“…Moreover, using heptanol, a well-known gap junction blocker, the authors showed that calcium wave propagation, but not initiation, required fully functional gap junctions. Knickmeyer et al [10] investigated the role of bone morphogenetic protein (BMP) signaling, especially BMP4, in optic nerve pathfinding using a transgenic line encoding the zebrafish bmp4 gene under the heat-inducible hsp70 promoter, allowing precise overexpression timing. The authors thereby showed that BMP signaling was dynamic and overexpression of bmp4 impaired both the elongation of optic nerves and their crossing at the optic chiasm, suggesting for the first time a requirement for BMP signaling in retinal ganglion cell projections to the brain.…”