Distribution of molecular species of sphingomyelins in different parts of bovine digestive tract.

Sphingomyelins were isolated from mucosal layers of bovine rennet stomach, duodenum, jejunoileum, and colon ascendens. The ceramides obtained after phospholipase degradation were characterized by thin-layer chromatography, mass spectrometry, and gas-liquid chromatography. The main ceramide group from all regions consisted of dihydroxy long-chain bases and normal fatty acids. Sphingosine was the predominant base in all these fractions, and only in rennet stomach were smaller amounts of the C17 and C20 homologs present. Normal saturated C16, C18, C22, and C24 fatty acids were most abundant. In rennet stomach there was in addition a ceramide group having dihydroxy long-chain bases in combination with hydroxy fatty acids. Sphingosine was the predominant long-chain base and the fatty acids were 2-hydroxy C16, C22, C23, and C24. From jejunoileum three minor ceramide fractions were isolated; these consisted of phytosphingosine and normal fatty acids C22-C24), sphingosine and 2-hydroxy fatty acids (C16-C24), and phytosphingosine and 2-hydroxy fatty acids (C22-C24), respectively. No branched paraffin chains were found in significant amounts. Sphingomyelins with trihydroxy long-chain bases and 2-hydroxy fatty acids found in jejunoileum were also detected in bovine kidney and have not been demonstrated before. These sphingomyelins from both kidney and jejunoileum showed a preferential combination of trihydroxy bases and fatty acids with very long chains (C22-C24).     

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.     

Main structures of the Forssman glycolipid hapten and a Leb-like glycolipid of dog small intestine, as revealed by mass spectrometry. Difference in ceramide structure related to tissue localization.

Two glycolipids of dog small intestine, one with Forssman activity and one with Leb-like activity, have been characterized by mass spectrometry of methylated, and methylated and reduced (LiAlH4) derivatives. The Forssman glycolipid was conclusively shown to be a pentaglycosylceramide with the carbohydrate sequence hexosamine-hexosamine-hexose-hexose-hexose-ceramide, and with sphingosine (dihydroxy base) as major long-chain base and normal fatty acids as the only fatty acids. The Leb-like glycolipid was a hexaglycosyl-ceramide with sequence fucose-hexose-[fucose-] hexosamine-hexose-hexose-ceramide and with phytosphingosine (trihydroxy base) as major long-chain base and only 2-hydroxy fatty acids as fatty acids. The difference of two hydroxy groups in the ceramide between the two glycolipids may be related to a different tissue localization. As shown by immunofluorescense study the Forssman activity was associated with the lamina propria and the Leb-like activity to the glandular epithelium of dog small intestine.     

Sphingophosphonolipid molecular species from edible mollusks and a jellyfish

The goal of this study is to supplement the composition and nature of sphingophosphonolipids diversity from edible mollusks (Mytilus galloprovincialis, Eobania vermiculata) and from jellyfish Pelagia noctiluca, organisms rich in phosphonolipids. M. galloprovincialis contained a major ceramide 2-aminoethylphosphonate (CAEP-IM) and a minor ceramide that was detected chromatographically as the methyl analog (CAEP-IIM). In CAEP-IM, saturated fatty acids (FA) of 14, 16 and 18 carbons amounted to 68.8%; also 52.5% dihydroxy bases were detected. On thin layer chromatography, the Rf for CAEP-IIM was smaller than the Rf for CAEP-IM because of an increase of 22.0% in 2OH-16:0 FA, plus 29.2% trihydroxy bases (phytosphingosine). Similarly, a ceramide 2-methylaminoethylphosphonate (CAEP-IIE, 1.5% of phospholipids) was quantitated in Eobania (apart from the previously reported major CAEP, 7.6%). In CAEP-IIE, saturated and hydroxy FA of 14, 16 and 18 carbons amounted to 37.0 and 37.8%; 29.1% dihydroxy and 23.0% trihydroxy bases were detected in the same molecule. Eobania's unsaturated FA percentages (total lipids: 66.3, polar: 47.5, neutral: 59.0) were similar to those previously found for other land snails. A suite of two minor CAEP (CAEP-IIP, CAEP-IIIP) was quantitated in Pelagia at 2.0 and 1.3% of phospholipids (apart from the previously reported major CAEP, 21.0%) identified chromatographically as methyl analogs. In CAEP-IIP, saturated FA of 14, 16, 18 and 19 carbons amounted to 56.0%; 12.6% dihydroxy and 34.1% trihydroxy bases were also detected in CAEP-IIP. The Rf CAEP-IIIP相似文献   

