Brain ganglioside patterns of vertebrates

Abstract— The ganglioside content in brains of representatives of six vertebrate classes (lamprey, ray, sheat-fish, carp, frog, triton, tortoise, hen, pigeon, rabbit, rat and monkey) was determined. In most cases a correlation was found between the level of nervous organization and the ganglioside content of brain. In fish and amphibian brain ganglioside concentration is half to one third that in mammalian brain. Ganglioside composition of higher vertebrate brains (mammals, birds and reptiles) has many similar features. Four main gangliosides with 1-3 NANA residues in their molecules–G₁ * * Nomenclature of Korey and Gonatas (1963 ): G₁ trisialyl-hexosaminyl-trihexosyl-ceramide; G₂ and G₃, disialyl-hexosaminyl-trihexosyl-ceramides; G₄ monosialyl-hexosaminyl-trihexosyl-ceramide.
, G₂, G₃ and G₄–constitute 80-90 per cent of total ganglioside NANA. Fractions G_2a ? ? G_o, tetrasialyl-hexosaminyl-trihexosyl-ceramide; G_2a disialyl-hexosaminyl-dihexosyl-ceramide; G₅, monosialyl-hexosaminyl-dihexosyl-ceramide.
G_o and G₅ are present in much lesser amounts. Species peculiarities in distribution of NANA among different fractions were noted. The brain gangliosides of lower vertebrates–fish and amphibia–are unusual in having a high proportion of polysialogangliosides, containing 4 and 5 NANA residues, and a lower content of monosialogangliosides. In ray brain a considerable part of gangliosides has a reduced carbohydrate chain.     

GANGLIOSIDE1−COMPOSITION OF BRAIN IN TAY-SACHS DISEASE: INCREASED AMOUNTS OF GD2 AND N-ACETYL-β-D-GALACTOSAMINYL GD1a GANGLIOSIDE

Abstract— The ganglioside composition of the brain of a patient with Tay-Sachs disease (TS-brain) was determined by a newly developed ganglioside-mapping procedure and compared with that of an age-matched control brain. GM2 ganglioside was the predominant component in TS-brain and the following gangliosides were also found, GM1, GD1a, GD1b and GT1 (major gangliosides in normal brain), and GM3, GD3, GD2 and GD1a-GAN (minor or undetectable components of normal brain). Individual gangliosides were isolated by column chromatography using a combination of DEAE-Sepharose, Iatrobeads and Silica Gel 60 and their structures were confirmed by comparing them with authentic standards using TLC, analysing their carbohydrate compositions by gas-liquid chromatography and cleaving them sequentially with glycosidases. The amounts of individual components were measured by quantitative densitometric scanning of the thin-layer plates. As a reflection of myelin breakdown, no sialosylgalactosyl ceramide was detectable in TS-brain. Although the total amounts of all gangliosides except GM2 in TS-brain were low, there were normal molar ratios of the main gangliosides in normal brain, that is, GM1, GD1a, GD1b and GT1. In comparison with the amount of GDla ganglioside, the amounts of GM2, GD2 and GD1a-GAN, which contain N-acetylgalactosamine as a terminal carbohydrate residue, were all elevated in TS-brain. The long chain bases of individual gangliosides contained both C-18 and C-20 sphingosine in different ratios and the ratio of C-20 to C-18 increased in the gangliosides in the order: GM2 < GM1 < GD1a < GD1a-GAN < GD1b < GT1 in both normal brain and TS-brain. In contrast, GD2 and GD3 gangliosides consisted mainly of C-18 sphingosine. The C-20 to C-18 ratios of individual gangliosides in the TS-brain were lower than those of age-matched control brain. Hexosaminidase from Turbo cornutus showed the same specific activity and K_m value in catalysing the cleavage of terminal N-acetylgalactosaminyl residues from GM2, GD2 and GD1a-GAN, suggesting that the brain gangliosides that increase in Tay-Sachs disease may be cleaved by the same enzyme.     

