Biobanking efforts and new advances in male fertility preservation for rare and endangered species

Abstract

Understanding and sustaining biodiversity is a multi-disciplinary science that benefits highly from the creation of organized and accessible collections of biomaterials (Genome Resource Banks). Large cryo-collections are invaluable tools for understanding, cataloging, and protecting the genetic diversity of the world's unique animals and plants. Specifically, the systematic collection and preservation of semen from rare species has been developed significantly in recent decades with some biobanks now being actively used for endangered species management and propagation (including the introduction of species such as the black-footed ferret and the giant panda). Innovations emerging from the growing field of male fertility preservation for humans, livestock species, and laboratory animals are also becoming relevant to the protection and the propagation of valuable domestic and wild species. These new approaches extend beyond the “classical” methods associated with sperm freezing to include testicular tissue preservation combined with xenografting or in vitro culture, all of which have potential for rescuing vast amounts of unused germplasm. There also are other options under development that are predicted to have a high impact within the next decade (stem cell technologies, bio-stabilization of sperm cells at ambient temperatures, and the use of genomics tools). However, biobanking efforts and new fertility preservation strategies have to expand the way beyond mammalian species, which will offer knowledge and tools to better manage species that serve as valuable biomedical models or require assistance to reverse endangerment.

The Phospholipid Composition of Kangaroo Spermatozoa Verified by Mass Spectrometric Lipid Analysis

“…Figure 3). For 22:3 only one standard substance, 22:3 n-3 (cis- 13,16,19), is commercially available. This n-3 fatty acid is not detected by GC (retention time 51 min).…”

“…Among 66 species, ten are graded as near-threatened, nine as vulnerable, nine as endangered, four as critically endangered, and four as extinct in 2016 (http://www.iucnredlist.org, 2016). In addition to protecting their habitat, artificial reproduction techniques, including successful cryopreservation of the gametes, are increasingly important for saving endangered species from extinction [19]. Even though there are already many studies on the cryopreservation of marsupial sperm, their successful cryopreservation remains a substantial challenge.…”

“…The morphology of mitochondria is particularly sensitive to glycerol, and cryopreservation leads to a complete or at least partial loss of the mitochondrial contents [22] and subsequently to a loss of motility. As reviewed by [19], glycerol concentration needs to be more than 15% to obtain any post-thaw motility at 35 °C in macropodid spermatozoa. Below 20 °C a post-thaw motility of 70% can be observed.…”

“…For the GC experiments performed in this study all peaks could be assigned except for one with a retention time of 48.5 min. For 22:3, only an n-3 standard (cis- 13,16,19) is commercially available, which exhibits a retention time of 51 min. 22:3 is a very unusual fatty acid.…”

The potential and pitfalls of de‐extinction

“…Perhaps more problematic for larger scale application in de‐extinction is that due to various incompatibilities, this method is (most likely) limited to animals that can (or could in the past) naturally interbreed. Furthermore, even if such incompatibilities can be overcome, success will require excellent understanding of the reproductive biology of the surrogate (something we lack for most vertebrate species, Comizzoli ) and will only be applicable to extinct species from which exceptionally well‐preserved cells can be found.…”