Galactosides in glycoconjugates of Xenopus laevis testis shown by lectin histochemistry

The implication of galactosides and other glycoconjugates on spermatogenesis has been previously reported. Glycans show such a complex structure that it makes them very difficult to analyze. Lectin histochemistry is a helpful tool for the study of glycan composition. Lectin histochemistry can be combined with deglycosylation pretreatments to explore the glycan type to which carbohydrates are linked. The aim of the present work was the localization of galactose (Gal)-containing glycoconjugates in the testis of Xenopus laevis, a species widely used in cell, molecular and developmental biology. Gal specific lectins BPL, PNA, BSI-B4, MAA-I, and RCA-I, were used in combination with deglycosylation procedures. Except for BPL, all the lectins were reactive for several testicular tissues. Some of the lectins showed a different reactivity depending on the stage of spermatogenic development, suggesting that cell glycoconjugates are modified during spermatogenesis. The surface of primary spermatocytes was strongly labeled with lectins from peanut (PNA) and castor bean (RCA-I), which agrees with the presence of galactosyl-glycolipids reported in the cell membrane of mammalian spermatocytes. The acrosome was unexpectedly negative to all the lectins tested, whereas the acrosome of mammals and other amphibians has shown a high expression of glycoconjugates, including galactosides. The results obtained after deglycosylation by β-elimination or incubation with PNGase F, which respectively remove O- and N-linked oligosaccharides, allowed us to elucidate the nature of the labeled glycans. The strong expression of galactosides at the cell surface of spermatocytes and spermatids suggests the involvement of these glycans in cell adhesion mechanisms during spermatogenesis.     

Identification of mannose moieties in N- and O-linked oligosaccharides of the primordial germ cells of Xenopus embryos

The presence of mannose (Man) in the glycoconjugates of primordial germ cells (PGCs) of Xenopus embryos was elucidated by lectin histochemistry with Concanavalin A (Con A) and snowdrop (Galanthus nivalis) bulb lectin (GNA), in combination with deglycosylative pretreatments: beta-elimination, which removes O-linked oligosaccharides, and incubation with Peptide N glycosidase F (PNGase F), which removes N-linked glycan chains. In addition, histochemistry with Con A, which binds to Man and glucose (Glc), was also performed after glucose-oxidase incubation, which converts Glc into gluconic acid, and GNA was carried out after acid hydrolysis, which removes terminal sialic acid (NeuAc) moieties. PGCs were analyzed during their migration over the mesentery until the genital ridge, and after colonization of this gonad anlage. The results showed that for both lectins: (1) the PGCs and other surrounding tissue showed a similar binding pattern, and (2) the staining in the PGCs was similar in the developmental stages studied. Labeling with Con A was due to Man, and not to Glc, as shown after incubation with glucose-oxidase, and it was assumed that Man was in N-linked oligosaccharides. However, GNA labeling was mainly due to O-linked oligosaccharides, because the pretreatment of beta-elimination turned cells negative. Moreover, acid hydrolysis pretreatment gave rise to a stronger GNA-staining, suggesting that either Man was also in subterminal position to NeuAc or some Man-containing glycans were unmasked after removal of NeuAc from other oligosaccharide chains.     

Lectin binding patterns to plasmalemmal glycoconjugates of goblet cells undergoing differentiation in vitro

The plasmalemmal glycoconjugates of the HT29-18N2 (N2) cell line were characterized on cells grown as (1) undifferentiated multilayers in glucose-containing culture media and (2) monolayers of columnar cells acquiring the goblet cell phenotype in glucose-free media. Lectins were unable to bind sheets of detached N2 cells in the absence of fixation. Following fixation with aldehydes, a dramatic unmasking of lectin binding sites was seen. When fixed monolayers were stained prior to embedding, biotinylated lectins, visualized by the avidin-biotin-complexed peroxidase technique, were more efficient than collodial gold-coupled lectins. Lectin binding sites could also be detected by using collodial gold-coupled lectins to stain monolayers embedded in LR White, Lowicryl K4M, and Lowicryl HM20. The binding of 5 lectins (wheat germ, Dolichos bifluros, peanut, soybean, and Ulex europeus) was found to be independent of the stage of differentiation; “pre-differentiated” columnar cells which had prominent microvilli and no or few mucous secretory granules had identical staining patterns as well-differentiated goblet cells with large numbers of secretory granules. Ricinus communis I was the only lectin whose binding was influenced by the stage of differentiation; it intensely labeled undifferentiated multilayers of N2 cells but only weakly labeled basolateral membranes of differentiated monolayers. Canavalia ensiformas (ConA) caused a moderate and even labeling of both apical and basolateral membranes of fixed monolayers stained prior to embedding, but post-embedding labeling revealed heavy labeling along the lateral margins of all columnar cells and weak to moderate binding along the apical and basal cell surface.     

