Share

High ice nucleation temperature of zebrafish embryos: slow-freezing is not an option.

Author(s) : HAGEDORN M., PETERSON A., MAZUR P., et al.

Type of article: Article

Summary

Although fish embryos have been used in a number of slow-freezing cryopreservation experiments, they have never been successfully cryopreserved. In part this is because little is known about whether ice forms within the embryo during the slow-freezing dehydration process. The authors examined the temperature of intraembryonic ice formation (TIIF) and the temperature of extraembryonic ice formation (TEIF), using a cryomicroscope. They used both unmodified zebrafish embryos and those with water channels (aquaporin-3 or AQP3) inserted into their membranes to increase permeability to water and cryoprotectants, examined at 100% epiboly to the 6-somite stage. The following were examined: (1) spontaneous freezing of (external) solutions; (2) spontaneous freezing of solutions containing embryos; (3) the effect of preloading the embryos with cryoprotectants on TIIF; (4) whether preloading the embryos with cryoprotectant helps in survival after nucleating events; and (5) the damaging effects of extracellular nucleation events versus solution toxicity on the embryos. There was no significant difference amongst these means, thus adding cryoprotectant did not significantly lower the nucleation point. Adding embryos (preloaded with cryoprotectant or not) did not change the basic freezing characteristics of these solutes. In all these experiments, (TEIF) equaled (TIIF), and there was no difference in the freezing point of the solutions with or without the embryos. There was no difference in the freezing characteristics of embryos with and without aquaporins. The formation of intraembryonic ice was lethal to the zebrafish embryos in all cases. This outcome was not related to solution injury effects: 88-98% of embryos survived when exposed to a higher solute concentration with no ice present. These data suggest that slow-freezing is not a suitable option for zebrafish embryos. The mechanism of this high temperature nucleation event in zebrafish embryos is still unknown.

Details

  • Original title: High ice nucleation temperature of zebrafish embryos: slow-freezing is not an option.
  • Record ID : 2005-1501
  • Languages: English
  • Source: Cryobiology - vol. 49 - n. 2
  • Publication date: 2004/10

Links


See other articles in this issue (6)
See the source

Indexing