Chromosomes are masters of organization. These long strings of DNA fold down into an ensemble of compact structures that keep needed parts of the genome accessible while tucking away those that aren’t used as often. Understanding the complexity of these structures has been challenging; chromosomes are large systems, and deciphering the structure and dynamics requires a combination of experimental data and theoretical approaches. The FI-Chrom method, shared in a recent PNAS publication by Rice’s José Onuchic and Vinícius Contessoto, is a new and effective approach for creating 3D maps of chromosomes from real-world data.
FI-Chrom uses data from chromosome Hi-C maps. These maps break out the chromosome into units of length called beads — about 500,000 linear DNA bases each — and show how frequently each bead is close to other beads. This information shows only probabilities of any two beads being neighbors and no direct three-dimensional information. Imagine it as a logic puzzle where the rules, or parameters, read something like this: Bead A is 99% likely to be close to Bead B, 36% likely to be close to Bead C and 62% likely to be close to Bead D. A 3D model, the researchers knew, could be built by placing every bead in a space that didn’t violate any of the Hi-C map’s parameters. The only problem is that in Hi-C maps, there are hundreds of thousands of beads and tens of millions of mapped interactions showing bead closeness.
“We had chromosome maps that gave us, theoretically, 3D information, but we were really reading them in 2D space,” explains Onuchic, the Harry C. and Olga K. Wiess Chair of Physics and a corresponding author of the study. “Now, we have created FI-Chrom, an open-access program that can turn these Hi-C maps into 3D models of chromosomes.”
Deep-ultraviolet (DUV, λ < 200 nm) all-solid-state lasers, essential to modern scientific research and industrial manufacturing, are widely applied in fields from material analysis to lithography. Their commercialization depends heavily on high-performance nonlinear optical (NLO) crystals, but developing such crystals is hampered by strict requirements: They must simultaneously possess large second harmonic generation (SHG) responses, moderate birefringence, and wide bandgaps.
Borates have long been a research focus for their exceptional DUV transmission properties. Though materials like β-BBO and LBO have been developed, most cannot achieve DUV phase matching via direct frequency doubling. Fluoroborate systems have emerged as leading candidates due to structural diversity and superior performance, yet existing ones such as KBBF suffer from layered growth habits and toxic raw materials.
Moreover, DUV NLO crystals with chain-like polymerized [BO3]3- units are scarce. Thus, designing structural strategies to realize an ordered arrangement of functional units has become key to breaking the performance bottlenecks of DUV NLO materials.
Scientists have uncovered a previously unknown cluster of brain cells that may help explain differences in social behavior between males and females. The small neural circuit appears to function like an on/off switch, showing a striking pattern of activity that differs sharply by sex, an unusually clear contrast compared with most known brain sex differences, which tend to be more subtle and overlapping. Researchers also found that the circuit’s activity shifts with social and reproductive status, suggesting the brain may use this mechanism to adapt behavior across key life stages.
The new study was led by Dr. Tamar Licht and Dr. Dan Rokni from the Institute of Medical Research Israel-Canada (IMRIC) at the Hebrew University of Jerusalem and is published in the Proceedings of the National Academy of Sciences.
Cells routinely present peptide fragments from their proteome for immune surveillance, using major histocompatibility complex (MHC) proteins as a display window. In this study, researchers introduced viral peptides to be processed and displayed on cancer cells.
One molecule combines two approaches to waken dormant immunity against tumors by Laurel Oldach.