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PubMed1969

Sphingolipids in bean leaves (Phaseolus vulgaris).

Phytoglycolipid has been isolated for the first time from plant leaves (Phaseolus vulgaris). The purified product (almost identical with the phytoglycolipid isolated from flax seed) was a ceramide attached through phosphate diester linkage to an oligosaccharide, which consisted of the usual trisaccharide unit (inositol, hexuronic acid, hexosamine) to which were attached mannose, galactose, and arabinose. The major fatty acids were the saturated 2-hydroxy C(22), C(24), and C(26) acids; the major long-chain bases were dehydrophytosphingosine (d-ribo-1,3,4-trihydroxy-2-amino-8-trans-octadecene) (53%) and phytosphingosine (d-ribo-1,3,4-trihydroxy-2-amino-octadecane) (32%). A ceramide and a cerebroside were also isolated. In the ceramide the major fatty acids and the major long-chain bases were the same as in the phytoglycolipid. In the cerebroside, the fatty acid composition was similar to that in the ceramide and phytoglycolipid, but the long-chain bases consisted of dehydrophytosphingosine and phytosphingosine (7:1) with a substantial amount of unidentified long-chain base. The sugar component was glucose.

Amino Alcohols↗
PubMed1983

Changes in nervous system glycolipids during metamorphosis of Xenopus laevis.

Qualitative and quantitative changes occurring in the myelin marker glycolipids, cerebrosides, sulfatides, and monogalactosyl diglyceride, in the nervous system (brain, spinal cord, and tail) of Xenopus laevis during its metamorphic stages were analyzed by normal and reverse-phase high performance liquid chromatography. The concentration of these glycolipids increased rapidly in brain until the tadpole reached the middle of metamorphosis, fluctuated slightly, decreased until metamorphosis was completed, and increased once more as the frog matured. Similar changes were observed in the spinal cord, but the decrease of glycolipids occurred at a later stage of metamorphosis. The glycolipid level in tail nerve reached a peak at the beginning of metamorphosis and then rapidly decreased. The ratios of hydroxycerebroside and hydroxysulfatide to respective nonhydroxylipids in brain, spinal cord, and tail remained constant throughout the metamorphic change but differed in each tissue. The tail contained the highest ratio. The glycolipids in sciatic nerve generated during the metamorphosis had an even higher hydroxyl lipid/nonhydroxy lipid ratio. The cerebrosides contained extremely high concentrations of monounsaturated fatty acids with very long carbon chains (C22-C25) and this homolog composition remained almost unchanged throughout metamorphosis. These results indicate that active degradation of these glycolipids, and probably of myelin, occurs but the glycolipid composition of myelin appears to remain the same throughout the metamorphic process. The significance of these findings is discussed from a morphological standpoint.

Animals↗
PubMed1980

[Development of brain lipids in rats receiving a fat-free diet with respect to myelinization].

Wistar rats were fed during the whole time of gestation with a fat-free diet. The diet regime was continued for the pups and mothers after term up to day 56 post partum. Phospholipids, cholesterol, and cerebrosides were estimated in the fetal brain at the 22nd day of gestation and in the brains of the new born animals at the 14th and 56th day post partum. The molar ratios typical for mature of myeline were followed up. Fat-free diet caused a reduction of brain weight by 50 per cent in fetuses at day 22 of gestation if compared with control animals. At day 14 and 56 post partum, however, this differences has been adjusted. Within the main phase of myelinization (14th-56th day) the brains of the diet animals showed an increased accumulation of phospholipids, a lower rise in cholesterol, and a strongly depressed accumulation of cerebrosides if compared with the control group. The results support the view that the fat-free diet may lead to a persistence of early states in mature of the myeline with an enrichment in membrane structures corresponding to early myeline.

Aging↗
PubMed1977

In vivo metabolism of ceramides in rat brain. Fatty acid replacement and esterification of ceramide.

