Data from: Opposing roles for Bmp signalling during the development of electrosensory lateral line organs

The lateral line system enables fishes and aquatic-stage amphibians to
detect local water movement via mechanosensory hair cells in neuromasts,
and many species to detect weak electric fields via electroreceptors
(modified hair cells) in ampullary organs. Both neuromasts and ampullary
organs develop from lateral line placodes, but the molecular mechanisms
underpinning ampullary organ formation are understudied relative to
neuromasts. This is because the ancestral lineages of zebrafish (teleosts)
and Xenopus (frogs) independently lost electroreception. We identified
Bmp5 as a promising candidate via differential RNA-seq in an
electroreceptive ray-finned fish, the Mississippi paddlefish (Polyodon
spathula; Modrell et al., 2017, eLife 6: e24197). In an experimentally
tractable relative, the sterlet sturgeon (Acipenser ruthenus), we found
that Bmp5 and four other Bmp pathway genes are expressed in the developing
lateral line, and that Bmp signalling is active. Furthermore,
CRISPR/Cas9-mediated mutagenesis targeting Bmp5 in G0-injected sterlet
embryos resulted in fewer ampullary organs. Conversely, when Bmp
signalling was inhibited by DMH1 treatment shortly before the formation of
ampullary organ primordia, supernumerary ampullary organs developed. These
data suggest that Bmp5 promotes ampullary organ development, whereas Bmp
signalling via another ligand(s) prevents their overproduction. Taken
together, this demonstrates opposing roles for Bmp signalling during
ampullary organ formation.