Ceroid lipofuscinosis in sheep. II. The major component of the lipopigment in liver, kidney, pancreas, and brain is low molecular weight protein

Previous studies on the lipopigment from the livers of sheep affected with ceroid lipofuscinosis showed that the disease does not involve a defect in lipid metabolism or abnormal lipid peroxidation and that most of the lipopigment was proteinaceous. In this study, lipopigment was isolated from liver, kidney, pancreas, and brain of affected sheep without the use of proteolytic enzymes. Lipopigment from all tissues was two-thirds protein. Modified silver staining after sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed a major band of Mr = 14,800, heterogeneous material between Mr = 5,000 and 9,000, and a major band of Mr = 3,500. These compounds did not stain for RNA or carbohydrate and were digested by a nuclease-free protease as expected for protein. They are not normal lysosomal proteins. Lipopigment levels of dolichol, ubiquinone, and cholesterol were consistent with the lipopigment being protein-enriched lysosome-derived cytosomes. The presence of the Mr = 3,500 proteins in whole affected tissue homogenates distinguished them from homogenates of normal tissues. It was concluded that low Mr proteins are specifically stored in ovine ceroid lipofuscinosis and that the ceroid lipofuscinoses may result from inherited defects in lysosomal protein catabolism.     

Ovine ceroid lipofuscinosis. The major lipopigment protein and the lipid-binding subunit of mitochondrial ATP synthase have the same NH2-terminal sequence

Previous studies on lipopigment isolated from sheep affected with ceroid lipofuscinosis (Batten's disease) showed that the disease is a lysosomal proteinosis, involving specific storage of peptide(s) that migrate in dodecyl sulfate-polyacrylamide gel electrophoresis with an apparent Mr of 3500. This band is the dominant contributor to the lipopigment mass. When purified total lipopigment proteins were loaded onto a protein sequencer, a dominant sequence was found, identical to the NH2 terminus of the lipid-binding subunit of protein translocating mitochondrial ATP synthase. This sequence was determined to 40 residues and a minimum estimate of 40% made for its contribution to the lipopigment protein mass. The full lipid-binding subunit has physical and chemical properties similar to those of the specifically stored low Mr peptide, which may be the full protein or a large NH2-terminal fragment of it. Lipopigments in the human ceroid lipofuscinoses also contain a major component with similar physical and chemical properties. These and previous results indicate that the genetic lesion in ovine ceroid lipofuscinosis causes an abnormal accumulation of this peptide in lysosomes, i.e. the disease is a proteolipid proteinosis, specifically a lysosomal mitochondrial ATP synthase lipid-binding subunit proteinosis. The analogous human diseases are likely to reflect storage of the same or similar peptides.     

Fatty acid composition and lipid peroxidation of soft-shelled turtle, Pelodiscus sinensis, fed different dietary lipid sources

Juvenile soft-shelled turtles (Pelodiscus sinensis) were fed 7 diets containing 8% of lard, soybean oil, olive oil, menhaden fish oil, or mixtures of 1 to 1 ratio of fish oil and lard, soybean oil, olive oil for 10 weeks. Growth and muscle proximate compositions of the turtles were not affected by different dietary treatments (p>0.05). Fatty acid profiles in muscle polar lipids, muscle non-polar lipids, and liver polar lipids reflected the fatty acid composition of dietary lipid source. Turtles fed diets containing fish oil generally contained significantly higher (p<0.05) proportion of highly unsaturated fatty acids (HUFA) in both polar and non-polar lipids of muscle and polar fraction of liver lipids than those fed other oils. Non-polar fraction of liver lipids from all groups of turtles contained less than 1% of HUFA. All turtles contained relatively high proportions of oleic acid in their lipids regardless of the dietary lipid source. Further, lipid peroxidation in both muscle tissue and liver microsomes of turtles fed fish oil as the sole lipid source was greater (p<0.05) than those fed fish oil-free diets. Turtles fed olive oil as the sole lipid source had the lowest lipid peroxidation rate among all dietary groups. The results indicate that dietary n-3 HUFA may not be crucial for optimal growth of soft-shelled turtles although they may be used for metabolic purpose. Further, high level of dietary HUFA not only increases the HUFA content in turtle tissues, but also enhances the susceptibility of these tissues to lipid peroxidation.     