Three double-labeled ceramides, [1-14C]lignoceroyl D-erythro-[1-3H]sphingosine, [1-14C]palmitoyl D-erythro-[1-3H]sphingosine and D-[1-14C]cerebronoyl D-erythro-[3-3H]-sphingosine, were prepared and injected separately into the brains of 18-day-old rats. The animals were killed after 2 h and various sphingolipids were isolated and purified. These lipids were further fractionated into subgroups depending on their fatty acid content (nonhydroxy or alpha-hydroxy, shorter chain or longer chain), 3H/14C ratios obtained in ceramides, cerebrosides, and sphingomyelins containing different fatty acids from the injected material were much higher than the initial ratio. This observation indicates that a replacement of the fatty acid occurred in the injected ceramide. Comparison of the 3H/14C ratios of the cerebrosides and sphingomyelin in a specific fatty acid group with the ratios of the corresponding ceramide indicated that most of these lipids were derived directly from the ceramide. The 3H/14C ratio of the hydroxycerebroside obtained from cerebronyl sphingosine-injected brain was nearly twice the ratio of the injected material. In addition to these lipids, considerable radioactivity was incorporated into an unknown nonpolar material in the brains which had been injected with [1-14C]lignoceroyl or [1-14C]palmitoyl [1-3H]sphingosine. This material was tentatively identified as ceramide fatty acid ester. The 3H/14C ratio of the ester was identical to that of the injected material.

Animals↗
PubMed1981

Lipid analysis in nerve biopsy specimens of hypertrophic neuropathy.

We performed a lipid analysis on nerve biopsy specimens in two cases of degenerative hypertrophic neuropathy. Quantitative analysis of the major lipid classes, ie, cholesterol, cerebrosides, sulfatides, ethanolamine phospholipids, phosphatidyl-choline, phosphatidyl-serine, phosphatidyl-inositol, sphingomyelin, and gangliosides, were performed. The two cases exhibited extreme decreases in levels of lipids that could be related to the very low myelin content of these nerves. Cholesterol and phospholipid levels were especially reduced. Cerebrosides and sulfatides were not modified in the same proportion, as could have been predicted from the degree of demyelination. This relative glycolipid increase could be due to the very high Schwann cell proliferation.

Adolescent↗
PubMed1979

Endoneurial lipid composition of normal human sural nerve.

The endoneurial lipid composition was determined in 7 human sural nerves from subjects without known neurological disease. The nerves were morphologically normal, with myelinated fiber density of 7,710 +/- 1,210/mm2 (mean +/- SD). Endoneurium contained 30.7 +/- 1.5 mg total lipid per 100 mg of dry weight. Cholesterol was the predominant lipid (9.1 +/- 1.0 mg). Cholesterol ester was present only in very small quantities (0.2 +/- 0.1 mg). Cerebroside concentration was 4.5 +/- 0.3 mg, and sulfatide was 1.5 +/- 0.3 mg. The most abundant phospholipid was sphingomyelin (4.3 +/- 0.3 mg), followed by phosphatidylethanolamine (4.1 +/- 0.2 mg), phosphatidylcholine (3.8 +/- 0.2 mg), and phosphatidylinositol-phosphatidylserine (1.7 +/- 0.2 mg). Eighty-one percent of cerebroside nonhydroxy fatty acids were long chain (C20 to C26), and 67% were saturated. Technological advances now permit microchemical lipid analysis of human sural nerve biopsies in cases of neuropathy. When compared with our normative data, such studies may further the understanding of peripheral nerve disorders.

Adolescent↗
PubMed1993

Effects of 60 Hz electric and magnetic fields on the development of the rat cerebellum.

