This month’s cover image is inspired by the Article on p. 528 of this issue, by Jeff Wall, Nicola Illing, Nadav Ahituv and colleagues. The paper reports the genome of the bat Miniopterus natalensis and transcriptional dynamics in the developing bat wing. This species, one of a group known as vesper bats, is also known as the Natal long-fingered bat and is found in parts of Africa.

The image chosen for the cover is a frontal view of a bat embryo at a late stage of development (stage CS21) taken by study co-author Mandy Mason. This developmental stage is known as
“Translucent Wing”, as you can clearly see the skeletal structures in the wing and the membrane between the outstretched digits. The embryo in this image was stained with Alizarin red (maroon-red-pink) for bone and Alcian blue (blue-cyan) for cartilage. The image was actually taken as part of an earlier study to understand the progression of limb development in this species and to compare it with that of the mouse.

The current study presents not only the genome sequence of the Natal long-fingered bat, but also RNA-seq and ChIP-seq (for H3K27ac and H3K27me3) profiling of the developing limbs. The authors identified more than 7,000 genes that were differentially expressed between the forelimbs—the eventual wings—and the hindlimbs. Through comparative genomics analyses, they found nearly 3,000 regions showing evidence of accelerated evolution along the bat lineage that overlapped with H3K27ac peaks, suggesting that these are candidate enhancer regions for wing development. “This study offers a comprehensive resource for future work in comparative limb development,” co-author Mandy Mason told us. “Aside from the results that we have presented in this paper, these open datasets can be queried to help answer additional questions that may be asked by both our and other research groups.”