Formation of age pigment-like fluorescent substances during peroxidation of lipids in model membranes

The formation of age pigment-like fluorescent substances during the lipid peroxidation of model membranes has been studied. Ferrous ion and ascorbate-induced lipid peroxidation of liposomal membranes containing phosphatidylethanolamine led to the formation of fluorescent substances which have characteristics similar to those of compounds derived from the reaction of phosphatidylethanolamine with purified fatty acid hydroperoxides. The fluorescent substances were accumulated in liposomal membranes, whereas thiobarbituric acid-reactive substances formed during lipid preoxidation were immediately released from the liposomal membranes. The thiobarbituric acid-reactive substances free from the membranes were not reactive with amino compounds such as phosphatidylethanolamine in liposomes or glycine in aqueous phase. It was suggested that the products reacting with amino compounds are short-lived, and may be rapidly inactivated after released into aqueous phase. The formation of fluorescent products was inefficient when phosphatidylethanolamine incorporated into the liposomes insensitive to lipid preoxidation was incubated with ferrous ion and ascorbate in the presence of liposomes sensitive to the peroxidation. The results suggest that some products generated from peroxidation-sensitive lipids react with the amino group of phosphatidylethanolamine molecules which are located on the same membranes, forming fluorescent substances. The presence of phosphatidylethanolamine in the membrane suppressed the formation of thiobarbituric acid-reactive substances, suggesting that phosphatidylethanolamine may react with radicals formed and terminate the propagation.     

Importance of the polyunsaturated fatty acid to vitamin E ratio in the resistance of rat lung microsomes to lipid peroxidation

Rat lung microsomes and liposomes made from isolated lung microsomal lipids were found to be much more resistant to lipid peroxidation than those from liver in both enzymatic and nonenzymatic systems. The polyunsaturated fatty acid (PUFA) content of isolated lung microsomal lipids was 28% of total fatty acids, while liver was 54%. The vitamin E (α-tocopherol) content of isolated lung microsomal lipids was 2.13 nmol/μmol lipid phosphate and that of liver was 0.43. Individually, neither the lower PUFA content nor higher vitamin E levels could account for the resistance of lung microsomal lipids to peroxidation. Distearoyl-L-a-phosphatidylcholine and/or α-tocopherol were added to liver microsomal lipids to achieve different PUFA to vitamin E ratios at PUFA contents of 28% or 54%, and the resulting liposomes were subjected to an NADPH-dependent lipid peroxidation system utilizing cytochrome P450 reductase, EDTA-Fe⁺³, and ADP-Fe⁺³. Liposomes having PUFA to vitamin E ratios less than approximately 250 nmol PUFA/nmol vitamin E were resistant to peroxidation, whereas lipid peroxidation, as evidenced by malondialdehyde production, occurred in liposomes having higher ratios. When lipid peroxidation occurred, 40%–60% of the liposomal vitamin E was irreversibly oxidized. Irreversible oxidation did not occur in the absence of lipid peroxidation. These studies indicated that the low PUFA to vitamin E ratio in lung microsomes and isolated microsomal lipids was sufficient to account for the observed resistance to lipid peroxidation.     

Mass spectrometric analysis reveals changes in phospholipid, neutral sphingolipid and sulfatide molecular species in progressive epilepsy with mental retardation, EPMR, brain: a case study

Progressive epilepsy with mental retardation, EPMR, belongs to a group of inherited neurodegenerative disorders, the neuronal ceroid lipofuscinoses. The CLN8 gene that underlies EPMR encodes a novel transmembrane protein that localizes to the endoplasmic reticulum (ER) and ER-Golgi intermediate compartment. Recently, CLN8 was linked to a large eukaryotic protein family of TLC (TRAM, Lag1, CLN8) domain homologues with postulated functions in lipid synthesis, transport or sensing. By using liquid chromatography/mass spectrometry we analysed molecular species of major phosholipid and simple sphingolipid classes from cerebral samples of two EPMR patients representing a progressive and advanced state of the disease. The progressive state brain showed reduced levels of ceramide, galactosyl- and lactosylceramide and sulfatide as well as a decrease in long fatty acyl chain containing molecular species within these classes. Among glycerophospholipid classes, an increase in species containing polyunsaturated acyl chains was detected especially in phosphatidylserines and phosphatidylethanolamines. By contrast, saturated and monounsaturated species were overrepresented among phosphatidylserine, phosphatidylethanolamine and phosphatidylinositol classes in the advanced state sample. The observed changes in brain sphingo- and phospholipid molecular profiles may result in altered membrane stability, lipid peroxidation, vesicular trafficking or neurotransmission and thus may contribute to the progression of the molecular pathogenesis of EPMR.     

