Preserving Genetic Lines for Conservation
Capturing genetic diversity present in sperm, eggs, and embryos provides the potential to sustain or reanimate valuable genetic lines in support of conservation. Using a variety of techniques, including scanning and transmission electron microscopy, our studies assess sperm viability by motility, swimming speed, and force analysis, as well as staining for acrosomal and plasma membrane integrity. Oocyte and embryo cryosurvival are assessed by in vitro embryo development. The ultimate goal of this project is to create genetically valuable offspring using thawed gametes in assisted reproduction. The judicious use of cryopreserved gametes and embryos provides the means to maximize genetic diversity by combining the genomes of individual animals separated by time or space.
Although germplasm from all genetically valuable animals are harvested and frozen opportunistically, the focus of in-depth studies is carnivores and hoofed animals. The domestic dog, cat, and cow serve as models to optimize methodologies which are extrapolated to related exotic species. We are expanding our work to include development of species-specific in vitro oocyte maturation, sperm capacitation, fertilization (including intracytoplasmic sperm injection), and embryo culture techniques for fresh and cryopreserved germplasm. Accomplishments to date include the first hatching of three Chinese pheasant species following artificial insemination with cryopreserved sperm, in vitro fertilization via intracytoplasmic sperm injection in the southern white rhinoceros using postmortem harvested oocytes and sperm cryopreserved for over 20 years, and the successful cryopreservation of sperm from the red diamond rattlesnake as a model for endangered snakes.
Finally, the Reproductive Physiology and Genetics Divisions are collaborating to develop a major new program in stem cell banking and utilization for the preservation of genetic resources.