The role of amides in seminal cryopreservation of wild silverside, Odontesthes bonariensis

Amides were tested as internal cryoprotectants for the preservation of wild silverside (Odontesthes bonariensis) sperm. The semen was diluted in modified Mounib's medium and cryopreserved by adding 2, 5, 8 or 11% of dimethyl acetamide (DMA), dimethyl formamide (DMF) or methyl formamide (MF). Dimethyl sulfoxide (DMSO) at a concentration of 10% diluted in modified Mounib's medium was used as a control. The rate motility (17.7 ± 1.9%) and time motility (143.2 ± 9.7 s) (P < 0.05) of the sperm were higher with 2% DMF when compared with the other treatments. Despite the better motility results obtained with 2% DMF, the solution was not able to maintain cellular structure integrity of the cryopreserved sperm. The 10% DMSO and 8% MF treatment allowed for completeness of the plasma membrane (34.8% and 29%), functional mitochondria (19.8% and 16.2%) and plasma membrane fluidity (39.4% and 46.4%); furthermore, rate motility (11.8% and 10%) and time motility (81.4 s and 71.8 s) of the sperm were found to be at suitable levels when compared with 2% DMF. Thus, our evaluation suggests that 10% DMSO and 8% MF provide better cryopreservation of O. bonariensis sperm cells.