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Past studies have examined the inhibition of binding of mannose‐rich yeast to immobilized concanavalin A (Con A) in the presence and absence of specific saccharides. This is a model system for testing potential drugs that could block pathogen binding to human cells. Here 2.0M, 0.2 M and 0.02 M NaCl and KCl were tested in a much more extensive study than in the past, for their ability to inhibit binding of yeast (Saccharomyces cerevisiae) to immobilized Con A over a 30 min time course. In about 15,000 replicate experiments, both salts inhibited binding in a nearly identical way, in a concentration dependent manner, ranging from about 20% to about 60% reduced binding over controls. The salt effects reached a plateau at 20‐30 minutes, with 2.0 M salt showing the greatest inhibitory effects. These results are similar to those obtained in studies with specific saccharides, suggesting that salt effectively can block lectin‐saccharide binding, with possible implications in pathogen binding to human cells (Supported by NIH NIGMS SCORE (S0648680), MARC, RISE, the Joseph Drown Foundation and Sidney Stern Memorial Trust.

Here we quantitatively examine the kinetics of salt‐induced dissociation of mannose‐rich yeast (Saccharomyces cerevisiae) from concanavalin A (Con A) derivatized agarose beads. This model can be used to test a reagent's ability to elute glycan‐containing molecules from lectin beads in purification protocols and to remove pathogens from human cell surfaces in drug development studies. We chose one salt concentration (4.0 M potassium chloride) in this study in order to do many replicate experiments to statistically evaluate the reliability of this model system. Future work will test many reagent concentrations in dose‐response experiments to determine reagents that are most effective at the lowest concentrations. In 65 repeated trials, the kinetics of dissociation of yeast previously bound to Con A derivatized agarose beads in the presence and absence of the salt over a 60 min time course was measured. This was done by simply counting the yeast remaining on the beads at each time point. A repeated measures‐ANOVA indicated a significant effect of the salt on the number of bound yeast (F=70, p less than 0.0001) as well as a significant interaction between the treatment and time elapsed (F=25, p less than 0.0001). Two‐sample t‐tests comparing salt treated samples with controls indicated substantially increased dissociation in the salt treated samples (20 min p less than 0.0001, 40 min p less than 0.0001, 60 min p less than 0.0001). What is new here is the model. We know of no past work that measures dissociation kinetics in so simple, inexpensive and easily visualized a manner (Supported by NIH NIGMS SCORE S0648680, MARC, RISE, the Joseph Drown Foundation and the Sidney Stern Memorial Trust).

A model system was developed to quantitatively identify reagents that unclump cells (yeast, Saccharomyces cerevisiae). Biofilms, infections and cancer cells in the circulation often involve a clumped or adhering state. Reagents that unclump cells might help lead to the development of anti‐biofilm, anti‐infection and anti‐cancer cell survival drugs. Various sugars and an amino acid (0 mg/ml – 20 mg/ml) were tested for their ability to unclump low pH (2.4), flocculated, formaldehyde (1%) fixed yeast in distilled water. The yeast with and without the reagents were stirred in 0.5 ml droplets on glass microscope slides in distilled water and percentages of single yeast cells (vs clumped yeast) were recorded over a 60 min time course by focusing on the edge of the droplets in 923 total trials. Alpha methyl glucose, alpha methyl mannose and D‐glucose increased the percentage of single cells over controls in the absence of reagents (p less than 0.05), while L‐arginine did not and D‐fucose, alpha lactose and sucrose had inconsistent effects. Most important in this study was the development of an essentially no‐cost, remarkably simple assay, to quantitatively assess reagents that could clump or unclump cells (supported by NSF Presidential Award 0731633, NIH NIGMS SCORE S0648680, RISE, MARC, Joseph Drown Foundation, Sidney Stern Memorial Trust).