title: Non-enzymatic formation of formaldehyde in mouse oocyte freezing mixtures.
abstract: Three cryoprotectant solvents, dimethylsulphoxide, 1,2-propanediol and glycerol, were investigated for a non-enzymatic reaction product, formaldehyde. All three cryoprotectants demonstrated a direct relationship between increasing solvent molarity and increasing formaldehyde concentration which was independent of temperature and protein (bovine serum albumin). Medium composition significantly influenced the formaldehyde concentration with HTF > T6 > M16 = M2. The formaldehyde could be effectively removed by reduced glutathione, cysteine and dithiothreitol with cysteine being the most effective scavenging agent. A reaction mechanism for this scavenging is proposed. The combination of cysteine and cryoprotectant reduced the zona pellucida 'hardening' effect in mouse oocytes.
authors.affiliation: Department of Biochemistry, University of Otago, Dunedin, New Zealand.
authors.forename: G
authors.initials: G
authors.lastname: Karran
authors.forename: M
authors.initials: M
authors.lastname: Legge
mesh_terms: D000818:Animals; D015925:Cryopreservation; D003451:Cryoprotective Agents / Q000494:pharmacology*; D003470:Culture Media; D003545:Cysteine / Q000494:pharmacology; D004121:Dimethyl Sulfoxide / Q000494:pharmacology; D004229:Dithiothreitol / Q000494:pharmacology; D005260:Female; D005557:Formaldehyde / Q000032:analysis / Q000378:metabolism*; D005978:Glutathione / Q000494:pharmacology; D005990:Glycerol / Q000494:pharmacology; D051379:Mice; D009865:Oocytes / Q000187:drug effects / Q000502:physiology*; D019946:Propylene Glycol; D011409:Propylene Glycols / Q000494:pharmacology; D012710:Serum Albumin, Bovine / Q000494:pharmacology; D015044:Zona Pellucida / Q000187:drug effects / Q000502:physiology
chemical_list: D003451:Cryoprotective Agents; D003470:Culture Media; D011409:Propylene Glycols; D005557:Formaldehyde; D012710:Serum Albumin, Bovine; D019946:Propylene Glycol; D005978:Glutathione; D003545:Cysteine; D005990:Glycerol; D004229:Dithiothreitol; D004121:Dimethyl Sulfoxide