Human medulloblastoma gangliosides

To establish a model system for the study of ganglioside metabolismof the human brain tumor, medulloblastoma, we have chemicallycharacterized the gangliosides of the Daoy cell line. Thesecells contain a high concentration of gangliosides (143 ±13 nmol LBSA/10⁸ cells). The major species have been structurallyconfirmed to be G_M2 (65.9%), G_M3 (13.0%), and G_Dla (10.3%).Isolation of individual gangliosides homogeneous in both carbohydrateand ceramide moieties by reversed-phase HPLC and analysis bynegative-ion fast atom bombardment collisionally activated dissociationtandem mass spectrometry have allowed us to unequivocally characterizeceramide structures. In the case of G_M2, 10 major ceramide subspecieswere identified: d18:1-hC16:0, d18:1-C16:0, d18:0-C16:0, d18:1-C18:0,d18:1-C20:0, d18:1-C22:0, d18:2-C24:1, d18: 1-C23:1, d18:1-C24:1,and d18:1-C24:0. Taken together with previous studies, thesefindings in human medullo-blastoma cells support the view thathigh expression and marked heterogeneity of ceramide structureare general characteristics of tumor gangliosides, moleculeswhich are shed by the tumor cells and which are biologicallyactive in vivo. medulloblastoma gangliosides ceramide structure HPLC mass spectrometry     

Different Ceramide Compositions of Gangliosides Between Human Motor and Sensory Nerves

Ganglioside analysis of human motor and sensory nerves revealed that ceramide compositions of sensory nerve GD1a, GD1b, and GM1 differed apparently from those in the motor nerve. These gangliosides from sensory nerve contained a large amount of long-chain fatty acids and d18:1 as a major long chain base. On the contrary, the motor nerve gangliosides contained C16-18 fatty acids and a large amount of d20:1 besides d18:1. Furthermore, these gangliosides were enriched more in the axon fraction than in the myelin fraction. LM1, which was a major ganglioside in myelin from human peripheral nerve, was composed of similar ceramide compositions in the two nerves. The present findings suggest that the characteristic ceramide species of nerve gangliosides may reflect in part properties of their own neurons.     

Isolation and characterization of major gangliosides from frog liver

Four major gangliosides isolated from frog liver were characterized by compositional analysis involving GLC and GC-MS, methylation analysis, chromium trioxide oxidation, and enzymatic hydrolysis. The results revealed that the most major ganglioside in the tissue was GM4 containing N-acetylneuraminic acid and the others were GM4 containing N-glycolylneuraminic acid, GD1a, and a fucosyl ganglioside which was tentatively assigned to be alpha-galactosyl alpha-fucosyl GM1. This is the first report describing the presence of GM4 containing N-glycolylneuraminic acid. The fatty acids in both GM4 were mainly alpha-hydroxylated, and those in the fucosyl ganglioside were exclusively nonhydroxy fatty acids. The GD1a contained both nonhydroxy and alpha-hydroxy fatty acids in a ratio of about 3:2. The predominant species were 22:0, 23:0, 24:0, and 24:1 in both species of the fatty acids. The long-chain bases of these four gangliosides consisted of C18-sphingosine and C18-phytosphingosine together with significant amounts of C16 to C19 dihydroxy and trihydroxy bases with iso and anteiso structures.     

New chemical trends in ganglioside research

A report is given of recent progress in the methodology for isolation of gangliosides from natural sources, for the preparation of molecular species of gangliosides homogeneous in both the oligosaccharide and ceramide portions of the molecule, for chemical manipulation and derivatization of gangliosides, and for the preparation of gangliosides radiolabelled in different parts of the molecule. Particular emphasis has been given to: high performance liquid chromatographic procedures capable to separate gangliosides on the basis of their oligosaccharide or ceramide moieties and yielding completely homogeneous compounds, that is gangliosides with a single oligosaccharide, a single long chain base and a single fatty acid; two-dimensional thin-layer chromatographic procedures, provided with a fully computerized quantification system, particularly suitable to identifying gangliosides containing alkali-labile linkages, including ganglioside lactones; chemical procedures of high yield for reducing gangliosides at the double bond of long chain base, for selective removal of the fatty acyl moiety and replacement with a novel fatty acid, and for the synthesis of ganglioside lactones; chemical procedures for inserting fluorescent, paramagnetic or photoreactive probes at the fatty acyl part of the ganglioside molecule; procedures for chemical isotopic radiolabelling of gangliosides at the level of sialic acid acetyl group and at the fatty acid moiety. Examples are provided evidencing the significance and potential use of a variety of ganglioside derivatives in the study of ganglioside metabolism and functional implications.     

