title: Factors affecting the uptake of DMSO by the eggs and embryos of medaka, Oryzias latipes.
abstract: High performance liquid chromatography (HPLC) was used to assess the uptake dynamics of the cryoprotectant DMSO by intact unfertilized eggs (stage 0), 8-cell (stage 5) and eyed embryos (stage 30) of medaka, Oryzias latipes, the relation of the internal concentration (Cin) of DMSO with fertilization and survival rates, and the effects of several factors on these processes. The factors examined were: cryoprotectant concentration (0.6, 1.2, 1.9 and 2.5 M), impregnation time (1, 3, 5, 10, 15 and 20 min), temperature (0, 5 and 20 degrees C), hydrostatic pressure (0 and 50 atm), and the osmotic conditions of the materials (normal or partially dehydrated). Cryoprotectant permeation, estimated from the initial rates of DMSO uptake, was higher in embryos than in eggs and increased with embryonic development; however, the DMSO Cin in eyed embryos reached a plateau at 1-5 min and could not be increased by prolonging impregnation. The highest fertilization and survival rates for any given DMSO Cin were obtained with high concentrations and short times of impregnation rather than low concentrations and long impregnation times. Application of hydrostatic pressure (50 atm) and exposure for 3 min to a 1 M trehalose solution prior to impregnation induced a substantial increase in the DMSO Cin of 8-cell embryos in comparison to untreated controls with no significant effect on survival. Hydrostatic pressure also promoted DMSO uptake in unfertilized eggs, but with rapid loss of viability, and was ineffective in eyed embryos. The uptake of DMSO and its toxicity to 8-cell embryos were directly proportional to the temperature of impregnation. The results of this study reveal important interactions between cryoprotectant concentration, impregnation time and the developmental stage (or type) of the materials and provide evidence that hydrostatic pressure, temperature of impregnation and the osmotic conditions of the materials can be manipulated to increase the uptake of cryoprotectant by fish eggs and embryos.
authors.affiliation: Department of Food Science and Technology, Tokyo University of Fisheries, Japan.
authors.forename: Padmanav
authors.initials: P
authors.lastname: Routray
authors.forename: Toru
authors.initials: T
authors.lastname: Suzuki
authors.forename: Carlos Augusto
authors.initials: CA
authors.lastname: Strüssmann
authors.forename: Rikuo
authors.initials: R
authors.lastname: Takai
mesh_terms: D000818:Animals; D015925:Cryopreservation / Q000379:methods / Q000662:veterinary*; D003451:Cryoprotective Agents / Q000494:pharmacology*; D004121:Dimethyl Sulfoxide / Q000493:pharmacokinetics*; D004625:Embryo, Nonmammalian / Q000378:metabolism*; D005260:Female; D005306:Fertilization; D006874:Hydrostatic Pressure; D008297:Male; D009990:Oryzias / Q000196:embryology* / Q000378:metabolism; D009997:Osmotic Pressure; D010063:Ovum / Q000378:metabolism / Q000502:physiology*; D013696:Temperature; D013997:Time Factors
chemical_list: D003451:Cryoprotective Agents; D004121:Dimethyl Sulfoxide