Every cell in a living organism carries the same DNA, but they perform wildly different jobs because they follow different genetic instructions. To truly understand how specific cells work, scientists need to monitor two things at once. They must track which genes are actively turned on, measured through a technique called RNA-seq, and how physically open or accessible the tightly packed DNA is, measured via ATAC-seq. Running both of these measurements simultaneously in a single cell has traditionally been a complex hurdle.
Now, researchers have introduced a streamlined protocol called easySHARE-seq to clear that hurdle. The new tool allows scientists to simultaneously measure both gene expression and chromatin accessibility within individual cells. By improving upon older techniques, easySHARE-seq manages to capture over 1.5 times more genetic transcripts per cell than comparable methods.
The updated protocol also captures longer stretches of genetic code. It extends the usable sequence length to 300 base pairs, a massive 200 base pair increase over previous iterations. This extra length helps researchers spot tiny genetic variations and analyze signals specific to certain genetic alleles. Better yet, the process cuts costs by eliminating the need for a dedicated sequencing run.
When we picture DNA, we often think of a flat twisted ladder. But inside a cell, the genome is folded into complex three-dimensional shapes. The way this genetic instruction manual is folded dictates how a cell actually reads its genes. To understand how this microscopic origami evolved over billions of years, researchers mapped the 3D genome organization of 1,025 different species, spanning from simple bacteria to complex animals, plants, and fungi.
By analyzing vast amounts of structural data, the scientists discovered that our ancient, single-celled ancestors likely had completely random, unstructured genomes. Over time, two distinct architectural styles emerged. Most bacteria adopted a strategy called "global folding," which is a broad spatial organization of the entire genome. As evolution marched on, this global folding technique became the dominant architectural style in the plant kingdom.
Meanwhile, the animal kingdom took a different path. The researchers found that animals increasingly relied on a "checkerboard" pattern, where specific compartments of genetic material are spatially sorted and grouped together. While early traces of this checkerboard style can be seen in archaea (ancient single-celled microbes), the pattern grew highly complex throughout animal evolution.
How does a single cell transform into a complex human body? The secret lies in our DNA, but not just the genes themselves. It is also about when and where those genes are turned on or off. To decode this process, researchers created the Human Development Multiomic Atlas. By examining more than 800,000 fetal cells across 12 different organs, they mapped the exact locations where our genetic material is open and active during the crucial period of 10 to 23 weeks after conception.
To make sense of this massive biological map, the team used deep-learning models to analyze the DNA. They discovered 508 specific genetic patterns, or motifs, that act like molecular switches. These switches control chromatin accessibility, which refers to how tightly or loosely our DNA is packed. When DNA is loosely packed, it is accessible to transcription factors, the specialized proteins that read our genes.
The researchers found that these proteins cooperate using a distinct biological grammar. Sometimes they require a strict "hard syntax" with exact spacing and orientation, while other times they use a flexible "soft syntax" to coordinate their activity. While most of these newly discovered switches help open the DNA to enhance activity, the researchers noted that a small subset works by reducing accessibility.
Amyotrophic lateral sclerosis (ALS) is a severe condition that causes a progressive loss of nerve cells in the brain and spinal cord. While scientists have spent decades studying why these neurons fail, recent research published in Nature Neuroscience points to an unexpected culprit. The study reveals that the immune system is not merely reacting to the disease, but actually acts as an active driver of ALS pathology.
To uncover this, researchers used advanced techniques called single-cell and spatial transcriptomic profiling. These tools allow scientists to look at the genetic activity of individual cells and map their exact physical locations in the body. Using these methods, the team observed that immune cells from the bloodstream are infiltrating the central nervous system. Once there, these immune cells undergo a reprogramming process that directly links changes in the blood to the severe spinal cord damage seen in ALS patients.