The effects of extremely low frequency (ELF) electromagnetic (EM) fields on the maturation of the rat cerebellum were studied. Newborn rats were exposed to 60 Hz electric and magnetic fields under three different combinations in a specially constructed apparatus. The pups were irradiated for 7-8 h daily, with a 30-min interruption for nursing. Pups were kept with their mothers for the remainder of the time. After approximately 1, 2, or 3 weeks of exposure, the pups were killed. Control pups were sham exposed. The somatic growth of the irradiated rats did not show any significant difference from sham-exposed controls. At 1 kV/m and 10 gauss exposure, there was a small but statistically significant decrease in cerebellar mass. In rats exposed at 1 kV/m and 10 gauss, DNA and RNA levels were significantly higher than those in sham-exposed controls at 6 and 13 days of age, but at 20 days, these two biochemical constituents were similar in both groups of rats. The ELF-EM treatment had no effect on protein and cerebroside concentrations. In terms of age effects, DNA and RNA exhibited increases from 6 to 13 days of age, and declined from 13 to 20 days. Protein and cerebroside levels exhibited increases during the 6-20-day periods. In rats exposed at 100 kV/m and 1 gauss, the DNA levels were initially less than those of sham-exposed controls at 8 days of age, reached approximately the same levels at 14 days, and then were higher than those of controls at 22 days. There was, therefore, a significant ELF-EM effect as well as a significant interaction between age and ELF-EM exposure. In terms of age effects, DNA levels for both control and exposed animals increased from 8 to 14 days. From 14 to 22 days, DNA levels of exposed rats continued to increase while those of the controls decreased. This age effect was significant. RNA levels in both groups of animals showed increases from 8 to 14 days of age, but the increase was less for the irradiated animals than for the controls. From days 14 to 22, RNA levels for both groups showed a reduction, but the decrease was greater in the irradiated than in control rats. ELF-EM treatment significantly reduced protein levels at 8 days of age, but at 14 to 22 days, protein levels of exposed rats were higher than those of controls.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1993

Effects of 60 Hz electric and magnetic fields on maturation of the rat neopallium.

This study was undertaken to determine the effects of extremely low frequency (ELF; 60 Hz) electromagnetic (EM) fields on somatic growth and cortical development, as well as biochemical and morphological maturation, of the rat neopallium. On the fifth day of pregnancy, female rats were put in pairs into plastic cages that were housed in a specially constructed apparatus for irradiation under three separate sets of combination and intensity: 1) 1 kV/m and 10 gauss; 2) 100 kV/m and 1 gauss; and 3) 100 kV/m and 10 gauss. The dams were exposed for 23 h daily, from days 5 through 19 postconception, after which they were returned to cages outside the exposure apparatus until they littered. The neonates were culled to eight pups per litter. At 0 (birth), 5, 12, and 19 days postnatally, they were killed for biochemical and morphological studies. Another group of pregnant rats was sham-exposed in an identical apparatus, which was not energized, and the pups were used as controls. The irradiated rats exhibited no physical abnormalities, nor did they show brain deformities such as swelling or herniation following exposure to ELF-EM fields. There was no difference in somatic growth between control and exposed rats, but a small reduction in cortical weight was observed in rats exposed at 1 kV/m and 10 gauss, and 100 kV/m and 1 gauss, respectively. Biochemical measurements of DNA, RNA, protein, and cerebroside concentrations indicated that among the three separate exposures, only the neopallium of rats exposed at 1 kV/m and 10 gauss showed a small reduction in DNA level, as well as small reductions in RNA and protein levels. No changes were noticed in cerebroside levels in any exposed animals, and there were no differences in protein/DNA and cerebroside/DNA ratios between control and exposed rats. Morphological observations did not reveal any detectable alterations in the irradiated rats. These results indicate that exposure to ELF-EM fields caused minimal or no changes in somatic growth and cerebral development of the rat.

Animals↗
PubMed1982

Analysis of molecular species of phospholipids by field desorption mass spectrometry.

