• 113 Developing a cryopreservation protocol for desert tortoise sperm (Gopherus agassizzii)

      Ravida, Nicole; Young, C.; Gokool, L.; Durrant, Barbara S. (2017)
      The desert tortoise (Gopherus agassizzii) is listed as threatened by the USA Fish and Wildlife Service and population declines continue to occur throughout most of their range. This species’ low reproductive rate, combined with the advanced age at which they reach sexual maturity, makes them vulnerable to multiple threats....
    • 98 Efficacy of commercial equine semen freezing extenders for cryopreservation of southern white rhinoceros (Ceratotherium simum simum) sperm

      Young, Carly; Ravida, Nicole; Pennington, Parker M.; Durrant, Barbara S. (2019)
      Once nearly extinct in the wild, the southern white rhinoceros is currently listed as near threatened by IUCN. This status is likely to change as poaching continues to escalate....
    • Animal cytogenetics

      Houck, Marlys L.; Lear, Teri L.; Charter, Suellen J.; Arsham, Marilyn S.; Barch, Margaret J.; Lawce, Helen J. (John Wiley & Sons, Inc., 2017)
      Chromosome karyotyping and gene mapping has been carried out for a wide variety of animal species and continues to expand. Cross-species chromosome painting, or Zoo-FISH, for example, can now be used to identify genome segments originating from a common ancestor that have been conserved between species for millions of years....
    • Challenges in the development of semen cryopreservation protocols for snakes

      Young, Carly; Ravida, Nicole; Durrant, Barbara S. (2019)
    • Development of a sperm cryopreservation protocol for the Argentine black and white tegu (Tupinambis merianae)

      Young, Carly; Ravida, Nicole; Curtis, Michelle J.; Mazzotti, Frank; Durrant, Barbara S. (2017)
      Of the 934 lizard species evaluated by the International Union for the Conservation of Nature (IUCN), at least one-third is threatened with extinction. However, there are no reports of semen cryopreservation efforts for lizards....
    • Exploring the limits of saving a subspecies: The ethics and social dynamics of restoring northern white rhinos (Ceratotherium simum cottoni)

      Ryder, Oliver A.; Friese, Carrie; Greely, Henry T.; Sandler, Ronald; Saragusty, Joseph; Durrant, Barbara S.; Redford, Kent H. (2020)
      The northern white rhino (Ceratotherium simum cottoni) is functionally extinct with only two females left alive. However, cryopreserved material from a number of individuals represents the potential to produce additional individuals using advanced reproductive and genetic rescue technologies and perhaps eventually a population to return to their native range. If this could and were done, how should it be done responsibly and thoughtfully. What issues and questions of a technical, bioethical, and societal nature will it raise that need to be anticipated and addressed? Such issues are explored in this article by an interdisciplinary team assembled to provide context to the northern white rhino project of the San Diego Zoo Global.
    • In Memory of Kurt Benirschke, MD: Pioneer in mammalian cytogenetics, founder of the Frozen Zoo®, and champion of comparative medicine

      Ryder, Oliver A. (2019)
      Kurt Benirschke, MD, was born on May 26, 1924, in Glückstadt, Germany and died on September 10, 2018 in La Jolla, California. Known to the broader genetics community as a pioneering investigator in the field of comparative mammalian cytogenetics, Benirschke’s scientific accomplishments spanned several fields....
    • Integrating current methods for the preservation of amphibian genetic resources and viable tissues to achieve best practices for species conservation

