In Vivo Imaging of Membrane-Associated Glycans in Developing Zebrafish

TLDR

Glycans are attractive targets for molecular imaging but have been inaccessible because of their incompatibility with genetically encoded reporters. The study demonstrates noninvasive imaging of glycans in live developing zebrafish using a chemical reporter strategy. Zebrafish embryos were treated with an unnatural sugar to metabolically label cell‑surface glycans with azides, then reacted with fluorophore conjugates via copper‑free click chemistry, enabling subcellular‑resolution visualization during development, and a multicolor detection strategy allowed spatiotemporal analysis of glycan expression and trafficking. At 60 h post‑fertilization, increased de novo glycan biosynthesis was observed in the jaw region, pectoral fins, and olfactory organs, and the multicolor detection revealed spatial patterns of glycan expression and trafficking that would be undetectable with conventional imaging.

Abstract

Glycans are attractive targets for molecular imaging but have been inaccessible because of their incompatibility with genetically encoded reporters. We demonstrated the noninvasive imaging of glycans in live developing zebrafish, using a chemical reporter strategy. Zebrafish embryos were treated with an unnatural sugar to metabolically label their cell-surface glycans with azides. Subsequently, the embryos were reacted with fluorophore conjugates by means of copper-free click chemistry, enabling the visualization of glycans in vivo at subcellular resolution during development. At 60 hours after fertilization, we observed an increase in de novo glycan biosynthesis in the jaw region, pectoral fins, and olfactory organs. Using a multicolor detection strategy, we performed a spatiotemporal analysis of glycan expression and trafficking and identified patterns that would be undetectable with conventional molecular imaging approaches.