Various glycerophospholipids including their trimethylsilyl and t-butyldimethylsilyl derivatives and cerebroside were analysed by field desorption mass spectrometry with a silicon emitter. Choline glycerophospholipids with diacyl residues and also alk-1'-enyl and acyl residues gave the readily interpretable field desorption mass spectra in which a sodium cluster ion [M+NA]+ was a base peak. As to phosphatidylethanolamine and cerebroside, a protonated molecular ion [M+H+]+ was a base peak. The TMS and TBDMS derivatives gave a molecular ion [M]+. The field desorption analysis of natural phospholipids from myelin was carried out in comparison with the gas chromatographic mass spectrometric analysis.

Animals↗
PubMed1984

Biosynthesis of phospholipids and sphingolipids from acetoacetate and glucose in different regions of developing brain in vivo.

The incorporation of 14C-label from subcutaneously injected [3-14C]acetoacetate and [U-14C]glucose into phospholipids and sphingolipids in different regions of developing rat brain was determined. In all regions, phosphatidylcholine was the lipid synthesized most readily from either substrate. The percentages of radioactivity in other phospholipids and most sphingolipids remained relatively constant throughout postnatal development. An exceptional increase in the percentage of radioactivity incorporated into cerebroside, coinciding with a decrease of incorporation into phosphatidylcholine, was first noted on day 12 and continued until a maximal level was reached between days 18 and 20 of postnatal age. These developmental changes in preferential synthesis of lipids were associated with increased demands for phospholipids and cerebroside during the early and late postnatal stages, respectively. There was no difference in accumulation of radioactivity from acetoacetate, expressed as dpm of [14C]acetoacetate recovered in phospholipids plus sphingolipids per g of tissue, among all brain regions during the first 5 days of life. During active myelination (12 to 20 days of age); however, the amount of 14C-label was highest in brain stem, ranging from 1.9- to 2.3-fold greater than values for cerebrum and thalamus. The region with the next highest accumulation was cerebellum, followed by midbrain. During the same period, brain stem was likewise the most active site of accumulation of radioactivity from 14C-labeled glucose. Higher amounts of [14C]acetoacetate label accumulated in lipids of brain stem and cerebellum, relative to midbrain, thalamus, and cerebrum, coincide with evidence that active myelination begins in the hindbrain and proceeds rostrally toward the forebrain. Ketone bodies could therefore serve as a potential source of phospholipids and sphingolipids for brain growth and maturation.

Acetoacetates↗
PubMed1989

Inhibition of the synthesis of glycosphingolipids affects the translocation of proteolipid protein to the myelin membrane.

Brain slices obtained from young rats were incubated with different radioactive precursors, in the presence and absence of L-cycloserine (an inhibitor of the synthesis of sphingosine) in order to explore the possibility that transport of proteolipids--and specifically of the major myelin proteolipid PLP--to the myelin membrane could be coupled to the transport of cerebrosides or sulfatides. At a concentration of 0.15 mM L-cycloserine, the incorporation of [3H] glycine into total proteins, proteolipid apoproteins (APL), PLP, and myelin basic proteins (MBP) of the total homogenate was unaffected by the presence of the inhibitor, whereas the incorporation of [3H] serine into glycosphingolipids decreased markedly. Under similar incubation conditions, the entry of labeled APL and of PLP into the myelin membranes in the presence of L-cycloserine decreased markedly (50%) in comparison to controls. Entry of MBP was not affected by the inhibitor. These results indicate that when synthesis of glycosphingolipids is inhibited by L-cycloserine, thus decreasing the availability of cerebrosides and sulfatides, the translocation of PLP to myelin is disrupted, suggesting that its transport through the oligodendroglial cell could be coupled to the transport of glycosphingolipids and, most probably, of sulfatides.

Animals↗
PubMed1993

Protein kinase C activity modulates myelin gene expression in enriched oligodendrocytes.

