Effect of zinc on carp (Cyprinus carpio L.) erythrocytes.

The effect of zinc exposure on some properties of the carp erythrocyte membrane was studied in vitro. Red blood cells plasma membranes were separated from other cellular membranes using a combination of differential and density gradient centrifugation. The purity of obtained plasma membrane preparations was determined by measuring the activity of the marker enzymes. Electrophoretic patterns of the main erythrocyte membrane proteins excluded their degradation during the isolation and purification procedure. Carp erythrocyte membranes, obtained from cells previously incubated with increasing ZnSO4 concentrations, were used to elucidate the effect of zinc ions on their physical and biochemical properties. Using fluorescent probes: 12-AS and TMA-DPH, we found that zinc ions reduced the fluidity of the lipid bilayer, both in the middle and near the aqueous interface. Moreover, it was observed that zinc had no significant influence neither on the Na,K-ATPase activity nor on the thiol groups content in the erythrocyte membrane. We also detected that incubation of erythrocytes with zinc lead to the marked decrease of hemolytic resistance of the cells. Our studies demonstrate that zinc at higher concentrations may be toxic to carp erythrocytes causing changes in the membrane fluidity and hemolytic resistance.

Zinc-induced damage to carp (Cyprinus carpio L.) erythrocytes in vitro.

Fish erythrocytes were used to elucidate the effect of zinc ions on the cell antioxidant defence system. It was detected that an increase of the Zn2+ concentration (0.01-1 mM) leads to a marked decrease (p < 0.05) in the catalase and the glutathione peroxidase activities. We observed a loss of 14-39% activity of glutathione peroxidase, and 16-20% diminution for catalase. No significant changes were found in case of the superoxide dismutase. Incubation of red blood cells with zinc brought about a decrease of the erythrocyte thiol group content. Treatment of carp erythrocytes with zinc ions also resulted in enhanced hemolysis and in the induction of significant (p < 0.001) changes in the intracellular glucose level. The increase of glucose concentration in the erythrocytes was correlated with increased concentration of metal in the incubation medium. It was proposed that Zn could affect transport systems across the red blood cells and therefore increased the permeability of the membranes to small molecules (e.g. hexose), and led to hemolysis. Zinc ions could act as a potential cell toxicant, leading to disturbances in functions of the antioxidant defence system and to alterations in the erythrocyte membrane properties.

Haemocyanin of some Oniscidea.

In the haemolymph of Oniscidea haemocyanin exists mainly in the form of hexamer 16S (90%); the 5S and 24S components are present in small amounts. Alkaline dissociation of the examined 16S haemocyanins is dependent on pH and divalent cations (Ca2+,Mg2+). The 16S component consists of 23-24.5% acidic amino acids, 15-18% basic amino acids and small quantities of tryptophan and cysteine.

Cystic fibrosis: II. Altered microviscosity of erythrocyte membrane.

Erythrocyte membrane fluidity alterations in cystic fibrosis are described. The relative flexibility of the membrane was studied using lipid spin label, i.e. methyl-5-doxylpalmitate (M5DP), and pyrene as a fluorescence probe. It was found that there was a decrease of membrane fluidity in the hydrophobic midzone of the membrane, probed by pyrene, as well as at the hydrophilic surface region, probed by M5DP.

Aged erythrocytes exhibit decreased anion exchange.

The rate of transport of [32P] phosphate into human and bovine erythrocytes and of a spin-label analogue of phosphate (Tempo-phosphate) into human erythrocytes was found to decrease with increasing erythrocyte age by 15-20% when comparing 20% most dense cells with 20% of lightest cells. The activation energy of Tempo-phosphate transport did not show significant changes upon erythrocyte aging.

Phosphorus fractions of crayfish haemolymph, serum and haemocyanin.

Different amounts of haemolymph proteins participate in clot formation in Astacus leptodactylus and Orconectes limosus (20% and 10%, respectively), although in both species the content of proteins in haemolymph is similar. In both species the content of total phosphorus in the clot was similar (0.33-0.49%, w/w) but it was about 6 times lower in serum of O. limosus than in serum of A. leptodactylus (2.2 and 14.8 mg/100 ml, respectively). An even greater difference in phosphorus content was found in the protein precipitated from serum. In both species lipid phosphorus was predominant (77% of total haemolymph phosphorus in A. leptodactylus and 52% in O. limosus). Phospholipids were found mainly in serum. Only traces of phosphorus (0.005%) and small amounts of fatty acids were found in purified haemocyanin preparations.

Aging of the erythrocyte. III. Cation content.

Studies on the main cation content of density-separated bovine erythrocytes showed a progressive decrease in the levels of K+ and Mg2+ with increasing cell density (and age) accompanied by an increase in the level of Na+. The magnitude of net cation loss corresponded to that of red cell volume decrease, but could not account for the total increase in the microviscosity of the erythrocyte interior.

The level of free amino acids in erythrocytes of different breeds of hen.

The content of free amino acids was determined in erythrocytes of adult 'Leghorn' (Lg, 'White Rock' (WR) and 'Cornish' (Cr) hens, bred under identical conditions. The concentration of total amino acids was twice as high in the erythrocytes as in plasma, amounting to 396 µm/100 ml, 424 µm/100 ml and 475µm/100 ml in 'White Rock', 'Cornish' and 'Leghorn' hens, respectively.Significant differences were found in the ratio of basic amino acids to acidic amino acids. These values were 0.76, 1.75 and 3.19 in 'White Rick', 'Leghorn' and 'Cornish' hens, respectively; in the plasma of all 3 breeds the ratio was 1. Statistically significant interbreed differences were expressed more distinctly in erythrocyte than in plasma amino acid concentrations. For absolute concentrations the differences were significant in the case of 9 amino acids.

Effect of starvation on the content of free amino acids in plasma of different breeds of hen.

'Leghorn', 'Cornish' and 'White Rock' hens were subjected to starvation. Free amino acids were determined in blood samples taken after 48, 72 and 96 h of starvation. A progressive decrease in concentration of the majority of amino acids was found. Changes in amino acid concentrations during starvation were dependent on the breed of hen.

The content of free amino acids in plasma of hens of different strains.

Free amino acids were estimated in the plasma of Leghorn, Cornish and White Rock hens, bred under identical conditions. It was found that the plasma of Leghorn hens had a lower content of amino acids. The differences were especially pronounced for proline, glutamic acid and glycine. It was established that a lower percentage of valine, leucine and isoleucine was typical of Leghorn hens in comparison with Cornish hens. The obtained results indicate that the level of free amino acids in blood plasma is genetically controlled.

Oxygen affinity of red cells hemolysates of different hen breeds.

Oxygen affinity and number of -SH groups of hemoglobins have rather constant values for hens belonging to Leghorn, Whiterock, Rhode Island Red, Sussex and Cornish breeds, and for hybrids between Rhode Island Red and Leghorn, irrespective of the breed. Number of -SH groups in red cell hemolysates amounts to 8 per mole Hb (7,88 - 8,48) , logp50=1,04-0,94; value of "n" for Leghorns is 1,70, for Whiterocks 2,80.