Australia possesses a large diversity of frogs, with over 200 native species currently recognised. Greater than 30 Australian native frog species, however, are presently listed as critically endangered, endangered or vulnerable; since 1979, four are considered extinct. The rate of native Australian frog loss is accelerating and as such there is an urgent need to develop methods to safeguard remaining species before they too become extinct.
Animal husbandry has proven invaluable for protecting many threatened species, but can suffer from issues of spatial constraint and genetic loss through inbreeding. Amphibian sperm cryopreservation for in vitro fertilisation has been developed for several species, yet methods for cryopreserving amphibian oocytes do not exist, and numbers of cryopreserved gametes are finite, meaning that once used, they cannot be used again. An important complement to animal husbandry and germ cell cryopreservation, overcoming these shortfalls, is somatic cell cryopreservation.
Somatic cells can be used as an infinite source of material for cloning initiatives, the safeguarding of nuclear and mitochondrial genomic DNA and, in theory, the eventual production of both sex gametes. Such techniques are well developed or in development for mammalian species and such cloning of vertebrates was first established using amphibian cells. The production of amphibian primary cell cultures and cell lines, however, remains a rare accomplishment. It is not intuitive to commence developing these techniques once an extinction has occurred.
With respect to Australian species, only Amphicell is able to repeatedly culture, freeze and thaw viable, karyotypically normal amphibian cells. No other examples of karyotypically validated Australian amphibian cell cultures exist in the literature. To date, fully validated cells from 10 different species representing eight different genera have been deposited in the Cryobank (see here). A further four partially validated cell cultures from four further species and six unvalidated tissue samples from six alternative species have also been included. Work is ongoing for full validation of these cell culture samples. Furthermore, and from published peer reviewed literature, Amphicell arguably has the largest representation of cultured, passaged, cryopreserved, thawed and karyotypically validated amphibian cells in the world, and most certainly Australian amphibian cells. It is aimed to extend with priority the cryobanking of prospectively validated cells from all current critically endangered, endangered or vulnerable Australian native amphibians where available.
Key words:
Frog, Australia, endangered, culture, cryopreservation, recovery, karyotyping