Characterization and comparison of lipids in different squid nervous tissues

We have studied the lipid composition of brain (optic and cerebral lobes), stellate ganglia and fin nerves of the squid. Cholesterol, phosphatidylethanolamine and phosphatidylcholine were the major lipids in these nervous tissues. Phosphatidylethanolamine contained about 3% of its amount in [corrected] plasmalogen form. Phosphatidylserine and -inositol, sphingomyelin and ceramide 2-aminoethylphosphonate were also present in significant amounts. In addition, cardiolipin and free fatty acids were detected in brain (each 2-3% of total lipids) and stellate ganglia (about 1% each), but not in fin nerves. Phosphatidylethanolamine, phosphatidylserine and phosphatidylinositol from brain contained large amounts of polyunsaturated fatty acids, namely 20:4, 20:5 and 22:6 in the n-3 family. On the other hand, phosphatidylcholine, cardiolipin, and sphingomyelin, and ceramide 2-aminoethylphosphonate contained only saturated or monounsaturated C16-C18 fatty acids. The aldehyde moieties of ethanolamine plasmalogen were also C16-C18 saturated or monounsaturated. These lipid compositions are compared with those in other invertebrate nervous systems.     

Free ceramide, sphingomyelin, and glucosylceramide of isolated rat intestinal cells.

Free ceramide, glucosylceramide, and sphingomyelin were isolated from mature cells of adult rat small intestine. Free ceramide and ceramide cleaved from sphingomyelin by enzymatic hydrolysis were fractionated by thin-layer chromatography on borate-impregnated silica gel plates. Sphingoid bases were characterized by gas-liquid chromatography of aldehydes formed upon periodate oxidation. Fatty acids were quantified as methyl esters. Ceramide structures were confirmed by direct-inlet mass spectrometry. Free ceramide was found to contain two major long-chain bases in nearly equal quantity: sphingosine, mainly linked to palmitic acid, and 4D-hydroxysphinganine associated with C20 to C24 fatty acids, 22% being hydroxylated. Sphinganine occurred as a minor component linked to nonhydroxy fatty acids. Sphingomyelin contained the three long-chain bases and 63% of its ceramide was N-palmitoyl-sphingosine. Mass spectrometry of glucosylceramide confirmed 4D-hydroxyshingamine as the major sphingoid base associated preferentially with longer chain hydroxy fatty acids.     

The structure and distribution of ceramide aminoethylphosphonates in the oyster (Ostrea gigas).

1. Ceramide aminoethylphosphonate was isolated from the adductor, gills, mantle and viscera of oysters. 2. After drastic acid hydrolysis of the lipid, aminoethylphosphonic acid was the only water-soluble carbon-phosphorous compound detected. 3. The main fatty acids of ceramide aminoethylphosphonates were hexadecanoic acid (77-90%) and 2-hydroxy hexadecanoic acid (13-15%). 4. Hexadeca-4-sphingenine, octadeca-4-sphingenine and octadeca-4,8-sphingadienine were identified as the major long chain base components. However, the ratio of the three bases was characteristic for each tissue; the adductor muscle contains primarily hexadeca-4-sphingenine, and the viscera, octadeca-4,8-sphingadienine. The gills and mantle contain the three bases in approximately equal concentration. 5. The main molecular species in the adductor muscle was hexadecanoyl-hexadeca-4-sphingenyl 2-aminoethylphosphonate, while in the viscera hexade-canoyl-octadeca-4,8-sphingenyl 2-aminoethylphosphonate predominated.     

