In vitro effect of copper ions on transbilayer distribution of aminophospholipids in synaptosomal membrane of walleye pollock (Theragra chalcogramma).

Effect of copper ions on lipid matrix organization of synaptosomal membrane of the marine fish Theragra chalcogramma was investigated. It was demonstrated that interaction of copper ions with these membrane stimulated the process of lipid peroxidation and caused changes in the transbilayer distribution of aminophospholipids. Accessibility of phosphatidylethanolamine was increased more than twice, and of phosphatidylserine more than ten times, that can be explained by changes in asymmetrical structure of lipid matrix of synaptosomal membrane. We suggested, that the main mechanism of copper-stimulated damage in transbilayer organization of the membrane is oxidation of membrane protein sulfhydryl groups.

Cadmium-induced alterations in essential trace element homeostasis in the tissues of scallop Mizuhopecten yessoensis.

Studies were performed regarding the effect of cadmium accumulation on the levels of essential elements (copper, zinc and iron) in the tissues of a marine bivalve mollusc, Mizuhopecten yessoensis, exposed to cadmium at 250 ppb during 2 weeks. It was found that the concentration of cadmium in the tissues increased in the order gonads < gills < hepatopancreas < kidney during exposure time. However, the highest value of concentration factor was recorded in the gills. Our data demonstrate that cadmium accumulation in all mollusc tissues is followed by the alterations in copper, zinc and iron concentration, but that the pattern of these changes varies with each tissue. Cadmium had the most pronounced effects on essential trace element homeostasis in the kidney. The present study suggests that levels of the essential metals in a particular tissue can be modified depending on the level of cadmium accumulation. The possible mechanisms of the effects of cadmium on the essential trace elements are discussed.

[Lipid composition of mechanosensitive cell cilia and mechanoreceptor organ of bivalve molluscs]. / Osobennosti lipidnykh sostavov resnichek mekhanochuvstvitel'nykh kletok i mekhanoretseptornogo organa dvustvorchatykh molliuskov.

The lipid composition of the mechanoreceptive organ of two marine molluscs in comparison with other molluscan tissues and of isolated cilia of sense organ hair cells in comparison with the gill cilia has been studied. It was shown that the lipid composition of the mechanoreceptive organ differs in a number of features from that of other organs and that the ratios of individual phospholipid classes vary in cilia and intact organs. Ciliary aminophospholipids make up to approximately 89%, whereas choline-containing phospholipids--only 6-8% of the total phospholipid pool. No qualitative phospholipid differences between sense cell cilia and gill cilia were found. However, hair cell cilia contain less phosphatidylethanolamine and choline phospholipids, but more phosphatidylserine and phosphatidylinositol. This suggests that the observed peculiarities of hair cell cilia may play a role in the maintenance of the proper arrangement of hair bundles and the distance between the cilium and stereovilli and/or in the regulation of Ca2(+)-dependent processes.

[Mechanisms of the initiation of lipid peroxidation in the synaptosomes of marine teleosts]. / Issledovanie mekhanizmov initsiirovaniia perekisnogo okisleniia lipidov v sinaptosomakh morskikh kostistykh ryb.

The initial rates of NAD- and NADPH-dependent enzymic and Fe+-ascorbic acid-dependent nonenzymic lipid peroxidation have been measured in synaptosomes from the brain of 4 teleost species. The rates of peroxidation were compared with lipid composition and fatty acid composition of total lipids in order to reveal factors accounting for the intensity of peroxidation in the excitable membranes from the brain of ectotherms. The data obtained indicate that the rates of enzymic lipid peroxidation do not correlate with lipid and fatty acid compositions, depending on the efficiency of production of oxygen in the active form by pyridine nucleotide-dependent enzymic systems. Activation of lipid peroxidation during adaptation of animals to the environment may be considered as one of the mechanisms which account for compensatory changes in fatty acid composition of the membrane lipids.

[Is a change in the microviscosity and asymmetrical distribution of phospholipids in the membrane a necessary condition for signal transmission? A comparison of the mechanisms of signal transmission in the plasma membranes of the brain synaptosomes and retinal photoreceptor membranes]. / Iavliaetsia li izmenenie mikroviazkosti i asimmetrichnoe raspredelenie fosfolipidov v membrane obiazatel'nym usloviem peredachi signala? Sopostavlenie mekhanizmov peredachi signala v plazmaticheskikh membranakh sinaptosom mozga i fotoretseptornykh membranakh stechatki.

The localization of amino phospholipids (phosphatidyl ethanolamine, phosphatidyl serine) and their fatty acid composition in the outer and inner monolayers of plasma membranes from rat brain synaptosomes and retinal photoreceptors in the fish Theragra chalcograma have been studied by chemical modification. The mobility of the lipid components of these membranes was investigated by fluorescent and EPR spin probing techniques after transformation of outer (chemical and physical) signals. The data obtained are discussed in terms of molecular organization of the lipids and of the changes in the mobility of the lipid components of plasma membranes from brain synaptosomes and retinal photoreceptors during transmembrane transmission of the signal.

[Fatty acid composition of the bilayer phospholipids in the photoreceptor membranes and aminophospholipids from the rhodopsin microenvironment of warm-blooded and cold-blooded vertebrates]. / Zhirnokislotnyi sostav fosfolipidov bisloia fotoretseptornykh membran i aminofosfolipidov mikrookruzheniia rodopsina teplokrovnykh i kholodnokrovnykh pozvonochnykh.

Studies have been made on the distribution of phospholipids between rhodopsin and free lipids of photoreceptor membranes of the outer segments of retinal rods from cattle, frog Rana temporaria and fish Teragra chalcogramma. comparative investigation of fatty acid composition of phospholipids from rhodopsin microboundary and lipid bilayer in photoreceptor membranes was made as well. Amino phospholipids from rhodopsin microboundry were revealed using glutaraldehyde. This reagent by means of its aldehyde groups links phospholipid amino groups with amino groups of proteins of photoreceptor membranes. After this treatment, free phospholipids of lipid bilayer were extracted from photoreceptor membranes by methanol-chloroform mixture. It was demonstrated that fatty acid composition of phospholipids of lipid bilayer differs from that of amino phospholipids from rhodopsin microboundary. In the animals investigated, fatty acids of phospholipids from lipid bilayer were found to be more unsaturated than fatty acids of amino phospholipids from rhodopsin microboundary. This difference was more pronounced in photoreceptor membranes from the frog and fish than from cattle.