Genetics

Scientists generated rats with multiple inherited mutations in their mitochondrial DNA through a single direct procedure. Traditional breeding cannot combine these energy-producing genetic defects because offspring inherit mitochondrial DNA exclusively from the mother. The team bypassed this barrier by injecting base-editing tools straight into single-cell embryos to modify several targets at once.

Researchers used deep learning models to build synthetic DNA enhancers that turn on specific genes inside living mouse embryos. Scientists previously struggled to predict whether artificial genetic sequences could navigate the biological complexity of a living mammal rather than isolated cells in dishes. The computational tools assemble new regulatory DNA letters from scratch to direct gene activity exclusively within targeted tissues.

Genetic patterns thought to prove that modern humans interbred with Neanderthals actually stem from variations in human mutation rates. This finding challenges the widely accepted view that people outside Africa carry surviving pieces of the Neanderthal genome. The mathematical test used to detect ancient interbreeding assumes mutation rates stay constant between groups, but changing rates generate the exact same genetic signal.

Accumulating passenger mutations in blood stem cells provide a direct measure of clonal expansion during human aging. Scientists long assumed only specific cancer driver mutations caused these blood stem cell clones to outgrow their neighbors. Instead, dividing stem cells copy passive genetic tags that multiply whenever shared cellular growth pathways activate.

A new platform called Spatial Hi-C-RNA maps three-dimensional DNA architecture and gene expression together on the same tissue slice. Biologists often assume measuring active RNA transcripts alone captures every meaningful cell state across a tissue sample. Instead, the technique pairs direct physical contact points along packed DNA fibers with the RNA messages produced at those exact tissue locations.

Unseen protein sequences outside the boundaries of natural biology can carry out functional molecular tasks. Scientists long assumed that billions of years of evolution had already mapped out most workable amino acid combinations. Instead, unmapped chains of amino acids physically link together and fold into active molecules that perform biological duties without matching known wild relatives.