Characterization of neutral sphingolipids and gangliosides from chicken liver

The neutral sphingolipids and gangliosides were isolated from 62- and 63-day-old chicken livers and characterized. The total concentration of neutral sphingolipids was 59 nmol/g of liver, and that of gangliosides was 330 nmol/g of liver. The major neutral sphingolipids were free ceramide, galactosylceramide, glucosylceramide, lactosylceramide, galabiosylceramide, and Forssman glycolipid. Galactosylceramide was the most abundant and free ceramide was the second most abundant. The major gangliosides were sialosylgalactosylceramide (GM4) and sialosyllactosylceramide (GM3), each of which contained only N-acetylneuraminic acid as a sialic acid. Sphingosine (d18:1) was a major long-chain base in all the sphingolipids. Considerable amounts of 2-hydroxy fatty acids were present in free ceramide, galactosylceramide, and GM4.     

Gas--liquid chromatography-mass spectrometry of synthetic ceramides

Two series of ceramides with either sphingosine (sphing-4-enine) or sphinganine as base and with one of the saturated fatty acids C(16), C(18), C(20), C(22), C(24), C(26), or oleic acid were analyzed as the 1,3-di-O-trimethylsilyl ether derivatives by gas chromatography-mass spectrometry. The fragments formed on electron impact can be divided into three main groups, namely "molecular weight fragments," "long-chain base fragments," and "fatty acid fragments." The m/e values of these fragments can be used to determine unequivocally the structures of the long-chain base and fatty acid of a ceramide derived from a sphingolipid.     

The lipid composition of the electric organ of the ray, Torpedo marmorata, with specific reference to sulfatides and Na+-K+-ATPase.

The lipids from the electric organ of the ray, Torpedo marmorata, have been isolated and characterized. The major lipids were cholesterol, choline phospholipids, ethanolamine phospholipids, and sphingomyelins. The major fatty acids of ethanolamine phospholipids were 18:1, 18:0, 22:6, and 20:4. More than 50% of the acids in choline phospholipids were 16:0. The sphingomyelins consisted of five major ceramide species, all with sphingosine and the fatty acids 14:0, 15:0, 16:0, 22:1, and 24:1. The fatty acid 15:0 was mostly branched (n-2), a fatty acid earlier identified in sphingomyelins of the rectal gland of spiny dogfish. All long-chain bases were dihydroxy bases with a small percentage of branched chains. Sulfatides (cerebroside sulfate) made up the largest glycolipid fraction. The polar moiety wase galactose-3-sulfate. The fatty acids were normal and 2-hydroxy; the homologue 24:1 was the most abundant in both types of fatty acids. Most fatty acids were higher homologues of mono-unsaturated acids, but normal 18:0 fatty acid was also found. The long-chain bases were both dihydroxy and trihydroxy, with very small amounts of branched chains. The two major ceramide species of sulfatides were sphingosine combined with normal and hydroxy 24:1 fatty acids, respectively. Smaller amounts of trihydroxy base (18:0) were found linked to hydroxy 24:1 fatty acid, but not to its normal homologue. The cerebrosides contained the two major species mentioned above but lacked the trihydroxy base-hydroxy fatty acid species. The ratio of the activity of Na+-K+-dependent ATPase (EC 3.6.1.3) and the concentration of sulfatides was similar to ratios found for other tissues with normal and increased Na+ and K+ transporting capacity. The significance of this finding is discussed.     

Characterization of neutral sphingolipids from chicken erythrocytes

The neutral sphingolipids from chicken erythrocytes were characterized. The total concentration of neutral sphingolipids was found to be 480 nmol/g of dry stroma. They were isolated and purified by droplet counter-current chromatography, Iatrobeads column chromatography, and preparative thin-layer chromatography. The major neutral sphingolipids were free ceramide, ceramide monohexoside, ceramide dihexoside, and ceramide pentahexoside, which represented 43%, 23.5%, 10.0%, and 3.6% of the long chain bases, respectively. Thus, free ceramide was the most abundant neutral sphingolipid in chicken erythrocytes. Ceramide monohexoside was composed of more galactosylceramide than glucosylceramide. Galabiosylceramide was found in the ceramide dihexoside fraction together with lactosylceramide. Ceramide pentahexoside was a Forssman glycolipid. There were two groups of neutral sphingolipids; one had mainly C16 fatty acid and the other had C22 and C24 fatty acids. In both groups sphingosine (d18:1) was predominant as a long chain base. 2-Hydroxy-C16 fatty acid was a major component of one of the ceramide monohexosides.     

