Vincenzo D'Amelio

Effects of supplemental dietary carnitine on growth and lipid metabolism of hatchery-reared sea bass (Dicentrarchus labrax L.)

Abstract The diet of cultured sea bass ( Dicentrarchus labrax ) was supplemented with carnitine, in order to determine the effect of this substance on growth and metabolism. During the treatment it was evident that L-carnitine has a positive effect on the growth rate and reduces the lipid content of tissues. The dextrorotatory isomer, which antagonizes L-carnitine, has an opposite effect. The role of carnitine in lipid metabolism of cultured fish and the effect of its administration are discussed, with consideration of its possible utilization for the improvement of culture technology in aquaculture.

Carnitine administration to sea bass (Dicentrarchus labrax (L.)) during feeding on a fat diet: Modification of plasma lipid levels and lipoprotein pattern

Abstract Feeding cultured fish on a fat diet induces a modification of their lipid metabolism, increases plasma lipid content and modifies the lipoprotein electrophoretic pattern. Carnitine treatment of sea bass fed a high-fat diet reduces the circulating lipids and ameliorates the impairment of lipoprotein pattern induced by high dietary fat levels.

PHYSICOCHEMICAL AND FUNCTIONAL PROPERTIES OF PERINEREIS-CULTRIFERA (GRUBE) ERYTHROCRUORIN

Perinereis erythrocruorin has the following physicochemical properties: So20,w = 55S, corresponding to a molecular weight around 2.7-10(6); minimum molecular weight (on the basis of the heme content) 23 700 +/- 500; isoelectric point 5.1; alpha-helix content approximately 40%. At alkaline pH values in the oxygenated form the 55-S molecules dissociate into subunits with a weight average sedimentation coefficient of 3S, corresponding to a molecular weight approximately 35 000. Deoxygenation of partially dissociated samples promotes association of the 3-S subunits into a 9S component. The functional properties of Perinereis erythrocruorin are characterized by a low cooperativity in oxygen binding (n 1/2 = 1.5) at neutral pH. Cooperativity increases reversibly towards both the acid and alkaline pH range, irrespective of changes in molecular weight. This finding, taken together with the ultracentrifuge results, suggests that a subunit may represent the functional unit of the protein. The pH dependence of the oxygen affinity can be accounted for in terms of a single oxygen linked group with a pK of 8.

Lipid and apolipoprotein composition of lipoproteins of European sea bass (Dicentrarchus labrax L.)

Abstract Four lipoprotein fractions separated from Dicentrarchus labrax serum by density gradient and gel filtration chromatography show a direct relationship between molecular weight and lipid/protein ratio. Heavier molecules show a higher triglyceride content, whereas phospholipids are the main lipid class in the fraction with the lower molecular weight. A particularly complex apolipoprotein pattern is demonstrated in the isolated lipoproteins of D. labrax , characterised by an high number of apolipoproteins, varying from 19 in low-density lipoproteins (I.DL) to 15 in high-density lipoproteins (HDL). Apolipoproteins with high molecular weight (from 263,000 to 216,000 Da), considered apo-B-like, are present in low-density lipoproteins, very-low-density lipoproteins and intermediate high-density lipoproteins. The most abundant apolipoproteins, present in HDL, are considered apo-AI-like (27,000 Da) and Apo-AII-like (12,000 Da).

Fish plasma lipoproteins-comparative observations in serranides and sparides

1. Diet, time from last feeding, temperature, season and sexual stage are some of the factors influencing the lipoprotein pattern. 2. Keeping these factors constant species-specific differences observed among lipoprotein patterns of Sparus aurata, Puntazzo puntazzo, Diplodus sargus, Diplodus vulgaris and Dicentrarchus labrax are discussed. 3. Feeding habits and therefore lipid absorption and the rate of lipoprotein maturation process are the factors determining the observed differences.

Preliminary study on the effect of short-term carnitine treatment on nucleic acids and protein metabolism in sea bass (Dicentrarchus labrax L.) fry

Abstract We used labelled precursors to verify our previous hypothesis on the effects of carnitine administration on metabolism in sea bass fry. Carnitine treatment significantly enhances the rate of leucine incorporation in sea bass fry. A slight effect is observable in the incorporation rate of 3 H-uridine whereas no effect is demonstrable in the incorporation rate of 3 H-thymidine.

