Study of pufferfish (Takifugu niphobles) sperm: Development of methods for short-term storage, effects of different activation media and role of intracellular changes in Ca2+ and K+ in the initiation of sperm motility

The first goal of this study was the development of a short-term storage method for pufferfish (Takifugu niphobles) sperm. In this respect, the best results were obtained by diluting the sperm in a seminal-like solution and keeping it in a Petri dish in chilled storage (4°C). This method was successful in preserving sperm quality parameters without resulting in differences in fresh sperm for a relatively long-term period (7days), for use in aquaculture matters. The addition of bovine serum albumin (BSA) to the medium did not improve the results. On the other hand, both the osmolality and the ion composition of the media are essential factors which can modulate the sperm motility parameters. The osmolality of the activating medium was the most important factor in triggering pufferfish sperm motility, and osmolalities of 750–825mOsm/kg were necessary to initiate this process, demonstrating that it appears to be a dose-independent mechanism. Regarding the ion composition of the activation media, this study has shown that despite the spermatozoa being able to initiate movement without any ion in the activation medium, the absence of ions can negatively affect the kinetic parameters of the spermatozoa. Finally, in natural conditions (seawater), the activation of sperm motility generates intracellular increases in Ca2+ and K+, suggesting that these ions play an essential role in the activation mechanism of pufferfish sperm. •A short-term (7days) sperm storage method for pufferfish was developed.•Activating medium osmolality was the most important factor to trigger sperm motility.•Spermatozoa can initiate the movement without any ion in the activation medium.•Ion absence can affect negatively the spermatozoa kinetic parameters.•The activation of sperm motility generates intracellular Ca2+ and K+ increases.