Stage-associated expression of ceramide structures in glycosphingolipids from the human trematode parasite Schistosoma mansoni

Glycosphingolipids of Schistosoma mansoni adults, cercariae and eggs comprise ceramide monohexosides (CMH) with glucose or galactose and ceramide dihexosides (CDH) with the schistosome-specific structure GalNAc(beta1-4)Glc(1-1)ceramide. Ceramide analysis revealed C18- and C20-phytosphingosines in egg CMH, C18-sphinganine as well as C18-, C19- and C20-phytosphingosines in cercarial CMH, and C18- and C20-phytosphingosines as well as C18-sphingosine and C18-sphinganine in adult CMH. For all three life cycle stages, the predominant fatty acid was C16h:0. As a characteristic feature, a range of saturated, unsaturated and hydroxylated long-chain fatty acids with 24-28 carbon atoms were additionally found in minor cercarial CMH species. The corresponding ceramides represented major constituents in cercarial CDH, while adult and egg CDH were dominated by ceramides with short fatty acid chains. The resultant ceramide patterns could be correlated with the differential expression of carbohydrate antigens on schistosomal glycolipids at various stages. A possible impact of ceramide structure on the biosynthesis of the carbohydrate moieties is discussed.     

A convenient procedure for the synthesis of ceramides

A procedure for the preparation of ceramides by direct coupling of long-chain bases and fatty acids in the presence of a mixed carbodiimide is described. This method has been used to prepare ceramides containing sphing-4-enine or sphinganine and various saturated and unsaturated fatty acids as well as saturated 2-hydroxy acids. Ceramides containing 4-hydroxy sphinganine and saturated nonhydroxy acids have also been prepared. The yields were 60-75%. The characterization of these compounds by gas-liquid chromatography-mass spectrometry as trimethylsilyl derivatives has been previously reported. Some of the ceramides are further characterized in this report by infrared spectroscopy and one compound, in addition, by elementary analysis. Use of racemic constituents for 2-hydroxy acid ceramide syntheses leads to the formation of diastereoisomers which separate by thin-layer chromatography. These were characterized by gas-liquid chromatography-mass spectrometry as the trimethylsilyl derivatives and by infrared spectroscopy. Their configurations were established by syntheses with optically active constituents.     

The human FA2H gene encodes a fatty acid 2-hydroxylase

2-Hydroxysphingolipids are a subset of sphingolipids containing 2-hydroxy fatty acids. The 2-hydroxylation occurs during de novo ceramide synthesis and is catalyzed by fatty acid 2-hydroxylase (also known as fatty acid alpha-hydroxylase). In mammals, 2-hydroxysphingolipids are present abundantly in brain because the major myelin lipids galactosylceramides and sulfatides contain 2-hydroxy fatty acids. Here we report identification and characterization of a human gene that encodes a fatty acid 2-hydroxylase. Data base searches revealed a human homologue of the yeast ceramide 2-hydroxylase gene (FAH1), which we named FA2H. The FA2H gene encodes a 372-amino acid protein with 36% identity and 46% similarity to yeast Fah1p. The amino acid sequence indicates that FA2H protein contains an N-terminal cytochrome b5 domain and four potential transmembrane domains. FA2H also contains the iron-binding histidine motif conserved among membrane-bound desaturases/hydroxylases. COS7 cells expressing human FA2H contained 3-20-fold higher levels of 2-hydroxyceramides (C16, C18, C24, and C24:1) and 2-hydroxy fatty acids compared with control cells. Microsomal fractions prepared from transfected COS7 cells showed tetracosanoic acid 2-hydroxylase activities in an NADPH- and NADPH: cytochrome P-450 reductase-dependent manner. FA2H lacking the N-terminal cytochrome b5 domain had little activity, indicating that this domain is a functional component of this enzyme. Northern blot analysis showed that the FA2H gene is highly expressed in brain and colon tissues. These results demonstrate that the human FA2H gene encodes a fatty acid 2-hydroxylase. FA2H is likely involved in the formation of myelin 2-hydroxy galactosylceramides and -sulfatides.     

