[On the production of cerebroside antibodies following intradermal injection of cerebroside-protein adjuvant emulsions].
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A cerebroside sulphatase (cerebroside-3-sulphate 3 sulphohydrolase, EC 3.1.6.8) assay based on radio thin-layer chromatography is described. The substrate was labelled by the catalytic addition of tritium to cerebroside sulphate. Using this assay the cerebroside sulphatase activity of sulphatase A (Aryl-sulphate sulphohydrolase, EC 3.1.6.1) from human liver and kidney in the absence of activators was investigated. The pH optimum of this reaction depends on the buffer concentration, being pH 4.5 at 50 mM and 5.3 at 10 mM sodium formate. With the latter concentration the apparent Km for cerebroside sulphate is 0.06 mM; SO2-4 and nitrocatechol sulphate inhibit noncompetitively with a Ki of 4.51 mM for Na2SO4 and 0.43 mM for nitrocatechol sulphate. The cerebroside sulphatase activity of sulphatase A is highly dependent on the ionic strength. The optimum sodium formate concentration is 10 mM, and the cerebroside suophatase activity decreases rapidly with increasing buffer concentration. The same concentration dependence is observed in the inhibitory effect of cerebroside sulphate on the arylsulphatase reaction. The inhibition decreases at increasing buffer concentrations, becoming an activation at 70 mM sodium formate. The progress curve of the cerebroside sulphatase reaction shows a deviation from linearity similar to that of the arylsulphatase reaction. Investigation of the effect of preincubation with cerebroside sulphate on the arylsulphatase activity of the enzyme shows that cerebroside sluphatase activity and inactivation of the enzyme by cerebroside sulphate occur simultaneously. These observations are interpreted as supporting the assumption that cerebroside suophate and arylsulphates are degraded at an identical active site on the same enzyme. Differences in the properties of the cerebroside sulphatase and the arylsulphatase reaction of the enzyme may be attributed to the differences in the physiocochemical state of the two substrates.
The synthesis and turnover of cerebrosides and phospholipids was followed in microsomal and myelin fractions of developing and adult rat brains after an intracerebral injection of [U-14C]serine. The kinetics of incorporation of radioactivity into microsomal and myelin cerebrosides indicate the possibility of a precursor-product relationship between cerebrosides of these membranes. The specific radioactivity of myelin cerebrosides was corrected for the deposition of newly formed cerebrosides in myelin. Multiphasic curves were obtained for the decline in specific radioactivity of myelin and microsomal cerebrosides, suggesting different cerebroside pools in these membranes. The half-life of the fast turning-over pool of cerebrosides of myelin was 7 and 22 days for the developing and adult rat brain respectively. The half-life of the slowly turning-over pool of myelin cerebrosides was about 145 days for both groups of animals. The half-life of the rapidly turning-over microsomal cerebrosides was calculated to be 20 and 40 h for the developing and adult animals respectively. The half-life of the intermediate and slowly turning-over microsomal cerebrosides was 11 and 60 days respectively, for both groups of animals. The amount of incorporation of radioactivity into microsomal cerebrosides from L-serine was greatly decreased in the adult animals, and greater amounts of the precursor were directed towards the synthesis of phosphatidylserine. In the developing animals, considerable amounts of cerebrosides were synthesized from L-serine, besides phosphatidylserine. The time-course of incorporation indicated that a precursor-product relationship exists between microsomal and myelin phosphatidylserine. The half-life of microsomal phosphatidylserine was calculated to be about 8 h for the fast turning-over pool in both groups of animals.