Shedding of Gangliosides by Human Medulloblastoma Cells

Shedding of immunosuppressive gangliosides is an important characteristic of both experimental and human tumors. Using a medulloblastoma cell line, Daoy, with a very high ganglioside expression (141 ± 13 nmol/10⁸cells) and a well-characterized ganglioside complement, we have now studied ganglioside shedding by human brain tumor cells. Shedding of gangliosides, quantified by metabolic radiolabeling, was significant (169 pmol/10⁸cells/h) and was generalized with respect to the major ganglioside carbohydrate structures (G_M2, G_M3, and G_D1a). For each ganglioside, however, shedding was selective for ceramide structures containing shorter fatty acyl chains. Rapid and ceramide-selective shedding was confirmed in two additional human medulloblastoma cell lines, D341 Med and D283 Med (112 and 59 pmol/10⁸cells/h). Significant ganglioside shedding is therefore a common characteristic of human medulloblastoma cells and may influence the biological behavior of this tumor, in view of immunosuppressive and other biological properties of shed gangliosides.     

1H NMR Ganglioside Ceramide Resonance Region on the Differential Diagnosis of Low and High Malignancy of Brain Gliomas

1. The high-resolution ¹H NMR (MRS) spectra of human brain tumor homogenates revealed a broad resonance at 5.3–5.4 ppm in glioblastoma multiforme (N = 16) and brain metastases (N = 2). The broad resonance was identified as ceramide, a sphingosine–fatty acid combination portion of ganglioside, indicating an elevated abundance of monounsaturated fatty acids. GLC analysis of gangliosides in the highly malignant glioblastoma multiforme revealed that the elevated monounsaturated fatty acid is oleic acid (C18:1). The resonance at 5.3–5.4 ppm region was not detectable in normal human brain (N = 2), in meningiomas (N = 2), or in low-grade astrocytomas (N = 12). In normal human brain the abundance of monounsaturated fatty acid is minimal.2. This investigation was made possible because the method of producing homogenate resulted in (i) no loss of lipids during the process and (ii) a well-homogenised sample, with (iii) no loss in chemical integrity.3. The properties of tumor gangliosides include antigenic specificity and immunosuppresive activity and the ceramide, a sphingosine–fatty acid combination, noticeably influences the ganglioside immunosuppressive activity.4. The observation of ¹H NMR ceramide resonance in high-malignant brain tumors emphasizes the dramatic role of aberrant gangliosides and ceramide precursors on the grade of malignancy and invasiveness.5. Further insight into the specific nature of the ceramide portion of gangliosides in grading the malignancy of brain tumors should be investigated further.     

Structural characterization of gangliosides isolated from mullet milt using electrospray ionization-tandem mass spectrometry.

Electrospray ionization (ESI) coupled with tandem mass spectrometry has been used in conjunction with microwave-mediated saponification, periodate oxidation, and clostridial sialidase hydrolysis to enable detailed structural characterization of gangliosides and their derivatives present in mullet milt. The gangliosides extracted from mullet milt were determined to be GM3, GM3 lactone, GM3 methyl ester, and 9-O-acetyl GM3. For the major ganglioside GM3 and all GM3 derivatives, the ceramide composition was revealed to be C18:1/C16:0. GM3 with a C18:0/C16:0 ceramide was also found as a minor ganglioside. Both the ganglioside intramolecular ester and the ganglioside methyl ester (lacking carboxylic acid groups) showed dominant chloride attachment peaks (M + Cl)- in negative ion ESI-MS in addition to low intensity peaks corresponding to (M-H)-. GM3 and O-acetyl GM3 bearing carboxylic acid functions showed only (M-H)-. In positive ion ESI, GM3 and O-acetyl GM3 revealed (M + 2Na-H)+ peaks in addition to (M + Na)+, indicating free exchange of the carboxylic acid proton with a sodium cation, while the ganglioside intramolecular ester and ganglioside methyl ester with no acidic protons yielded only (M + Na)+. The strategy of employing ESI-MS to detect products of established wet chemical reactions represents a general approach for elucidation of ganglioside structural details.     