Tay-Sachs disease with atypical chronic course and limited brain storage: Alpha-locus hexosaminidase genetic compound

A 19-year-old Irish-Jewish male had a slow neurologic regression starting at age 4 1/2 years with stuttering. The chronic course resembled that of Spielmeyer-Vogt (juvenile ceroid-lipofuscinosis) disease. The brain was atrophic with neuronal losses and huge compound inclusions in the remaining neurons. Lipid NANA was within normal limits in gray and white matter and G_M2 gangliosides were moderately elevated at 11.5% lipid NANA. Beta-hexosaminidase A activity was lipid composition showed nonspecific abnormalities. Exhaustive tissue extraction ruled out the possibility of tightly bound gangliosides to account for the relatively low G_M2 ganglioside concentration. The extract contained unidentified chromogenic substances interfering with the resorcinol reaction. The similarly affected patient's sister lived to age 26 years and her brain was even more atrophic. No biochemical abnormality to account for progressive neuronal losses and relative lack of G_M2 ganglioside storage was found.Deceased.Special issue dedicated to Dr. Leon S. Wolfe.     

Exogenous glycosphingolipids suppress growth rate of transformed and untransformed 3T3 mouse cells

Gangliosides added to culture media reduced both the growth rate and saturation density of SV40-virus transformed and untransformed 3T3 cells. Monosialogangliosides were much more effective than disialogangliosides in inhibiting growth rate. These gangliosides caused little or no cell damage or significant morphological alteration of the individual cells. Trisialoganglioside markedly reduced growth rate but in some experiments also caused cell damage and lysis. The isolated carbohydrate moiety of the ganglioside G_Gtet1, the sialo-oligosaccharide galactopyranosyl-N-acetyl-galactosaminyl-(N-acetylneuraminyl)-galactosyl-glucose, did not inhibit growth of SV40 3T3 cells in culture. Ceramide alone was also ineffective as a growth inhibitor. However, the tetrahexosyl ceramide derived from the above ganglioside was equally as effective as the parent compound in retarding growth of SV40 3T3 cells. Similarly, mono-, di- and trihexosyl ceramides were also effective in inhibiting growth of these cells. Gangliosides added to the culture media were rapidly accumulated by cells, apparently at the plasma membrane. The accumulated ganglioside was not degraded by the cells. However, the accumulated ganglioside could be distinguished from gangliosides synthesized in vivo by the lability of the former to neuraminidase.     

STALOSYLGALACTOSYL CERAMTDE AS A SPECIFIC MARKER FOR HUMAN MYELIN AND OLIGODENDROGLIAL PERIKARYA: GANGLIOSIDES OF HUMAN MYELIN, OLIGODENDROGLIA AND NEURONS

Gangliosides were isolated from human brain myelin, oligodendroglia, and neurons. Quantitative analysis revealed the following ganglioside contents: myelin, 2.0; neurons, 1.3; and oligodendroglia, 0.35 μg ganglioside sialic acid per mg protein. Myclin had a relatively simple ganglioside pattern with G_M4 and G_M1 as the predominant ganglioside species. The ganglioside pattern of oligodendroglia was quite complex and it resembled that of whole white matter rather than that of myelin. A high concentration of G_M4 was found in oligodendroglial fractions in addition to G_M1, G_D1a, G_D1b, and G_T1b. The usually- minor brain gangliosides G_M3, G_M2, and G_M3 were also enriched in oligodendroglia. The neuronal ganglioside pattern was generally similar to the pattern of whole gray matter. Both neurons and whole gray matter contained very low amounts of G_M4. These results indicate that G_M4 is specifically localized in myelin and oligodendroglia of the CNS. Evidence is also presented that myelin, but not oligodendroglia, is the major reservoir of human white matter G_M1 and G_M4.     