Role of the golgi apparatus in cellular pathology

The Golgi apparatus response to pathological disorders is predominantly as an intermediary component of membrane biogenesis where it is involved in processing, sorting and secretion of materials via secretory granules, and in the formation of lysosomes. A common initial response of the Golgi apparatus to any stress is an alteration or cessation of secretory activity. In the transformed cell, the Golgi apparatus is altered both morphologically and biochemically, suggesting a shift from a secretory to a membrane-generating mode of functioning. However, since fewer or less well-developed Golgi apparatus are frequently found in transformed cells, analytical methods of membrane isolation developed for normal tissues may not always yield equivalent results when applied to tumors. Cell surface alterations characteristic of malignant cells may result from modifications occurring at the level of the Golgi apparatus. Some lysosomal dysfunctions may result from underglycosylation of acid hydrolases by the Golgi apparatus. The use of cell-free systems between endoplasmic reticulum and Golgi apparatus or within Golgi apparatus cisterane is providing a new approach to the elucidation of the role of the Golgi apparatus in normal as well as pathological states.     

Mass spectrometric glycan rearrangements

Mass spectrometric rearrangement reactions have been reported for a large variety of compounds such as peptides, lipids, and carbohydrates. In the case of carbohydrates this phenomenon has been described as internal residue loss. Resulting fragment ions may be misinterpreted as fragments arising from conventional glycosidic bond cleavages, which may result in incorrect structural assignment. Therefore, awareness of the occurrence of glycan rearrangements is important for avoiding misinterpretation of tandem mass spectra. In this review mass spectrometric rearrangements of both derivatized and underivatized (native) oligosaccharide structures are discussed. Similar phenomena have been reported for glycopeptides, labeled glycan structures and other biomolecules containing a carbohydrate part. Rearrangements in oligosaccharides and glycoconjugates have been observed with different types of mass spectrometers. Most of the observed carbohydrate rearrangement reactions appear to be linked to the presence of a proton. Hence, tandem mass spectrometric analysis of alkali adducts or deprotonated ions often prevents rearrangement reactions, while they may happen with high efficacy with protonated glycoconjugates.     

Effects of brefeldin-A on Golgi morphology in human cultured fibroblasts observed in three-dimensional stereo scanning electron microscopy

Brefeldin A (BFA) has been reported to cause disassembly of the Golgi. We have used three-dimensional (3-D) high-resolution scanning electron microscopy (HRSEM) to investigate these effects in human skin fibroblast cells. The spontaneous reassembly during prolonged exposure to BFA and some effects of forskolin were observed. A BFA concentration of 5μg/ml caused Golgi complexes to become vesicular, resulting in a progressive decrease in the size of the Golgi. Morphologic changes were visible within 2 min of BFA incubation, and by 30 min no identifiable Golgi could be found. Spontaneous reassembly of the Golgi apparatus upon the removal of the BFA or with continued long-term exposure with BFA could not be confirmed. Preliminary experiments with forskolin were not effective in reversing or inhibiting the effects of BFA in human fibroblast cells grown in culture. This inability for spontaneous reassembly and nonreversal by forskolin may reflect a differential effect of BFA in various cell types. HRSEM has proven to be useful for observing 3-D morphologic effects of BFA in Golgi.     

