title: Lipid composition and microsomal ATPase activities in gills and kidneys of warm- and cold-acclimated sea bass (Dicentrarchus labrax L.).
abstract: The response to cold of gill and kidney membrane lipid composition and microsomal (Na(+)+K(+))-ATPase, Na(+)-ATPase and Mg(2+)-ATPase activities in reared sea bass (Dicentrarchus labrax L.) was investigated. Fish acclimation was carried out according to the seasonal cycle from August to March. No cold-promoted increase in fatty acid unsaturation was shown in gill and kidney polar lipids and in total lipids of mitochondria and microsomes. In both tissues the (Na(+)+K(+))-ATPase exhibited positive compensation for cold acclimation whereas the Na(+)-ATPase displayed negative compensation. The Mg(2+)-ATPase showed no compensation in the gills and positive compensation in the kidneys. During cold acclimation the break in the Arrhenius plot of the (Na(+)+K(+))-ATPase decreased, whereas breaks of both the Na(+)-ATPase and the Mg(2+)-ATPase activities remained unchanged. The results indicate that the sea bass does not adopt membrane unsaturation as a cold-facing strategy. The cold-promoted enhancement of (Na(+)+K(+))-ATPase activity in osmoregulatory tissues may be advantageous to maintain efficient osmoregulation under thermodynamically unfavourable conditions.
authors.affiliation: Dipartimento di Biochimica "G. Moruzzi" , Sezioni di Biochimica Veterinaria, Università di Bologna, Via Tolara di Sopra, 50, 40067, Ozzano Emilia(BO), Italy.
authors.forename: V
authors.initials: V
authors.lastname: Ventrella
authors.forename: A
authors.initials: A
authors.lastname: Pagliarani
authors.forename: M
authors.initials: M
authors.lastname: Pirini
authors.forename: G
authors.initials: G
authors.lastname: Trigari
authors.forename: F
authors.initials: F
authors.lastname: Trombetti
authors.forename: A R
authors.initials: AR
authors.lastname: Borgatti