Ganglioside patterns and cholera toxin--peroxidase labeling of aggregating cells from the chick optic tectum

Age-related changes in GM1, GD1a, GT1b components of gangliosides in Wistar albino rats

In this study, age-related changes of GM1, GD1a, GT1b fractions of gangliosides were investigated in whole brain of male Wistar albino rats. Insignificant increases were detected in GM1 values from the third to the 24th month, whereas GD1a and GT1b concentrations of ganglioside in 24-month-old rats decreased significantly as compared to 6-month-old rats. Although there were no significant differences in the GD1a/GT1b ratio of any groups, GM1/GD1a and GM1/GT1b ratios were significantly increased as compared to 6-month-old rats. The increase in the ratios of gangliosides are not due to an increase of GM1 fractions; they result from a decrease of GD1a and GT1b fractions of gangliosides. In conclusion, the concentration of ganglioside decreased with ageing.

Neuronal cells mature faster on polyethyleneimine coated plates than on polylysine coated plates

Cell morphology, protein/DNA ratio, ganglioside analysis, taurine uptake, and the activity of neurone specific enolase showed that neuronal cells mature faster when grown on polyethyleneimine coated plates compared to cells grown on polylysine coated plates. Our results also show higher protein/DNA ratio and total and neuron specific enolase activities in cells grown in serum supplemented medium, when compared to their counterparts grown in synthetic medium. Moreover, our results show that only some specific markers can be used to determine the early and late events of cell maturation, whereas other markers continuously vary with time.

Changes of mouse brain gangliosides during aging from young adult until senescence

The brain gangliosides from young adult to senescent mice (BDF1 and C57BL/6) were studied. The total ganglioside concentrations of the whole brains were almost constant from young adulthood until the beginning of senescence, but decreased constant from young adulthood until the beginning of senescence, but decreased during senescence to about 80% of the constant level observed at the period before the beginning of senescence. In spite of the constancy of the ganglioside concentrations at the period before the beginning of senescence, the composition gradually changed, with an increase of GM1 and decreases of GD1b, GT1b and GQ1b. During the senescence, all of the gangliosides decreased in their concentrations, but GD1a, GT1b and GQ1b decreased to a markedly greater extent (GT1b greater than GD1a greater than GQ1b). The regional gangliosides in olfactory bulb, cerebrum cortex, cerebrum white matter, hippocampus, hypothalamus, cerebellum and medulla oblongata were compared between 3- and 30-month-old mice of both strains. Significant changes in ganglioside concentrations were observed in both strains in the cerebrum and the hippocampus. In the cerebrum white matter, cerebellum and medulla oblongata, GM1 and GM4 contents significantly increased in the senescent mice.

Ganglioside composition of normal and mutant mouse embryos

The enrichment of gangliosides in neuronal membranes suggests that they play an important role in CNS development. We recently found a marked tetrasialoganglioside deficiency in twl/twl mutant mouse embryos at embryonic day (E)-11. The recessive twl/twl mutants die at embryonic ages E-9 to E-18 from failed neural differentiation in the ventral portion of the neural tube. In the present study, we examined the composition and distribution of gangliosides in twl/twl mutant mouse embryos at E-12. The total ganglioside sialic acid concentration was significantly lower in the mutants than in normal (+/-) embryos. The mutants also expressed significant deficiencies of gangliosides in the "b" metabolic pathway (GD3, GD1b, GT1b, and GQ1b) and elevations in levels of gangliosides in the "a" metabolic pathway (GM3, GM2, GM1, and GD1a). These findings suggest that the mutants have a partial deficiency in the activity of a specific sialyltransferase in the b pathway. Regional ganglioside distribution was also studied in E-12 normal mouse embryos. The ganglioside composition in heads and bodies was similar to each other and to whole embryos. Total ganglioside concentration and the distribution of b pathway gangliosides were significantly higher in neural tube regions than in nonneural tube regions. These findings suggest that b pathway gangliosides accumulate in differentiating neural cells and that the deficiency of these gangliosides in the twl/twl mutants is closely associated with failed neural differentiation.