Role of membrane gangliosides in the binding and action of bacterial toxins

Summary Gangliosides are complex glycosphingolipids that contain from one to several residues of sialic acid. They are present in the plasma membrane of vertebrate cells with their oligosaccharide chains exposed to the external environment. They have been implicated as cell surface receptors and several bacterial toxins have been shown to interact with them. Cholera toxin, which mediates its effects on cells by activating adenylate cyclase, bind with high affinity and specificity to ganglioside G_M1. Toxin-resistant cells which lack G_M1 can be sensitized to cholera toxin by treating them with G_M1. Cholera toxin specifically protects G_M1 from cell surface labeling procedures and only G_M1 is recovered when toxin-receptor complexes are isolated by immunoadsorption. These results clearly demonstrate that G_M1 is the specific and only receptor for cholera toxin. Although cholera toxin binds to G_M1 on the external side of the plasma membrane, it activates adenylate cyclase on the cytoplasmic side of the membrane by ADP-ribosylation of the regulatory component of the cyclase. G_M1 in addition to functioning as a binding site for the toxin appears to facilitate its transmembrane movement. The heat-labile enterotoxin ofE. coli is very similar to cholera toxin in both form and function and can also use G_M1 as a cell surface receptor. The potent neurotoxin, tetanus toxin, has a high affinity for gangliosides G_D1b and G_T1b and binds to neurons which contain these gangliosides. It is not yet clear whether these gangliosides are the physiological receptors for tetanus toxin. By applying the techniques that established G_M1 as the receptor for cholera toxin, the role of gangliosides as receptors for tetanus toxin as well as physiological effectors may be elucidated.     

Stimulation of platelet adhesion and activation by ganglioside GD3 adsorbed to plastic

Platelet interaction with gangliosides G_D3, G_M3, G_M1, G_D1a and G_T1b has been investigated. These gangliosides were previously identified in the vessel wall and ganglioside G_D3 was found to accumulate selectively in the intima of atherosclerotic vessels. Gangliosides were adsorbed to plastic and incubated with ⁵¹Cr-labeled platelets. The adhesion of gel-filtered platelets to ganglioside G_D3 was 3–4-times higher than to other immobilized gangliosides and to albumin-treated plastic. As was shown by scanning electron microscopy, G_D3 stimulated intensive spreading of adherent platelets and formation of surface-bound aggregates, while only single unspread platelets were present on the surfaces coated with other gangliosides. G_D3 isolated from milk and from human aorta possess the same stimulating activity. Platelet adhesion to G_D3 decreased significantly in the presence of the stable prostacyclin analogue, carbacyclin.     

Interaction of gangliosides with plasma low density lipoproteins

The role of gangliosides in the reception of low density lipoproteins (LDL) was studied using as targets mouse ascites hepatoma 22a (MAH) cells which bind LDL through a specific high affinity receptor. Low density lipoprotein binding and uptake by MAH cells decreased after brief treatment of the cells with neuraminidase to partially remove surface sialic acid residues. The LDL uptake capability of the neuraminidasetreated MAH cells was fully restored after incorporation of exogeneous G_M1- and G_D1a-gangliosides into the cell surface. In contrast, free (extracellular) gangliosides inhibited LDL uptake by native MAH cells. This inhibitory effect was seen at ganglioside concentrations corresponding to the ganglioside content of serum and was most pronounced with gangliosides whose sialic acids were linked to a terminal galactose residue (G_M3, G_D1a, G_T1b) but was smaller or absent with gangliosides whose sialic acids were attached to an internal galactose (G_M1, G_M2). The binding of gangliosides to LDL was structure and concentration dependent, saturable and trypsin sensitive. The LDL-ganglioside interaction was further investigated by steady state fluorescence spectroscopy. Changes in the LDL fluorescence polarization were observed with as little as 0.01 M concentrations of the gangliosides. The magnitude and nature of the effect depended on the type of ganglioside. We conclude that the LDL surface possesses sites recognizing specific carbohydrate sequences of glycoconjugates and that changes in the cell surface concentrations of sialic acids significantly modulate the LDL uptake. It is postulated that shedding of gangliosides into the blood stream may be a factor involved in regulation of cholesterol homeostasis.Abbreviations MAH mouse ascites hepatoma 22a - LDL low density lipoprotein - ASM anthrylvinyl-labeled sphingomyelin [N-12-(9-anthryl-trans-dodecanoyl-sphingosine-1-phosphocholine] - RITC rhodamine isothiocyanate. The designation of gangliosides follows the IUPAC-IUB recommendation [1]: G_M3, II³NeuAc-LacCer, II³-N-acetylneuraminosyllactosylceramide - G_M2 II³-NeuAc-GgOse₃Cer, II³-N-acetylneuraminosylgangliotriaosylceramide - G_M1 II³-NeuAc-GgOse₄Cer, II³-N-acetylneuraminosylgangliotetraosylceramide - G_D1a, II³ IV³(NeuAc)₂-GgOse₄Cer, II³, IV³-di(N-acetylneuraminosyl)gangliotetraosylceramide - G_T1b II³(NeuAc)₂, IV³ NeuAc-GgOse₄Cer, II³-di-N-acetylneuraminosyl, IV³-N-acetylneuraminosylgangliotetraosylceramide     