Cerebrosides have been isolated from adult human aortic tissue. Each aorta was divided into portions classified as normal, fatty streaks, fibrous plaques, or complicated lesions. The cerebrosides were isolated by Florisil column chromatography, mild alkaline methanolysis, a second Florisil column, and preparative thin-layer chromatography. The concentration of cerebrosides was higher in fatty streaks than in the more advanced plaques; apparently normal tissue gave the same cerebroside content as plaques found in the same aorta. The quantities of cerebrosides ranged from 0.01 to 0.73% of the total lipid. Of the 16 cerebroside samples isolated, 10 contained glucosyl ceramide, 1 contained galactosyl ceramide, and 5 were not analyzed for specific hexose. The fatty acid distribution was determined for 11 of the samples; it was similar to that of spleen cerebrosides. We suggest that aortic cerebrosides originate in the plasma. "Normal tissue" cerebrosides contained less unsaturated fatty acid than cerebrosides from a diseased area of the same aorta. Preparative thin-layer chromatography, the last step of cerebroside isolation, always separated at least two unidentified substances. One of these substances yielded both glucose and galactose on acid hydrolysis. Their removal from the cerebrosides accounts for the lower values for cerebroside compared to other authors' determinations.
From the pulp of Euphoria longana (Longan Arillus), three cerebroside molecular species have been isolated. Six known cerebrosides, soyacerebrosides I and II, 1-O-beta-D-glucopyranosyl-(2S,3R,4E,8E)-2-(2'-lignoceroylamino)-4,8-octadecadiene-1,3-diol (longan cerebroside I) and its 8Z isomer (longan cerebroside II), momor-cerebroside I, and phytolacca cerebroside, were identified as major components of these cerebroside molecular species. All the cerebrosides were shown to be a mixture of geometrical isomers (8E and 8Z) of sphingosine-type or phytosphingosine-type glucocerebrosides possessing 2-hydroxy fatty acids. The structures of these cerebrosides have been determined on the basis of chemical and spectroscopic evidence.
We studied markers of myelin content and of the rate of myelination in brains of mice between 8 and 20 weeks of age. During the 12-week time-course, control animals showed slight increases in the content of oligodendroglial-specific cerebroside, as well as cholesterol (enriched in, but not specific to, myelin). In contrast, synthesis of these lipids, as assayed by in vivo incorporation of (3)H(2)O, was substantial, indicating turnover of 0.4% and 0.7% of total brain cerebroside and cholesterol, respectively, each day. We also studied mice exposed to a diet containing 0.2% of the copper chelator, cuprizone. After 6 weeks 20%, and by 12 weeks, over 30% of brain cerebroside was gone. Demyelination was accompanied by down-regulation of mRNA expression for enzymes controlling myelin lipid synthesis (ceramide galactosyl transferase for cerebroside; hydroxymethylglutaryl-CoA reductase for cholesterol), and for myelin basic protein. Synthesis of myelin lipids was also greatly depressed. The 20% cerebroside deficit consequent to 6 weeks of cuprizone exposure was restored 6 weeks after return to a control diet. During remyelination, expression of myelin-related mRNA species, as well as cerebroside and cholesterol synthesis were restored to normal. However, in contrast to the steady state metabolic turnover in the control situation, all the cerebroside and cholesterol made were accumulated. To the extent that accumulating cerebroside is targeted for eventual inclusion in myelin (discussed) the rate of its synthesis is proportional to remyelination. With our assay, in vivo rates of cerebroside synthesis can be determined for a time window of the order of hours. This offers greater temporal resolution and accuracy relative to classical methods assaying accumulation of myelin components at time intervals of several days. We propose this experimental design, and the reproducible cuprizone model, as appropriate for studies of how to promote remyelination.
Cerebrosides obtained from the guinea pig Harderian gland were analyzed. The purified cerebrosides gave a single spot on thin-layer chromatography, the Rf value being similar to that of phrenosine obtained from whale brain. The cerebrosides consisted of 74.7% of glucosylceramide and 25.3% of galactosylceramide. The fatty acid composition of these cerebrosides was 0.7% of non-hydroxy fatty acids and 99.3% of alpha-hydroxy fatty acids. Among these alpha-hydroxy fatty acids, a small amount of methyl branched acids was detected. The substituted position of methyl branching of alpha-hydroxy fatty acids was the 16th carbon atom from the carboxyl end irrespective of the carbon chain length. The long chain bases were composed of sphinganine (78%) and sphingenine (22%). 4-D-Hydroxysphinganine was not found. The most remarkable feature of the long chain bases of cerebrosides in the Harderian gland was the presence of a large amount of methyl branched sphinganine. The cerebrosides obtained from the cerebrum and cerebellum of the same animal were also analyzed. The sugar, fatty acid, and long chain base compositions of these cerebrosides were similar to those of whale brain cerebrosides. Methyl branched sphinganine was not found in guinea pig brain.