Biosynthesis and expression of gangliosides during differentiation of chick embryo retina cells in vitro

Cells from neural retina from 7-day chick embryos were cultured on polylysine-coated dishes up to 7 days. The small, round-shaped cells at seeding differentiated progressively, and after 4 days in vitro the majority had enlarged bodies and abundant processes. The content of protein and DNA was essentially unchanged during the entire period of culture. The incorporation of radioactivity from [3H]glucosamine into gangliosides declined slightly, reaching about 65% of the initial values at the end of the culture period. The proliferating activity measured by the incorporation of [3H]thymidine into DNA decreased to 10% or less of the initial value after 3 days in vitro. Almost at the same chronological times as in ovo, the synthesis of GD3 and of a ganglioside partially identified as GT3 decreased from 70 and 19% of the total incorporation into gangliosides in the first 20 h of culture to about 7 and 5%, respectively, after 3 days in vitro. Conversely, the synthesis of GD1a increased from about 6% at the beginning to about 70% at the end of the culture times. Immunocytochemical analyses of the expression of gangliotetraosyl gangliosides in cultured cells showed that these gangliosides appeared in the bodies and processes of cells having neuronal morphology; very little immunostaining of the scarce flattened cells, probably Müller cells, was found. The results indicate that the changes in ganglioside metabolism, which lead to decreased synthesis of gangliosides lacking the galactosyl-N-acetyl-galactosaminyl disaccharide end and to increased synthesis of gangliotetraosyl gangliosides, occur in cells that in culture differentiate into neurons.

Neuritogenic and metabolic effects of individual gangliosides and their interaction with nerve growth factor in cultures of neuroblastoma and pheochromocytoma

The 4 major ganglioside species, GM1, GD1a, GD1b and GT1b (200 micrograms/ml), were tested individually for the ability to stimulate neuronal trophic responses. The growth parameters measured were: morphologic changes, quantitated by computer-assisted morphometry of neurite length and number per soma, and metabolic changes, indicated by alterations in ornithine decarboxylase activity (ODC). In addition, the interaction of each ganglioside with nerve growth factor (NGF) was investigated with an NGF-responsive pheochromocytoma PC12 cell line and NGF-insensitive neuroblastoma Neuro-2a cultures. PC12 cells responded to gangliosides only in the presence of NGF (20 micrograms/ml): GM1 produced the greatest morphologic response, but did not alter metabolic levels; GT1b increased both parameters. The presence (5 micrograms/ml) or absence of NGF did not have an effect on the ganglioside-mediated morphologic responses of Neuro-2a cells to each species: GD1b elicited the greatest increase in neurite length, while GD1a and GT1b stimulated both length and number. In contrast, while GT1b alone was able to elevate ODC activity independently of NGF, the simultaneous exposure of Neuro-2a cultures to NGF and GM1 or GD1a resulted in a stimulation of cellular metabolism. These results indicate that each ganglioside species has a specific target action in the stimulation of different trophic responses and that performance in one category is not a predictor of the result in another. In addition, it is possible to confer a sensitivity to NGF by simultaneous treatment with specific gangliosides. This indicates that membrane gangliosides may modulate the actions of neurotrophic factors.

Ganglioside GD3: structure, cellular distribution, and possible function

Insight on the function of gangliosides can emerge from knowledge of their cellular distribution. In this paper we review the structure of ganglioside GD3 and recent information on its cellular distribution. GD3 appears to be enriched in a variety of neural cell types including: reactive glia, gliomas, undifferentiated neurons, Muller glia, and oligodendroglia. Because each of these cell types share an enhanced permeability to ions and metabolites or possess properties associated with enhanced permeability, we suggest that GD3 is associated with enhanced membrane permeability. A possible function for GD3 in membrane permeability has implications for other cellular events such as metabolism, growth and interactions.