GLYCOSPHINGOLIPIDS IN FETAL TAY-SACHS DISEASE BRAIN AND LUNG CULTURES

Abstract— A study was undertaken of the glycosphingolipids in cell cultures derived from cerebellum of Tay-Sachs disease fetal brain in order to determine the suitability of such cell strains as a model for Tay-Sachs disease. The glycosphingolipids in the Tay-Sachs disease cultured cerebellar cells were compared with those found in normal cultured cerebellar cells, normal and Tay-Sachs cultured lung cells, and normal and Tay-Sachs fetal brain. The glycolipids were separated by TLC, then analyzed by GLC of the trimethylsilyi derivatives of the methylglycosides of the sugar moieties. In the cultured cerebellar lines, the predominant gangliosides were G_M2, G_M3, and G_D3. There was a 4-fold increase of G_M2 in the Tay-Sachs as compared with the normal line. Only G_M3 and G_D3 gangliosides were found in the Tay-Sachs and the normal fetal lung cell cultures. The major neutral glycosphingolipids in all of the cultured cells which were analyzed were glucosylceramide, lactosylceramide, digalactosyl-glucosylceramide, and globoside. When the Tay-Sachs cerebellar cells were labelled with [1-¹⁴C]gluco-samine, some radioactivity was observed in the trihexosylceramide band, indicating the presence of a small amount of a galactosamine-containing trihexosylceramide which may be asialo-G_M2 (G_A2). The trihexosylceramide in Tay-Sachs fetal brain was identified as G_A2 by GLC. Both Tay-Sachs and normal fetal brain gangliosides were more complex than those found in the cultured cells. Long chain fatty acids (C_24:0 and C_24;1) predominated in all of the glycosphingolipids of the Tay-Sachs and the normal cultured cerebellar cells. In contrast, the glycosphingolipids of Tay-Sachs and normal fetal brain contained mainly the shorter chain fatty acids (C₁₆:₀, C₁₈:₀, and C_18:1). The cerebrosides in both the Tay-Sachs and normal fetal brains were mainly glucosylceramide with only small amounts of the galactosylceramide which predominates in infant brain. Cultured cells from the fetal Tay-Sachs disease     

BODIPY-labeled ganglioside probes for membrane and biological studies

A series of new fluorescent ganglioside G_M1 derivatives bearing the residue of 4,4-difluoro-4-bora-3a,4a-diaza-s-indecene (BODIPY) either in the polar or nonpolar part of the molecule have been synthesized. Gangliosides G_M1 labeled with the residues of (4,4-difluoro-5-styryl-4-bora-3a,4a-diaza-s-indecenyl)-5-pentanoic (564/570-BODIPY-pentanoic) acid and (4,4-difluoro-5-butadienylphenyl-4-bora-3a,4a-diaza-s-indecenyl)-11-undecanoic (581/591-BODIPY-undecanoic) acid at the nonpolar part of the molecule or with the residue of (4,4-difluoro-5-butadienylphenyl-4-bora-3a,4a-diaza-s-indecenyl)-5-pentanoic (581/591-BODIPY-pentaoic) acid at the polar part of the molecule have been synthesized. The spectral characteristics of the resulting probes and their behavior in ganglioside G_M1 micelles and in sphingomyelin-cholesterol enriched bilayers containing BODIPY-FL-labeled gangliosides G_M1 have been studied. The localization of the label in the ganglioside molecule has been demonstrated to affect the efficiency of energy transfer in the case of the corresponding donor-acceptor pairs.     

