In this blog, Mary Zelinski, PhD continues her reports from the annual meeting of the Society for Cryobiology held in Corvallis, Oregon, July 24-27. In this post, she relay's the findings of Dr. Pukazhenthi, on the importance of fertility preservation for endangered species. Read the first and second posts on Cryo2011 here.
By Mary Zelinski, PhD-Dr. Budhan Pukazhenthi, Reproductive Physiologist at the Center for Species Survival, Department of Reproductive Sciences, Smithsonian Conservation Biology Institute, gave a fascinating presentation on “Cryopreserving Endangered Species Gametes, Embryos and Gonadal Tissue: Challenges, Successes and Future Directions.” He noted that the field of cryobiology has long been touted as a valuable tool for the conservation of endangered wildlife species, and that in the last 25 years cryobiology has gradually emerged as a contributing science to the field of conservation. The systematic collection, storage and use of biomaterials, i.e. “Genome Resources Banking”, has yielded a dynamic repository of biological specimens being used to enhance genetic management of sustainable populations.
He outlined four specific challenges facing reintroduction of genetic diversity into future generations of wildlife: 1) limited fundamental knowledge about individual species, including the difficulty of collecting gametes from some species; 2) species diversity in gamete and embryo structure, function and cryosensitivity; 3) variation among donors; and 4) influence of lack of heterozygosity on cyrosurvival. Since results from one species rarely translate to another, there is a critical need for continuous, species-specific cryobiological research.
Use of this overall approach has resulted in a number of conservation success stories that go beyond milestone births of one or two offspring from frozen sperm or embryos. He cited examples such as the use of cyropreserved sperm for the past two decades in the recovery program of the black-footed ferret and the production of multiple litters of two felid species, Brazilian ocelot and caracal, from cryopreserved embryos. He predicted that wildlife programs will benefit from fertility preservation strategies currently being developed for humans. Initial efforts in cryopreservation of ovarian tissue, seminiferous tubules and testicular tissue, in follicle maturation and germinal-vesicle storage show potential for use in species conservation.
Dr. Pukazhenthi also noted that most cyro-tools are considered in the context of mammals, but that there has been significant progress in other taxa, including birds, amphibians and marine life. His laboratory has made progress in cryopreservation of coral sperm and fish embryos. He concluded by saying that an appreciation for Genetic Resources Banking is emerging beyond the immediate interest of cyrobiologists and reproductive biologists wherein cryobiology is not only being recognized as a method for storing and moving important genomes, but as an essential component of the ability to monitor genetic diversity and diseases in rare populations.