Cerebrosides A and C, compounds categorized as glycosphingolipids, were isolated in our previous study from the rice blast fungus (Magnaporthe grisea) as novel elicitors which induce the synthesis of rice phytoalexins. In this paper, these cerebroside elicitors showed phytoalexin-inducing activity when applied to plants by spray treatment and also induced the expression of pathogenesis-related (PR) proteins in rice leaves. This elicitor activity of the cerebrosides showed the structural specificity as that for the induction of phytoalexins. Ceramides prepared from the cerebrosides by removal of glucose also showed the elicitor activity even in lower level compared to the cerebrosides. In field experiments, the cerebroside elicitors effectively protected rice plants against the rice blast fungus, an economically devastating agent of disease of rice in Japan. The cerebrosides elicitors protected rice plants from other disease as well and were found to occur in a wide range of different phytopathogens, indicating that cerebrosides function as general elicitors in a wide variety of rice-pathogen interactions.
Cerebrosides are concentrated in the myelin sheath where they account for about 20% of the total lipid of the membrane. The present paper is concerned with the role and localisation of these glycolipids in the myelin lamellae. Isolated central nerve myelin preparations have been treated with two probes to investigate cerebroside accessibility in the membrane. The action of galactose oxidase on the galactose headgroups of cerebrosides is followed and quantitated by recovery of the modified glycolipid and resolution of either the 6-aldehydo sugar or galactose remaining by gas-liquid chromatography. With isolated myelin preparations only some 40--50% of the cerebroside galactose is attacked by galactose oxidase at 20 degrees C. With periodate at 20 degrees C over 90% of the galactose headgroups are oxidised in 3 h while the figure is 50--55% over the same time period at 4 degrees C rising to 85% after 22 h. With multilamellar liposomes of mixed myelin lipids only some 20--25% of the available cerebroside is oxidised at 4 degrees C, the reaction being complete in 2 h. The results are discussed in relation to the dispositon of cerebroside in the myelin lamellae. A major location on the external face of the membrane system (intraperiod dense line) is favoured. A role for cerebroside in myelin in terms of increasing the stability and resistance of the lipid phase to ion movement is suggested.
Candida lipolytica yeast was grown batchwise on glucose medium. Cerebrosides were isolated from the sphingolipid fraction of total lipids using column chromatography and separated into two compounds by high-performance thin-layer chromatography. Glucose was detected as the sole sugar constituent in cerebrosides. The fatty acid composition of cerebrosides was characterised by a predominance of saturated fatty acids and by a high proportion of fatty acids with 16 carbon atoms. The dominant fatty acid was h16:0. The principal long-chain base components of both cerebroside species were trihydroxy bases, 18- and 20-phytosphinosine. The unique characteristic of cerebrosides was the presence of a high proportion of sphingosine (one-fourth of the total long-chain bases), which is a common characteristic of mammalian sphingolipids and rarely occurs in yeast cerebrosides. The ceramide moiety profile of cerebrosides is similar to that of epidermal ceramides, which implies a possibility for their application in care cosmetics.
Calorimetric and Fourier transform infrared (FTIR) spectroscopic studies have been made of the polymorphism exhibited by bovine brain cerebroside-water systems, and the effect of cholesterol and dipalmitoylphosphatidylcholine (DPPC) upon this polymorphism was investigated. The conversion of the cerebroside from the thermodynamically stable to the metastable form is found to be accompanied by spectral changes, indicating a decrease in cerebroside headgroup hydration and a rearrangement of the hydrogen-bond network. The incorporation of low concentrations of cholesterol and DPPC into cerebroside bilayers broadens the thermal transitions associated with the cerebroside as a result of the disruption of cerebroside-cerebroside interactions. This disruption is evident in the spectra of cerebroside/cholesterol mixtures.