ON THE COMPOSITION AND STRUCTURE OF INDIVIDUAL GANGLIOSIDES FROM THE BRAIN OF ELASMOBRANCHES

Gangliosides with a short carbohydrate chain: II³(NeuAc)₂-LacCer, II³(NeuAc)₂-GgOse₃Cer, II₃(NeuAc)₃-LacCer, II³NeuAc-LacCer, and II³NeuAC-GgOse₃ Cer, were found to be predominant in the brain of 8 species of cartilaginous fish, elasmobranches. N-acetylneuraminic acid was the only sialic acid found in these gangliosides, the N-glycolyl derivative being practically absent. 4-Sphingenine was shown to be the predominant sphingoid in elasmobranch brain gangliosides. The sequential enzymatic hydrolysis of II³(NeuAc)₂ -LacCer from shark and ray brain by acylneur-aminyl hydrolase (EC 3.2.1.18) and β-D-galactoside-galactohydrolase (EC 3.2.1.23), as well as permethylation studies, provide further evidence for the following structure of this major elasmobranch brain ganglioside:     

INCORPORATION OF [14C]N-ACETYL NEURAMINIC ACID INTO BRAIN GLYCOPROTEINS AND GANGLIOSIDES IN VIVO1

—Intracerebrally administered [¹⁴C]N-acetyl neuraminic acid was incorporated into brain glycoproteins and gangliosides. Incorporation into both classes of compounds was markedly inhibited by acetoxycycloheximide but incorporation into the soluble glycoproteins of the nerve-ending fraction was inhibited least of all. In contrast to glucosamine and fucose, a relatively small proportion of the injected [¹⁴C]NANA was incorporated.     

Topographic studies of gangliosides of intact synaptosomes from rat brain cortex

Gangliosides in the external surface of intact synaptosomes from rat brain cortex have been studied by oxidation of exposed galactose and galactosamine groups with galactose oxidase followed by reduction with labeled sodium borohydride. Purified synaptosomes were labeled, disrupted by osmotic shock, and the particulate components fractionated on diatrizoate to give four synaptosomal membrane fractions (A-D) and a mitochondrial pellet (E). Fractions A and B represent synaptosomal plasma membranes. When intact synaptosomes were labeled, the major portion of the total radioactivity incorporated into ganglioside fraction was found to be in G _M1 ³ species. With isolated membrane fractions little selectivity was seen: (1) more label was present compared to intact synaptosomes, and (2) zones corresponding to G_M2, G_M1, G_D1a, G_D1b were the major gangliosides labeled. The results confirm the conclusion that membrane fractions A and B are derived from the exposed synaptosome surface and also show that G_M1 is the major ganglioside species available for enzyme oxidation at the surface.     

Incorporation of N-Acetylmannosamine into Rat Brain Subcellular Gangliosides: Effect of Pentylenetetrazol-Induced Convulsions on Brain Gangliosides1

Abstract: The labeling pattern of the major individual gangliosides from the microsomal and synaptosomal fractions of rat brain was determined following intracerebral injection of the radioactive sialic acid precursor, N-acetylmannosamine. Microsomal gangliosides initially had a higher specific radioactivity than synaptosomal gangliosides, with both fractions reaching similar specific radioactivities 18 h after precursor injection. In both subcellular fractions, the polysialogangliosides G_T1b and G_Q1b were initially more highly labeled than all other gangliosides. With the establishment of the labeling pattern, the effect of the convulsant pentylenetetrazol on brain gangliosides was examined in detail. Significant decreases in radioactive label were noted in the polysialogangliosides, G_T1b and G_Q1b, from the synaptosomal and microsomal fractions of the convulsed animals. The decreases may be due to activation of the membrane-bound neuraminidase present with the gangliosides in neuronal tissue. Prior to experimentation, a methodology was developed to insure quantitative isolation of small amounts of ganglioside free of other lipids and water-soluble contaminants. Combination of this isolation procedure with quantitative densitometry of thin-layer chromatograms permits accurate distributional analyses for individual gangliosides. In applications involving radioactive gangliosides, the method allows the determination of both radioactivity and sialic acid distributions from the same thin-layer chromatogram.     