Characterization of two molecular species GD3 ganglioside from bovine buttermilk

Two gangliosides, representing 85% of total lipid-bound sialic acid, have been isolated from bovine buttermilk and characterized. Both contained long-chain base, glucose, galactose and sialic acid in the molar ratio 1:1:1:2, and gave, upon sialidase treatment, a neutral glycolipid, characterized as lactosylceramide. Partial acid hydrolysis, permethylation analysis and chromium trioxide oxidation indicated their basic oligosaccharide portion to be NeuAc alpha 2----8NeuAc alpha 2----3Gal beta 1----4Glc. The difference between the two forms was exclusively in the ceramide moiety of the molecule, one containing mainly long-chain (C22-C25) fatty acids and an equimolar proportion of C16 and C18 long-chain bases, and the other mainly palmitic acid and C18 long-chain base.     

Cellular Lipid and Fatty Acid Compositions of Burkholderia pseudomallei Strains Isolated from Human and Environment in Viet Nam

Viet nam is known as an endemic area of melioidosis but its etiologic agent originated in Viet nam was not extensively studied. For the first time, we analyzed the cellular lipid and fatty acid compositions of 15 Vietnamese isolates of Burkholderia pseudomallei, 10 from humans and 5 from the environment. Cellular lipid compositions were analyzed by two-dimensional thin-layer chromatography on silica gel G plates. Cellular fatty acid methyl esters were analyzed by gas chromatography (GC) and gas chromatography/mass spectrometry (GC/MS). The major lipids in all the isolates were phosphatidylglycerol (PG), two forms of phosphatidylethanolamine (PE-1 and PE-2), and two forms of ornithine-containing lipid (OL-1 and OL-2). PE-1 contained non-hydroxy fatty acids at both sn-1 and ?2 positions, while PE-2 possessed 2-hydroxy fatty acids and non-hydroxy fatty acids in a ratio of 1: 1. Since snake venom phospholipase A₂ digestion of PE-2 liberated 2-hydroxy fatty acids, it was confirmed that these acids are at the sn-2 position of glycerol moiety. In both OL-1 and OL-2, amide-linked fatty acid was 3-hydroxy palmitic acid (3-OH-C16: 0), while ester-linked fatty acids were non-hydroxy acids in OL-1 and 2-hydroxy acids in OL-2. The total cellular fatty acid compositions of the test strains were characterized by the presence of 2-hydroxy palmitic (2-OH-C16: 0), 2-hydroxy hexadecenoic (2-OH-C16: 1), 2-hydroxy octadecenoic (2-OH-C18: 1), 2-hydroxy methylene octadecanoic (2-OH-C19CPA), 3-hydroxy myristic (3-OH-C14: 0) and 3-hydroxy palmitic (3-OH-C16: 0) acids. There were significant differences in the concentration of hexadecenoic (C16: 1), methylene hexadecanoic (C17CPA), octadecenoic (C18: 1) and methylene octadecanoic (C19CPA) acids among the Vietnamese isolates of B. pseudomallei. However, no significant difference was observed in cellular lipid and fatty acid components between strains of human and environmental origins.     

Structures and fatty acid compositions of neutral glycosphingolipids of human plasma

Major neutral glycosphingolipids were isolated from human plasma and their structures and fatty acid compositions studied. The four neutral glycosphingolipids of plasma were characterized as Glc beta(1 leads to 1)ceramide, Gal beta(1 leads to 1)- ceramide, Gal beta(1 leads to 4) Glc beta (1 leads to 1)ceramide, Gal alpha(1 leads to 4) Gal beta(1 leads to 4) Glc beta(1 leads to 1)ceramide and GalNAc beta(1 leads to 3) Gal (1 leads to 4) Gal (1 leads to 4) Glc beta(1 leads to 1)-ceramide. The glycosphingolipids contained mostly short chain fatty acids of which most prominent was C16. Erythrocyte glucosylceramide and lactosylceramide exhibited similar fatty acid compositions as their plasma counterparts. Triglycosylceramide and globoside of erythrocytes contained almost exclusively long-chain fatty acids. In lactosylceramide obtained from "p" erythrocytes, an accumulation of long-chain fatty acids was found; this accumulation was not observed, however, in lactosylceramide isolated from "p" plasma. It was concluded that plasma and erythrocyte glycosphingolipids are synthesized at separate sites where short- and long-chain fatty acids, respectively, are available. Plasma and erythrocyte glucosylceramide, and probably a fraction of lactosylceramide, exchange between plasma and erythrocyte pools. The latter conclusion is discussed in the light of the relative roles of carbohydrate and lipid moieties of the glycosphingolipids in maintaining their association with erythrocyte membranes.     