Cellular distribution of gangliosides in the developing mouse cerebellum: analysis using the staggerer mutant

The distribution of cerebellar gangliosides was studied in staggerer (sg/sg) mutant mice, where the majority of granule cells die after completing their migration across the molecular layer. In addition, the external granule cell layer in sg/sg mice persists longer than in normal mice. Moreover, in the sg/sg cerebellum, Purkinje cells are significantly reduced in number, and almost none have tertiary branchlet spines. The loss of Purkinje cells and granule cells in sg/sg mice is accompanied by an early-onset reactive gliosis that continues through adulthood. By correlating changes in ganglioside composition with the well-documented histological events of cerebellar development in normal and sg/sg mice, we obtained strong evidence for a nonrandom cellular distribution of gangliosides. The sharpest reduction in the GD1a content of sg/sg cerebellum occurred after 15 days of age, coincident with granule cell loss. GT1a, on the other hand, was significantly reduced from 15 through 150 days in the sg/sg mice. GD3 is a major ganglioside of the undifferentiated granule cell, but it becomes rapidly displaced by the more complex gangliosides with the onset of granule cell maturation. In the sg/sg mice, GD3 persisted at abnormally high levels from 15 to 28 days and then accumulated through adulthood. These findings, and those from other cerebellar mouse mutants, suggest that GD1a is enriched in granule cells and that GT1a is enriched in Purkinje cells. Our findings also suggest that GT1a is more concentrated in branchlet spines than in other regions of the Purkinje cell membrane. GT1b appears to be enriched in both granule cells and Purkinje cells, whereas GM1 appears to be enriched in myelin. Furthermore, the apparent persistence of the embryonic ganglioside GD3 in sg/sg mice results from an early-onset reactive gliosis, together with a partial retardation in granule cell maturation. The accumulation of GD3 beyond 28 days reflects the continued accretion of GD3 in reactive glia.

Cellular localization of gangliosides in the mouse cerebellum: analysis using neurological mutants

We have used genetic dissection to study the cellular localization of gangliosides in the mouse cerebellum. This method employs a series of mouse mutations that destroy specific populations of cerebellar neurons at precise stages of development. By correlating the well documented histological changes occurring in these mutants with changes in ganglioside composition, we have obtained strong evidence for a non-random cellular distribution of gangliosides. Most notably, GD1a is more enriched in granule cells that in Purkinje cells, whereas the opposite is true for GT1a. GD3, on the other hand, is heavily enriched in reactive glia and may serve as a useful biochemical marker for the presence of reactive glia in neurological disease. The continued study of gangliosides in the various mouse mutants will help elucidate their cellular localization in the CNS.

Phylogeny and ontogeny of vertebrate brain gangliosides

Gangliosides evolved relatively recently in the history of life, thus their contribution to fundamental cellular processes must be ancillary to or superimposed on preexisting mechanisms. Brain ganglioside patterns vary along taxonomic lines in a fairly conservative fashion, indicating that general ecophysiological factors have probably provided the major selective constraints. During brain development in birds and mammals, gangliosides pass through a transient stage of pattern complexity that may reflect their reptilian ancestry. While this ganglioside heterogeneity could provide positional information within the developing tissue, it might merely reflect a necessary but incidental transition to the handful of major gangliosides essential to mature brain function.