Protein kinase C (PKC) and its potential role in myelin gene expression were investigated in primary cultured rat oligodendrocytes. The major myelin genes were expressed in a developmentally coordinated manner in cultured oligodendrocytes. PKC activity in these cells was similarly regulated with differential expression of PKC isozyme mRNAs. PKC-gamma mRNA was expressed transiently and was most abundant in 9-day cells in vitro. PKC-alpha and PKC-beta mRNAs were present at low levels throughout development in these cells, and their expression increased in 18-25 day cells. Immunocytochemical colocalization of PKC with oligodendrocyte-specific markers--O4, galactosyl cerebroside, MBP, and PLP--in enriched oligodendrocyte cultures suggested that the PKC enzyme activities assayed in these cultures were predominantly contributed by oligodendrocytes. PKC inhibition resulting from long-term exposure to 4 beta-phorbol-12,13-dibutyrate (4 beta-PDB) reduced steady-state levels of MBP, PLP, MAG, CNP, and PKC-alpha mRNAs, as detected by slot blots or in situ hybridization, and downregulated the oligodendrocyte-specific markers O4, galactosyl cerebroside, and the major constituent proteins MBP and PLP, as detected by immunocytochemistry. PKC-mediated downmodulation of myelin gene expression was most profound in normally differentiating oligodendrocytes at or before the onset of myelin protein synthesis. Six-day oligodendrocytes were most susceptible to such modulation. To elucidate the mechanism of reduction in various myelin gene messages upon modulation of PKC, we analyzed mRNA levels in oligodendrocytes, which were pretreated with either the transcriptional inhibitor actinomycin D or the protein synthesis blocker cycloheximide before exposure to 4 beta-PDB. Our results demonstrate that the PKC inhibition-mediated loss in myelin mRNA levels did not require the transcription of any genes, but appeared to be at least partially dependent on continuous protein synthesis.

Animals↗
PubMed2001

Comparative analysis of glycosylinositol phosphorylceramides from fungi by electrospray tandem mass spectrometry with low-energy collision-induced dissociation of Li(+) adduct ions.

Glycosylinositol phosphorylceramides (GIPCs) are a class of acidic glycosphingolipids (GSLs) expressed by fungi, plants, and certain parasitic organisms, but not found in cells or tissues of mammals or other higher animals. Recent characterizations of fungal GIPCs point to an emerging diversity which could rival that already known for mammalian GSLs, and which can be expected to present a multitude of challenges for the analytical chemist. Previously, the use of Li(+) cationization, in conjunction with electrospray ionization mass spectrometry (ESI-MS) and low-energy collision-induced dissociation tandem mass spectrometry (ESI-MS/CID-MS), was found to be particularly effective for detailed structural analysis of monohexosylceramides (cerebrosides) from a variety of sources, including fungi, especially minor components present in mixtures at extremely low abundance. In applying Li(+) cationization to characterization of GIPCs, a substantial increase in both sensitivity and fragmentation was observed on collision-induced dissociation of [M + Li](+) versus [M + Na](+) for the same components analyzed under similar conditions, similar to results obtained previously with cerebrosides. Molecular adduct fragmentation patterns were found to be systematic and characteristic for both the glycosylinositol and ceramide moieties with or without phosphate. Interestingly, significant differences were observed in fragmentation patterns when comparing GIPCs having Manalpha1 --> 2 versus Manalpha1 --> 6Ins core linkages. In addition, it was useful to perform tandem product ion scans on primary fragments generated in the orifice region, equivalent to ESI-(CID-MS)(2) mode. Finally, precursor ion scanning from appropriate glycosylinositol phosphate product ions yielded clean molecular ion profiles in the presence of obscuring impurity peaks. The methods were applied to detailed characterization of GIPC fractions of increasing structural complexity from a variety of fungi, including a non-pathogenic Basidiomycete (mushroom), Agaricus blazei, and pathogenic Euascomycete species such as Aspergillus fumigatus, Histoplasma capsulatum, and Sporothrix schenckii. The analysis confirmed a remarkable diversity of GIPC structures synthesized by the dimorphic S. schenckii, as well as differential expression of both glycosylinositol and ceramide structures in the mycelium and yeast forms of this mycopathogen. Mass spectrometry also established that the ceramides of some A. fumigatus GIPC fractions contain very little 2-hydroxylation of the long-chain fatty-N-acyl moiety, a feature that is not generally observed with fungal GIPCs.