Ultrastructure and morphogenesis of ceroid pigment. II. Late changes of lysosomes in Kupffer cells of rat liver after phagocytosis of unsaturated lipids (author's transl)]

Wistar rats were injected intravenously with cod liver oil emulsion. The lipid droplets ere phagocytized by Kupffer cells and stored in lysosomes. The transformation of these lipid-containing lysosomes into ceroid pigment granules was studied electron-microscopically and cytochemically for a period of 12 weeks after the injection. The lipid droplets enclosed in lysosomes show an increasing and continous condensation from the periphery towards the center due to oxidation and polymerization of unsaturated fatty acids. During the first week almost the total amount of the stored lipids is transformed into an amorphous, highly electron-dense material which disintegrates into cloddy and globular fragments during the following time. The fragments are embedded in a fine granular, slightly electron-dense matrix showing a marked activity of acid phosphatase. The lysosomal structures which contain remnants of condensed oxidized and polymerized lipids are the electron-microscopic equivalent of the granules as seen by light microscopy. These lipids, which have been changed in their molecular structure, cannot be hydrolized by lysosomal enzymes. They remain as an indigestible material, as a waste product in lysosomal residual bodies. Both lipofuscin and ceroid are lysosomal structures containing oxidized and polymerized lipids. The differences between these lipogenous pigments are due to their different formal and causal genesis. Lipofuscin develops in parenchymal and muscle cells by autophagocytosis and by subsequent oxidation and polymerization of segregated membrane lipids. Ceroid is formed in macrophages by heterophagocytosis of unsaturated lipid material which is also oxidized and polymerized.     

The cold but not hard fats in ectotherms: consequences of lipid restructuring on susceptibility of biological membranes to peroxidation,a review

The production of reactive oxygen species is a regular feature of life in the presence of oxygen. Some reactive oxygen species possess sufficient energy to initiate lipid peroxidation in biological membranes, self-propagating reactions with the potential to damage membranes by altering their physical properties and ultimately their function. Two of the most prominent patterns of lipid restructuring in membranes of ectotherms involve contents of polyunsaturated fatty acids and ratios of the abundant phospholipids, phosphatidylcholine and phosphatidylethanolamine. Since polyunsaturated fatty acids and phosphatidylethanolamine are particularly vulnerable to oxidation, it is likely that higher contents of these lipids at low body temperature elevate the inherent susceptibility of membranes to lipid peroxidation. Although membranes from animals living at low body temperatures may be more prone to oxidation, the generation of reactive oxygen species and lipid peroxidation are sensitive to temperature. These scenarios raise the possibility that membrane susceptibility to lipid peroxidation is conserved at physiological temperatures. Reduced levels of polyunsaturated fatty acids and phosphatidylethanolamine may protect membranes at warm temperatures from deleterious oxidations when rates of reactive oxygen species production and lipid peroxidation are relatively high. At low temperatures, enhanced susceptibility may ensure sufficient lipid peroxidation for cellular processes that require lipid oxidation products.     

A histochemical and ultrastructural study of stored material in neuronal ceroid lipofuscinosis.