Isolation and structural elucidation of a novel type of ganglioside, deaminated neuraminic acid (KDN)-containing glycosphingolipid, from rainbow trout sperm. The first example of the natural occurrence of KDN-ganglioside, (KDN)GM3

Rainbow trout sperm contained almost exclusively monoanionic ganglioside fraction as a major acidic glycosphingolipid. Two monoacidic gangliosides were isolated and purified in this study and designated as sperm ganglioside 1 and 2 (sg-1 and sg-2). The two gangliosides, sg-1 and sg-2, contained the same neutral sugars, galactose and glucose in molar ratio of 1:1 and no GalNAc except for the presence of N-acetyl-neuraminic acid (NeuAc) in sg-1 and deaminated neuraminic acid (KDN; 2-keto-3-deoxy-D-glycero-D-galacto-nononic acid) in sg-2. The complete structures of these gangliosides were determined by a combination of methylation analysis, fast atom bombardment mass spectrometry, 400-MHz one- and two-dimensional 1H nuclear magnetic resonance spectroscopy, fatty acid analysis, and endoglycoceramidase digestion NeuAc alpha 2----3Gal beta 1----4Glc beta 1----Cer sg-1 [(NeuAc)GM3] KDN alpha 2----3Gal beta 1----4Glc beta 1----Cer sg-2 [(KDN)GM3] where, for both sg-1 and sg-2, the ceramide moieties (Cer) were found to be made up of 4-sphingenine and mainly C16:0 fatty acid (palmitate; 95%) with a minor amount of C24:1 fatty acyl chain (nervonate, 5%). The structure of sg-2 is novel and represents the first example of a new class of gangliosides, i.e. KDN-gangliosides.     

Age-Related Changes in the Ceramide Composition of the Major Gangliosides Present in Rat Brain Subcellular Fractions Enriched in Plasma Membranes of Neuronal and Myelin Origin

Abstract: Age-related changes of the ceramide composition of gangliosides were studied in the synaptosomal and myelin fractions from rat brain, carrying plasma membranes of neuronal and glial origin, respectively. The five major gangliosides (GM1, GD1 a, GD1 b, GT1 b, and GQ1 b) present in these fractions were separated and quantitated by normal-phase HPLC. Each ganglioside was then fractionated by reverse-phase HPLC into the molecular species carrying a single long-chain base (LCB). The largely preponderant LCBs in the synaptosomal and myelin fractions were the C18:1 and C20:1. The content of C20.1 LCB, generally low at 1 month, increased with age in all analyzed gangliosides and in all subcellular fractions and was greater in the "b series" than in the "a series" gangliosides. Remarkably, GM1 was the only ganglioside where the proportion of LCB 20:1 was higher in the synaptosomal fraction than in the myelin fraction. The fatty acid composition of the C18:1 or C20:1 LCB species of the different gangliosides in the synaptosomal and myelin fractions did not undergo appreciable changes with age. Stearic acid was largely predominant in all the gangliosides of the synaptosomal fraction, more in the C18:1 than in the C20:1 LCB species (80–90% vs. 60–70%). The gangliosides of the myelin fraction were characterized by a lower content of 18:0 and a much higher content of 16:0 and 18:1 fatty acids than those of the synaptosomal fraction. Thus, the ceramide composition is different in the gangliosides of neuronal and myelin origin and appears to be subjected to an age-related control.     

A novel approach for ganglioside structural analysis based on electrospray multiple-stage mass spectrometry.

A powerful method for detailed structural analysis based on electrospray ionization high-capacity ion-trap multiple-stage mass spectrometry (MS) is for the first time introduced in glycolipidomics. The method was optimized for accurate structural elucidation of human brain gangliosides and specifically applied to normal adult human hippocampus-associated structures. The multiple-stage MS experiments reported here allowed for a complete structural characterization of the oligosaccharide moiety of a GM1 ganglioside species. This was achieved by elucidating the sequence and identification of the GM1a structural isomer from the sialic acid attachment site at the neutral oligosaccharide chain. Moreover, the determination of the d18:1/18:0 sphingoid base/fatty acid composition of the ceramide moiety could be confirmed by this method. The novel protocol developed here proves high potential for rapid, reliable, and reproducible investigation of complex lipid-linked carbohydrates such as polysialylated gangliosides or species carrying some other groups that easily cleave off.     

