Freezing tolerance in embryos and spermatozoa of the sea urchin

Male chromosomes of sea urchin hybrid andromerogones created with cryopreserved sperm

“…2) Sperm viability after freezing and thawing should strongly affect cleavage rate. When whole eggs were inseminated with cryopreserved same-species sperm, fertilization rates varied from 5% to 95% (Dunn and McLachlan, 1973), 6% to 78% (Asahina and Takahashi, 1978), and 0% to 74.3% (Kurokura et al, 1989). In the present study, cleavage rates varied widely in the case of H. pulcherrimus nonnucleate egg fragments inseminated with cryopreserved same-species sperm (Table 1), which may indicate the possibility of wider variation in the case of the non-nucleate fragments with heterospermic insemination.…”

“…We can obtain sperm more easily than eggs in sea urchins because the male breeding season is longer than the female one. Moreover, sea urchin sperm can be cryopreserved (Dunn and McLachlan , 1973;Asahina and Takahashi, 1978;Kurokura et al ., 1989), which facilitates the creation of hybrid andromerogones, and clear metaphase plates of male chromosomes may be obtained from hybrid andromerogones for many species.…”

Freezing tolerance of sea urchin embryonic cells: Differentiation commitment and cytoskeletal disturbances in culture

“…In contrast, 10% survival was reported in fertilized eggs [8]. Numerous developmental anomalies were revealed in sea urchin embryos after freezing at http://dx.doi.org/10.1016/j.cryobiol.2015.06.002 0011-2240/Ó 2015 Elsevier Inc. All rights reserved.…”

“…As shown previously, the effect of many cryoprotectants can vary according to the developmental stage [3,8,19,24,58]. High concentrations of cryoprotectants have the most pronounced lethal effect on unfertilized eggs and zygotes from sea urchins [8].…”

“…However, due to many factors, some disturbances occur in living cells after freezing-thawing. The traditional penetrating cryoprotectants that are used for freezing mammalian cells, such as dimethyl sulfoxide (Me 2 SO) and ethylene glycol (EG), are more toxic for cells from aquatic animals [3,8,16,24,49,58]. Several factors can reduce the toxicity of penetrating cryoprotectants: using lower temperatures during the initial steps of cryopreservation and the addition of non-penetrating cryoprotectants, that have the properties of an osmotic buffer, such as trehalose or polyvinylpyrrolidone [1,11,45,our data].…”