A histochemical and ultrastructural study of five cases of neuronal ceroid lipofuscinosis (NCL) revealed the existence of two related lipopigments differing in some tinctorial properties and ultrastructure. Type I pigment is present in all the tissues affected and corresponds to the pigmentary tertiary lysosomes of well known ultrastructure. Type II pigment occurs exclusively in the neurones of lipophilic cerebral grisea, as a component of the so called protein-myoclonic bodies. It shares with type I certain basic tinctorial properties of lipopigment and its lysosomal localization, but differs in other respects. It stains poorly if at all with the PAS and PAF techniques and is markedly metallophilic, azurophilic and positive for protein. Type II pigment is extremely electron-opaque after staining with heavy metals to the extent that they appear practically amorphous. The possibility that type II material is derived from type I pigment is considered. The amount of type II pigment is highly variable. Both types of pigments are present in residual bodies of various shape and size, including spheroids.     

Membranocystic lesion in the brain in cerebrotendinous xanthomatosis. Histochemical and ultrastructural study with evidence of its ceroid nature

A case is described of cerebrotendinous xanthomatosis with purely neurological manifestations. Cholestanol deposition in both affected and unaffected brain regions was markedly increased, reaching 18.5-20.8% of the sterol fraction. The unilateral lesions localized in the basal ganglia and cerebellar white matter featured perivascular accumulation of foam cells containing apolar lipid and ceroid. Necrosis with lipid-rich debris was a frequent finding often accompanied by prominent collagen deposition. Within these lesions there were numerous refractile thick membranes which, according to lipid histochemical techniques, could be qualified as ceroid-type lipopigment. It is suggested that the ceroid membranes arise extracellularly directly from the lipid-rich debris. Ultrastructurally, they were composed of convolutes of highly organized trilaminar membranes about 15 nm thick similar to those seen in intracellular ceroid granules. The membranes were embedded in an amorphous substance of low or medium density and were identical in their general appearance, stainability and fine structure to the membranocystic lesion in Nasu-Hakola disease and to the extracellular ceroid in atherosclerotic plaques.     

Fatty acid composition and lipid peroxidation induced by ascorbate-Fe2+ in different organs of goose (Anser anser)

Many reports have demonstrated that birds show a low degree of fatty acid unsaturation and lipid peroxidation compared with mammals of similar body size. The aim of the present study was to examine fatty acid profiles, non-enzymatic lipid peroxidation and vitamin E levels of mitochondria and microsomes obtained from liver, heart and brain of goose (Anser anser). The unsaturated fatty acid content found in mitochondria and microsomes of all tissues examined was approximately 60% with a prevalence of C18:1 n9 + C18:2 n6 = 50%. The 20:4 n6 + C22:6 n3 content was significantly higher in brain organelles (approx. 16%) compared with mitochondria and microsomes of liver and heart (approx. 4%). Whereas these organelles were not affected when subjected to lipid peroxidation, brain mitochondria were highly affected, as indicated by the increase in chemiluminescence and a considerable decrease of arachidonic and docosahexaenoic acids. These changes were not observed during lipid peroxidation of brain microsomes. Vitamin E content was higher in liver and heart than in brain mitochondria (1.77 +/- 0.06 and 1.93 +/- 0.13 vs. 0.91 +/- 0.09 nmol/mg protein). The main conclusion of this paper is that a lower degree of unsaturation of fatty acids in liver and heart mitochondria and a higher vitamin E level than in brain mitochondria protect those tissues against lipid peroxidation.     

The crystal structure of palmitoyl protein thioesterase-2 (PPT2) reveals the basis for divergent substrate specificities of the two lysosomal thioesterases,PPT1 and PPT2

Mutations in palmitoyl protein thioesterase-1 (PPT1) have been found to cause the infantile form of neuronal ceroid lipofuscinosis, which is a lysosomal storage disorder characterized by impaired degradation of fatty acid-modified proteins with accumulation of amorphous granular deposits in cortical neurons, leading to mental retardation and death. Palmitoyl protein thioesterase-2 (PPT2) is a second lysosomal hydrolase that shares a 26% identity with PPT1. A previous study had suggested that palmitoyl-CoA was the preferred substrate of PPT2. Furthermore, PPT2 did not hydrolyze palmitate from the several S-palmitoylated protein substrates. Interestingly, PPT2 deficiency in a recent transgenic mouse model is associated with a form of neuronal ceroid lipofuscinosis, suggesting that PPT1 and -2 perform non-redundant roles in lysosomal thioester catabolism. In the current paper, we present the crystal structure of PPT2 at a resolution of 2.7 A. Comparisons of the structures of PPT1 and -2 show very similar architectural features; however, conformational differences in helix alpha4 lead to a solvent-exposed lipid-binding groove in PPT1. The limited space between two parallel loops (beta3-alphaA and beta8-alphaF) located immediately above the lipid-binding groove in PPT2 restricts the binding of fatty acids with bulky head groups, and this binding groove is significantly larger in PPT1. This structural difference accounts for the ability of PPT2 to hydrolyze an unbranched structure such as palmitoyl-CoA but not palmitoylcysteine or palmitoylated proteins. Furthermore, differences in fatty acid chain length specificity of PPT1 and -2, also reported here, are explained by the structure and may provide a biochemical basis for their non-redundant roles.     