1. Sulphatase A (cerebroside sulphatase) (EC 3.1.6.1.) and a 12-fold excess of its physiological activator protein were chromatographed together on Sephadex G-75. The elution buffer was the same as that used in the enzymic degradation of sulphatides. The two proteins were eluted in different peaks indicating that no stable complex formed. 2. Activator protein was incubated with sulphatides under conditions used favouring the sulphatase activity. Incubation solutions were then examined by electrophoresis on a polyacrylamide gel gradient. An one-to-one complex between activator and sulphatides was observed. Half maximal binding occurred with 2.5 nmol of sulphatides together with 1 or 2 nmol of activator in 100 micronl. 3. Cerebrosides as the enzymic degradation products of sulphatides, bind also to the activator protein. A ratio of one-to-one could possibly be obtained at high cerebroside concentrations. The binding to cerebrosides is less specific than that to sulphatides. A 7-fold excess of cerebrosides was necessary for half maximal binding. 4. In a mixture of sulphatides and cerebrosides the formation of the complex with the activator protein is partly inhibited. The total amount of bound lipids changed as the composition of the lipid mixture was varied. In a one-to-one mixture of the two lipids 60% of the total bound lipids are sulphatides and 40% are cerebrosides.
Previous studies on myelinating rat brain indicated that microsomes, Golgi-enriched and cytosol fractions may process galactolipids destined for myelin. To extend these findings we labeled brain galactolipids in vivo and determined the specific radioactivity of cerebrosides and sulfatides in several subcellular fractions. 17-day-old rats were treated by intracranial injection with [14C]galactose 60 min prior to and [3H]galactose 15 min prior to killing. Subcellular fractions were prepared from brain stem, and concentrations of cerebrosides and sulfatides were determined, their radioactivity measured and the 3H/14C ratio compared. Our results showed that the heavier Golgi-enriched fraction (designated Fraction 2) is unique in its low galactolipid content and high specific radioactivities of cerebrosides and sulfatides. The low ratio of the specific activity of cerebroside to that of sulfatide in Fraction 2 compared to other fractions indicates that it may be the site of most rapid conversion of newly synthesized cerebrosides to sulfatides. The specific radioactivities of cerebrosides and sulfatides in cytosol are intermediate between those in Golgi-enriched Fraction 2 and microsomes and those in myelin, consistent with the role postulated for cytoplasmic elements in the transport of cerebrosides and sulfatides to myelin.
13C- and 2H-NMR experiments were used to examine the phase behavior and dynamic structures of N-palmitoylgalactosylsphingosine (NPGS) (cerebroside) and cholesterol (CHOL) in binary mixtures. 13C spectra of 13C=O-labeled and 2H spectra of [7,7-2H2] chain-labeled NPGS as well as 3 alpha-2H1 CHOL indicate that cerebroside and CHOL are immiscible in binary mixtures at temperatures less than 40 degrees C. In contrast, at 40 degrees C < t < or = T(C) (NPGS), up to 50 mol% CHOL can be incorporated into melted cerebroside bilayers. In addition, 13C and 2H spectra of melted NPGS/CHOL bilayers show a temperature and cholesterol concentration dependence. An analysis of spectra obtained from the melted 13C=O NPGS bilayer phase suggests that the planar NH-C=O group assumes an orientation tilted 40 degrees-55 degrees down from the bilayer interface. The similarity between the orientation of the amide group relative to the bilayer interface in melted bilayers and in the crystal structure of cerebroside suggests that the overall crystallographic conformation of cerebroside is preserved to a large degree in hydrated bilayers. Variation of temperature from 73 degrees to 86 degrees C and CHOL concentration from 0 to 51 mol% results in small changes in this general orientation of the amide group. 2H spectra of chain-labeled NPGS and labeled CHOL in NPGS/CHOL bilayer demonstrate that molecular exchange between the gel and liquid-gel (LG) phases is slow on the 2H time scale, and this facilitates the simulation of the two component 2H spectra of [7,7-2H2]NPGS/CHOL mixtures. Simulation parameters are used to quantitate the fractions of gel and LG cerebroside. The quadrupole splitting of [7,7-2H2]NPGS/CHOL mixtures and 2H simulations allows the LG phase bilayer fraction to be characterized as an equimolar mixture of cerebroside and CHOL.