Agaricus↗
PubMed1997

Sphingolipids--the enigmatic lipid class: biochemistry, physiology, and pathophysiology.

The "sphingosin" backbone of sphingolipids was so named by J. L. W. Thudichum in 1884 for its enigmatic ("Sphinx-like") properties. Although still an elusive class of lipids, research on the involvement of sphingolipids in the signal transduction pathways that mediate cell growth, differentiation, multiple cell functions, and cell death has been rapidly expanding our understanding of these compounds. In addition to the newly discovered role of ceramide as an intracellular second messenger for tumor necrosis factor-alpha, IL-1beta, and other cytokines, sphingosine, sphingosine-1-phosphate, and other sphingolipid metabolites have recently been demonstrated to modulate cellular calcium homeostasis and cell proliferation. Perturbation of sphingolipid metabolism using synthetic and naturally occurring inhibitors of key enzymes of the biosynthetic pathways is aiding the characterization of these processes; for examples, inhibition of cerebroside synthase has indicated a role for ceramide in cellular stress responses including heat shock, and inhibition of ceramide synthase (by fumonisins) has revealed the role of disruption of sphingolipid metabolism in several animal diseases. Fumonisins are currently the focus of a FDA long-term tumor study. This review summarizes recent research on (i) the role of sphingolipids as important components of the diet, (ii) the role of sphingoid base metabolites and the ceramide cycle in expression of genes regulating cell growth, differentiation, and apoptosis, (iii) the use of cerebroside synthase inhibitors as tools for understanding the role of sphingolipids as mediators of cell cycle progression, renal disease, and stress responses, and (iv) the involvement of disrupted sphingolipid metabolism in animal disease and cellular deregulation associated with exposure to inhibitors of ceramide synthase and serine palmitoyltransferase, key enzymes in de novo sphingolipid biosynthesis. These findings illustrate how an understanding of the function of sphingolipids can help solve questions in toxicology and this is undoubtedly only the beginning of this story.

Amidohydrolases↗
PubMed1998

Induction of interferon-alpha by glycoprotein D of herpes simplex virus: a possible role of chemokine receptors.

The induction of type I interferons by most RNA viruses is initiated by virus-derived double-stranded (ds)RNA. However, retro- and DNA-viruses, which do not synthesize dsRNA, must rely on different mechanisms of induction. For human immunodeficiency virus type 1 (HIV-1), recombinant glycoproteins 120 or 160 suffice to induce interferon (IFN)-alpha in blood-derived lymphocytes [H. Ankel, M. R. Capobianchi, C. Castilletti, and F. Dianzani (1994). Virology 205, 34-43]. Here we show that for herpes simplex virus type 1 (HSV-1) recombinant glycoprotein, gD is the major inducer, whereas gB, gC, gE, gG, gI, and the complex of gH and gL are poor inducers. The recombinant extramembrane fragment of gD was sufficient to induce IFN-alpha levels comparable to that of intact virus. Like with HIV-1, induction was inhibited by a monoclonal antibody that recognizes cerebrosides and sulfatides. Furthermore, monoclonal antibodies specific for the chemokine receptors CCR3 and CXCR4 also blocked induction. We conclude that HSV-1 induces IFN-alpha by interaction of its glycoprotein gD with appropriate receptors on IFN-producing cells. Based on the known receptor roles of galactosyl cerebrosides and chemokine receptors in HIV infection, such structures on IFN-producing cells could also participate in the induction of IFN-alpha by HSV-1.