Differential expression of gangliosides on the surfaces of myelinated nerve fibers

The binding of cholera and tetanus toxins to receptors on the surfaces of teased nerve fibers was used to localize GM1 and G1b-series gangliosides, respectively, by immunocytochemical methods. Native fibers and fibers treated with various hydrolytic enzymes to degrade specific surface components were studied. With native fibers, both toxins bound abundantly to nodes of Ranvier and poorly to the most external, internodal Schwann cell surfaces. Treatment of the fibers with proteases, hyaluronidase, and chondroitin ABC lyase neither eliminated receptors at the nodes nor unmasked receptors over the internodes. The axolemma underlying the paranodal or internodal myelin, exposed by extensive treatment with protease, bound both toxins in large amounts. Neuraminidase action induced cholera toxin receptors on the Schwann cell surface; these receptors were insensitive to protease. The results indicate that GM1 and G1b-series gangliosides are predominantly localized to axonal and glial structures of the node of Ranvier and to paranodal/internodal Axolemma, and that polysialogangliosides not of the G1b-series are present on the internodal Schwann cell surface.

Ganglioside localization on myelinated nerve fibres by cholera toxin binding

GM1 ganglioside has been localized on the surfaces of myelinated, peripheral nerve fibres by using immunofluorescence to detect cholera toxin receptors. Unfixed, mouse sciatic nerves were teased into individual, intact fibres in order to expose their extracellular surfaces. Cholera toxin binding sites were abundant at all nodes of Ranvier; they were scarce on the internodal fibre surfaces. The nodal receptors were resistant to various degradative enzymes, including trypsin and proteinase K. Proteases did not unmask receptors on the internodal surfaces. Exogenous GM1 successfully competed for the toxin binding sites on the fibres. From this evidence and the specificity of cholera toxin binding, we conclude that GM1 ganglioside is abundantly present on the membrane surfaces of peripheral nodes of Ranvier and is not present on the internodal Schwann cell surfaces in an appreciable amount. The patterns of fluorescence within the node suggest that the axon and Schwann cell structures are sites where GM1 is localized. Treatment of the teased fibres with Vibrio cholerae neuraminidase, which is known to reduce polysialogangliosides to the monosialoganglioside GM1, induced cholera toxin binding on the internodal Schwann cell surfaces. The induced receptors, as well as their precursors, were resistant to trypsin and proteinase K. We conclude that the internodal Schwann cell surface is rich in an unidentified polysialoganglioside(s) that can be converted to GM1 by neuraminidase.

Cellular localization of gangliosides in the developing mouse cerebellum: analysis using the weaver mutant

The distribution of gangliosides was studied in the weaver (wv/wv) mutant mouse, where the vast majority of postmitotic granule cell neurons die prior to their differentiation. The wv mutation also shows a dosage effect, as granule cell migration is slowed or retarded in the +/wv heterozygotes. By correlating changes in ganglioside composition with the well-documented histological events that occur during cerebellar development in the normal (+/+), heterozygous (+/wv), and weaver (wv/wv) mutant mice, information was obtained on the cellular localization and function of gangliosides. Ganglioside GM1 may be enriched in granule cell growth cones and play an important role in neurite outgrowth. A striking accumulation of GM1, which may result from altered metabolism, occurred in the adult wv/wv mice. GD3 was heavily concentrated in undifferentiated granule cells, but was rapidly displaced by the more complex gangliosides during differentiation. GD1a became enriched in granule cells during formation of synaptic and dendritic membranes, whereas GT1a appeared enriched in Purkinje cell synaptic spines. A possible fucose-containing ganglioside was quantitated only in the wv/wv mice. Ganglioside GT1b became enriched in granule cells during synaptogenesis, whereas GQ1b became enriched in these cells after synaptogenesis. The concentrations of GT1b and especially GQ1b increased continuously with age. Our results provide further evidence for a differential cellular enrichment of gangliosides in the mouse cerebellum and also suggest that certain gangliosides may be differentially distributed within the membranes of these cells at various stages of development.

