Hydrocolloid Coating of Xenopus laevis Embryos

A novel technology for coating single cells and embryos with thin hydrocolloid (watersoluble polymer) films has been invented and patented. Coating is different from entrapment and immobilization in that the coating around the cell is thinner, comprising only a small fraction of the cell or embryoʹs diameter. Xenopus laevis embryos were coated with thin films of low-methoxy pectin (LMP), alginate, and iand k-carrageenans. These gums have different compositions and structures and as such created different coatings around the fertilized cells. All coated embryos appeared to develop normally, similar to noncoated embryos. Elemental detection by ICP-AES spectroscopy revealed that the embryo can control the diffusion of excess ions to which it is exposed during the coating process. The coatings delayed hatching by 18-24 h. Consequently, at hatch the embryos were at a more developed stage than their noncoated counterparts. The hydrocolloid coating reduced the thickness of the natural jelly coating (JC). With the i-carrageenan coating, percent hatch was maximal, while with LMP it was minimal, as a result of the filmsʹ mechanical properties and thicknesses. LMP and alginate created smoother coatings than the carrageenans. Potential interactions between the coating and the natural JC are hypothesized. Overall, coatings appear to be a suitable tool for laboratories interested in performing longer-term experiments with embryos.