1. Secret of the Sexes
The evolution of gender required that gene expression be balanced between males’ XY chromosomes and females’ XX, but how does that happen? New research on fruit flies suggests the secret maybe as simple as GAGAGA: a repeating DNA sequence that’s crucial for binding the protein CLAMP to the X chromosome. Together with a protein called “male-specifc lethal,” CLAMP boosts gene expression of the single X chromosome so males can live. Erica Larschan, PhD, senior author of the study in PLoS Genetics and the Richard and Edna Salomon Assistant Professor of Molecular Biology, Cell Biology, and Biochemistry, says the same process is in play in some other flies; now she’s trying to figure out if mammalian gender depends on GA repeats, too.