title: Dietary copper deficiency alters protein and lipid composition of murine lymphocyte plasma membranes.
abstract: Protein and lipid analyses were conducted on isolated erythrocyte and lymphocyte plasma membranes from 7-wk-old male C57BL copper-deficient and copper-supplemented mice to investigate mechanisms for the altered immunity that accompanies dietary copper deficiency. Beginning at parturition, dams were fed a diet low in copper (0.5 mg/kg) and the offspring were weaned to this diet. Half the dams and their respective offspring received supplemental copper (20 mg/L) in the drinking water (+Cu) and served as controls. Unsupplemented offspring (-Cu) had lower activity of cuproenzymes serum ceruloplasmin, spleen and thymus cytochrome-c oxidase and copper, zinc-superoxide dismutase. The -Cu mice exhibited anemia, splenomegaly and thymic atrophy. Based on the marker enzyme alkaline phosphodiesterase I (APDE-I), lymphocyte plasma membranes were enriched 7- to 10-fold for spleen and thymus, respectively, after discontinuous sucrose density centrifugation. The activity of APDE-I was higher in spleen and thymus samples from -Cu mice than from those of +Cu mice for both crude homogenates and purified plasma membranes. Proteins were fractionated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis followed by silver staining. A yellow-appearing band, Mr 74,000, present in all splenic membrane samples from +Cu mice was not evident in the samples from -Cu mice. Fatty acid methyl esters (FAME) were quantified by gas chromatography. Compared to splenic membranes from +Cu mice, the samples from -Cu mice demonstrated significant changes in all FAME (lower 16:0, 18:0 and 20:3n-6 and higher 18:1n-9, 18:2n-6 and 20:4n-6), including a higher unsaturation index. FAME composition of erythrocyte ghosts from -Cu mice demonstrated similar changes.(ABSTRACT TRUNCATED AT 250 WORDS)
mesh_terms: D000818:Animals; D002458:Cell Fractionation; D002462:Cell Membrane / Q000378:metabolism; D003300:Copper / Q000008:administration & dosage / Q000172:deficiency*; D004032:Diet; D004910:Erythrocyte Membrane / Q000378:metabolism; D005227:Fatty Acids / Q000378:metabolism; D008214:Lymphocytes / Q000378:metabolism*; D008297:Male; D008563:Membrane Lipids / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D013154:Spleen / Q000166:cytology; D013950:Thymus Gland / Q000166:cytology
chemical_list: D005227:Fatty Acids; D008563:Membrane Lipids; D008565:Membrane Proteins; D003300:Copper