Comparative histochemical analysis of glycoconjugates in the nasal vestibule of camel and sheep

While Corriedale sheep survive in a wide range of climates, which prevents them to specialize for one climatic condition only, dromedary camels strictly adapted to desert areas. This demands more adaptive mechanisms to hot, dry conditions in camels than in sheep. Being the entrance of the nasal cavity, nasal vestibule is subjected to various environmental stressors. A protective way is the lining epithelium which is cornified in camel, but not in sheep. Mucus nasal secretions also play a key role in the protection of underlyings. Additionally, arterio‐venous anastomosis is present in the lamina propria of the nasal vestibule of camel. In the present paper, sugar residues in the nasal vestibule of camel were analyzed and compared with those of sheep using 14 types of lectins to explore the distribution of glycoconjugates that may help the function of camel nasal vestibule in desert environment. In camel, none of the lectins could label the basal cells of the vestibular epithelium, although the basal cells reacted with six lectins in sheep. In camel, LEL and RCA‐120 markedly labeled the luminal surface. WGA, DBA, SBA, and VVA produced marked intensities on the luminal surface in sheep. The mucous glands reacted with six lectins: WGA, s‐WGA, VVA, PNA, PHA‐E, and PHA‐L in camel, while all lectins used except s‐WGA and PHA‐E reacted in the sheep. In summary, great differences are observed in the glycoconjugate expression between camel and sheep. This suggests that these glycoconjugate are related to camel's tolerance for environmental stressors.     

Comparisons of golgi structure and dynamics in plant and animal cells

The Golgi apparatus of both higher plant and animal cells sorts and packages macromolecules which are in transit to and from the cell surface and to the lysosome (vacuole). It is also the site of oligosaccharide and polysaccharide synthesis and modification. The underlying similarity of function of plant and animal Golgi is reflected in similar morphological features, such as cisternal stacking. There are, however, several fundamental differences between the Golgi of plant and animal cells, reflecting, in large part, the fact that the extracellular matrices and lysosomal systems differ between these kingdoms. These include (1) the form and replication of the Golgi during cell division; (2) the disposition of the Golgi in the interphase cell; (3) the nature of “anchoring” the Golgi in the cytoplasm; (4) the genesis, extent, and nature of membranes at the trans side of the stack; (5) targeting signals to the lysosome (vacuole); and (6) physiological regulation of secretion events (constitutive vs. regulated secretion). The degree of participation of the Golgi in endocytosis and membrane recycling is becoming clear for animal cells, but has yet to be explored in detail for plant cells.     

Brefeldin A effects in plant and fungal cells: something new about vesicle trafficking?

Whilst the function and organization of the secretory machinery in eukaryotic cells exhibit basic similarities, the compartmentation of the endomembrane system can show significant differences between the fungal, plant and animal kingdoms. The use of the antibiotic brefeldin A (BFA) as an inhibitor of secretion in both animal and yeast cells has resulted in a remarkable advance in our understanding of the modes of action of vesicle shuttles between the endoplasmic reticulum and Golgi apparatus and within the Golgi apparatus itself. It is now apparent that application of the drug to filamentous fungi and plants will also help unravel the workings of the secretory system in these organisms. In this paper we review recent progress in our laboratories on elucidating the effects of BFA on the morphology of the Golgi apparatus and compare these with recently published data on fungal and plant cells. Variation in the response to BFA are reported, which may not all be attributed to differences in drug concentration and time of treatment. These may reflect differences in cellular sensitivity or multiple sites of action of the drug, and the existence of a specific molecular target for BFA is questioned.     

Mineralization patterns in elasmobranch fish

This article reviews current findings on the organic matrix and the mineralization patterns in elasmobranchs, including an analysis of the role of the dental epithelial cells and the odontoblasts during odontogenesis. Our electron micrographs demonstrated that tubular vesicles limited by a unit membrane occupied the bulk of the elasmobranch enameloid matrix during the stage of enameloid matrix formation. It is likely that the tubular vesicles originated from the odontoblast processes. Two types of electron-dense fibrils, with cross-striations at intervals of approximately either 17 nm or 55 nm, respectively, were detected in the enameloid matrix. These data suggest that odontoblasts were strongly involved in enameloid matrix formation and in initial enameloid mineralization. Two types of odontoblasts, dark and light cells, were recognized during the stage of dentinogenesis. The light cells contained numerous mitochondria, intermediate filaments, and microtubules that extended their processes into the dentin. The dark cells possessed a well-developed Golgi apparatus and many cisternae in the rough endoplasmic reticulum, which suggests that the dark cells are involved in the formation of dentin. The inner dental epithelial (IDE) cells exhibited a well-developed Golgi apparatus, many mitochondria, cisternae of smooth endoplasmic reticulum, vesicles, vacuoles, and granules during the mineralization and maturation stages. During the stages of mineralization and early maturation, ACPase-positive granules were visible in the IDE cells and ALPase and Ca-ATPase activities were found at the lateral and proximal cell membrane of the IDE cells, suggesting that the IDE cells are involved in the removal of enameloid organic matrix and in the process of mineralization during later stages of enameloid formation. Our data indicate that elasmobranch enameloid is distinct from teleost enameloid, based on its organic content, on the mechanisms of its mineralization, and on the role of IDE cells concerning enameloid formation.     

