Vitrification as a method for genome resource banking oocytes from the endangered Tasmanian devil (Sarcophilus harrisii)

Abstract

Populations of Australia's largest terrestrial marsupial carnivore, the Tasmanian devil (Sarcophilus harrisii), are rapidly declining in the wild due to Tasmanian Devil Facial Tumour Disease (TDFTD). One tool which can reduce the loss of genetic diversity is genome resource banking. This study examines the application of an oocyte vitrification protocol, initially developed in a model marsupial carnivore, to the endangered Tasmanian devil. Ovarian tissue was transported to the laboratory on ice from Tasmania which took up to 48 h. Individual granulosa oocyte complexes (GOC) were isolated enzymatically and the viability of oocytes from primary GOC was assessed immediately following isolation or after exposure to cold shock, vitrification and thawing media without exposure to liquid nitrogen or the full vitrification and thawing process. There was no decline in oocyte viability following cold shock or exposure to the vitrification and thawing media. Following the full vitrification and thawing process there was a decline in oocyte viability (chi(2)=20.0, P<0.001) but approximately 70% of oocytes remained viable. This study provides further evidence that oocyte vitrification is a promising strategy for genome resource banking in carnivorous marsupials and suggests that it should be considered in conservation plans for the survival of the iconic Tasmanian devil.