Isolation of a novel sphingoglycolipid containing glucuronic acid and 2-hydroxy fatty acid from Flavobacterium devorans ATCC 10829

A new acidic sphingoglycolipid has been isolated from a Gram-negative, glucose-non-fermentative (obligatory aerobic) bacterium, Flavobacterium devorans ATCC 10829, by thin-layer chromatography on silica gel after mild alkaline hydrolysis of the cellular lipids. Chemical degradation studies, thin-layer chromatographic behavior, IR and mass-spectrometric analysis of the original and reduced glycolipid with LiA1H4 revealed that the lipid contained glucuronic acid, long-chain bases, and fatty acids in a molar ratio of approximately 1:1:1. The major long-chain bases were identified by gas chromatography-mass spectrometry as dihydrosphingosine (d-18 :0) and longer homologues, while the N-acyl group was exclusively 2-hydroxy myristic acid. The most probable structure of this glycolipid appeared to be a ceramide glucuronic acid (N-acyl dihydrosphingosine 1-glucuronic acid).     

Identification of ceramide phosphorylethanolamine and ceramide phosphorylglycerol in the lipids of an anaerobic bacterium

Nearly half the phospholipids isolated from the anerobic bacterium Bacteroides melaninogenicus are phosphosphingolipids. The two major phosphosphingolipids have been characterized as ceramide phosphorylethanolamine and ceramide phosphorylglycerol. The long-chain bases of these phosphosphingolipids appear to have branched and normal saturated carbon chains of 17, 18, and 19 atoms; the phosphate is at the 1-position of the long-chain base. The composition of the amide-linked fatty acids of the phosphosphingolipids differs from that of the ester-linked fatty acids of the diacylphosphoglycerides in having a higher percentage of 14:0, 17:0, and 18:0 acids as well as containing nearly all the monoenoic fatty acids found in the bacterial lipids. The finding of phosphosphingolipids in bacteria is exceedingly rare and to our knowledge ceramide phosphorylglycerol has not been previously found in nature.     

The glycosphingolipid receptor for Vibrio trachuri in the red sea bream intestine is a GM4 ganglioside which contains 2-hydroxy fatty acids

Three major glycosphingolipids (tentatively designated IGL-1, 2, and 3) were isolated from the intestine of red sea bream (Pagrus major) and were subjected to a TLC-overlay assay with (35)S-labeled Vibrio trachuri which causes vibriosis of fish. The bacteria adhered to IGL-2, which was determined to be a GM4 ganglioside (NeuAcalpha2-3Galbeta1-ceramide). The fatty acid portion of IGL-2 was composed of 2-hydroxy C22:0, C24:0, and C24:1, in addition to the non-hydroxy C16:0 and C18:0, while the sphingoid base was composed exclusively of sphingenine (d18:1). Among glycosphingolipids tested, V. trachuri adhered to GM4 the most strongly followed by adherence to GM3 and GalCer, but the bacteria did not adhere to GM1a, GM2, LacCer, or GlcCer. V. trachuri was found to aggregate with the erythrocytes coated with GM4, but not with those coated with GM1a or GM2, thus indicating that specific adhesion occurs on intact cells. Interestingly, the dynamics for adhesion of V. trachuri to glycosphingolipids was defined by the structure of not only the sugar moiety but also the ceramide moiety, since the bacteria adhered to GM4 which contained 2-hydroxy fatty acids much more strongly than to that which contained non-hydroxy fatty acids.