Plant Golgi ultrastructure

The plant Golgi apparatus (sensu lato: Golgi stack + Trans Golgi Network, TGN) is a highly polar and mobile key organelle lying at the junction of the secretory and endocytic pathways. Unlike its counterpart in animal cells it does not disassemble during mitosis. It modifies glycoproteins sent to it from the endoplasmic reticulum (ER), it recycles ER resident proteins, it sorts proteins destined for the vacuole from secretory proteins, it receives proteins internalised from the plasma membrane and either recycles them to the plasma membrane or retargets them to the vacuole for degradation. In functional terms the Golgi apparatus can be likened to a car factory, with incoming (COPII traffic) and returning (COPI traffic) railway lines at the entry gate, and a distribution centre (the TGN) at the exit gate of the assembly hall. In the assembly hall we have a conveyor belt system where the incoming car parts are initially assembled (in the cis-area) then gradually modified into different models (processing of secretory cargo) as the cars pass along the production line (cisternal maturation). After being released the trans-area, the cars (secretory cargos) are moved out of the assembly hall and passed on to the distribution centre (TGN), where the various models are placed onto different trains (cargo sorting into carrier vesicles) for transport to the car dealers. Cars with motor problems are returned to the factory for repairs (endocytosis to the TGN). This simple analogy also incorporates features of quality control at the COPII entry gate with defective parts being returned to the manufacturing center (the ER) via the COPI trains (vesicles). In recent years, numerous studies have contributed to our knowledge on Golgi function and structure in both animals, yeast and plants. This review, rather than giving a balanced account of the structure as well as of the function of the Golgi apparatus has purposely a marked slant towards plant Golgi ultrastructure integrating findings from the mammalian/animal field.     

Perspectives on golgi apparatus form and function

In 1898, Camillio Golgi reported a new cellular constituent with the form of an extensive intracellular network (the apparato reticolare interno), which now bears his name. However, the history of Golgi's apparatus is replete with controversy regarding its reality, what components of the cell should be included under its aegis, and what terminology should be used when referring to it. Electron microscopy has resolved many of these controversies and it is appropriate that this volume emphasize that aspect of Golgi apparatus discovery. The principal structural component of the Golgi apparatus is the stack of cisternae, or dictyosome. As determined both biochemically and at the level of electron microscopy, the dictyosome is a highly ordered and polarized structure. The maintenance of order within the stack is thought to result from either intercisternal bonding constituents, or filamentous structures (or both) that bridge the space between adjacent cisternae. Mechanisms proposed for movement of membrane and product into and out of the dictyosome (i.e., the Golgi apparatus stack) include a serial mode which functions exclusively by the formation, displacement, and loss of cisternae from the stack, and a parallel mode which functions exclusively by the movement of membrane, product, or precursor molecules directly into the peripheral edges of the cisternae. In the parallel mode, all cisternae can be accessed either singly or simultaneously, at least in theory, at any position within the stack. It is probable that both the serial and the parallel modes function concomitantly and need not be mutually exclusive. Finally, the peripheral tubules of the cisternae represent a major membranous constituent of the cell with potentially unique functions. These tubules interconnect cisternae of adjacent stacks and may represent the major site of receptors for the shuttle (i.e., parallel) type of transfer among cisternae. Peripheral tubules as extensions of the cisternal lumina into the cytoplasm presumably have other functions, but these, like the tubules themselves, have only rarely been accommodated into functional models of Golgi apparatus dynamics in secretion or membrane flow.     

Localization of glycosylation sites in the golgi apparatus using immunolabeling and cytochemistry

This review summarizes data on the distribution of certain glycosylation steps in the Golgi apparatus as revealed by immunolabeling and lectin techniques. The methodical basis for such investigations was provided by the introduction of the colloidal gold marker system for immunolabeling and the development of new means of tissue processing such as the low-temperature embedding technique using Lowicryl K4M. The application of these techniques together with highly specific antibodies has provided much of the basis for our current understanding of the Golgi apparatus in functional terms. Thus, in many cell types, three Golgi apparatus compartments can be distinguished, whereas in others no such functional subdivision is evident. Investigations on sialyltransferase distribution have also provided direct evidence that GERL is structurally and functionally part of the Golgi apparatus.     