Synaptic membrane domains in photoreceptors of chick retina: a thin-section and a freeze-fracture study

In this freeze-fracture study of synaptic terminals of chick photoreceptors, three regions of synaptic terminal plasmalemma can be distinguished on the basis of intramembrane characteristics. The first region is the synaptic vesicle fusion region in which rows of P-face depressions and E-face mounds are observed. In the absence of exocytotic figures this zone is relatively free of P-face particles and E-face pits. Adjacent to this, a second region is seen, rich in P-face particles and complementary E-face pits. This second region waxes and wanes in size during dark and light stimulation (Cooper and McLaughlin, 1982) and may correspond to similar expansions and contractions of synaptic plasmalemma induced by less physiological modes of stimulation, as observed in other synaptic terminals (Ceccarelli et al., 1979b; Model et al., 1975; Boyne and McLeod, 1979). During the waxing period, P-face particles and E-face pits are present in this membrane, and its expansion gives rise to diverticula of the synaptic terminal. During the waning period when the diverticula begin to disappear, aggregates of P-face particles and complementary patches of E-face pits are seen in the diverticular membrane. The third region, the nonsynaptic plasmalemma enclosing the terminal, contains a high density of P-face particles but does not contain E-face pits. Serial sections of vacuoles within the cytoplasm demonstrate that some vacuoles retain connections with this nonsynaptic plasmalemma. Vacuoles that are connected in this way are depleted of intramembrane particles. Such regions appear to represent separate domains within the photoreceptor terminal and are discussed in the context of membrane addition and retrieval.

Ganglioside changes in the chicken optic lobes as biochemical indicators of brain development and maturation

The development profiles of 16 different gangliosides of the optic lobes of the chicken were followed from the sixth day of incubation to the tenth posthatching week and correlated to known morphological development. Several, previously undetected novel fractions occurred between the sixth and the tenth embryonic days. According to their migration rates on TLC-plates 4 of them may be GT3, GT2, GT1c, GQ1c. Three even more slowly migrating fractions represent penta-, hexa-, and septa-sialogangliosides. At the sixth day of incubation, characterized by maximal proliferation of neuroepithelial cells, the optic lobes contained predominantly GD3. Up to the eleventh day of incubation, parallel to decreased mitotic activity, maximal cell migration and neuron differentiation, GD3, GD2, and GT3 decreased in favor of newly detected polysialogangliosides. Thereafter, up to handling, parallel to increased growth and arborization of dendrites and axons as well as synaptogenesis, the newly detected polysialogangliosides decreased in favor of GD1b, GT1b, GQ1b, and GD1a. At hatching the myelin-specific GM4 appeared, reaching about 8% of total ganglioside sialic acid after 10 weeks. Likewise a fraction, migrating somewhat faster than GM1, increased. This band, named GM1', is suggested to be also myelin-associated. The other monosialogangliosides were always minor fractions, none exceeding 4% of total ganglioside sialic acid.

Gangliosides associated with microsomal subfractions of brain: comparison with synaptic plasma membranes

To study ganglioside distribution within subcellular components and test the hypothesis that they are localized at the nerve ending, microsomes and synaptic plasma membranes were isolated from young adult rat brains and compared with respect to ganglioside composition. These were shown to be heterogeneous preparations by fractionation on a discontinuous sucrose gradient into subfractions which had differing ganglioside concentrations. The highest ganglioside concentrations occurred in membranes banding at the 0.8M/1.0M and 1.0M/1.3M interfaces for both microsomes and synaptic plasma membranes. These subfractions had closely similar ganglioside concentrations and pattern distributions. In addition, the kinetics of ganglioside labeling following administration of [3H]-glucosamine were similar for the two preparations. The fact that microsomal subfractions representing heterogeneous mixtures of brain cell membranes showed close similarity to synaptosomal plasma membranes argues against localization of gangliosides at the nerve ending. These results, together with other lines of evidence, support the concept that gangliosides are distributed over large portions of the neuron (and perhaps other brain cells). Data concerning the labeling of gangliosides in different microsomal subfractions indicated a movement of label over time from the more dense to the less dense membranes, as was also noted for the glycoproteins in the same subfractions. Specific radioactivity of the gangliosides increased relative to that of the glycoproteins with time.