Extracellular lipids of Cladosporium (Amorphotheca) resinae grown on glucose or on n-alkanes.

Cladosporium (Amorphotheca) resinae was grown in shake culture on glucose, n-dodecane, or n-hexadecane. Growth was most rapid on glucose, and more acid accumulated in the medium than in n-alkane-grown cultures. Neutral lipid was the major lipid fraction and triglycerides were the only extracellular neutral lipids detected. Dodecanoic (lauir) acid was the predominant fatty acid (greater than 60%) in neutral lipids from all three media, with lesser amounts of tetradecanoic, hexadecanoic, and octadecanoic acids. Extracellular phospholipids identified were phosphatidylcholine, phosphatidylserine, phosphatidylethanolamine, and cardiolipin or a cardiolipin-like compound. Phospholipids from all three media contained dodecanoic acid as their principle fatty acid. Dodecanoic acid was the only extracellular free fatty acid detected. Glucose medium contained acetic, glyoxylic, and glycolic acids and an unidentified organic acid which may contribute to the lower pH in cultures after growth on glucose. In all classes of extracellular lipids the fatty acids do not correspond to the fatty acids previously determined to be associated with cellular lipids. Moreover, the fatty acids of extracellular lipids do not reflect the chain length of the n-alkane growth substrate.     

Temporal relationship of free radical-induced lipid peroxidation and loss of latent enzyme activity in highly enriched hepatic lysosomes

Loss of latency due to membrane lipid peroxidation induced in vitro was studied in highly purified rat liver lysosomes. Enriched fractions of lysosomes were isolated by free flow electrophoresis. Lipid peroxidation of lysosomes, assayed as malondialdehyde formation, was catalyzed by a radical generating system consisting of dihydroxyfumaric acid and Fe3+-ADP. The peroxidation reaction occurred readily at 37 degrees C and reached a plateau at 10 min; however, the loss of lysosomal latency, determined as increased percentage free beta-N-acetylglucosaminidase activity, occurred more gradually and reached a maximum after 30 min. Scavengers of superoxide, hydrogen peroxide, singlet oxygen, and hydroxyl radicals did not inhibit the peroxidation reaction nor prevent the loss of lysosomal latency. However, preincubation of the lysosomes with alpha-tocopherol effectively blocked the induction of peroxidation and substantially reduced the loss of lysosomal latency. These results indicate that the lysosomal membrane is susceptible to free radical-induced lipid peroxidation; further, this process may be the immediate cause of the subsequent disintegration of the lysosome. The nature of the protective effect of alpha-tocopherol is unclear but may be due to its interaction with the unsaturated membrane lipids and the subsequent interruption of the chain-reaction initiated by free radicals.     

Large Alterations in Ganglioside and Neutral Glycosphingolipid Patterns in Brains from Cases with Infantile Neuronal Ceroid Lipofuscinosis/Polyunsaturated Fatty Acid Lipidosis