Postembedment staining of complex carbohydrates: Influence of fixation and embedding procedures

In recent years technological advancements have led to improvements in ultrastructural cytochemical methods for localizing and characterizing complex carbohydrates. In particular the introduction of lectins with specific affinities for various sugars and sugar sequences as histochemical probes has increased knowledge concerning the cellular and subcellular distribution of glycoconjugates. Development of nonepoxy-based embedding materials has provided increased sensitivity compared to the earlier less specific methods and the current lectin methods for localizing sugar moieties. Postembedment staining based on the reactivity of functional groups present in sugars, such as hydroxyl groups, vicinal diol groups, carboxyl groups, and sulfate esters, requires specific conditions for tissue fixation and embedding. The same requirements pertain to staining based on lectin binding. The influence of fixation and embedment using older and newly developed embedding mixtures on the ultrastructural demonstration of complex carbohydrates is considered in this discussion. Fixation with osmium tetroxide and embedment in epoxy resins provides the least sensitive combination for the detection of the reactive groups of complex carbohydrates. The best ultrastructural demonstration of glycoconjugates is achieved when nonosmicated tissues are embedded in nonepoxy resins.     

Traffic through the golgi apparatus as studied by radioautography

The ability to radiolabel biological molecules, in conjunction with radioautographic or cell fractionation techniques, has brought about a revolution in our knowledge of dynamic cellular processes. This has been particularly true since the 1940's, when isotopes such as ³⁵S and ¹⁴C became available, since these isotopes could be incorporated into a great variety of biologically important compounds. The first dynamic evidence for Golgi apparatus involvement in biosynthesis came from light microscope radioautographic studies by Jennings and Florey in the 1950's, in which label was localized to the supranuclear Golgi region of goblet cells soon after injection of ³⁵S-sulfate. When the low energy isotope tritium became available, and when radioautography could be extended to the electron microscope level, a great improvement in spatial resolution was achieved. Studies using ³H-amino acids revealed that proteins were synthesized in the rough endoplasmic reticulum, migrated to the Golgi apparatus, and thence to secretion granules, lysosomes, or the plasma membrane. The work of Neutra and Leblond in the 1960's using ³H-glucose provided dramatic evidence that the Golgi apparatus was involved in glycosylation. Work with ³H-mannose (a core sugar in N-linked side chains), showed that this sugar was incorporated into glycoproteins in the rough endoplasmic reticulum, providing the first radioautographic evidence that glycosylation of proteins did not occur solely in the Golgi apparatus. Studies with the tritiated precursors of fucose, galactose, and sialic acid, on the other hand, showed that these terminal sugars are mainly added in the Golgi apparatus. With its limited spatial resolution, radioautography cannot discriminate between label in adjacent Golgi saccules. Nonetheless, in some cell types, radioautographic evidence (along with cytochemical and cell fractionation data) has indicated that the Golgi is subcompartmentalized in terms of glycosylation, with galactose and sialic acid being added to glycoproteins only within the trans-Golgi compartment. In the last ten years, radioautographic tracing of radioiodinated plasma membrane molecules has indicated a substantial recycling of such molecules to the Golgi apparatus.     

Analysis of carbohydrates and glycoconjugates by matrix-assisted laser desorption/ionization mass spectrometry: An update for 2003-2004

This review is the third update of the original review, published in 1999, on the application of matrix-assisted laser desorption/ionization (MALDI) mass spectrometry to the analysis of carbohydrates and glycoconjugates and brings the topic to the end of 2004. Both fundamental studies and applications are covered. The main topics include methodological developments, matrices, fragmentation of carbohydrates and applications to large polymeric carbohydrates from plants, glycans from glycoproteins and those from various glycolipids. Other topics include the use of MALDI MS to study enzymes related to carbohydrate biosynthesis and degradation, its use in industrial processes, particularly biopharmaceuticals and its use to monitor products of chemical synthesis where glycodendrimers and carbohydrate-protein complexes are highlighted.     