Synthesis of lysogangliosides

The synthesis of gangliosides GM3, GM2, GM1, and GD1a solely lacking the fatty acid moiety, and thus called lysogangliosides in analogy to lysophospholipids, is described. Since a selective elimination of the fatty acid residue has not been achieved as yet, the gangliosides were first subjected to alkaline hydrolysis. By this procedure the fatty acyl as well as the acetyl groups of the sialic acid residue(s) were completely removed. The acetamido group of the N-acetylgalactosamine moiety of the gangliosides GM2, GM1, and GD1a was very little (congruent to 10%) hydrolyzed. In a two-phase system composed of water and ether, the selective protection of the sphingoid amino group was accomplished with a hydrophobic protective group (9-fluorenylmethoxycarbonyl). Lysogangliosides were obtained after re-N-acetylation of the sialooligosaccharide amino group(s) followed by removal of the protecting group. The overall yield was about 30%. The structures of the lysogangliosides were confirmed by chemical analysis as well as negative ion FAB mass spectrometry and 1H NMR spectroscopy. By simple re-N-acylation of lysogangliosides with any labeled fatty acid, labeled gangliosides are now obtainable that are identical with their parent gangliosides except for their labeled fatty acid residue. This has been demonstrated by the synthesis of GM1 with a [1-13C]palmitic acid moiety in its ceramide portion. If desired, double-labeled gangliosides may be obtained by use of labeled acetic anhydride in the synthesis of the lysogangliosides.     

Alteration of ganglioside synthesis by GM3 synthase knockout in murine embryonic fibroblasts

To probe the functions of membrane gangliosides, the availability of ganglioside-depleted cells would be a valuable resource. To attempt to identify a useful genetic model of ganglioside depletion, we assessed ganglioside metabolism in murine GM3 synthase (GM3S)-/- knockout primary embryonic fibroblasts (MEF), because normal fibroblast gangliosides (GM3, GM2, GM1, and GD1a), all downstream products of GM3S, should be absent. We found that heterozygote MEF (GM3S+/-) did have a 36% reduced content of qualitatively normal gangliosides (7.0+/-0.8 nmol LBSA/mg cell protein; control: 11+/-1.6 nmol). However, two unexpected findings characterized the homozygous (GM3-/-) MEF. Despite complete knockout of GM3S, (i) GM3-/- MEF retained substantial ganglioside content (21% of normal or 2.3+/-1.1 nmol) and (ii) these gangliosides were entirely different from those of wild type MEF by HPTLC. Mass spectrometry identified them as GM1b, GalNAc-GM1b, and GD1alpha, containing both N-acetyl and N-glycolylneuraminic acid and diverse ceramide structures. All are products of the 0 pathway of ganglioside synthesis, not normally expressed in fibroblasts. The results suggest that complete, but not partial, inhibition of GM3 synthesis results in robust activation of an alternate pathway that may compensate for the complete absence of the products of GM3S.     

Changes of the human liver GM3 ganglioside molecular species during aging.

Sialosyl-lactosylceramide, GM3, is the major ganglioside of human liver, where it constitutes more than 90% of the total lipid-bound sialic acid. When analyzed by thin-layer chromatography, human liver GM3 migrates as two main spots. They are representative of ganglioside molecular species which differ in the acyl moiety. The faster running spot is mainly composed of molecular species with non-hydroxylated C22-C24 acyl chains; the other contains mainly molecular species bearing non-hydroxylated C16-C18 and alpha-hydroxylated C16-C24 acyl chains. In this study the content of the two GM3 molecular species groups was investigated in 31 subjects ranging from 19 to 85 years of age. By thin-layer chromatography we observed that the group of molecular species containing non-hydroxylated C22-C24 acyl chains, decreased linearly with subject age, while that of non-hydroxylated C16-C18 acyl chains and hydroxylated C16-C24 acyl chains increased linearly. Fast-atom-bombardment mass spectrometry performed on seven samples from subjects ranging from 21 to 78 years of age demonstrated that the age-dependent increase of the lower spot is caused by an increase in the hydroxylated fatty acid form of GM3, the content of non-hydroxylated C16-C18 fatty acid species remaining constant with age.     

