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L B Grabel

Publications and source records attributed to L B Grabel.

24 records · Page 2Linked to original sources
PubMed1983

Teratocarcinoma stem cell adhesion: the role of divalent cations and a cell surface lectin.

We describe two additive systems of intercellular adhesion in teratocarcinoma stem cells (Nulli cell line). One component is divalent cation-dependent (Ca++ or Mg++) and the other involves a cell surface fucan/mannan-specific lectin, previously identified on stem cells by an erythrocyte rosetting assay. The existence of these two systems is inferred from the observation that reaggregation of stem cells was partially inhibited by the removal of divalent cations or by the presence of lectin inhibitors such as fucoidan, but reaggregation was completely blocked when the two conditions were combined. Our results are related to recent work describing a calcium-dependent system of intercellular adhesion in teratocarcinoma stem cells.

Animals↗
PubMed1982

Carbohydrate specificity of sea urchin sperm bindin: a cell surface lectin mediating sperm-egg adhesion.

We have examined the carbohydrate specificity of bindin, a sperm protein responsible for the adhesion of sea urchin sperm to eggs, by investigating the interaction of a number of polysaccharides and glycoconjugates with isolated bindin. Several of these polysaccharides inhibit the agglutination of eggs by bindin particles. An egg surface polysaccharide was found to be the most potent inhibitor of bindin-mediated egg agglutination. Fucoidin, a sulfated fucose heteropolysaccharide, was the next most potent inhibitor, followed by the egg jelly fucan, a sulfated fucose homopolysaccharide, and xylan, a beta(1 leads to 4) linked xylose polysaccharide. A wide variety of other polysaccharides and glycoconjugates were found to have no effect on egg agglutination. We also report that isolated bindin has a soluble lectinlike activity which is assayed by agglutination of erythrocytes. The bindin lectin activity is inhibited by the same polysaccharides that inhibit egg agglutination by particulate bindin. This suggests that the egg adhesion activity of bindin is directly related to its lectin activity. We have established that fucoidin binds specifically to bindin particles with a high apparent affinity (Kd = 5.5 X 10(-8) M). The other polysaccharides that inhibit egg agglutination also inhibit the binding of 125I-fucoidin to bindin particles, suggesting that they compete for the same site on bindin. The observation that polysaccharides of different composition and linkage type interact with bindin suggests that the critical structural features required for binding may reside at a higher level of organization. Together, these findings strengthen the hypothesis that sperm-egg adhesion in sea urchins is mediated by a lectin-polysaccharide type of interaction.

Agglutination↗
PubMed1981

Specific rosette formation between fibroblasts and erythrocytes.

Fibroblast cells (BHK-21, Swiss 3T3, SV403T3, L929) will form rosettes by binding to erythrocytes of specific types. The specificity of binding varies with the cell line. Monolayer cultures of spread baby hamster kidney (BHK) cells also bind erythrocytes with the same specificity exhibited by suspended cells. Our studies have concentrated on rosette formation between trypsinzed-ox (TOx) erythrocytes and BHK cells. Extensive protease treatment of the BHK cells reduces their ability to bind TOx erythrocytes in a dose- and time-dependent manner, suggesting the involvement of protein in the binding site. Simple saccharides, and glycopeptide isolated from ox erythrocyte ghosts, do not inhibit rosetting. However, neutral glycosphinogolipids from ox erythrocyte ghosts inhibit BHK-TOx rosetting, whereas neutral glycosphingolipids from non-rosetting rabbit erythrocytes have no effect on rosetting. Furthermore, incorporation of ox glycolipids into guinea-pig erythrocytes causes these non-rosetting erythrocytes to adhere to BHK cells. These experiments suggest that specific glycolipids of the ox erythrocyte act as receptors for binding sites on the cell surface of BHK cells. These cell-specific binding sites may play a role in cell-surface events involving carbohydrate recognition.

Animals↗
PubMed1979

Teratocarcinoma stem cells have a cell surface carbohydrate-binding component implicated in cell-cell adhesion.

Teratocarcinoma stem cells maintained in the undifferentiated state express a carbohydrate-binding component that recognizes oligomannosyl residues. This cell surface molecule is detected by a rosetta assay in which the stem cells form rosettes with glutaraldehyde-fixed trypsinized rabbit erythrocytes. Addition of simple sugars to the assay mixture has little effect, but rosette formation is inhibited by a series of mannose-rich glycoproteins (yeast invertase, yeast mannans and horseradish peroxidase). Periodate oxidation eliminates the inhibitory activity of invertase whereas pronase digestion has little effect, indicating that carbohydrate moieties are essential for inhibition. Invertase and its glycopeptide derivatives also inhibit the reaggregation of dispersed stem cells and promote the dissociation of preformed aggregates. These results suggest that intercellular adhesion of teratocarcinoma stem cels may be the consequence of the interaction of a lectin-like component detected in the rosette assay with a complementary oligosaccharide receptor on adjacent cells.

Animals↗