Cover image

An emu and several other bird species are shown with a cell nucleus, including segregated heterochromatin (gray blue) and euchromatin (orange) with euchromatin in the nuclear center and heterochromatin at the nuclear periphery. The heterochromatin and euchromatin also form the letters Z and W, respectively, which points to the distinctive ZW sex chromosomes of birds. Emu has a largely euchromatic W Chromosome, while most other birds have a heterochromatic W Chromosome. In this issue, a new chromosome-level genome assembly of a female emu is generated and compared to those of other birds and one turtle species, shedding light on the evolution of avian genome structure, nuclear architecture, and sex chromosomes. (Cover illustration concept by Jing Liu and Qi Zhou, illustrated by Shuqing Cheng at Chengdu Eyeseemedical Technology Co., Ltd. (www.eyeseemedical.com). [For details, see Liu et al., pp. 497–511.])