Serum lipoproteins of sea bass (Dicentrarchus labrax L.) purification, and partial characterization by density gradient ultracentrifugation and agarose column chromatography

Abstract 1. 1. Five classes of sea bass serum lipoproteins were purified by single vertical spin ultracentrifugation and agarose column chromatography 2. 2. VLDL, beta migrating, are the larger and less dense lipoproteins. 3. 3. LDL are the more heterogeneous in size, ranging from 11 × 10 6 to 1 × 10 6 . 4. 4. HDL represent the predominant class which, on the basis of density and electrophoresis migration, is differentiated in three subclasses. 5. 5. VHDL float at a density > 1.22 mg/ml, which corresponds to the density of the other serum lipoproteins. This subclass, with an apparent molecular weight of 1.5 × 10 5 , resembles the albumin-like fatty acids binding proteins, shown in mammals and teleosts and absent in elasmobranchs.

Ontogenetic variations of some enzymes in dicentrarchus labrax (Serranidae)

Abstract The ontogenesis of isozyme patterns of alcohol dehydrogenase (ADH), glycerol‐3‐phosphate dehydrogenase (α‐GPDH), lactate dehydrogenase (LDH), malate dehydrogenase (MDH), glucose‐6‐phosphate dehydrogenase (G‐6‐PD) and glucosephosphate isomer‐ase (GPI) in Dicentrarchus labrax was studied. ADH is active only in the liver of the adult; a‐GPDH is active in only two tissues in the adult: the A2 isozyme in white skeletal muscle and the B2 isozyme in the liver. Differential gene expression was found only for LDH, MDH and GPI, which have polymeric structure. The LDH, MDH and GPI isozymes 30 days after hatching were completely active and showed patterns very similar to those of the adult. Spatial and diachronic variations were related to genetic regulation of expression. Tissue specificity and time of expression during development represent tests of cellular differentiation.

Erythrocruorin subunits of Perinereis cultrifera Grube (Annelida, Polychaeta) compared with other erythrocruorins

Abstract Polyacrylamide gel electrophoresis (PAGE) in sodium dodecyl sulphate (SDS) shows that Perinereis cultrifera Grube erythrocruorin dissociates into five components with relative mass (Mr) of 13 300, 15 000, 54 000, 61 000, 65 000. The presence of 2-mercaptoethanol in SDS PAGE induces further dissociation: the component with Mr 54 000 gives rise to a new small subunit with M, of 16 200, while the 61000 and 65 000 components dissociate into subunits with Mr of 33 500 and 37 000, respectively. Urea PAGE of the erythrocruorin results in the separation of five bands: the cathodic bands with the highest mobilities correspond to the 16 200, 15 000 and 13 300 subunits, respectively. The erythrocruorin dissociated at alkaline pH, and subjected to SDS PAGE in the presence of 2-mercaptoethanol, dissociates completely into low molecular mass subunits. Amino end group analysis of the erythrocruorin indicates the presence of arginine, lysine, aspartic and glutamic acids. The amino acid composition shows a high c...

I pigmenti respiratori degli Anellidi Policheti

Abstract The respiratory pigmentes of Polychaetes are erythrocruorins, chlorocruorins, and hemoerythrins; only erythrocruorins (Hbs) are considered here. 1) There are extra- and intracellular Hbs, sometimes occurring together in the same species. Extracellular Hbs have a molecular weight of 3 × 106 daltons, intracellular Hbs weigh from 18000 to 36000 daltons. The extracellular Hbs owing to their high m.w. have high O2-rbinding capacity and yet contribute slightly to the osmotic pressure. The presence of intracellular Hb has been made possible by the evolution, in the erythrocyte, of a cell membrane with an high specific permeability for Cl- and HCO3- and for the presence of the enzyme carbonic anhydrase. The extracellular Hbs are structurally all very alike, being composed of several subunits arranged in a double exagon as it appears at the electron microscope analysis. They all dissociate at alcaline pH, giving rise to subunits which cannot reconstitute the native molecule. Different globins may be obser...