Purification and structural characterization of de-N-acetylated form of GD3 ganglioside present in human melanoma tumors

The presence of gangliosides containing de-N-acetylated sialic acids in human tissues has been so far shown by using mouse monoclonal antibodies specific for the de-N-acetylated forms, but the isolation and chemical characterization of such compounds have not yet been performed. Since indirect evidence suggested that de-N-acetylGD3 ganglioside could be present in human melanoma tumors, we analyzed the gangliosides purified from a 500-g pool of those tumors. The de-N-acetylGD3 that was found to migrate just below GD2 in thin-layer chromatography was isolated from the disialogangliosides by high-pressure liquid chromatography using the specific antibody SGR37 to monitor the elution. The amount of antigen was found to be 320 ng per gram of fresh tumor or 0.1% of total gangliosides. Gas chromatography-mass spectrometry analysis of the antibody-positive ganglioside showed that sialic acids were formed of one molecule of N-acetylneuraminic acid and one molecule of neuraminic acid. Radioactive re-N-acetylation of the antigen yielded a GD3-like ganglioside with the radioactive label on the external sialic acid. The constitutive fatty acids were found to differ markedly from those of GD3 and 9-O-acetylGD3 isolated from the same pool of tumors. The major fatty acids were C16:0 and C18:0 in de-N-acetylGD3, whereas GD3 and its 9-O-acetylated derivative contained a large amount of C24:1. These data show that de-N-acetylGD3 ganglioside is indeed present in human melanoma tumors, and the fatty acid content suggests the existence of a de-N-acetylase mostly active on the molecular species of gangliosides with short-chain fatty acids.     

Glycosphingolipid specificity of the human sulfatide activator protein

The interaction of the sulfatide activator protein with different glycosphingolipids have been studied in detail. The following findings were made. 1. The sulfatide activator protein forms water-soluble complexes with sulfatides [Fischer, G. and Jatzkewitz, H. (1977) Hoppe-Seyler's Z. Physiol. Chem. 356, 6588-6591] and various other glycospingolipids. 2. In the absence of degrading enzymes the activator protein acts in vitro as a glycosphingolipid transfer protein, transporting glycosphingolipids from donor to acceptor liposomes. Lipids having less than three hexoses, e.g. galactosylceramide, sulfatide and ganglioside GM3 were transferred at very slow rates, whereas complex lipids such as gangliosides GM2, GM1 and GD1a were transferred much faster than the former. The transfer rate increased with increasing length of the carbohydrate chain of the lipid molecules. 3. Both the acyl residue in the ceramide moiety and the nature of the carbohydrate chain are significant for recognition of the glycosphingolipids by the sulfatide activator protein. Apparently, both residues serve as an anchor and the longer they are the better they are recognized by the protein. 4. In the absence of activator protein, degradation rates of sulfatide derivatives by arylsulfatase A, and of ganglioside GM1 derivatives by beta-galactosidase, increase with decreasing length of acyl residues in their hydrophobic ceramide moiety. Addition of activator protein stimulates the degradation of only those GM1 and sulfatide derivatives that have long-chain fatty acids in their hydrophobic ceramide anchor.     

Preparation of GM1 ganglioside molecular species having homogeneous fatty acid and long chain base moieties

A new procedure is described for preparing the molecular species of GM1 ganglioside that carry a single fatty acid (myristic (C14:0), stearic (C18:0), arachidic (C20:0) or lignoceric (C24:0) acid) and a single long chain base (C18 or C20 sphingosine, C18 or C20 sphinganine, each of them in natural 3D(+)erythro or unnatural 3L(-)threo form). The procedure consisted of the following steps: a) alkaline hydrolysis of GM1 ganglioside in the presence of tetramethylammonium hydroxide, which produces de-N-acylation of the ceramide and de-N-acetylation of the sialic acid residue; b) specific re-N-acylation at the long chain base amino group with a new fatty acid (myristic, stearic, arachidic, or lignoceric) in the presence of 1-(3-dimethylaminopropyl)-3-ethyl-carbodiimide hydrochloride; and c) final re-N-acetylation at the level of the sialic acid residue. GM1 ganglioside molecular species, completely homogeneous in the ceramide portion, were prepared by reversed phase high performance liquid chromatography. The GM1 ganglioside molecular species were analyzed for saccharide, fatty acid, and long chain base composition by chemical and spectrometric analyses. Using a combination of the two procedures, 32 different molecular species of GM1 ganglioside, over 99% homogeneous, have been prepared.     

