[A brief protocol for sperm cryopreservation and revival in zebrafish].

Zebrafish is an important vertebrate model organism for the study of embryonic development and the underlying genetic mechanism. Numerous mutants and transgenics have been generated in recent years, long-term and safe storage of these fish lines is of crucial importance for every zebrafish community/lab. Sperm cryopreservation and revival has become a preferred method for this purpose, which provides extra and reliable security as a backup for the cost-effective maintenance of genetic stocks in addition to reducing space demanding for housing large amount of live fish. This is especially critical for invaluable fish lines against accidental loss. Generally, the sperm are obtained by either squeezing the male fish or dissecting out and homogenizing the testes, then they are mixed with the freezing medium before gradually frozen as aliquots in liquid nitrogen. They can be easily revived through in vitro fertilization whenever necessary. This technique was introduced into zebrafish research three decades ago and has gradually become mature and more reliable following the im-provement of many critical factors and steps, including cryoprotectants and conditions for freezing and revival. Base on pioneers' work, our lab has established and improved a simple method for sperm cryopreservation and revival which shows high recovery rate after relatively long storage time. Here we briefly summarize the history and development of the methods for sperm cryopreservation and revival in zebrafish and present a brief protocol for the practice of sperm cryopreservation and revival, which is routinely used in our lab.