Lipid composition was studied on cerebral tissue from nine children who had died of a progressive encephalopathy called the infantile form of neuronal ceroid lipofuscinosis (INCL) or polyunsaturated fatty acid lipidosis (PFAL). In the terminal stage of the disease, the concentrations of all lipid classes were found to be significantly reduced in the cerebral and cerebellar cortex and white matter. The concentration of gangliosides of the cerebral cortex was 15% and that of cerebrosides (galactosylceramide) in white matter 0.2-5% of the normal values for the children's ages. The reduction of gangliosides mainly affected those of the gangliotetraose series, particularly GD1a. The fatty acids of the linolenic acid series were strongly reduced in ethanolamine and serine phosphoglycerides. A very large increase up to 100-fold of oligoglycosphingolipids of the globo series and two fucose-containing lipids of the neolacto series was found in the forebrain of the three advanced cases examined. The brain tissue also contained very high concentrations of mono-, di-, and trisialogangliosides of the lacto and neolacto series, gangliosides with type 1 chain dominating. The structures of the gangliosides were tentatively identified by gas chromatography-mass spectrometry and monoclonal antibodies with carefully determined epitope specificity. The gangliosides and neutral glycosphingolipids had very similar fatty acid composition, consisting of about 40% stearic acid and 40% C24-acids.     

A low degree of fatty acid unsaturation leads to high resistance to lipid peroxidation in mitochondria and microsomes of different organs of quail (Coturnix coturnix japonica)

Birds – particularly long-lived species – have special adaptations for preventing tissue damage caused by reactive oxygen species. The objective of the present study was to analyse the fatty acid composition and non-enzymatic lipid peroxidation of mitochondria and microsomes obtained from liver, heart and brain of quail (Coturnix coturnix japonica), a short-lived bird. Fatty acids located in total lipids of rat liver, heart and brain mitochondria and microsomes were determined using gas chromatography and lipid peroxidation was evaluated using a chemiluminescence assay. The unsaturated fatty acid content found in mitochondria and microsomes of all tissue examined was approximately 50 and 40%, respectively with a prevalence of C18:1 n9. The C18:2 n6 content in brain mitochondria was significantly lower as compared to liver and heart mitochondria. Whereas the C20:4 n6 content in mitochondria from all tissues examined and brain microsomes was approximately 6%, liver and heart microsomes exhibited lower values. C22:6 n3 was absent in liver mitochondria, very low content in liver microsomes and heart organelles (between 0.5 and 1%) and high content in brain organelles, with mitochondria having the highest value (11%). Whereas liver and heart organelles were not affected when subjected to lipid peroxidation, brain mitochondria were highly affected, as indicated by the increase in chemiluminescence and a considerable decrease of C20:4 n6 and C22:6 n3. These results indicate that a low degree of fatty acid unsaturation in liver and heart organelles of quail, a short-lived bird, may confer advantage by decreasing their sensitivity to lipid peroxidation process.     

Thematic review series: lipid posttranslational modifications. Lysosomal metabolism of lipid-modified proteins

Much is now understood concerning the synthesis of prenylated and palmitoylated proteins, but what is known of their metabolic fate? This review details metabolic pathways for the lysosomal degradation of S-fatty acylated and prenylated proteins. Central to these pathways are two lysosomal enzymes, palmitoyl-protein thioesterase (PPT1) and prenylcysteine lyase (PCL). PPT1 is a soluble lipase that cleaves fatty acids from cysteine residues in proteins during lysosomal protein degradation. Notably, deficiency in the enzyme causes a neurodegenerative lysosomal storage disorder, infantile neuronal ceroid lipofuscinosis. PCL is a membrane-associated flavin-containing lysosomal monooxygenase that metabolizes prenylcysteine to prenyl aldehyde through a completely novel mechanism. The eventual metabolic fates of other lipidated proteins (such as glycosylphosphatidylinositol-anchored and N-myristoylated proteins) are poorly understood, suggesting directions for future research.     