Animals↗
PubMed1983

Myelination of regenerating sciatic nerve of the rat: lipid components and synthesis of myelin lipids.

Changes of lipid, free fatty acid, protein, DNA, and RNA content in proximal and distal segments of regenerating sciatic nerve, from 14 to 120 days after crush, were determined. During the early stage of Wallerian degeneration, a marked decrease of phospholipid, cerebroside and sulfatide content and, in contrast, a marked increase of protein, DNA, RNA, and free fatty acid content, in the distal segment of crushed nerve compared to control, was observed. A gradual increase of phospholipid, cerebroside, and sulfatide levels, approaching normal values, and a gradual slope in the increase of protein, DNA, RNA, and free fatty acid levels over the ensuing time periods of regeneration was seen. Total cholesterol content was relatively constant during regeneration, slightly increasing at day 120. The activity of 2', 3'-cyclic nucleotide 3'-phosphodiesterase (CNPase) of myelin fraction purified from distal segment of regenerating sciatic nerve showed a significant increase in the 30-120 day regenerating period. A marked increase of the incorporation of [2-3H]glycerol and of [Me-14C]choline into myelin lipids of distal segment of regenerating nerve, was found. Labeling of myelin lipids with [3H]oleic acid (injected intravenously seven days before crush) support the evidence that a similar pattern of degeneration exists between two different types of trauma, i.e. nerve crush or cut. The findings suggest that, in the distal segment of crushed nerve, the lipid content as well as the myelin lipid synthesis increase as the regeneration period proceeds.

2',3'-Cyclic-Nucleotide Phosphodiesterases↗
PubMed1985

Levels of sulfatide synthesis distinguish oligodendroglia in different stages of maturation.

In the central nervous system, oligodendroglia elaborate extensive quantities of membranes to form the multilamellar myelin sheath. Whether the production of extensive networks of processes by oligodendroglia in culture is a similar type of phenomenon as the formation of myelin is an unanswered question. Rat oligodendroglia, prepared by a modification of a differential shaking and plating method, elaborate extensive processes in culture. In contrast, bovine oligodendroglia, obtained by a bulk-isolation method, produce whorls of membrane lamellae, adjacent to the cell soma. The incorporation of various radiolabeled substrates into specific lipids was compared with the two cell types. It was found that rat oligodendroglia do produce myelin specific lipids, but at a lower level than bovine oligodendroglia which are actively synthesizing myelin lipids, especially cerebrosides, from a variety of substrates. Interestingly sulfatides are produced at a higher level in the cells not producing myelin, rat oligodendroglia. Other lipids that are associated with myelination (cerebrosides with alpha-hydroxy fatty acids and phosphatidylinositides) are produced at higher levels in bovine oligodendroglia. Thus it appears that the extension of processes by oligodendroglia in culture is a different phenomenon than the production of myelin membranes and requires lower levels of myelin lipids.

Animals↗
PubMed1986

Myelin lipids: a phylogenetic study.

The lipid composition of CNS and PNS myelin was studied in rat, Xenopus, trout and Torpedo. The main difference lay in the proportion of cerebrosides, which decreased in the sequence rat greater than Xenopus greater than Torpedo greater than trout. In addition Torpedo CNS and PNS myelins were extremely rich in sulfatides. In some respects, Torpedo appeared closer to tetrapods than trout. Otherwise the proportion of the different lipid classes did not reveal any clear evolutionary trends. The presence of hydroxylated galactolipids in CNS myelin was investigated in several additional species. Considerable amounts were found in Torpedo, Polypterus, Protopterus, lizard, and chicken, with the highest values in rat and anurans. Only very small amounts of hydroxylated cerebrosides were detected in trout and in axolotl, while newt had none. This parameter appears therefore of doubtful usefulness for phylogenetic studies. In contrast to myelin proteins, myelin lipids are of limited value for establishing phylogenetic relationships among vertebrates.

Amphibians↗