EFFECT OF LIGHT ON GANGLIOSIDES FROM CALF RETINA AND PHOTORECEPTORS

—The gangliosides of the whole calf retina and the rod outer segments have been analysed. This has been done in two functional states: before and after stimulation by light. After exposure to light no statistically significant change in the gangliosides of the whole retina was observed, but a 40 per cent increase in concentration was found in the rod outer segments. This difference was apparent only when using the same batch of rod outer segments. The major ganglioside in the whole calf retina is G_D3 which accounts for 46 per cent of the total. Three other gangliosides G_D1a, G_D1b and G_T1 are quantitatively important, each being between 12 and 16 per cent. G_Q1, G_M1, and G_M3 are minor constituents. In contrast to the chicken retina, G_M2 was not detected. The ganglioside N-acetylneuraminic acid of the rod outer segments accounts for only 1 per cent of the gangliosides of the whole retina. The composition of the gangliosides in the rod outer segments is essentially the same as that of the whole retina. No difference in the relative proportion of the gangliosides of either the rod outer segments or the whole retina was observed after exposure to light.     

GANGLIOSIDES OF PERIPHERAL NERVE MYELIN

—Gangliosides have been isolated from myelin obtained from three types of peripheral nerve: bovine spinal roots, bovine sciatic nerve and human sciatic nerve. Yields in most cases were 218–287 μg of lipid-bound sialic acid per g myelin, less than half that previously obtained from CNS myelin. Myelin accounted for approx 60% of total ganglioside present in whole spinal root. The human sample contained only N-acetylneuraminic acid but the two bovine preparations contained that as well as N-glycolylneuraminic acid; N-acetylglucosamine and N-acetylgalactosamine were both present in all three preparations. Sphingosine was the major long-chain base in each preparation while 4-eicosasphingenine (d20:1) comprised about 14% in the two bovine samples and 3% in the human sample. The major fatty acids in all preparations were 16:0, 18:0, 22:0, 24:0 and 24:1. Sialosylgalactosyl ceramide (G₇), a ganglioside characteristic of CNS myelin, was not detected in any of the PNS samples. The majority of gangliosides in bovine spinal root myelin were monosialo species, although the structures differed in some respects from those of CNS myelin. The molar concentration of lipid-bound sialic acid in PNS myelin is roughly equivalent to that of the P₁ basic protein.     

Preparation of the tritiated molecular forms of gangliosides with homogeneous long chain base composition

Gangliosides G_M2, G_M1 and G_D1b were radiolabelled at C-6 of the terminal galactose orN-acetylgalactosamine by the galactose oxidase/[³H]NaBH₄ method; gangliosides G_M2, G_M1, Fuc-G_M1 and G_D1a were radiolabelled at C-3 of the long chain base by the 2,3-dichloro-5,6-dicyanobenzoquinone/[³H]NaBH₄ method.By application of an original HPLC procedure, eight different molecular species were prepared from each labelled ganglioside. Each of these species was characterized by the presence of one of the following long chain bases:erythro C18 sphingosine,threo C18 sphingosine,erythro C18 sphinganine,threo C18 sphinganine,erythro C20 sphingosine,threo C20 sphingosine,erythro C20 sphinganine andthreo C20 sphinganine.From G_D1b only the species containing theerythro forms of long chain bases were obtained.The individual molecular species were more than 99% homogeneous and had a radiopurity better than 99%. The molecular species of the same ganglioside, radiolabelled at C-3 of the long chain base, had identical specific radioactivity, namely 1.17, 1.25, 0.85 and 1.28 Ci/mmol for G_M2, G_M1, Fuc-G_M1 and G_D1a respectively. The molecular species of the same ganglioside, radiolabelled at C-6 of terminal galactose orN-acetylgalactosamine, had similar specific radioactivity, namely 1.34–1.40, 1.44–1.51, 1.37–1.44 Ci/mmol for G_M2, G_M1 and G_D1b respectively.     

High-performance thin-layer chromatography and densitometric determination of brain ganglioside compositions of several species.