Dietary lipid level influences fatty acid profiles, tissue composition, and lipid peroxidation of soft-shelled turtle, Pelodiscus sinensis

Dietary lipids containing equal portions of soybean oil and fish oil were fed to juvenile Chinese soft-shelled turtle, Pelodiscus sinensis, at supplementation level of 0 to 15% for 8 weeks. Tissue fat contents of turtles increased when dietary lipid concentration increased. Fatty acid profiles for turtles fed diets supplemented with 6% or higher levels of lipids were similar to those in dietary lipids. On absolute value basis, fatty acids of 14-, 16-, and 18-carbons in muscle of turtles fed diet without lipid supplementation were higher than those in the initial turtle muscle. Among them, C16:1 and C18:1 was approximately 4 and 2 fold higher, respectively, than that of the initial turtles. By contrast, absolute amounts of C20:5 and C22:6 in muscle of turtles fed diet without lipid supplementation were slightly less than those in the initial turtles. For turtles fed lipid supplemented diets, tissue C20:5 and C22:6, however, increased when dietary lipid level increased. These results suggest that soft-shelled turtles are capable of synthesizing fatty acids up to 18 carbons from other nutrients and that they may have limited or no ability to synthesize highly unsaturated fatty acids. Lipid peroxidation measured by thiobarbituric acid-reactive substances in tissues of turtles fed 12% and 15% lipids was greater (p<0.05) than that in turtles fed 3% to 9% lipids. This could be due to high lipid and unsaturated fatty acid content in these tissues. On lipid basis, lipid peroxidation in turtles fed diet without lipid supplementation was the highest among all groups suggesting the existence of antioxidant factors in the dietary lipids.     

The lipid composition of flight muscle mitochondria isolated from the blowfly, Phormia regina.

The role of lipids in membrane structure and function was studied by measuring the major lipid classes in mitochondria isolated from flight muscle of the blowfly, Phormia regina. Approximately 98% of the total lipid is phospholipid. Neutral lipid constitutes the remaining 2% of the total. Phosphatidylethanolamine accounts for 55–60% of the phospholipid. A molecular ratio of 4:1:1 is found for phosphatidylethanolamine, phosphatidylcholine, and cardiolipin (diphosphatidylglycerol). The neutral lipids include cholesterol, about 20%, and quinone, 40–45% of the total. The free fatty acid content of the neutral lipid fraction is variable, apparently being generated by endogenous phospholipase activity. The fatty acids of the neutral and phospholipid classes are predominantly 14–18 carbon acids; long-chain fatty acids of 20 and 22 carbons are essentially absent. The neutral lipid fraction contains 43% saturated and 51% monoenoic fatty acids. More than 65% of the phospholipid fatty acids are unsaturated. The principal fatty acids are palmitic, palmitoleic, oleic, linoleic, and linolenic. No trace of α- or β-tocopherol is detected. As vitamin E is considered an important naturally occuring antioxidant that prevents lipid peroxidation, the apparent absence of α- and β-tocopherol in these mitochondria coupled with intense oxidative activity of the mitochondria leads to the suggestion that blowfly flight muscle mitochondria may be particularly susceptible to peroxidative damage.     

Lipid fluorophores of the crystalline lens in cataracts

Microcolumn liquid and column chromatography technique is conjunction with UV-spectrophotometry and spectrofluorescent analysis were used to study lipid peroxidation products accumulated in human lenses during cataract formation by means of chromatographic separation in regard to the molecular weight and polarity properties. Cataract is characterized by the appearance of certain substances changing UV-absorption lipid spectra in the region of 230 and 274 nm and having special fluorescence (excitation--320-370 nm), (emission--405-460 nm). The same changes were observed by ultrasoundinduced lipid peroxidation of model lipid samples. The accumulated lipid peroxidation products are concentrated in the same chromatographic fractions that are responsible for the change of UV-absorption and fluorescent spectra of lipids of cataractous lenses. It is the evidence of free radical lipid peroxidation products accumulation in human lenses at cataract formation. Along with the formation of diene and triene conjugates in the lens lipids, cataract is characterized by the formation of cetodienes and of low molecular weight lipid fluorescent products of fatty acids oxidation with low polarity due to the appearance of tetraene derivatives of polyunsaturated fatty acids. The particular features of mature cataract are an increased intensity of long-wave lipid fluorescence in the blue-green region (430-460 nm) of the spectrum, formation of high molecular weight fluorescent lipid peroxidation products with high polarity, and smooth decrease in absorbance in the region of 220-330 nm. During cataract formation products of deep lipid peroxidation resulting from radical phospholipids and fatty acids polymerisation are accumulated. It is supposed that lipid peroxidation is an initial phase of membrane desintegration and formation of HMW-proteins in cataract.