting materials ultimately contribute to a single complex product. Some resulting compounds also displayed unusual self-assembly and selective binding to zinc and barium ions, potentially useful for sensing and molecular-recognition applications. Published in Nature Synthesis, the work suggests automated laboratories could become discovery engines that systematically expose overlooked chemistry hidden even inside reactions scientists have investigated for more than a century. (Phys.org)
Neurons Use Genetic Switches to Guide Their Axons: Neuroscientists have challenged a longstanding explanation for how developing neurons wire themselves with extraordinary precision. Researchers at Brown University studied commissural neurons, whose axons cross the spinal cord’s midline before sharply changing direction toward their next destination. Scientists had generally assumed that guidance decisions were controlled primarily at the growing axon tip. Instead, single-cell RNA sequencing revealed that neurons switch entire groups of genes on and off in their cell bodies as axons pass developmental waypoints. Those genetic changes cause different guidance molecules to appear at the axon tip, redirecting its growth. Published in PNAS, the research also generated gene-expression data from more than 12,000 developing neurons. Understanding these genetic programs could eventually help researchers solve a central problem in spinal-cord and stroke repair: regenerating axons is possible experimentally, but steering them back to the correct targets remains exceptionally difficult. (Brown University)