Analysis of carbohydrates and glycoconjugates by matrix‐assisted laser desorption/ionization mass spectrometry: An update for the period 2005–2006

This review is the fourth update of the original review, published in 1999, on the application of MALDI mass spectrometry to the analysis of carbohydrates and glycoconjugates and brings coverage of the literature to the end of 2006. The review covers fundamental studies, fragmentation of carbohydrate ions, method developments, and applications of the technique to the analysis of different types of carbohydrate. Specific compound classes that are covered include carbohydrate polymers from plants, N‐ and O‐linked glycans from glycoproteins, glycated proteins, glycolipids from bacteria, glycosides, and various other natural products. There is a short section on the use of MALDI‐TOF mass spectrometry for the study of enzymes involved in glycan processing, a section on industrial processes, particularly the development of biopharmaceuticals and a section on the use of MALDI–MS to monitor products of chemical synthesis of carbohydrates. Large carbohydrate–protein complexes and glycodendrimers are highlighted in this final section. © 2010 Wiley Periodicals, Inc., Mass Spec Rev 30:1–100, 2011     

Backscattered electron image of osmium‐impregnated/macerated tissues as a novel technique for identifying the cis‐face of the Golgi apparatus by high‐resolution scanning electron microscopy

The osmium maceration method with scanning electron microscopy (SEM) enabled to demonstrate directly the three‐dimensional (3D) structure of membranous cell organelles. However, the polarity of the Golgi apparatus (that is, the cis–trans axis) can hardly be determined by SEM alone, because there is no appropriate immunocytochemical method for specific labelling of its cis‐ or trans‐faces. In the present study, we used the osmium impregnation method, which forms deposits of reduced osmium exclusively in the cis‐Golgi elements, for preparation of specimens for SEM. The newly developed procedure combining osmium impregnation with subsequent osmium maceration specifically visualised the cis‐elements of the Golgi apparatus, with osmium deposits that were clearly detected by backscattered electron‐mode SEM. Prolonged osmication by osmium impregnation (2% OsO₄ solution at 40°C for 40 h) and osmium maceration (0.1% OsO₄ solution at 20°C for 24 h) did not significantly impair the 3D ultrastructure of the membranous cell organelles, including the Golgi apparatus. This novel preparation method enabled us to determine the polarity of the Golgi apparatus with enough information about the surrounding 3D ultrastructure by SEM, and will contribute to our understanding of the global organisation of the entire Golgi apparatus in various differentiated cells.     

Trans-Golgi reticulum

The trans-Golgi apparatus reticulum is that portion of the Golgi apparatus located in the trans-most aspect of the stack exhibiting certain characteristic morphological and functional characteristics. The membranes of the trans-Golgi reticulum are reticular in form, thickened with plasma membrane-like characteristics and with a considerable portion of their surface covered by clathrin coats. The enzymes thiamine pyrophosphatase and sialyl- and galactosyl transferases are functional markers. Correlative studies show the trans-Golgi apparatus reticulum to be involved in glycoprotein, enzyme and receptor processing and sorting along multiple pathways. Sorting and transfer of constituents to lysosomes, to secretory granules, or to the plasma membrane emerge as dominant functions.     

Analysis of carbohydrates and glycoconjugates by matrix-assisted laser desorption/ionization mass spectrometry: an update for 2007-2008

This review is the fifth update of the original review, published in 1999, on the application of MALDI mass spectrometry to the analysis of carbohydrates and glycoconjugates and brings coverage of the literature to the end of 2008. The first section of the review covers fundamental studies, fragmentation of carbohydrate ions, use of derivatives and new software developments for analysis of carbohydrate spectra. Among newer areas of method development are glycan arrays, MALDI imaging and the use of ion mobility spectrometry. The second section of the review discusses applications of MALDI MS to the analysis of different types of carbohydrate. Specific compound classes that are covered include carbohydrate polymers from plants, N- and O-linked glycans from glycoproteins, biopharmaceuticals, glycated proteins, glycolipids, glycosides and various other natural products. There is a short section on the use of MALDI mass spectrometry for the study of enzymes involved in glycan processing and a section on the use of MALDI MS to monitor products of the chemical synthesis of carbohydrates with emphasis on carbohydrate-protein complexes and glycodendrimers. Corresponding analyses by electrospray ionization now appear to outnumber those performed by MALDI and the amount of literature makes a comprehensive review on this technique impractical. However, most of the work relating to sample preparation and glycan synthesis is equally relevant to electrospray and, consequently, those proposing analyses by electrospray should also find material in this review of interest.