title: Sodium balance in eggs and dechorionated embryos of the Atlantic salmon Salmo salar L. exposed to zinc, aluminium and acid waters.
abstract: Ionic regulation of eyed eggs of Atlantic salmon was studied using intact eggs and embryos from which the chorion and perivitelline fluid had been removed, a preparation which remained in good condition for at least 2 weeks. Both intact eggs and embryos in freshwater showed similar Na+ influx rates (0.0064 and 0.01 microM g-1 hr-1, respectively) but Na+ efflux rates (0.0024 and 0.0064 microM g-1 hr-1, respectively) were greater in embryos, suggesting that the perivitelline fluid which is known to bind cations has an important function in preventing Na+ loss from the yolk and embryo. Over 90% of the egg Na+ is located in the yolk and embryo but only about 10% is exchangeable while the chorion contains about 8% Na+ which is non-exchangeable. Both eggs and embryos in acid water at pH 4, in Zn2+ 5 mM l-1 and in aluminium 1 mM l-1 showed greatly reduced Na+ uptake but eggs in 10 microM l-1 aluminium or 100 microM l-1 Zn2+ showed normal Na+ balance while embryos were normal in 10 microM l-1 aluminium but showed reduced Na+ uptake in 100 microM l-1 Zn2+. It is concluded that the chorion and perivitelline fluid have a capacity to protect the embryo from metal ions and acid water.
authors.forename: F B
authors.initials: FB
authors.lastname: Eddy
authors.forename: C
authors.initials: C
authors.lastname: Talbot
mesh_terms: D000535:Aluminum / Q000494:pharmacology*; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002823:Chorion / Q000378:metabolism; D004625:Embryo, Nonmammalian / Q000378:metabolism*; D005260:Female; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D010063:Ovum / Q000187:drug effects / Q000378:metabolism*; D012474:Salmon; D012964:Sodium / Q000378:metabolism*; D014817:Vitelline Membrane / Q000378:metabolism; D015032:Zinc / Q000494:pharmacology*
chemical_list: D012964:Sodium; D000535:Aluminum; D015032:Zinc; D002118:Calcium