Bovine brain cerebrosides have been fractionated into 2-hydroxy fatty acid containing cerebrosides (HFA-CER) and nonhydroxy fatty acid containing cerebrosides (NFA-CER). The thermal behavior of NFA-CER, HFA-CER, and unfractionated cerebroside model membranes has been studied by differential scanning calorimetry. When NFA-CER is cooled at rates greater than or equal to 2.5 degrees C/min, subsequent heating runs exhibit metastable behavior: a low enthalpy exotherm is observed at approximately 50 degrees C (delta H = -(1-3) cal/g), followed by a high enthalpy endotherm at 72 degrees C (delta H = 16-17 cal/g). Systematic variation of cooling/heating protocols indicates that NFA-CER possesses two low-temperature states, one metastable and the other stable. Cooling from the liquid-crystalline state results in formation of the metastable low-temperature polymorph I, which must transform into the stable low-temperature polymorph II before the liquid-crystalline state can be reached again. By analogy with recent X-ray studies of synthetic N-palmitoylgalactosylsphingosine [Ruocco, M. J., Atkinson, D., Small, D. M., Skarjune, R. P., Oldfield, E., & Shipley, G. G. (1981) Biochemistry 20, 5957], it is proposed that metastable polymorph I is dehydrated relative to stable polymorph II. HFA-CER displays no metastability and exhibits a reversible thermal transition at approximately 68 degrees C (delta H = 7.3 cal/g). The thermal behavior of unfractionated cerebrosides is similar to that of HFA-CER, exhibiting a single reversible transition at approximately 67 degrees C (delta H = 6.9 cal/g). These results suggest that a function of hydroxy fatty acids in brain cerebrosides may be to prevent metastable dehydration in the cerebroside-rich myelin membrane.
Cerebrosides, compounds categorized as glycosphingolipids, were found to occur in a wide range of phytopathogens as novel elicitors and to induce the effective disease resistance for rice plants in our previous study. Here, we showed that cerebroside elicitors lead to the accumulation of phytoalexins and pathogenesis-related (PR) protein in cell suspension cultures of rice with the structural specificity similar to that for the rice whole plants. This elicitor activity of the cerebroside was greater than jasmonic acid (JA) and chitin oligomer (which is known to be an elicitor for cell suspension cultures of rice). Treatment of cell suspension cultures with cerebroside and chitin oligomer resulted in a synergetic induction of phytoalexins, suggesting that cerebroside and carbohydrate elicitors, such as glucan and chitin elicitor, enhance the defense signals of rice in vivo. Induction of phytoalexins by the treatment with cerebroside elicitor was markedly inhibited by LaCl(3) and GdCl(3), Ca(2+ )channel blockers. It is possible that Ca(2+) may be involved in the signaling pathway of elicitor activity of cerebroside.
The effect of nicotinic acid on the synthesis of cerebrosides in the brain was studied during brain development. The concentration of cerebrosides in the brain was significantly lower in nicotinic acid-deficient animals than in those receiving a nicotinic acid-supplemented diet. The total lipid concentration in the brain of nicotinic acid-deficient rats was slightly lower than that of rats fed on the nicotinic acid-supplemented diet. Therefore, the ratio of cerebrosides to total lipids of nicotinic acid-deficient rats was markedly lower than that of nicotinic acid-supplemented rats. However, this low cerebroside level in nicotinic acid-deficient rats was restored by the administration of the nicotinic acid-supplemented diet. Synthesis of cerebrosides was followed in the brain of developing rats after intracerebral injection of L-[U]14C]serine. The total amount of radioactivity incorporated into the cerebroside fraction of nicotinic acid-deficient rat was smaller than that of nicotinic acid supplemented rats. These observations suggest that nicotinic acid affects cerebroside synthesis in the brain of rats.