Improved resolution of complex brain ganglioside mixtures was achieved by high-performance thin-layer chromatography. The percentage distribution of individual gangliosides was then determined by direct densitometric seanning, employing a transmittance mode, of the resorcinol-positive spots on the plate. As little as 90 pmol (29 ng) of lipid-bound sialic acid could be detected with a good signal-to-noise ratio. A linear detector response was observed up to 3.0 μg of lipid-bound sialic acid. The brain white matter ganglioside patterns of eight animal species, including human, chimpanzee, monkey, chicken, bovine, sheep, and pig, were examined in detail. In addition, human brain gray matter, rat cerebral, rat brain gray matter, and rat cerebellar ganglioside patterns were also studied. Ganglioside G_M4 (G₇) was found to be one of the major components in primate and chicken brain white matter, but it represented only a minor ganglioside in other species. Other major gangliosides in all brain samples studied were G_M1, G_D1a, G_D1b, and G_T1b. G_M1 was more abundant in white matter than in gray matter. G_T1a, a recently discovered ganglioside species, was found in all species examined, but was most abundant in the rat cerebellum. The latter source also contained high proportions of G_T1b and G_Q1b.     

CEREBRAL LIPIDS IN A CASE OF SYSTEMIC GM2-GANGLIOSIDOSIS OF A LATE INFANTILE TYPE1

—Quantitative analyses performed on the lipids of cerebral grey matter from brains of a normal child and a child with Tay-Sachs (T-S) disease were compared with such analyses on the brain of a 6-year-old, non-Jewish male with systemic G_M2-gangliosidosis of a late infantile type (G_M2-LI). Analysis of gangliosides showed a 3·5-fold increase of total gangliosides in the G_M2-LI brain and a six-fold increase in the T-S brain, compared to normal brain. Both pathological brains had similar distribution patterns for gangliosides, with the G_M2-ganglioside component constituting more than 80 per cent of the total. Lipid components in the T-S brain were below normal values except for lecithin and cholesterol, while in the G_M2-LI brain there were increases in sulphatides, cerebrosides, sphingomyelin and cholesterol. Approximately twice as much ceramide trihexoside was present in the T-S brain as in the G_M2-LI brain, and none could be detected in the normal brain. The clinical, pathological and biochemical data support the conclusion that this case represents a new variant of systemic late-infantile gangliosidosis in which there is an accumulation of the G_M2-ganglioside like that in Tay-Sachs disease.     

Developmentally regulated O-acetylated sialoglycans in the central nervous system revealed by a new monoclonal antibody 493D4 recognizing a wide range of O-acetylated glycoconjugates

We have previously detected an alkali-labile and developmentally regulated antigen in rat embryonic cerebral cortex, which may be 9-O-acetylsialylated GT3 ganglioside (Hirabayashi Y, Hirota M, Suzuki Y, Matsumoto M, Obata K, Ando S (1989) Neurosci Lett 106:193-98). In this study we established a mouse monoclonal antibody, 493D4, that recognizes 9-O-acetyl GT3 ganglioside, but not non-O-acetyl gangliosides. This antibody also reacted with 9-O-acetyl GD3 to a much lesser extent. By using this antibody, we found that O-acetyl GT3 as well as O-acetyl GD3 were expressed strongly in fetal murine cerebral cortex and decreased to an undetectable level after birth. With the assistance of TLC-immunostaining using 493D4 together with Q-Sepharose column chromatography, O-acetyl gangliosides of bovine brain were purified and the structural analysis showed the presence of O-acetyl GD3, O-acetyl LD1, O-acetyl GD2 and O-acetyl GD1b in the adult brain as extremely minor components. Interestingly, the antibody 493D4 could detect O-acetyl sialoglycoproteins in rat brain tissues. One of the major immunoreactive proteins was shown to be synaptophysin, an integral membrane protein specifically present in synaptic vesicles. This monoclonal antibody was therefore useful for sensitive detection of both O-acetylated gangliosides and glycoproteins with O-acetylated sialic acids. This revised version was published online in November 2006 with corrections to the Cover Date.