Cryopreservation of Fish Embryos: Permeability of the Yolk Syncytial Layer in Dechorionated Zebrafish EmbryosAn important limitation that the aquaculture industry faces is the lack of reliable strains and breeding populations. One way to overcome this limitation is to use low temperature freezing techniques (cryopreservation) to preserve sperm and eggs of fish species; this has been done for most domesticated animals, birds and a few endangered wildlife species. While cryopreservation of fish sperm is reliably done, preservation of fish eggs and fertilized eggs (embryos) is far more difficult. Yolk-laden fish embryos can be thought of as a complex, multi-compartmental system: the components are separated by distinct cellular boundaries. To have effective cryopreservation, it is essential that cryoprotectants be transferred to each component of the embryo prior to freezing. Mary Hagedorn and Frederick Kleinhans have been studying the cryopreservation process in zebrafish and have discovered that the boundary separating the developing embryo or blastoderm from the yolk (called the yolk syncytial layer) is impermeable to a number of commonly used cryoprotectants. When these chemicals are absent, water in the yolk is thought to form large ice-crystals that ultimately cause irrevocable damage to the embryo. In this continuing project, Hagedorn and Kleinhans are examining how this damage occurs and seek clues to the actual mechanism that allows the yolk syncytial layer to block transport of cryoprotectant. They will use new methods designed to permeate this layer in a way that allows effective cryopreservation. Success with zebrafish could have far-reaching implications that extend to economically important species. |
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1998-1999
Mary M. Hagedorn National Zoological Park Smithsonian Institution Fredrick W. Kleinhans Indiana University/Purdue University at Indianapolis 1996-1990 Mary M. Hagedorn, David E. Wildt and William F. Rall Ntional Zoological Park Smithsonian Institution |
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