Amphibian sperm chromatin structure and function and its relevance to sperm preservation

The focus of amphibian conservation has recently shifted towards the establishment of genetic resource banks that, in association with assisted reproductive technologies (ARTs), can potentially function as a means of securing anuran biodiversity at risk of extinction. Gamete cryopreservation is one such technology that provides a mechanism for sustaining the genetic viability of small fragmented populations, and, therefore, has been championed as an important component of endangered amphibian conservation. Current technologies for gamete cryopreservation, however, are not without their adverse effects on cellular functions, and although there is an increasing body of literature regarding possible effects on traditional sperm parameters (such as motility and plasma membrane integrity), biologists know little about the effect of the freeze-thaw process on sperm DNA integrity. In addition, despite extensive literature detailing sperm chromatin organization and DNA fragmentation in mammalian species, current knowledge pertaining to amphibian sperm DNA is limited. Consequently, this review assembles current information on amphibian sperm chromatin organization and explores the effects of cryopreservation on DNA integrity; it is designed to prompt those working in the field of amphibian ART to consider the potential significance of sperm DNA damage as it relates to the assessment of amphibian spermatogenesis and sperm preservation procedures