보관 방법에 따른 Rotifer Brachionus plicatilis 내구란의 부화

Abstract

The rotifer Brachionus plicatilis is one of the most important food organisms in aquaculture. The resting eggs pro-duced by mictic female rotifers are easily stored and hatched, making them useful as the starter for the mass culture of rotifers in marine larval culture. This study examined the optimum preservation method for resting eggs to ensure a high hatching rate. To produce resting eggs, the marine rotifer B. plicatilis was cultured with Nannochloris oculata (KMMCC 16). The resting eggs were harvested and cryopreserved using 5% and 10% methanol (MeOH), dimeth-ylsulfoxide (DMSO), and glycerol as cryoprotectant agents (CPAs). The cryopreservation comprised slow or rapid freezing and the resting eggs were stored for one month in liquid nitrogen (-196˚C). The resting eggs were also dried at different temperatures (30, 40, and 50˚C) and for different times (1, 2, and 3 h). In general, the hatching rates of the resting eggs preserved with CPA were higher than those without CPA and the slow freezing method was better than the rapid freezing method. However, the optimum CPA concentration for the hatching rate of the resting eggs varied with the freezing method and kind of CPA, and the CPA also affected the viability of the resting eggs. Dried resting eggs had a high, rapid hatching rate over 80%. The moisture content of the resting eggs cryopreserved in liquid nitro-gen affected the hatching rate. Drying at 30˚C for 1 hour resulted in a high hatching rate of the resting eggs. In con-clusion, drying at 30˚C for 1 hour and preservation in liquid nitrogen with the slow freezing method, without CPA, is recommended for a high hatching rate (ca. 95%) of rotifer resting eggs.Key words:Brachionus plicatilis, Cryopreservation, Dry, Hatching rate, Resting eggs