Tissue-specific expression of GM3(NeuGc) and GD3(NeuGc) in epithelial cells of the small intestine of strains of inbred rats. Absence of NeuGc in intestine and presence in kidney gangliosides of brown Norway and spontaneously hypertensive rats

The ganglioside composition of the epithelial cells of the small intestine was investigated in 15 strains of inbred rats. Most of these strains had GM3 as the only detectable ganglioside. In addition to GM3, small amounts of GD3 were found in four strains, AVN, BN, DA, and LE. The fatty acid content of the ceramide portion was composed of a large, although variable, percentage of 2-hydroxy fatty acids. The sphingoid base was always C18-4D-hydroxysphinganine. The highly prominent sialic acid was N-glycolylneuraminic acid (NeuGc) in most strains. However in two strains, Brown Norway (BN) and spontaneously hypertensive rats (SHR), NeuAc was the only sialic acid of the gangliosides of the intestinal epithelium. The analysis of the ganglioside composition of the epithelium of the small intestine of the first generation hybrids of SHR with DA and BN, respectively, demonstrated that the expressions of GM3 (NeuGc) and GD3 were genetically transmitted as dominant traits and that BN and SHR were likely to carry the same deficient gene that led to the expression of GM3(NeuAc) instead of GM3(NeuGc) in the small intestine. For comparison, the sialic acid composition of kidney gangliosides was analyzed in some strains. 21-23% of the kidney gangliosides was GM3(NeuGc) in all tested strains, including BN and SHR. Therefore, the ganglioside composition of the intestinal epithelium could vary in the rat species, and the defect of N-glycolylneuraminic acid was not only strain-specific but also occurred in a tissue-specific way among strains of inbred rats.     

Gangliosides of dogfish (Squalus acanthias) brain

Eighteen gangliosides were isolated from dogfish (Squalus acanthias) brain, and their structures and compositions were determined by methylation analysis, enzymatic hydrolysis and partial hydrolysis with mild acid. Tetra- and pentasialogangliosides were also analysed by liquid secondary ion mass spectrometry. The dogfish brain gangliosides were characterized by a variety of molecular species. The most abundant ganglioside was GM2 (22.8% of the total sialic acid content), followed by GQ1c (16.0%), GP1c (13.4%), and GD2 (12.5%). The abundance of gangliosides containing a gangliotriaose core (GM2 and GD2), and c-series polysialogangliosides (GQ1c and GP1c) was a prominent feature of dogfish brain, differing from the brain gangliosides of teleosts and other vertebrates. A battery of trisialogangliosides was also found. A ganglioside which had an a- and -series hybrid-structure (IV³NeuAc,III⁶NeuAc,II³NeuAc-Gg₄Cer) comprised 1.4% of the total. The major fatty acids comprised 16:0, 18:0, 18:1, 22:1 and 24:1. The gangliosides with a gangliotriaose core predominantly contained 22:1. Sphinganine and 4-sphingenine comprised the long-chain bases.     

Gangliosides of murine T lymphocyte subpopulations

Gangliosides from murine T lymphoblasts were analyzed by high-performance thin-layer chromatography followed by in situ neuraminidase treatment and immunostaining of the resulting asialogangliosides and compared with those from thymocytes and cloned T lymphocytes with defined functions. The ganglioside IVNeuGc/Ac-GgOse5Cer (GalNAc-GM1b), a marker for T lymphoblasts [Müthing, J., Egge, H., Kniep, B., & Mühlradt, P. F. (1987) Eur. J. Biochem. 163, 407-416], was found only in small amounts as the N-acetylated species in gangliosides from thymocytes and a cytolytic T cell clone. Two helper clones expressed this ganglioside like T blasts. The structures of the two major disialogangliosides from T blasts, IVNeuAc,IIINeuAc-GgOse4Cer (GD1 alpha type) with C24:0/24:1 and C16:0 fatty acids, were elucidated by neuraminidase treatment and immunostaining and by fast atom bombardment mass spectrometry. Gangliosides of this type were detected in thymocytes only in minor amounts, whereas GM1b-type gangliosides prevailed in cells from this organ. Analysis of the T lymphoblast gangliosides from six genetically unrelated mouse strains showed that terminally sialylated GgOse4Cer (GM1b), IVNeuAc-GgOse5Cer (GalNAc-GM1b), and IVNeuAc,IIINeuAc-GgOse4Cer (GD1 alpha) were conserved structures in all strains examined. We conclude that maturation or stimulation of T cells may be correlated with elongation of a common GM1b-type precursor structure resulting in GalNAc-GM1b or GD1 alpha-type gangliosides.