caa a22 4500 477117090 CHVBK 20180405111625.0 cr unu---uuuuu 170330e19960601xx s 000 0 eng 10.1007/BF01875570 doi (NATIONALLICENCE)springer-10.1007/BF01875570 Hazel Jeffrey Department of Zoology, LSC 226, Arizona State University, 85287-1501, Tempe, AZ, USA aut Role of molecular species catabolism in the temperature-induced restructuring of phosphatidylcholines in liver microsomes of thermally-acclimated rainbow trout ( Oncorhynchus mykiss ) [Elektronische Daten] [Jeffrey Hazel] Most previous studies of the temperature-induced restructuring of phospholipid molecular species composition have examined steps in the biosynthesis of phospholipids to explain the accumulation of unsaturated fatty acids in membranes of cold-acclimated poikilotherms. In contrast, the present study explores the role of phospholipases in this restructuring process by determining the rates of degradation of specific molecular species of phosphatidylcholine, using enzymes (microsomes) freshly isolated from the liver of rainbow trout. (Oncorhynchus mykiss) acclimated to either 5° or 20°C. The substrate preparation employed to assay phospholipase activity possessed a range of molecular species, all radiolabeled with 1-14C-palmitic acid at thesn-1 position, similar to that present in native trout liver microsomes. After defined periods of incubation (120 and 240 min at 5°C; 60 and 120 min at 20°C), phospholipids were extracted from the reaction mixture and the distribution of radioactivity among the molecular species of phosphatidylcholine was determined by HPLC/liquid scintillation counting. In general, molecular species catabolism was not significantly influenced by either assay or acclimation temperature. Only in 20°C-acclimated fish did a reduction in assay temperature (from to 20 to 5°C) result in significantly increased proportions of radioactivity being recovered in one polyunsaturated fatty acid-containing species (16:0/22:6-PC). It is concluded: 1) that phospholipase specificity, assayed under conditions approximating thosein situ, is not significantly influenced by temperature; and 2), that the increased proportions of unsaturated fatty acid-containing molecular species of phosphatidylcholine observed at low temperatures must reflect the specificity of biosynthetic rather than degradative processes. Kugler Publication, 1996 temperature acclimation nationallicence phosphatidylcholine nationallicence molecular species nationallicence catabolism nationallicence microsomes nationallicence liver nationallicence phospholipase nationallicence rainbow trout nationallicence Fish Physiology and Biochemistry Kluwer Academic Publishers 15/3(1996-06-01), 195-204 0920-1742 15:3<195 1996 15 10695 https://doi.org/10.1007/BF01875570 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF01875570 text/html Onlinezugriff via DOI NATIONALLICENCE 100 1- Hazel Jeffrey Department of Zoology, LSC 226, Arizona State University, 85287-1501, Tempe, AZ, USA aut NATIONALLICENCE 773 0- Fish Physiology and Biochemistry Kluwer Academic Publishers 15/3(1996-06-01), 195-204 0920-1742 15:3<195 1996 15 10695 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer