Abstract:
Considering worldwide amphibian population decline, sperm cryopreservation should be a priorityfor conservation of species in areas of high biodiversity, such as the Neotropics. In this study, we presentthe results of two cryopreservation experiments involving Rhinella marina sperm. Freezing was performedin a -80 °C freezer and dimethyl sulfoxide (DMSO) was used as cryoprotective agent. In the first experiment,the effects of 5%, 10%, and 15% DMSO were evaluated in sperm lysis and fertilization capacity. Samples wereincubated for 10 minutes at 4°C before freezing. For thawing, two procedures were tested: 21 °C thawing to beused immediately and 4 °C thawing, to be used two hours later in in vitro fertilizations. The best treatment was10% DMSO plus thawing at 4 °C, that achieved 20% successful fertilizations. In the second experiment, twosolutions were tested: 10% DMSO with and without HEPES. Freezing and post-thawing in vitro fertilizations wereperformed after a two hour incubation period at 4 °C. A considerable improvement in fertilization percentageswas obtained in this experiment, with a 75% for DMSO alone, and a 70% for DMSO + HEPES. These resultsprovide good perspectives for future implementation of sperm cryopreservation in Neotropical institutions forlocal threatened species.