      Zimkus, Breda M; Hassapakis, Craig L; Houck, Marlys L. (2018)
      Global amphibian declines associated with anthropogenic causes, climate change, and amphibianspecific infectious diseases (e.g., chytridiomycosis) have highlighted the importance of biobanking amphibian genetic material. Genetic resource collections were the first to centralize the long-term storage of samples for use in basic science, including disciplines such as molecular evolution, molecular genetics, phylogenetics, and systematics. Biobanks associated with conservation breeding programs put a special emphasis on the cryopreservation of viable cells. These cell lines have a broader application, including the potential for genetic rescue and use in species propagation for population enhancement, such as captive breeding and reintroduction programs. We provide an overview of the most commonly used methods for the preservation of genetic resources, identify ways to standardize collection processes across biobanks, and provide decision trees to assist researchers in maximizing the potential use of their samples for both scientific research and the practice of species conservation. We hope that the collection and deposition of tissues preserved using methods that enable eventual cell line establishment will become routine practice among researchers, particularly herpetologists working in the field. While many major museums do not yet cryopreserve reproductive cells or cell lines, they contain the infrastructure and staff to maintain these collections if protocols and procedures are adapted. Collaboration between organizations can play an important future role in the conservation of amphibians, especially biobanks associated with research institutions and those pioneering techniques used in breeding programs.
    • Pretreatment of Addra gazelle (Nanger dama ruficollis) spermatozoa with cholesterol-loaded cyclodextrins improves cryosurvival

      Wojtusik, Jessye; Pennington, Parker M.; Songsasen, Nucharin; Padilla, Luis R.; Citino, Scott B.; Pukazhenthi, Budhan S. (2016)
      ...Our aim was to characterize Addra gazelle (Nanger dama ruficollis) ejaculate traits and to assess the effects of cholesterol-loaded cyclodextrin (CLC) on sperm cryosurvival. Fresh ejaculates were treated with CLC (0, 0.5, 1.5, 3.0, and 6.0 mg/ml) prior to cryopreservation.... Reported advances will facilitate establishment of a frozen repository and support the genetic management of this critically endangered north African desert antelope.
    • Rewinding the process of mammalian extinction

      Saragusty, Joseph; Diecke, Sebastian; Drukker, Micha; Durrant, Barbara S.; Friedrich Ben-Nun, Inbar; Galli, Cesare; Göritz, Frank; Hayashi, Katsuhiko; Hermes, Robert; Holtze, Susanne; et al. (2016)
      With only three living individuals left on this planet, the northern white rhinoceros (Ceratotherium simum cottoni) could be considered doomed for extinction. It might still be possible, however, to rescue the (sub)species by combining novel stem cell and assisted reproductive technologies. To discuss the various practical options available to us, we convened a multidisciplinary meeting under the name “Conservation by Cellular Technologies.” The outcome of this meeting and the proposed road map that, if successfully implemented, would ultimately lead to a self-sustaining population of an extremely endangered species are outlined here. The ideas discussed here, while centered on the northern white rhinoceros, are equally applicable, after proper adjustments, to other mammals on the brink of extinction. Through implementation of these ideas we hope to establish the foundation for reversal of some of the effects of what has been termed the sixth mass extinction event in the history of Earth, and the first anthropogenic one. Zoo Biol. 35:280–292, 2016. © 2016 The Authors. Zoo Biology published by Wiley Periodicals, Inc.
    • Viable cell culture banking for biodiversity characterization and conservation

      Ryder, Oliver A.; Onuma, Manabu (2018)
      Because living cells can be saved for indefinite periods, unprecedented opportunities for characterizing, cataloging, and conserving biological diversity have emerged as advanced cellular and genetic technologies portend new options for preventing species extinction. Crucial to realizing the potential impacts of stem cells and assisted reproductive technologies on biodiversity conservation is the cryobanking of viable cell cultures from diverse species, especially those identified as vulnerable to extinction in the near future. The advent of in vitro cell culture and cryobanking is reviewed here in the context of biodiversity collections of viable cell cultures that represent the progress and limitations of current efforts. The prospects for incorporating collections of frozen viable cell cultures into efforts to characterize the genetic changes that have produced the diversity of species on Earth and contribute to new initiatives in conservation argue strongly for a global network of facilities for establishing and cryobanking collections of viable cells.