In this week's Nature, a team led by University of Geneva scientists report new insights on Down's syndrome based on an analysis of a pair of identical twins in which only one twin had an extra copy of chromosome 21. While it had been thought that most traits associated with Down's syndrome are caused by altered gene expression from the additional chromosome, the researchers show that differential gene expression is organized in domains along all chromosomes. They also saw similar patterns of altered gene expression in a mouse model of the condition, indicating that these gene expression dysregulation domains are conserved in other mammals.
Meanwhile, in Nature Biotechnology, researchers from the UK's Medical Research Council Laboratory of Molecular Biology and the University of Cambridge report on a method for identifying proteins synthesized at specific times in cells of interest in vivo. Called SORT-M — short for stochastic orthogonal recoding of translation with chemoselective modification — the approach involves modifying cells to express an orthogonal aminoacyl-tRNA synthetase/tRNA pair to enable the incorporation of chemically modifiable analogs of amino acids at diverse sense codons in cells in rich media. The group applied SORT-M to fruit flies fed standard food to label and image proteins in specific tissues at precise developmental stages with diverse chemistries, and then they used it to identify proteins synthesized in germ cells of the fly ovary without dissection.