title: Successful fertilization of Varicorhinus macrolepis eggs with sperm subjected to two freeze-thaw cycles.
abstract: Although sperm from several fish species have been successfully cryopreserved, few studies have been done in small and/or endangered species. The aim of the present work was to develop a method of freezing and refreezing Varicorhinus macrolepis semen in 1.8 mL cryovials. The effect of extenders and cryoprotectants on the motility of post-thaw sperm was examined. The motility of frozen-thawed sperm in extender D-15 was higher than that in MPRS and fish Ringer solution (P<0.05). Dimethyl sulfoxide (DMSO) and glycerol provided greater protection to sperm than methanol during freezing and thawing; the most effective concentration of DMSO and glycerol was 10%. The fertilization rate of frozen-thawed sperm was not significantly different from that of fresh sperm. Furthermore, mean (+/-S.D.) hatching rate did not differ significantly between frozen-thawed (82.7+/-12.4%) and fresh sperm (90.7+/-4.5%). Although frozen-thawed sperm that was immediately refrozen had 0% post-thaw motility, frozen semen that was refrozen after dilution with D-15 (containing DMSO at a ratio of 1:2) had post-thaw motility of 38.3+/-2.9%. Motility was lower for refrozen than for frozen sperm (P<0.05). Furthermore, fertilization and hatching rates of refrozen sperm were 42.9+/-6.7 and 34.1+/-10.5%, respectively, which were lower than that of fresh sperm (P<0.05).
authors.affiliation: Shandong Agricultural University, Daizong Street 61, Taian, 271018, China.
authors.forename: X S
authors.initials: XS
authors.lastname: Ji
authors.forename: Y
authors.initials: Y
authors.lastname: Zhao
authors.forename: S L
authors.initials: SL
authors.lastname: Chen
authors.forename: Y L
authors.initials: YL
authors.lastname: Jiang
authors.forename: H
authors.initials: H
authors.lastname: Wang
authors.forename: J Y
authors.initials: JY
authors.lastname: Song
authors.forename: L
authors.initials: L
authors.lastname: Ding
authors.forename: H J
authors.initials: HJ
authors.lastname: Chen
mesh_terms: D000818:Animals; D015925:Cryopreservation; D003451:Cryoprotective Agents / Q000494:pharmacology; D003530:Cyprinidae / Q000502:physiology*; D004531:Eggs; D005260:Female; D005306:Fertilization / Q000187:drug effects / Q000502:physiology*; D005615:Freezing; D008297:Male; D012662:Semen Preservation / Q000009:adverse effects; D013081:Sperm Motility / Q000187:drug effects; D013094:Spermatozoa / Q000166:cytology / Q000502:physiology*
chemical_list: D003451:Cryoprotective Agents