title: Successful fertility experiments with cryopreserved spermatozoa of barramundi, Lates calcarifer (Bloch), using dimethylsulfoxide and glycerol as cryoprotectants.
abstract: The fertility of cryopreserved Lates calcarifer sperm was studied to increase the availability of semen for routine fertilization of stripped eggs and to provide a tool for selective breeding. Semen diluted (1:4 v/v) and frozen (-196 degrees C) with 5% dimethylsulfoxide (DMSO) or 10% glycerol (final concentration) as cryoprotectants was used to inseminate freshly stripped ova. Frozen-thawed sperm were motile for about 4 min after being mixed with seawater. In the DMSO medium, post-thaw sperm activation was immediate after dilution with seawater, but in the glycerol medium maximum motility intensity was delayed for up to 1 min. When eggs and sperm were mixed before the addition of seawater, semen frozen with DMSO as cryoprotectant gave a mean hatch rate (84.1%) no different (P > 0.05) from that of unfrozen semen diluted with Ringer's solution (80.7%) or with DMSO (83.7%), but higher (P < 0.05) than that of semen frozen with glycerol (60.9%). Adding sperm to seawater 30 s before mixing with eggs did not improve the fertility of sperm cryopreserved with glycerol. Eggs inseminated with glycerol-cryoprotected sperm showed higher mortality during incubation than those inseminated with DMSO-cryoprotected sperm. Sperm held in liquid nitrogen for 90 days with DMSO as cryoprotectant yielded acceptable fertilization and hatching rates with semen-to-ova ratios of up to 1:100 (v/v) , and produced fish with no apparent abnormalities over a 29-day period after hatch. These results show that cryopreservation of L. calcarifer sperm is feasible and well suited to a variety of hatchery purposes.
authors.affiliation: Queensland Department of Primary Industries, Southern Fisheries Centre, Deception Bay, Australia.
authors.forename: P J
authors.initials: PJ
authors.lastname: Palmer
authors.forename: A W
authors.initials: AW
authors.lastname: Blackshaw
authors.forename: R N
authors.initials: RN
authors.lastname: Garrett
mesh_terms: D000818:Animals; D001492:Bass / Q000196:embryology / Q000502:physiology*; D015925:Cryopreservation; D004121:Dimethyl Sulfoxide / Q000494:pharmacology*; D005260:Female; D005306:Fertilization; D005990:Glycerol / Q000494:pharmacology*; D008297:Male; D009584:Nitrogen; D013081:Sperm Motility; D013094:Spermatozoa / Q000502:physiology*
chemical_list: D009584:Nitrogen; D005990:Glycerol; D004121:Dimethyl Sulfoxide